Up-regulation of adipogenin, an adipocyte plasma transmembrane protein, during adipogenesis.
Until now, the various proteins highly expressed in adipose tissues have been identified and characterized by traditional gene cloning techniques. However, methods of computer analysis have been developed to compare the levels of expression among various tissues, and genes whose expression levels differ significantly between tissues have been found. Among these genes, we report on the possible function of a new adipose-specific gene, showed higher expression in adipose tissue through 'Search Expression' on Genome Institute of Norvartis Research Foundation (GNF) SymAtlas v0.8.0. This database has generated and analyzed gene expression of each gene in diverse samples of normal tissues, organs, and cell lines. This newly discovered gene product was named adipogenin because of its role in stimulating adipocyte differentiation and development. Adipogenin mRNA was highly expressed in four different fat depots, and exclusively expressed in adipocytes isolated from adipose tissues. The level of adipogenin mRNA was up-regulated in the subcutaneous and visceral adipose tissues of mice fed a high-fat diet compared to those on the control diet. The expression of adipogenin mRNA is dramatically elevated during adipocyte differentiation of 3T3-L1 cells. Troglitazone, which up-regulated peroxisome proliferators-activated receptor gamma2 (PPAR-gamma2) expression, increased adipogenin mRNA expression, although this gene was down-regulated by retinoic acid. Confocal image analyses of green-fluorescent protein-adipogenin (pEGFP-adipogenin) transiently expressed in 3T3-L1 adipocytes showed that adipogenin was strictly localized to membranes and was absent from the cytosol. Moreover, small interfering RNA (siRNA) mediated a reduction of adipogenin mRNA in 3T3-L1 cells and blocked the process of adipocyte differentiation. These results indicate that adipogenin, an adipocyte-specific membrane protein, may be involved with adipogenesis, as one of the regulators of adipose tissue development.
Hong
Yeon-Hee
YH
Department of Food Production Science, Faculty of Agriculture, Shinshu University, Nagano-ken 399-4598, Japan.
Hishikawa
Daisuke
D
Miyahara
Hisae
H
Tsuzuki
Hiroaki
H
Nishimura
Yukihiko
Y
Gotoh
Chizu
C
Choi
Ki-Choon
KC
Hokari
Yu
Y
Takagi
Yuji
Y
Lee
Hong-Gu
HG
Cho
Kwang-Keun
KK
Roh
Sang-Gun
SG
Sasaki
Shinichi
S
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D050156:Adipogenesis; D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D003593:Cytoplasm / Q000737:chemistry*; D030541:Databases, Genetic; D004036:Diet, Atherogenic; D018507:Gene Expression Regulation, Developmental; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
D008565:Membrane Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C495823:SMAF1 protein, mouse