NCUR CBS Abstracts

Salman Ali
Poster: “Using Genome Editing to Generate Point Mutants of Human Bcl-2 Protein Noxa to Study Its Function”
Salman Ali, Karl Krecke, Dr. Ameeta Kelekar, Department of Laboratory Medicine and Pathology, University of Minnesota Medical School

Human Noxa, the smallest known member of the BH3-only subgroup of Bcl-2 family proteins, is able to induce apoptosis by interacting with anti-apoptotic Bcl-2 proteins, such as Mcl-1. Noxa is transcriptionally induced in response to DNA damage in tumor cells of epithelial origin and promotes apoptosis by binding to its pro-survival protein Mcl-1 through its BH3 domain. However, in hematological malignancies, Noxa is constitutively expressed, suggesting that a post-translational mechanism may keep Noxa's pro-apoptotic function in check. Previous studies showed that a serine residue (S13) on Noxa, is phosphorylated by the kinase, CDK5. Phosphorylation occurred in a glucose-dependent manner and imparted pro-growth characteristics to leukemia cells, including increased glucose consumption for biomass production. These observations suggested a novel metabolic function for human Noxa. Our study aims to understand the functional consequences of S13 modification for Noxa-Mcl-1 interactions and for its pro-survival and metabolic functions. We hypothesize that biallelic loss of WT Noxa and introduction of S13A, a non-phosphorylatable serine mutant or S13E, a serine phospho-mimic, and inactivation of the BH3 binding domain via a D34A mutation, will have a profound impact on the ability of Noxa to regulate both metabolism and apoptosis. To generate the point mutants in the Noxa gene, we utilized a small guide (sg) RNAs carrying the mutation, single-stranded DNA oligos and Cas-9 messenger RNA with a CRISPR/Cas9 gene-editing protocol. Various techniques have been employed during our study, including cell culturing, transfection assays, cell lysate preparations, protein estimation assays, gel electrophoresis, and western blotting. Upon completion of this study, T cell lines expressing mutated Noxa will serve as tools for investigating the contribution of phosphorylation and protein interactions to the metabolic and cell survival roles of Noxa. It is anticipated that these studies will contribute to the design of novel therapeutic strategies against T leukemia.

Shayna Allen
Performing Arts: “Through the Lens of the People: An Inquiry into the Offshoots of a Grassroots Peace Summit in Ukraine”
Shayna Allen, Dr. Malinda Lindquist, Department of History, University of Minnesota

In the Summer of 2018, I received the Donovan Scholarship to pursue historical research in Ukraine. I decided to conduct this research using documentary film. Over 15 days, I conducted 29 interviews in Kiev, Kharkiv, and Lviv, Ukraine. Initially, the purpose for my research was to monitor any change or development in Ukraine since the Euromaidan Revolution of 2014. I had a focus group of the attendees of a (PEACE) Public Engagement and Civic Empowerment Summit. The goals of the PEACE Summit were to demonstrate the power of civic engagement, promote governmental decentralization, and develop systems that sponsor change from local sources. I would return to ask their impressions of the event, and ultimately, if they believe the goals of the event had been met. Once in Ukraine, I expanded beyond the PEACE Summit, and I interviewed a variety of people such as activists who participated in the Euromaidan protests, displaced Crimeans, students, and directors of non-government organizations. Beyond the efforts of the PEACE Summit, this project became entrenched in topics of displacement, Ukrainian autonomy, and hopes for the future of Ukraine. I was interested in creating a collaborative project and working with Ukrainians in the process. I traveled with an interpreter, and asked questions that would elicit personal stories. The complex issue of Ukrainian Identity is a core theme of my film. Film communicates the ambiguity and complexities of life, rather than simply an objective or statistical analysis.

Jacob Bernier
Poster: “Teaching the Next Generations: Canoe Resurgence for Indigenous Youth and Their Communities”
Jacob Bernier, Dr. Carter Meland, American Indian Studies, University of Minnesota

Indigenous peoples around the world are focusing on reclaiming aspects of their cultures, one of which being traditional watercraft. From the West Coast of the United States and Canada, to the vast Pacific, a resurgence of crafting canoes has been occurring and for good reason: to ensure that future generations can have the connection with their culture and the water. The discourse around canoe revitalization is narrow, but what has been published lists numerous positive outcomes for Indigenous communities, ranging from drug and alcohol prevention, to an increase in youths’ community engagement. Seeking to better understand the effects on youth, and using the framework of cultural healing, canoe resurgence is placed in the context of Indigenous cultural vitalization. Situated on the waters of Mni Sota Makoce (Minnesota), Dakota homeland , this study uses participant observation methods, focusing primarily on the impacts canoes have on the self-esteem of Dakota and Ojibwe youth, but also addresses some of the multigenerational impacts on their communities as a whole. This paper is broken down into several parts. First, a brief literature review serves as an introduction to the issues of canoe resurgence, followed by my personal experiences connecting with Dakota and Ojibwe communities throughout Minnesota. Then, I discuss the process of creating the instrument most used to propel a canoe through and on water; a paddle. In closing, the circle of knowledge continues with a look towards the future of Indigenous canoe resurgence.

Hannah Carlin
Poster: “A Novel Herpes Simplex Virus-Type 1 Glycoprotein C Mutant and Its Effects on Binding Host Heparan Sulfate and Release of Progeny Virions”
Hannah Carlin and Dr. Stephen Rice, Dept. of Microbiology and Immunology, University of Minnesota

Herpes Simplex Virus-Type 1 (HSV-1) infects over 80% of adult individuals in the world causing lifelong recurrent infections manifesting as cold sores, eye infections and/or encephalitis. Although several aspects of the replication life cycle of HSV-1 are well understood, little is known about how progeny viruses are released from the host cell at the end of the viral replication cycle. Recent studies have indicated that, in infected Vero cells, ~10% of progeny virions are released into the cell supernatant at the end of infection, whereas the remaining 90% persist on the extracellular membrane of the infected host cell. It is unknown how these progeny viruses attach to the membrane or how their detachment is mediated. We hypothesized that the surface attachment of progeny virions is mediated by the viral glycoprotein C (gC), via its ability to bind to host cell heparan sulfate (HS) moieties. Moreover, analysis of an HSV-1 gC deletion mutant confirmed that gC is a key determinant of viral release. To further our analysis, we now report that we have used CRISPR-Cas9 mutagenesis to engineer and isolate a novel HSV-1 gC mutant, 5RA. The 5RA mutant encodes a gC molecule unable to bind to HS due to point mutations that alter key arginine residues needed for HS interaction. We are currently characterizing the replication and release phenotypes of 5RA, comparing it to both WT HSV-1 and the gC deletion mutant. These results will indicate whether the HS-binding activity of gC modulates the release of progeny virions from the infected cell surface.

