Parathyroid hormone(PTH) regulates bone remodeling by activating PTH type 1 receptor(PTH1R) in osteoblasts/osteocytes. Insulinlike growth factor type 1(IGF-1) stimulates mesenchymal stem cell differentiation to osteob...Parathyroid hormone(PTH) regulates bone remodeling by activating PTH type 1 receptor(PTH1R) in osteoblasts/osteocytes. Insulinlike growth factor type 1(IGF-1) stimulates mesenchymal stem cell differentiation to osteoblasts. However, little is known about the signaling mechanisms that regulates the osteoblast-to-osteocyte transition. Here we report that PTH and IGF-I synergistically enhance osteoblast-to-osteocyte differentiation. We identified that a specific tyrosine residue, Y494, on the cytoplasmic domain of PTH1R can be phosphorylated by insulin-like growth factor type I receptor(IGF1R) in vitro. Phosphorylated PTH1R localized to the barbed ends of actin filaments and increased actin polymerization during morphological change of osteoblasts into osteocytes.Disruption of the phosphorylation site reduced actin polymerization and dendrite length. Mouse models with conditional ablation of PTH1R in osteoblasts demonstrated a reduction in the number of osteoctyes and dendrites per osteocyte, with complete overlap of PTH1R with phosphorylated-PTH1R positioning in osteocyte dendrites in wild-type mice. Thus, our findings reveal a novel signaling mechanism that enhances osteoblast-to-osteocyte transition by direct phosphorylation of PTH1R by IGF1R.展开更多
目的探讨间歇性甲状旁腺激素相关蛋白(parathyroid hormone related protein,PTHrP)刺激在成牙骨质细胞中对细胞凋亡和成牙骨质矿化相关蛋白和细胞因子表达的影响。方法应用成牙骨质细胞OCCM-30,使用PTHrP(1-36)、甲状旁腺激素I型受体(p...目的探讨间歇性甲状旁腺激素相关蛋白(parathyroid hormone related protein,PTHrP)刺激在成牙骨质细胞中对细胞凋亡和成牙骨质矿化相关蛋白和细胞因子表达的影响。方法应用成牙骨质细胞OCCM-30,使用PTHrP(1-36)、甲状旁腺激素I型受体(parathyroid hormone type I receptor,PTH1R)阻断剂PTHrP(7-34)对细胞进行间歇性刺激,间歇性给药模式包含3个周期,48 h/周期,分为对照组、PTHrP(1-36)组及PTH1R阻断剂组。采用流式细胞术检测细胞凋亡;采用茜素红染色观察矿化功能;采用real-time PCR和Western blotting法检测细胞内成牙骨质矿化相关蛋白-骨桥素(osteopontin,OPN)、I型胶原蛋白(collagen-1,COL-1)及成牙骨质相关细胞因子I型胰岛素样生长因子-1(insulin like growth factor-1,IGF-1)的基因表达及蛋白质表达。结果间断性PTHrP抑制成牙骨质细胞凋亡,PTH1R阻断剂促进成牙骨质细胞凋亡(P<0.05);PTHrP间断性刺激能够显著增加成牙骨质细胞内OPN、COL-1、IGF-1基因及蛋白表达(P<0.05);PTH1R阻断剂抑制成牙骨质细胞内OPN、COL-1、IGF-1基因及蛋白表达(P<0.05)。结论间断性PTHrP可通过与成牙骨质细胞上PTH1R相互作用抑制细胞凋亡,促进成牙骨质细胞矿化以及相关蛋白和细胞因子的表达。展开更多
Cartilage development is controlled by the highly synergistic proliferation and differentiation of growth plate chondrocytes,in which the Indian hedgehog(IHH)and parathyroid hormone-related protein-parathyroid hormone...Cartilage development is controlled by the highly synergistic proliferation and differentiation of growth plate chondrocytes,in which the Indian hedgehog(IHH)and parathyroid hormone-related protein-parathyroid hormone-1 receptor(PTHrP-PTH1R)feedback loop is crucial.The inositol-requiring enzyme 1a/X-box-binding protein-1 spliced(IRE1α/XBP1s)branch of the unfolded protein response(UPR)is essential for normal cartilage development.However,the precise role of ER stress effector IRE1α,encoded by endoplasmic reticulum to nucleus signaling 1(ERN1),in skeletal development remains unknown.Herein,we reported that loss of IRE1α accelerates chondrocyte hypertrophy and promotes endochondral bone growth.ERN1 acts as a negative regulator of chondrocyte proliferation and differentiation in postnatal growth plates.Its deficiency interrupted PTHrP/PTH1R and IHH homeostasis leading to impaired chondrocyte hypertrophy and differentiation.XBP1s,produced by p-IRE1α-mediated splicing,binds and up-regulates PTH1R and IHH,which coordinate cartilage development.Meanwhile,ER stress cannot be activated normally in ERN1-deficient chondrocytes.In conclusion,ERN1 deficiency accelerates chondrocyte hypertrophy and cartilage mineralization by impairing the homeostasis of the IHH and PTHrP/PTH1R feedback loop and ER stress.ERN1 may have a potential role as a new target for cartilage growth and maturation.展开更多
