H+ and HCO3 are transported across tight urinary epithelia through the intercalated (or mitochondira-rich) cells. In these cells a H+ ATPase in one cell membrane is present in series with a Cl-HCO3 exchanger in the other. We found that there are two forms of these cells, one secretes H+ into the lumen while the other secretes HCO3. These two types of cells have opposite polar distribution of these two transporters. Further, we found that when animals are acid loaded, the HCO3 secreting cell changes its polarity to that of the H+ secreting cell.
The aims of this proposal is to purify the H+ ATPase from isolated kidney endocytic vesicles. The catalytic and H+ conducting sectors of this ATPase will be separately purified and reconstituted. Polyclonal and monoclonal antibodies will be raised to these proteins and the biosynthesis and degradation of the ATPase will be analysed. The polar distribution of the H+ ATPase and the Cl:HCO3 exchanger will be studied by immuno-electromicroscopy. Antibodies to the Cl:HCO3 exchanger will be raised using its probably analogues the red cell band 3. The organization of the transport proteins and their relation to the cytoskeleton will be examined before and after acid feeding. Finally, preliminary studies suggest that endocytic removal of the proton ATPase is stimulated by removal of CO2. We will measure the rate of removal of these proton pumps and the role that cell pH and calcium might play in their control. Regulation of acid base balance largely occurs through contol of H+ and HCO3 transport by the renal epithelial cell. The studies outlined in this proposal aim at clarifying the cellular and molecular mechanisms that underlie this process.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37DK020999-10
Application #
3483365
Study Section
Physiology Study Section (PHY)
Project Start
1978-07-01
Project End
1991-06-30
Budget Start
1987-07-01
Budget End
1988-06-30
Support Year
10
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Columbia University (N.Y.)
Department
Type
Schools of Medicine
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10027
Schwartz, George J; Gao, XiaoBo; Tsuruoka, Shuichi et al. (2015) SDF1 induction by acidosis from principal cells regulates intercalated cell subtype distribution. J Clin Invest 125:4365-74
Al-Awqati, Qais (2011) Terminal differentiation in epithelia: the role of integrins in hensin polymerization. Annu Rev Physiol 73:401-12
Peng, Hu; Vijayakumar, Soundarapandian; Schiene-Fischer, Cordelia et al. (2009) Secreted cyclophilin A, a peptidylprolyl cis-trans isomerase, mediates matrix assembly of hensin, a protein implicated in epithelial differentiation. J Biol Chem 284:6465-75
Al-Awqati, Qais (2008) 2007 Homer W. Smith award: control of terminal differentiation in epithelia. J Am Soc Nephrol 19:443-9
Schwaderer, Andrew L; Vijayakumar, Soundarapandian; Al-Awqati, Qais et al. (2006) Galectin-3 expression is induced in renal beta-intercalated cells during metabolic acidosis. Am J Physiol Renal Physiol 290:F148-58
Watanabe, Seiji; Tsuruoka, Shuichi; Vijayakumar, Soundarapandian et al. (2005) Cyclosporin A produces distal renal tubular acidosis by blocking peptidyl prolyl cis-trans isomerase activity of cyclophilin. Am J Physiol Renal Physiol 288:F40-7
Takito, Jiro; Al-Awqati, Qais (2004) Conversion of ES cells to columnar epithelia by hensin and to squamous epithelia by laminin. J Cell Biol 166:1093-102
Al-Awqati, Qais (2003) Terminal differentiation of intercalated cells: the role of hensin. Annu Rev Physiol 65:567-83
Schwartz, George J; Tsuruoka, Shuichi; Vijayakumar, Soundarapandian et al. (2002) Acid incubation reverses the polarity of intercalated cell transporters, an effect mediated by hensin. J Clin Invest 109:89-99
Ma, J F; Takito, J; Vijayakumar, S et al. (2001) Prostatic expression of hensin, a protein implicated in epithelial terminal differentiation. Prostate 49:9-18

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