Rachael Dumas
Poster: “Neural Correlates of Self-Referential Processing in Longitudinal Risk for Adolescent Suicide”
Rachael Dumas and Dr. Karina Quevedo, Department of Psychiatry, University of Minnesota

BACKGROUND: Suicide is the second leading cause of death in those between the ages of 12 and 25. Research into adolescent depression has revealed that neural correlates of self-referential processing are linked to suicide attempts. Though much research has been done into predictors of suicide ideation and attempts, there is a lack of knowledge regarding factors that influence longitudinal risk for adolescent suicide, which the present study aims to address. METHODS: During a self-other face recognition task, adolescents saw photographs of faces displaying happy, sad, or neutral expressions and identified whether the face was familiar (self) or unfamiliar (other). Participants completed the Suicide Ideation Questionnaire (SIQ) at scan time and a year and a half later. Suicide ideation change was calculated by subtracting initial scores from follow-up scores. A median-split was used to determine whether a participant’s suicide ideation had gotten better or worse. Participants whose suicide ideation worsened were compared to those whose improved through patterns of brain activity during self versus other face recognition. RESULTS: Main effect group: Adolescents whose suicide ideation worsened had more activation in the occipital gyrus and cuneus (BA 19). Group by self-face interaction: Adolescents whose suicide ideation worsened had more brain activation in the cerebellum (BA 37), fusiform gyrus, and middle frontal gyrus (BA 8, 46) during self-face versus other-face recognition. In contrast, adolescents whose suicide ideation diminished had more activity in those areas during other-face recognition versus self-face recognition. Group by self-face by emotion interaction: Adolescents whose suicide ideation worsened had higher activity in the insula, putamen (BA 13), inferior frontal gyrus (BA 47), precuneus, and superior parietal lobe (BA 5, 7) while recognizing happy self-faces, but adolescents whose suicide ideation diminished showed the opposite pattern. These results have implications for identifying self-referential neural processes linked to longitudinal risk for adolescent suicide.

Cameron Durfee
Poster: “Human APOBEC3B and HPV E6 And E7 Oncoproteins in Tumorigenesis in Vivo”
Cameron Durfee, Lindsay Larson, Emily Law, Reuben Harris, and Prokopios Argyris, College of Biological Sciences, University of Minnesota

In vitro and in silico data indicate that APOBEC DNA cytosine to uracil deaminases induce a large percentage of mutations in multiple human tumor types. These mutations contribute to observed tumor heterogeneity including metastasis. In cervical cancer, APOBEC3B overexpression is caused by the E6 and E7 oncoproteins of high-risk human papillomaviruses (HPV). We hypothesize that in addition to inducing APOBEC3B overexpression, the HPV E6 and E7 oncoproteins sensitize the human genome to APOBEC3B catalyzed mutagenesis in part by p53 inactivation and in part by additional mechanisms. To test this hypothesis, we have combined a new model for human APOBEC3B expression in mice with an established model E6 and E7 driven tumorigenesis. Standard breeding was used to generate 3 cohorts of 80 animals each, with each cohort consisting of 10 wild-type, 10 E6, 10 E7, 10 E6/E7 animals both with and without APOBEC3B. The first cohort was observational, the second was treated rectally with DMSO, and the third was treated rectally with the chemical carcinogen DMBA. These studies are ongoing but the results to-date will be presented including progression-free survival data and immunohistochemistry studies.

Anna Hance
Poster: “Development of a Stromal-Free Culture Protocol to Induce Robust Expansion of B Cells for Therapeutic Applications”
Anna Hance, Sabarinathan Ramachandran Ph.D, and Bernhard Hering, MD. Department of Surgery, University of Minnesota

B cells, because of their ability to present self-antigens, have been shown to play a crucial role in autoimmune disorders and in cancer immunosurveillance. Depending on their activation state and the presence of co-stimulatory signals, B cells can be antigenic or tolerogenic. Studies in the literature have demonstrated the therapeutic utility of B cells as APCs for potent malignant cell-specific treatment for cancer that avoids the harmful off-target effects of traditional treatments and in the field of transplantation to induce donor-specific tolerance. The overall aim is to develop an approach to a stromal-free cell culture protocol to induce robust expansion of B cells that can be translated into a clinical setting. In the first series of studies, we isolated naïve, memory and total B cells from peripheral blood using antibodies specific for CD20+ and CD27+. Enrichment of the B cell populations were performed using CD20+ magnetic beads for positive selection (Miltenyi Inc) and negative selection using Naive B cell enrichment kit (Stemcell Technologies). In order to optimize the growth factor and cytokine concentrations needed for optimal expansion of the B cells, we utilized a Design of Experiment study with varying concentrations of IL-4, IL-21, IL-2, IL-10, CD40L-multimer, BAFF, and seeding densities. The ex vivo expanded B cells ability to induce/suppress effector T cell responses and induce regulatory immune cell subsets were analyzed by co-culture studies. Expansion of the purified B cells with IL-4 (10ng/mL), IL-2 (5ng/mL), IL-10 (40ng/mL), IL-21 (10ng/mL), CD40L-multimer (500 or 1000ng/mL) and BAFF (10ng/mL) for 14 days ex vivo. Flow cytometric analysis demonstrated that the expanded B cells were >95% pure and 99% viable. The naïve B cells expanded 4.1-fold, memory B cells expanded 42.6-fold and total B cells expanded an average of 45-fold, indicating that memory and total B cells showed a significant potential for expansion.

