How osteoblast cells are induced is a central question for understanding skeletal formation. Abnormal osteoblast differentiation leads to a broad range of devastating craniofacial diseases. Here we have investigated i...How osteoblast cells are induced is a central question for understanding skeletal formation. Abnormal osteoblast differentiation leads to a broad range of devastating craniofacial diseases. Here we have investigated intramembranous ossification during cranial bone development in mouse models of skeletal genetic diseases that exhibit craniofacial bone defects. The GNAS gene encodes Gαs that transduces GPCR signaling. GNAS activation or loss-of-function mutations in humans cause fibrous dysplasia(FD) or progressive osseous heteroplasia(POH) that shows craniofacial hyperostosis or craniosynostosis, respectively. We find here that, while Hh ligand-dependent Hh signaling is essential for endochondral ossification, it is dispensable for intramembranous ossification, where Gαsregulates Hh signaling in a ligand-independent manner. We further show that Gαscontrols intramembranous ossification by regulating both Hh and Wnt/β-catenin signaling. In addition, Gαsactivation in the developing cranial bone leads to reduced ossification but increased cartilage presence due to reduced cartilage dissolution, not cell fate switch. Small molecule inhibitors of Hh and Wnt signaling can effectively ameliorate cranial bone phenotypes in mice caused by loss or gain of Gnas function mutations, respectively. Our work shows that studies of genetic diseases provide invaluable insights in both pathological bone defects and normal bone development, understanding both leads to better diagnosis and therapeutic treatment of bone diseases.展开更多
Mandibular defects caused by injuries,tumors,and infections are common and can severely affect mandibular function and the patient's appearance.However,mandible reconstruction with a mandibular bionic structure re...Mandibular defects caused by injuries,tumors,and infections are common and can severely affect mandibular function and the patient's appearance.However,mandible reconstruction with a mandibular bionic structure remains challenging.Inspired by the process of intramembranous ossification in mandibular development,a hierarchical vascularized engineered bone consisting of angiogenesis and osteogenesis modules has been produced.Moreover,the hierarchical vascular network and bone structure generated by these hierarchical vascularized engineered bone modules match the particular anatomical structure of the mandible.The ultra-tough polyion complex has been used as the basic scaffold for hierarchical vascularized engineered bone for ensuring better reconstruction of mandible function.According to the results of in vivo experiments,the bone regenerated using hierarchical vascularized engineered bone is similar to the natural mandibular bone in terms of morphology and genomics.The sonic hedgehog signaling pathway is specifically activated in hierarchical vascularized engineered bone,indicating that the new bone in hierarchical vascularized engineered bone underwent a process of intramembranous ossification identical to that of mandible development.Thus,hierarchical vascularized engineered bone has a high potential for clinical application in mandibular defect reconstruction.Moreover,the concept based on developmental processes and bionic structures provides an effective strategy for tissue regeneration.展开更多
γ-Secretase,called“the proteasome of the membrane,”is a membrane-embedded protease complex that cleaves 150+peptide substrates with central roles in biology and medicine,including amyloid precursor protein and the ...γ-Secretase,called“the proteasome of the membrane,”is a membrane-embedded protease complex that cleaves 150+peptide substrates with central roles in biology and medicine,including amyloid precursor protein and the Notch family of cell-surface receptors.Mutations inγ-secretase and amyloid precursor protein lead to early-onset familial Alzheimer’s disease.