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 Spec1 and Spec2 genes of Strongylocentrotus purpuratus are closely associated with the differentiation of aboral ectoderm. To examine cis-regulatory elements involved in the spatial expression of the Spec genes, we fused the Escherichia coli lacZ gene containing a nuclear targeting signal to 5'flanking DNA plus 5' untranslated leader sequences from Spec1, Spec2a, and Spec2c. All three genes contain 700 bp of highly conserved DNA in their upstream regions, but in Spec1 and Spec2c large insertions interrupt the conserved regions. The Spec-lacZ reporter gene plasmids were microinjected into eggs of S. purpuratus, Lytechinus variegatus, and L. pictus, and beta-galactosidase activity was determined in situ by X-gal staining. The Spec2a-lacZ fusion gene, which contained 1516 bp of 5' flanking DNA and 18 bp of 5' untranslated leader sequence, was preferentially expressed in aboral ectoderm cells in all three species. The Spec1-lacZ fusion gene was expressed in a strikingly different fashion--preferentially in primary and secondary mesenchyme cells, occasionally in aboral ectoderm cells, and less often in oral ectoderm and endoderm cells. The staining pattern was the same in either homologous or heterologous embryos. The Spec2c-lacZ fusion gene, like Spec2a-lacZ, was preferentially expressed in aboral ectoderm, but staining of other cell types was frequently observed. To further delineate sequences required for correct spatial expression, we deleted 800 bp of 5' flanking DNA from the Spec2a-lacZ fusion gene, resulting in a delta Spec2a-lacZ fusion gene that contained only the conserved DNA region. This gene fusion showed preferential expression in aboral ectoderm cells. However, the cell type specificity was not as great as with the parental Spec2a-lacZ plasmid. These experiments implied that the conserved DNA region, associated with all Spec genes examined, was insufficient for complete aboral ectoderm specificity, and suggested that a spatial repressor element existed between -1516 and -697 bp in the 5' flanking DNA of Spec2a.
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PMID:Regulatory elements from the related spec genes of Strongylocentrotus purpuratus yield different spatial patterns with a lacZ reporter gene. 170 36

A collagen molecule in the sea urchin embryo was characterized by analysis of a 2.7-kb cDNA clone. This clone, Spcoll, was obtained by screening a gastrula stage Strongylocentrotus purpuratus cDNA library with a 237-bp genomic clone encoding a collagen-like sequence previously isolated by Venkatesan et al. (1986). DNA sequence analysis of the cDNA clone demonstrated the nonfibrillar nature of the encoded molecule--13 interruptions of the Gly-X-Y repeat motif were found in the 85-kDa open reading frame. The mRNA of approximately 9 kb accumulated specifically in mesenchyme cells of the embryo through development to the pluteus larva. Polyclonal antibodies generated against a Spcoll-beta-galactosidase fusion protein were utilized to identify and localize the native Spcoll. This collagen molecule of approximately 210 kDa was deposited into the blastocoel by the primary mesenchyme cells. When primary mesenchyme cells were cultured in vitro, Spcoll was secreted into the media and accumulated at sites of cell-substrate interaction. Addition of anti-Spcoll antibodies to primary mesenchyme cell cultures selectively inhibited spiculogenesis, whereas other antibodies had no inhibitory effect. Since collagen is not a component of the organic matrix of spicules (Benson et al., 1986), these results suggest that the autonomous production of Spcoll by differentiating mesenchyme cells in turn influences the point in differentiation at which these cell initiate biomineralization.
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PMID:Primary mesenchyme cells of the sea urchin embryo require an autonomously produced, nonfibrillar collagen for spiculogenesis. 193 64

