Ascorbic acid phosphate stimulates type IV collagen synthesis and accelerates adipose conversion of 3T3-L1 cells

We showed that the synthesis and secretion of type IV collagen, entactin, and laminin were enhanced when adipose conversion of 3T3-L1 cells at confluence was stimulated by hormones (Y. Aratani and Y. Kitagawa (1988) J. Biol. Chem. 263, 16163-16169). Ascorbic acid phosphate (Asc-P) stimulated the synthesis and secretion of type IV collagen and other collagens from both 3T3-L1 preadipocytes and adipocytes. The synthesis and secretion of laminin and entactin were not affected by Asc-P. The continuous addition of Asc-P stimulated cell growth and increased cell density at confluence 1.3-fold. Concomitantly, Asc-P remarkably accelerated the emergence of lipoprotein lipase, glycerophosphate dehydrogenase, and Oil Red O-stainable lipid droplets. These findings suggest an important role for type IV collagen in adipocyte differentiation.