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W Engel

Publications and source records attributed to W Engel.

At least 91 records · Page 5Linked to original sources
PubMed1996

Sequence analysis of the conserved protamine gene cluster shows that it contains a fourth expressed gene.

Structural data are presented on the protamine gene cluster (PGC) of human, mouse, rat, and bull. By restriction mapping we demonstrate that the organization of the protamine cluster is conserved throughout all four species, i.e., the genes are situated in a head to tail arrangement in the order: protamine 1-protamine 2-transition protein 2. Further, we established the nucleotide sequence of the entire human PGC (25 kb in total) and the 3' portion of the rat protamine cluster (PRM2 and TNP2 genes and intergenic region). In addition, a 1 kb fragment of the bovine and murine protamine cluster, situated between PRM2 and TNP2, was sequenced. This fragment is conserved regarding sequence, position, and orientation in all species examined, and was classified as likely coding region by gene recognition program GRAIL. Using the rat fragment as a probe in RNA blots, we detected a testis-specific signal of about 0.5 kb. Finally, we demonstrate a high density of Alu elements, both full and fragmented copies, in the human PGC and discuss their localization with respect to evolutionary and functional aspects.

Animals↗
PubMed1996

Cloning, expression, and chromosomal localization of the rat mitochondrial capsule selenoprotein gene (MCS): the reading frame does not contain potential UGA selenocysteine codons.

The mitochondrial capsule selenoprotein (MCS) is a selenium-containing polypeptide. It is one of three proteins that are important for the maintenance and stabilization of the crescent structure of the sperm mitochondria. In this paper, we report the isolation and characterization of the rat MCS cDNA and gene. The cDNA contains a reading frame for a 145-amino-acid protein and it lacks the UGA codons, which have been found in the reading frame of the mouse MCS cDNA and have been presumed to encode the selenocysteine in the amino terminal of the deduced mouse amino acid sequence. The deduced amino acid sequence of the rat and mouse MCS shows a high level of homology (79%). The rat MCS gene contains two exons; the intron sequence interrupts the 5' untranslated sequence at the same position as in the mouse MCS gene. The transcription start site is located 184 bp upstream of the translation start site. Alignment of the 5'-flanking regions of the mouse and rat genes reveals that the first 400 nucleotides upstream of the transcription start site exhibit an overall sequence similarity of 73%. This conserved region contains no TATA or CAAT box motifs. Northern blot analysis indicates that the MCS mRNA is detectable only in the testis after day 30 of postnatal development. Moreover, in situ hybridization revealed that the rat MCS gene is mainly expressed in round spermatids. From the analysis of mouse-rat cell hybrids that segregate rat chromosomes, the MCS gene was assigned to rat chromosome 2.

Amino Acid Sequence↗
PubMed1996

Human Y chromosome azoospermia factors (AZF) mapped to different subregions in Yq11.

In a large collaborative screening project, 370 men with idiopathic azoospermia or severe oligozoospermia were analysed for deletions of 76 DNA loci in Yq11. In 12 individuals, we observed de novo microdeletions involving several DNA loci, while an additional patient had an inherited deletion. They were mapped to three different subregions in Yq11. One subregion coincides to the AZF region defined recently in distal Yq11. The second and third subregion were mapped proximal to it, in proximal and middle Yq11, respectively. The different deletions observed were not overlapping but the extension of the deleted Y DNA in each subregion was similar in each patient analysed. In testis tissue sections, disruption of spermatogenesis was shown to be at the same phase when the microdeletion occurred in the same Yq11 subregion but at a different phase when the microdeletion occurred in a different Yq11 subregion. Therefore, we propose the presence of not one but three spermatogenesis loci in Yq11 and that each locus is active during a different phase of male germ cell development. As the most severe phenotype after deletion of each locus is azoospermia, we designated them as: AZFa, AZFb and AZFc. Their probable phase of function in human spermatogenesis and candidate genes involved will be discussed.

Chromosome Mapping↗
PubMed1996

Are there genetic risks associated with microassisted reproduction?