基金provided by K01-AR060433 (T.Q.)K08-AR064833 (J.C)R01-AR063943 (X.C)
文摘Parathyroid hormone(PTH) regulates bone remodeling by activating PTH type 1 receptor(PTH1R) in osteoblasts/osteocytes. Insulinlike growth factor type 1(IGF-1) stimulates mesenchymal stem cell differentiation to osteoblasts. However, little is known about the signaling mechanisms that regulates the osteoblast-to-osteocyte transition. Here we report that PTH and IGF-I synergistically enhance osteoblast-to-osteocyte differentiation. We identified that a specific tyrosine residue, Y494, on the cytoplasmic domain of PTH1R can be phosphorylated by insulin-like growth factor type I receptor(IGF1R) in vitro. Phosphorylated PTH1R localized to the barbed ends of actin filaments and increased actin polymerization during morphological change of osteoblasts into osteocytes.Disruption of the phosphorylation site reduced actin polymerization and dendrite length. Mouse models with conditional ablation of PTH1R in osteoblasts demonstrated a reduction in the number of osteoctyes and dendrites per osteocyte, with complete overlap of PTH1R with phosphorylated-PTH1R positioning in osteocyte dendrites in wild-type mice. Thus, our findings reveal a novel signaling mechanism that enhances osteoblast-to-osteocyte transition by direct phosphorylation of PTH1R by IGF1R.
文摘目的探讨间歇性甲状旁腺激素相关蛋白(parathyroid hormone related protein,PTHrP)刺激在成牙骨质细胞中对细胞凋亡和成牙骨质矿化相关蛋白和细胞因子表达的影响。方法应用成牙骨质细胞OCCM-30,使用PTHrP(1-36)、甲状旁腺激素I型受体(parathyroid hormone type I receptor,PTH1R)阻断剂PTHrP(7-34)对细胞进行间歇性刺激,间歇性给药模式包含3个周期,48 h/周期,分为对照组、PTHrP(1-36)组及PTH1R阻断剂组。采用流式细胞术检测细胞凋亡;采用茜素红染色观察矿化功能;采用real-time PCR和Western blotting法检测细胞内成牙骨质矿化相关蛋白-骨桥素(osteopontin,OPN)、I型胶原蛋白(collagen-1,COL-1)及成牙骨质相关细胞因子I型胰岛素样生长因子-1(insulin like growth factor-1,IGF-1)的基因表达及蛋白质表达。结果间断性PTHrP抑制成牙骨质细胞凋亡,PTH1R阻断剂促进成牙骨质细胞凋亡(P<0.05);PTHrP间断性刺激能够显著增加成牙骨质细胞内OPN、COL-1、IGF-1基因及蛋白表达(P<0.05);PTH1R阻断剂抑制成牙骨质细胞内OPN、COL-1、IGF-1基因及蛋白表达(P<0.05)。结论间断性PTHrP可通过与成牙骨质细胞上PTH1R相互作用抑制细胞凋亡,促进成牙骨质细胞矿化以及相关蛋白和细胞因子的表达。
基金supported by the National Natural Science Foundation of China(No.81672209,81871769,82272550)the Chongqing Science and Technology Bureau(China)(No.cstc2021jcyj-bshX0214).
文摘Cartilage development is controlled by the highly synergistic proliferation and differentiation of growth plate chondrocytes,in which the Indian hedgehog(IHH)and parathyroid hormone-related protein-parathyroid hormone-1 receptor(PTHrP-PTH1R)feedback loop is crucial.The inositol-requiring enzyme 1a/X-box-binding protein-1 spliced(IRE1α/XBP1s)branch of the unfolded protein response(UPR)is essential for normal cartilage development.However,the precise role of ER stress effector IRE1α,encoded by endoplasmic reticulum to nucleus signaling 1(ERN1),in skeletal development remains unknown.Herein,we reported that loss of IRE1α accelerates chondrocyte hypertrophy and promotes endochondral bone growth.ERN1 acts as a negative regulator of chondrocyte proliferation and differentiation in postnatal growth plates.Its deficiency interrupted PTHrP/PTH1R and IHH homeostasis leading to impaired chondrocyte hypertrophy and differentiation.XBP1s,produced by p-IRE1α-mediated splicing,binds and up-regulates PTH1R and IHH,which coordinate cartilage development.Meanwhile,ER stress cannot be activated normally in ERN1-deficient chondrocytes.In conclusion,ERN1 deficiency accelerates chondrocyte hypertrophy and cartilage mineralization by impairing the homeostasis of the IHH and PTHrP/PTH1R feedback loop and ER stress.ERN1 may have a potential role as a new target for cartilage growth and maturation.
