Osteoporosis(OP)is a common and fracture-prone skeletal disease characterized by deteriorated trabecular microstructure and pathologically involving various forms of regulated bone cell death.However,the exact role,ce...Osteoporosis(OP)is a common and fracture-prone skeletal disease characterized by deteriorated trabecular microstructure and pathologically involving various forms of regulated bone cell death.However,the exact role,cellular nature and regulatory mechanisms of ferroptosis in OP are not fully understood.Here,we reported that OP femurs from ovariectomized(Ovx)mice exhibited pronounced iron deposition,ferroptosis,and transcriptional suppression of a key anti-ferroptotic factor GPX4(glutathione peroxidase 4).GPX4 suppression was accompanied by hypermethylation of the Gpx4 promoter and an increase in DNA methyltransferases DNMT1/3a/3b and was transcriptionally promoted by repressive KLF5 and the transcriptional corepressors NCoR and SnoN.Conversely,DNMT inhibition with SGI-1027 reversed promoter hypermethylation,GPX4 suppression and ferroptotic osteoporosis.In cultured primary bone cells,ferric ammonium citrate(FAC)mimicking iron loading similarly induced GPX4 suppression and ferroptosis in osteoblasts but not in osteoclasts,which were rescued by siRNA-mediated individual knockdown of DNMT 1/3a/3b.Intriguingly,SGI-1027 alleviated the ferroptotic changes caused by FAC,but not by a GPX4 inactivator RSL3.More importantly,we generated a strain of osteoblast-specific Gpx4 haplo-deficient mice Gpx4^(Ob+/−)that developed spontaneous and more severe ferroptotic OP alterations after Ovx operation,and showed that GPX4 inactivation by RSL3 or semi-knockout in osteoblasts largely abolished the anti-ferroptotic and osteoprotective effects of SGI-1027.Taken together,our data suggest that GPX4 epigenetic suppression caused by DNMT aberration and the resulting osteoblastic ferroptosis contribute significantly to OP pathogenesis,and that the strategies preserving GPX4 by DNMT intervention are potentially effective to treat OP and related bone disorders.展开更多
Metal wear particles generated by the movement of joint prostheses inevitably lead to aseptic osteolytic damage and ultimately prosthesis loosening,which are aggravated by various types of regulated cell death of bone...Metal wear particles generated by the movement of joint prostheses inevitably lead to aseptic osteolytic damage and ultimately prosthesis loosening,which are aggravated by various types of regulated cell death of bone.Nevertheless,the exact cellular nature and regulatory network underlying osteoferroptosis are poorly understood.Here,we report that titanium particles(TP)induced severe peri-implant osteolysis and ferroptotic changes with concomitant transcriptional repression of a key anti-ferroptosis factor,GPX4,in a mouse model of calvarial osteolysis.GPX4 repression was accompanied by an increase in DNA methyltransferases(DNMTs)1/3a/3b and hypermethylation of the Gpx4 promoter,which were partly mediated by the transcriptional regulator/co-repressor KLF5 and NCoR.Conversely,treatment with SGI-1027,a DNMT-specific inhibitor,resulted in marked reversal of Gpx4 promoter hypermethylation and GPX4 repression,as well as improvement in ferroptotic osteolysis to a similar extent as with a ferroptosis inhibitor,liproxstatin-1.This suggests that epigenetic GPX4 repression and ferroptosis caused by the increase of DNMT1/3a/3b have a causal influence on TP-induced osteolysis.In cultured primary osteoblasts and osteoclasts,GPX4 repression and ferroptotic changes were observed primarily in osteoblasts that were alleviated by SGI-1027 in a GPX4 inactivation-sensitive manner.Furthermore,we developed a mouse strain with Gpx4 haplodeficiency in osteoblasts(Gpx4^(0b+/-))thatexhibited worsened ferroptotic osteolysis in control and TP-treated calvaria and largely abolished the anti-ferroptosis and osteoprotective effects of SGl-1027.Taken together,our results demonstrate that DNMT1/3a/3b elevation,resulting GPX4 repression,and osteoblastic ferroptosis form a critical epigenetic pathway that significantly contributes to TP-induced osteolysis,and that targeting DNMT aberration and the associated osteoferroptosis could be a potential strategy to prevent or slow down prosthesis-related osteolytic complications.展开更多
基金supported by the National Key Research and Development Program of China (2023YFB3810200,2023YFB3810204,2022YFF0710801)the National Natural Science Foundation of China (82470749,82370899,82272502,82072423)。