Of all the techniques available for microassisted reproduction, the direct injection of individual sperm cells or spermatids into the cytoplasm of the oocyte (ICSI) is the most invasive, through which any possible selection against sperm cells with genomic defects would be excluded. It has, however, been shown that such a possible selection is present neither in the female genital tract nor at the zona pellucida. Selection against genetic-based defects occurs after the fertilization of the oocyte, during both embryonic and fetal development. Based on the data to date, it can be assumed that ICSI would not result in either a significant increase in genetic-based diseases, or in an increase in the number of infertile males. If, however, mutations of X-chromosomal or Y-chromosomal genes should play a major role in male fertility disorders, one could expect, over generations, an increase, though probably very slight, in the number of males with such disorders.

Animals↗
PubMed1996

Interphase chromosome arrangement in Sertoli cells of adult mice.

Sertoli cells of adult male laboratory mice were examined with a number of banding techniques and by nonradioactive in situ hybridization applying different repetitive DNA probes. All banding methods revealed the typical features of mouse Sertoli cells, i.e., a central nucleolus, usually with two chromocenters associated at diametrically opposed sides in which the centromeric regions of the chromosomes are clustered. Silver staining as well as in situ hydridization with rDNA labeled part of the chromocenters and the nucleolus, indicating transcriptional activity of at least some of the nucleolus organizer regions. In situ hybridization with X- and Y-specific DNA probes showed both sex chromosomes to be undercondensed in Sertoli cells This decondensation suggests expression of sex chromosomal genes in Sertoli cells. While the X chromosome appeared to occupy a central position near one of the chromocenters, the Y chromosome was found at the periphery of the nucleus in the majority of cells. Hybridization with telomeric sequences resulted in strong labeling of the chromocenters and dispersed signals at the nuclear periphery.

Animals↗
PubMed1996

Five novel mutations in the L1CAM gene in families with X linked hydrocephalus.

Five novel mutations have been identified in the gene encoding L1CAM, a neural cell adhesion protein, in families with X linked hydrocephalus (XHC). Interestingly, all five mutations are in the evolutionarily highly conserved Ig-like domains of the protein. The two frameshift mutations (52insC and 955delG) and the nonsense mutation (Trp276Ter) most probably result in functional null alleles and complete absence of L1CAM at the cell surface. The two missense mutations (Tyr194Cys and Pro240Leu) may considerably alter the structure of the L1CAM protein. These data provide convincing evidence that XHC is genetically extremely heterogeneous.

Abnormalities, Multiple↗
PubMed1996

Neuropeptide Y and the nonpeptide antagonist BIBP 3226 share an overlapping binding site at the human Y1 receptor.

Neuropeptide Y (NPY) is a 36-amino acid peptide that exhibits actions on the cardiovascular system and the central nervous system. NPY can regulate blood pressure, psychomotor function, anxiety, food intake, and endocrine secretions. BIBP 3226, the first potent and selective nonpeptide antagonist at the NPY Y1 receptor, was designed by mimicking the carboxyl-terminal structure of NPY. We investigated the interaction of NPY and BIBP 3226 with the human Y1 receptor at the molecular level. Alanine mutants at positions Y100, D104, W288, and H298 of the human Y1 receptor showed no or significantly reduced binding for NPY but were not affected in their ability to bind BIBP 3226. Receptors with alanine mutations at positions W163, F173, Q219, N283, F286, and D287 showed reduced binding for both NPY and BIBP 3226. Mutations at other positions were tested (H105, S170, L174, V178, D200, D205, S206, H207, S210, T212, T280, T284, N289, H290, and Q291) and did not affect the binding of NPY or BIBP 3226. The human Y1 receptor mutant Y211A showed no affinity for BIBP 3226 but retained wild-type affinity for NPY. Based on these experimental results, a detailed model for the interaction of BIBP 3226 with the human Y1 receptor was developed using a Y1 receptor model and a three-dimensional model of BIBP 3226. The experimental results, supported by modeling studies, clearly suggest that the native ligand (NPY) and the antagonist (BIBP 3226) share an overlapping binding site.

Amino Acid Sequence↗
PubMed1996

Stage and developmental specific gene expression during mammalian spermatogenesis.

Spermatogenesis is a complex developmental process which involves amplification of germinal stem cells, their differentiation into spermatocytes, meiotic division and finally transformation into mature spermatozoa. Therefore, spermatogenesis provides an interesting system for examining the regulation of gene expression during development and differentiation. The genes expressed during spermatogenesis can be divided into two main groups: diploid and haploid expressed genes. In this review, we report about the regulation of expression of a diploid expressed gene, namely the proacrosin gene, and that of a haploid expressed gene, the transition protein 2 gene.