Rabab ibrahim
Poster: “TORSINA and LAP1 Promote Rearward Nuclear Movement and Centrosome Orientation in Migrating Fibroblasts by Inhibiting LULL1, a Negative Regulator of CDC42 Activation.”
Rabab Ibrahim, Gant Luxton, Department of Genetics, Cell Biology and Development, College of Biological Sciences, University of Minnesota

Cell migration plays a key role in the development and maintenance of multicellular organisms. It was recently found that migrating cells move their nuclei rearward in an actin-dependent manner resulting in centrosome orientation towards the leading edge, which is critical for efficient directional cell migration. Rearward nuclear movement requires the luminal ATPase torsinA and its activator, the inner nuclear membrane lamina-associate polypeptide 1 (LAP1). In contrast, we found that another torsinA activator, an endoplasmic reticulum/outer nuclear membrane protein, luminal domain-like LAP1 (LULL1) was dispensable for this process. To understand the mechanism underlying torsinA/LAP1-dependent nuclear movement, we performed RNA interference-mediated epistasis experiments in NIH3T3 fibroblasts and found that simultaneous depletion of torsinA and LAP1 inhibited rearward nuclear movement and centrosome orientation to levels similar to individual protein depletion, suggesting that torsinA and LAP1 function in the same pathway to promote this process. The co-depletion of LULL1 and torsinA, or LAP1, resulted in normal levels of rearward nuclear movement and centrosome orientation. Moreover, we found that unlike serum-starved control cells, LULL1-depleted cells oriented their centrosomes independent of lysophosphatidic acid, a serum factor known to stimulate these processes in serum-starved cells. Centrosome orientation can also be triggered in serum-starved cells expressing either constitutively active cdc42 or its downstream effector the serine/threonine kinase MRCK. Since the expression of either of these constructs can rescue rearward nuclear movement in torsinA- or LAP1-depleted cells, we hypothesize that torsinA and LAP1 promote nuclear movement in migrating fibroblasts by inhibiting LULL1, a negative regulator of cdc42. Our findings provide further evidence to support the emerging model of the nuclear envelope as a key signaling node in migrating cells. Given that mutations in torsinA and LAP1, cause the neurological movement disorder DYT1 dystonia, our results also highlight the possible connection between defective directional cell migration and this debilitating disease.

Taylor Intihar
Poster: “Tumor Suppressor P53 Promotes Degradation of the Stress Transcription Factor HSF1 and Worsens Huntington’s Disease Pathology.”
Taylor Intihar, Nicole Zarate and Dr. Rocio Gomez-Pastor, Department of Neuroscience, University of Minnesota School of Medicine

Huntington’s disease (HD) is a neurodegenerative disorder characterized by motor and cognitive decline due to the progressive loss of medium spiny neurons (MSNs) in the striatum. HD is caused by an expanded CAG repeat in the Htt gene, leading to protein misfolding and aggregation. We showed that Heat shock transcription factor 1 (HSF1), critical for the regulation of protein folding and synapse formation, is degraded in HD, contributing to MSNs death and HD pathology. Understanding the mechanism behind HSF1 degradation is critical to design effective therapies to increase HSF1 levels in MSNs and ameliorate disease. HSF1 is degraded by sequential phosphorylation and ubiquitylation reactions mediated by the protein kinase (CK2α’) and the E3 ligase Fbxw7. Both CK2α’ and Fbxw7 are transcriptionally up-regulated in MSNs of HD mouse models and human iPSCs differentiated into MSN-like cells by an uncharacterized mechanism. Via in silico analyses of CK2α’and Fbxw7 gene sequences, we observed the presence of putative regulatory binding sites for the tumor suppressor p53, a gene previously implicated in the HD pathology. Our preliminary data showed that p53 is up-regulated in MSNs in HD mice, where CK2α’ and Fbxw7 are induced. Using chromatin immunoprecipitation, we demonstrated that p53 binds to CK2α’ and Fbxw7 gene sequences and that such binding is enhanced in HD striatal-like cells. p53 pharmacological inhibition (Pifithrin-α) and siRNA treatments resulted in down-regulation of CK2α’ and Fbxw7 and increased HSF1 protein levels. Our work demonstrates the role of p53 as an upstream component of the HSF1 degradation pathway in HD.

Leslie Kent
Poster: “Mucin Impacts Pseudomonas Aeruginosa Biofilm Growth on Endotracheal Tubing”
Leslie Kent, Ryan Hunter, Microbiology & Immunology, University of Minnesota

Ventilator-associated pneumonia (VAP) is a type of pneumonia that occurs following mechanical ventilation in 250,000-300,000 United States patients annually (Koenig, 2006). Mechanical ventilation requires the insertion of an endotracheal tube (ETT) through the nose, mouth, or hole in the throat into the lungs. VAP diagnosis is correlated with several pathogenic bacteria with one of the most common being Pseudomonas aeruginosa (Chastre, 2002; Gil-Perotin, 2012). Many of these bacteria, including P. aeruginosa, are biofilm forming, and ETT provides a surface for this growth. Biofilms increase bacteria’s ability to grow, including contributing to antibiotic resistance by protecting bacteria living inside the biofilm. As such, being able to minimize biofilm growth of pathogens like P. aeruginosa is an important aspect of VAP-related research. In the context of Cystic Fibrosis, it has been found that in vitro biofilm formation of P. aeruginosa is increased by the addition of mucins by Landry et. al, who proposed that P. aeruginosa have a mucin-specific adhesion which immobilizes them on the lung surface. If this property holds true on ETT, mucin may be contributing to biofilm formation and, ultimately, VAP. It is hypothesized that the addition of mucin during P. aeruginosa biofilm formation on ETT increases growth. Using GFP-tagged P. aeruginosa in varying concentrations of mucin, I am currently working to: (1) image biofilm growth using fluorescent microscopy, (2) quantify biofilm growth using ImageJ, and (3) image biofilm growth using Scanning Electron Microscopy. We expect to see that biofilms grown with higher concentrations of mucin will have more P. aeruginosa and be more structurally robust. This may be because P. aeruginosa uses mucin in building an extracellular matrix during biofilm formation. Further research questions include measuring the added impact of antibiotics and various anaerobic bacteria commonly found in human lungs on P. aeruginosa biofilms.

Isabel Larus
Poster: “Effect of Quorum Quenching Lactonases in Clinical Isolates of P. Aeruginosa”
Isabel Larus and Dr. Mikael Elias University of Minnesota Department of Biochemistry, Molecular Biology, and Biophysics

Pseudomonas aeruginosa infection is common in cystic fibrosis patients and has been found to be a major predictor of morbidity and mortality in these individuals. Quorum sensing (QS) is a cell-cell communication process utilized by gram-negative bacteria such as P. aeruginosa that involves production, detection, and response to signaling molecules called autoinducers, typically acyl-homoserine lactones (AHLs), as a function of cell density. In response to a minimum threshold concentration of AHLs, gram-negative bacteria alter gene expression regulating multiple processes including virulence, pathogenicity, and biofilm production. A type of enzyme called lactonases have the ability to hydrolyze AHLs, quenching QS between gram-negative bacteria. Two such lactonases, GcL and SsoPox have been shown to be effective in quorum quenching. A violacein-negative mutant of Chromobacterium violaceum (CV026) can be induced to produce violacein if incubated with AHLs with N-acyl side chains from C4 to C8. P. aeruginosa produces AHLs with C4 N-acyl side chains and can induce violacein production in CV026 in various concentrations depending on AHL concentration. Here, we expect to show that, when incubated together, AHLs in supernatant from clinical isolates of P. aeruginosa from cystic fibrosis patients can be detected by and induce pigment production in CV026 as compared to E. coli, which does not synthesize AHLs. We also expect to show that incubation of CV026 with both AHLs from these clinical isolates and lactonases SsoPox or GcL will result in reduced pigment production levels, demonstrating that SsoPox and GcL can successfully quench quorum communication in the P. aeruginosa clinical isolates under these conditions. An understanding of the capacity of GcL and SsoPox to quench QS in P. aeruginosa clinical isolates will provide valuable information about potential therapies for treating P. aeruginosa infections in cystic fibrosis patients.

