Multilevel Regulation Of Protein Kinase C Delta I Alternative Splicing By Lithium Chloride

Lithium chloride (LiCI) is commonly used in treatment of mood disorders; however, its usage leads to weight gain, which promotes metabolic disorders. Protein kinase C delta (PKC delta), a serine/threonine kinase, is alternatively spliced to PKC delta I and PKG delta II in 3T3-L1 cells. We previously demonstrated that PKCol is the pre-dominantly expressed isoform in 3T3-L1 preadipocytes. Here, we demonstrate that LiCI treatment decreases PKC delta I levels, increases formation of lipid droplets, and increases oxidative stress. Hence, we investigated the molecular mechanisms underlying the regulation of PKC delta I alternative splicing by LiCl. We previously demonstrated that the splice factor SFRS10 is essential for PKCol splicing. Our results demonstrate that glycogen synthase kinase 3 beta (GSK3 beta) phosphorylates SFRS10, and SFRS10 is in a complex with long noncoding RNA NEAT1 to promote PKC delta I splicing. Using PKCS splicing minigene and RNA immunoprecipitation assays, our results demonstrate that upon LiCI treatment, NEAT1 levels are reduced, GSK3 beta activity is inhibited, and SFRS10 phosphorylation is decreased, which leads to decreased expression of PKCol. Integration of the GSK3 beta signaling pathway with the ribonucleoprotein complex of long noncoding RNA (lncRNA) NEAT1 and SFRS10 enables fine-tuning of PKC delta I expression during adipogenesis. Knowledge of the molecular pathways impacted by LiCl provides an understanding of the ascent of obesity as a comorbidity in disease management.