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PubMed1995

The gene encoding human splicing factor 9G8. Structure, chromosomal localization, and expression of alternatively processed transcripts.

The 9G8 factor is a 30-kDa member of the SR splicing factor family. We report here the isolation and characterization of the human 9G8 gene. This gene spans 7745 nucleotides and consists of 8 exons and 7 introns within the coding sequence, thus contrasting with the organization of the SC35/PR264 or RBP1 SR genes. We have located the human 9G8 gene in the p22-21 region of chromosome 2. The 5'-flanking region is GC-rich and contains basal promoter sequences and potential regulatory elements. Transfection experiments show that the 400-base pair flanking sequence has a promoter activity. Northern blot analysis of poly(A)+ RNA isolated from human fetal tissues has allowed us to identify five different species, generated by alternative splicing of intron 3, which may be retained or excised as a shorter version, as well as the use of two polyadenylation sites. We also show that the different isoforms are differentially expressed in the fetal tissues. The persistence of sequences between exon 3 and 4 results in the synthesis of a 9G8 protein lacking the SR domain which is expected to be inactive in constitutive splicing. Thus, our results raise the possibility that alternative splicing of intron 3 provides a mechanism for modulation of the 9G8 function.

Alternative Splicing↗
PubMed1995

Mouse alpha 1- and beta 2-syntrophin gene structure, chromosome localization, and homology with a discs large domain.

The syntrophin family of dystrophin-associated proteins consists of three isoforms, alpha 1, beta 1, and beta 2, each encoded by a distinct gene. We have cloned and characterized the mouse alpha 1- and beta 2-syntrophin genes. The mouse alpha 1-syntrophin gene ( > 24 kilobases) is comprised of eight exons. The mouse beta 2-syntrophin gene ( > 33 kilobases) contains seven exons, all of which have homologues at the corresponding position in the alpha 1-syntrophin gene. Primer extension analysis reveals two transcription initiation sites in the alpha 1-syntrophin gene and a single site in the beta 2-syntrophin gene. The sequence immediately 5' of the transcription start sites of both genes lacks a TATA box but is GC-rich and has multiple putative SP1 binding sites. The alpha 1-syntrophin gene is located on human chromosome 20 and mouse chromosome 2, while the beta 2-syntrophin gene is on human chromosome 16 and mouse chromosome 8. Analysis of the amino acid sequence of the syntrophins reveals the presence of four conserved domains. The carboxyl-terminal 56 amino acids are highly conserved and constitute a syntrophin unique domain. Two pleckstrin homology domains are located at the amino-terminal end of the protein. The first pleckstrin homology domain is interrupted by a domain homologous to repeated sequences originally found in the Drosophila discs-large protein.

Amino Acid Sequence↗
PubMed1998

Growth regulation of the expression of mouse cDNA and gene encoding a serine/threonine kinase related to Saccharomyces cerevisiae CDC7 essential for G1/S transition. Structure, chromosomal localization, and expression of mouse gene for s. cerevisiae Cdc7-related kinase.

Saccharomyces cerevisiae CDC7 encodes a serine/threonine kinase required for G1/S transition of the yeast cells. We previously reported human and Xenopus cDNAs encoding CDC7-related kinases and suggested the possibility that chromosomal replication of higher eukaryotes may be regulated through conserved mechanisms involving Cdc7-related kinases. Here we report a murine cDNA and gene (muCdc7) encoding a serine/threonine kinase related to CDC7. The predicted coding frame for the longest cDNA for muCdc7 consists of 564 amino acids, which shares 46, 77, and 93% identity, respectively, with those of budding yeast, Xenopus, and human in kinase conserved domains. The chromosomal gene for muCdc7, located at the band 5E5 on the mouse chromosome 5, consists of 12 exons, and its exon/intron organization shares some similarity with that of other protein kinases including Cdk and cAMP-dependent kinase. Transcription of muCdc7, initiated at multiple sites over the 370-base pair promoter region, is repressed in the resting state and is induced at the G1/S boundary after growth factor stimulation in a growth factor-dependent cell line. Transient transfection assays indicated that a 231-base pair segment of the muCdc7 promoter containing three putative E2F binding sites and one Sp1 site but lacking TATA sequence is sufficient for response to growth stimulation.

Amino Acid Sequence↗
PubMed2000

The mouse Na(+)-sulfate cotransporter gene Nas1. Cloning, tissue distribution, gene structure, chromosomal assignment, and transcriptional regulation by vitamin D.