Konstantin Mamedov
Oral: “Synthesis and Characterization of Hollow Gold Nanoparticles for Gene Delivery”
Anisha Veeren, Joseph Zasadzinski, Department of CEMS;  Sarah Merkel, Mark J. Osborn, Department of Pediatrics, University of Minnesota

Abstract: Intracellular drug and gene delivery requires overcoming the barrier to endosome escape. Genetic materials and protein function in the cell cytosol, but typically < 2% of mRNA delivered via synthetic vectors reach their destination. Our strategy is to use liposomes coated with gold nanoparticles that can be triggered by picosecond pulses of near-infrared light to release biomolecules from the endosomes. The NIR light pulses generate vapor nanobubbles that mechanically rupture the liposome and endosome, releasing the mRNA to the cell cytosol. Here we describe two methods of attaching gold nanoparticles to liposomes to generate nanobubbles. The first method creates plasmon resonant hollow gold nanoshells (HGN) via a galvanic replacement reaction of gold salts with cubic silver template nanoparticles. These HGN are tethered to the liposomes via thiol terminated polyethylene glycol lipids on the liposome surface. In the second method, plasmon resonant gold nanoparticles are directly condensed onto the liposome exterior via reduction of chloroauric acid. We examine the threshold fluence and wavelength dependence necessary to rupture the liposomes and release mRNA into solution to determine an optimal mRNA delivery system.

Abigayle McClendon
Poster: “Reduced Hippocampal Volume in Comorbid Alcohol Use Disorders and Major Depression”
Abigayle McClendon, Sylia Wilson, William Iacono, University of Minnesota

Previous research indicates that people with both Major Depressive Disorder (MDD) and Alcohol Use Disorder (AUD) have been found to have smaller hippocampal volume compared to people without the disorders. A majority of studies that have looked at the effects of MDD on hippocampal volume have controlled for the presence of AUD and other substance use. Of the studies that have looked at the effects of AUD on hippocampal volume, a few have controlled for the presence of MDD. We examined whether the comorbidity of AUD and MDD plays a role in the hippocampal volume decrease that has been associated with both disorders in a sample of N = 411 adult twins classified into one of four groups: (1) MDD and no AUD (n = 97), (2) AUD and no MDD (n = 70), (3) MDD/AUD (n = 61), and (4) No MDD or AUD (n = 195). Freesurfer was used to gather data on hippocampal volume and a series of linear mixed models was used to compare the four groups. The four groups did not have any significant difference in volume when compared to each other. The Alcohol Use Index showed a significant negative association specifically in females. The nonsignificant results between groups might reflect a lack of current depressive symptomology in the sample, a possibility we will explore in future research.

Morgan McCullough
Poster: “Characterizing PELP1 L798CFS*14 in Colorectal Cancer”
Morgan McCullough, Dr. Julie Ostrander, Department of Medicine, Masonic Cancer Center at the University of Minnesota

Each year, there are over 750,000 cases of colorectal cancer (CRC), making it the third-most frequently diagnosed cancer. CRC is an especially difficult burden because about 25% of patients are diagnosed after tumors have become metastatic, and 90% of metastatic CRCs become resistant to standard treatments. It is hypothesized that cancer stem cells (CSCs) play a role in CRC recurrence and therapy resistance. CSCs are non-proliferative, and frequently exist as a minority sub-population of cells in recurrent therapy-resistant tumors and are hypothesized to account for high mortality among patients with advanced disease. The identification of the intracellular signaling pathways that drive the survival and expansion of CSCs is urgently needed to target this population of cancer cells. Previous research from the Ostrander laboratory has found that PELP1 signaling promotes CSC biology in breast cancer. PELP1 is primarily a nuclear protein in normal tissues but has been shown to be overexpressed and/or differentially localized to the cytoplasm in many types of cancer. Altered expression of PELP1 can transform cells, and can promote tumor cell proliferation, survival, and migration. Despite these observations, PELP1 remains understudied in the context of CRC. Interestingly, we observed a specific mutation in PELP1 (L798Cfs*14) in CRC that is frequently associated with a mutation in the oncogene, BRAF (V600E). CRC expressing the BRAF V600E mutation represent a rare subset of CRCs that are much more resistant to standard treatment than other CRCs. This study aims to characterize the PELP1 L798Cfs*14 mutation in BRAF V600E-positive CRC. We have developed cell line models to test our hypothesis and assays to assess the effect of PELP1L798Cfs*14 on CRC cell migration, proliferation, survival, and CSC biology are currently underway.

Dakota Milianta-Peterson
Poster: “SIV△Nef Vaccine-Induced Protection Associated with Increased Follicular to Extrafollicular Ratios of Virus-Specific CD8 T Cells in Lymphoid Follicles”
Dakota Milianta-Peterson, Gwantwa Mwakalundwa, Reece Wagstaff, Hadia Mohammad, Paul R. Johnson, and Pamela J. Skinner, Department of Veterinary and Biomedical Sciences, University of Minnesota

During HIV and simian immunodeficiency virus (SIV) infections, virus replication becomes concentrated within lymphoid B cell follicles. While CD8+ T-cells play a vital role in controlling viral replication, they generally do not accumulate to high levels in follicles. Through yet to be fully understood mechanisms, live-attenuated vaccines (LAV) with a nef gene knockout (SIV△nef) have been highly effective in preventing (SIV) infections. SIV△nef vaccination induces protective immunity in 94% of vaccinated animals, with 50% showing sterilizing immunity against challenge with pathogenic SIV in rhesus macaques. Previous research has shown that there is a maturation of protective immunity between 5 and the 20 weeks post-vaccination. We’ve previously shown that this maturation is not associated with changes in the abundance or location of virus-specific CD8+ T-cells. Our current hypothesis is that this maturation of protection is associated with an increase in virus-specific CD8+ T-cell accumulation in lymphoid follicles. To test this hypothesis, lymph node and spleen tissues samples from rhesus macaques collected at 5 weeks and 20 weeks post-vaccination with SIV△nef were stained with reagents that stain B cell follicles, imaged with a Zeiss confocal microscope, and virus-specific CD8+ T-cells were quantified in both the B-cell follicles and the extrafollicular zones. We found that vaccine-induced protection was associated with a slight increase in virus-specific CD8 T cells in follicles. In addition, we found, a significantly higher follicular to extrafollicular (F:EF) ratio of virus-specific CD8 T cells in the 20-week immune group compared to the 5-week non-immune group in both the spleen and lymph nodes. These findings indicate that the maturation of vaccine-induced immunity is associated with a higher F:EF ratios of SIV-specific CD8 T cells. These findings may help inform the development of a successful HIV vaccine.

