Lab of Molecular and Cellular Biology, Wuxi Medical School, Jiangnan University, Wuxi, Jiangsu, China.
Department of Occupational Health, Wuxi Center for Disease Control and Prevention, Wuxi, Jiangsu, China.
Biochem Biophys Res Commun. 2018 Sep 5;503(2):737-743. doi: 10.1016/j.bbrc.2018.06.069. Epub 2018 Jun 21.
Osteoblast uses aerobic glycolysis to meet the metabolic needs in differentiation process. Lactate, the end product of glycolysis, presents in the environment with elevated PTH and osteoblast differentiation. Although previous findings showed that lactate promoted osteoblast differentiation, whether lactate affects PTH-mediated osteoblast differentiation is unclear. To investigate this, pre-osteoblast cell line MC3T3-E1 was treated PTH with or without physiological dose of lactate. Lactate increases ALP positive cell formation, increases ALP activity and expression of differentiation related markers, enriches the CREB transcriptional factor target genes in PTH treated cells. Using inhibitors for MCT-1 reveales that lactate effects are MCT-1 independent. Lactate selectively increases Akt and p38 activation but not Erk1/2 and β-Catenin activation. The inhibitors for Akt and p38 inhibit lactate effects on PTH mediated osteoblast differentiation. Using inhibitors for Gαi signaling of GPR81 further increases Alp mRNA levels in lactate and PTH co-treatment cells. However, with the inhibitors for Gβγ-PLC-PKC signaling, the effect of lactate on PTH mediated osteoblast differentiation is inhibited. Our data demonstrate that lactate activates GPR81-Gβγ-PLC-PKC-Akt signaling to regulate osteoblast differentiation that mediated by PTH treatment.
成骨细胞利用有氧糖酵解来满足分化过程中的代谢需求。乳酸是糖酵解的终产物，在高甲状旁腺素（PTH）和成骨细胞分化的环境中存在。虽然先前的研究结果表明乳酸促进成骨细胞分化，但乳酸是否影响 PTH 介导的成骨细胞分化尚不清楚。为了研究这一点，用或不用生理剂量的乳酸处理前成骨细胞系 MC3T3-E1 和 PTH。乳酸增加碱性磷酸酶（ALP）阳性细胞的形成，增加 ALP 活性和分化相关标志物的表达，丰富 PTH 处理细胞中的 CREB 转录因子靶基因。使用 MCT-1 的抑制剂表明，乳酸的作用是不依赖于 MCT-1 的。乳酸选择性地增加 Akt 和 p38 的激活，但不增加 Erk1/2 和 β-连环蛋白的激活。Akt 和 p38 的抑制剂抑制了乳酸对 PTH 介导的成骨细胞分化的作用。使用 GPR81 的 Gαi 信号抑制剂进一步增加了乳酸和 PTH 共同处理细胞中 Alp mRNA 的水平。然而，用 Gβγ-PLC-PKC 信号的抑制剂，乳酸对 PTH 介导的成骨细胞分化的作用被抑制。我们的数据表明，乳酸激活 GPR81-Gβγ-PLC-PKC-Akt 信号通路来调节成骨细胞分化，这种作用是由 PTH 处理介导的。
