title: Zinc finger protein ZFP36L1 promotes osteoblastic differentiation but represses adipogenic differentiation of mouse multipotent cells.
abstract: Zinc finger protein 36, C3H type-like 1 (ZFP36L1) is a member of the tristetraprolin (TTP) family and its role in the aging-related bone loss is currently unknown. We present evidence that ZFP36L1 expression in rat femurs and bone marrow mesenchymal stem cells (bmMSCs) was down-regulated with aging. ZFP36L1 knockdown decreased osteoblastic differentiation of MC3T3-E1 and C3H10T1/2 cells, and increased adipogenic differentiation of 3T3-L1 and C3H10T1/2 cells, whereas ZFP36L1 overexpression did the opposite. The finding that ZFP36L1 overexpression enhanced osteoblastic and repressed adipogenic differentiation was also corroborated by ex vivo experiments. Troglitazone prevented ZFP36L1 from inhibiting adipogenic differentiation, suggesting the significance of PPARγ2 repression in ZFP36L1's inhibitory effect on adipogenic differentiation. ZFP36L1 overexpression repressed the expression of Pparγ2 mRNA, but not the PPARγ promoter activity. Biotin pull-down and electrophoretic mobility-shift assays suggested that ZFP36L1 might interact with endogenous Pparγ2 mRNA by binding to its 3'UTR. The ZFP36L1-containing ribonucleoprotein complexes of ZFP36L1-overexpressing cells contained less Pparγ2 mRNA than those of control cells. In a luciferase reporter construct, replacement of the SV40 poly(A) fragment by the 3'UTR of Pparγ2 mRNA reduced the expression of luciferase transcripts in ZFP36L1-overexpressing cells. Examination of the kinetic expression of Pparγ2 mRNA after transcriptional blockage showed that ZFP36L1 might enhance the degradation of the transcripts. Together, these data imply that ZFP36L1 overexpression might repress adipogenesis at least by down-regulating PPARγ2 expression through post-transcriptional mechanisms. Thus, our findings support the notion that decrease of ZFP36L1 expression in bmMSCs with aging might contribute to the aging-related bone loss.
authors.affiliation: Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town, Miaoli, Taiwan, Republic of China.
authors.forename: Kuo-Yun
authors.initials: KY
authors.lastname: Tseng
authors.affiliation: Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town, Miaoli, Taiwan, Republic of China.
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Chen
authors.affiliation: Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town, Miaoli, Taiwan, Republic of China.|Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan, Republic of China.
authors.forename: Shankung
authors.initials: S
authors.lastname: Lin
mesh_terms: D017667:Adipocytes / Q000166:cytology*; D000375:Aging / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D051817:Butyrate Response Factor 1 / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D047468:Immunoprecipitation; D051379:Mice; D039902:Multipotent Stem Cells / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology*; D010024:Osteoporosis / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D051817:Butyrate Response Factor 1; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; C488431:Zfp36l1 protein, mouse; C497555:Zfp36l1 protein, rat
keywords: Gerotarget; ZFP36L1; adipogenesis; aging-related bone loss; osteoblastogenesis; osteoporosis