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M Misrahi

Publications and source records attributed to M Misrahi.

At least 55 records · Page 3Linked to original sources
PubMed1996

Additional translocation (9;12)(p13;q24.1) in newly diagnosed chronic myeloid leukemia: complete cytogenetic remission after interferon therapy.

We report the case of a patient with chronic phase CML who exhibited, in the same cells, beside the Philadelphia chromosome, an additional translocation between the other chromosome 9 and one of the chromosomes 12 [t(9;12)(p13;q24.1)]. Complete cytogenetic remission with disappearance of both karyotypic abnormalities was achieved after 18 months treatment with low dose (1.4 x 10(6) U/m2/day) recombinant alpha-interferon and has been sustained with maintenance therapy for 68+ months (actual follow-up). Clonality at diagnosis and recovery of polyclonal hematopoiesis in complete cytogenetic remission were demonstrated using the polymorphism at the human androgen receptor gene (Humara) locus on chromosome X. The role of the additional translocation in the response to low dose alpha-interferon therapy remains hypothetical.

Chromosome Banding↗
PubMed1996

Analysis of the thyrotropin receptor as a candidate gene in familial Graves' disease.

Familial clustering of Graves' disease indicates a genetic etiology. Searches for genetic factors additional to the known human leukocyte antigen (HLA) association have implicated the gene for the TSH receptor (TSHR). We analyzed the linkage and association among three recently described microsatellite markers within the TSHR introns in Graves' disease in large multiply affected Welsh and English families (223 members, 44 affected individuals). Linkage analysis under a dominant model strongly rejected the hypothesis that TSHR is linked to Graves' disease in these families (lod score = -4.53). More detailed analyses also failed to provide evidence for linkage; these included combined segregation and linkage analysis, correction for HLA-DR3 status, allowance for the levels of thyroid autoantibodies in unaffected pedigree members, consideration of a recessive model for the disease, and linkage disequilibrium between disease and marker alleles. We also considered the possibility of a genetic heterogeneity of Graves' disease and thus analyzed separately the different families with a similar result. Although these results cannot eliminate a minor role of the TSHR gene locus in the genetics of Graves' disease, they argue against it being a major genetic determinant in this pathology.

Adolescent↗
PubMed1996

Four families with loss of function mutations of the thyrotropin receptor.

We observed four families with loss of function mutations of the TSH receptor gene. One patient had a homozygous Pro162 Ala substitution. The three other were compound heterozygotes: 1) Gln324-->Stop and Asp410 Asn2), Cys41 Ser and Phe525 Leu, 3) Cys390 Trp and Trp546-->Stop. In all patients, the plasma TSH concentration was increased, whereas T3 and T4 concentrations were normal. The TSH levels were normal in the heterozygous parents. These results confirmed the recessive character of TSH receptor defects. Expression of the various mutated receptors in transfected COS-7 cells demonstrated the impairment of their function. We studied the expression of the receptors on the cell surface by immunofluorescence, their ability to bind hormone, and their capacity to activate adenylate cyclase. Some mutations allowed us to identify sites that are especially important for receptor function. The substitution Cys390 Trp abolished high affinity hormone binding. Receptor mutated at Asp410 Asn bound the hormone normally, but failed to activate adenylate cyclase. This result underscores the role of this acidic extracellular residue, close to the first transmembrane segment, in signal transmission. The Phe525 Leu substitution also markedly impaired adenylate cyclase activation, underlining the importance of the second intracellular loop in receptor signaling.

Adenylyl Cyclases↗
PubMed1996

A neomutation of the thyroid-stimulating hormone receptor in a severe neonatal hyperthyroidism.

Until recently, neonatal hyperthyroidism has been considered to be related to the transplacental passage of thyroid-stimulating Ig present in the serum of the mother. We report here the case of a newborn who presented with severe hyperthyroidism, diffuse goiter, and important ocular signs (eyelid retraction and possibly proptosis). However, the absence of thyroid pathology in the parents and the lack of antithyroid antibodies in the mother and in the patient led us to suspect a nonimmune aetiology. Direct genomic sequencing of the last exon of the TSH receptor in the patient revealed a T-->C transversion yielding to a Met453-->Thr heterozygous substitution in the second transmembrane domain of the receptor. The mutation was absent in both parents. Eukaryotic expression analysis in COS-7 cells yielded a mutated receptor that produced constitutive activation of adenylate cyclase without enhancement of phospholipase C activity.

Amino Acid Sequence↗
PubMed1995

Structure of the human luteinizing hormone-choriogonadotropin receptor gene: unusual promoter and 5' non-coding regions.

