AGING DIFFERENTIATION, AND GENE-EXPRESSION IN RAT EPIDIDYMAL PREADIPOCYTES

Ageing results in decreased replicative potential of preadipocytes, as well as reduced capacities for the lipid accumulation and increases i n lipogenic enzyme activities during differentiation of preadipocytes into fat cells. To determine whether decreased differentiation is asso ciated with decreased levels of mRNA for differentiation-dependent gen es and whether early as well as late components of the differentiation programme are affected by ageing, we measured beta-actin, alpha-tubul in, lipoprotein lipase, and glycerol-3-phosphate dehydrogenase mRNA le vels in undifferentiated and differentiated epididymal preadipocytes f rom 3-, 17-, and 24-month-old Fischer 344 rats. During ageing, diminis hed differentiation-related changes occurred in mRNAs affected early ( actin, tubulin), midway through (lipoprotein lipase), and late (glycer ol-3-phosphate dehydrogenase) in the preadipocyte differentiation proc ess. Hence, early as well as late phases of the differentiation progra mme were affected by ageing. The effects involved changes in gene tran scription or mRNA processing. Our results were not consistent with the hypothesis that age-related decreases in replication are caused by an increased tendency for cell differentiation.