Fluoride Regulate Osteoblastic Transforming Growth Factor-β1 Signaling by Mediating Recycling of the Type I Receptor ALK5

Abstract

This study aimed to preliminary investigate the role of activin receptor-like kinase (ALK) 5 as one of TGF-βR1 subtypes in bone turnover and osteoblastic differentiation induced by fluoride. We analyzed bone mineral density and the expression of genes related with transforming growth factor-β1(TGF-β1) signaling and bone turnover in rats treated by different concentrations of fluoride with or without SB431542 in vivo. Moreover, MTT assay, alkaline phosphatase staining, RT-PCR, immunocytochemical analysis and western blot analysis were used to detect the influence on bone marrow stem cells (BMSC) after stimulating by varying concentration of fluoride with or without SB431542 in vitro. The in vivo study showed SB431542 treatment affected bone density and gene expression of rats, which indicated TGF-β1 and ALK5 might take part in fluoride-induced bone turnover and bone formation. The in vitro study showed low concentration of fluoride improved BMSC cells viability, alkaline phosphatase activity, and osteocalcin protein expression which were inhibited by high concentration of fluoride. The gene expression of Runx2 and ALK5 in cells increased after low concentration fluoride treatment which was also inhibited by high concentration of fluoride. Fluoride treatment inhibited gene and protein expression of Samd3 (except 1 mgF-/L). Compared with fluoride treatment alone, cells differentiation was inhibited with SB431542 treatment. Moreover, the expression of Runx2, ALK5 and Smad3 were influenced by SB431542 treatment. In conclusion, this preliminary study indicated that fluoride regulated osteoblastic TGFβ1 signaling in bone turnover and cells differentiation via ALK5.

Aberrant activation of latent transforming growth factor-β initiates the onset of temporomandibular joint osteoarthritis

“… 56 Moreover, the TGF-I ameliorated the abnormal role of high levels of active TGF-β1 in bone formation and directly attenuated Smad2/3 phosphorylation. 57 , 58 In our study, injection of the TGF-I significantly decreased the number of p-Smad2/3-positive cells in the condylar cartilage and subchondral bone in the TMD model. The significant increase in Osterix-positive cells in the subchondral bone of the TGF-I group may trigger the bone formation process and lead to increased bone mass in subchondral bone.…”

Effect of Fluoride Doping in Laponite Nanoplatelets on Osteogenic Differentiation of Human Dental Follicle Stem Cells (hDFSCs)

“…The mineralization state, formation of inorganic calcium is studied using alizarin red staining wherein the inorganic calcium deposition acts as a marker of mineralization and osteogenesis 23,24 . hDFSCs cultured in NCM in the presence of higher concentration of both silicate platelets (NS − F or NS + F) such as 50 µg.mL −1 and 100 µg.mL −1 , show mineral deposition (calcium staining by alizarin red).…”

“…Moreover, these NS may provide sites for mineralization. It is reported that fluoride down-regulates TGF-β1 signaling 37 , and also up regulates bone mineralization by enhancing osteoblast differentiation 24 , and stimulating alkaline phosphatase (ALP) activity and OPN, a matrix protein found in mineralized tissues and plays a pivotal role in modulating osteoclastic activities. These in vitro studies have demonstrated that NS have an anabolic effect on enhancement of hDFSCs differentiation to osteoblasts.…”

Identifying Pleiotropic SNPs Associated With Femoral Neck and Heel Bone Mineral Density

“…Another putative causal SNP, rs4776341, overlaps with an active enhancer-type chromatin in osteoblasts, is an intronic variant located in the sterile alpha motif domain containing 3 (SMAD3) gene, which is part of the important TGF-β1 signaling pathway for osteoblast and osteoclast differentiation via the TGF-β1 signaling pathway ( Yang et al, 2017 ). Interestingly, the SNP rs4776341 is associated with eBMD and FNK-BMD by the cFDR method.…”