γ-Secretase has thus served as a critical drug target for treating familial Alzheimer’s disease and the more common late-onset Alzheimer’s disease as well.However,critical gaps remain in understanding the mechanisms of processive proteolysis of substrates,the effects of familial Alzheimer’s disease mutations,and allosteric modulation of substrate cleavage byγ-secretase.In this review,we focus on recent studies of structural dynamic mechanisms ofγ-secretase.Different mechanisms,including the“Fit-Stay-Trim,”“Sliding-Unwinding,”and“Tilting-Unwinding,”have been proposed for substrate proteolysis of amyloid precursor protein byγ-secretase based on all-atom molecular dynamics simulations.While an incorrect registry of the Notch1 substrate was identified in the cryo-electron microscopy structure of Notch1-boundγ-secretase,molecular dynamics simulations on a resolved model of Notch1-boundγ-secretase that was reconstructed using the amyloid precursor protein-boundγ-secretase as a template successfully capturedγ-secretase activation for proper cleavages of both wildtype and mutant Notch,being consistent with biochemical experimental findings.The approach could be potentially applied to decipher the processing mechanisms of various substrates byγ-secretase.In addition,controversy over the effects of familial Alzheimer’s disease mutations,particularly the issue of whether they stabilize or destabilizeγ-secretase-substrate complexes,is discussed.Finally,an outlook is provided for future studies ofγ-secretase,including pathways of substrate binding and product release,effects of modulators on familial Alzheimer’s disease mutations of theγ-secretase-substrate complexes.Comprehensive understanding of the functional mechanisms ofγ-secretase will greatly facilitate the rational design of effective drug molecules for treating familial Alzheimer’s disease and perhaps Alzheimer’s disease in general.展开更多
Osteogenesis and angiogenesis are two closely correlated processes during bone growth, development, remodelling and repair. Vascular endothelial growth factor （VEGF） is an essential mediator during the process of an...Osteogenesis and angiogenesis are two closely correlated processes during bone growth, development, remodelling and repair. Vascular endothelial growth factor （VEGF） is an essential mediator during the process of angiogenesis. Based on an extensive literature search, which was carried out using the PubMed database and the keywords of osteogenesis, VEGF, endochondral ossification and intramembranous ossification, this manuscript reviews the role of VEGF in ossification, with emphasis on its effect in endochondral and intramembranous ossification. Osteogenesis and angiogenesis are closely correlated processes. VEGF acts as an essential mediator durin~ these processes. It not only functions in bone an^io^enesis but also in various aspects of bone develooment.展开更多
Intermuscular bones(IBs)are slender linear bones embedded in muscle,which ossify from tendons through a process of intramembranous ossification,and only exist in basal teleosts.IBs are essential for fish swimming,but ...Intermuscular bones(IBs)are slender linear bones embedded in muscle,which ossify from tendons through a process of intramembranous ossification,and only exist in basal teleosts.IBs are essential for fish swimming,but they present a choking risk during human consumption,especially in children,which can lead to commercial risks that have a negative impact on the aquaculture of these fish.In this review,we discuss the morphogenesis and functions of IBs,including their underlying molecular mechanisms,as well as the advantages and disadvantages of different methods for IB studies and techniques for breeding and generating IB-free fish lines.This review reveals that the many key genes involved in tendon development,osteoblast differentiation,and bone formation,e.g.,scxa,msxC,sost,twist,bmps,and osterix,also play roles in IB development.Thus,this paper provides useful information for the breeding of new fish strains without IBs via genome editing and artificial selection.展开更多
