Biomedical subjects

P V Guillot

Publications and source records attributed to P V Guillot.

13 recordsLinked to original sources

PubMed2000

Targeting of human eNOS promoter to the Hprt locus of mice leads to tissue-restricted transgene expression.

Phenotypic heterogeneity of the endothelium arises from cell type-specific differences in gene expression. An understanding of the mechanisms that underlie differential gene expression would provide important insight into the molecular basis of vascular diversity. In standard transgenic assays, multiple copies of heterologous DNA cassettes are randomly integrated into the mouse genome, resulting in significant line-to-line variation in expression. To overcome these limitations, we have targeted a single copy of a transgene that contains 1,600 bp of the human endothelial nitric oxide synthase (eNOS) promoter coupled to the LacZ reporter gene to the X-linked hypoxanthine phosphoribosyltransferase (Hprt) locus of mice by homologous recombination. The transgene was inserted in either of the orientations relative to that of the Hprt gene. In mice derived from multiple embryonic stem (ES) cell clones, the expression pattern was limited to a subset of endothelial cells, cardiomyocytes, and vascular smooth muscle cells. These findings suggest that Hprt locus targeting is a feasible tool for studying endothelial cell-restricted gene regulation.

Animals↗

PubMed1999

Characterization of the mouse von Willebrand factor promoter.

Expression of the von Willebrand factor (vWF) gene is restricted to the endothelial and megakaryocyte lineages. Within the endothelium, expression of vWF varies between different vascular beds. We have previously shown that the human vWF promoter spanning a region between -2182 (relative to the start site of transcription) and the end of the first intron contains information for environmentally responsive, vascular bed-specific expression in the heart, skeletal muscle, and brain. In the present study, we cloned the mouse vWF (mvWF) promoter and studied its function in cultured endothelial cells and transgenic mice. In transient transfection assays, the mvWF gene was found to be regulated by distinct mechanisms in different endothelial cell subtypes. In independent lines of transgenic mice, an mvWF promoter fragment containing DNA sequences between -2645 and the end of the first intron directed endothelial cell-specific expression in the microvascular beds of the heart, brain, and skeletal muscle as well as the endothelial lining of the aorta. In 1 line of mice, reporter gene activity was also detected in bone marrow megakaryocytes. Taken together, these findings suggest that both the mouse and human vWF promoters are regulated by vascular bed-specific mechanisms.

Animals↗

PubMed1999

Mice selected for differences in sensitivity to a benzodiazepine receptor inverse agonist vary in intermale aggression.

Brain gamma-aminobutyric acid (GABA) levels are involved in intermale aggression in mice. It was therefore expected that animals genetically selected for their sensitivity to the convulsive effects of methyl beta-carboline-3-carboxylate (beta-CCM; BS, beta-CCM sensitive, and BR, beta-CCM resistant), a benzodiazepine (BZ) inverse agonist that specifically binds to the BZ site on the GABA-A receptor complex, would differ in their levels of aggressive behavior. Using two different aggression tests, in two independent experiments, we showed that BS mice are more aggressive than BR animals. The precise mechanisms underlying the observed line differences in beta-CCM sensitivity and aggression remain to be determined.

Aggression↗

PubMed1999

A vascular bed-specific pathway.

The endothelial nitric oxide synthase (eNOS) gene is induced by a variety of extracellular signals under both in vitro and in vivo conditions. To gain insight into the mechanisms underlying environmental regulation of eNos expression, transgenic mice were generated with the 1,600-bp 5' flanking region of the human eNos promoter coupled to the coding region of the LacZ gene. In multiple independent lines of mice, transgene expression was detected within the endothelium of the brain, heart, skeletal muscle, and aorta. beta-galactosidase activity was consistently absent in the vascular beds of the liver, kidney, and spleen. In stable transfection assays of murine endothelial progenitor cells, the 1,600-bp promoter region was selectively induced by conditioned media from cardiac myocytes, skeletal myocytes, and brain astrocytes. Cardiac myocyte-mediated induction was partly abrogated by neutralizing anti-platelet-derived growth factor (PDGF) antibodies. In addition, promoter activity was upregulated by PDGF-AB. Analysis of promoter deletions revealed that a PDGF response element lies between -744 and -1,600 relative to the start site of transcription, whereas a PDGF-independent cardiac myocyte response element is present within the first 166 bp of the 5' flanking region. Taken together, these results suggest that the eNos gene is regulated in the cardiac endothelium by both a PDGF-dependent and PDGF-independent microvascular bed-specific signaling pathway.

