Intranuclear Speckle Localization Of Cytidylyltransferase Alpha Serves As A Regulatory Mechanism

FAVALE NO; SANTACREU B; GERARDI G; STERIN-SPEZIALE NB

Puerto Madryn, Chubut, Argentina

Congreso; XLVI Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2010

SAIB

CCTa is an amphitropic enzyme, but in most cell lines it has been localized predominantly in the nucleus. We have demonstrated that hypertonicity (stimulus that evokes differentiation) induces lamin A/C distribution to nucleoplasmic speckles and CCTa colocalizes with these intranuclear structures. In the present work we evaluated the importance of CCTa intranuclear redistribution and its relationship with enzyme activity and PtdCho synthesis. Silencing of Lamin A/C caused decrease in CCTa speckles number and an increase in CCTa activity. To evaluate CCTa speckle dynamics, cells were treated with oleic acid. Treatment was able to mobilize CCTa outside of speckles and was redistributed to nuclear envelope. Interestedly CCTa relocalization occurred only in MDCK cells subjected to hypertonicity but not in control cells. Oleic acid stimulus induced higher increase in PtdCho synthesis in control cells than hypertonic treated cells. No changes were observed in CCTa activity. Results herein demonstrate that oleic acid induces CCTa redistribution which occurs only in hypertonicity subjected MDCK cell, suggesting that in differentiated cells, CCTa-speckles are necessary for its re-localization. Under hypertonic condition intranuclear CCTa distribution in nuclear speckles could serve as a localized platform that facilitates CCTa mobilization.