To evaluate the characteristics and synthesis activity of osteoblasts extracted from the calvaria of offspring of rats exposed to maternal hyperthyroidism.Twelve adult Wistar rats were divided into two groups,one cont...To evaluate the characteristics and synthesis activity of osteoblasts extracted from the calvaria of offspring of rats exposed to maternal hyperthyroidism.Twelve adult Wistar rats were divided into two groups,one control and one treated with daily administration of L-thyroxine by an orogastric tube(50μg/animal/day)during pregnancy.Three days after delivery and confirmation of the mothers’hyperthyroidism,the offspring were euthanized for the extraction of osteoblasts from the calvaria.At 7,14,and 21 days,proliferation activity was assessed using MTT assay,while alkaline phosphatase(ALP)activity was assessed by the BCIP/NBT method.At 21 days,the total area of the mineralized matrix stained by von Kossa was evaluated by morphometry.The expression of gene transcripts for Runx2,Bmp2,Fgfr1,collagen type 1(Col1),osteocalcin(Oc),and osteopontin(Op)were evaluated by real-time RT-PCR.Means were compared using the Student’s t-test.FA activity was significantly higher at 14 and 21 days in cultures of osteoblasts extracted from offspring exposed to maternal hyperthyroidism,while MTT conversion was significantly lower at 21 days in this group.Osteoblast cultures of neonates exposed to maternal hyperthyroidism also showed a larger total area of mineralized matrix and greater expression of gene transcripts for Oc and Op.Maternal hyperthyroidism increases the activity of matrix synthesis,alkaline phosphatase activity,and expression of gene transcripts for osteocalcin and osteopontin in the osteoblasts,extracted from the calvaria of the offspring,which may be one of the mechanisms of premature fusion of cranial sutures.展开更多
Biomaterials are widely used as orthopaedic implants and bone graft substitutes.We aimed to develop a rapid osteogenic assessment method using a murine tibial periosteal ossification model to evaluate the bone forma-t...Biomaterials are widely used as orthopaedic implants and bone graft substitutes.We aimed to develop a rapid osteogenic assessment method using a murine tibial periosteal ossification model to evaluate the bone forma-tion/remodelling potential of a biomaterial within 2-4 weeks.A novel hydroxyapatite/aragonite(HAA)biomaterial was implanted into C57BL/6 mice juxtaskeletally between the tibia and tibialis anterior muscle.Rapid intramembranous bone formation was observed at 14 days,with 4-to 8-fold increases in bone thickness and callus volume in comparison with sham-operated animals(p<0.0001),followed by bone remodelling and a new layer of cortical bone formation by 28 days after implantation.The addition of zoledronate,a clinically-utilised bisphosphonate,to HAA,promoted significantly more new bone formation than HAA alone over 28 days(p<0.01).The osteogenic potential of HAA was further confirmed by implanting into a 3.5 mm diameter femoral cancellous bone defect in rats and a 5 mm diameter femoral cortical bone defect in minipigs.To un-derstand the biodegradation and the cellular activity at the cell/biomaterial interfaces,non-decalcified speci-mens were resin embedded and sections subjected to combined scanning electron microscopy(SEM)/electron backscatter diffraction(EBSD)/energy dispersive X-ray spectrometry(EDS)analysis.We conclude that murine tibial periosteal ossification is a novel method for rapid assessment of the interaction of bioactive materials with osteogenic tissues.This study also highlights that combining calcium carbonate with hydroxyapatite enhances biodegradation and osteogenesis.展开更多
Tissue-resident stem cells are essential for development and repair,and in the skeleton,this function is fulfilled by recently identified skeletal stem cells(SSCs).However,recent work has identified that SSCs are not ...Tissue-resident stem cells are essential for development and repair,and in the skeleton,this function is fulfilled by recently identified skeletal stem cells(SSCs).However,recent work has identified that SSCs are not monolithic,with long bones,craniofacial sites,and the spine being formed by distinct stem cells.Recent studies have utilized techniques such as fluorescence-activated cell sorting,lineage tracing,and single-cell sequencing to investigate the involvement of ssCs in bone development,homeostasis,and disease.These investigations have allowed researchers to map the lineage commitment trajectory of ssCs in different parts of the body and at different time points.Furthermore,recent studies have shed light on the characteristics of ssCs in both physiological and pathological conditions.This review focuses on discussing the spatiotemporal distribution of ssCs and enhancing our understanding of the diversity and plasticity of ssCs by summarizing recent discoveries.展开更多
