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M Rossignol

Publications and source records attributed to M Rossignol.

At least 73 records · Page 4Linked to original sources
PubMed1997

The XPB subunit of repair/transcription factor TFIIH directly interacts with SUG1, a subunit of the 26S proteasome and putative transcription factor.

Mutations in the basal transcription initiation/DNA repair factor TFIIH are responsible for three human disorders: xeroderma pigmentosum (XP), cockayne syndrome (CS) and trichothiodystrophy (TTD). The non-repair features of CS and TTD are thought to be due to a partial inactivation of the transcription function of the complex. To search for proteins whose interaction with TFIIH subunits is disturbed by mutations in patients we used the yeast two-hybrid system and report the isolation of a novel XPB interacting protein, SUG1. The interaction was validated in vivo and in vitro in the following manner. (i) SUG1 interacts with XPB but not with the other core TFIIH subunits in the two-hybrid assay. (ii) Physical interaction is observed in a baculovirus co-expression system. (iii) In fibroblasts under non-overexpression conditions a portion of SUG1 is bound to the TFIIH holocomplex as deduced from co-purification, immunopurification and nickel-chelate affinity chromatography using functional tagged TFIIH. Furthermore, overexpression of SUG1 in normal fibroblasts induced arrest of transcription and a chromatin collapse in vivo. Interestingly, the interaction was diminished with a mutant form of XPB, thus providing a potential link with the clinical features of XP-B patients. Since SUG1 is an integral component of the 26S proteasome and may be part of the mediator, our findings disclose a SUG1-dependent link between TFIIH and the cellular machinery involved in protein modelling/degradation.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1997

Substrate specificity of the cdk-activating kinase (CAK) is altered upon association with TFIIH.

The transcription/DNA repair factor TFIIH consists of nine subunits, several exhibiting known functions: helicase/ATPase, kinase activity and DNA binding. Three subunits of TFIIH, cdk7, cyclin H and MAT1, form a ternary complex, cdk-activating kinase (CAK), found either on its own or as part of TFIIH. In the present work, we demonstrate that purified human CAK complex (free CAK) and recombinant CAK (rCAK) produced in insect cells exhibit a strong preference for the cyclin-dependent kinase 2 (cdk2) over a ctd oligopeptide substrate (which mimics the carboxy-terminal domain of the RNA polymerase II). In contrast, TFIIH preferentially phosphorylates the ctd as well as TFIIE alpha, but not cdk2. TFIIH was resolved into four subcomplexes: the kinase complex composed of cdk7, cyclin H and MAT1; the core TFIIH which contains XPB, p62, p52, p44 and p34; and two other subcomplexes in which XPD is found associated with either the kinase complex or with the core TFIIH. Using these fractions, we demonstrate that TFIIH lacking the CAK subcomplex completely recovers its transcriptional activity in the presence of free CAK. Furthermore, studies examining the interactions between TFIIH subunits provide evidence that CAK is integrated within TFIIH via XPB and XPD.

Animals↗
PubMed1997

SUG1, a putative transcriptional mediator and subunit of the PA700 proteasome regulatory complex, is a DNA helicase.

Yeast SUG1 was originally characterized as a transcriptional mediator for the GAL4 transactivator. A similar role in vertebrates was suggested by the ligand-enhanced interaction between mammalian homologues of yeast SUG1 and the ligand-dependent activating domain (AF-2) of nuclear receptors. SUG1 was also shown to be a component of the PA700 regulatory complex of the 26 S proteasome and a member of a large family of putative ATPases. However, no catalytic function has yet been attributed to SUG1. We show here that SUG1 is a 3'-5' DNA helicase whose activity is dependent on an intact ATP binding domain. The sedimentation heterogeneity of mammalian SUG1 suggests that it may be associated with distinct protein complexes and therefore play multiple roles.

Adenosine Triphosphatases↗
PubMed1997

Challenges in assessing risk factors in epidemiologic studies on back disorders.

In epidemiologic studies on musculoskeletal disorders, some risk factors, especially physical load, cannot be determined independently from the worker. Posture, movement and external load are the result both of physical work requirements forced on the worker and of the worker's capacity to adopt particular techniques. Risk factors are also adjusted in relation to the worker's health. This paper presents a dynamic model that links exposure to risk factors for back pain and disability. Its aim is to help identify core elements in exposure assessment strategies for epidemiologic studies on back disorders. In this dynamic model, risk factors are determined relative to health status in order to distinguish between etiological and prognostic factors. Measurement techniques for various risk factors are classified into self-reports, observations, and direct instrumentation. Features of commonly used techniques are discussed with respect to feasibility, accuracy, and precision. In addition, consideration is given to the optimum allocation of measurements taking into account the effects of random and systematic variation in exposure due to tasks, workplaces, and workers.