Acrosin↗
PubMed1996

The structures of the bovine and porcine proacrosin genes and their conservation among mammals.

Sperm acrosin is a serine protease that is involved in the recognition, binding and penetration of the sperm of the zona pellucida of the ovum. The bovine and porcine genes were cloned and characterized. Alignment of the intron/exon structure of both genes with the previously characterized human, rat and mouse genes and with other serine protease genes reveals that the coded sequence of the mammalian proacrosin is distributed in 5 exons and the splice junction types are identical to the exons encoding the catalytic domain of other serine protease genes. A comparison of the bovine, porcine, human, guinea pig, rabbit, rat and mouse preproprotein sequences shows that the catalytic domain is highly conserved, while the sequence of the proline rich domain is very variable among the species, ranging from 28.9% to 68.8%.

Acrosin↗
PubMed1995

Labeling of neuropeptide Y receptors in SK-N-MC cells using the novel, nonpeptide Y1 receptor-selective antagonist [3H]BIBP3226.

The binding of tritium-labelled BIBP3226, N2-(diphenylacetyl)-N-[(4-hydroxy-phenyl)methyl]-D-arginine amide, to human neuroblastoma SK-N-MC cells was investigated. [3H]BIBP3226 reversibly binds to neuropeptide Y receptors of the Y1 subtype expressed in SK-N-MC cells with a KD of 2.1 +/- 0.3 nM (mean +/- S.E.M., n = 3) and a Bmax of 58,400 +/- 1100 sites/cell. Non-specific binding did not exceed 30% of the total radioactivity bound at KD. In competition experiments [3H]BIBP3226 is concentration-dependently displaced by neuropeptide Y and its peptide analogues with an affinity pattern neuropeptide Y = [Leu31, Pro34]neuropeptide Y >> neuropeptide Y-(18-36). This rank order of potencies is consistent with the interaction of [3H]BIBP3226 with neuropeptide Y receptors of the Y1 subtype. Therefore, [3H]BIBP3226 can be used as selective ligand to study neuropeptide Y Y1 receptors.

Arginine↗
PubMed1995

Translational control in spermatogenesis.

Translational silencing phenomena during spermatogenesis in the two model systems Drosophila and mouse are reviewed. Cis-acting sequences were identified in both species that are necessary for translational repression. While in Drosophila these elements so far have only been found in the 5' untranslated region (5' UTR), in the mammals such regions were identified both in the 5' as well as in the 3' UTR. In all cases, RNA-binding proteins interact with these regions, yet their specific role in the observed negative regulation of translation has to be established.

Animals↗
PubMed1995

Restriction fragment length polymorphisms at the apoprotein genes AI, CIII and B-100 and in the 5' flanking region of the insulin gene as possible markers of coronary heart disease.

Several sequence variations were examined for being endogenous "risk markers" in the development of CHD. The "markers" in this study included: the PstI-SstI RFLPs in the apo AI-CIII gene cluster, the EcoRI-MspI RFLPs in the apo B100 gene and the SstI RFLP in the 5' flanking region of the insulin gene. The study population comprised 700 individuals of German origin. A strong association of these "markers" to the disease phenotype predicts their loss in healthy individuals with ages above that of the prevalent incidence of CHD. In contrast, these "markers" should accumulate in diseased persons. A significant age-dependent selection was observed for the EcoRI RFLP in the apo B100 gene. This was the case when the allele and genotype frequencies of healthy old individuals were compared with those of newborns. In contrast, no RFLP showed significant differences in allele and genotype distributions between patients defined by coronary angiography and controls. In the group of patients, but not controls, several RFLP genotypes were found to be associated with significantly higher serum levels of cholesterol and triglycerides. This was true in the case of serum cholesterol comparing the genotypes S1S2 with those of S1S1 (p = 0.05) observed for the SstI polymorphic site in the 3' noncoding region of the apo CIII gene. Significantly higher levels of triglycerides were found within the heterozygous patients P1P2 (p = 0.045) and S1S2 (p = 0.02) than in the homozygotes P1P1 and S1S1 for the PstI-SstI RFLPs at the apo AI-CIII gene cluster.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

The rat Prm3 gene is an intronless member of the protamine gene cluster and is expressed in haploid male germ cells.

