Division Head: Metabolic and Systems Biology
Our research focuses on the hormone/parascrine natriuretic peptide family and their cognate guanylyl cyclase (GC)-A and GC-B receptors. These signaling pathways regulate blood pressure, bone growth, reproduction, metabolism and other functions. Over the past few years, we have worked on the four natriuiretic peptide related research areas described below.
Andrea Yoder identified and characterized novel phosphorylation sites in rat and human forms of GC-A and GC-B by mass spectrometry (Yoder et al, Biochemistry, 2010) as well as by a novel alanine/glutamate mutagenesis functional screen (Yoder et al, PLoS One, 2012). In collaboration with Dr. Laurinda Jaffe’s group, we are extending this work by investigating the possibility that luetineizing hormone inhibits GC-B in the mouse oocyte by dephosphorylation (Robinson et al, Developmental Biology, 2012).
Paula Bryan developed a Diamond ProQ/SYPRO RUBY method for measuring the phosphate/protein levels of unlabeled GC-A and GC-B endogenously expressed in cells and tissues (Bryan et al, Biochemistry, 2006) and used it to show that GC-A activity is reduced in response to experimental heart failure in mice by downregulation not dephosphorylation (Bryan et al, AJP, 2007). In related work, Deborah Dickey observed that GC-B is the major guanylyl cyclase receptor in the mouse heart and that GC-A activity, but not GC-B activity, is reduced in ventricles of mice with experimentally-induced heart failure (Dickey et al., Endocrinology, 2007). Importantly, she extended these findings to failed human hearts (Dickey et al., JMCC, 2012).
We also characterized the structure/function relationship of natriuretic peptides and determined how natural or synthetic mutations affect the ability of the peptides to activate their cognate receptors or to be proteolytically degraded. For example, Andrea Yoder showed that a single Arg to Gly mutation in CNP that causes dwarfism decreases the ability of the peptide to bind and activate GC-B due to losses in steric and ionic contacts (Yoder et al., Peptides, 2008). Deborah Dickey designed chimeric bifuntional peptides as potential therapeutics for congestive heart failure and hypertension that activate both GC-A and GC-B and identified two separate triplet regions that control receptor specificity (Dickey et al. JBC, 2008). Drs. Dickey and Yoder also determined that a human frameshift mutation in ANP associated with familial atrial fibrillation increased the half life of the peptide by reducing its ability to be proteolytically degraded (Dickey et al., JBC, 2009). Finally, Dr. Dickey determined that BNP is not degraded by neutral endopepidase as hypothesized by others (Dickey and Potter, Biochem. Pharm., 2010) and that the designer therapeutic peptide, CD-NP, is resistant to proteolytic degradation (Dickey and Potter, JMCC, 2011).
When we began studying ATP regulation of GC-A and GC-B, the activation model was that natriuretic peptide binding allowed ATP to bind the kinase homology domain, which caused the two catalytic domains to come together to form an active site (Chinkers et al, JBC, 1991). In this model, ATP increases maximal velocity and was absolutely required for enzyme activation. However, Laura Antos showed that ATP is not required for activation of GC-A and GC-B if the receptors are phosphorylated and assayed for short periods of time (Antos et al., JBC, 2005). She later demonstrated that ATP reduces the Km of endogenously expressed enzymes without affecting maximal velocity if assayed for longer periods of time (Antos and Potter, AJP, 2007). Jerid Robinson identified the first intracellular inhibitor of GC-A and GC-B (Robinson et al. BJP, 2011) and determined that GTP increases the affinity of the allosteric site for ATP, which demonstrated reciprocal regulation between the allosteric and catalytic sites (Robinson and Potter, JBC, 2011). He went on to show that ATP reduces that Km for these enzymes by competing with GTP for the allosteric site in the catalytic domain and that the structural requirements for binding the allosteric and catalytic sites are unique. He also showed that both enzymes are asymmetric homodimers, not symmetric dimers as had been previously suggested (Robinson and Potter, Science Signaling, 2012). Finally, he showed that a single residue mutation in the catalytic domain of GC-B causes skeletal overgrowth by locking the enzyme in a constutively active state that is immune to desensitization (Robinson et al., Bone, 2013). These experiments identified a previously unidentified drug site and completely changed the activation model for GC-A and GC-B.
Lincoln Potter Lab
Jerid Robinson and family after the successful defense of his thesis titled “Activation and Inhibition Mechanisms of Membrane Guanylyl Cyclases” on April 3, 2013.
Deb, Xiaoxiao, Jerid and Lincoln at Al’s Breakfast in Dinkytown (February 2011)
|Holiday Gathering 2011|
Andrea and Dad after Ph.D. defense in September 2010
William McDowell presenting his poster at the University of Minnesota Undergraduate Research Day Event.
William will begin his medical training at the University of Iowa Medical School in the fall of 2014.
