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J Pelletier

Publications and source records attributed to J Pelletier.

At least 55 records · Page 3Linked to original sources
PubMed2000

NAP-2: histone chaperone function and phosphorylation state through the cell cycle.

We have recently cloned the human nucleosome assembly protein 2 (NAP-2). Here, we demonstrate that casein kinase 2 (CKII) from HeLa cell nuclear extracts interacts with immobilized NAP-II, and phosphorylates both NAP-2 and nucleosome assembly protein 1 (NAP-1) in vitro. Furthermore, NAP-1 and NAP-2 phosphorylation in crude HeLa cell extracts is abolished by heparin, a specific inhibitor of CKII. Addition of core histones can stimulate phosphorylation of NAP-1 and NAP-2 by CKII. NAP-2 is also a phosphoprotein in vivo. The protein is phosphorylated at the G0/G1 boundary but it is not phosphorylated in S-phase. Here, we show that NAP-2 is a histone chaperone throughout the cell cycle and that its cell-cycle distribution might be governed by its phosphorylation status. Phosphorylated NAP-2 remains in the cytoplasm in a complex with histones during the G0/G1 transition, whereas its dephosphorylation triggers its transport into the nucleus, at the G1/S-boundary, with the histone cargo, suggesting that binding to histones does not depend on phosphorylation status. Finally, indirect immunofluorescence shows that NAP-2 is present during metaphase of HeLa and COS cells, and its localization is distinct from metaphase chromosomes.

Animals↗
PubMed2000

Identification and characterization of MTR1, a novel gene with homology to melastatin (MLSN1) and the trp gene family located in the BWS-WT2 critical region on chromosome 11p15.5 and showing allele-specific expression.

Alterations within human chromosomal region 11p15.5 are associated with the Beckwith-Wiedemann syndrome (BWS) and predisposition to a variety of neoplasias, including Wilms' tumors (WTs), rhabdoid tumors and rhabdomyosarcomas. To identify candidate genes for 11p15. 5-related diseases we compared human genomic sequence with expressed sequence tag and protein databases from different organisms to discover evolutionarily conserved sequences. Herein we describe the identification and characterization of a novel human transcript related to a putative Caenorhabditis elegans protein and the trp (transient receptor potential) gene. The highest homologies are observed with the human TRPC7 and with melastatin 1 ( MLSN1 ), whose transcript is downregulated in metastatic melanomas. Other genes related to and interacting with the trp family include the Grc gene, which codes for a growth factor-regulated channel protein, and PKD1/PKD2, involved in polycystic kidney disease. The novel gene presented here (named MTR1 for MLSN1 - and TRP -related gene 1) resides between TSSC4 and KvLQT1. MTR1 is expressed as a 4.5 kb transcript in a variety of fetal and adult tissues. The putative open reading frame is encoded in 24 exons, one of which is alternatively spliced leading to two possible proteins of 872 or 1165 amino acids with several predicted membrane-spanning domains in both versions. MTR1 transcripts are present in a large proportion of WTs and rhabdomyosarcomas. RT-PCR analysis of somatic cell hybrids harboring a single human chromosome 11 demonstrated exclusive expression of MTR1 in cell lines carrying a paternal chromosome 11, indicating allele-specific inactivation of the maternal copy by genomic imprinting.

Adult↗
PubMed2000

Different transcriptional properties of mSim-1 and mSim-2.

The mSim-1 and mSim-2 gene products are mammalian homologues of the Drosophila Sim gene. The dSim gene product transactivates through a DNA binding site known as the CNS midline enhancer (CME) element. We have investigated the transcriptional properties of mSIM-1 and mSIM-2 mediated through the CME element in concert with their dimerization partners, ARNT and ARNT-2. The mSIM-1/ARNT heterodimer transactivates reporter constructs via the ARNT carboxy-terminus. However, mSIM-2 quenches ARNT transactivation. We find that mSIM-2 competes with mSIM-1 for binding to ARNT, suggesting a possible antagonism between these transcription factors.

