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Roles of autocrine TGF-beta receptor and Smad signaling in adipocyte differentiation

L Choy1, J Skillington, R Derynck

  • 1Department of Growth and Development, Programs in Cell Biology and Developmental Biology, University of California at San Francisco, San Francisco, California 94143-0640, USA.

The Journal of Cell Biology
|May 3, 2000
PubMed

Insights

Transforming Growth Factor-beta (TGF-β) signaling regulates adipocyte differentiation. Smad2 and Smad3 have distinct roles, while Smad6 and Smad7 inhibit adipogenesis, paradoxically enhancing TGF-β effects.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Transforming Growth Factor-beta (TGF-β) is known to inhibit adipocyte differentiation but is expressed by adipocytes, creating a functional paradox.
  • The precise role and mechanism of TGF-β signaling in adipogenesis remain largely uncharacterized.

Purpose of the Study:

  • To investigate the function and mechanism of TGF-β signaling in adipocyte differentiation.
  • To characterize the expression and roles of TGF-β receptors and Smad proteins during adipogenesis.

Main Methods:

  • Utilized 3T3-F442A cells to study adipogenesis.
  • Analyzed mRNA levels of Smads 2, 3, 4, 6, and 7 during differentiation.
  • Employed dominant-negative interference and stable overexpression of TGF-β receptors and Smads.

Main Results:

  • TGF-β receptor availability decreased during adipogenesis.
  • Smad6 and Smad7 mRNA levels significantly decreased, while Smad2, 3, and 4 remained unchanged.
  • Inhibition of TGF-β receptor signaling enhanced differentiation; Smad3 inhibition promoted adipogenesis, while Smad2 overexpression inhibited it.
  • Overexpression of Smad6 and Smad7 blocked differentiation and enhanced TGF-β responses.

Conclusions:

  • Endogenous TGF-β signaling modulates the rate of adipogenesis.
  • Smad2 and Smad3 exhibit distinct functions in regulating adipocyte differentiation.
  • Smad6 and Smad7 function as negative regulators of adipogenesis, enhancing TGF-β effects despite their inhibitory nature.

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