Biphasic expression of lipin suggests dual roles in adipocyte development.

The identification of gene mutations that cause lipodystrophies, conditions characterized by a lack of normal adipose tissue, has revealed new proteins that play a role in adipocyte biology. Lipin is one such protein identified in a lipodystrophic mouse strain and found to be critical for normal adipocyte differentiation. Interestingly, lipin displays a biphasic expression pattern in adipocytes, with peaks of expression at two points during adipogenesis--a transient induction in preadipocytes prior to expression of peroxisome proliferator-activated receptor gamma, and a second wave of expression in mature adipocytes. Thus, lipin appears to have critical roles in both adipocyte differentiation and in the function of mature adipocytes.