Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Caenorhabditis elegans protein, CeMyoD, is related to the vertebrate myogenic regulatory factors MyoD, myogenin, MRF-4 and Myf-5. Like its vertebrate counterparts, CeMyoD accumulates in the nucleus of striated muscle cells prior to the onset of terminal differentiation. CeMyoD also shares functional similarities with the vertebrate myogenic regulatory factors. Viral LTR driven expression of CeMyoD in mouse 10T1/2 cells can convert this cell line into myoblasts as well as efficiently trans-activate mouse muscle-specific promoters. Furthermore, mouse MyoD expression can activate a CeMyoD-beta-galactosidase reporter construct in a 10T1/2 co-transfection assay.
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PMID:Functional conservation of nematode and vertebrate myogenic regulatory factors. 133 34

Using the basic helix-loop-helix domain of the myogenic factor myogenin as a probe, we identified a clone from a sea urchin cDNA library with considerable sequence similarity to the vertebrate myogenic factors. This cDNA, sea urchin myogenic factor 1 (SUM-1), transactivated a muscle creatine kinase-chloramphenicol acetyltransferase reporter gene in 10T1/2 fibroblasts to a level comparable to that of the vertebrate myogenic factors. In addition, bacterially expressed beta-galactosidase-SUM-1 fusion protein interacted directly with the kappa E-2 site in the muscle creatine kinase enhancer core as assayed by electrophoretic mobility shift assays. Stably transfected SUM-1 activated the muscle differentiation program and converted 10T1/2 cells from fibroblasts to myotubes. In sea urchin embryos, SUM-1 RNA was not detected before gastrulation. It accumulated to its highest levels during the prism stage when myoblasts were first detected by myosin immunostaining and then diminished as myocytes differentiated. SUM-1 protein was localized in secondary mesenchyme cells when they could first be identified as muscle cells by myosin immunostaining. These results implicate SUM-1 as a regulatory factor involved in the early decision of a pluripotent secondary mesenchyme cell to convert to a myogenic fate. SUM-1 is an example of an invertebrate myogenic factor that is capable of functioning in mammalian cells.
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PMID:A myogenic factor from sea urchin embryos capable of programming muscle differentiation in mammalian cells. 206 3

The expression of myogenin is suppressed during innervation and has been implicated in determining properties of skeletal muscle which are regulated by electrical activity. We previously reported that transcription driven by 3700 bp of the mouse myogenin upstream sequence (MYG3700) is activated by denervation in transgenic mice (Nucleic Acids Res. 21, 5684-5693, 1993). To extend our investigation of the activity dependence of the myogenin promoter, we have utilized myoblast implantation as a novel approach to in vivo reporter analysis. Myoblasts for hindlimb injections were generated by stable transfection of chloramphenicol acetyltransferase (CAT) reporters into a beta-galactosidase-expressing line of C2 cells. In vitro characterization of stable myoblast clones carrying myogenin-CAT deletion constructs revealed that while the proximal myogenin 5'-flanking sequence confers myotube specificity, high-level expression requires a region upstream (-335 to -1102) which depends on chromosomal integration for its function. For analysis by implantation, incorporation of injected myoblasts into existing myofibers was confirmed by histochemical staining. Using clonal myoblasts harboring nicotinic receptor alpha-subunit (alpha 800) and myosin light chain receptors as positive and negative controls, respectively, for denervation responsiveness, we determined that the nuclei of injected myoblasts are susceptible to regulatory signals imposed by nerve-induced electrical activity of the myofiber into which they incorporate. In in vivo analysis of myogenin upstream sequence by implantation, CAT activities of MYG3700 and MYG1565 reporters in injected limbs increased up to fourfold within 4 days after denervation, whereas the activities of MYG1102 and MYG335 were unchanged. By 10 days after denervation, all myogenin reporters displayed denervation responsiveness. These implantation data suggest an early phase of denervation activation, one that is mediated by control elements residing within -1102 to -1565 of the myogenin upstream sequence. Thus, the combined analyses of stable reporter myoblast lines in vitro and in vivo by implantation provide an efficient means of evaluating regulatory regions for high-level expression and neural modulation of muscle gene transcription.
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PMID:Analysis of neural-responsive myogenin upstream sequences by myoblast implantation. 861 76

Myocardial infarcts heal by scar formation because there are no stem cells in myocardium, and because adult myocytes cannot divide and repopulate the wound. We sought to redirect the heart to form skeletal muscle instead of scar by transferring the myogenic determination gene, MyoD, into cardiac granulation (wound repair) tissue. A replication-defective adenovirus was constructed containing MyoD under transcriptional control of the Rous sarcoma virus long terminal repeat. The virus converted cultured cardiac fibroblasts to skeletal muscle, indicated by expression of myogenin and skeletal myosin heavy chains (MHCs). To determine if MyoD could induce muscle differentiation in vivo, we injected 2 x 10(9) or 10(10) pfu of either the MyoD or a control beta-galactosidase adenovirus into healing rat hearts, injured 1 wk previously by freeze-thaw. After receiving the lower viral dose, cardiac granulation tissue expressed MyoD mRNA and protein, but did not express myogenin or skeletal MHC. When the higher dose of virus was administered, double immunostaining showed that cells in reparative tissue expressed both myogenin and embryonic skeletal MHC. No muscle differentiation occurred after beta-galactosidase transfection. Thus, MyoD gene transfer can induce skeletal muscle differentiation in healing heart lesions. Modifications of this strategy might eventually provide new contractile tissue to repair myocardial infarcts.
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PMID:Muscle differentiation during repair of myocardial necrosis in rats via gene transfer with MyoD. 894 36