To understand how the maternally determined animal-vegetal polarity of the sea urchin embryo is established, we have begun to examine the regulatory apparatus of the gene encoding the Strongylocentrotus purpuratus hatching enzyme (SpHE). Previous studies have shown that the pattern of SpHE mRNA accumulation reflects the animal-vegetal developmental axis in that transcription is strongly upregulated during early cleavage in more animal blastomeres, but not in those around the maternally specified vegetal pole of the 16-cell embryo [Reynolds et al., Development 114, 769-786 (1992)]. Tests of SpHE promoter function in vivo using chloramphenicol acetyltransferase and beta-galactosidase enzymatic reporters define a regulatory region within several hundred nucleotides of the transcription initiation site. This region is sufficient to mediate both strong expression in the early blastula and spatially correct transcription. However, neither this region nor longer upstream sequences are sufficient to reproduce the transcriptional downregulation after very early blastula stage that is observed for endogenous genes. Biochemical assays of protein-DNA interactions within the regulatory region identify at least nine sites binding at least six different factors. These cis elements include Otx (an orthodenticle homologue), CCAAT, ets-related, and three unidentified motifs. Deletions and/or replacements of these cis-elements, alone and in combination, indicate that no single factor is essential for SpHE promoter activity, but instead that various combinations of subsets of these elements are capable of eliciting levels of transcription similar to those of the unaltered regulatory region. This density of regulatory elements is consistent with the intense transcription of endogenous SpHE genes during cleavage.
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PMID:Characterization of the SpHE promoter that is spatially regulated along the animal-vegetal axis of the sea urchin embryo. 755 96

Complementary DNA clones for exogastrula-inducing peptides (EGIPs) of the sea urchin Anthocidaris crassispina, which are related to epidermal growth factor (EGF), were obtained from a cDNA library of late gastrula embryos using, as probe, the partial cDNA for one of the EGIP (EGIP-D) obtained by the reverse-transcription PCR method. The longest cDNA was composed of 1662 bp, and encoded a protein of approximately 36 kDa with a region that resembled a signal sequence. The deduced protein contains the sequences of EGIP-C, EGIP-D, and EGIP-A in that order, followed by the sequence for an unidentified EGIP-like polypeptide. When expressed in Escherichia coli as a fusion protein with beta-galactosidase, the product for the cDNA was specifically recognized by a rabbit antibody raised against EGIP-D that had been purified from embryos. Characteristic amino acid residues were found around the N-terminus and the C-terminus of each EGIP sequence, suggesting a specific processing mechanism for the generation of the individual EGIPs from the precursor. RNA-blot analysis revealed the presence of EGIP mRNA in unfertilized eggs. The level of this mRNA decreased gradually after fertilization, began to increase dramatically after the onset of gastrulation, and continued to increase through the pluteus stage. Genomic Southern-blot analysis suggested that this gene is present as a single copy. A homology search showed that the EGIP cDNA has a similarity to the cDNA for SpEGF2 which was cloned as a gastrula-specific gene in another sea urchin, Strongylocentrotus purpuratus.
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PMID:Molecular cloning of a cDNA that encodes the precursor to several exogastrula-inducing peptides, epidermal-growth-factor-related polypeptides of the sea urchin Anthocidaris crassispina. 770 69

The mechanism that establishes the maternally determined animal-vegetal axis of sea urchin embryos is unknown. We have analyzed the cis-regulatory elements of the SpHE gene of Strongylocentrotus purpuratus, which is asymmetrically expressed along this axis, in an effort to identify components of maternal positional information. Previously, we defined a regulatory region that is sufficient to provide correct nonvegetal expression of a beta-galactosidase reporter gene (Wei, Z., Angerer, L. M., Gagnon, M. L., and Angerer, R. C., Dev. Biol. 171, 195-211, 1995). We have now analyzed this region intensively in order to determine if the spatial pattern is controlled by nonvegetal-positive activities or by vegetal-negative activities. The regulatory sequences, except the basal promoter, were mutated by either deletion or sequence replacement. None of these mutations resulted in ectopic beta-gal expression in vegetal cells, showing that no single negative cis element is responsible for the lack of vegetal SpHE transcription. Surprisingly, even short segments of the regulatory region containing only several identified cis elements also direct nonvegetal expression. Furthermore, the SpHE basal promoter functions effectively in vegetal cells in combination with cis-acting elements derived from the PMC-specific gene, SM50. We conclude that the spatial pattern of SpHE transcription is achieved by multiple positive activities concentrated in nonvegetal cells. The vegetal expression of SM50 also is regulated only by positive activities (Makabe, K. W., Kirchhamer, C. V., Britten, R. J., and Davidson, E. H., Development 121, 1957-1970, 1995). A chimeric promoter containing both SpHE and SM50 regulatory sequences is active ubiquitously, suggesting that these regulators are not reciprocally repressive. These observations suggest a model in which the SpHE and SM50 genes are activated by separate sets of positive maternal activities concentrated, respectively, in nonvegetal and vegetal domains of the early embryo.
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PMID:Multiple positive cis elements regulate the asymmetric expression of the SpHE gene along the sea urchin embryo animal-vegetal axis. 922 75