CONICET | Buscador de Institutos y Recursos Humanos

Papillary collecting ducts have to work in the highest renal interstitial osmolarity, and increase their phosphatidylcholine (PC) synthesis as a protective mechanism. PC synthesis occurs by Kennedy pathway where CCTa is the regulatory enzyme. CCTa is an amphitropic enzyme, but in most cell lines it has been localized predominantly in the nucleus. On the other hand we have demonstrated that hypertonicity induces lamin A/C distribution to nucleoplasm speckle. In the present work we examined how hypertonic medium affects the nuclear distribution of CCTa in MDCK cells. We also evaluated the relationship between the lamin A/C speckles and intranuclear CCTa. Confocal microscopy showed that under hypertonic conditions CCTa colocalize with speckles. To evaluate if this colocalization involves protein interaction, ClNa-TritonX-100 extraction and Immunoprecipitation assays were performed. Both experiments demonstrated CCTa interaction with Lamin A/C. Silencing of Lamin A/C causes decreases in lamin A/C speckles number and CCTa redistribution to soluble nuclear matrix. Results herein demonstrate that hypertonicity induces CCTa redistribution from soluble nuclear matrix to nuclear speckles, and this distribution dependent on lamin A/C scaffold. We propose that under hypertonic condition CCTa interact with lamin A/C-speckles thus establishing two different intranuclear enzyme pools.