NaSi-1 is a Na(+)-sulfate cotransporter expressed on the apical membrane of the renal proximal tubule and plays an important role in sulfate reabsorption. To understand the molecular mechanisms that mediate the regulation of NaSi-1, we have isolated and characterized the mouse NaSi-1 cDNA (mNaSi-1), gene (Nas1), and promoter region and determined Nas1 chromosomal localization. The mNaSi-1 cDNA encodes a protein of 594 amino acids with 13 putative transmembrane segments, inducing high affinity Na(+)-dependent transport of sulfate in Xenopus oocytes. Three different mNaSi-1 transcripts derived from alternative polyadenylation and splicing were identified in kidney and intestine. The Nas1 gene is a single copy gene comprising 15 exons spread over 75 kilobase pairs that maps to mouse chromosome 6. Transcription initiation occurs from a single site, 29 base pairs downstream to a TATA box-like sequence. The promoter is AT-rich (61%), contains a number of well characterized cis-acting elements, and can drive basal transcriptional activity in opossum kidney cells but not in COS-1 or NIH3T3 cells. We demonstrated that 1,25-dihydroxyvitamin D(3) stimulated the transcriptional activity of the Nas1 promoter in transiently transfected opossum kidney cells. This study represents the first characterization of the genomic organization of a Na(+)-sulfate cotransporter gene. It also provides the basis for a detailed analysis of Nas1 gene regulation and the tools required for assessing Nas1 role in sulfate homeostasis using targeted gene manipulation in mice.

Amino Acid Sequence↗
PubMed1987

New murine homeoboxes: structure, chromosomal assignment, and differential expression in adult erythropoiesis.

The nucleotide sequence, chromosomal assignment, and preliminary transcriptional analysis of four murine homeoboxes is presented. Three of these are linked to the Hox-2 gene complex on chromosome 11, whereas the fourth, Hox-4, was assigned to mouse chromosome 12. A comparative analysis of homeobox sequences reveals that two of our sequences represent the previously described Hox-2.3 loci, whereas a third, mh19, could represent the predicted Hox-2.6 locus. Homeoboxes Hox-2.2 and Hox-2.3 are the cognates of two previously reported human homeoboxes that belong to a similar gene cluster on a closely related human chromosome (Chr 17), suggesting that homeoboxes may have been preserved as clusters during evolution. Moreover Hox-4, mh19, and the previously described Hox-1.5 homeobox form a separate subgroup of mammalian homeoboxes (90-92% amino acid and nucleotide homology). All four homeoboxes are expressed in the mouse embryo. Of special interest is the expression of mh19, a 4.2-kb transcript of which appears to be connected to the induced differentiation of Friend erythroleukemia cells.

Amino Acid Sequence↗
PubMed1998

Mouse HNF-3/fork head homolog-1-like gene: structure, chromosomal location, and expression in adult and embryonic kidney.

Screening of a mouse kidney cDNA library with a HNF-3/fork head domain probe revealed cDNA Hfh-1L containing the highly conserved fork head DNA-binding domain. The Hfh1L cDNA shows 92.7% homology at the nucleic acid level with the fork head gene HFH-1 from rat. Southern blot analyses demonstrated that the Hfh-1L gene is highly conserved in a wide variety of species, including goldfish and frog. Sequencing the corresponding genomic clone, we found that the Hfh-1L gene is most likely intronless. By interspecific back-cross analysis, the Hfh-1L gene was localized to mouse chromosome 13. In order to analyze the expression pattern of Hfh-1L, we performed Northern blot analyses and revealed a 2.7-kb transcript in adult kidney and stomach. In situ hybridization experiments of adult mouse kidney showed Hfh-1L expression in the outer medulla of the kidney and the transitional epithelium. In light of the significance of a number of fork head genes in early embryonic development, the pattern of expression during murine embryogenesis was examined by reverse transcriptase-polymerase chain reaction (RT-PCR), and Hfh-1L transcripts were detected in mouse embryos at every stage tested from day 10.5 to 16.5 postconception (p.c.) and in the developing metanephros of 14.5- and 15.5-day p.c. embryos. This expression pattern suggests that the Hfh-1L gene is involved in the development of the kidney.

Amino Acid Sequence↗
PubMed2002

Disruption of centrosome structure, chromosome segregation, and cytokinesis by misexpression of human Cdc14A phosphatase.