Animals↗
PubMed2000

["Multiple sclerosis plus": leukoencephalopathies at the frontiers of internal medicine].

INTRODUCTION: Multiple sclerosis (MS) is an inflammatory, demyelinating and probably autoimmune disease affecting the white matter of the central nervous system (CNS). Due to the absence of specific clinical and laboratory markers, diagnosis remains difficult. CURRENT KNOWLEDGE AND KEY POINTS: In particular, no clinical or paraclinical investigation is satisfactory to distinguish definite MS from other autoimmune or inflammatory diseases, especially when they predominantly affect the CNS. Moreover, previous studies have reported that patients with definite MS could present clinical systemic signs suggestive of other inflammatory or autoimmune diseases, and that MS could be associated with other autoimmune diseases. On the other hand, the presence of biological autoimmune abnormalities, including antinuclear antibodies and antiphospholipid antibodies, has been observed, with a high frequency in patients with MS in comparison to control populations. These clinical and laboratory features could therefore represent a new nosological entity characterized by a systemic immune dysregulation more extensive than the CSN target, or a distinct subgroup of MS patients with a classical course of the disease. Because of the impact of the new therapeutic approach to MS, an important issue concerning this aspect that should be addressed is the use of immunomodulatory therapy, especially with interferon beta. It appears necessary to consider these abnormalities before treating MS patients with preventive therapy, in particular in the perspective of new strategies, such as treatment at an early stage of the disease or combination therapies.

Behcet Syndrome↗
PubMed2000

Association between expression of reproductive seasonality and alleles of the gene for Mel(1a) receptor in the ewe.

To determine whether a link exists between reproductive seasonality and the structure of the gene for melatonin receptor Mel(1a), the latter was studied in two groups of Mérinos d'Arles (MA) ewes previously chosen for their genetic value, which took into account their own out-of-season ovulatory activity adjusted by environmental parameters and that of their relatives. The genomic DNA of 36 ewes found regularly cycling in spring (group H) and that of 35 ewes never cycling in spring (group L) during the 2-3 yr before the present study was prepared, and the cDNA corresponding to almost all exon II was amplified and checked for the presence of MnlI restriction sites. The presence (+) or absence (-) of an MnlI site at position 605 led to genotypes "++", "+-", and "--", whose frequencies differed significantly (P < 0.001) between the H and L groups: 52.8%, 47.2%, and 0% vs. 28.5%, 42.9%, and 28.5%, respectively. Sequencing of exon II cDNA in group L ewes with genotype -- showed the presence of only one allele - with 4 mutations, while that in ewes with genotype ++ showed different types of alleles unrelated to the H or L groups. These + alleles exhibited a combination of 1 to 7 of the 8 mutations recorded in the part of exon II studied. The genotyping of 29 ewes from the more seasonal Ile-de-France breed indicated that 38% of animals had a -- genotype and exhibited the same mutations as in the MA ewes. Finally, a comparison of (125)I-melatonin binding to membrane preparations of pars tuberalis showed a lower number of binding sites (P < 0. 0005) in MA ewes with genotype ++ than in those with genotype -- (43. 2 +/- 4.4 vs. 75.4 +/- 8.4 fmol/mg protein in genotype ++ and genotype --, respectively). In conclusion, the data show an association between genotype -- for site MnlI at position 605 and seasonal anovulatory activity in MA ewes.

Alleles↗
PubMed2000

[Cognitive and emotional disorders in multiple sclerosis. Can a management strategy be envisioned?].

