title: Role of claudins in renal calcium handling.
abstract: Paracellular channels occurring in tight junctions play a major role in transepithelial ionic flows. This pathway includes a high number of proteins, such as claudins. Within renal epithelium, claudins result in an ionic selectivity in tight junctions. Ascending thick limb of loop of Henle (ATLH) is the most important segment for calcium reabsorption in renal tubules. Its cells create a water-proof barrier, actively transport sodium and chlorine through a transcellular pathway, and provide a paracellular pathway for selective calcium reabsorption. Several studies have led to a model of paracellular channel consisting of various claudins, particularly claudin-16 and 19. Claudin-16 mediates cationic paracellular permeability in ATLH, whereas claudin-19 increases cationic selectivity of claudin-16 by blocking anionic permeability. Recent studies have shown that claudin-14 promoting activity is only located in ATLH. When co-expressed with claudin-16, claudin-14 inhibits the permeability of claudin-16 and reduces paracellular permeability to calcium. Calcium reabsorption process in ATLH is closely regulated by calcium sensor receptor (CaSR), which monitors circulating Ca levels and adjusts renal excretion rate accordingly. Two microRNA, miR-9 and miR-374, are directly regulated by CaSR. Thus, miR-9 and miR-374 suppress mRNA translation for claudin-14 and induce claudin-14 decline.
authors: Departamento de Fisiología, Universidad del Salvador, Ciudad Autónoma de Buenos Aires, CABA, Argentina. Electronic address: armando.negri@gmail.com.
authors: Armando Luis
authors: AL
authors: Negri
mesh_terms: D000818:Animals; D000838:Anions / Q000378:metabolism; D001693:Biological Transport, Active / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002412:Cations / Q000378:metabolism; D002463:Cell Membrane Permeability; D002712:Chlorides / Q000378:metabolism; D057167:Claudins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008138:Loop of Henle / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000502:physiology; D014176:Protein Biosynthesis; D020033:Protein Isoforms / Q000502:physiology; D044169:Receptors, Calcium-Sensing / Q000502:physiology; D065608:Renal Reabsorption / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D019108:Tight Junctions / Q000502:physiology; D057900:Transcytosis / Q000502:physiology
chemical_list: D000838:Anions; C095550:CASR protein, human; D002412:Cations; D002712:Chlorides; D057167:Claudins; C587995:MIRN374 microRNA 374, human; C541874:MIRN92 microRNA, human; D035683:MicroRNAs; D020033:Protein Isoforms; D044169:Receptors, Calcium-Sensing; D012964:Sodium; D002118:Calcium
keywords: Calcium sensor receptor; Claudinas; Claudins; Paracellular pathway; Reabsorción renal de calcio; Receptor sensor de calcio; Renal calcium reabsorption; Vía paracelular