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Robinson, J, W, Dickey, D.M., Miura, K., Michigami, T., Ozono, K. and Potter, L. R. (2013) A Human Skeletal Overgrowth Mutation Increases Maximal Velocity and Blocks Desensitization of Guanylyl Cyclase-B, Bone, July 1, 2013
Robinson, J. W. and Potter, L. R. (2012) Guanylyl Cyclase A and B Are Asymmetric Dimers that Are Allosterically Activated by ATP Binding to the Catalytic Domain, Science Signaling 5, 240, ra65. This article is discussed by the accompanying perspective titled, “Allosteric Regulation of Nucleotidyl Cyclases: An Emerging Pharmacological Target" by R. Seifert and K. Y. Beste, Science Signaling 5, 240, pg37
Robinson, J. W., Zhang, M., Shuhaibar, L. C., Norris, R. P., Geerts, A., Wunder, F., Eppig, J. J., Potter, L. R. and Jaffe, L. A. (2012) Luteinizing Hormone Reduces the Activity of the NPR2 Guanylyl Cyclase in Mouse Ovarian Follicles, Contributing to the Cyclic GMP Decrease that Promotes Resumption of Meiosis in Oocytes, Developmental Biology, 366, 308-316
Yoder, A. R., Robinson, J. W., Dickey, D. M, Andersland, J. Rose, B. A., Stone, M. D., Griffin, T. J. and Potter, L. R. (2012) A Functional Screen Provides Evidence for a Conserved Regulatory, Juxtamembrane Phosphorylation Site in Guanylyl Cyclase A and B, PLoS ONE 7(5): e36747.doi.1371/journal.pone.0036747
Dickey, D. M., Dries, D. L., Margulies, K. B. and Potter, L. R. (2012) Guanylyl Cyclase-A and -B Activities in Ventricles and Cardiomyocte from Failed and Non-failed Human Hearts, J. Molecular and Cellular Cardiology, 52, 727-32.
Potter, L. R. (2011) Guanylyl cyclase structure, function and regulation. Cellular Signaling, 23, 1921-26
Robinson, J. W. and Potter, L. R. (2011) ATP potentiates competitive inhibition of guanylyl cyclase A and B by the staurosporine analog, Gö6976: reciprocal regulation of ATP and GTP binding. J. Biol. Chem., 286, 33841-4
Dickey, D. M. and Potter, L. R. (2011) ProBNP(1-108) is resistant to degradation and activates guanylyl cyclase-A with reduced potency. Clinical Chemistry, 57:9, 1272-78
Potter, L. R. (2011) Natriuretic peptide metabolism, clearance and degradation. FEBSJ., 278, 1808-1
Dickey, D. M., Flora, D. R. and Potter, L. R. (2011) Antibody tracking demonstrates cell type-specific and ligand-independent internalization of guanylyl cyclase a and natriuretic peptide receptor C. Molecular Pharmacology, 80, 155-62
Dickey, D. M. and Potter, L. R. (2011) Dendroaspis natriuretic peptide and the designer natriuretic peptide, CD-NP, are resistant to proteolytic inactivation. J. Molecular and Cellular Cardiology, 51, 67-71
Robinson, J. W. Lou, Xiaoying and Potter, L. R. (2011) The indolocarbazole, Gö6976, inhibits guanylyl cyclase-A and -B. British. J. Pharmacology, 164, 499 506.
Potter, L. R. (2011) Regulation and therapeutic targeting of peptide-activated receptor guanylyl cyclases. Pharmacology and Therapeutics, 130, 71-82
Ralat, L., Guo, Q, Ren, M., Funke, T. Dickey, D. M., Potter, L. R. and Tang, W-J (2011) Insulin-degrading enzyme modulates the natriuretic peptide-mediated signaling response. J. Biol. Chem., 286, 4670-9
Yoder, A. R., Stone, M. D., Griffin, T. J. and Potter, L. R. (2010) Mass spectrometric identification of phosphorylation sites in guanylyl cyclase A and B. Biochemistry, 49, 10137-45
Dickey, D. M. and Potter, L. R. (2010) Human B-type natriuretic peptide is not degraded by meprin A. Biochem. Pharmacol. 80, 1007-11
Dickey, D. M., Barbieri, K. A., McGuirk, C. M. and Potter, L. R. (2010) Arg13 of B type natriuretic Peptide reciprocally modulates binding to guanylyl cyclase but not clearance receptors. Molecular Pharmacology, 78, 431-5
Flora, D. R. and Potter, L. R. (2010) Prolonged atrial natriuretic peptide exposure stimulates guanylyl cyclase-A degradation. Endocrinology, 151, 2769-76
Dickey, D. M. Yoder, A. R. and Potter, L. R. (2009) A familial mutation renders atrial natriuretic Peptide resistant to proteolytic degradation. J. Biol. Chem. 284, 19196-202
Dickey, D. M, Burnett, J. C, and Potter, L. R. (2008) Novel bifunctional natriuretic peptides as potential therapeutics. J. Biol. Chem. 283, 3500-9