文摘Osteoporosis(OP)is a common and fracture-prone skeletal disease characterized by deteriorated trabecular microstructure and pathologically involving various forms of regulated bone cell death.However,the exact role,cellular nature and regulatory mechanisms of ferroptosis in OP are not fully understood.Here,we reported that OP femurs from ovariectomized(Ovx)mice exhibited pronounced iron deposition,ferroptosis,and transcriptional suppression of a key anti-ferroptotic factor GPX4(glutathione peroxidase 4).GPX4 suppression was accompanied by hypermethylation of the Gpx4 promoter and an increase in DNA methyltransferases DNMT1/3a/3b and was transcriptionally promoted by repressive KLF5 and the transcriptional corepressors NCoR and SnoN.Conversely,DNMT inhibition with SGI-1027 reversed promoter hypermethylation,GPX4 suppression and ferroptotic osteoporosis.In cultured primary bone cells,ferric ammonium citrate(FAC)mimicking iron loading similarly induced GPX4 suppression and ferroptosis in osteoblasts but not in osteoclasts,which were rescued by siRNA-mediated individual knockdown of DNMT 1/3a/3b.Intriguingly,SGI-1027 alleviated the ferroptotic changes caused by FAC,but not by a GPX4 inactivator RSL3.More importantly,we generated a strain of osteoblast-specific Gpx4 haplo-deficient mice Gpx4^(Ob+/−)that developed spontaneous and more severe ferroptotic OP alterations after Ovx operation,and showed that GPX4 inactivation by RSL3 or semi-knockout in osteoblasts largely abolished the anti-ferroptotic and osteoprotective effects of SGI-1027.Taken together,our data suggest that GPX4 epigenetic suppression caused by DNMT aberration and the resulting osteoblastic ferroptosis contribute significantly to OP pathogenesis,and that the strategies preserving GPX4 by DNMT intervention are potentially effective to treat OP and related bone disorders.
基金supported by the National Major Research Plan of National Natural and Science Foundation of China(NSFC)(92368201)National Key Research and Development Project(2021YFA1201404)+4 种基金Major Project of NSFC(81991514)NSFC General Program(81970577)Jiangsu Provincial Key Medical Center Foundation,Jiangsu Province Medical Innovation Center of Orthopedic Surgery(CXZX-202214)Jiangsu Provincial Medical Youth Talent Foundation,Jiangsu Provincial Medical Outstanding Talent Foundation,Jiangsu Provincial Key Medical Talent Foundationthe Fundamental Research Funds for the Central Universities(14380493 and 14380494)。
文摘Metal wear particles generated by the movement of joint prostheses inevitably lead to aseptic osteolytic damage and ultimately prosthesis loosening,which are aggravated by various types of regulated cell death of bone.Nevertheless,the exact cellular nature and regulatory network underlying osteoferroptosis are poorly understood.Here,we report that titanium particles(TP)induced severe peri-implant osteolysis and ferroptotic changes with concomitant transcriptional repression of a key anti-ferroptosis factor,GPX4,in a mouse model of calvarial osteolysis.GPX4 repression was accompanied by an increase in DNA methyltransferases(DNMTs)1/3a/3b and hypermethylation of the Gpx4 promoter,which were partly mediated by the transcriptional regulator/co-repressor KLF5 and NCoR.Conversely,treatment with SGI-1027,a DNMT-specific inhibitor,resulted in marked reversal of Gpx4 promoter hypermethylation and GPX4 repression,as well as improvement in ferroptotic osteolysis to a similar extent as with a ferroptosis inhibitor,liproxstatin-1.This suggests that epigenetic GPX4 repression and ferroptosis caused by the increase of DNMT1/3a/3b have a causal influence on TP-induced osteolysis.In cultured primary osteoblasts and osteoclasts,GPX4 repression and ferroptotic changes were observed primarily in osteoblasts that were alleviated by SGI-1027 in a GPX4 inactivation-sensitive manner.Furthermore,we developed a mouse strain with Gpx4 haplodeficiency in osteoblasts(Gpx4^(0b+/-))thatexhibited worsened ferroptotic osteolysis in control and TP-treated calvaria and largely abolished the anti-ferroptosis and osteoprotective effects of SGl-1027.Taken together,our results demonstrate that DNMT1/3a/3b elevation,resulting GPX4 repression,and osteoblastic ferroptosis form a critical epigenetic pathway that significantly contributes to TP-induced osteolysis,and that targeting DNMT aberration and the associated osteoferroptosis could be a potential strategy to prevent or slow down prosthesis-related osteolytic complications.