Back Pain↗
PubMed1997

Cloning, sequencing, and transgenic expression of Podospora curvicolla and Sordaria macrospora eEF1A genes: relationship between cytosolic translation and longevity in filamentous fungi.

We have cloned and sequenced the gene encoding the translation elongation factor eEF1A from two filamentous fungi, Podospora curvicolla and Sordaria macrospora. These fungi are close relatives of Podospora anserina and also show senescence syndromes. Comparison of the sequences of the deduced proteins with that of P. anserina reveals that the three proteins differ in several positions. Replacement of the P. anserina gene by either of the two exogenous genes does not entail any modification in P. anserina physiology; the longevity of the fungus is not affected. No alteration of in vivo translational accuracy was detected; however, the exogenous proteins nonetheless promoted a modification of the resistance to the aminoglycoside antibiotic paromomycin. These data suggest that optimization of life span between these closely related fungi has likely not been performed during evolution through modifications of eEF1A activity, despite the fact that mutations in this factor can drastically affect longevity.

Amino Acid Sequence↗
PubMed1997

Expression in Escherichia coli: purification and characterization of cyclin H, a subunit of the human general transcription/DNA repair factor TFIIH.

The human cyclin H, a protein normally associated with the cyclin-dependent kinase cdk7, was overexpressed in Escherichia coli using a T7 RNA polymerase expression system and further purified to apparent homogeneity. The purified recombinant cyclin H is similar to the endogenous one according to the following criteria: molecular weight, microsequencing and mass spectra studies, ability to interact with cdk7, and regulatory kinase activity. The scale-up of cyclin H purification is described.

Affinity Labels↗
PubMed1997

Plasticity of the mitochondrial genome in Podospora. Polymorphism for 15 optional sequences: group-I, group-II introns, intronic ORFs and an intergenic region.

The mitochondrial chromosome of 15 Podospora anserina and one Podospora comata wild-type strains have been extensively examined for the presence of optional elements and for sequence divergence. Among the P. anserina strains, nine optional sequences were found. By comparing P. anserina with the closely related and weakly interfertile P. comata species, six additional optional sequences were detected. These optional elements correspond to mitochondrial introns belonging to different groups and subgroups (11 cases), intronic open reading frames (two cases), a complex insert and an intergenic region. Although difficult to explain, the distribution of optional mitochondrial sequences among the 15 wild-type isolates of P. anserina is far from random.

Ascomycota↗
PubMed1997

International differences in epidemiology of lung adenocarcinoma.

In Europe, the squamous cell carcinoma is the most frequent non-small cell lung cancer (NSCLC) subtype and until now, no increase in incidence of lung adenocarcinoma (ADC) has been described (except in the Netherlands), in contrast to North America where ADC predominates. Our aim was to compare the percentage of ADC in Montreal (MTL), Canada, with that in Strasbourg (STBG), France. We prospectively identified patients with NSCLC in MTL and in STBG over an 8-month period and described the distribution of NSCLC by sex, age, subtype and smoking history. A total of 172 patients in MTL and 166 in STBG were identified. The male/female ratio was significantly different in STBG (12:1) and in MTL (2:1). The percentage of ADC was significantly higher in MTL (40%) than in STBG (30%). This difference is partly due to the higher number of women with NSCLC in Montreal combined with the predominance of ADC in women. The proportion of ADC decreased with age in STBG, but was similar in each age category in MTL. In STBG, most women with NSCLC had never smoked (69%), in contrast to MTL where only 16% of women had never smoked. In conclusion, ADC is more frequent in MTL than in STBG. This is partly due to the higher number of women with NSCLC in MTL combined with the predominance of ADC in women. The greatest proportion of ADC subtype in the youngest cohorts of men in STBG suggests that ADC may be on the rise in this city.

Adenocarcinoma↗
PubMed1997

Identification of 14 kDa auxin-binding proteins in a tobacco plasma membrane subfraction responsive to auxin.

Auxin binding by tobacco plasma membrane proteins was investigated. After photolabeling with [3H]IAA, 350 polypeptides were resolved on 2D gels and analyzed. Thirteen polypeptides were selected according to physico-chemical criteria. The labeling of three of them was further shown to increase, after treatment of cells with auxin, specifically in that plasma membrane subfraction where the sensitivity to the hormone of the H(+)-ATPase is enhanced by the treatment of cells. These polypeptides were those that exhibited the more specific labeling features according to physico-chemical criteria. They had similar apparent molecular weight (ca 14 kDa) that distinguished them from other auxin-binding proteins described up to now, and exhibited similar amino acid compositions. These 14 kDa polypeptides are proposed to constitute a group of new auxin-binding proteins, potentially involved, within specialized plasma membrane domains, in the stimulation of the proton pump by the hormone.

