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)

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 basic helix-loop-helix (bHLH) transcription factors, Hand1 and Hand2 (refs 1,2), also called eHand/Hxt/Thing1 and dHand/Hed/Thing2 (refs 3,4), respectively, are expressed in the heart and certain neural-crest derivatives during embryogenesis. In addition, Hand1 is expressed in extraembryonic membranes, whereas Hand2 is expressed in the deciduum. Previous studies have demonstrated that Hand2 is required for formation of the right ventricle of the heart and the aortic arch arteries. We have generated a germline mutation in the mouse Hand1 gene by replacing the first coding exon with a beta-galactosidase reporter gene. Embryos homozygous for the Hand1 null allele died between embryonic days 8.5 and 9.5 and exhibited yolk sac abnormalities due to a deficiency in extraembryonic mesoderm. Heart development was also perturbed and did not progress beyond the cardiac-looping stage. Our results demonstrate important roles for Hand1 in extraembryonic mesodermal and heart development.
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PMID:Heart and extra-embryonic mesodermal defects in mouse embryos lacking the bHLH transcription factor Hand1. 950 May 50

Neuronal PAS domain protein 2 (NPAS2) is a basic helix-loop-helix (bHLH) PAS domain transcription factor expressed in multiple regions of the vertebrate brain. Targeted insertion of a beta-galactosidase reporter gene (lacZ) resulted in the production of an NPAS2-lacZ fusion protein and an altered form of NPAS2 lacking the bHLH domain. The neuroanatomical expression pattern of NPAS2-lacZ was temporally and spatially coincident with formation of the mature frontal association/limbic forebrain pathway. NPAS2-deficient mice were subjected to a series of behavioral tests and were found to exhibit deficits in the long-term memory arm of the cued and contextual fear task. Thus, NPAS2 may serve a dedicated regulatory role in the acquisition of specific types of memory.
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PMID:Impaired cued and contextual memory in NPAS2-deficient mice. 1086 74

The neuronal stem cell leukemia (NSCL) basic helix-loop-helix factors are neural cell-specific transcription factors. We have disrupted the NSCL-1 gene by homologous recombination and replaced the coding region with a beta-galactosidase reporter cassette to study the role of NSCL-1 in neuronal development and to follow the fate of NSCL-1 mutant cells. NSCL-1 mutant mice are viable and fertile on various genetic backgrounds and do not show any obvious signs of neurological malfunction. No differences in the distribution of NSCL-1 mutant or heterozygous neuronal cells were observed in the diencephalon, hippocampus, neocortex, and cerebellum at different stages of development. Likewise, no defects were found in the laminar organization of the cortex, and the distinct neuronal subpopulation appeared normal during development of the neocortex. Analysis of sensory neurons which strongly express NSCL-1 revealed that the spatiotemporal expression of neuronal differentiation factors, such as NeuroD and SCG-10, was not altered in developing distal and proximal cranial ganglia of mutant mice. In the cerebellum expression of NSCL-1 was confined to the proliferative and premigratory zone of the external granular layer and the internal granular layer. Interestingly, unlike cerebella of Math1(-/-) or NeuroD2(-/-) mice, NSCL-1-deficient mice have no obvious developmental defect, and neurons of the cerebellum appeared fully differentiated. Despite similar expression patterns of NSCL-1 and NSCL-2 in various areas of the diencephalon, including the arcuate nucleus and paraventricular nucleus, NSCL-1(-/-) mice are fertile and show no adult onset of obesity like NSCL-2 mutant mice. Double-mutant NSCL-1(-/-)-NSCL-2(-/-) mice do not show any additional obvious malformations of the central nervous system, although both genes are expressed in a largely overlapping pattern. Our results argue against a simple functional redundancy within the NSCL gene family.
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PMID:The neuronal basic helix-loop-helix transcription factor NSCL-1 is dispensable for normal neuronal development. 1178 56