There is a lack of precise data concerning the natural history of cognitive disorders in multiple sclerosis (MS), but recent neuropsychological studies have demonstrated that the incidence of such disorders in MS appears to be frequent (40-65% of cases), and have shown in particular that recent memory, conceptual reasoning, attention, executive functions, visuospatial perception and information processing speed are negatively affected. In contrast, language functions, general intelligence and implicit memory appear to be relatively well preserved. Although the presence and the degree of cognitive disorders does not seem to be directly linked to disease duration or to the extent of physical disability, the relationship between cognitive decline and brain lesions detected by magnetic resonance imaging (MRI) is still a subject of discussion. The prevalence of emotional and affective disorders is difficult to estimate. Their frequency has only rarely been investigated, and the lack of data on the natural history of these disorders and those factors which they have in common (the psychosocial consequences of this chronic and disabling disease, cognitive impairment, and brain lesions) further complicate the determination of treatment strategy. The adoption of appropriate strategies could limit the negative impact of this disease on the social functioning of MS patients.

Cognition Disorders↗
PubMed2000

[Sensitized immunofixation: a new technique for analyzing the oligoclonal pattern of CSF immunoglobulins].

Intrathecal immunoglobulin synthesis is observed in more than 90% of all cases of multiple sclerosis, producing a specific CSF IgG oligoclonal electrophoretic pattern. The consensual method used as reference is isoelectric focusing (IEF). We developed a new CSF Ig analysis method by immunofixation (IF). The method includes an immunoenzymatic detection step performed directly on the gel allowing the use of unconcentrated CSF and avoiding the blotting step. The reliability of this method was established by the analysis of 210 CSF/serum pairs including defined, probable and possible MS, other inflammatory CNS diseases and controls (noninflammatory CNS diseases and peripheral nervous system diseases). Intrathecal IgG synthesis was detected in 95.5% of defined MS cases. The specificity for CNS inflammatory diseases including MS diagnosis, evaluated by comparison with controls, was 98.8%. This new method is quicker and visual interpretation is easier than with IEF. It is a semi-automated method that should be considered for standardization of CSF IgG analysis.

Adult↗
PubMed1999

Modification of EWS/WT1 functional properties by phosphorylation.

In many human cancers, tumor-specific chromosomal rearrangements are known to create chimeric products with the ability to transform cells. The EWS/WT1 protein is such a fusion product, resulting from a t(11;22) chromosomal translocation in desmoplastic small round cell tumors, where 265 aa from the EWS amino terminus are fused to the DNA binding domain of the WT1 tumor suppressor gene. Herein, we find that EWS/WT1 is phosphorylated in vivo on serine and tyrosine residues and that this affects DNA binding and homodimerization. We also show that EWS/WT1 can interact with, and is a substrate for, modification on tyrosine residues by c-Abl. Tyrosine phosphorylation of EWS/WT1 by c-Abl negatively regulates its DNA binding properties. These results indicate that the biological activity of EWS/WT1 is closely linked to its phosphorylation status.

Animals↗
PubMed1999

Molecular genetics of chromosome translocations involving EWS and related family members.

Many types of sarcomas are characterized by specific chromosomal translocations that appear to result in the production of novel, tumor-specific chimeric transcription factors. Many of these show striking similarities: the emerging picture is that the amino-terminal domain of the fusion product is donated by the Ewing's sarcoma gene (EWS) or a related member from the same gene family, whereas the carboxy-terminal domain often consists of a DNA-binding domain derived from one of a number of transcription factors. Given the observation that the different translocation partners of the EWS protooncogene are associated with distinct types of sarcomas, the functional consequence of fusing EWS (or a related family member) to a different DNA-binding domain can only be understood in the context of functional studies that define the specificity of action of the different fusion products. An understanding of the molecular structure and function of these translocations provides new methods for diagnosis and novel targets for therapeutics.

DNA-Binding Proteins↗
PubMed1999

The Wilms' tumor suppressor gene (wt1) product represses different functional classes of transcriptional activation domains.

We have studied the ability of the wt1 tumor suppressor gene product to repress different classes of activation domains previously shown to stimulate the initiation and elongation steps of RNA polymerase II transcription in vivo. Repression assays revealed that WT1 represses all three classes of activation domains: Sp1 and CTF, which stimulate initiation (type I), human immunodeficiency virus type I Tat fused to a DNA-binding domain, which stimulates predominantly elongation (type IIA), and VP16, p53 and E2F1, which stimulate both initiation and elongation (type IIB). WT1 is capable of exerting its repression effect over a significant distance when positioned approximately 1700 bp from the core promoter. Deletion analysis of WT1 indicates that the responsible domain resides within the first 180 N-terminal amino acids of the protein. Nuclear run-ons analyzing the effects of WT1 on initiation of transcription demonstrate inhibition of this process. Our observations imply that WT1 can repress activators that stimulate initiation and/or elongation.

