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A Jolivet

Publications and source records attributed to A Jolivet.

At least 37 records · Page 2Linked to original sources
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

Unmasking of an immunoreactive site on the alpha subunit of human choriogonadotropin bound to the extracellular domain of its receptor.

To define the human choriogonadotropin (hCG) hormone's contact points with its receptor, we examined five monoclonal anti-hCG antibodies for their binding ability to the hCG-intact receptor complex and to the hCG-truncated extracellular N-terminal half receptor complex. hCG-producing CHO cells were transfected with the N-terminal 297 residues of the porcine LH/CG receptor and the secreted complexes were detected by two-site immunoassays based on anti-receptor and anti-hCG antibodies. Four antibodies did not show any differences toward the two types of complexes. In contrast, a particular antibody, directed to the alpha-subunit of hCG, recognized the hCG-truncated receptor complex but not the hCG-intact receptor complex. These results substantiate recent reports indicating that, if most of the whole alpha/beta dimer is bound to the N-terminal half of the receptor, some regions of the alpha-subunit might be contacting the C-terminal half.

Animals↗
PubMed1993

Immunocytochemical localization of progesterone receptors in galanin neurons in the guinea pig hypothalamus.

A double-label immunocytochemical technique was used to determine whether progesterone receptor-containing neurons in the female guinea-pig hypothalamus also contained galanin. Adult ovariectomized guinea-pigs were primed by estradiol to induce progesterone receptors and injected intracerebroventricularly with colchicine to visualize galanin-immunopositive neurons. A small proportion of progesterone receptor-containing perikarya in the medial preoptic area and the mediobasal hypothalamus were bound to be immunoreactive for galanin. The medial preoptic, periventricular and arcuate nuclei showed the greatest concentration of double-labelled cells. Galanin varicosities appeared in close proximity to neurons with progesterone receptor-containing nuclei. These results provide neuroanatomical evidence that a subset of hypothalamic galanin-immunoreactive neurons is directly regulated by progesterone.

Animals↗
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

New functional zonation in the ovary as shown by immunohistochemistry of luteinizing hormone receptor.

Monoclonal anti-LH receptor antibodies were used to study receptor distribution in the various structures of porcine ovary. Primordial and primary follicles were not labeled. Immunoreactivity appeared on the thecal cells of secondary follicles of approximately 100-200 microns in diameter. In large antral follicles and preovulatory follicles granulosa cells were also labeled, whereas two zones were observed in the theca interna. The region close to the lamina basalis (approximately 1/3 of the thecal cells) appeared devoid of LH receptors, whereas a strong labeling was observed on the most external region. Thecal cells were also labeled in atretic follicles. There was no labeling of the oocyte. In cyclic corpora lutea only the most external cells, probably of thecal origin, were stained. The most abundant cells, of granulosa origin, were not labeled. In the interstitium few cells were immunolabeled; they proceeded either from remnants of atretic follicles or existed as groups of isolated cells. Thus both the theca interna of preovulatory follicles and the corpus luteum are heterogenous structures composed of two zones of which only one is directly responsive to LH. No LH immunoactivity could be detected in nontarget organs (liver, lung, thyroid gland, small intestine, fallopian tube, and uterus).

Animals↗
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↗
PubMed1990

Monoclonal antibodies against native ant denatured forms of estrogen-induced breast cancer protein (BCEI/pS2) obtained by expression in Escherichia coli.

Several vectors were used to express the complementary DNA for breast cancer estrogen-induced protein BCEI (also called pS2) in Escherichia coli. The best results were obtained by using the pUR 290 expression vector after deletion of the sequence encoding the signal peptide of the protein. In these conditions, beta-galactosidase-BCEI/pS2 fusion protein accounted for approximately 20% of total proteins in bacterial extracts. It was purified by chromatography on DEAE-Trisacryl or by gel electrophoresis and electroelution. Polyclonal antibodies were obtained by immunization of rabbits and goats, and monoclonal antibodies were raised in mice. Two types of monoclonal antibodies were obtained: one class recognized the native protein and was very efficient for the immunoprecipitation and immunopurification of the protein from breast cancer cells; a second class recognized the denatured protein and was especially effective for immunoblot studies. BCEI/pS2 could be detected by immunocytochemistry in breast cancer biopsies using monoclonal antibodies on frozen or paraffin-embedded sections. One of the antibodies (mBCEI11) exhibited high affinity for the protein and could be used at 1.9 micrograms/ml concentration for immunolabeling of histological sections. The mBCEI11 antibody was used in immunoaffinity chromatography to purify the peptide in a single step from culture media of estrogen-treated MCF-7 cells.