We have cloned and sequenced the cDNA of a novel gene from the rat protamine gene cluster. This gene, preliminarily referred to as Prm3, is intronless and resides between the genes for protamine 2 and transition protein 2. Prm3 is transcribed from the same strand as these genes and is expressed in haploid stages of spermatogenesis. The 410-bp-long cDNA possesses an ORF, coding for a putative 104-amino acid polypeptide with a high content of glutamic acid.

Amino Acid Sequence↗
PubMed1995

Evidence for an unusual ZW/ZW'/ZZ sex-chromosome system in Scardinius erythrophthalmus (Pisces, Cyprinidae), as detected by cytogenetic and H-Y antigen analyses.

Fifty-seven individuals of the European cyprinid fish species Scardinius erythrophthalmus were sexed by gonad histology, and their karyotypes were analyzed by Giemsa staining and C-banding. The chromosome number in somatic metaphase plates was 2n = 50. Karyotypes of all gonadal male animals were identical, consisting of 48 small meta- or submetacentric chromosomes and a pair of large metacentric chromosomes (ZZ males). Of the 33 gonadal females, 16 had a karyotype similar to the males' (ZW' females) and 17 had a heteromorphic pair of chromosomes, including a large metacentric Z chromosome and a small acrocentric W chromosome (ZW females). H-Y antigen typing with cells obtained from a variety of tissues revealed that the homogametic ZZ males were H-Y negative and the heterogametic ZW females were H-Y positive in all tissues tested. In contrast, ZW' females showed no expression of the H-Y antigen in somatic cells but were H-Y positive in ovarian cells. These results suggest that the ZW/ZW'/ZZ sex chromosomes of S. erythrophthalmus represent an unusual system of sex determination and that H-Y antigen expression is coupled with the heterogametic sex. Whether the ZW' individuals are indeed heterogametic females or actually sex-reversed ZZ males, in which chromosomal sex determination is overruled by external factors, is discussed.

Animals↗
PubMed1995

DNA-protein binding studies in the 5' flanking region of rat proacrosin gene which is transcribed in diploid germ cells.

The proacrosin gene is transcribed in diploid spermatogenic cells and translated in haploid round spermatids. In order to evaluate sequences which are involved in proacrosin gene transcription, DNA-protein interactions were analyzed in 1.2 kb of the 5'flanking region of the rat gene. 13 protein binding sites were identified by DNase I footprinting using nuclear extracts from rat testis and brain, respectively. Five footprints (F1, F3, F7, TS2, TS3) which suggest an interaction with testis specific nuclear factors were further examined by gel retardation assays. Three testis specific binding sites (F1, F7, TS2, located 472bp, 697bp and 1004bp upstream of ATG, respectively) could be identified with both methods. The binding site F1 contains a motif which is similar to a testis specific footprint found in mouse protamine 1 gene. The nucleotide sequence of F7 contains the recognition motif of an isoform of the transcription factor GATA1, which is expressed in testis. Furthermore F1 and F7 are located in that part of the 5'flanking region of the proacrosin gene, which can direct proacrosin gene expression in germ cells of male transgenic mice.

Acrosin↗
PubMed1995

Molecular cloning and characterization of the bovine and porcine outer dense fibers cDNA and organization of the bovine gene.

Outer dense fibers (ODF) or accessory fibers are filamentous structures of the sperm tail of many eumetozoan organisms endowed with internal fecundation. The bovine and porcine cDNA of an outer dense fiber protein was cloned, sequenced and compared to the previously characterized human and rat cDNA sequences. The coding sequences and the 5' and 3' untranslated regions of the ODF cDNAs are highly conserved. A comparison of the bovine, porcine, human and rat ODF protein sequences revealed that the protein displays a high degree of similarity, ranging from 87% to 98%. The ODF protein is rich in cysteine and contains the C.X.P. repeat at the C-terminal which is different in number among mammalian species. All the 27 cysteine residues in the ODF sequence except those in the C.X.P. repeat are conserved in the four species. We report here also the organization of the bovine ODF gene which is similar to that of human and rat. The transcription start site in the bovine ODF gene is localized 98 bp upstream of the translation start site. Alignment of the 5' flanking region of bovine ODF with the rat gene reveals that the first 130 nucleotides upstream of the transcription start site exhibit an overall sequence similarity of 83%. This conserved region contains a TATA-like box (TTTAAA) and binding sites for AFT/CREB and EGR-1 transcription factors.

Amino Acid Sequence↗