Proteome analysis of adipocyte lipid rafts reveals that gC1qR plays essential roles in adipogenesis and insulin signal transduction.
Since insulin receptors and their downstream signaling molecules are organized in lipid rafts, proteomic analysis of adipocyte lipid rafts may provide new insights into the function of lipid rafts in adipogenesis and insulin signaling. To search for proteins involved in adipocyte differentiation and insulin signaling, we analyzed detergent-resistant lipid raft proteins from 3T3-L1 preadipocytes and adipocytes by 2-DE. Eleven raft proteins were identified from adipocytes. One of the adipocyte-specific proteins was globular C1q receptor (gC1qR), an acidic 32 kDa protein known as the receptor for the globular domain of complement C1q. The targeting of gC1qR into lipid rafts was significantly increased during adipogenesis, as determined by immunoblotting and immunofluorescence. Since the silencing of gC1qR by small RNA interference abolished adipogenesis and blocked insulin-induced activation of insulin receptor, insulin receptor substrate-1 (IRS-1), Akt, and Erk1/2, we can conclude that gC1qR is an essential molecule involved in adipogenesis and insulin signaling.
Kim
Ki-Bum
KB
College of Life Sciences and Biotechnology, Korea University, Seoul, Korea.
Kim
Bong-Woo
BW
Choo
Hyo-Jung
HJ
Kwon
Young-Chan
YC
Ahn
Byung-Yoon
BY
Choi
Jong-Soon
JS
Lee
Jae-Seon
JS
Ko
Young-Gyu
YG
D017667:Adipocytes / Q000737:chemistry* / Q000378:metabolism; D050156:Adipogenesis; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D015536:Down-Regulation; D015180:Electrophoresis, Gel, Two-Dimensional; D005786:Gene Expression Regulation; D018960:Hyaluronan Receptors / Q000032:analysis / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D021962:Membrane Microdomains / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D020543:Proteome / Q000032:analysis*; D034622:RNA Interference; D015398:Signal Transduction
C490193:C1qbp protein, mouse; D018960:Hyaluronan Receptors; D007328:Insulin; D024101:Mitochondrial Proteins; D020543:Proteome