Antibodies↗
PubMed1990

A small subpopulation of progesterone receptor-containing neurons in the guinea pig arcuate nucleus projects to the median eminence.

In female guinea pigs, a combination of retrograde tracing and immunofluorescence for progesterone receptors (PR) was applied to determine if PR-immunoreactive (PR-IR) neurons in the arcuate nucleus (AR) send their axons directly to the median eminence (ME). Axonal projections to the ME were studied by different techniques using fluorescent dyes. From 31 adult animals, ovariectomized and primed by estradiol, small deposits of Lucifer Yellow (LY) were made on the cut surface of the ME, either by direct application of LY crystals or by iontophoresis. These techniques were carried out on excised mediobasal hypothalamus maintained in vitro and allowed visualization of AR perikarya projecting to the ME after dye diffusion in the severed axons. In another group of ten immature animals primed by estradiol, Granular Blue (GB) was injected in the jugular vein. Blood-borne GB was taken up in the ME by intact nerve endings and retrogradely transported to the perikarya of origin. PR-IR neurons and perikarya filled with LY or retrogradely labeled by GB were intermingled with each other throughout the rostrocaudal extent of the AR. Double-labeled cells, displaying PR immunoreactivity and dye labeling, were observed consistently, but their number was small. This result demonstrates that some AR neurons sending axonal projections to the ME are target cells for progesterone. As the majority of PR-IR neurons in the AR do not project to the ME, it is suggested that most PR-IR neurons present in this nucleus form local circuit projections or project to distant areas of the central nervous system.

Animals↗
PubMed1990

Monoclonal antibodies for immunocytochemistry of progesterone receptors (PR) in various laboratory rodents, livestock, humans, and chickens: identification of two epitopes conserved in PR of all these species.

Over 90 mouse monoclonal antibodies have been raised against rabbit and human uterine progesterone receptor (PR). These antibodies, because of their specificity, are powerful tools with which to examine the localization, structure, and function of PR. A selection of 22 well characterized mABs was made to test their ability to give the best immunocytochemical staining of PR in various species. Comparative analysis of the antibodies led to the following conclusions. Li 417 (and, to a lesser extent, Let 126) was the best monoclonal in humans; Let 126 and Mi 60 were the most sensitive monoclonals in guinea pigs, rabbits, and monkeys. In sheep, sows, cows and mares as well as in rats and chickens Let 81 or Let 548 gave the best results (Let 126 was also effective in sows and mares, while Li 169 was also effective in sheep and cows). Two antibodies (Li 169 and Let 548) cross-reacted with PR in all of the species tested, including mammals and birds, and appeared to recognize two highly conserved antigenic sites. Remarkably, these conserved sequences are located in the highly variable N-terminal part of the receptor; they may, thus, be related to the still poorly understood function of this domain of the receptor.

Animals↗
PubMed1990

Monoclonal antibodies against luteinizing hormone receptor. Immunochemical characterization of the receptor.

Human CG (hCG)-receptor complexes were solubilized from porcine testicular membranes. They were chromatographed on an immunomatrix of Affi-Gel 10-D1E8 anti beta-hCG monoclonal antibody (this antibody has been shown not to interfere with hCG binding to receptor). Elution was performed at alkaline pH, a condition in which hCG-receptor complexes are relatively stable. Immunization of a mouse with these partially (approximately 15%) purified hormone-receptor complexes allowed the preparation of 20 different hybridomas, each secreting antireceptor antibodies. The latter were used for receptor characterization. Immunoblot of testicular membrane extracts or of purified receptor preparations showed the presence of a major band at approximately 85,000 mol wt and minor bands at approximately 68,000 mol wt and approximately 48-45,000 mol wt. The width of all these bands suggested some microheterogeneity possibly due to glycosylation. The same approximately 85,000 mol wt receptor was seen in ovarian membranes, but no detectable antigen was observed in liver, muscle, and kidney membranes. An immunoaffinity method (using antibody LHR 38) was devised to purify the receptor in a single step. This demonstrated that the purified receptor preparation did not contain any protein component other than those detected by immunoblot. Comparison of receptors purified by immunoaffinity chromatography using either antireceptor or antihormone monoclonal antibodies showed in both cases the presence of the 85,000 mol wt and 48-45,000 mol wt species, but the absence, in the latter case, of the 68,000 mol wt species. This suggests that the 68,000 mol wt receptor cannot bind hormone and does not form oligomers with other receptor species.