基金supported by the NIH grants R01DE025866 from NIDCRR01AR070877 from NIAMSsupported by the 111 Project, MOE (B14038), China
文摘How osteoblast cells are induced is a central question for understanding skeletal formation. Abnormal osteoblast differentiation leads to a broad range of devastating craniofacial diseases. Here we have investigated intramembranous ossification during cranial bone development in mouse models of skeletal genetic diseases that exhibit craniofacial bone defects. The GNAS gene encodes Gαs that transduces GPCR signaling. GNAS activation or loss-of-function mutations in humans cause fibrous dysplasia(FD) or progressive osseous heteroplasia(POH) that shows craniofacial hyperostosis or craniosynostosis, respectively. We find here that, while Hh ligand-dependent Hh signaling is essential for endochondral ossification, it is dispensable for intramembranous ossification, where Gαsregulates Hh signaling in a ligand-independent manner. We further show that Gαscontrols intramembranous ossification by regulating both Hh and Wnt/β-catenin signaling. In addition, Gαsactivation in the developing cranial bone leads to reduced ossification but increased cartilage presence due to reduced cartilage dissolution, not cell fate switch. Small molecule inhibitors of Hh and Wnt signaling can effectively ameliorate cranial bone phenotypes in mice caused by loss or gain of Gnas function mutations, respectively. Our work shows that studies of genetic diseases provide invaluable insights in both pathological bone defects and normal bone development, understanding both leads to better diagnosis and therapeutic treatment of bone diseases.
基金National Key Research and Development Program of China(2018YFA0703000)National Natural Science Foundation of China(8212200044,52075482,82071085,81873720)+2 种基金Zhejiang Provincial Natural Science Foundation of China(LR21H140001)Key Research and Development Program of Zhejiang,China(2017C01054,2018C03062)Scientific Research Fund of Zhejiang Provincial Education Department(Y202045564)。
文摘Mandibular defects caused by injuries,tumors,and infections are common and can severely affect mandibular function and the patient's appearance.However,mandible reconstruction with a mandibular bionic structure remains challenging.Inspired by the process of intramembranous ossification in mandibular development,a hierarchical vascularized engineered bone consisting of angiogenesis and osteogenesis modules has been produced.Moreover,the hierarchical vascular network and bone structure generated by these hierarchical vascularized engineered bone modules match the particular anatomical structure of the mandible.The ultra-tough polyion complex has been used as the basic scaffold for hierarchical vascularized engineered bone for ensuring better reconstruction of mandible function.According to the results of in vivo experiments,the bone regenerated using hierarchical vascularized engineered bone is similar to the natural mandibular bone in terms of morphology and genomics.The sonic hedgehog signaling pathway is specifically activated in hierarchical vascularized engineered bone,indicating that the new bone in hierarchical vascularized engineered bone underwent a process of intramembranous ossification identical to that of mandible development.Thus,hierarchical vascularized engineered bone has a high potential for clinical application in mandibular defect reconstruction.Moreover,the concept based on developmental processes and bionic structures provides an effective strategy for tissue regeneration.
基金supported in part by Award 2121063 from National Science Foundation(to YM)AG66986 from the National Institutes of Health(to MSW).
