Enhanced cytidylyltransferase Transcription and Translation by NS398 in hypertonic MDCK cultures.

FAVALE, NO, LEPERA, LG, GERARDI, G, STERIN-SPEZIALE, N AND FERNÁNDEZ TOME,MC

Rosario Santa Fe, Argentina

Congreso; XLII Reunión de la Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular-; 2006

SAIB

Enhanced cytidylyltransferase Transcription and Translation by NS398 in hypertonic MDCK cultures.   Favale, NO, Lepera, LG, Gerardi, G, Sterin-Speziale, N and Fernández Tome,MC Cátedra de Biología Celular. Fac. Farmacia y Bioquímica, UBA. IQUIFIB-CONICET.  nofaval@ffyb.uba.ar   Papillary collecting ducts have to work in the highest renal interstitial osmolality. We have showed that papillary cells increase their phospholipid synthesis as a protective mechanism. We also showed that renal phosphatidylcholine (PC) synthesis is regulated by cyclooxygense 2 (COX2) a survival gene. To evaluate the molecular mechanism involved, we studied PC synthesis in MDCK cultures submitted to high NaCl to mimic physiological conditions, and found that hypertonicity increases PC de novo synthesis and turnover. In order to determine if PC synthesis in MDCK is regulated by COX2 prostaglandin (PG) synthesis, as occurs in tissue, we studied PC synthesis in the absence or presence of NS398, a COX2 inhibitor. By contrast to that observed in renal tissue, NS398 did not block PC synthesis but caused its increased. In order to explain such an effect we studied the relationship between COX2 activity and CT alpha, PC rate-controlling enzyme, genetic regulation. Thus, MDCK cells were grown in physiological or hypertonic medium, with or without NS398, and PG synthesis and, CT protein and mRNA expression were determined. Under hypertonic conditions, NS398 completely blocked PG synthesis but increased PC synthesis, CT protein and mRNA suggesting that CT transcriptional and translational modulation could be due to a COX2-non prostaglandin mediated effect.