Animals↗
PubMed1989

Cloning and sequencing of porcine LH-hCG receptor cDNA: variants lacking transmembrane domain.

Complementary DNA clones, encoding the LH-hCG (luteinizing hormone-human choriogonadotropic hormone) receptor were isolated by screening a lambda gt11 library with monoclonal antibodies. The primary structure of the protein was deduced from the DNA sequence analysis; the protein contains 696 amino acids with a putative signal peptide of 27 amino acids. Hydropathy analysis suggests the existence of seven transmembrane domains that show homology with the corresponding regions of other G protein-coupled receptors. Three other types of clones corresponding to shorter proteins were observed, in which the putative transmembrane domain was absent. These probably arose through alternative splicing. RNA blot analysis showed similar patterns in testis and ovary with a major RNA of 4700 nucleotides and several minor species. The messenger RNA was expressed in COS-7 cells, yielding a protein that bound hCG with the same affinity as the testicular receptor.

Amino Acid Sequence↗
PubMed1989

Novel monoclonal antibodies against human uterine progesterone receptor. Mapping of receptor immunogenic domains.

Progesterone receptor was purified in a single step from human uteri using immunoaffinity chromatography with monoclonal antibodies raised against the rabbit receptor. A total of 39 monoclonal antibodies were prepared against the human receptor and characterized. Immunoblot experiments using crude uterine cytosol or purified receptor showed that the antibodies belonged to three groups: they recognized either a single receptor species (apparent molecular mass 110 kDa), two species (110 and 79 kDa) or three species (110, 79 and 65 kDa). The species specificity of the antibodies was very variable; some recognized only the human receptor, others interacted with several mammalian receptors (rabbit, guinea pig and rat), while a single one also cross-reacted with the chick receptor. The epitopes recognized by 15 of the antibodies showing the strongest affinity for the human receptor were mapped using a method recently described [Lorenzo, Jolivet & Milgrom (1988) Eur. J. Biochem. 176, 53-60] which involves immunoprecipitation of C-terminally truncated proteins obtained by transcription and translation of cloned cDNA in vitro. The antibodies recognized five different regions of the receptor, all localized on the N-terminal half of the protein. None of the antibodies interacted with an epitope present in the DNA-binding or steroid-binding regions of the receptor. Comparison of the pattern of receptor species recognized by the antibodies and the localization of their epitopes showed that the 79 and 65 kDa receptor species were derived from the 110 kDa form by deletion of its N-terminal part. The N-terminus of the 79 kDa species was found to lie between amino acids 121 and 208, and that of the 65 kDa species between amino acids 208 and 296.

Antibodies, Monoclonal↗
PubMed1989

Immunohistochemical evidence of the presence of estrogen and progesterone receptors in the same neurons of the guinea pig hypothalamus and preoptic area.

