High osmolarity induces endoplasmic reticulum stress in renal MDCK cells.

MALVICINI, RICARDO; WEBER, KAREN; CASALI, CECILIA IRENE; FERNANDEZ TOME, MARIA DEL CARMEN

Mar del Plata, Buenos Aires, Argentina

Congreso; LI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

HIGH OSMOLARITY INDUCES ENDOPLASMIC RETICULUM STRESS IN RENALMDCK CELLSMalvicini R; Weber K; Casali CI*; Fernández M*Biología Celular y Molecular, Fac. Farmacia y Bioquímica, UBA. IQUIFIB-CONICET. CABA. Argentina.E-mail: ccasali@ffyb.uba.arRenal medullary collecting duct cells are physiologically exposed to high and variable concentrations of NaClinvolved in urinary concentrating mechanism. Despite such adverse environment, renal cells activate protective andsurvive mechanisms. In these sense, our lab demonstrated that hyperosmolarity increased lipid biosynthesis to protectmembrane integrity. It is also known that the transcription of osmoprotective genes such as organic osmolyte andurea transporters, COX2, AQP 2 and chaperones Hsp70, Osp 94 are induced. The increase in the protein synthesisrates could cause endoplasmic reticulum (ER) stress. In the present work we evaluated whether high osmolarityinduces ER stress by evaluating three ER stress markers, XBP-1, CHOP and BiP proteins. To do that, MDCK cellswere subjected to isosmolality or hyperosmolality (512 mOsm/kg H2O) for different times and the expression of ERmarkers were evaluated by RT-PCR. Results showed that there are not significant changes in BiP expression butCHOP mRNA showed an increase at early stages of NaCl treatment. XBP-1 mRNA levels showed an increase at 12hand remained constant until 48 h. These results showed that high NaCl treatment induced ER stress in MDCK cells.The XBP-1 activation could be related to the lipid synthesis increase which is necessary for membrane expansion toalleviate the ER stress. *Both are considered last authors.