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Biomedical subjects

S Fabre

Publications and source records attributed to S Fabre.

At least 37 records · Page 2Linked to original sources
PubMed2000

Identification of functional PDZ domain binding sites in several human proteins.

TIP-15 was previously identified as a cellular protein that can bind to the C-terminal end of the HTLV-1 Tax protein via its two PDZ domains. The sequence of the N-terminal part of TIP-15 is identical to that of the synaptic protein PSD-95. Both proteins are likely to be produced from the same gene by alternative splicing. Whereas expression of the PSD-95 mRNA was detected only with brain RNAs, that of TIP-15 was detected with RNAs from thymus, brain, skeletal muscle and Jurkat cells. The TIP-15 protein exhibits an apparent molecular weight of 40 kD and is weakly expressed in T cell lines. A two-hybrid screen performed with TIP-15 as bait revealed the presence of a PDZ binding site (PDZ-BS) in the following proteins: Lysyl tRNA synthetase, 6-phosphogluconolactonase (6-GPL), Stress-activated protein kinase 3 (SAPK3), NET-1, Diacylglycerol kinase zeta, MTMR1, MCM7, and hSec8. The sequence at the C-terminal ends of these proteins matches the X-S/T-X-V-COOH consensus previously defined for PDZ-BSs, with the exception of 6-GPL and SAPK3 which include a leucine as the C-terminal residue. For Lysyl tRNA synthetase, NET1, MTMR1 and hSec8, binding to TIP-15 was confirmed by co-immunoprecipitation experiments performed with the extracts of transfected COS7 cells. These results show the existence of functional PDZ-BSs in these proteins, but future studies will be necessary to establish whether or not TIP-15 represents a physiological partner. The significance of the presence of a PDZ-BS in these various proteins is discussed with respect to their function.

Amino Acid Sequence↗
PubMed1999

Transcriptional interferences between normal or mutant androgen receptors and the activator protein 1--dissection of the androgen receptor functional domains.

We investigated the interferences of the normal or mutated androgen receptor with the activator protein-1 (AP-1) by assessing their effects on transcriptional activity in CV-1 cells. A luciferase reporter gene was constructed downstream from either a promoter for the mouse vas deferens protein, or a trimerized 12-O-tetradecanoyl phorbol-13-acetate-response element site whose transcriptions are activated by androgen and 12-O-tetradecanoyl phorbol-13-acetate, a potent AP-1 activator. The blockade of dephosphorylation by protein phosphatases identifies the protein phosphatases that modulate the AP-1/androgen receptor cross-talk. Using engineered or naturally occurring androgen receptor mutants that are responsible for complete or partial androgen insensitivity syndromes, we defined the subregions involved in the cross-talk of the androgen receptor with the AP-1 factors. First, it appears that the 188 first amino acids of the N-terminal domain of the androgen receptor are necessary to obtain a full transrepression. Second, a functional and intact ligand binding domain is critical for the modulation of androgen/AP-1 pathway interactions. Third, normal DNA binding capacity of the androgen receptor is not required. Two mutants at positions 568 and 581 of the DNA binding domain demonstrate that the transactivation and transrepression functions of the androgen receptor can be dissociated. Collectively, these data indicate that several segments of the androgen receptor are involved in cross-talk with the AP-1 pathway. Mutations within the DNA binding domain of the androgen receptor highly impair these interferences.

Aldehyde Reductase↗
PubMed1999

[Acquired jejunal and ileal diverticula (Meckel's excluded)].

Acquired jejuno-ileal diverticulosis are rare (0.1 to 1.4%) but their complications are non exceptional (6 to 13%) with a death rate which can reach 40% in older patients. From a histological view, acquired diverticulosis differ from congenital ones by an absent muscular tunic. Complications consist in, by descending order: diverticulitis, perforation (7%), acute bowel obstruction (3%), intestinal hemorrhage (2.7%) mostly massive, malabsorption of fat, protein, macrocytic anaemia, intestinal tumors same as found in small, bowel. The treatment of small bowel diverticulosis becomes surgical only when complicated. It consists in the strict resection of the complicated diverticulosis area, respecting the asymptomatic diverticulosis. Prophylaxis of the complications is based on healthy diet habits against stasis, bowel pressure using antispasmodics, intestinal disinfectants, residue free diet, and against infection (oral tetracyclines).

Adult↗
PubMed1998

The C-terminus of the HTLV-1 Tax oncoprotein mediates interaction with the PDZ domain of cellular proteins.