Narra Moreen
Poster: “The Effects of the College Experience on Multiracial Identity Development”
Narra Moreen, Christine Wu, and Dr. Richard Lee, Department of Psychology, University of Minnesota

Psychosocial theories of student development suggest that college is a critical time for identity development among emerging adults. However, there are large research gaps related to identity development among multiracial college students. For multiracial individuals, the process of identifying with one or more racial groups involves choices about what racial messages from family and peers to accept and internalize. The goal of the current study is to investigate the role of the college experience on the identity development of multiracial individuals. Multiracial undergraduate students were recruited to participate in semi-structured interviews about factors affecting their identity development before and during college. Participants (N = 20; 11 females) are between 18-23 years old (M = 20.37 , SD =1.38) and are either currently attending or recently graduated from a large Midwestern public institution. Data collection is ongoing with 18 completed interviews so far. Qualitative data will be analyzed using thematic analysis. We expect to find that the shift in context when moving from home to college had an effect on the way participants view their identities, especially for those coming from areas with low racial diversity. Additionally, we expect multiracial students' awareness of inclusive and accepting social groups to be a major factor in how supported and structurally acknowledged they feel. We also expect group representation to be an important factor in identifying and exploring an identity in more than one group. Future research directions and implications for student affairs practitioners will be discussed. For example, student affairs practitioners at post-secondary educational institutions should acknowledge and include the multiracial population and their narratives in existing support structures for marginalized groups.

Sowmya Narayan
Poster: “Pavlovian to Instrumental Transfer Phenotypes in Mice with Autism-Associated NLGN3 Mutation”
Sowmya Narayan, Dr. Patrick Rothwell, Department of Neuroscience, University of Minnesota

The presence of conditioned stimuli associated with drugs of abuse is known to exacerbate drug-seeking behaviors and addiction. This phenomenon can be modeled in the laboratory using the Pavlovian-Instrumental Transfer (PIT) paradigm in mice, in which presence or absence of conditioned stimuli changes an individual’s reaction toward a reward. In this experiment, mice are trained in three sequential stages: in the first, mice associate a tone with a food reward (Pavlovian); in the second, mice press a lever to receive the food reward (Instrumental); in the third, mice are re-exposed to the tone and allowed again to press the lever for food reward (Transfer). The nucleus accumbens, an area of the brain responsible for reward-seeking behavior, motivation and learning, contains dopaminergic signaling pathways which mediate PIT. Our laboratory has recently discovered synaptic dysfunctions within the nucleus accumbens of mice expressing an autism-associated knock-in (KI) mutation of the neuroligin-3 (NLGN3) gene. These mice exhibited more repetitive behaviors and subsequent enhanced learning in motor routine tasks, traits commonly seen in autism. In light of these behavioral phenotypes and the known deficits in the nucleus accumbens caused by the mutation, we hypothesized that NLGN3 mice would not undergo transfer as readily. Towards this prediction, our preliminary data show that NLGN3 KI mice are less likely to undergo PIT, suggesting differences in reward seeking. Further investigation into the mechanisms of these neural pathways could lead to a better understanding of the role of learning in both addiction and autism.

Sumaya Noor
Poster: “Perceptions of Physical Activity in the Somali Community of the Twin Cities of Minnesota”
Sumaya Noor, Fahima Osman, and Sarah Sevcik MPH, MEd, School of Public Health, University of Minnesota

This qualitative research investigates the perceptions of physical activity held by Muslim Somali men and women in the Twin Cities of Minnesota. Following the civil war in Somalia in the early 90s, Minnesota received a large influx of Somali-identified people who eventually formed the largest Somali community in the country. As members of this community, we have observed the wide array of beliefs in how Somali people view physical activity and its importance. Little information exists in the literature about the physical activity levels of Somali-identified people since most of this health information is categorized by race. Semi-structured interviews were conducted in Spring 2018 with participants recruited from local college campus’, mosques, and community centers. Questions probed at how factors such as age, gender, and immigration status impact physical activity. A total of eighteen adult participants were interviewed, eight males and ten females. Data analysis of transcripts included data reduction, conclusion drawing, and verification, using at least two independent reviewers at each stage to protect against bias. Preliminary results demonstrate that most participants conveyed that their religion and culture promote health, but may hinder rates of physical activity. Results also show that changes in lifestyle between Somalia and the US have a direct effect on the decreased rates of physical activity. Immigrant participants listed a different set of needs upon coming to the United States, and physical activity did not rank highly on that list for most. Implications for practice will be discussed, including the need for culturally relevant health promotion as a means of adaptation into the westernized culture and the need for interventions that allow students to incorporate physical well-being with their studies.

Jeffrey O'Brien
Oral: “Online Map for Rhizomes of Mexican American Art Since 1848”
Jeffrey O'Brien and Dr. Karen Mary Davalos, Chicano and Latino Studies, University of Minnesota Twin Cities

Rhizomes of Mexican American Art since 1848 is a project directed by Karen Mary Davalos, a professor of the Chicano and Latino Studies department at the University of Minnesota. This project will aggregate digital collections of Mexican American art and related documentation held by libraries, archives, and museums (LAM) throughout the United States and will culminate in an online portal to display this material to the public. However, this process is very difficult as there is not a reliable source that facilitates nation-wide access to Mexican American art. Therefore, the research team analyzed the current landscape of collecting institutions, and I was assigned the task of creating an online map to visualize the data using ArcGIS. The online map allows for a geographical representation of known LAMs in the United States. It is dynamic, and it can be instantly updated as new LAMs and collections are discovered. The map details the address, longitudinal and latitudinal coordinates, the type of institution, and collections for any given LAM. Likewise, it shows a clear distinction between different types of institutions such as libraries and museums. This is important since different institutions can classify materials in unique non-standard ways. The ArcGIS platform also allows for the individual collections within the institutions to be shown on the map. These seamlessly interfaced descriptions allow Dr. Davalos and her research team to better understand what is collected and where. The map drives priorities and strategies for connecting with LAMs who can contribute materials to the online portal. The online map created for Rhizomes serves to augment the way humanities scholars research Mexican American art in an unprecedented manner. There is endless potential to expand the map as time progresses and its ability to be accessed by a basic link makes it useful for researchers of all ages.

