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W Peter

Publications and source records attributed to W Peter.

At least 37 records · Page 2Linked to original sources
PubMed1993

Mouse Oct-1 contains a composite homeodomain of human Oct-1 and Oct-2.

Members of the Oct family of transcription factors specifically interact with the octamer motif, ATGC-AAAT, a regulatory element important for tissue- and cell-specific transcription as well as for the expression of housekeeping genes. Except for Oct-1, all Oct factors are expressed in a temporally and spatially restricted mode during murine development and their number varies in a given cell type. Despite its ubiquitous expression pattern Oct-1 may play a role in murine development. As a first step towards elucidating the role of Oct-1 we report the complementary DNA cloning of the mouse Oct-1 gene. Two large transcripts of 5 and 14 kb are derived from a single gene. The expression patterns of three splicing products of Oct-1 are similar in a number of cells and tissues. In the POU region murine Oct-1 differs in four amino acids from the human homologue and these differences are restricted to helices 1 and 2. Interestingly, two of the four variant amino acids are identical to those in human and mouse Oct-2 and thus the murine Oct-1 homeodomain is intermediary in sequence between human Oct-1 and Oct-2. These two amino acids together with a third one have been shown to be relevant for the interaction between human Oct-1 and herpes simplex virus transactivator VP16. Nevertheless, VP16 interacts albeit weakly with murine Oct-1. We speculate that the differences in the human and mouse Oct-1 homeodomains reflect host-specific differences in protein-protein interactions.

Amino Acid Sequence↗
PubMed1992

Interchain cysteine bridges control entry of progesterone to the central cavity of the uteroglobin dimer.

The progesterone-binding protein uteroglobin has been expressed in Escherichia coli in an unfused, soluble form. Like mature uteroglobin from rabbit endometrium (UG), the E.coli produced uteroglobin (UG1) dimerizes in vitro, forms an antiparallel dimer with Cys3-Cys69' and Cys69-Cys3' disulfide bonds and binds progesterone under reducing conditions. In order to analyze the dimerization and the reduction dependence of progesterone binding in more detail, we separately replaced cysteine 3 and cysteine 69 by serines. Under reducing conditions, both uteroglobin variants (UG1-3Ser and UG1-69Ser) bind progesterone with the same affinity as the wild-type suggesting that both cysteine residues are not directly involved in progesterone binding. In contrast to the wild-type protein, both cysteine variants also bind progesterone with high affinity in the absence of reducing agents. In addition, UG1-3Ser and UG1-69Ser both form covalently linked homodimers. Thus, unnatural Cys69-69' and Cys3-3' disulfide bonds exist in UG1-3Ser and UG1-69Ser, respectively. These data together with computer models based on X-ray diffraction data strongly support the idea that progesterone reaches its binding site located in an internal hydrophobic cavity via a hydrophobic tunnel along helices 1 and 4. Under non-reducing conditions the tunnel is closed by two disulfide bridges (Cys3-Cys69' and Cys69-Cys3') that lie in the most flexible region of the dimer. Reduction or replacement of a cysteine residue enables conformational changes that open the channel allowing progesterone to enter.

Amino Acid Sequence↗
PubMed1991

Identification of residues essential for progesterone binding to uteroglobin by site-directed mutagenesis.

In order to identify amino acids directly involved in progesterone binding to rabbit uteroglobin we have mutated Phe 6, Tyr 21 and Thr 60 by site-directed mutagenesis of the uteroglobin cDNA. These residues have been postulated previously to participate in progesterone binding. High-level expression of the mutated uteroglobin cDNAs in Escherichia coli yields recombinant protein mutants that, like natural uteroglobin, form stable dimers, suggesting that the tertiary structure of the protein has not been altered. Substitution of Phe 6 by Ser or Ala does not change the progesterone binding characteristics. In contrast, replacement of Tyr 21 by Phe or Ala, drastically decreases progesterone binding. In addition, replacement of Thr 60 by Ala reduces the affinity for progesterone by a factor of three. These data suggest a direct interaction of progesterone with these two amino acids and support the idea of direct hydrogen bonding of the carbonyl (C3 and C20) of progesterone with the hydroxyl groups of Tyr 21 and Thr 60, respectively.

Animals↗
PubMed1991

Expression of the uteroglobin promoter in epithelial cell lines from endometrium.