Skeletal muscles in the vertebrate body are derived from the somites, epithelial spheres of cells which segment from the paraxial mesoderm in a rostral-caudal developmental gradient on either side of the neural tube. Initially, cells in the somite are multipotent and their fate depends on the environmental influences exerted by neighbouring tissues, notably the axial structures (neural tube and notochord), and the dorsal ectoderm. The ventralizing influence exerted by the notochord and floor plate of the neural tube through the action of sonic hedgehog, results in the differentiation of sclerotome which will give rise to cartilage and bone of the vertebral column and ribs. The dorsal derivatives of the somite, formed from cells in the dermomyotome, are derm and skeletal muscle. The onset of skeletal myogenesis is characterized by expression of myogenic factors, notably myf-5 and MyoD, members of the superfamily of helix-loop-helix transcription factors. Another member of the myogenic factor family, myogenin, is subsequently expressed and leads to muscle cell differentiation with activation of the downstream muscle-specific genes. Dorsalization of the somite and subsequent myogenesis depends on the presence of axial structures and dorsal ectoderm. The Wnt family of signalling molecules are potentially implicated in this process. Muscle progenitor cells present in the medial part of the dermomyotome activate myf-5 first and explant experiments have shown that the axial structures lead to the activation of this myogenic factor and subsequent myogenesis which results in the formation of the dorsal myotome in the central region of the somite. This contributes to the formation of axial muscles. Muscle progenitor cells in the lateral part of the dermomyotome preferentially activate MyoD and this depends on the presence of dorsal ectoderm. These cells will form the ventral aspect of the myotome, and later contribute to body wall muscles, for example. Part of the lateral progenitor population migrates away from the somite to form peripheral body muscles and the muscles of the limb. In this case myogenic factors are not initially expressed and these migratory cells are characterized by the expression of the paired-box gene Pax3. In explant experiments lateral mesoderm retards the induction of MyoD expression by dorsal ectoderm; in vivo this may be important to permit cell migration prior to differentiation. In mice carrying mutations in both MyoD and myf-5 no skeletal muscle forms, whereas myogenesis can take place in the absence of either MyoD or myf-5. Normally, cells in which one gene is activated first, subsequently co-express the other, so that there rapidly cease to be distinct MyoD+ or myf-5+ populations in the embryo. In myf-5-/- mice no myotome forms initially, but MyoD is subsequently activated. This takes place medially, as well as laterally, under the influence of the more mature neural tube and notochord. By targetting the myf-5 gene with an nlacZ reporter gene it has been possible to follow the fate of the early muscle progenitor cell population in which the myf-5 gene has been activated but no myf-5 protein is present. These beta-galactosidase positive cells delaminate from the dermomyotome, but instead of migrating under this epithelium to form the myotome, they migrate aberrantly. Some cells localize dorsally under the epiderm and begin to express the dermal marker, Dermo-1. Other muscle progenitor cells migrate ventrally into the sclerotomal compartment where they express an early sclerotomal marker, scleraxis. Later in the mutant mice, when cells from this compartment have condensed to form the cartilage of the ribs, beta-galactosidase positive cells are detectable within the ribs. These observations indicate that the early myogenic factor myf-5 is necessary to ensure the correct positioning of myogenic progenitor cells within the embryo. (ABSTRACT TRUNCATED)
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PMID:[Early stages of myogenesis as seen through the action of the myf-5 gene]. 918 Nov 27

We examined a panel of cell lines for the expression of the myogenic proteins myoD and myogenin. High level expression of both proteins was seen in rhabdomyosarcoma (RMS). To determine whether promoter elements from these genes could direct RMS cell-specific expression, we generated reporter constructs containing one or two copies of the myoD enhancer coupled to the SV40 promoter. Transient transfection reporter assays confirmed the selective expression of beta-galactosidase (beta-gal) in 8 RMS cell lines. In contrast, very low expression from the myoD enhancer/SV40 promoter was detected in four non-RMS cell lines. To determine whether the hybrid promoter could elicit RMS-specific cytotoxicity, a mammalian expression vector containing the herpes simplex virus thymidine kinase (HSVtk) under control of the hybrid myoD enhancer/SV40 promoter was constructed. After electroporation into several cell lines, selective RMS cell kill was observed after treatment with ganciclovir. These data suggest that in vivo tumor-specific expression of HSVtk from the myoD enhancer/SV40 promoter may provide an alternative to current chemotherapy.
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PMID:Rhabdomyosarcoma-specific expression of the herpes simplex virus thymidine kinase gene confers sensitivity to ganciclovir. 969 70