Amino Acids↗
PubMed1997

A new family of plasma membrane polypeptides differentially regulated during plant development.

Two cDNAs encoding polypeptides identified in a tobacco leaf plasma membrane fraction prepared by phase partitioning were cloned. The deduced polypeptides, P16 and P17, exhibit a striking primary structure, similar to that of P19, a previously cloned plasma membrane polypeptide. Antibodies raised to the recombinant proteins were used to probe the cellular location of P16, P17 and P19 by means of western blotting of sucrose density-gradient fractions; all three polypeptides were found to be located solely at the plasma membrane. Furthermore, P19 antigen accumulated transiently at the time of floral induction while P16 and P17 antigens accumulated towards the end of the life-cycle. These results together with sequence database searches and multiple-sequence alignments suggest that we have identified a new family of plasma membrane polypeptides that (i) are putatively plant specific and (ii) are differentially regulated during plant development. These polypeptides are termed DREPPs for developmentally regulated plasma membrane polypeptides.

Amino Acid Sequence↗
PubMed1997

Cytosolic ribosomal mutations that abolish accumulation of circular intron in the mitochondria without preventing senescence of Podospora anserina.

The filamentous fungus Podospora anserina presents a degeneration syndrome called Senescence associated with mitochondrial DNA modifications. We show that mutations affecting the two different and interacting cytosolic ribosomal proteins (S7 and S19) systematically and specifically prevent the accumulation of senDNA alpha (a circular double-stranded DNA plasmid derived from the first intron of the mitochondrial cox1 gene or intron alpha) without abolishing Senescence nor affecting the accumulation of other usually observed mitochondrial DNA rearrangements. One of the mutant proteins is homologous to the Escherichia coli S4 and Saccharomyces cerevisiae S13 ribosomal proteins, known to be involved in accuracy control of cytosolic translation. The lack of accumulation of senDNA alpha seems to result from a nontrivial ribosomal alteration unrelated to accuracy control, indicating that S7 and S19 proteins have an additional function. The results strongly suggest that modified expression of nucleus-encoded proteins contributes to Senescence in P. anserina. These data do not fit well with some current models, which propose that intron alpha plays the role of the cytoplasmic and infectious Determinant of Senescence that was defined in early studies.

Amino Acid Sequence↗
PubMed1997

Carpal tunnel syndrome: what is attributable to work? The Montreal study.

OBJECTIVE: To estimate the fraction of carpal tunnel syndrome (CTS) that is attributable to work in the total adult population of the island of Montreal. METHODS: The population consisted of 1.1 million people 20-64 years of age, with 73.2% of men and 60.6% of women employed. The rates of first surgery for CTS were compared between occupational groups and the total adult population with the standardised incidence ratio (SIR) method. Rates of surgery for the island of Montreal were obtained from the provincial data base of payments. The occupational history was obtained from telephone interviews of a sample of surgical cases. The attributable fractions in exposed people were calculated with odds ratios (ORs) obtained from logistic regressions with non-manual workers as the control group. RESULTS: The surgical incidence of CTS was 0.9/1000 adults. SIRs for all manual workers were 1.9 (95% confidence interval (95% CI) 1.4-2.5) in men and 1.8 (95% CI 1.4-2.2) in women, and the fractions attributable to work were 76% (95% CI 47-88) and 55% (95% CI 33-69), respectively. Seven occupational groups were identified as having excess risk of surgical CTS, with fractions attributable to occupation ranging from 75% to 99%. CONCLUSION: Among manual workers on the island of Montreal, 55% of surgical CTS in women and 76% in men was attributable to work. Increased risk of surgical CTS was found in seven occupational groups.

Adult↗
PubMed1997

Relationship between selected discourse strategies and student critical thinking.

This study investigated the relationship between use of selected discourse strategies and level of student critical thinking in nursing clinical post-conferences. Selected discourse strategies included: (a) teacher high-level questions, (b) teacher elaboration of student ideas, (c) teacher probing questions, (d) student participation, and (e) student-to-student participation. The level of student critical thinking was defined as the quartile ranking of students (N = 57) on the Watson-Glaser Critical Thinking Appraisal summative measure. It was hypothesized that greater use of discourse strategies would be associated with high-levels of student critical thinking. All discourse strategies were significantly associated (p < .0001) to student quartile ranking for one taping session (Conference II). Further analysis, however, revealed ambiguous patterns of two-way associations. The more consistent findings suggested a conceptual relationship between less student talk and student-to-student talk and high-levels of student critical thinking.

Adult↗
PubMed1997

[Genetic analysis of two cellular degenerations in filamentous fungus Podospora anserina].

