| Abstract: | We have studied the structure and regulation of glycerophosphate dehydrogenase (GPD) mRNA during mouse adipocyte and muscle cell differentiation. This message has a size of 2.8 kilobases that includes a coding segment of 1050 bases and a large untranslated 3' end of about 1700 bases. There is a high degree of amino acid homology (91%) between the mouse adipocyte and rabbit muscle GPD proteins. GPD mRNA is not detected in myoblasts, but, as in adipogenesis, it is expressed upon differentiation into myotubes. The modulation of GPD mRNA by cyclic AMP analogues and tumor necrosis factor has been examined in both adipocytes and myotubes. Dibutyryl cAMP or 8-bromo-cAMP causes a large reduction of GPD mRNA levels in both cell types, with less than 20% remaining after 18 h of treatment. Tumor necrosis factor effects a dramatic and rapid reduction in GPD mRNA in fat cells and a slower but significant decrease in the level of this mRNA in muscle cells. These results indicate that GPD gene expression is linked to cell differentiation in both fat and muscle cells, and suggest certain similarities in hormonal modulation in both cell types. |
