Environmental hyperosmolality regulates phospholipid biosynthesis in the renal epithelial cell line MDCK.

CECILIA I CASALI; K. WEBER; NICOLAS O. FAVALE; MARÍA DEL CARMEN FERNÁNDEZ

JLR PAPERS IN PRESS

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Año: 2013 vol. 54

0022-2275

Hyperosmolality is a key signal for renal physiology. On the one hand contributes to the differentiation of renal medullary structures and to the development of the urinary concentrating mechanism. On the other, it is a stress factor. In both cases, hyperosmolality activates processes that require an adequate extension of cellular membranes. In the present work we examined whether or not hyperosmolality regulates phospholipid biosynthesis which is needed for the membrane biogenesis in the renal epithelial cell line Madin-Darby canine kidney (MDCK). Since phospholipids are the structural determinants of all cell membranes, we evaluated their content, synthesis and regulation in MDCK cultures submitted to different hyperosmotic concentrations of NaCl, urea or both. Hyperosmolality increased phospholipid content in a concentration dependent manner. Such an effect was exclusively due to changes in NaCl concentration and occurred at the initial stage of hyperosmolar treatment concomitantly with the expression of the osmoprotective protein COX-2. The up-regulation of phospholipid synthesis by NaCl required the activation of MAPK signaling pathway. Considering that renal medullary cells are constantly exposed to high and variable NaCl, these findings are of physiological relevance showing for the first time how renal cells activate membrane synthesis to protect cellular integrity.