Angela Richards
Oral: “Indigenous Healing Through Art”
Angela Richards, Carter Meland, American Indian Studies, University of Minnesota

In like manner to the Indigenous peoples of North America and their ancestral lands, Indigenous artistic expression also experienced the assault of colonization. Indigenous intellectual and visual sovereignty was disrupted during the Indian boarding school era of the nineteenth century. As a result, historical trauma, or intergenerational trauma is manifested in the descendants of the Indigenous population of North America today. With the belief that art is medicine, and that there is profound healing in art, Indigenous artists such as myself are actively engaging in healing from the lasting impact of colonization. This research ​is situated in critical Indigenous studies by examining peer-reviewed articles from prominent Indigenous curators, artists, and educators. Using this framework, I reflect on the mirroring technique utilized in my own personal healing journey with art in connection with other contemporary Indigenous art and the assertion of the Indigenous narrative through the expression of internal emotions and expression of external reality. It is through art that the Indigenous artist takes control of their story/narrative and harnesses the transformative power of truth-telling and healing. This study maintains that contemporary Indigenous art is the interweaving of the ancestral past coupled with the artistic expression of the ongoing Indigenous experience. In order to comprehend the complexities of Indigenous art one must understand the importance of the relationship to the land and the kinship upon that land. Healing within Indigenous communities starts with institutional and fundamental change. Uprooting from colonization through engagement in truth-telling regarding colonization is the beginning of healing within Indigenous communities. I find that the implementation of Indigenous art therapy, the establishment of Indigenous art history discourse, and the continuation of contemporary Indigenous art space is vital to the survivance of Indigenous expression.

Thomas Richardson
Poster: “Further Research into High Strain Magnetostriction in a Ferromagnet-Polymer Composite"
Thomas Richardson, Austin Schleusner, and Professor Dan Dahlberg, School of Physics and Astronomy, University of Minnesota

Building upon our previous research, we have improved the high strain metal-polymer composite magnetostrictive material we developed. We have produced ferromagnetic-polymer composites that exhibit reversible strains up to nearly 25% in applied magnetic fields on the order of 3 kOe. The composites consisted of mixtures of Ecoflex 00-10 silicone rubber polymer, optimized to approximately 22 percent silicon thinner by mass, and homogeneously distributed randomly oriented high-carbon steel wire, cut to lengths of approximately 1.50 cm, 0.75 cm, and 0.50 cm. The wire loading ranged from 0.010 to 0.100 as measured by volume fraction. We applied a magnetic field of 3.0 kOe to the composites, which rotated wires inside material, thus causing a measurable strain. Wires of length 1.50 cm produced higher strains with increased loading up to a maximum strain of 12.0% at 0.025 loading; additional increases in loading decreased the strain, likely due to the structural problems associated with overlapping wires. This obstruction was reduced by using shorter wire lengths. Using wires of length 0.75 cm we were able to achieve 17.0% maximum strain, and using wires of length 0.50 cm we were able to achieve 24.9% maximum strain, both at the higher value of 0.070 loading. A plot of the strain vs wire loading can be found by following the link to extra materials.

Gracelyn Richmond
Oral: “Antibiotic Resistance Plasmid Retention in the Emergent Uropathogenic E. Coli Sequence Type ST1193 in the Absence of Selective Pressure”
Gracelyn R. Richmond, Dr. Bonnie Weber, Dr. Timothy J. Johnson, Department of Veterinary and Biomedical Sciences, University of Minnesota

Urinary tract infections (UTIs) account for almost 25% of all infections reported to clinicians and 60% of all women report at least one UTI in their lifetime. One in three women will require a course of antibiotics to treat a UTI before they are 24 years old. Due to many circumstances, antibiotic-resistant infections are on the rise. To exacerbate the issue, fewer new antibiotics are entering the market making extensively drug resistant and pan-resistant infections nearly impossible to treat. There has been a significant push to reduce antibiotic use to preserve their potency. However, the question still remains: will the rising tide of antibiotic resistance continue, or reverse as antibiotic use declines? Since many antibiotic resistance genes are spread among bacterial communities via plasmids, the ability to predict how a bacterial population’s overall resistance gene repertoire will change depends in part on plasmid retention dynamics. To study the retention of an antibiotic resistance plasmid in a uropathogenic E. coli strain in the absence of antibiotic selection, long-term evolution experiments were conducted. Uropathogenic E coli strain CVAST0752, belonging to the ST1193 clonal group and carrying resistance genes on plasmids, was subcultured daily for 78 days in the absence of antibiotics. Isolates were screened for its multi-drug resistance plasmid via PCR, and percent retention by the evolving population was calculated. It was expected that the plasmid would have a retention drop off to zero, however, this was not observed. This may be due to the presence of beneficial housekeeping genes on the plasmid making the plasmid less costly to retain. In addition, the plasmid or bacterium could undergo rapid mutation. This has implications for UTIs, as decreasing antibiotic use may not decrease resistant infections since the plasmid that incurs resistance is still present in the population when antibiotic use is eliminated.

Yasmeen Saad
Poster: “Pathovar Identification of Unknown Xanthomonas Translucens Isolates from Economically Important Small Grains”
Y. S. Saad (corresponding author), K. E. Ledman, R. D. Curland, C. A. Ishimaru, and R. Dill-Macky Department of Plant Pathology, University of Minnesota

Bacterial leaf streak (BLS), caused by the bacterial pathogen Xanthomonas translucens, is an important disease of small grains that cause yield losses which negatively impact farmers. Four main pathovars of X. translucens affect small grains: X. translucens pv. cerealis (Xtc), X. translucens pv. secalis (Xts), X. translucens pv. translucens (Xtt), and X. translucens pv. undulosa (Xtu). Identifying the diversity of a pathovar’s infrasubspecific taxa distinguished by their host range on small grains is key to developing effective control strategies for BLS. The objectives of this study were (1) to determine if the host reactions of small grains to X. translucens pathovar strains aligns with the phylogeny created by multi locus sequence analysis (MLSA) and (2) to use these combined data to identify unknown isolates, originating from intermediate wheatgrass and barley, to the pathovar level. Four pathotype strains and eight unknown isolates of X. translucens were infiltrated into seedling leaves of five small grains crops; wheat, barley, rye, oats, and intermediate wheatgrass. Qualitative data were recorded three days post inoculation (dpi) by observing the presence of water-soaking, chlorosis, and necrosis. Quantitative data were taken nine dpi by measuring lesion lengths. A phylogeny was constructed via Bayesian analysis of concatenations of four housekeeping genes (rpoD, dnaK, fyuA, and gyrB) for all strains, and analyzed by MLSA. In planta host reactions correlated with the clades generated by the MLSA of the X. translucens unknown isolates and reference strains. Using these data, all four strains isolated from intermediate wheatgrass were identified as Xtu. Of the four unknown strains isolated form barley, three were determined to be Xtt, while one was identified as Xtc. Our findings, which suggest that the X. translucens populations on intermediate wheatgrass and barely differ markedly, may help inform the development of control strategies to BLS in these crops.