The complete organization of the human luteinizing hormone-choriogonadotropin (LH/CG) receptor (LH/CGR) gene and the structure of 1591 bp of its 5' flanking region have been determined. This gene spans over 70 kbp and contains 11 exons. The first ten exons and part of the last exon encode the extracellular domain of the receptor while the transmembrane and intracellular domains are encoded by the remaining part of the last exon. The gene encodes a 701 amino acids long preprotein, contrary to a previous report of 699 amino acids. Primer extension experiments and polymerase chain reaction (PCR) mapping allowed definition of the transcription initiation site, which is located 1085 bp upstream from the initiation codon. The 5' non-coding region is thus unusually long. The promoter region which is different from the murine LH/CG receptor promoter, contains two putative TATA boxes at positions -34 and -47 and a CAAT box consensus sequence at position -89. A consensus sequence corresponding to a cAMP responsive element is found at position -697. Seven API consensus sequences are also found in the 5' flanking region of the gene. Southern blot experiments demonstrated an informative biallelic polymorphism within the human LH/CG receptor gene locus using BglII endonuclease. The cloning of the human LH/CGR gene and the determination of the organization and structure of its 5' flanking region allow the study of its hormonal, developmental and tissue-specific regulation. Primers and PCR conditions are described for the direct genomic sequencing of all the exons of the gene. This information should facilitate the study of pathological mutations of the receptor.

Amino Acid Sequence↗
PubMed1995

[Pituitary glycoprotein hormone receptors].

Monoclonal antibodies have been raised against the porcine LH receptor and have allowed to clone the corresponding messenger RNA from testicular cells. The stricture of the LH receptor has been determined. It shows similarities but also differences with other G protein coupled receptors. Specially a large extracellular domain is specific of that new family of receptors. Variant forms of the LH receptor generated by alternative splicing and lacking transmembrane domain have been isolated. Immunochemical and immunocytochemical studies have been performed. Three different forms of the LH receptor are physiologically expressed: a mature 85kDa transmembrane species, a 68 kDa high mannose containing species corresponding to a precursor which accumulates inside the cells, and truncated 45-48kDa molecular weight species corresponding to the variant messenger RNAs identified during the cloning of the receptor. A novel zonation of the ovary has been described by immunocytochemical studies. Cross hybridization with the LH receptor clone allowed to isolate the related TSH receptor from human thyroid tissue. The human LH and FSH receptor genes have been localized to chromosome 2p21 and the TSH receptor gene to chromosome 14q31. The genes are very large (> 60 kbp) and have introns only within the 5' part encoding the extracellular domain of the receptor. Immunoelectron microscopic studies performed in Leydig cells and in stably transfected L cells have allowed to study intracellular traffic of the LH receptor. The same approach was used to study the transendothelial transfer of hCG in testicular microvasculature.

Animals↗
PubMed1995

Abnormal chromatin clumping in granulocytes in a case of Ph1-negative, BCR-ABL rearrangement positive, haematologically atypical chronic myeloid leukaemia (CML).

In the present study, we report the case of a patient displaying an abnormal chromatin clumping (ACC) syndrome, a rare disease which shares features with both myeloproliferative and myelodysplastic disorders. Although various non specific cytogenetic abnormalities have been observed in ACC, the presence of a Ph1 chromosome has not been reported. In our patient, despite a lack of Ph1, PCR analysis of blood and bone marrow samples revealed a BCR-ABL rearrangement. These results indicate that at least some cases of ACC syndrome could represent a form of Ph1-negative chronic myeloid leukaemia.

Aged↗
PubMed1994

Processing of the precursors of the human thyroid-stimulating hormone receptor in various eukaryotic cells (human thyrocytes, transfected L cells and baculovirus-infected insect cells).

