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TGF‐β blocks early but not late differentiation‐specific gene expression and morphologic differentiation of 3T3 T proadipocytes
Author(s) -
Sparks Rodney L.,
Allen Blake J.,
Strauss Ethan E.
Publication year - 1992
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041500318
Subject(s) - cellular differentiation , gene expression , transforming growth factor , microbiology and biotechnology , biology , gene , expression (computer science) , growth differentiation factor , genetics , computer science , bone morphogenetic protein , programming language
Abstract Transforming growth factor‐β (TGF‐β) inhibits morphologic differentiation of BALB/c 3T3 T cells as well as other proadipocyte models. Our prior studies suggested that TGF‐β may act only during the early stages of differentiation induction. However, we did not determine whether TGF‐β was differentially effecting expression of any of the various differentiation‐specific genes or if it could cause down‐regulation of these genes in differentiated cells. Therefore, in the current study we tested the effects of exogenous TGF‐β (0.01–5.0 ng/ml) on morphologic differentiation and on differentiation‐dependent gene expression (Northern and slot blot analyses) at various times during differentiation. When induced to differentiate, 3T3 T cells first undergo predifferentiation growth arrest and from this state molecular, biochemical, and morphological differentiation proceeds. Here it was found that when added prior to the onset of differentiation, TGF‐β was a potent inhibitor of morphologic differentiation as well as of the expression of differentiation‐specific genes such as lipoprotein lipase (LPL) and glycerol‐3‐phosphate dehydrogenase (GPD). However, once morphologic differentiation began, TGF‐β was ineffective in blocking differentiation. In addition, exposure of fully differentiated cells to TGF‐β for up to 72 hours caused no decrease of differentiation‐specific genes and even a 7‐day treatment caused no morphologic dedifferentiation. Tumor necrosis factor also had no detectable effect on fully differentiated cells.