Myogenin, one of the MyoD family of proteins, is expressed early during somitogenesis and is required for myoblast fusion in vivo. Previous studies in transgenic mice have shown that a 184-bp myogenin promoter fragment is sufficient to correctly drive expression of a beta-galactosidase transgene during embryogenesis. We show here that mutation of one of the DNA motifs present in this region, the MEF3 motif, abolished correct expression of this beta-galactosidase transgene. We have found that the proteins that bind to the MEF3 site are homeoproteins of the Six/sine oculis family. Antibodies directed specifically against Six1 or Six4 proteins reveal that each of these proteins is present in the embryo when myogenin is activated and constitutes a muscle-specific MEF3-binding activity in adult muscle nuclear extracts. Both of these proteins accumulate in the nucleus of C2C12 myogenic cells, and transient transfection experiments confirm that Six1 and Six4 are able to transactivate a reporter gene containing MEF3 sites. Altogether these results establish Six homeoproteins as a family of transcription factors controlling muscle formation through activation of one of its key regulators, myogenin.
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PMID:Expression of myogenin during embryogenesis is controlled by Six/sine oculis homeoproteins through a conserved MEF3 binding site. 982 81

A lacZ transgene, expressed by the myogenin promoter, was introduced into the mouse hypoxanthine phosphoribosyltransferase (Hprt) locus by gene targeting in embryonic stem cells. Embryos between E10.5-E18.5 days were analyzed for expression of the transgene after staining for beta-galactosidase activity. Transgene expression was restricted to the skeletal muscle lineages reflecting a similar temporal and spatial pattern previously demonstrated for the endogenous myogenin gene. Additionally, a second transgene, MC1tk, showed expression in 87% of the clones when targeted to Hprt. This strategy, called targeted transgenesis, provides control for analyzing promoter sequences and for comparing various transgenes expressed by the same promoter.
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PMID:Temporal, spatial and tissue-specific expression of a myogenin-lacZ transgene targeted to the Hprt locus in mice. 1040 78

Six4 is a member of the Six family genes, homologues of Drosophila melanogaster sine oculis. The gene is thought to be involved in neurogenesis, myogenesis, and development of other organs, based on its specific expression in certain neuronal cells of the developing embryo and in adult skeletal muscles. To elucidate the biological roles of Six4, we generated Six4-deficient mice by replacing the Six homologous region and homeobox by the beta-galactosidase gene. 5-Bromo-4-chloro-3-indolyl-beta-D-galactopyranoside staining of the heterozygous mutant embryos revealed expression of Six4 in cranial and dorsal root ganglia, somites, otic and nasal placodes, branchial arches, Rathke's pouch, apical ectodermal ridges of limb buds, and mesonephros. The expression pattern was similar to that of Six1 except at the early stage of embryonic day 8.5. Six4-deficient mice were born according to the Mendelian rule with normal gross appearance and were fertile. No hearing defects were detected. Six4-deficient embryos showed no morphological abnormalities, and the expression patterns of several molecular markers, e.g., myogenin and NeuroD3 (neurogenin1), were normal. Our results indicate that Six4 is not essential for mouse embryogenesis and suggest that other members of the Six family seem to compensate for the loss of Six4.
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PMID:Six4, a putative myogenin gene regulator, is not essential for mouse embryonal development. 1131 60

Satellite cells (SC) in adult muscle are quiescent in the G0 phase of the cell cycle. In the present study we determined whether SC after denervation upregulate M-cadherin, an adhesion molecule that is upregulated with differentiation and fusion. We also monitored primary cultures of SC from denervated muscle for expression of the transcription factors of the MyoD family to determine whether SC from denervated muscle can be activated in vitro. Hindlimb muscles of rats were denervated under anesthesia, and rats were killed after 2-28 days. The SC of the denervated limbs were pooled and either assessed for M-cadherin mRNA by using real-time RT-PCR or cultured in vitro. The cultures were processed for RT-PCR or immunofluorescence for expression of the transcription factors of the MyoD family. Hindlimb muscles of M-cadherin knockout mice were denervated under anesthesia, mice were killed after 2-28 days, and cells were stained for beta-galactosidase activity by X-gal histochemistry. In vitro, primary SC cultures from rat muscle denervated for 2-28 days expressed transcripts of myf5, MyoD, myogenin, and MRF4 as SC from normal innervated muscle. In vivo, M-cadherin transcription was not upregulated in SC from denervated rat muscle when compared with normal muscle. Moreover, beta-galactosidase activity was not detected in denervated mouse muscle. The finding that SC do not upregulate M-cadherin after denervation supports the notion that they remain in the G(0) phase of the cell cycle in vivo. However, the cells retain the capacity to pass through the proliferative and differentiative program when robustly stimulated to do so in vitro.
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PMID:M-cadherin transcription in satellite cells from normal and denervated muscle. 1476 88


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