Animals↗

PubMed1998

Intermale aggression, GAD activity in the olfactory bulbs and Y chromosome effect in seven inbred mouse strains.

The capacity to attack a passive standard opponent in a resident-intruder test and the GAD activity in the olfactory bulbs were measured in 140 male mice from seven different inbred mouse strains. The effect of the non-pseudo autosomal region of the Y-chromosome (YNPAR) on these two phenotypes has also been investigated using a quartet of reciprocal strains congenic for the YNPAR. A strong negative correlation was found between the two variables but the YNPAR is not involved. This result suggests that males of more attacking strains have a lower olfactory threshold, making the olfactory discrimination of the opponent easier and its identification as a stranger more efficient.

Aggression↗

PubMed1998

Neuronal and behavioral differences between Mus musculus domesticus (C57BL/6JBy) and Mus musculus castaneus (CAST/Ei).

Previous studies have demonstrated that classical inbred strains of laboratory mice do not exhibit large genetic distances when simple sequence repeats (SSRs) are used to test for their polymorphisms whereas mice from wild origin exhibit high polymorphisms (more than 90%) for these sequence when compared with classical inbred strains of laboratory mice. The difference between Mus musculus castaneus and C57BL/6J reaches 98% and F1s male and female are fertile. These two properties pave the way for gene mapping derivating segregating generations between these strains. The phenotypical characteristics of Mus musculus castaneus have not been investigated, unfortunately. The first screening of Mus musculus castaneus and C57BL/6By was carried out for sensorial and motor development, spontaneous behavior in new environment, paw preference, maternal behavior, aggression in two different situations and time to learn escape in a water maze. Morphometry of hippocampus and weight of the male reproductive organs for measures that have been reported to be correlated with several of the examined behavior are also reported. The authors tested also reactivity to one drug (beta-CCM) revealing seizure proneness. The two strains differ for 69% of the reported measures. Comparison to other strains for the same measures obtained in the laboratory for identical tests with mice reared in identical situations provided the mean to compare Mus musculus castaneus with a large set of more or less traditional mice. This strain has the most extreme position for 80% of the comparisons.

Aggression↗

PubMed1998

A mutation in the connexin 50 (Cx50) gene is a candidate for the No2 mouse cataract.

PURPOSE: The No2 cataractous mouse mutant displays a bilateral, congenital, hereditary nuclear opacity of the ocular lens. The aim of this work was to identify and subsequently screen an optimal candidate gene for a mutation correlated and consistent with the observed phenotype. METHODS: The No2 cataract was mapped in relation to genes and microsatellite markers by crossing to the wild mouse strain Mus spretus and then backcrossing to the inbred strain C3H/ HeH. The Cx50 (MP70) protein coding region and flanking sequences were amplified from normal parental as well as heterozygous and homozygous mutant genomic DNAs. These PCR products were then sequenced directly. Sequence data was corroborated by restriction analysis of PCR products. RESULTS: Mapping of the No2 cataract placed it in the vicinity of Gja8, the gene encoding connexin 50 (MP70), a major component of lens fiber gap junctions. Amplification and subsequent sequencing of the Cx50 protein coding regions revealed a single A-->C transversion within codon 47. This sequence change resulted in the creation of an HhaI restriction endonuclease restriction site, allowing for corroboration of the sequence data via restriction analysis using this enzyme. The sequence alteration is also predicted to result in the nonconservative substitution of alanine (Ala) for the normally encoded aspartic acid (Asp) at this position within the polypeptide. CONCLUSIONS: The identified mutation in Gja8 is both correlated and consistent with the cataract observed in the No2 mouse mutant, making it an ideal candidate for the cataract. This study provides the first evidence that a mutation in a lens connexin can result in congenital hereditary cataract, highlighting the importance of lens connexins in maintaining lens transparency.

Animals↗

PubMed1996

Olfaction, GABAergic neurotransmission in the olfactory bulb, and intermale aggression in mice: modulation by steroids.