The filamentous fungus Podopsora anserina presents an unavoidable arrest of vegetative growth (Senescence) determined by a cytoplasmic and infectious factor. Senescence is correlated with a disorganization of the mitochondrial DNA. This disorganization is caused by an event which is not the appearance of the first defective DNA molecules. These ones are generated constitutively and their accumulation during Senescence requires the presence of an additional factor. Life span of the strains is under nuclear and cytoplasmic genetic control. At least 600 nuclear genes influence longevity. Our analysis focuses on the role of the genes involved in cytosolic translation, since mutations in these genes seem to display the most drastic effects on longevity but also on the structure of the defective mitochondrial DNA molecules that accumulate during Senescence. We have detected in some Podospora anserina mutant strains (permissive strains) the presence of a novel cytoplasmic and infectious determinant that entails an easily discernible phenotype associated with a severe growth alteration (Crippled Growth). This growth alteration is not associated with mitochondrial DNA modifications. Only the strains that have an increased translational accuracy present Crippled Growth. However, the Crippled Growth Determinant is found in all the strains during the stationary phase; it is eliminated from the non permissive strains during the exit of the stationary phase. The mutants, that have an increased translational accuracy, probably lack a factor which is needed to eliminate the determinant when cells enter the growth phase.

Ascomycota↗
PubMed1996

Should the gap be filled between guidelines and actual practice for management of low back pain in primary care? The Quebec experience.

STUDY DESIGN: A prospective cohort study. OBJECTIVES: To describe health services utilization for low back pain in the province of Quebec, Canada, and to compare it with North American guidelines. SUMMARY OF BACKGROUND DATA: The Quebec Task Force and the Agency for Health Care Planning and Research (United States) published guidelines for the management of low back pain in 1987 and 1994, respectively. METHODS: A cohort of 2147 adults with low back pain identified at the Quebec Worker's Compensation Board were selected randomly and observed over 2 years' time for their health care utilization profile. RESULTS: During the study period, 57.8% of the workers still under active care 7 weeks after their back injury had not yet been referred to a specialist. Specialized imaging techniques were obtained by 4.5% of the patients, with a delay of 7 weeks or more in 66% of them. Surgery was performed on 1.6% of the patients. The presence of an initial specific diagnosis and proximity to a university hospital significantly increased utilization rate and reduced the delays. CONCLUSION: Health services utilization for back pain in Quebec was equal or lower to what currently is practiced elsewhere, but access to specialists was not meeting the current recommendations. This would represent a 12% net increase in new specialist contacts and a quicker access in 39% who saw a specialist. Before such an effort can be considered, health care planners will need a better definition of the role of the specialist consultation in the guidelines and scientific evidence specifically addressing their benefit in primary care, especially in the absence of a specific diagnosis.

Adolescent↗
PubMed1996

Genes that control longevity in Podospora anserina.

Two genetic methods were used to estimate the number of genes that potentially modulate longevity in the filamentous fungus Podospora anserina. First, life span of strains carrying mutations selected on criteria unrelated to senescence was measured. Second, strains bearing random mutations were generated by insertional mutagenesis. Life span of these strains was then measured. Surprisingly, both methods lead to the conclusion that a large number of genes (between 600 and 3000) can modulate life span. Among, the mutations that affect longevity, 50% increase life span and 50% diminish it.

Ascomycota↗
PubMed1996

Activation of plasma membrane voltage-dependent calcium-permeable channels by disruption of microtubules in carrot cells.

Plasma membrane-bound voltage-dependent calcium channels may couple the perception of an initial stimulus to a regulated pathway for calcium influx. The activities of these channels have been shown to be very low and highly unstable but may be recruited by large-predepolarizing pulses, according to a process referred to as recruitment. By combining pharmacological and electrophysiological approaches, we demonstrate in the present paper that the cytoskeleton plays an important role in the regulation of the activity and stability of voltage-dependent calcium channels during whole-cell patch-clamp experiments on carrot protoplasts. Whereas drugs affecting the organization of the microfilament network have no measurable effect, the manipulation of the microtubule network elicits important changes. Thus, the addition of colchicine or oryzalin, which are known to disrupt microtubule organization, leads to a 6-10-fold increase in calcium channel activities and half-life. In contrast, stabilization of the microtubules by taxol has no effect on any of these parameters. The data obtained suggest that interactions of microtubules and voltage-dependent calcium channels by either direct or indirect mechanisms inhibit channel activities and decrease their half-life. In contrast, the disruption of the network overcomes such an inhibitory effect and allows the activation of calcium channels. It is speculated that under normal physiological conditions these protein-protein interactions may work in a reversible manner and contribute to signal transduction in higher plants.

Calcium Channels↗