title: L-carnitine affects osteoblast differentiation in NIH3T3 fibroblasts by the IGF-1/PI3K/Akt signalling pathway.
abstract: Fibroblasts in soft tissues are one of the progenitors of ectopic calcification. Our previous experiment found that the serum concentrations of small metabolite L-carnitine (LC) decreased in an ectopic calcification animal model, indicating LC is a potential calcification or mineralization inhibitor. In this study, we investigated the effect of LC on NIH3T3 fibroblast osteoblast differentiation, and explored its possible molecular mechanisms. Two concentrations of LC (10 μM and 100 μM) were added in Pi-induced NIH3T3 fibroblasts, cell proliferation was compared by MTT assays, osteoblast differentiation was evaluated by ALP activity, mineralized nodules formation, calcium deposition, and expressions of the osteogenic marker genes. Our results indicated that 10 μM LC increased the proliferation of NIH3T3 cells, but 100 μM LC slightly inhibited cell proliferation. 100 μM LC inhibits NIH3T3 differentiation as evidenced by decreases in ALP activity, mineralized nodule formation, calcium deposition, and down-regulation of the osteogenic marker genes ALP, Runx2 and OCN, meanwhile 10 μM of LC exerts an opposite effect that promotes NIH3T3 osteogenesis. Mechanistically, 100 μM LC significantly inhibits IGF-1/PI3K/Akt signalling, while 10 μM LC slightly activates this pathway. Our study suggests that a decease in LC level might contribute to the development of ectopic calcification in fibroblasts by affecting IGF-1/PI3K/Akt, and addition of LC may benefit patients with ectopic calcification.
authors: Key Laboratory for Rare Disease Research of Shandong Province, Key Laboratory for Biotech Drugs of the Ministry of Health,  2 School of Medicine and Life Sciences, University of  Jinan-Shandong Academy of Medical Science, Ji'nan, Shandong, China.
authors: Pinglan
authors: P
authors: Ge
authors: Yazhou
authors: Y
authors: Cui
authors: Fang
authors: F
authors: Liu
authors: Jing
authors: J
authors: Luan
authors: Xiaoyan
authors: X
authors: Zhou
authors: Jinxiang
authors: J
authors: Han
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002114:Calcinosis / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002331:Carnitine / Q000494:pharmacology* / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects* / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D051379:Mice; D041681:NIH 3T3 Cells; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: C519530:insulin-like growth factor-1, mouse; D007334:Insulin-Like Growth Factor I; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D002331:Carnitine; D002118:Calcium