Estrogen and progesterone interact in the regulation of various brain functions including mechanisms controlling gonadotropin secretion and female sexual behavior. Various methods have been used to map the regions where these hormones act and where specific receptors can be detected. However, it remains unknown if both steroids act on the same neuron or if there are neural populations responding to either one or the other of these hormones To answer this question, we used various immunocytochemical procedures to detect estrogen and progesterone receptors (ER-IR and PR-IR) on the same histological section, taking advantage of the fact that anti-ER monoclonal antibodies were raised from rats whereas anti-PR monoclonal antibodies were raised from mice. Initial experiments showed that the number of cells displaying ER and PR immunoreactivity changed with hormonal treatment. Prolonged treatment of ovariectomized guinea pigs with high doses of estradiol benzoate (EB) (10 or 15 micrograms/day for 4 or 6 days) increased the number of PR-positive cells in the preoptic area and the hypothalamus. Inversely, with this estrogen priming regimen the number of ER-positive cells decreased, as did the immunostaining intensity in their nuclei. With a lower dose of estrogen administered for a shorter period (2-microgram dose of EB for 2 days) the two receptor populations could be easily observed. Under these hormonal conditions, the sequential procedure revealed that the vast majority of cells containing ER-IR in the preoptic area (nucleus preopticus periventricularis, medialis) and the mediobasal hypothalamus (nucleus periventricularis, arcuatus, ventrolateral part of nucleus ventromedialis and premamillaris) showed PR immunoreactivity. This was true regardless of the order in which dual immunocytochemical staining was performed. There were, however, a few ER-positive/PR-negative cells in these regions. However, only ER-positive neurons were found in the n. interstitialis stria terminalis, the n. amygdaloideus medialis and the n. supraopticus. Thus, in guinea pigs receiving moderate doses of estrogen, all PR-positive cells contain ER-IR whereas there is a population of ER-positive cells which are devoid of PR-IR.

Animals↗
PubMed1989

Beta 2-adrenoceptor response in the rat uterus at the end of gestation and after induction of labor with RU 486.

To study the relationship between the progesterone environment and beta-adrenoceptors in the myometrium, rats were treated with the antiprogestin RU 486 (10 mg per rat) at 08:30 h on day 21 of gestation. Under these conditions, more than 60% of animals delivered within 24 h after this treatment, while none of the control animals delivered within the same time period. beta-Adrenoceptors were identified using the radiolabeled antagonist (-)-[125I] iodocyanopindolol. The density (Bmax approximately 33-45 fmol/mg protein) and the affinity (KD approximately 0.105-0.106 nM) were not changed (during the late stages of gestation) in RU 486 treated rats compared with control rats. These results were correlated with the relaxation of longitudinal and circular strips of myometrium placed in high KC1 medium and exposed to beta-adrenoceptor agonists. The adrenoceptors implicated in the relaxation of myometrial strips were mainly of the beta 2-subtype. There was no difference in their affinity between control and RU 486 treated rats. Mean pA2 values were 8.46 for propranolol and 8.27 for ICI 118-551 against salbutamol. Altogether these results indicate in the rat that the blockade of the action of progesterone at its receptor site by RU 486 did not modify either the affinity or the sensitivity of beta 2-adrenoceptors in the myometrium, although it induced parturition.

Albuterol↗
PubMed1988

A rapid method of epitope mapping. Application to the study of immunogenic domains and to the characterization of various forms of rabbit progesterone receptor.

A method is described to map contiguous epitopes recognized by monoclonal antibodies in the case when the cDNA for a protein has been cloned. The cDNA is inserted into an expression vector allowing its acellular transcription, followed by the translation of the resulting messenger RNA. C-terminally truncated species of the protein are either generated by cutting the cDNA with restriction enzymes or arise spontaneously through stops occurring during translation of the mRNA. If necessary, progressive digestion by Bal31 of the cDNA can be used to produce an array of polypeptides having different C-terminal lengths. Immunoprecipitation then allows determination of the shortest protein recognized by the monoclonal antibody and thus to define its site of action. This method has been applied to the study of a group of selected monoclonal antibodies among the 59 that have been prepared against the rabbit progesterone receptor. Four immunogenic domains were identified lying between amino acids 1-60, 101-110, 295-325 and 370-396. There were no antibodies directed against the DNA-binding or the steroid-binding regions of the receptor. This is probably due to the high degree of amino acid sequence conservation in these domains, observed when comparing receptors from different species. The antibodies cross-reacting with highest affinity for the human receptor interact with the first immunogenic domain (amino acids 1-60). The 79-kDa form ('subunit A') of the receptor was shown to lack the two more N-terminally localized immunogenic domains (amino acids 1-60 and 101-110). The 65-kDa form lacked, in addition, the domain localized between amino acids 295 and 325. These two forms of the receptor thus correspond to deletions of the N-terminal part of the protein.

Animals↗