文摘γ-Secretase,called“the proteasome of the membrane,”is a membrane-embedded protease complex that cleaves 150+peptide substrates with central roles in biology and medicine,including amyloid precursor protein and the Notch family of cell-surface receptors.Mutations inγ-secretase and amyloid precursor protein lead to early-onset familial Alzheimer’s disease.γ-Secretase has thus served as a critical drug target for treating familial Alzheimer’s disease and the more common late-onset Alzheimer’s disease as well.However,critical gaps remain in understanding the mechanisms of processive proteolysis of substrates,the effects of familial Alzheimer’s disease mutations,and allosteric modulation of substrate cleavage byγ-secretase.In this review,we focus on recent studies of structural dynamic mechanisms ofγ-secretase.Different mechanisms,including the“Fit-Stay-Trim,”“Sliding-Unwinding,”and“Tilting-Unwinding,”have been proposed for substrate proteolysis of amyloid precursor protein byγ-secretase based on all-atom molecular dynamics simulations.While an incorrect registry of the Notch1 substrate was identified in the cryo-electron microscopy structure of Notch1-boundγ-secretase,molecular dynamics simulations on a resolved model of Notch1-boundγ-secretase that was reconstructed using the amyloid precursor protein-boundγ-secretase as a template successfully capturedγ-secretase activation for proper cleavages of both wildtype and mutant Notch,being consistent with biochemical experimental findings.The approach could be potentially applied to decipher the processing mechanisms of various substrates byγ-secretase.In addition,controversy over the effects of familial Alzheimer’s disease mutations,particularly the issue of whether they stabilize or destabilizeγ-secretase-substrate complexes,is discussed.Finally,an outlook is provided for future studies ofγ-secretase,including pathways of substrate binding and product release,effects of modulators on familial Alzheimer’s disease mutations of theγ-secretase-substrate complexes.Comprehensive understanding of the functional mechanisms ofγ-secretase will greatly facilitate the rational design of effective drug molecules for treating familial Alzheimer’s disease and perhaps Alzheimer’s disease in general.
文摘Osteogenesis and angiogenesis are two closely correlated processes during bone growth, development, remodelling and repair. Vascular endothelial growth factor （VEGF） is an essential mediator during the process of angiogenesis. Based on an extensive literature search, which was carried out using the PubMed database and the keywords of osteogenesis, VEGF, endochondral ossification and intramembranous ossification, this manuscript reviews the role of VEGF in ossification, with emphasis on its effect in endochondral and intramembranous ossification. Osteogenesis and angiogenesis are closely correlated processes. VEGF acts as an essential mediator durin~ these processes. It not only functions in bone an^io^enesis but also in various aspects of bone develooment.
基金This work was supported by the National Natural Science Foundation of China(U1702233 and U1902202)Program of the Chinese Academy of Sciences(XDA24030505 and XDA23080502)Program of Yunnan Provincial Science and Technology Department(202003AD150017 and 2018FY001-007)。
文摘Intermuscular bones(IBs)are slender linear bones embedded in muscle,which ossify from tendons through a process of intramembranous ossification,and only exist in basal teleosts.IBs are essential for fish swimming,but they present a choking risk during human consumption,especially in children,which can lead to commercial risks that have a negative impact on the aquaculture of these fish.In this review,we discuss the morphogenesis and functions of IBs,including their underlying molecular mechanisms,as well as the advantages and disadvantages of different methods for IB studies and techniques for breeding and generating IB-free fish lines.This review reveals that the many key genes involved in tendon development,osteoblast differentiation,and bone formation,e.g.,scxa,msxC,sost,twist,bmps,and osterix,also play roles in IB development.Thus,this paper provides useful information for the breeding of new fish strains without IBs via genome editing and artificial selection.
基金supported by grants from the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)Fundação de Amparo a Pesquisa de Minas Gerais(Fapemig)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior(Capes).
文摘To evaluate the characteristics and synthesis activity of osteoblasts extracted from the calvaria of offspring of rats exposed to maternal hyperthyroidism.Twelve adult Wistar rats were divided into two groups,one control and one treated with daily administration of L-thyroxine by an orogastric tube(50μg/animal/day)during pregnancy.Three days after delivery and confirmation of the mothers’hyperthyroidism,the offspring were euthanized for the extraction of osteoblasts from the calvaria.At 7,14,and 21 days,proliferation activity was assessed using MTT assay,while alkaline phosphatase(ALP)activity was assessed by the BCIP/NBT method.At 21 days,the total area of the mineralized matrix stained by von Kossa was evaluated by morphometry.The expression of gene transcripts for Runx2,Bmp2,Fgfr1,collagen type 1(Col1),osteocalcin(Oc),and osteopontin(Op)were evaluated by real-time RT-PCR.Means were compared using the Student’s t-test.FA activity was significantly higher at 14 and 21 days in cultures of osteoblasts extracted from offspring exposed to maternal hyperthyroidism,while MTT conversion was significantly lower at 21 days in this group.Osteoblast cultures of neonates exposed to maternal hyperthyroidism also showed a larger total area of mineralized matrix and greater expression of gene transcripts for Oc and Op.Maternal hyperthyroidism increases the activity of matrix synthesis,alkaline phosphatase activity,and expression of gene transcripts for osteocalcin and osteopontin in the osteoblasts,extracted from the calvaria of the offspring,which may be one of the mechanisms of premature fusion of cranial sutures.
