title: Fluoride affects calcium homeostasis and osteogenic transcription factor expressions through L-type calcium channels in osteoblast cell line.
abstract: Osteoblast L-type voltage-dependent calcium channels (VDCC) play important roles in maintaining intracellular homeostasis and influencing multiple cellular processes. In particular, they contribute to the activities and functions of osteoblasts (OBs). In order to study how L-type VDCC modulate calcium ion (Ca(2+)) homeostasis and the expression of osteogenic transcription factors in OBs exposed to fluoride, MC3T3-E1 cells were exposed to a gradient of concentrations of fluoride (0, 2.0, 5.0, 10.0 mg/L) in combination with 10 μM nifedipine, a specific inhibitor of VDCC, for 48 h. We examined messenger RNA (mRNA) and protein levels of Cav1.2, the main subunit of VDCC, and c-fos, c-jun, runt-related transcription factor 2 (Runx2), osterix (OSX), and intracellular free Ca(2+) ([Ca(2+)]i) concentrations in MC3T3-E1 cells. Our results showed that [Ca(2+)]i levels increased in a dose-dependent manner with increase in concentration of fluoride. Meantime, results indicated that lower concentrations of fluoride (less than 5 mg/L, especially 2 mg/L) can lead to high expression of Cav1.2 and enhance osteogenic function, while high concentration of fluoride (10 mg/L) can induce decreased Cav1.2 and osteogenic transcriptional factors in MC3T3E1 cells exposed to fluoride. However, the levels of [Ca(2+)]i, Cav1.2, c-fos, c-jun, Runx2, and OSX induced by fluoride were significantly altered and even reversed in the presence of nifedipine. These results demonstrate that L-type calcium channels play a crucial role in Ca(2+) homeostasis and they affect the expression of osteogenic transcription factors in fluoride-treated osteoblasts.
authors.affiliation: Department of Rehabilitation Medicine of the Second Hospital Norman Bethune, JiLin University, Changchun, 130041, People's Republic of China.
authors.forename: Xiao-Qin
authors.initials: XQ
authors.lastname: Duan
authors.forename: Zhi-Tao
authors.initials: ZT
authors.lastname: Zhao
authors.forename: Xiu-Yun
authors.initials: XY
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Huan
authors.initials: H
authors.lastname: Wang
authors.forename: Da-Wei
authors.initials: DW
authors.lastname: Liu
authors.forename: Guang-Sheng
authors.initials: GS
authors.lastname: Li
authors.forename: Ling
authors.initials: L
authors.lastname: Jing
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D002460:Cell Line; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism; D005459:Fluorides / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006706:Homeostasis / Q000187:drug effects; D051379:Mice; D009543:Nifedipine / Q000494:pharmacology; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D020746:Calcium Channels, L-Type; D050659:Core Binding Factor Alpha 1 Subunit; C419385:L-type calcium channel alpha(1C); D016760:Proto-Oncogene Proteins c-fos; D000076182:Sp7 Transcription Factor; C479466:Sp7 protein, mouse; D014157:Transcription Factors; D009543:Nifedipine; D005459:Fluorides; D002118:Calcium