Exposure to the environmental contaminant dioxin, elicits a variety of responses, which includes tumor promotion, embryotoxicity/teratogenesis, and carcinogenesis in both animals and humans. Many of the effects of dioxin are mediated by the aryl hydrocarbon receptor (AHR), a ligand-activated bHLH (basic helix-loop-helix)/PAS transcription factor. We initiated this study to determine whether dioxin's tumor-promoting activities may lie in its ability to alter proliferation, differentiation, and/or senescence using normal human epidermal keratinocytes (HEKs). Here, we report that dioxin appears to accelerate differentiation as measured by flow cytometry and by increased expression of the differentiation markers involucrin and filaggrin. In addition, dioxin appears to increase proliferation as indicated by an increase in NADH/NADPH production and changes in cell cycle. Finally, dioxin decreases SA (senescence associated) beta-galactosidase staining, an indicator of senescence, in the differentiating keratinocytes. These changes were accompanied by decreases in the expression levels of key cell cycle regulatory proteins p53, p16INK4a, and p14ARF. Our findings support the idea that dioxin may exert its tumor-promoting actions, in part, by downregulating the expression levels of key tumor suppressor proteins, which may impair the cell's ability to maintain its appropriate cellular status.
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PMID:Alteration of keratinocyte differentiation and senescence by the tumor promoter dioxin. 1455 Jul 47

The stem cell leukemia (SCL) gene, also known as TAL-1, encodes a basic helix-loop-helix protein that is essential for the formation of all hematopoietic lineages, including primitive erythropoiesis. Appropriate transcriptional regulation is essential for the biological functions of SCL, and we have previously identified five distinct enhancers which target different subdomains of the normal SCL expression pattern. However, it is not known whether these SCL enhancers also regulate neighboring genes within the SCL locus, and the erythroid expression of SCL remains unexplained. Here, we have quantitated transcripts from SCL and neighboring genes in multiple hematopoietic cell types. Our results show striking coexpression of SCL and its immediate downstream neighbor, MAP17, suggesting that they share regulatory elements. A systematic survey of histone H3 and H4 acetylation throughout the SCL locus in different hematopoietic cell types identified several peaks of histone acetylation between SIL and MAP17, all of which corresponded to previously characterized SCL enhancers or to the MAP17 promoter. Downstream of MAP17 (and 40 kb downstream of SCL exon 1a), an additional peak of acetylation was identified in hematopoietic cells and was found to correlate with expression of SCL but not other neighboring genes. This +40 region is conserved in human-dog-mouse-rat sequence comparisons, functions as an erythroid cell-restricted enhancer in vitro, and directs beta-galactosidase expression to primitive, but not definitive, erythroblasts in transgenic mice. The SCL +40 enhancer provides a powerful tool for studying the molecular and cellular biology of the primitive erythroid lineage.
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PMID:Transcriptional regulation of the SCL locus: identification of an enhancer that targets the primitive erythroid lineage in vivo. 1592 36

With the use of in vivo recombination theory, the screening time of yeast one-hybrid system was decreased in the present study. A basic helix-loop-helix (bHLH) protein PsGBF was successfully obtained from a glutathione (GSH)-induced pea cDNA library using the G-box cis-element of the PsCHS1 promoter as a bait. Electrophoretic mobility shift assay (EMSA) and beta-galactosidase assay results suggested that PsGBF possesses both G-box-specific binding and transcription-activating activities. The specific interaction of PsGBF with G-box was further confirmed by in vivo transient expression assays in tobacco. The current study examined the combination effect of G-box with Box I elements in the interaction with PsGBF or OsMYC. The results indicated that PsGBF bound with the G-box, but not the Box I element. Moreover, this combination effect of G-box and Box I only associated with PsGBF but not with other bHLH-type proteins such as OsMYC.
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PMID:Identification of a bHLH-type G-box binding factor and its regulation activity with G-box and Box I elements of the PsCHS1 promoter. 1692 2

Increasing evidence suggests that long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs) have roles during biotic and abiotic stress, though their exact contributions remain unclear. To explore their biological functions in response to chilling in bell pepper, we examined their accumulation profiles by deep sequencing and identified 380 lncRNAs, 36 circRNAs, 18 miRNAs, and 4128 differentially expressed mRNAs in the chilled versus the non-chilled fruit. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed differentially expressed genes and putative ncRNA targets, including transcription factors of multiple classes, such as myeloblastosis (MYB), basic helix-loop-helix (bHLH), and ethylene response factor (ERF) transcription factors (TFs), enzymes involved in bio-oxidation and oxidative phosphorylation (serine/threonine-protein kinase, polyphenol oxidase, catalase, peroxidase, lipoxygenase, and ATPase), and cell wall metabolism-related enzymes (beta-galactosidase, pectate lyase, pectinesterase, and polygalacturonase). On the basis of the accumulation profiles, a network of putatively interacting RNAs associated with bell pepper chilling was developed, which pointed to ncRNAs that could provide the foundation for further developing a more refined understanding of the molecular response to chilling injury.
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PMID:Analysis of the Coding and Non-Coding RNA Transcriptomes in Response to Bell Pepper Chilling. 2998 49