基金supported by Royal Society International Exchanges Grant 2021(IES\R1\211128)Qu´ebec-Wales Collaboration Grant 2021 and Wales Innovation Network(WIN)Small Grants Fund(SG6-RIR1058-107).
文摘Biomaterials are widely used as orthopaedic implants and bone graft substitutes.We aimed to develop a rapid osteogenic assessment method using a murine tibial periosteal ossification model to evaluate the bone forma-tion/remodelling potential of a biomaterial within 2-4 weeks.A novel hydroxyapatite/aragonite(HAA)biomaterial was implanted into C57BL/6 mice juxtaskeletally between the tibia and tibialis anterior muscle.Rapid intramembranous bone formation was observed at 14 days,with 4-to 8-fold increases in bone thickness and callus volume in comparison with sham-operated animals(p<0.0001),followed by bone remodelling and a new layer of cortical bone formation by 28 days after implantation.The addition of zoledronate,a clinically-utilised bisphosphonate,to HAA,promoted significantly more new bone formation than HAA alone over 28 days(p<0.01).The osteogenic potential of HAA was further confirmed by implanting into a 3.5 mm diameter femoral cancellous bone defect in rats and a 5 mm diameter femoral cortical bone defect in minipigs.To un-derstand the biodegradation and the cellular activity at the cell/biomaterial interfaces,non-decalcified speci-mens were resin embedded and sections subjected to combined scanning electron microscopy(SEM)/electron backscatter diffraction(EBSD)/energy dispersive X-ray spectrometry(EDS)analysis.We conclude that murine tibial periosteal ossification is a novel method for rapid assessment of the interaction of bioactive materials with osteogenic tissues.This study also highlights that combining calcium carbonate with hydroxyapatite enhances biodegradation and osteogenesis.
基金supported in part by National Natural Science Foundation of China(Grant nos.82372362,81972034,92068104 to Ren Xu and 82002262 to Na Li)National Key R&D Program of China(2020YFA0112900 to Ren Xu)+2 种基金Natural Science Foundation of Fujian Province(2022J06003 to Ren Xu)Project of Xiarmen Cell Therapy Research,Xiamen,Fujian,China(3502Z20214001)supported by a Pershing Square MIND Prize award,an Irma T.Hirschl Career Scientist Award,an NIH award RO1AR075585,a Career Award for Medical Scientists from the Burroughs Welcome Foundation,a William Rhodes and Louise Tilzer-Rhodes Center for Glioblastoma research award,and a Weill Comell Medicine Prostate Cancer SPORE Developmental Research Program Award。
文摘Tissue-resident stem cells are essential for development and repair,and in the skeleton,this function is fulfilled by recently identified skeletal stem cells(SSCs).However,recent work has identified that SSCs are not monolithic,with long bones,craniofacial sites,and the spine being formed by distinct stem cells.Recent studies have utilized techniques such as fluorescence-activated cell sorting,lineage tracing,and single-cell sequencing to investigate the involvement of ssCs in bone development,homeostasis,and disease.These investigations have allowed researchers to map the lineage commitment trajectory of ssCs in different parts of the body and at different time points.Furthermore,recent studies have shed light on the characteristics of ssCs in both physiological and pathological conditions.This review focuses on discussing the spatiotemporal distribution of ssCs and enhancing our understanding of the diversity and plasticity of ssCs by summarizing recent discoveries.
