Intermuscular bones(IBs)are ossified from tendons and only occur in lower teleosts.Positive association between the regulation of scleraxis gene(scx)and tendon development gave us reasons to speculate that the scx gen...Intermuscular bones(IBs)are ossified from tendons and only occur in lower teleosts.Positive association between the regulation of scleraxis gene(scx)and tendon development gave us reasons to speculate that the scx gene may play a potential role in regulating the development of IBs.A phylogenetic analysis conducted for this study revealed potential functional differentiation between two scx orthologues,scxa and scxb.The scxa^(-/-) and scxb^(-/-) zebrafish were generated through CRISPR-Cas9 technology to study the role of scx in the IB and rib development.The results showed a significant reduction of the number of IBs in adult scxa-1^(-/-) zebrafish,with almost 70%reduction(15-25 IBs)compared to the wild type scxa-1^(+/+)zebrafish(76-80 IBs).In the scxa-1^(+/+)adults,IBs were observed in both dorsal and tail segments;however,in scxa-1^(-/-)fish IBs were observed only in the tail segment(none in the dorsal segment).Although scxa-1^(-/-) zebrafish had rib defects,the mutants were viable and fertile as adult fish.The scxb^(-/-) zebrafish had the same number of IBs and same skeletal phenotype as the wild-type fish.This suggests that only scxa has a crucial role in the IB development,and confirms functional differentiation of scx orthologues.To further clarify the molecular mechanism by which scxa affects the IB development,we conducted comparative transcriptome analysis of dorsal tissue samples of scxa-1^(+/+)(with IBs)and scxa-1^(-/-) (without IBs),and further verified the expression of key genes via qPCR.This is the first study to identify a gene that controls the amount of IBs in fish,and it provides a new sight into the effects of scxa on the molecular mechanism of IB development in fish.展开更多
The molecular cascade underlying tendon formation starts when progenitor cells begin to express the Scleraxis(Scx)gene.Scx knockout mice develop some but not all tendons,suggesting that additional factors are necessar...The molecular cascade underlying tendon formation starts when progenitor cells begin to express the Scleraxis(Scx)gene.Scx knockout mice develop some but not all tendons,suggesting that additional factors are necessary for tendon commitment,maintenance,and differentiation.Other transcription factors,such as Mohawk(Mkx)or early growth response(Egr),maintain Scx expression and extracellular matrix formation during fibrillogenesis.The inhibition of wingless and int-related protein signaling is necessary and sufficient to induce the expression of Scx.Once the commitment of tenogenic lineage occurs,transforming growth factor-beta(TGFβ)induces the Scx gene expression,becoming involved in the maintenance of tendon cell fate.From this point of view,we discussed two phases of the tenogenic process during limb development:dependent and independent of mechanical forces.Finally,we highlight the importance of understanding embryonic tendon development to improve therapeutic strategies in regenerative medicines for tendons.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.31872559)National Key Research and Development Program(Grant No.2018YFD0900102)+2 种基金Modern Agriculture Industry Technology System Construction Projects of China titled as-Staple Freshwater Fishes Industry Technology System(Grant No.CARS-46-08)Fundamental Research Funds for the Central Universities(Grant No.2662018PY035)State Key Laboratory of Developmental Biology of Freshwater Fish(2018KF003).
文摘Intermuscular bones(IBs)are ossified from tendons and only occur in lower teleosts.Positive association between the regulation of scleraxis gene(scx)and tendon development gave us reasons to speculate that the scx gene may play a potential role in regulating the development of IBs.A phylogenetic analysis conducted for this study revealed potential functional differentiation between two scx orthologues,scxa and scxb.The scxa^(-/-) and scxb^(-/-) zebrafish were generated through CRISPR-Cas9 technology to study the role of scx in the IB and rib development.The results showed a significant reduction of the number of IBs in adult scxa-1^(-/-) zebrafish,with almost 70%reduction(15-25 IBs)compared to the wild type scxa-1^(+/+)zebrafish(76-80 IBs).In the scxa-1^(+/+)adults,IBs were observed in both dorsal and tail segments;however,in scxa-1^(-/-)fish IBs were observed only in the tail segment(none in the dorsal segment).Although scxa-1^(-/-) zebrafish had rib defects,the mutants were viable and fertile as adult fish.The scxb^(-/-) zebrafish had the same number of IBs and same skeletal phenotype as the wild-type fish.This suggests that only scxa has a crucial role in the IB development,and confirms functional differentiation of scx orthologues.To further clarify the molecular mechanism by which scxa affects the IB development,we conducted comparative transcriptome analysis of dorsal tissue samples of scxa-1^(+/+)(with IBs)and scxa-1^(-/-) (without IBs),and further verified the expression of key genes via qPCR.This is the first study to identify a gene that controls the amount of IBs in fish,and it provides a new sight into the effects of scxa on the molecular mechanism of IB development in fish.
基金supported by the Dirección General de Asuntos del Personal Académico(DGAPA)-Universidad Nacional Autónoma de México[Grant No.IN213314]Consejo Nacional de Ciencia y Tecnología(CONACyT)[Grant No.1887 CONACyTFronteras de la Ciencia]awarded to JC-M.
文摘The molecular cascade underlying tendon formation starts when progenitor cells begin to express the Scleraxis(Scx)gene.Scx knockout mice develop some but not all tendons,suggesting that additional factors are necessary for tendon commitment,maintenance,and differentiation.Other transcription factors,such as Mohawk(Mkx)or early growth response(Egr),maintain Scx expression and extracellular matrix formation during fibrillogenesis.The inhibition of wingless and int-related protein signaling is necessary and sufficient to induce the expression of Scx.Once the commitment of tenogenic lineage occurs,transforming growth factor-beta(TGFβ)induces the Scx gene expression,becoming involved in the maintenance of tendon cell fate.From this point of view,we discussed two phases of the tenogenic process during limb development:dependent and independent of mechanical forces.Finally,we highlight the importance of understanding embryonic tendon development to improve therapeutic strategies in regenerative medicines for tendons.