The complementary DNA for human thyroid-stimulating hormone (TSH) receptor encodes a single protein with a deduced molecular mass of 84.5 kDa. This protein is cleaved during its maturation in the human thyroid since the receptor protein has been shown to be composed of two subunits (alpha subunit of approximately 53 kDa and beta subunit of approximately 38 kDa) held together by disulfide bridges [Loosfelt, H., Pichon, C., Jolivet, A., Misrahi, M., Caillou, B., Jamous, M., Vannier, B. & Miligrom, E. (1992) Proc. Natl Acad. Sci. USA 89, 3765-3769]. A similar processing occurs in an L cell line permanently expressing the human TSH receptor. The processing is however incomplete, resulting in a permanent accumulation of a 95-kDa high-mannose precursor which is present only in trace amounts in the thyroid. Pulse-chase experiments show the successive appearance in the L cells of two precursors: initially the approximately 95-kDa high-mannose glycoprotein followed by a approximately 120-kDa species containing mature oligosaccharides. This latter precursor is then processed into the alpha and beta subunits. In primary cultures of human thyrocytes precursors of similar size are detected. Spodoptera frugiperda insect cells (Sf9 and Sf21) infected with a recombinant baculovirus encoding the human TSH receptor synthesize a monomeric protein of about 90 kDa soluble only in denaturing conditions. Comparison with the product of in vitro transcription-translation experiments (approximately 80 kDa), suggests that it may be incompletely or improperly glycosylated. The TSH receptor expressed in these cells is unable to bind the hormone. Immunoelectron microscopy studies show that in human thyrocytes most of the receptor is present on the cell surface; in L cells the receptor is detected on the cell surface, as well as in the endoplasmic reticulum and in the Golgi apparatus (this intracellular pool of receptor molecules probably corresponding to the high-mannose precursor); in insect cells nearly all the receptor molecules are trapped in the endoplasmic reticulum. These differences in receptor distribution are concordant with the differences observed for receptor processing.

Animals↗
PubMed1994

The progesterone receptor. Biological effects of progestins and antiprogestins.

The progesterone receptor displays the typical three-domains structure of the steroid-thyroid receptor family. The central domain contains two 'zinc finger' structures responsible for the specific recognition of the cognate DNA sequences. The carboxy-terminal domain contains the hormone and anti-hormone binding site. Progesterone and synthetic progestins (R5020, Org 2058) activate the receptor, provoke its phosphorylation and DNA-binding ability and induce its regulatory activities. The antagonist RU38486 elicits the same sequence of events but leads to an abortive conclusion without specific gene transactivation. The progesterone receptor is down-regulated by its own ligand at the transcriptional level through inhibition of oestrogen receptor-mediated induction through protein-protein interactions. This mechanism is also inhibited by RU38486.

Animals↗
PubMed1994

[LH receptors. A new family of G-protein receptors].

Monoclonal antibodies have been raised against porcine LH receptor and allowed to clone the corresponding messenger RNA from testicular cells. The structure of the LH receptor have been determined. It shows similarities but also differences to other G protein coupled receptors. In particular a large extracellular domain is specific for that family of receptors. Variants forms of the LH receptor generated by alternative splicing and lacking transmembrane domains have been isolated. Immunochemical and immunocytochemical studies have been performed. Three different forms of the LH receptor are physiologically expressed: a mature 85 kDa transmembrane species, a 68 kDa high mannose containing species corresponding to a precursor which accumulate inside the cells, and truncated 45-48 kDa molecular weight species corresponding to the variant messenger RNAs identified during the cloning of the receptor. A novel zonation of the ovary has been described by immunocytochemical studies. Cross hybridisation with the LH receptor clone allowed to isolate the related human TSH receptor from thyroïds. The human LH and FSH receptor genes have been localized to chromosome 2p21 and the TSH receptor gene to chromosome 14q31. The genes are very large and have introns only within their 5' part corresponding to the extracellular domain of the receptor.

Cloning, Molecular↗
PubMed1993

Structure of the human progesterone receptor gene.

The complete organization of the human progesterone receptor (hPR) gene has been determined. It spans over 90 kbp and contains eight exons. The first exon encodes the N-terminal part of the receptor. The DNA binding domain is encoded by two exons, each exon corresponding to one zinc finger. The steroid binding domain is encoded by five exons. The nucleotide sequence of 1144 bp of the 5' flanking region has been determined.

Amino Acid Sequence↗
PubMed1992

Variant forms of the pig lutropin/choriogonadotropin receptor.

The cloning and sequencing of porcine lutropin/choriogonadotropin (LH/hCG) receptor messenger RNAs have shown the presence of a full-length receptor (pLHR-A) and of shorter variants lacking either the transmembrane and the intracellular domains (pLHR-B and pLHR-C) or only the transmembrane domain (pLHR-D). Moreover, immunoblotting of testicular membrane extracts has detected 85-, 68-, and 45-48-kDa proteins reacting with antireceptor antibodies. Transfection experiments were performed to assign the protein species to the various messenger RNAs and to study the function of the various receptor species. COS-7 and L-cells transfected with an expression vector encoding full-length receptor pLHR-A yielded a protein of apparent molecular mass of 105 kDa. This corresponded to the complete receptor which had undergone a different glycosylation pattern to that found in testis, since after digestion with peptide N-glycosidase F both the 105-kDa COS-7 protein and the 85-kDa testicular glycoprotein yielded a holoprotein of approximately 63 kDa. Transfection with pLHR-A also yielded a high proportion of the 68-kDa glycoprotein which was shown by digestion with endoglycosidase H to be a high-mannose precursor of the full-length receptor. The existence of a large pool of precursor species in both transfected cells and Leydig cells evokes possible physiological regulations at the level of receptor maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Two-subunit structure of the human thyrotropin receptor.

