My ultimate goal is to become a fully independent principal investigator with a basic science laboratory examining the molecular physiology of renal ion transport. After completing 6 years of training with Dr. Steven Herbert at 3 different institutions, I became an Assistant Professor at the University of Chicago. I have studied the regulation of the rat thiazide-sensitive sodium chloride cotransporter (rNCC) by glycosylation and phosphorylation for that period of time. I have demonstrated that rNCC is capable of being PKC phosphorylated in vitro, rNCC is functionally inhibited by PKC and there is a significant increase in baseline function and surface expression of rNCC with mutation of consensus PKC phosphorylation sites. With the support of this Career Development Award, the University of Chicago Department of Medicine, and my mentors, Dr. Herbert and Dr. Chang, I hope to continue to progress towards my long term goal. NCC is the site of action of one of the most commonly prescribed anti-hypertensive medications and plays a key role in divalent cation handling, yet we know little about it's regulation. This proposal will test the hypothesis that PKC and WNK4 kinase play a key role in regulation of NCC, predominantly by phosphorylation of serine and threonine residues resulting in decreased surface expression. The first specific aim will seek to define the role and mechanisms of WNK4 kinase, PKC and PKA in regulating the activity and surface expression of NCC. The second specific aim will seek to explore the physiological and hormonal regulation of the cotransporter and kinases, the physiological role of the cotransporter in divalent ion handling and the mechanisms underlying these processes. This investigation of the regulation of this effector of blood pressure and calcium homeostasis will provide invaluable insight into the pathogenesis of dysregulation of these homeostatic mechanisms.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Clinical Investigator Award (CIA) (K08)
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Special Emphasis Panel (ZDK1-GRB-R (J1))
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Rankin, Tracy L
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University of Chicago
Internal Medicine/Medicine
Schools of Medicine
United States
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Chávez-Canales, María; Arroyo, Juan Pablo; Ko, Benajmin et al. (2013) Insulin increases the functional activity of the renal NaCl cotransporter. J Hypertens 31:303-11
Hoover, Robert S (2011) Angiotensin II: a candidate for an aldosterone-independent mediator of potassium preservation during volume depletion. Kidney Int 79:377-9
Ko, Benjamin; Cooke, Leslie L; Hoover, Robert S (2011) Parathyroid hormone (PTH) regulates the sodium chloride cotransporter via Ras guanyl releasing protein 1 (Ras-GRP1) and extracellular signal-regulated kinase (ERK)1/2 mitogen-activated protein kinase (MAPK) pathway. Transl Res 158:282-9
Arroyo, Juan Pablo; Lagnaz, Dagmara; Ronzaud, Caroline et al. (2011) Nedd4-2 modulates renal Na+-Cl- cotransporter via the aldosterone-SGK1-Nedd4-2 pathway. J Am Soc Nephrol 22:1707-19
Ko, Benjamin; Kamsteeg, Erik-Jan; Cooke, Leslie L et al. (2010) RasGRP1 stimulation enhances ubiquitination and endocytosis of the sodium-chloride cotransporter. Am J Physiol Renal Physiol 299:F300-9
Ko, Benjamin; Hoover, Robert S (2009) Molecular physiology of the thiazide-sensitive sodium-chloride cotransporter. Curr Opin Nephrol Hypertens 18:421-7
Ko, Benjamin; Joshi, Leena M; Cooke, Leslie L et al. (2007) Phorbol ester stimulation of RasGRP1 regulates the sodium-chloride cotransporter by a PKC-independent pathway. Proc Natl Acad Sci U S A 104:20120-5