I am driven to expand our knowledge of the structural basis of regulation of the sarcoplasmic reticulum Ca2+ release channel, ryanodine receptor. This work is also partnered by a translational goal to develop high-throughput screening (HTS) methods for discovery of RyR targeted compounds that relieve the deleterious SR Ca2+ leak that contributes to the pathology of several severe diseases (sarcopenia, muscular dystrophy, heart failure, diabetes, Alzheimer's disease). Both projects utilize a FRET based toolkit that involves targeting a donor fluorophore to the cytoplasmic assembly of RyR in skeletal or cardiac SR membranes via fluorescently-labeled FKBP12.6, and then measuring time-resolved FRET in the presence of fluorescently-labeled calmodulin. Compared to analysis of FRET by steady-state fluorescence (only resolves a single, average distance), analysis of FRET data by time-resolved fluorescence resolves multiple distance distributions – i.e. structural states – and also the population of probes in each structural state. Therefore, TR-FRET-based measurements have much higher structural resolution than fluorescence intensity measurements of FRET. As I have recently demonstrated in a recent article published in J Biol Chem. (Rebbeck et al., 2016a), TR-FRET analysis has significantly matured, enabling me to resolve for the CaM-RyR complex: (1) the degree of occupancy of each CaM binding site, (2) multiple distances, and (3) their population distribution. I have directly applied this technique to distinguish subtle and dramatic changes in the CaM-RyR complex due to the presence of S100A1 (another RyR fine-tune modulator), cytoplasmic Ca2+, and disease associated mutations in CaM. Furthermore, incorporation of a plate reader with the rapid (ns) and high precision properties of our FRET toolkit has enabled HTS of small compound libraries for modulators of the ryanodine receptor. The initial results of this exciting project show great promise for identifying RyR modulators, as shown in our manuscript recently accepted for publishing by J. Biomol. Screen (Rebbeck et al., 2016b).
In addition to my passion to contribute to our understanding of RyR regulation and identification of potential RyR-targeted therapies, I am dedicated to kindling the passion of potential and early career researchers for medical research by one-on-one mentorship. Currently, I am directly supervising two such dedicated undergraduate students, Megan Ryan and Claire Haskin.
Honors and Recent Awards:
2010 – 2014 Australian Postgraduate Award
2014 – 2016 American Heart Association Mid-West Affiliate 2014 Postdoctoral Fellowship
2016 – 2018 American Heart Association Mid-West Affiliate 2016 Postdoctoral Fellowship
2015 Barnum Travel Award, provided by Dept. of Biochemistry, Molecular Biology and Biophysics, University of Minnesota to attend the Biophysical Society 57th Annual Meeting in Baltimore, MD
2015 Gordon Conference Early-Career Travel Award to participate in the Gordon Conference on Muscle: Excitation Contraction Coupling in Newry, ME, USA
2015 Postdoctoral Poster Prize at the Gordon Conference on Muscle: Excitation Contraction Coupling in Newry, ME, USA
2016 International Society for Heart Research North American Section Travel Award, provided by ISHR-NAS to participate in the 2016 ISHR World Congress, Buenos Aires, Argentina.
Rebbeck RT, Y Karunasekara, EM Gallant, PG Board, NA Beard, MG Casarotto, and AF Dulhunty. 2011. The β1a subunit of the skeletal DHPR binds to skeletal RyR1 and activates the channel via its 35-residue C-terminal tail. Biophys J 100:922-30
Karunasekara Y1, RT Rebbeck1, LM Weaver, PG Board, AF Dulhunty2 and MG Casarotto2. 2012. An a-helical C-terminal tail segment of the skeletal L-type Ca2+ channel β1a subunit activates ryanodine receptor type 1 via a hydrophobic surface. FASEB J. 26(12):5049-59. 1equal first author contribution; 2equal senior author contribution.
Rebbeck RT, Y Karunasekara, PG Board, NA Beard, MG Casarotto and AF Dulhunty. 2014. Skeletal muscle excitation-contraction coupling: Who are the dancing partners? Int J Biochem Cell Biol. 48:28-38
Hernandez-Ochoa EOΔ, RO OlogoΔ, RT RebbeckΔ, AF Dulhunty and MF Schneider. 2014. β1a490-508, a 19-residue peptide from C-terminal tail of Cav1.1 β1a subunit potentiates voltage-dependent calcium release in adult skeletal muscle fibers. Biophys J. 106(3); 535-47. Δcontributed equally to this work.
Rebbeck RT, H Willemse, L Groom, MG Casarotto, PG Board, NA Beard, RT Dirksen and AF Dulhunty. 2015. Regions of ryanodine receptors that influence activation by the dihydropyridine receptor β1a subunit. Skelet Muscle. 5:23.
Rebbeck RT, FR Nitu, D Rohde, P Most, DM Bers, DD Thomas, RL Cornea. 2016a. S100A1 Protein Does Not Compete with Calmodulin for Ryanodine Receptor Binding but Structurally Alters the Ryanodine Receptor Calmodulin Complex. J Biol Chem. 291(30): 15896-907.
Rebbeck, RT, MM Essawy, FR Nitu, DD Thomas, DM Bers, and RL Cornea. 2016b. High-throughput screens to discover small molecule modulators of ryanodine receptor calcium release channels. J Biomol Screen: DOI: 10.1177/1087057116674312
Upcoming Conference Presentations:
2017 Biophysical Society 61th Annual Meeting in New Orleans, Louisiana, USA, February 2017