The hypothesis guiding these studies is that the character and specificity of cell signaling systems is determined by structural proteins that organize multiple signaling proteins into discrete complexes in the cell. Some components are common to many signaling systems, while others may be unique. These studies will focus on the interaction of the extracellular Ca-sensing receptor (CaR) and filamin (ABP-280), a cytoskeletal protein, in renal epithelial cells with emphasis on MTAL and INCO cells. The CaR is a G protein-coupled receptor that responds to Ca and other polycations to regulate PTH secretion by the parathyroid glands and Ca, NaCI, KCl, and H20 transport in the kidney. The CaR has unique signaling properties that are not fully explained by its activation of Gi- and Gq-dependent signaling pathways. In an effort to identify potential scaffolding proteins for the signaling systems controlled by the CaR and identify new signaling pathways through which it might act, we used the CaR intracellular C-terminus as """"""""bait"""""""" to screen a human kidney cDNA library using the yeast two hybrid approach. We found that the CaR interacts with filamin (ABP-280), a 280 kDa actin-binding cytoskeletal protein. Filamin also binds to variety of other signaling molecules including SEKI (MKK4), caveolin, the dopamine 02 receptor, Rho GTPases, SMADs and a- and Beta integrins, suggesting that it can act as a scaffold. The goals of this application are to define the interaction of the CaR and filamin and to understand how this interaction affects the signaling functions of the CaR in renal epithelial cells.
The specific aims are:
Aim 1) Characterize the interaction of the C-terminus of the CaR with fliamin using the yeast two hybrid system and mammalian cells;
Aim 2) Determine the functional significance of the CaR-filamin interaction by analysis of CaR-stimulated signals in cells that lack filamin and by specific disruption of CaR-filamin association;
Aim 3) Establish the subcellular pattern of distribution of the CaR in renal epithelial cells and determine if the interaction of the CaR with filamin contributes to the localization of the CaR in renal epithelial cells;
Aim 4) Identify the smallest portion of filamin that can reconstitute signaling by the CaR in filamin-null cells, and then identify additional proteins that interact with that fragment. These studies will test the hypothesis that the interaction of filamin and the CaR is important for appropriate cell signaling by the CaR and that filamin acts as a scaffolding protein to organize the signaling pathway(s) regulated by the CaR.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK059985-02
Application #
6640447
Study Section
General Medicine B Study Section (GMB)
Program Officer
Ketchum, Christian J
Project Start
2002-07-01
Project End
2006-04-30
Budget Start
2003-07-01
Budget End
2004-04-30
Support Year
2
Fiscal Year
2003
Total Cost
$219,301
Indirect Cost
Name
Case Western Reserve University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
077758407
City
Cleveland
State
OH
Country
United States
Zip Code
44106
Tyler Miller, R (2013) Control of renal calcium, phosphate, electrolyte, and water excretion by the calcium-sensing receptor. Best Pract Res Clin Endocrinol Metab 27:345-58
Cha, Seung-Kuy; Huang, Chunfa; Ding, Yaxian et al. (2011) Calcium-sensing receptor decreases cell surface expression of the inwardly rectifying K+ channel Kir4.1. J Biol Chem 286:1828-35
Huang, Chunfa; Miller, Richard Tyler (2010) Novel Ca receptor signaling pathways for control of renal ion transport. Curr Opin Nephrol Hypertens 19:106-12
Sindic, Aleksandra; Huang, Chunfa; Chen, An-Ping et al. (2009) MUPP1 complexes renal K+ channels to alter cell surface expression and whole cell currents. Am J Physiol Renal Physiol 297:F36-45
Drawz, Paul E; Miller, R Tyler; Sehgal, Ashwini R (2008) Predicting hospital-acquired acute kidney injury--a case-controlled study. Ren Fail 30:848-55
Plata, Consuelo; Sussman, Caroline R; Sindic, Aleksandra et al. (2007) Zebrafish Slc5a12 encodes an electroneutral sodium monocarboxylate transporter (SMCTn). A comparison with the electrogenic SMCT (SMCTe/Slc5a8). J Biol Chem 282:11996-2009
Huang, Chunfa; Miller, R Tyler (2007) The calcium-sensing receptor and its interacting proteins. J Cell Mol Med 11:923-34
Huang, Chunfa; Miller, R Tyler (2007) Regulation of renal ion transport by the calcium-sensing receptor: an update. Curr Opin Nephrol Hypertens 16:437-43
Tandon, R; Levental, I; Huang, C et al. (2007) HIV infection changes glomerular podocyte cytoskeletal composition and results in distinct cellular mechanical properties. Am J Physiol Renal Physiol 292:F701-10
Huang, Chunfa; Sindic, Aleksandra; Hill, Ceredwyn E et al. (2007) Interaction of the Ca2+-sensing receptor with the inwardly rectifying potassium channels Kir4.1 and Kir4.2 results in inhibition of channel function. Am J Physiol Renal Physiol 292:F1073-81

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