Indian hedgehog （Ihh） is an essential signal that regulates endochondral bone development. We have previously shown that Wnt7b promotes osteoblast differentiation during mouse embryogenesis, and that its expression ...Indian hedgehog （Ihh） is an essential signal that regulates endochondral bone development. We have previously shown that Wnt7b promotes osteoblast differentiation during mouse embryogenesis, and that its expression in the perichondrium is dependent on Ihh signaling. To test the hypothesis that Wnt7b may mediate some aspects of Ihh function during endochondral bone development, we activated Wnt7b expression from the R26-Wnt7b allele with Col2-Cre in the Ihh-/- mouse. Artificial expression of Wnt7b rescued vascularization of the hypertrophic cartilage in the Ihh-/- mouse, but failed to restore orthotopic osteoblast differentiation in the perichondrium. Similarly, Wnt7b did not recover Ihh-dependent perichondral bone formation in the Ihh-/-; Gli3-/- embryo. Interestingly, Wnt7b induced bone formation at the diaphyseal region of long bones in the absence of Ihh, possibly due to increased vascularization in the area. Thus, Ihh-dependent expression of Wnt7b in the perichondrium may contribute to vascularization of the hypertrophic cartilage during endochondral bone development.展开更多
Vascular smooth muscle cells have attracted considerable interest as a model for a flexible program of gene expression.This cell type arises throughout the embryo body plan via poorly understood signaling cascades tha...Vascular smooth muscle cells have attracted considerable interest as a model for a flexible program of gene expression.This cell type arises throughout the embryo body plan via poorly understood signaling cascades that direct the expression of transcription factors and microRNAs which,in turn,orchestrate the activation of contractile genes collectively defining this cell lineage.The discovery of myocardin and its close association with serum response factor has represented a major break-through for the molecular understanding of vascular smooth muscle cell differentiation.Retinoids have been shown to improve the outcome of vessel wall remodeling following injury and have provided further insights into the molecular circuitry that defines the vascular smooth muscle cell phenotype.This review summarizes the progress to date in each of these areas of vascular smooth muscle cell biology.展开更多
People have grafted plants since antiquity for propagation,to increase yields,and to improve stress tolerance.This cutting and joining of tissues activates an incredible regenerative ability as different plants fuse a...People have grafted plants since antiquity for propagation,to increase yields,and to improve stress tolerance.This cutting and joining of tissues activates an incredible regenerative ability as different plants fuse and grow as one.For over a hundred years,people have studied the scientific basis for how plants graft.Today,new techniques and a deepening knowledge of the molecular basis for graft formation have allowed a range of previously ungraftable combinations to emerge.Here,we review recent developments in our understanding of graft formation,including the attachment and vascular formation steps.We analyze why plants graft and how biotic and abiotic factors influence successful grafting.We also discuss the ability and inability of plants to graft,and how grafting has transformed both horticulture and fundamental plant science.As our knowledge about plant grafting improves,new combinations and techniques will emerge to allow an expanded use of grafting for horticultural applications and to address fundamental research questions.展开更多
基金supported by NIH grants R01 DK065789 and R01 AR060456 to FL
文摘Indian hedgehog （Ihh） is an essential signal that regulates endochondral bone development. We have previously shown that Wnt7b promotes osteoblast differentiation during mouse embryogenesis, and that its expression in the perichondrium is dependent on Ihh signaling. To test the hypothesis that Wnt7b may mediate some aspects of Ihh function during endochondral bone development, we activated Wnt7b expression from the R26-Wnt7b allele with Col2-Cre in the Ihh-/- mouse. Artificial expression of Wnt7b rescued vascularization of the hypertrophic cartilage in the Ihh-/- mouse, but failed to restore orthotopic osteoblast differentiation in the perichondrium. Similarly, Wnt7b did not recover Ihh-dependent perichondral bone formation in the Ihh-/-; Gli3-/- embryo. Interestingly, Wnt7b induced bone formation at the diaphyseal region of long bones in the absence of Ihh, possibly due to increased vascularization in the area. Thus, Ihh-dependent expression of Wnt7b in the perichondrium may contribute to vascularization of the hypertrophic cartilage during endochondral bone development.
文摘Vascular smooth muscle cells have attracted considerable interest as a model for a flexible program of gene expression.This cell type arises throughout the embryo body plan via poorly understood signaling cascades that direct the expression of transcription factors and microRNAs which,in turn,orchestrate the activation of contractile genes collectively defining this cell lineage.The discovery of myocardin and its close association with serum response factor has represented a major break-through for the molecular understanding of vascular smooth muscle cell differentiation.Retinoids have been shown to improve the outcome of vessel wall remodeling following injury and have provided further insights into the molecular circuitry that defines the vascular smooth muscle cell phenotype.This review summarizes the progress to date in each of these areas of vascular smooth muscle cell biology.
基金supported by a European Research Council starting grant(GRASP-805094)supported by an MSCA Postdoctoral Fellowship(UMOCELF-101069157).
文摘People have grafted plants since antiquity for propagation,to increase yields,and to improve stress tolerance.This cutting and joining of tissues activates an incredible regenerative ability as different plants fuse and grow as one.For over a hundred years,people have studied the scientific basis for how plants graft.Today,new techniques and a deepening knowledge of the molecular basis for graft formation have allowed a range of previously ungraftable combinations to emerge.Here,we review recent developments in our understanding of graft formation,including the attachment and vascular formation steps.We analyze why plants graft and how biotic and abiotic factors influence successful grafting.We also discuss the ability and inability of plants to graft,and how grafting has transformed both horticulture and fundamental plant science.As our knowledge about plant grafting improves,new combinations and techniques will emerge to allow an expanded use of grafting for horticultural applications and to address fundamental research questions.