In budding yeast, the Cdc14p phosphatase activates mitotic exit by dephosphorylation of specific cyclin-dependent kinase (Cdk) substrates and seems to be regulated by sequestration in the nucleolus until its release in mitosis. Herein, we have analyzed the two human homologs of Cdc14p, hCdc14A and hCdc14B. We demonstrate that the human Cdc14A phosphatase is selective for Cdk substrates in vitro and that although the protein abundance and intrinsic phosphatase activity of hCdc14A and B vary modestly during the cell cycle, their localization is cell cycle regulated. hCdc14A dynamically localizes to interphase but not mitotic centrosomes, and hCdc14B localizes to the interphase nucleolus. These distinct patterns of localization suggest that each isoform of human Cdc14 likely regulates separate cell cycle events. In addition, hCdc14A overexpression induces the loss of the pericentriolar markers pericentrin and gamma-tubulin from centrosomes. Overproduction of hCdc14A also causes mitotic spindle and chromosome segregation defects, defective karyokinesis, and a failure to complete cytokinesis. Thus, the hCdc14A phosphatase appears to play a role in the regulation of the centrosome cycle, mitosis, and cytokinesis, thereby influencing chromosome partitioning and genomic stability in human cells.

Animals↗
PubMed1994

Human Fas ligand: gene structure, chromosomal location and species specificity.

Fas ligand (FasL) is a 40 kDa type II membrane protein belonging to the tumor necrosis factor family, which induces apoptosis by binding to its receptor, Fas. In this report, we isolated the chromosomal gene for human FasL. The human FasL gene consists of approximately 8.0 kb and is split into four exons. The human FasL gene was mapped on chromosome 1q23 by in situ hybridization against human metaphase chromosomes. Human FasL cDNA was isolated by the reverse polymerase chain reaction of mRNA prepared from human activated peripheral blood lymphocytes. Human FasL is a type II membrane protein consisting of 281 amino acids with a calculated M(r) of 31,759. It has an identity of 76.9% at the amino acid sequence level with mouse FasL. Both human and mouse recombinant FasL expressed in COS induced apoptosis in the cells expressing either human Fas or mouse Fas, indicating that FasL fully cross-reacts between human and mouse. A comparison of human and mouse FasL chromosomal genes indicated that a approximately 300 bp sequence upstream of the ATG initiation codon is highly conserved between them. Several transcription cis-regulatory elements such as SP-1, NF-kappa B and IRF-1 were recognized in this region.

Adult↗
PubMedDate not supplied

Structure, chromosomal location, and analysis of the canine Cu/Zn superoxide dismutase (SOD1) gene.

Mutations in Cu/Zn superoxide dismutase (SOD1), a major cytosolic antioxidant enzyme in eukaryotic cells, have been reported in approximately 20% of familial amyotrophic lateral sclerosis (FALS) patients. Hereditary canine spinal muscular atrophy (HCSMA), a fatal inherited motor neuron disease in Brittany spaniels, shares many clinical and pathological features with human motor neuron disease, including FALS. The SOD1 coding region has been sequenced and cloned from several animal species, but not from the dog. We have mapped the chromosomal location, sequenced, and characterized the canine SOD1 gene. Extending this analysis, we have evaluated SOD1 as a candidate for HCSMA. The 462 bp SOD1 coding region in the dog encodes 153 amino acid residues and exhibits more than 83% and 79% sequence identity to other mammalian homologues at both the nucleotide and amino acid levels, respectively. The canine SOD1 gene maps to CFA31 close to syntenic group 13 on the radiation hybrid (RH) map in the vicinity of sodium myo/inositol transporter (SMIT) gene. The human orthologous SOD1 and SMIT genes have been localized on HSA 21q22.1 and HSA 21q21, respectively, confirming the conservation of synteny between dog syntenic group 13 and HSA 21. Direct sequencing of SOD1 cDNA from six dogs with HCSMA revealed no mutations. Northern analysis indicated no differences in steady-state levels of SOD1 mRNA.

Amino Acid Sequence↗
PubMed1998

The human PTFgamma/SNAP43 gene: structure, chromosomal location, and identification of a VNTR in 5'-UTR.