The extracellular and intracellular domains of the human thyrotropin receptor were expressed in Escherichia coli and the proteins were used to produce monoclonal anti-receptor antibodies. Immunoblot studies and immunoaffinity purification showed that the receptor is composed of two subunits linked by disulfide bridges and probably derived by proteolytic cleavage of a single 90-kDa precursor. The extracellular alpha subunit (hormone binding) had an apparent molecular mass of 53 kDa (35 kDa after deglycosylation with N-glycosidase F). The membrane-spanning beta subunit seemed heterogeneous and had an apparent molecular mass of 33-42 kDa. Human thyroid membranes contained a 2.5- to 3-fold excess of beta subunits over alpha subunits. Immunocytochemistry showed the presence of both subunits in all the follicular thyroid cells, and both subunits were restricted to the basolateral region of the cell membrane.

Amino Acid Sequence↗
PubMed1992

[LH and TSH receptors. A new family of G protein-coupled receptors].

Monoclonal antibodies have been raised against porcine LH receptor and allowed to clone the corresponding messenger RNA from testicular cells. Cross hybridisation with the LH receptor clone allowed to isolate a clone corresponding to the human TSH receptor from thyroids. The structure of both receptors have been determined. They show similarities but also differences to other G protein coupled receptors. In particular a large extracellular domain is specific of that new family of receptors. Variant forms of the LH receptor lacking transmembrane domains have been isolated. The obtention of monoclonal antibodies against both receptors allowed immunochemical and immunocytochemical studies to be performed. The human LH receptor gene have been localized to chromosome 2p21 and TSH receptor gene to chromosome 14q31. The complete organisation of the human TSH receptor gene has been determined.

Animals↗
PubMed1991

Composite structure of the human thyrotropin receptor gene.

The exon/intron organization and the structure of the 5' flanking region of the human thyrotropin receptor gene (hTSH-R) were determined. The hTSH-R gene spans more than 60 kb and is split into ten exons. The extracellular domain is encoded by the first nine exons and part of the last exon, whereas the transmembrane and intracellular domains are encoded in totality by the last exon. The leucine-rich repeats of the extracellular domain are encoded as monomers or multimers by separate exons. The TSH receptor gene seems to have arisen by insertion of a DNA sequence encoding repeated leucine-rich elements between the regions encoding the extracellular and the transmembrane domains of a proto-receptor gene ressembling the intronless beta adrenergic receptor genes. Primer extension and S1 mapping experiments identified three transcription start sites. In the hTSH-R gene, the main site was located 157 bp upstream from the start of translation. The promoter region is very GC-rich and contains multiple SP1, ETF and AP2 binding site consensus sequences.

Amino Acid Sequence↗
PubMed1991

Characterization of the hormone responsive element involved in the regulation of the progesterone receptor gene.

The transcription of the progesterone receptor gene is induced by estrogens and decreased by progestins. Studies were performed to define the regions of the gene and the molecular mechanisms involved. No hormonal regulation could be observed using 5' flanking regions of the gene up to -2762 in front of a heterologous gene. Estrogen and progestin regulation could be observed only when using fragments of the gene extending down to +788. Progressive deletions from the 5' and 3' ends, site-directed mutagenesis and DNase protection experiments with purified estrogen receptor suggested that the biologically active estrogen responsive element (ERE) is present at +698/+723, overlapping the initiation of translation. An oligonucleotide was synthesized bearing this ERE and shown to impart estrogen inducibility to a heterologous gene. Its regulation by anti-estrogens corresponded to that of the in situ progesterone receptor gene since tamoxifen was a partial agonist whereas ICI 164384 was a full antagonist. This ERE also mediated down-regulation by progestins in the presence of the progesterone receptor, even though it has no progesterone receptor binding ability. DNase footprinting showed that this effect was not due to a decrease of estrogen receptor affinity for the ERE in the presence of progesterone receptor. Finally, use of deletion mutants of the progesterone receptor showed that the steroid binding and the DNA binding domains were necessary for down-regulation whereas deletions of various parts of the N-terminal domain were without effect.

Animals↗