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W Engel

Publications and source records attributed to W Engel.

At least 127 records · Page 7Linked to original sources
PubMed1994

Expression and chromosomal mapping of the gene encoding the human histone H1.1.

The expression of a human histone H1 isoform (H1.1) was studied in several human tissues. Northern blot analysis has revealed that this gene is expressed in testis and thymus, but not in other human tissues. In this report, we demonstrate that the expression of the histone H1.1 gene in human testis is restricted to early round spermatids that belong to the fraction of postmeiotic sperm cells. Transcripts hybridizing with the human H1.1 gene could not be detected in testis of mouse, rat, bull or boar. Southern blot analysis with human genomic DNA, DNA from different Old World monkeys (chimpanzee, orangutan, gorilla and rhesus monkey) and DNA from several mammalian species has revealed that the histone H1.1 gene is highly conserved in higher primates, whereas no cross-hybridization can be detected with DNA from other mammalian species such as mouse, rat, hamster or bull. In a previous report, the human histone H1.1 gene and other H1 genes (H1.2-H1.5, H1t) were assigned to chromosome 6 by polymerase chain reaction analysis using human-rodent cell hybrid DNA; fluorescence in situ hybridization indicated that these genes form part of a major gene cluster on the short arm of chromosome 6. We have confirmed the localization of histone H1.1 to chromosome 6 and have regionally assigned the locus to 6p21.3 by radioactive in situ hybridization.

Blotting, Southern↗
PubMed1994

A human cDNA coding for the Leydig insulin-like peptide (Ley I-L).

cDNA clones for the human Leydig insulin-like peptide (Ley I-L) have been isolated and characterized. The nucleotide sequence of the 743-bp cDNA includes an incomplete 7-bp 5'-noncoding region, an open reading frame of 393 bp, and a 343-bp 3'-noncoding region. By primer extension analysis, the transcription start site was determined as being 14-bp upstream of the translation start site. The underlying gene is expressed in the testis but not in other organs. From the cDNA sequence, it can be deduced that the Ley I-L protein is synthesized as a 131-amino-acid (aa) preproprotein and that it contains a 24-aa signal peptide. Comparison of the pro Ley I-L protein with members of the insulin-like hormone superfamily predicts that the biologically active hormone, after proteolytic processing of the C peptide, consists of a 31-aa long B chain and a 26-aa long A chain, and that it has a molecular weight of 6.25 kDa.

Amino Acid Sequence↗
PubMed1994

Disturbances of nuclear condensation in human spermatozoa: search for mutations in the genes for protamine 1, protamine 2 and transition protein 1.

During spermiogenesis, the successive replacement of the somatic histones by basic proteins, the transition proteins and protamines, allows normal sperm nuclear condensation. It was suggested that disturbances in nuclear condensation may result in male infertility. Here we report the first molecular analysis of the structure of three genes which code for germ cell-specific nuclear proteins, namely protamine 1 (PRM1), protamine 2 (PRM2) and transition protein 1 (TNP1) in infertile men with disturbed sperm chromatin condensation. In 36 infertile men whose spermatozoa showed a positive reaction with aniline blue, which is an indication for the presence of histones in the nuclei, the complete nucleotide sequences of the coding regions and 5' and 3' untranslated regions of the three genes were evaluated. In addition, 10 infertile patients with oligoasthenoteratozoospermia were studied in the same way, as well as nine infertile patients whose spermatozoa showed a reduction of the protamine 2 content. We did not detect any mutation in the three genes in any of the patients. We assume that the disturbances in the sperm chromatin condensation of our patients, and those described in the literature, are not primarily due to mutations in the genes for PRM1, PRM2 and TNP1.

Base Sequence↗
PubMed1993

Isocyanines and pseudoisocyanines as a novel class of potent noradrenaline transport inhibitors: synthesis, detection, and biological activity.

Noradrenaline, the neurotransmitter of the sympathetic nervous system, is removed from the extracellular space by both neuronal and extraneuronal transport mechanisms. In the past, further investigation of the extraneuronal type of noradrenaline transporter was severely hampered by the lack of potent inhibitors. Here, we describe the synthesis of various novel noradrenaline transport inhibitors which belong to the chemical class of isocyanine and pseudoisocyanine dyes. The biological activity of these compounds was investigated in a tissue culture system (Caki-1 cells). 1,1'-Diisopropyl-2,4'-cyanine, 1,1'-diethyl-2,2'-cyanine, and 1-ethyl-1'-isopropyl-2,2'-cyanine turned out as the most potent inhibitors of the extraneuronal noradrenaline transport known so far. At 100 nmol/L, these compounds diminished extraneuronal noradrenaline transport by about 95%. Their IC50's were below 20 nmol/L. In addition, a rapid and sensitive method (based on HPLC with fluorometric detection) to measure these compounds in body fluids is reported.

Animals↗
PubMed1993

Cloning of a cDNA for a novel insulin-like peptide of the testicular Leydig cells.

