Characterization of syndecan-4 expression in 3T3-F442A mouse adipocytes: Link between syndecan-4 induction and cell proliferation

Heparan sulfate proteoglycans are found on the surface of most cells. Synde can-4 is a widely expressed transmembrane heparan sulfate proteoglycan. Usi ng quantitative RNase protection assays and immunoblotting, syndecan-4 expr ession was characterized in 3T3-F442-A mouse adipoblasts. These cells exhib it dramatic changes in their biological and morphological characteristics d uring differentiation to adipocytes. During this process, the levels of syn decan-4 protein and mi expression changed dramatically. They peaked at the time when quiescent cells reentered the cell cycle before differentiation. Serum depletion-repletion also replicated the syndecan-4 mRNA induction whe n the cells were released back into proliferation, and a cycloheximide trea tment abolished the peak of induction. In addition, inhibiting syndecan-4 i nduction with antisense oligonucleotides Inhibited the proliferation of 3T3 -F442A cells. In the terminally differentiated adipocytes characterized by the loss of proliferation capability, the serum Inducibility of syndecan-4 is repressed, emphasizing the link between syndecan-4 induction in 3T3-F442 A cells and cell proliferation.