Background: Vitamin A and its metabolite,retinoic acid(RA),are important regulators of cell differentiation and organ morphogenesis.Its impact on beef cattle muscle growth remains undefined.Method: Angus steer calves ...Background: Vitamin A and its metabolite,retinoic acid(RA),are important regulators of cell differentiation and organ morphogenesis.Its impact on beef cattle muscle growth remains undefined.Method: Angus steer calves were administrated with 0(control) or 150,000 IU vitamin A(retinyl palmitate in glycerol,i.m.) per calf at birth and 1 month of age.At 2 months of age,a biopsy of the Biceps femoris muscle was obtained to analyze the immediate effects of vitamin A injection on myogenic capacity of muscle cells.The resulting steers were harvested at 14 months of age.Results: Vitamin A administration increased cattle growth at 2 months.At 2 months of age,Vitamin A increased PAX7 positive satellite cells and the expression of myogenic marker genes including PAX7,MYF5,MYOD and MYOG.Muscle derived mononuclear cells were further isolated and induced myogenesis in vitro.More myotubes and a higher degree of myogenesis was observed in vitamin A groups.Consistently,vitamin A increased Latissimus dorsi(LD) muscle fiber size at harvest.In addition,vitamin A increased the ratio of oxidative type I and type IIA fibers and reduced the glycolic type IIX fibers.Furthermore,we found that RA,a key bioactive metabolite of vitamin A,activated PPARGC1 A promoter,which explains the upregulated expression of PPARGC1 A in skeletal muscle.Conclusion: Vitamin A administration to neonatal calves enhanced postnatal muscle growth by promoting myogenesis and increasing satellite cell density,accompanied with a shift to oxidative muscle fibers.展开更多
In vertebrates, the skeletal muscles of the body and their associated stem cells originate from muscle progenitor cells,during development. The specification of the muscles of the trunk, head and limbs, relies on the ...In vertebrates, the skeletal muscles of the body and their associated stem cells originate from muscle progenitor cells,during development. The specification of the muscles of the trunk, head and limbs, relies on the activity of distinctgenetic hierarchies. The major regulators of trunk and limb muscle specification are the paired-homeobox transcriptionfactors PAX3 and PAX7. Distinct gene regulatory networks drive the formation of the different muscles of thehead. Despite the redeployment of diverse upstream regulators of muscle progenitor differentiation, the commitmenttowards the myogenic fate requires the expression of the early myogenic regulatory factors MYF5, MRF4, MYOD andthe late differentiation marker MYOG. The expression of these genes is activated by muscle progenitors throughoutdevelopment, in several waves of myogenic differentiation, constituting the embryonic, fetal and postnatal phases ofmuscle growth. In order to achieve myogenic cell commitment while maintaining an undifferentiated pool of muscleprogenitors, several signaling pathways regulate the switch between proliferation and differentiation of myoblasts.The identification of the gene regulatory networks operating during myogenesis is crucial for the development ofin vitro protocols to differentiate pluripotent stem cells into myoblasts required for regenerative medicine.展开更多
基金supported by Agriculture and Food Research Initiative Competitive Grants No.2015–67015-23219 and 2016–68006-24634 from the USDA National Institute of Food and Agriculture
文摘Background: Vitamin A and its metabolite,retinoic acid(RA),are important regulators of cell differentiation and organ morphogenesis.Its impact on beef cattle muscle growth remains undefined.Method: Angus steer calves were administrated with 0(control) or 150,000 IU vitamin A(retinyl palmitate in glycerol,i.m.) per calf at birth and 1 month of age.At 2 months of age,a biopsy of the Biceps femoris muscle was obtained to analyze the immediate effects of vitamin A injection on myogenic capacity of muscle cells.The resulting steers were harvested at 14 months of age.Results: Vitamin A administration increased cattle growth at 2 months.At 2 months of age,Vitamin A increased PAX7 positive satellite cells and the expression of myogenic marker genes including PAX7,MYF5,MYOD and MYOG.Muscle derived mononuclear cells were further isolated and induced myogenesis in vitro.More myotubes and a higher degree of myogenesis was observed in vitamin A groups.Consistently,vitamin A increased Latissimus dorsi(LD) muscle fiber size at harvest.In addition,vitamin A increased the ratio of oxidative type I and type IIA fibers and reduced the glycolic type IIX fibers.Furthermore,we found that RA,a key bioactive metabolite of vitamin A,activated PPARGC1 A promoter,which explains the upregulated expression of PPARGC1 A in skeletal muscle.Conclusion: Vitamin A administration to neonatal calves enhanced postnatal muscle growth by promoting myogenesis and increasing satellite cell density,accompanied with a shift to oxidative muscle fibers.
基金FR laboratory is supported by funding from Association Française contre les Myopathies(AFM)via TRANSLAMUSCLE(PROJECT 19507 and 22946)Agence Nationale pour la Recherche(ANR)grant Epimuscle(ANR 11 BSV201702)RHU CARMMA(ANR-15-RHUS-0003).
文摘In vertebrates, the skeletal muscles of the body and their associated stem cells originate from muscle progenitor cells,during development. The specification of the muscles of the trunk, head and limbs, relies on the activity of distinctgenetic hierarchies. The major regulators of trunk and limb muscle specification are the paired-homeobox transcriptionfactors PAX3 and PAX7. Distinct gene regulatory networks drive the formation of the different muscles of thehead. Despite the redeployment of diverse upstream regulators of muscle progenitor differentiation, the commitmenttowards the myogenic fate requires the expression of the early myogenic regulatory factors MYF5, MRF4, MYOD andthe late differentiation marker MYOG. The expression of these genes is activated by muscle progenitors throughoutdevelopment, in several waves of myogenic differentiation, constituting the embryonic, fetal and postnatal phases ofmuscle growth. In order to achieve myogenic cell commitment while maintaining an undifferentiated pool of muscleprogenitors, several signaling pathways regulate the switch between proliferation and differentiation of myoblasts.The identification of the gene regulatory networks operating during myogenesis is crucial for the development ofin vitro protocols to differentiate pluripotent stem cells into myoblasts required for regenerative medicine.