We have isolated complementary DNA clones coding for a novel member of the insulin-like hormone super-family from a boar testis cDNA library. Northern blot analysis and in situ hybridization revealed that the gene is expressed exclusively in prenatal and postnatal Leydig cells. We have tentatively proposed the name Leydig insulin-like (Ley I-L) for the gene and its encoded protein. The Leydig insulin-like protein is synthesized as a 131-amino acid preproprotein, which contains a 24-amino acid signal peptide. Comparison of the deduced amino acid sequence of pro-Leydig insulin-like protein with members of the insulin-like hormone superfamily predicts that the biologically active protein, after proteolytic processing of the C-peptide, consists of a 32-residue-long B-chain and a 26-residue-long A-chain and has a molecular size of 6.25 kDa.

Amino Acid Sequence↗
PubMed1993

A conserved 8 bp motif (GCYATCAY) in the 3'UTR of transition protein 2 as a putative target for a transcript stabilizing protein factor.

The 3'UTR of the transition protein 2 gene of several mammalian species was sequenced and the transcript level of this gene was determined by Northern blots. In all species tested so far, a Northern blot detectable transcript level was associated with the presence of a conserved 8 bp motif (GCYATCAY) 50 bp downstream of the stop codon. RNA-bandshift experiments indicate that this region is capable of binding a cytosolic protein factor from rat testis. These findings support our hypothesis that the low transcript level of the transition protein 2 gene in human is due to insufficient storage of the mRNA as ribonucleic/protein particle.

Animals↗
PubMed1993

Characterization of BIBN 99: a lipophilic and selective muscarinic M2 receptor antagonist.

The present study was designed to characterize the receptor selectivity profile of the novel muscarinic M2 receptor antagonist BIBN 99 (5,11-dihydro-8-chloro-11-[[4-[3-[(2,2-dimethyl-1- oxopentyl)ethylamino]propyl]-1-piperidinyl]acetyl]-6H- pyrido[2,3-b][1,4]benzodiazepin-6-one). In radioligand binding studies BIBN 99 showed high affinity for m2/M2 sites (pKi = 7.52/7.57), intermediate affinity for m4 sites (pKi = 6.76) and low affinity for m1/M1 (pKi = 5.97/6.17), m3/M3 (pKi = 6.11/6.04) and m5 sites (pKi = 5.84). Functional studies in vitro showed BIBN 99 to be a competitive antagonist and to have an 11- to 25-fold higher affinity for M2 receptors than for putative M1 receptors in the rabbit vas deferens or M3 receptors in guinea-pig trachea. In vivo studies revealed that BIBN 99 is able to cross the blood-brain barrier, and although showing an approximately 3-fold higher affinity for M2 binding sites BIBN 99 appeared to be 7- to 18-fold less potent than AF-DX 116 in inhibiting muscarinic agonist or vagally induced bradycardia in rats and guinea-pigs. The results show that BIBN 99 is the first lipophilic muscarinic M2 receptor antagonist to have remarkable M2 versus M1 selectivity (30-fold). In addition, BIBN 99 possesses central nervous system activity and only minor peripheral cardiac effects.

Animals↗
PubMed1993

Therapeutic potential of CNS-active M2 antagonists: novel structures and pharmacology.

Clinical trials with muscarinic agonists or acetylcholine esterase inhibitors for the treatment of Alzheimer's dementia have shown disappointing or equivocal results. An alternative treatment of this disease is the development of drugs which enhance the release of acetylcholine. It is believed, that of the five muscarinic receptor subtypes so far identified in the brain, M2 receptors are located presynaptically in the cortex and hippocampus and upon stimulation inhibit the release of acetylcholine. Based on this hypothesis, we initiated a drug discovery program with the aim of identifying selective and centrally active M2 antagonists which are capable of enhancing cholinergic transmission. These efforts resulted in the successful design and synthesis of novel muscarinic antagonists able to cross the blood brain barrier. Moreover, these compounds show few peripheral effects and possess a superior M2 versus M1 selectivity. The prototype of this novel class of M2 selective compounds, BIBN 99, could be a valuable tool to test the hypothesis that lipophilic M2 antagonists show beneficial effects in the treatment of cognitive disorders.

Animals↗
PubMed1993

Chromosome studies in in-vitro fertilization patients.

Human fertility problems may be due to chromosomal aberrations in one or both partners. In couples asking for in-vitro fertilization (IVF) the question arises as to whether chromosomal analysis is necessary. We analysed the karyotypes of 72 couples attending our clinic for IVF. Normal chromosomes were found in 131 individuals. One male was found to be a carrier of a Robertsonian translocation t(14q;21q), a second male had a reciprocal translocation t(2;4)(q14;p15) and 11 females exhibited sex chromosome mosaicism. A single cell aberration was demonstrated in 26% (38/144) of all individuals studied. These results clearly show that chromosomal analysis should be performed in couples asking for IVF.