Carmen Santana-Gonzalez
Poster: “Amygdala Connectivity During Emotion Regulation in Depressed Adolescents with Non-Suicidal Self Injurious Behavior (NSSIB).”
Carmen Santana, Jia Yuan Teoh, Madelyn Castro, Maggie Engstrom, and David Porter PhD, Department of Psychiatry, University of Minnesota

Non-suicidal self-injury (NSSI) is a public health concern with 50% of people who self-injure reporting attempting suicide at least once. The typical age of onset is 12-14 years and 14-15% of adolescents and young adults report a history of self harm. Past research suggests that NSSI is due to dysregulated emotions. We sought to understand the neural circuits of NSSI by testing amygdala connectivity during an emotion regulation task. Adolescents either passively viewed emotionally valanced images (passive viewing) or tried to regulate the emotions the pictures elicited (regulation). Images were displayed in 4 content blocks: NSSI images garnered from pictures teens post online, and negative, neutral or positive images from the international affective picture system. We found that connectivity between amygdala and the precuneus and superior temporal gyrus (STG) varied as a function of group and picture content. Depressed adolescents with NSSI had higher amygdala to precuneus and STG connectivity during NSSIB pictures and lower connectivity during standard negative pictures for regulation versus passive image viewing. Conversely, healthy controls showed higher amygdala to STG connectivity during standard negative pictures and lower connectivity during self-harm pictures, and similar amygdala to precuneus connectivity for self-harm and negative pictures as compared to neutral and positive pictures during regulation versus passive viewing condition. The precuneus underpins attentional resources deployed to down regulate negative affect. Higher amygdala to precuneus connectivity for NSSI pictures, suggest difficulty in using higher order cortical systems to reframe emotional evaluations in depressed youth with NSSI. Establishing which emotion regulation circuitries are dysfunctional in NSSI is important in helping guide the development of effective tailored treatments.

Garrett Schwartz
Poster: “Peer Victimization in Adolescence Is Negatively Associated with Brain Volume in a Subsample of Post-Institutionalized Youth”
Garrett N Schwartz, Max P Herzberg, Kathleen M Thomas, and Megan R Gunnar Institute of Child Development, University of Minnesota

Adolescence is a period of human development characterized by rapid brain development and increasing social complexity. Negative social experiences, like peer victimization, are observed to increase in adolescence and are associated with negative psychological outcomes (e.g Hawker et al., 2000). Post-institutionalized (PI) youth illustrate differential neurodevelopment in adolescence like alterations in brain volume and may be bullied more than non-adopted (NA) counterparts (Pitula et al., 2014). The current study drew a subsample of PI and NA youth (n=68; 34 PI, 34 NA) from a larger study of neurodevelopmental outcomes following early adversity to examine associations between peer victimization and brain volume. Structural MRI data was obtained and analyzed in relation to parent-reports of peer victimization experiences. Results showed significantly more victimization among PI adolescents, with later adopted adolescents experiencing more total and physical victimization than earlier adopted adolescents. Higher total victimization significantly predicted smaller hippocampal and rostral anterior cingulate volume (rACC) and higher relational victimization predicted smaller rACC. Associations between peer victimization and brain volume may indicate a structural predisposition toward victimization or rather a negative effect of victimization on brain structure. Future longitudinal research should investigate relationships between peer victimization and structural brain development to distinguish causality.

Kee-Lee Stocks
Poster: “Effects of Inhibition of Mycobacterium Tuberculosis Coenzyme a Biosynthesis on Antitubercular Activity of Pyrazinamide”
Kee-Lee K. Stocks, Dr. Yusuke Minato, Kotaro Sawai, and Dr. Anthony D. Baughn, Department of Microbiology and Immunology, University of Minnesota Medical School

The infectious disease Tuberculosis (TB), caused by Mycobacterium tuberculosis, was responsible for 1.6 million deaths globally in 2017. TB is treated using multi-drug therapy for a minimum duration of six months. Pyrazinamide (PZA) is one of the first line drugs in the multi-drug therapy yet its exact mode of action has yet to be determined. With the inclusion of PZA in treatment, the duration of treatment drops from nine months to six months by targeting the persisting populations of bacilli that are tolerant to other antitubercular agents. If we can find a way to enhance the activity of PZA, we expect treatment can be shortened further. We and others have suggested the increased coenzyme A production in M. tuberculosis antagonizes PZA activity. Thus, I hypothesize that disrupting the CoA biosynthesis pathway can potentiate PZA activity. To test this hypothesis, we used CRISPR interference (CRISPRi) to silence the transcription of various genes in the pathway. We designed sgRNA for genes within the CoA biosynthesis pathway. We then constructed CRISPRi plasmid that contained both sgRNA and dCAS9. Resultant CRISPRi plasmids were introduced into M. tuberculosis strain H37Ra. We evaluated PZA susceptibility by determining the minimal inhibitory concentration of PZA for each strain. We found that the M. tuberculosis H37Ra coaBC knockdown strain showed increased susceptibility to PZA compared to the parent strain. We conclude that with disruption to the CoA biosynthesis pathway, there is potentiation of PZA action. The other CoA pathway knockdown strains will be tested for susceptibility to determine which other pathway components represent potential targets for enhancing PZA action. A screening of a chemical compound library is also being conducted to find compounds that potentiate PZA action. Together, these explorations in molecular and chemical biology could reveal novel strategies for improving antitubercular drug action.