PTF/SNAPc is a multisubunit complex which specifically recognizes the PSEs of small nuclear RNA genes and activates transcription by RNA polymerase II or III. Here we describe the isolation and characterization of genomic clones encoding the human PTFgamma/SNAP43 gene. The gene spans approximately 29 kilobases, and is composed of 9 exons and 8 introns. A major transcription initiation site was identified at the position 58 base pairs upstream of the AUG translation initiator codon on primer extension analysis with HeLa mRNA. The 5' flanking region lacks a typical TATA box but contains many putative binding sites for various transcription factors, such as Sp1, Oct1, NF1, AP1, E2F, and USF. Immediately downstream of the transcription start site, we found a VNTR of a 17-bp sequence rich in (G+C). Four different alleles with two to five copies of the tandem repeat were identified in 10 individuals examined, indicating a high degree of variation at the PTFgamma/SNAP43 locus. In addition, the PTFgamma/SNAP43 gene was mapped to human chromosome 14q22 by fluorescence in situ hybridization.

Base Sequence↗
PubMed2001

Mice with a targeted disruption of the H1t gene are fertile and undergo normal changes in structural chromosomal proteins during spermiogenesis.

H1t is an H1 histone variant unique to late spermatocytes and early spermatids. Using gene targeting and embryonic stem cell technologies, we have produced mice with a disrupted H1t gene. Homozygous H1t-null mice have normal fertility and show no obvious phenotypic consequence due to the lack of this histone. Biochemical and immunohistochemical approaches were used to show that normal changes in chromosomal proteins occurred during spermatid development, including the appearance and disappearance of transition proteins 1 and 2. Both protamines 1 and 2 are present in normal amounts in sonication-resistant spermatid nuclei from H1t-null mice. Analysis of H1 histones by quantitative gel electrophoresis in enriched populations of pachytene spermatocytes and round spermatids showed that the lack of H1t is only partially compensated for by somatic H1s, so that the chromatin of these cells is H1 deficient. Because H1t is thought to create a less tightly compacted chromatin environment, it may be that H1-deficient chromatin is functionally similar to chromatin with H1t present, at least with respect to permitting spermatogenesis to proceed.

Alleles↗
PubMed1989

A new family of mouse homeo box-containing genes: molecular structure, chromosomal location, and developmental expression of Hox-7.1.

Two families of homeo box-containing genes have been identified in mammals to date, the Antennapedia- and engrailed-like homeo boxes, based on the sequence similarity to those from Drosophila. Here, we report the isolation of a homeo box-containing gene that belongs to a new family of which there are at least three related genes in the mouse genome. The homeo box of this new gene shows remarkable similarity to the Drosophila Msh homeo box that we designate as the prototype for this family. The gene maps to the proximal end of mouse chromosome 5 and does not cosegregate with any known homeo box-containing gene. We designate this locus Hox-7.1. In situ hybridizations to mouse embryos at different stages show a unique pattern of expression, as compared to other homeo box-containing genes described thus far. Hox-7.1 transcripts are detected in 9.5-day-old embryos in the neural crest, developing limb bud, and visceral arches. Later, this gene is expressed in regions of the face that are derived from neural crest and in the interdigital mesenchymal tissues in both the fore- and hindlimbs.

Amino Acid Sequence↗
PubMed1983

Sister chromatid exchanges and structural chromosome aberrations in lymphocytes in operating room personnel.

Information on possible chromosomal damage in humans after long-term exposure to trace concentrations of waste anaesthetic gases is scarce. We examined peripheral lymphocytes in operating room personnel for both chromosome aberrations and sister chromatid exchanges (SCE). Following a standardized procedure of cultivation and staining, 30 cells from each person were scored for SCE and 100 cells from each person were examined for chromosome aberrations. A total of 45 persons were examined, representing anaesthetists (n = 15), operating room nurses assisting the surgeon (n = 10), nurses circulating in the operating room (n = 8) and healthy, unexposed controls (n = 12). The median duration of working in the operating room was 102 months, 66 months and 66 months, respectively. Time-weighted concentration levels of 2.5-4.3 p.p.m. of halothane and 25-400 p.p.m. of nitrous oxide were measured in the breathing zones of the anaesthetists during mask anaesthesia. Examination of SCE and chromosome aberrations yielded corresponding qualitative results. With both tests, no statistically significant difference was observed between the four groups of persons. It was concluded that by examination of both SCE and chromosome aberrations in peripheral lymphocytes in operating room personnel, no indication was found of a mutagenic effect of long-term exposure to trace concentrations of waste anaesthetic gases.

Anesthesiology↗