Chromosome Aberrations↗
PubMed1992

The bovine protamine 2 gene: evidence for alternative splicing.

Protamine 2 (PRM2) is a low molecular weight arginine-rich protein which is present in haploid spermatogenic cells of human and mouse. Although the bull PRM2 gene is translated and transcribed at low levels, the protein could not be detected. The gene was isolated from a cosmid library and was found to consist of two exons (298 and 50 bp, respectively) interrupted by an intron of 142 bp. As compared to the PRM2 genes of man, mouse and rat the bovine gene lacks a highly conserved sequence coding for the amino acids RLHRIH. Furthermore, primer extension experiments on bull PRM2 mRNA and sequencing of junction fragments revealed alternative splicing of mRNA resulting in two putative isoforms of the protein. The most abundant transcript is spliced at the conserved splice donor site found in exon 1 at position 236 giving rise to an in-frame deletion of 63 bp as compared to the cDNA sequence (Maier et al. (1990) Nucleic Acids Res. 18, 1249-1254). The less abundant longer mRNA was not detectable by radioactive primer extension. The corresponding cDNA was obtained by performing PCR with reverse transcribed bull testis RNA or with a spermatid specific cDNA library. Alternative splicing should result in an addition of 21 nonpolar amino acids in the derived polypeptide and an altered protein conformation and function.

Alternative Splicing↗
PubMed1992

Germ cell-specific expression of a proacrosin-CAT fusion gene in transgenic mouse testis.

Acrosin is a serine proteinase located in a zymogen form, proacrosin in the acrosome of the sperm. It is released as a consequence of the acrosome reaction and is believed to be the most important enzyme in the fertilization process. In the mouse, the proacrosin gene is transcribed premeiotically in spermatocytes, but protein biosynthesis starts in haploid spermatids and is restricted to the emerging acrosome. Four lines of transgenic mice harboring 2.3 kb of 5' untranslated region of the rat proacrosin gene fused to the CAT-reporter gene were generated by microinjection of fertilized eggs. The chimeric gene was found to be present in 10-100 copies per genome in the different strains. The 5' untranslated region of rat proacrosin gene could properly direct CAT-gene expression to spermatocytes and CAT-mRNA translation to round spermatids as it is known for mouse proacrosin gene. However, CAT protein is not restricted to the acrosome; rather, it is distributed in the spermatid cytoplasm. This could be due to the lack of DNA sequences for a hydrophobic leader peptide that have been found in all mammalian proacrosins studied until now but that was not present in transgene. It can be concluded from our results that cis-acting sequences required for tissue specific proacrosin expression reside on a 2.3-kb restriction fragment and are conserved in the proacrosin genes of mouse and rat.

Acrosin↗
PubMed1992

The gene for human transition protein 2: nucleotide sequence, assignment to the protamine gene cluster, and evidence for its low expression.

We have isolated the gene for transition protein 2 (TNP2) from a human cosmid clone that contains the genes for protamines 1 and 2. A nucleotide sequence of 1776 bp that comprises 268 bp of the 5'-noncoding region, 400 bp of exon 1, 849 bp of an intron, 17 bp of exon 2, and 242 bp of the 3'-noncoding region was determined. A modified CAT box, a TATAA box, and two possible polyadenylation sites were identified. Transcripts in testicular RNA could be detected only by RT-PCR and RNase protection assays. By direct sequencing of the PCR products, a cDNA sequence was established. It can be deduced from these results that, in contrast to other mammalian genes, the human TNP2 gene is expressed at a very low level. The human gene differs from that of other mammalian species by the absence of a conserved GCCATCAC nucleotide sequence in the 3'-untranslated region. Since both protamine genes are known to be localized on chromosome 16p13.3, this chromosomal localization holds true for the human TNP2 gene as well. The genes for both protamines and TNP2 are arranged in a DNA stretch of 13 kb.

Amino Acid Sequence↗
PubMed1992

The nucleotide sequence of boar transition protein 2 (TNP2) cDNA and haploid expression of the gene during spermatogenesis.

A cDNA clone coding for boar transition protein 2 (TNP 2) was isolated from a randomly primed cDNA library of boar testis. Sequence analysis revealed an open reading frame of 414 bp (corresponding to 138 amino acids), 33 bp of the 5' untranslated and about 300 bp of the 3' untranslated region. As compared to TNP 2 of mouse and rat, similarity with TNP 2 of the boar is approximately 70% at the nucleotide level and only about 40% on the basis of amino acid sequence. The similarity between boar and bull TNP2 is 77% and 64%, respectively. Northern blot experiments with RNA of different boar tissues and in situ hybridization on mature boar testis sections revealed testis-specific expression of the TNP 2 gene which is restricted to haploid germ cells. Hybridization experiments of boar TNP2 cDNA with testicular RNA of boar, bull, rat and mouse revealed decreasing intensities of the hybridization signals. With human testicular RNA no hybridization could be obtained.

Amino Acid Sequence↗