Animals↗
PubMed1999

Development of a database management/analysis system for field research activities within a coordinated research project.

There are several ways a database/analysis system can assist a scientist engaged in field research. Specifically, it can assist the scientist with accurate data collection and more rigorous data analyses. The database management portion of this system allows accurate data collection and provides easy data entry through the use of forms. In addition, it can provide the scientist with structured methods of error checking data entry and checking for implausible values and false zeros. The system can also assist the scientist with the organization of the data and provide easy methods of sorting, grouping, and selecting data for analysis. Data can then be exported to a data analysis program where the first step is data validation. A menu of analyses using examples from the coordinated research project (CRP) are demonstrated using statistical methods that test continuous and categorical data.

Analysis of Variance↗
PubMed1999

Toxicity and phototoxicity of mixtures of highly lipophilic PAH compounds in marine sediment: can the SigmaPAH model Be extrapolated?

The additivity of toxic units was tested using sediments contaminated with mixtures of highly lipophilic (log Kow > 4.5) parent and alkylated PAHs. The direct toxicity and photoinduced toxicity of these mixtures were examined in standard 10-day sediment toxicity tests using the infaunal amphipod Rhepoxinius abronius, with mortality and the survivors' ability to rebury as endpoints. Survivors of the initial 10-day tests were then exposed for 1 h to ultraviolet (UV) radiation and the results compared to initial (10-day) endpoints. Tissue residues and lipids were measured and biota-sediment accumulation factor (BSAF) values determined. The results indicated that the bioaccumulated contaminants were not initially toxic, however, they were highly phototoxic. Although the summed toxic units of these contaminants appeared to be nonadditive, additivity was not disproved as inaccuracies in extrapolating the Kow-LC50 QSAR or insufficient exposure duration might also have accounted for the observed results. Critical body residue (CBR) estimates for R. abronius were similar while BSAF values were much larger (10x) in comparison to other studies, which used amphipods and PAHs. The phototoxicity of mixtures of contaminants were similar to the phototoxicity of single contaminants when expressed on a molar basis, which suggests that phototoxicities may be roughly additive.

Journal Article↗
PubMed1999

Isolation and characterization of AtMLH1, a MutL homologue from Arabidopsis thaliana.

DNA mismatch repair systems play an essential role in the maintenance of genetic information in living organisms and are also implicated in genetic recombination and genome stability. Using degenerate primers, we have cloned the first plant homologue of the E. coli MutL gene, which we have called AtMLH1 for Arabidopsis thaliana MutL-homologue 1. AtMLH1 is present as a single-copy gene in the Arabidopsis genome and is located on the top arm of chromosome 4. Sequence analysis revealed that the product of this gene shows extensive sequence homology with other eukaryotic MLH1 proteins. As mlh1-deficient lines would be useful for studying the biological function of this gene, several populations that had been mutagenized using T-DNA and transposon insertions were screened to identify such mutants. One line that carries a T-DNA insertion in the promoter region of the AtMLH1 gene was isolated. Surprisingly, although the insertion occurred only approximately 80 bp upstream of the putative transcription start site, Northern analyses revealed very low but similar amounts of AtMLH1 transcript in both the wild type and the T-DNA insertion lines. RT-PCR analyses suggest, however, that transcription is initiated further upstream in the insertion line and that the T-DNA may supply this novel initiation site. Finally, no increase in microsatellite instability - a phenotype often associated with mutations in mismatch repair genes - was observed in plants homozygous for this insertion.

