Bone morphogenetic protein-3b (BMP-3b) is expressed in adipocytes and inhibits adipogenesis as a unique complex.

Abstract

BACKGROUND:

Bone morphogenetic protein-3b (BMP-3b) is a member of the transforming growth factor-β (TGF-β) superfamily. BMP-3b regulates osteogenesis and has critical roles in developing embryos. BMP-3b is expressed not only in the bone and developing embryos but also in adipose tissues. However, the functions of BMP-3b in adipose tissue are still unknown.

METHODS:

BMP-3b expression was quantified in various adipose tissues and in the adipose-derived stromal-vascular fraction (SVF) and mature adipocyte fraction (AD.F) of mice. We also used 3T3-L1 preadipocytes to analyze the expression, function and molecular forms of BMP-3b. In order to determine the effects of BMP-3b on the adipogenesis of 3T3-L1 cells, BMP-3b siRNA-mediated knockdown and gene overexpression studies were performed, and a conditioned medium (CM) containing the BMP-3b protein was added to 3T3-L1 cell cultures. Adipocyte differentiation was evaluated by measuring the expression of adipogenic markers or by Oil Red O staining. The molecular form of BMP-3b that was secreted from the 3T3-L1 cells was analyzed by western blotting.

RESULTS:

BMP-3b is expressed in all adipose tissues and is expressed at higher levels in preadipocytes than in mature adipocytes. In mesenteric adipose tissue, BMP-3b expression was increased in diet-induced obesity (DIO) mice as compared with that in control mice. BMP-3b was also expressed highly in 3T3-L1 cells. We showed that siRNA-mediated knockdown of endogenous BMP-3b expression in 3T3-L1 cells enhanced adipogenesis. Conversely, overexpressing BMP-3b inhibited adipocyte differentiation. We also showed that addition of CM containing the BMP-3b protein inhibited the differentiation of 3T3-L1 cells, and that this inhibitory effect was abolished by removing BMP-3b with an anti-BMP-3b antibody. Furthermore, BMP-3b was secreted from adipocytes as a unique non-covalent complex.

CONCLUSION:

These data suggest that BMP-3b is secreted from adipocytes and is involved in adipocyte differentiation.

• Authors: J Hino, T Miyazawa, M Miyazato, K Kangawa
• Journal: International journal of obesity (2005) (Int J Obes (Lond)) Vol. 36 Issue 5 Pg. 725-34 (May 2012) ISSN: 1476-5497 [Electronic] England
• PMID: 21712809 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Growth Differentiation Factor 10

Topics

• 3T3-L1 Cells (metabolism)
• Adipocytes (metabolism)
• Adipogenesis (genetics)
• Adipose Tissue (cytology, metabolism)
• Animals
• Blotting, Western
• Gene Knockdown Techniques
• Growth Differentiation Factor 10 (metabolism)
• Mice
• Mice, Inbred C57BL
• Reverse Transcriptase Polymerase Chain Reaction
• Up-Regulation