A model to explain individual differences in mice for the propensity to attack male conspecifics is proposed. In the first part of the paper, the relation between olfaction and intermale aggression is discussed emphasizing the importance of olfactory cues provided by the opponent and their subsequent processing by the attacking male. The physiological role of GABA in the olfactory pathway is presented in the second part of the paper. The third part investigates the possible modulating action of steroids on the GABA-A receptor complex, intermale aggression, and olfaction. We hypothesize that at least part of the individual differences in the propensity to attack may be explained by a differential olfactory recognition and discrimination of the opponent as a stranger through a differential processing threshold of the olfactory cues provided by the urine of the opponent. A possible modulation of this threshold by steroids, especially testosterone, is also discussed.

Aggression↗

PubMed1996

Hippocampal morphology in the inbred mouse strains NZB and CBA/H and their reciprocal congenics for the nonpseudoautosomal region of the Y chromosome.

The effects of the nonpseudoautosomal region of the Y chromosome (YNPAR) on hippocampal morphology have been investigated in the inbred mouse strains NZB/BINJ and CBA/H, using comparisons between the two parentals and their respective congenics N.H-YNPAR and H.N-YNPAR. Results obtained depend upon the hippocampal variable measured. YNPAR had no effect on the sizes of the stratum oriens, hilus, or mossy fiber terminal fields (both suprapyramidal and intra- and infrapyramidal). However, in interaction with the strain background, it affected the strata lacunosum-moleculare, radiatum, and pyramidale. Possible relationships among gene(s), mossy fiber terminal fields, and intermale aggression are discussed.

Aggression↗

PubMed1996

Intermale aggression and dark/light preference in ten inbred mouse strains.

The capacity of males to attack a passive standard opponent in a resident-intruder test and the preferences in a dark/light choice situation were measured in 200 male mice from 10 different inbred mouse strains. Large strain differences were found for all variables recorded, i.e., the proportion of attacking males, the time spent in the brightly lit box, and the number of transitions between the lit and the dark boxes. A strong negative correlation was found between the first two variables. This result suggests that males of more attacking strains have a higher level of anxiety but do not differ for their level of activity. An involvement of GABA as mediating factor is suggested.

Aggression↗

PubMed1995

Y chromosomal effects on hippocampal mossy fiber distributions in mice selected for aggression.

The influence of the non-pseudoautosomal region of the Y chromosome (YNPAR) on the sizes of the hippocampal intra- and infrapyramidal mossy fiber (IIPMF) terminal fields were examined in wild house mice. For this purpose selection lines for short attack latency (SAL), long attack latency (LAL), and their respective congenics for the YNPAR were used. We found an incremental effect of the (non-aggressive) LAL YNPAR, combined with an additive effect of the line background on the sizes of the IIPMF terminal fields. In contrast, only the line background affected attack latency. The implications of this finding for the previously observed correlation between the size of the IIPMF and aggression in male house mice are discussed.

Aggression↗

PubMed1995

Intermale aggression tested in two procedures, using four inbred strains of mice and their reciprocal congenics: Y chromosomal implications.

Indications of a role for the nonpseudoautosomal region of the Y chromosome (YNPAR) in intermale attack behavior have been demonstrated by Maxson's group using C57BL/10 (B10) and DBA/1 (D1) inbred mouse strains and their reciprocal congenics. Carlier and Roubertoux' group, using CBA/H (H) and NZB/B1NJ (N) mice, did not find such a YNPAR effect. For the two research groups, however, not only were the parental strains different, but also the rearing conditions and testing methods. The divergent conclusions drawn may therefore have been due either to genetic variation or to environment-related variables. We carried out two experiments to investigate these alternatives. The N and H strains were raised and tested according to the experimental design used by Maxson's group (homogeneous set test) and the D1 and B10 strains were raised and tested according to the experimental design of Carlier and Roubertoux' group (standard opponent test). Considering all studies together, the YNPAR effect appeared in both sets of mice only when using the homogeneous set test. This raises the question of what environmentally related variables are involved in the YNPAR effect on intermale attack. One strong hypothesis is that the different types of opponents in each experimental design send differing olfactory signals, which, in turn, differentially affect the capacity to elicit intermale attack behavior.

Aggression↗

PubMed1994

Hippocampal mossy fiber distributions and intermale aggression in seven inbred mouse strains.

The capacity to initiate attack behavior against a passive standard opponent was measured in 140 male mice belonging to seven different inbred mouse strains. Large strain differences were found, which strongly correlated with the size of the hippocampal intra- and infrapyramidal mossy fibers terminal fields. These results, combined with those obtained from earlier experiments, point to a possible modulating role of the hippocampus in the regulation of attack behavior in male mice.

Aggression↗