Adenosine Triphosphatases↗
PubMed1999

Sheep 5HT2A receptors: partial cloning of the coding sequence and mRNA localization by in situ hybridization in the ewe hypothalamus.

UNLABELLED: Serotonin and serotonin receptors of class II (5HT2-R) are thought to be involved in the neural mechanisms which regulate the LH release associated with photoperiodic changes in sheep. A specific premammillary hypothalamic area displaying a significant binding of 3H-ketanserin, a potent 5HT2-R antagonist, was previously identified. The aim of the present study was to ascertain by in situ hybridization (ISH) that 5HT2-R mRNA-containing cells were also present in this specific hypothalamic area. Total RNA was prepared from sheep pars tuberalis/median eminence, and a cDNA fragment of 546 bp was amplified by reverse transcriptase polymerase chain reaction (RT-PCR) using degenerated primers deduced from the human and rat 5HT2A-R sequences. After cloning and sequencing, the sheep nucleotide sequence had the highest homology (85.1-92.3%) with the other known mammalian 5HT2-R or 5HT2A-R sequences. Homology with other 5HT-R subtypes or other monoamine receptors was much lower, 60% at maximum. After ISH using sense and antisense 35S-riboprobes, specific labelling was found in different parts of the hypothalamus, especially in the mammillary bodies where the binding was higher. Within the hypothalamus, the density of labelled cells, mainly neurons, varied considerably. It was maximal in the mammillary bodies and also in a restricted ventral region of the premammillary hypothalamus located from about 500/700 micrometer to 1200/1400 micrometer in front of the mammillary recess, where 3H-ketanserin binding was previously reported. IN CONCLUSION: (1) the structural study of the sequence indicated that the new cloned cDNA corresponds to the sheep 5HT2-R class and, probably, to the 5HT2A-R subtype and (2) the ISH studies revealed that a restricted area of the premammillary hypothalamus shows a large number of 5HT2-R mRNA-containing neurons.

Animals↗
PubMed1999

An open study of tinea capitis in 50 children treated with a 2-week course of oral terbinafine.

BACKGROUND: Terbinafine is used in the treatment of dermatophyte infections. There have been several studies suggesting a good response to terbinafine in treating tinea capitis, specifically with dermatophytes of the Trichophyton species. METHODS: We enrolled 50 consecutive children with a clinical diagnosis of tinea capitis into an open study using terbinafine for 2 weeks. RESULTS: Clinical and mycologic cure occurred in more than 86% of patients with no side effects and good compliance. CONCLUSION: In this study terbinafine was a safe and effective treatment of tinea capitis in children, particularly when caused by the Trichophyton species.

Adolescent↗
PubMed1999

Suppression of tumor necrosis factor (TNF-alpha) gene expression by prostaglandin E(2). Role Of early growth response protein-1 (Egr-1).

We examined the mechanism by which PGE(2)suppresses the expression of TNF-alpha in human macrophages and synovial fibroblasts. Prostaglandin E(2)increased, in a time and dose-dependent (EC(50)75+/-15ng/ml, mean+/-SD) fashion, the expression and synthesis of Egr-1/Krox24 as judged by Northern blotting and electrophoretic mobility gel-shift analysis, respectively. In human macrophagic THP-1 cells, rhIL-17 increased promoter activity by 7. 6+/-0.35-fold over controls, an effect that was abrogated in a dose-dependent fashion by coincubations with PGE(2)(IC(50)25+/-4ng/ml). An intact Egr-1/Krox-24 enhancer sequence in the TNF-alpha promoter region was essential for the latter PGE(2)-dependent inhibitory effect as double base substitutions (GC-->TT) in the sequence curtailed promoter response to PGE(2). Overexpression of two dominant negative Egr-1/Krox-24 constructs in THP-1 cells considerably diminished the inhibitory effects of PGE(2)on rhIL-17-induced TNF-alpha mRNA expression. We conclude that PGE(2)inhibits induced TNF-alpha expression in target cells through an Egr-1/Krox-24 mediated signaling process.

Blotting, Northern↗