The growth and repair of skeletal muscle after birth depends on satellite cells that are characterized by the expression Pax7. We show Pax3, paralogue Pax7, is also present in both quiescent activated many muscles. Dominant-negative forms Pax3 -7 repress MyoD, but do not interfere with other myogenic determination factor, Myf5, which, together Pax3/7, regulates differentiation these cells. In Pax7 mutants, progressively lost Pax3-expressing -nonexpressing this caused cell death, effects...

Skeletal muscle stem cells are regulated by Pax3/7. During development, Pax3 is required for the maintenance of these in somite and their migration to sites myogenesis; high levels interfere with cell differentiation, both embryo adult. Quantitative fine-tuning critical, microRNAs provide a potential mechanism. We identify microRNA-27b (miR-27b), which directly targets 3'-UTR mRNA, as such regulator. miR-27b expressed differentiating skeletal embryonic myotome activated satellite adult...

Tissue morphogenesis is driven by local cellular deformations that are powered contractile actomyosin networks. How localized forces transmitted across tissues to shape them at a mesoscopic scale still unclear. Analyzing gastrulation in entire avian embryos, we show it the graded contraction of large-scale supracellular ring margin between embryonic and extraembryonic territories. The propagation these enabled fluid-like response epithelial disk, which depends on cell division. A simple...

Pax genes encode evolutionarily conserved transcription factors that play critical roles in development. Pax3 and Pax7 constitute one of the four subfamilies. Despite partially overlapping expression domains, mouse mutations for have very different consequences. To investigate mechanism these contrasting phenotypes, we replaced by using gene targeting mouse. can substitute function dorsal neural tube, crest cell, somite development, but not formation muscles involving long-range migration...

We address the molecular control of myogenesis in progenitor cells derived from hypaxial somite. Null mutations Pax3 , a key regulator skeletal muscle formation, lead to cell death this domain. have developed novel allele encoding Pax3–engrailed fusion protein that acts as transcriptional repressor. Heterozygote mouse embryos an attenuated mutant phenotype, with partial conservation somite and its myogenic derivatives, including some hindlimb muscles. At these sites, expression Myf5 is...

The Escherichia coli lacZ gene has been used as an indicator for the study of cell lineage in vivo. To adapt this marker expression studies, a sequence encoding modified beta-galactosidase and including simian virus 40 large tumor nuclear location signal (nls-beta-Gal) introduced into vectors. In differentiated cells, multipotential embryos, constructs led to enzymatically active protein. Its was examined by its activity or using antibodies electron microscopy. results show that nls-beta-Gal...

Key molecules which regulate the formation of heart have been identified; however, mechanism cardiac morphogenesis remains poorly understood at cellular level. We adopted a genetic approach, permits retrospective clonal analysis myocardial cells in mouse embryo,based on targeting an nlaacZ reporter to α-cardiac actin gene. A rare intragenic recombination event leads clone ofβ-galactosidase-positive cells. Analysis clones different developmental stages demonstrates that and their precursors...

Pax3 is a key transcription factor implicated in development and human disease. To dissect the role of myogenesis establish whether it repressor or activator, we generated loss- gain-of-function alleles by targeting an nLacZ reporter sequence encoding oncogenic fusion protein PAX3-FKHR into locus. Rescue mutant phenotypes suggests that acts as transcriptional activator during embryogenesis. This confirmed Pax mouse. However, mice expressing display developmental defects, including ectopic...

Pax3/7-dependent stem cells play an essential role in skeletal muscle development. We now show that Fgfr4 lies genetically downstream from Pax3 and is a direct target. In chromatin immunoprecipitation (ChIP)-on-chip experiments, binds to sequence 3′ of the gene directs Pax3-dependent expression at sites myogenesis transgenic mouse embryos. The activity this regulatory element also partially dependent on E-boxes, targets myogenic factors, which are expressed as progenitor enter program. Other...

All skeletal muscle progenitor cells in the body derive from dermomyotome, dorsal epithelial domain of developing somites. These multipotent stem express Pax3, and this expression is maintained myogenic lineage where Pax3 plays an important role. Identification targets therefore for understanding mechanisms that underlie onset myogenesis. In a microarray screen Pax3-GFP sorted cells, with analysis on gain loss function genetic backgrounds, we identify Dmrt2, expressed as target. vitro gel...

Limb position along the body is highly consistent within one species but very variable among vertebrates. Despite major advances in our understanding of limb patterning three dimensions, how limbs reproducibly form antero-posterior axis remains largely unknown. Hox genes have long been suspected to control position; however, supporting evidences are mostly correlative and their role this process unclear. Here, we show that determined early development through action genes. Dynamic lineage...

Significance During embryonic development, multipotent stem cells progressively acquire specific cell fates. The somite is an embryological structure that gives rise to different mesodermal types, including skeletal muscle and vascular of blood vessels. We show by genetic manipulation the Notch signaling pathway promotes a cell-fate choice at expense in mouse somite. Pax3 + adjacent somites give myogenic endothelial limbs. Gain-of-function or inhibition affects this prior migration these...

ABSTRACT The myogenic factor Myf5 plays a key role in muscle cell determination, response to signalling cascades that lead the specification of progenitor cells. We have adopted YAC transgenic approach identify regulatory sequences direct complex spatiotemporal expression this gene during myogenesis mouse embryo. Important regions with distinct properties are distributed over 96 kb upstream gene. proximal 23 region directs early branchial arches, epaxial dermomyotome and central part...

A quantitative bioassay for human immunodeficiency viruses has been developed on the basis of ability tat gene to transactivate expression an integrated beta-galactosidase in a HeLa-CD4+ cell line. Infection by single virion HIV-1 or HIV-2 corresponds unique blue syncytium cluster detected after fixation and addition 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (a substrate). The number infected lymphoid cells culture (stimulated peripheral blood lymphocytes lines) can also be...

In mammals, several genetic pathways have been characterized that govern engagement of multipotent embryonic progenitors into the myogenic program through control key regulatory gene Myod. Here we demonstrate involvement Six homeoproteins. We first targeted a Pax3 allele sequence encoding negative form Six4 binds DNA but cannot interact with essential Eya co-factors. The resulting embryos present hypoplasic skeletal muscles and impaired Myod activation in trunk absence Myf5/Mrf4. At axial...

Myf5 is the first myogenic regulatory factor to be expressed in mouse embryo and it determines entry of cells into skeletal muscle programme. A region situated between -58 kb -48 from gene directs transcription at sites where muscles will form. We now show that this consists a number distinct elements specifically target myogenesis somite, limbs hypoglossal cord, also central nervous system. Deletion these sequences context locus shows within are essential, reveals combinatorial complexity...