To understand the molecular mechanism of endometrial differentiation we have initiated an analysis of the uteroglobin promoter. Uteroglobin is normally expressed in endometrial tissues under the control of ovarian hormones. In gene transfer experiments with the Ishikawa cell line, derived from a human endometrial adenocarcinoma, we have identified several regions in the promoter of the uteroglobin gene that are responsible for its endometrium-specific expression. To evaluate the generality of these findings, we have begun cloning the promoter regions of potential endometrial markers, including the rat, mouse, and human uteroglobin gene. In the rat, expression of the uteroglobin-like gene, CC10, is dominant in the lung but is also observed in the endometrium of progesterone treated animals. A comparison of the 5'-flanking sequence of the rat and rabbit uteroglobin gene resulted in the detection of similarities and differences that could explain their differential expression in vivo. To substantiate these findings we have established several cell lines from rat endometrium using murine retroviral vectors containing a positive selection marker and various viral oncogenes, such as SV40 large T antigen, adenovirus E1A, and Ha-ras. Cell lines immortalized by SV40 T-antigen were subsequently transformed with the Ha-ras oncogene. Several cell lines exhibit properties of epithelial endometrial cells. Two cell lines generated with a temperature sensitive mutant of the SV40 large T-antigen grow as transformed cells at the permissive temperature, but differentiate upon shifting to the non-permissive temperature. These rat endometrial cell lines should be useful for the analysis of endometrium-specific gene expression and as model systems for endometrial carcinoma.

Animals↗
PubMed1990

Karyotypic characterization of established cell lines derived from a squamous cell carcinoma and an adenocarcinoma of human lung cancers.

Two non-small cell carcinoma cell lines from the major histopathologic groups of human lung cancers have been karyotyped: HS-24 was established from a squamous cell carcinoma, and SB-3 was obtained from a metastasis of a poorly differentiated adenocarcinoma. Endoreduplication is characteristic for both cell lines. Subsequent loss of chromosomes led finally to hypotetraploid karyotypes with modal chromosome numbers of 66-68 and 70-72 for HS-24 and SB-3, respectively. The structural analysis was performed by G- and C-banding. Stable overrepresentation of chromosomes 7, 8, 12, and 16 was found. Both cell lines developed a characteristic set of disomic and stable markers. Chromosomes involved in markers were 1, 2, 5, 6, 10, 11, 16, and 17. Consistent numerical and structural normality for chromosomes 4, 18, and 21 was observed.

Adenocarcinoma↗
PubMed1989

Recombinant rabbit uteroglobin expressed at high levels in E. coli forms stable dimers and binds progesterone.

In order to express uteroglobin in Escherichia coli we have constructed a DNA coding for complete mature rabbit uteroglobin by fusing genomic sequences from the second exon of the gene to an incomplete cDNA. This DNA was inserted into various positions of the polylinker cloning region of pDS expression vectors and the uteroglobin gene was expressed in E. coli by IPTG induction. Four different uteroglobin-derived proteins were produced containing 1, 3, 5 and 7 more N-terminal amino acids than the naturally occurring mature protein. The yield of soluble protein strongly increased with increasing length of the N-terminal additions. Protein and RNA analysis showed that this variation is most likely due to progressively higher translation efficiencies of the larger recombinants. UG7, the most efficiently synthesized recombinant protein, carrying seven additional N-terminal amino acids, was purified and further characterized. Like natural uteroglobin, UG7 forms a dimer and binds progesterone with an affinity indistinguishable to the natural protein. This bacterially produced protein can be used for detailed structure-function investigations of uteroglobin.

Animals↗
PubMed1982

Neurogenic non-adrenergic cutaneous vasodilatation elicited by hypothalamic thermal stimulation in dogs.

Hypothalamic heating in dogs with depleted peripheral adrenergic transmitter stores by means of chronic application of reserpine elicits increase of hindpaw blood flow. The vasodilator response is not affected by alpha- and beta-adrenergic or cholinergic blocking substances, nor by histamine-, or prostaglandin-antagonists. Dopamine and ergometrine produce cutaneous vasoconstriction which is antagonized or prevented by haloperidol. The hypothalamic vasodilator response is abolished after intra-arterial injection of haloperidol, after lumbar sympathetic chain section, or by high doses of hexamethonium. The results indicate neurogenic non-adrenergic control of skin blood flow in thermoregulation possibly acting through inhibition of dopaminergic vasoconstrictor mechanisms.

Animals↗
PubMed1980

[Relation between testosterone levels in sperm and spermatogenesis as well as fertilization performance of young boars].

Testosterone in sperma was measured by means of radio-immuno-assay in 400 ejaculates which had been obtained from 153 young boars aged seven months. Low but significant relationships were found exist between the testosterone level in sperma, on the one hand and sperma concentration, percentage of forward-mobile sperms as well as volume, on the other. Neither relative nor absolute testosterone levels in sperma exhibited any dependence on general body development. Sperma-borne testosterone values in boars, aged seven months, cannot be used for early diagnosis of forthcoming spermatogenetic capacity. However, the fertilization performance of an artificial insemination boar can be predicted as a general trend on the basis of relative testosterone values in sperma. Such general prediction should be used as a point of departure from which to devise objective criteria for the characterisation of fertilizing capability.

Age Factors↗