Infection by HTLV-1 has been correlated with the appearance of various proliferative or degenerative diseases. Some of these disorders have been observed in transgenic mice expressing the Tax protein, which is known to transactivate various viral and cellular promoters through interactions with several transcription factors. In this study we show that the C-terminus of this viral oncoprotein represents a motif permitting binding of Tax to the PDZ domains of several cellular proteins. A two-hybrid screen with Tax as bait indeed yielded complementary DNAs coding for six proteins including PDZ domains. Two of them correspond to truncated forms of the PSD-95 and beta1-syntrophin proteins, another clone codes for a protein homologous to the product of the C. elegans gene lin-7. The other three clones code for new human members of the PDZ family of cellular proteins. The interaction of Tax with the products of these clones was confirmed by immunoprecipitation assays in mammalian cells, and analysis of various mutants of Tax established the importance of the C-terminal amino acids for several of these interactions. These data suggest that Tax could perturb the normal function of targeted cellular proteins by strongly interacting with their PDZ domains.

Amino Acid Sequence↗
PubMed1998

Hypocalcemia following thyroid surgery: incidence and prediction of outcome.

Postoperative hypocalcemia is a common and most often transient event after extensive thyroid surgery. It may reveal iatrogenic injury to the parathyroid glands and permanent hypoparathyroidism. We prospectively evaluated the incidence of hypocalcemia and permanent hypoparathyroidism following total or subtotal thyroidectomy in 1071 consecutive patients operated during 1990-1991. We then determined in a cross-sectional study which early clinical and biochemical characteristics of patients experiencing postoperative hypocalcemia correlated with the long-term outcome. Postoperative calcemia under 2 mmol/l was observed in 58 patients (5. 4%). In 40 patients hypocalcemia was considered severe (confirmed for more than 2 days, symptomatic or both). At 1 year after surgery five patients (0.5%) had persistent hypocalcemia. We found that patients carried a high risk for permanent hypoparathyroidism if fewer than three parathyroid glands were preserved in situ during surgery or the early serum parathyroid hormone level was </= 12 pg/ml, the delayed serum calcium levels </= 8 mg/dl, or the delayed serum phosphorus level >/= 4 mg/dl under oral calcium therapy. When one or more of these criteria are present, long-term follow-up should be enforced to check for chronic hypocalcemia and to avoid its severe complications by appropriate supplement therapy.

Cross-Sectional Studies↗
PubMed1997

Ubiquitous transcription factors NF1 and Sp1 are involved in the androgen activation of the mouse vas deferens protein promoter.

Transcription of the mouse vas deferens protein (MVDP) gene is stimulated by androgens and we have previously shown that in a 162 bp fragment, located at position -121 to +41, a TGAAGTtccTGTTCT sequence functions as an androgen-dependent enhancer. To determine which factors are involved in the hormonally regulated MVDP gene transcription, we have used DNase I footprinting and band-shift assays to examine in vitro binding of proteins to the enhancer and promoter sequences and have determined the functional significance of the recognized DNA sequences in transient transfection assays. Studies using recombinant proteins such as the DNA binding domain of the androgen receptor (AR-DBD) and Sp1, and crude cellular extracts from T47D and vas deferens epithelial cells (VDEC) showed that in addition to AR-DBD, the transcriptional activators NF1 and Sp1 interact with the -121/+41 fragment in a specific manner. Transient transfection assays revealed that site-directed mutations in the NF1 and Sp1 binding elements strongly reduced (NF1) or abolished (Sp1) androgen induced expression. The results demonstrate that the -121/+41 sequence is a composite site for the androgen receptor mediated transactivation of the MVDP gene.

Aldehyde Reductase↗
PubMed1996

Protein kinase C pathway potentiates androgen-mediated gene expression of the mouse vas deferens specific aldose reductase-like protein (MVDP).

Transcription of the mouse vas deferens protein (MVDP) gene, a member of the aldo-keto reductase superfamily, is stimulated by androgens via the androgen responsive element (ARE) located in the proximal promoter (-111 to -97). We investigated interaction between androgens and the protein kinase C (PKC) signalling pathway. Transcriptional regulation was determined by analysis of chloramphenicol acetyltransferase (CAT). T47D cells were transiently transfected with 5' flanking MVDP DNA promoter sequences (-1804 to +41; -510 to +41 and -121 to +41) fused to the reporter (CAT) gene. Androgen-induced transcriptional activity can be enhanced from 6 (1.8 and 0.5 kb MVDP-CAT constructs) to 18 fold (0.16 kb MVDP-CAT construct), in a time and dose-dependent manner, by the PKC activator 12-o-tetradecanoylphorbol-13 acetate (TPA). A mutation in the proximal ARE abolished both androgen and TPA-dependent gene enhancement. TPA influenced minimally MMTV promoter in T47D cells and MVDP promoter in CV1 cells suggesting that the effects of the PKC activator are probably promoter and cell-specific. In contrast, activation of protein kinase A (PKA) via addition of dibutyryl-cAMP (db-cAMP) reduced androgen induction of the MVDP gene.

