title: Enhanced mitochondrial biogenesis contributes to Wnt induced osteoblastic differentiation of C3H10T1/2 cells.
abstract: Mitochondria play a key role in cell physiology including cell differentiation and proliferation. We investigated the changes of mitochondrial biogenesis during Wnt-induced osteoblastic differentiation of murine mesenchymal C3H10T1/2 cells. Scanning electron microscopy demonstrated that activation of Wnt signaling by Wnt-3A conditioned medicum (CM) resulted in significant increase in the number of mitochondria in C3H10T1/2 cells. In addition, the induction of alkaline phosphatase (ALP) activities by Wnt-3A CM was accompanied by significant increase in mitochondrial mass (p<0.05), mitochondrial membrane potential (p<0.05), intracellular reactive oxygen species production (p<0.05), resting oxygen consumption rate (p<0.05), cellular ATP content (p< or =0.05) and mtDNA copy number (p<0.05) compared to the cells with control CM (L292-CM) treatment. Moreover, co-treatment with Dkk-1 or WIF-1, both of which are Wnt inhibitors, abrogated the Wnt-3A-induced ALP activities as well as mitochondrial biogenesis markers. Upregulation of mitochondrial biogenesis by overexpression of mitochondrial transcription factor A (Tfam) significantly enhanced Wnt-induced osteogenesis as measured by ALP activities. In contrast, inhibition of mitochondrial biogenesis by treatment with Zidovudine (AZT) resulted in significant inhibition of ALP activities. Finally, ALP activities in human osteosarcoma cell line devoid of mitochondrial DNA (rho(0) cells) was significantly suppressed both in basal and Wnt-3A stimulated state compared to those from mitochondria-intact cells (rho+ cells). As a mechanism for Wnt-mediated mitochondrial biogenesis, we found that Wnt increased the expression of PGC-1alpha, a critical molecules in mitochondrial biogenesis, through Erk and p38 MAPK pathway independent of beta-catenin signaling. We also found that increased mitochondrial biogenesis is in turn positively regulating TOPflash reporter activity as well as beta-catenin levels. To summarize, mitochodrial biogenesis is upregulated by Wnt signaling and this upregulation contributes to the osteoblastic differentiation of mouse mesenchymal C3H10T1/2 cells.
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jee Hyun
authors.initials: JH
authors.lastname: An
authors.forename: Jae-Yeon
authors.initials: JY
authors.lastname: Yang
authors.forename: Byung Yong
authors.initials: BY
authors.lastname: Ahn
authors.forename: Sun Wook
authors.initials: SW
authors.lastname: Cho
authors.forename: Ju Yeon
authors.initials: JY
authors.lastname: Jung
authors.forename: Hwa Young
authors.initials: HY
authors.lastname: Cho
authors.forename: Young Min
authors.initials: YM
authors.lastname: Cho
authors.forename: Sang Wan
authors.initials: SW
authors.lastname: Kim
authors.forename: Kyong Soo
authors.initials: KS
authors.lastname: Park
authors.forename: Seong Yeon
authors.initials: SY
authors.lastname: Kim
authors.forename: Hong Kyu
authors.initials: HK
authors.lastname: Lee
authors.forename: Chan Soo
authors.initials: CS
authors.lastname: Shin
mesh_terms: D050156:Adipogenesis / Q000187:drug effects; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D017077:Culture Media, Conditioned / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D010012:Osteogenesis / Q000187:drug effects; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000187:drug effects; D051153:Wnt Proteins / Q000494:pharmacology*; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: D017077:Culture Media, Conditioned; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; C555510:WNT3A protein, human; D051153:Wnt Proteins; D060508:Wnt3 Protein; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; D051176:beta Catenin; D020928:Mitogen-Activated Protein Kinases