Mohit Uppal
Poster: “High Prevalence of Prior Contact Sports Play and Concussion Among Orthopedic and Neurosurgical Department Chairs”
Je Yeong Sone, S. Courtney-Kay Lamb M.D., Kristina Techar, Vikalpa Dammavalam, Mohit Uppal, Cedric Williams M.S.W., David Tupper Ph.D., Paul Ort M.D., Uzma Samadani M.D. Ph.D., University of Minnesota, Department of Neurosurgery

Increased understanding of the consequences of traumatic brain injury has heightened concerns about youth participation in contact sports. This study investigated the prevalence of high school and collegiate contact sports play and concussion history among surgical department chairs. A cross-sectional survey was administered to 107 orthopedic and 74 neurosurgery chairs. Responses were compared to published historical population norms for contact sports (high school 27.74%, collegiate 1.44%), football (high school 10.91%, collegiate 0.76%), and concussion prevalence (12%). High school contact sports participation was 2.35-fold higher (65.3%, p < 0.001) for orthopedic chairs and 1.73-fold higher (47.9%, p = 0.0018) for neurosurgery chairs than for their high school peers. Collegiate contact sports play was 31.0-fold higher (44.7%, p < 0.001) for orthopedic chairs and 15.1-fold higher (21.7%, p < 0.001) for neurosurgery chairs than for their college peers. Orthopedic chairs had a 4.30-fold higher rate of high school football participation (46.9%, p < 0.001) while neurosurgery chairs reported a 3.05-fold higher rate (33.3%, p < 0.001) than their high school peers. Orthopedic chairs reported a 28.1-fold higher rate of collegiate football participation (21.3%, p < 0.001) and neurosurgery chairs reported an 8.58-fold higher rate (6.5%, p < 0.001) compared to their college peers. The rate at which orthopedic (42.6%, p < 0.001) and neurosurgical (42.4%, p < 0.001) chairs reported having at least 1 concussion in their lifetime was significantly higher than the reported prevalence in the general population. The high prevalence of youth contact sports play and concussion among surgical specialty chairs affirms that individuals in careers requiring high motor and cognitive function frequently played contact sports. The association highlights the need to further examine the relationships between contact sports and potential long-term benefits as well as risks of sport-related injury.

Mohit Uppal
Poster: “A Systematic Review of Genetic Risk Factors for Traumatic Brain Injury”
Mohit Uppal, Aliya Ahmadi, Radhika Edpuganti, Duncan Hurrelbring, Timothy Suek, Daniel J. Rafter M.D., Uzma Samadani M.D. Ph.D., Department of Neurosurgery, University of Minnesota

Traumatic Brain Injuries (TBI) cause extensive morbidity and mortality with variable penetrance after exposure. The genetics of injury impacts not only exposure but also outcome. This review aims to identify and categorize genetic influencers of TBI based on pre-injury impulsivity, aggression, and ADHD-like symptom risk, short term edema and non-edema risk, and predisposition to negative long-term outcomes following TBI. 29 genes were identified: 7 as potential influencers of pre-injury risk, 6 influencing symptoms associated with short-term edema, 5 influencing symptoms associated with short-term non-edema, and 11 influencing predisposition to negative long-term outcomes. While investigations of genetic impact and influence on traumatic brain injury are still developing, using such genetic indicators has the potential to aid the diagnostic and prognostic processes involved.

Helen White
Poster: “Examining the Factor Structure of Hyperbolic Temperament in a Pregnant Sample”
Helen V. White, Megan R. Gunnar, Jed T. Elison, Colleen Doyle Faculty mentors: Megan R. Gunnar, Jed T. Elison Department: Child Psychology Institution: Institute of Child Development, University of Minnesota

The current study assesses the factor structure of hyperbolic temperament in a pregnant population (n=41) leveraging data from the Women and Infants Study of Health, Emotions, and Stress. Data collection is ongoing and we expect to have analyses on a sample of n=80 for the conference. We hypothesized that we would replicate previous work examining the factor structure underlying hyperbolic temperament in non-pregnant clinical and community samples (Hopwood et al., 2012). An exploratory factor analysis (EFA) with maximum likelihood extraction method was used to examine the factor structure of HTQ. A scree plot suggested a 5 factor solution. EFA results yielded a five-factor structure using all 32 items, all of which had pattern coefficients > .30 to only one factor. A Chi-square measure of goodness of fit showed that 5 factors were adequate to explain covariance among items (χ2 = 398.06, p = 0.028). The five factor structure that was extracted replicated results of Hopwood et al., 2012, including a hyperbolic factor, an agentic factor, a passive factor, a validation seeking factor, and a detached factor. The two factors accounting for the greatest variance were the Hyperbolic factor (percent of variance explained was 25.66%) and the Agentic factor (21.28%). Examination of the raw HTQ data showed the HTQ sum followed a normal distribution that was mildly skewed (kurtosis = -0.21). Taken together, these results provide preliminary support for utilizing a spectrum model (Tacket, 2006) to conceptualize hyperbolic temperament as a risk factor for negative mood in a pregnant population, which could have important implications for examining how prenatal stress may have an impact on the wellbeing of women during pregnancy and the outcomes of their offspring.

Kyle White
Poster: “Investigating the Binding Mechanism of EB1 to Microtubule”
Kyle White, Dr. Melissa Gardner, Department of Genetics, Cell Biology, and Development, University of Minnesota

Microtubules are long, cylindrical polymers that assist eukaryotic cells in performing a variety of critical functions including trafficking vesicular proteins to specific destinations within the cell. To accomplish this task, microtubules act with a number of microtubule-associated proteins (MAPs). One such MAP is EB1, which tip-tracks, or preferentially binds to growing tips of microtubules, which aids in targeting newly-translated proteins to precise intracellular locations. However, if EB1 is displaced from the microtubule tip, this will interfere with a cell’s ability to target vesicles to specific destinations. Importantly, an inefficient intracellular transport network is a common feature in ischemic heart disease. However, the mechanism to explain why microtubule-based transport is disrupted under conditions of ischemic oxidative stress remains a mystery. We hypothesize that microtubule structure is damaged under conditions of oxidative stress, leading to redistribution of EB1 away from the growing microtubule tip and onto locations of damage that are away from the tip. Using a novel in vitro EB1-microtubule binding assay, we found that EB1 binds the tips of both static and growing microtubules in a control, but under conditions of oxidative stress, EB1 is more evenly distributed across the entirety of microtubules. These results support our hypothesis that, under conditions of oxidative stress, EB1 is recognizing damaged or recently repaired locations along the length of the microtubule, causing it to lose its preference for the tip, and thus dramatically altering the ability of microtubules to act as effective transport systems in the cell. We anticipate that our study will aid in understanding how ischemia translates to broader heart disease. Furthermore, developing an understanding of how oxidative stress prevents EB1 from efficiently tip-tracking microtubules could lead to new targets in the treatment of ischemic heart disease.