Aldehyde Reductase↗
PubMed1995

Characterization of the promoter of the gene for a mouse vas deferens protein related to the aldo-keto reductase superfamily: effect of steroid hormones and phorbol esters.

Mouse vas deferens protein (MVDP) is a member of the aldo-keto reductase family regulated by androgens. The expression of a hybrid gene containing the promoter of the MVDP gene and the chloramphenicol acetyl transferase (CAT) gene coding region was analyzed in two cell lines that do not normally express the MVDP gene: T47D and CV1 cells. A small region of the promoter (-121 to +41) was able to direct significant expression of the reporter gene in both cell lines. Additional elements, between -510 and -121 modulate basal expression in a cell-dependent manner. Interestingly, the 162 bp fragment serves as an androgen-dependent enhancer, and mutation of the consensus ARE sequence located between positions -111 and -97 resulted in a loss of androgen response in both cell lines. Additional elements, upstream of the enhancer, modulate induction positively or negatively in relation to the cell line used. The expression of different MVDP-CAT constructs was more effectively induced by androgens than by glucocorticoids at physiological hormonal concentrations. In addition to the 162 bp enhancer, sequences upstream of -510 were also required for specific androgen regulation. Phorbol 12-myristate 13-acetate (TPA) had no effect on basal activity of the 1.8 kb MVDP-CAT construct but strongly enhanced the induction by androgens.

Alcohol Oxidoreductases↗
PubMed1995

Vas deferens epithelial cells in subculture: a model to study androgen regulation of gene expression.

The understanding of androgen-regulated gene expression requires a cell cultures system that mimics the functions of cells in vivo. In the present paper we have examined a vas deferens epithelial cell subculture system. Cultured vas deferens epithelial cells have been shown to exhibit polarized properties characteristic of functioning epithelia and to display a high level of androgen receptors. Incubation of cells with androgen caused a decrease in cellular androgen receptor mRNA that was time-dependent. Total suppression was observed after 24h of exposure to androgen. By contrast, incubation of vas deferens epithelial cells with androgen resulted in a threefold increase in the cellular content of androgen receptor protein, as assayed by ligand binding. In response to androgens, vas deferens epithelial cells expressed mouse vas deferens protein mRNA (MVDP mRNA). Maximum expression of the MVDP gene, at both mRNA and protein levels, was observed after 24h of androgen induction. DEAE-dextran transfection conditions were defined using the MMTV-CAT gene in vas deferens epithelial cells in a dose- and time-dependent manner. No induction was seen when fragments of the MVDP promoter region were cloned directly in front of the CAT gene and transiently transfected into vas deferens epithelial cells. It was found that cotransfection of cells with MVDP-CAT gene and transfection of cells with MVDP-CAT constructs and with an androgen receptor expression vector resulted in a small but consistent androgen-dependent increase in reporter gene activity. Transiently transfected vas deferens epithelial cells are a suitable model with which to study the effect of androgen on gene regulatory elements.

3T3 Cells↗
PubMed1995

Antimicrobial activities of indolocarbazole and bis-indole protein kinase C inhibitors. II. Substitution on maleimide nitrogen with functional groups bearing a labile hydrogen.

New compounds, structurally related to the potent protein kinase C inhibitor staurosporine, and substituted on the imide nitrogen with a functional group bearing a labile hydrogen (hydroxymethyl, amino, hydroxy), were synthesized. Their in vitro inhibitory potencies towards protein kinase C and protein kinase A showed that N-hydroxymethyl and N-hydroxy substitution, unlike alkyl substitution, can provide efficient protein kinase C inhibitors. The antimicrobial activities of these new compounds against Streptomyces chartreusis and Streptomyces griseus, Bacillus cereus, Escherichia coli, Candida albicans and Botrytis cinerea were examined. They proved to be inactive against E. coli and two fungi. The results suggest that there is no link between in vitro inhibition of protein kinase C and inhibition of growth and sporulation of the two Streptomyces tested. Unlike indolocarbazole maleimides, bis-indole maleimides are active against the two Streptomyces species.

