C EBP-ALPHA EXPRESSION IN ADIPOSE-TISSUE OF GENETICALLY-OBESE ZUCKER RATS/

The adipose tissue of genetically obese Zucker rats is characterized b y coordinated tissue specific overtranscription of a subset of genes r elated to lipid storage such as Glyceraldehyde-3-Phosphase Dehydrogena se (GAPDH). We show that CCAAT/Enhancer Binding Protein alpha (C/EBP a lpha) is an activator or GAPDH proximal promoter in transiently transf ected mature rat adipocytes. C/EBP alpha mRNA levels were increased in adipose tissue but not in liver of obese as compared to lean rats at 30 days of age, i.e., when obesity is fully expressed. Nevertheless at 16 days of age, although overdevelopment of adipose tissue could be d etected in preobese rats, C/EUP alpha mRNA levels were similar whateve r the genotype. In conclusion C/ERP alpha mRNA is overexpressed in adi pose tissue of obese rats, suggesting a possible role for this factor in the activation of lipid storage-related genes in adipose tissue of obese rats. However, C/EBP alpha overexpression is not temporally rela ted to the onset of obesity. (C) 1995 Academic Press, Inc.