Inhibition of preadipocyte differentiation and adipogenesis by zinc-α2-glycoprotein treatment in 3T3-L1 cells.
OBJECTIVE
Zinc-α2-glycoprotein (ZAG) is associated with the loss of adipose tissue in cancer cachexia, and has recently been proposed to be a candidate factor in the regulation of bodyweight. The aim of the study was to investigate the effects of ZAG on the proliferation and differentiation of 3T3-L1 preadipocytes.


METHODS
3-(4,5-Dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide (MTT) spectrophotometry, Oil Red O staining, intracellular triglyceride assays, real-time quantitative reverse transcription polymerase chain reaction and transient transfection methods were used to explore the action of ZAG.


RESULTS
Ectopic ZAG expression significantly stimulates 3T3-L1 cells proliferation in a dose- and time-dependent manner. The maximum influence of ZAG on proliferation was 1.43-fold higher than what was observed in control cells. This effect was observed 144 h after transfection with 0.16 μg of murine ZAG (mZAG) plasmid (P < 0.001). The intracellular lipids content in mZAG over-expressing cells were decreased as much as 37% when compared with the control cells after differentiation (P < 0.05, P < 0.01). The messenger ribonucleic acid levels of peroxisome proliferators-activated receptor-γ (PPARγ), CCAAT enhancer-binding protein-α (C/EBPα) and the critical lipogenic gene, fatty acid synthase (FAS), are also downregulated by up to 50% in fully differentiated ZAG-treated adipocytes. ZAG suppresses FAS messenger ribonucleic acid expression by reducing FAS promoter activity.


CONCLUSIONS
Zinc-α2-glycoprotein stimulates the proliferation and inhibits the differentiation of 3T3-L1 murine preadipocytes. The inhibitory action of ZAG on cell differentiation might be a result of the attenuation of the expression of PPARγ, C/EBPα and the lipogenic-specific enzyme FAS by reducing FAS promoter activity.
Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China.
Hui-Juan
HJ
Zhu
Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China ; Department of Rheumatology Renji Hospital, School of Medicine Shanghai Jiao Tong University Shanghai China.
Hui-Hua
HH
Ding
Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China.
Jie-Ying
JY
Deng
Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China.
Hui
H
Pan
Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China.
Lin-Jie
LJ
Wang
Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China.
Nai-Shi
NS
Li
Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China.
Xiang-Qing
XQ
Wang
Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China.
Yi-Fan
YF
Shi
Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China.
Feng-Ying
FY
Gong
3T3‐L1 preadipocytes; Differentiation; Zinc‐α2‐glycoprotein