Carbazoles↗
PubMed1994

[A new generation of tranquilizing agents].

The newer anxiolytics include compounds whose the molecular structure, the mechanisms, and the pharmacological properties are heterogeneous. Nevertheless, the most of them have clinical and adverse effects like to the most known: buspirone, after the commercial shrinking for hepatic toxicity of alpidem. These anxiolytics are efficacious against generalized anxiety disorder, like the benzodiazepines. The principal interest consists in minimal adverse effects and the safety of the use. These compounds have not a sedative effect, do not induce rebound, dependence, abuse and withdrawal, do not impair the psychomotor, cognitive and memory performances. The big ratio efficacy/tolerance allows to use them in long treatments, old subjects, alcoholic and drug-addicted patients. Nevertheless to become ideal anxiolytics, these compounds must be efficacious in other anxious disorders and increase the efficacy of various psychotherapies.

Anti-Anxiety Agents↗
PubMed1994

Identification of a functional androgen response element in the promoter of the gene for the androgen-regulated aldose reductase-like protein specific to the mouse vas deferens.

Mouse vas deferens protein (MVDP), a member of the aldo-keto reductase superfamily, is exclusively produced in the epithelial cells of the deferent duct under androgenic regulation. To better understand androgenregulated MVDP gene expression, the location and sequences of androgen response elements (AREs) in the 5'-flanking DNA were determined. Sequence analysis revealed two putative AREs as follows: one between positions -1186 and -1171 (distal ARE) and the other between -111 and -97 (proximal ARE). To study hormonal regulation, fragments of the MVDP promoter region, extending from residue -1804 to +41, were linked to the chloramphenicol acetyltransferase (CAT) reporter gene and cotransfected with a human androgen receptor expression vector into T47D cells in a transient expression assay. A minimal region (-121 to +41) was identified as being sufficient for androgen-regulated gene expression. A mutation in proximal ARE almost completely abolished androgen induction of CAT. One copy of the sequence TGAAGT tcc TGTTCT, cloned in the opposite orientation in front of the thymidine kinase promoter, confers androgen responsiveness to the CAT reporter gene. Androgen transcriptional activity was not detected with the distal ARE. The data provide strong evidence that transcriptional regulation of the MVDP gene occurs via the sequence TGAAGT tcc TGTTCT.

Aldehyde Reductase↗
PubMed1994

Indolocarbazole protein kinase C inhibitors from rebeccamycin.

Structural modifications were carried out on rebeccamycin, an antitumour antibiotic, to obtain analogues. The inhibitory potencies of these analogues against protein kinase C are compared. The method described represents an alternative route to the staurosporine aglycone, a potent protein kinase C inhibitor.

Aminoglycosides↗
PubMed1994

Antimicrobial activities of indolocarbazole and bis-indole protein kinase C inhibitors.

The antimicrobial activities of twenty-two substances structurally related to staurosporine, aglycone in the indolocarbazole and bis-indole series were examined against Streptomyces chartreusis and Streptomyces griseus, Bacillus cereus, Escherichia coli, Candida albicans and Botrytis cinerea. Inhibition of sporulation was examined also on the two species of Streptomyces. Unlike literature reports for efficient protein kinase inhibitors, staurosporine and K-252a, no evident correlation could be found either between protein kinase inhibitory potencies and inhibition of sporulation of the Streptomyces species, or protein kinase inhibitory potencies and growth of all microorganisms tested. A weak activity against C. albicans was observed for the chloro-indolocarbazole compounds as already reported for structurally related substances from the cyanobacterium Tolypothrix tjipanasensis.

Alkaloids↗
PubMed1992

The genomic organization and DNA sequence of the mouse vas deferens androgen-regulated protein gene.

The gene for mouse vas deferens protein (MVDP) is expressed, under androgenic control, exclusively in the epithelial cells of the deferent duct. As a first step in correlating cell-specific and hormonal regulations with the structure of the gene, the complete sequence of the MVDP gene (11 kb) and 0.5 kb of the 5' flanking region have been determined. The size range for the 10 exons is 78 to 168 bp, whereas that of introns is 292 to 2833 bp. A major site of transcription is located on an A residue 46 nucleotides upstream from the A of the ATG initiation codon. A TATA (CATAA) box, a CAAT box, a GC-rich motif and a (5'-TGTTCT-3') element that closely resembles the consensus sequence of the androgen response elements are present in the 5' flanking region of the MVDP gene.

Aldehyde Reductase↗