Renal epithelial cell plasma membranes are divided into two domains whose distinct biochemical compositions reflect their individual roles. This polarity is required for vectorial solute and fluid transport in the kidney. To achieve this asymmetry, an epithelial cell must be able to establish distinct surface domains and to maintain these domains'distinct identities. The generation and maintenance of epithelial polarity is dependent upon the formation of contacts between neighboring cells, which initiates signals that activate the assembly of intercellular junctions and their associated polarization machinery. We and others have shown that adenosine monophosphate-stimulated protein kinase (AMPK) plays a key role in the formation of intercellular junctions and in the establishment of polarity. AMPK is a cellular energy sensor activated by intracellular ATP depletion that helps to protect tissues from the consequences of energy deprivation. AMPK governs numerous pathways that modulate cell growth and metabolism. Extracellular calcium plays a critical and complex role in inducing junction assembly, and we find that the calcium sensing receptor (CaSR) contributes to calcium- dependent junction assembly. We have also found that initiation of junction formation leads to inhibition of the GSK3? kinase, which regulates a number of cell differentiation and polarization signaling pathways. We wish to understand the roles that AMPK, GSK3?, the CaSR and other regulatory molecules play in the establishment and preservation of epithelial polarity under normal circumstances and in the face of pathological perturbations such as energy deprivation. We propose to determine 1) how modulation of the activities of AMPK, GSK3? and the CaSR initiate tight junction formation and influence tight junction protein expression;2) how the AMPK, GSK3? and CaSR pathways influence established junctions in intact epithelia;and 3) how loss of AMPK activity affects renal function and the susceptibility of renal tubular epithelial cells to ischemic damage. Through these studies, we will identify new regulatory targets and control points in the complex process of epithelial polarization. We will also invesigate cellular pathways involved in acute kidney injury and possible therapeutic interventions that may mitigate its severity.
Kidney epithelial cells are designed to transport salt and water, with surface membranes that are divided into two domains separated by junctions that connect neighboring cells and that control the flow of substances between them. A number of regulatory processes control the formation of these junctions. Understanding these processes is critical to understanding the normal function of the kidney and its response to injury.
|Monette, Michelle Y; Somasekharan, Suma; Forbush, Biff (2014) Molecular motions involved in Na-K-Cl cotransporter-mediated ion transport and transporter activation revealed by internal cross-linking between transmembrane domains 10 and 11/12. J Biol Chem 289:7569-79|
|Merrick, David; Bertuccio, Claudia A; Chapin, Hannah C et al. (2014) Polycystin-1 cleavage and the regulation of transcriptional pathways. Pediatr Nephrol 29:505-11|
|Stoops, Emily H; Caplan, Michael J (2014) Trafficking to the apical and basolateral membranes in polarized epithelial cells. J Am Soc Nephrol 25:1375-86|
|Stoops, Emily H; Farr, Glen A; Hull, Michael et al. (2014) SNAP-tag to monitor trafficking of membrane proteins in polarized epithelial cells. Methods Mol Biol 1174:171-82|
|Shibata, Shigeru; Arroyo, Juan Pablo; Castañeda-Bueno, María et al. (2014) Angiotensin II signaling via protein kinase C phosphorylates Kelch-like 3, preventing WNK4 degradation. Proc Natl Acad Sci U S A 111:15556-61|
|Hayashi, Hisayoshi; Tamura, Atsushi; Krishnan, Devishree et al. (2013) Ezrin is required for the functional regulation of the epithelial sodium proton exchanger, NHE3. PLoS One 8:e55623|
|Shibata, Shigeru; Rinehart, Jesse; Zhang, Junhui et al. (2013) Mineralocorticoid receptor phosphorylation regulates ligand binding and renal response to volume depletion and hyperkalemia. Cell Metab 18:660-71|
|Shibata, Shigeru; Zhang, Junhui; Puthumana, Jeremy et al. (2013) Kelch-like 3 and Cullin 3 regulate electrolyte homeostasis via ubiquitination and degradation of WNK4. Proc Natl Acad Sci U S A 110:7838-43|
|Jouret, François; Wu, Jingshing; Hull, Michael et al. (2013) Activation of the Ca²+-sensing receptor induces deposition of tight junction components to the epithelial cell plasma membrane. J Cell Sci 126:5132-42|
|Wells, Erika K; Yarborough 3rd, OrLando; Lifton, Richard P et al. (2013) Epithelial morphogenesis of MDCK cells in three-dimensional collagen culture is modulated by interleukin-8. Am J Physiol Cell Physiol 304:C966-75|
Showing the most recent 10 out of 271 publications