Stephen Kempson, Ph.D.
Full Member of Graduate Faculty
Department of Cellular & Integrative Physiology
Indiana University School of Medicine
635 Barnhill Drive, Room 306A
Indianapolis, Indiana 46202-5120
E-mail: skempson @ iupui.edu
Education / Training
1970, B.A. in Biological Sciences, University of Lancaster, England
1971, M.S. in Molecular Enzymology, University of Warwick, England
1975, Ph.D. in Biochemistry, University of London, England
The medulla of the kidney plays an essential role in developing the concentration gradient that is used to drive water reabsorption and concentrate the urine. The gradient is achieved by deposition primarily of NaCl and urea in the interstitial fluid that lies between medullary cells. This can create a high osmolarity that is a unique feature of the normal operation of the kidney. Both the renal epithelial cells and endothelial cells in the medulla have evolved specializations to cope with this adverse environment.
Our laboratory is interested in the regulation of membrane transport systems which allow renal cells to survive prolonged exposure to a hypertonic environment. Projects emphasize the molecular identification of specific transporters which are activated by hyperosmolarity, and the definition of the cell signals which lead to activation of those transport systems. Most recently, we have been examining the betaine transporter BGT1 which is slowly activated during prolonged hyperosmotic stress and rapidly downregulated by calcium ions.
Funding: Supported by a grant from the American Heart Association, Greater Midwest Affiliate.
Selected Recent Publications
Basham JC, Chabrerie A, and Kempson SA. Hypertonic activation of the renal betaine/GABA transporter is microtubule dependent.
Kidney Int 59: 2182-2191, 2001.
Kempson SA and Montrose MH. Regulation of renal betaine transporters.
Recent Res Devel Membrane Biol. 1: 23-32, 2002.
Bricker JL, Chu S, and Kempson SA. Disruption of F-actin stimulates hypertonic activation of the BGT1 transporter in MDCK cells.
Am J Physiol Renal Physiol 284: F930-937, 2003.
Kempson SA, Parikh V, Xi L, Chu S, and Montrose MH. Subcellular redistribution of the renal betaine transporter during hypertonic stress.
Am J Physiol Cell Physiol 285: C1091-C1100, 2003.
Kempson SA and Goodrich SP. Downregulation of betaine transport in the kidney.
Recent Res Devel Life Sci. 2: 87-97, 2004. Cat.inist
Kempson SA and Montrose MH. Invited Review: Osmotic regulation of renal betaine transport: transcription and beyond.
Pflugers Archiv - Eur J Physiol. 449: 227-234, 2004. SpingerLink
Lammers PE, Beck JA, Chu S, and Kempson SA. Hypertonic upregulation of betaine transport in renal cells is blocked by a proteasome inhibitor.
Cell Biochem Function, 23: 315-324, 2005. Wiley Interscience
Kempson SA, Beck JA, Lammers PE, Gens JS, and Montrose MH. Membrane insertion of betaine/GABA transporter during hypertonic stress correlates with nuclear accumulation of TonEBP.
Biochem Biophys Acta (BBA), 1712: 71-80, 2005. PubMed, ScienceDirect
Gentry PL and Kempson SA. Invited Review: Mechanisms of endothelial dysfunction: clues from cyclosporine.
J Pharmacol Toxicol. 1: 19-32, 2006.
Kempson SA, Edwards JM, and Sturek M. Inhibition of the renal betaine transporter by calcium ions.
Am J Physiol Renal Physiol 291(2): F305-F313, 2006.
Kempson SA, Thompson N, Pezzuto L, and Bohlen HG. Nitric oxide production by mouse renal tubules can be increased by a sodium-dependent mechanism.
Nitric Oxide, 17(1): 33-43, Aug. 2007. PubMed
Kempson SA, Edwards JM, Osborn A, and Sturek M. Acute inhibition of the betaine transporter by ATP and adenosine in renal MDCK cells.
Am J Physiol Renal Physiol 295(1): F108-F117, 2008.
Bonner JS, Anderson BM, Blevins J, and Kempson SA. Aspirin impairs transport of protective osmolytes in renal inner medullary collecting duct cells. The Open Urol Nephrol J, Vol 2: 6-10, 2009.
Anderson BA, Gordon SS, Chaidir NI, and Kempson SA. Meeting Abstract: Phosphorylation May Mediate Normal Trafficking of The Betaine/GABA Transporter (BGT1) During Hypertonic Stress in Renal Medullary Cells. The FASEB Journal 24:817.8, 2010.