Transthyretin amyloid polyneuropathy in France: A cross-sectional study with 413 patients and real-world tafamidis meglumine use (2009-2019)

OBJECTIVE

We aimed to describe characteristics of patients with ATTR variant polyneuropathy (ATTRv-PN) and ATTRv-mixed and assess the real-world use and safety profile of tafamidis meglumine 20mg.

METHODS

Thirty-eight French hospitals were invited. Patient files were reviewed to identify clinical manifestations, diagnostic methods, and treatment compliance.

RESULTS

Four hundred and thirteen patients (296 ATTRv-PN, 117 ATTRv-mixed) were analyzed. Patients were predominantly male (68.0%) with a mean age of 57.2±17.2 years. Interval between first symptom(s) and diagnosis was 3.4±4.3 years. First symptoms included sensory complaints (85.9%), dysautonomia (38.5%), motor deficits (26.4%), carpal tunnel syndrome (31.5%), shortness of breath (13.3%), and unexplained weight loss (16.0%). Mini-invasive accessory salivary gland or punch skin and nerve biopsies were most common, with a performance of 78.8-100%. TTR genetic sequencing, performed in all patients, revealed 31 TTR variants. Tafamidis meglumine was initiated in 156/214 (72.9%) ATTRv-PN patients at an early disease stage. Median treatment duration was 6.00 years in ATTRv-PN and 3.42 years in ATTRv-mixed patients. Tafamidis was well tolerated, with 20 adverse events likely related to study drug among the 336 patients.

CONCLUSION

In France, ATTRv patients are usually identified early thanks to the national network and the help of diagnosis combining genetic testing and mini-invasive biopsies.

Upper limb onset of hereditary transthyretin amyloidosis is common in non-endemic areas

BACKGROUND AND PURPOSE

The aim is to describe an uncommon phenotype of hereditary ATTR neuropathy with upper limb onset.

METHODS

The French TTR Familial Amyloid Polyneuropathy database was used for a retrospective evaluation of 32 consecutive patients with upper limb onset of the neuropathy (study group) and they were compared to 31 Portuguese early-onset patients and 99 late-onset patients without upper limb onset.

RESULTS

Initial upper limb symptoms were mostly sensory. Lower limb symptoms began 2.3 ± 3 years after upper limb symptoms. Twenty-four (75%) patients were initially misdiagnosed, with 15 different diagnoses. More patients in the study group had a Neuropathy Impairment Score upper limb/lower limb ratio > 1 compared to the late-onset patient group. The study group had significantly more pronounced axonal loss in the median and ulnar motor nerves and the ulnar sensory and sural nerves. On radial nerve biopsies (n = 11), epineurial vessels were abnormal in six cases, including amyloid deposits in vessel walls (3/11), with vessel occlusion in two cases.

CONCLUSION

Upper limb onset of hereditary ATTR neuropathy is not rare in non-endemic areas. It is important to propose early TTR sequencing of patients with idiopathic upper limb neuropathies, as specific management and treatment are required.

NOBOX is a strong autosomal candidate gene in Tunisian patients with primary ovarian insufficiency

Premature ovarian insufficiency (POI) affects approximately 1% of women before the age of 40. Genetic contribution is a significant component of POI. In this context, heterozygous mutations in NOBOX, BMP15 and GDF9 have been reported. The objective of our study was to evaluate the prevalence of these genes mutations in 125 unrelated Tunisian patients diagnosed with POI. The screening of NOBOX gene revealed three missense mutations (p.Arg117Trp; p.Gly91Trp and p.Pro619Leu) in eight patients. These mutations were not found in a 200 ethnically matched women without fertility problem. The sequencing of BMP15 and GDF9 gene revealed only previously reported variants. In contrast to previous studies, the prevalence of BMP15 variations is not higher than in the control population. Conversely, 6.4% of the cases present a NOBOX mutations; this high prevalence strengthens the consideration of NOBOX gene as strong autosomal candidate for POI.

Array comparative genomic hybridization analysis of small supernumerary marker chromosomes in human infertility

Small supernumerary marker chromosomes (sSMC) are structurally abnormal chromosomes that cannot be unambiguously identified by conventional banding cytogenetics. This study describes four patients with sSMC in relation with infertility. Patient 1 had primary infertility. His brother, fertile, carried the same sSMC (patient 2). Patient 3 presented polycystic ovary syndrome and patient 4 primary ovarian insufficiency. Cytogenetic studies, array comparative genomic hybridization (CGH) and sperm analyses were compared with cases previously reported. sSMC corresponded to the 15q11.2 region (patients 1 and 2), the centromeric chromosome 15 region (patient 3) and the 21p11.2 region (patient 4). Array CGH showed 3.6-Mb gain for patients 1 and 2 and 0.266-Mb gain for patient 4. Sperm fluorescent in-situ hybridization analyses found ratios of 0.37 and 0.30 of sperm nuclei with sSMC(15) for patients 1 and 2, respectively (P < 0.001). An increase of sperm nuclei with disomy X, Y and 18 was noted for patient 1 compared with control and patient 2 (P < 0.001). Among the genes mapped in the unbalanced chromosomal regions, POTE B and BAGE are related to the testis and ovary, respectively. The implication of sSMC in infertility could be due to duplication, but also to mechanical effects perturbing meiosis.

Thymidine phosphorylase gene mutations in patients with mitochondrial neurogastrointestinal encephalomyopathy syndrome

The mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) syndrome is characterized by the association of gastrointestinal and neurological symptoms. It is a rare autosomal recessive mitochondrial disorder with multiple mitochondrial DNA deletions and/or depletion. It is caused by thymidine phosphorylase (TP) gene mutations resulting in a complete abolition of TP activity. We tested 31 unrelated patients presenting either with a complete MNGIE syndrome (8 patients), a severe intestinal pseudo-obstruction (10 patients), and multiple deletions and/or depletion of mitochondrial DNA (13 patients). All the tested patients presenting with a complete MNGIE had increased thymidine levels in plasma and urine, and no TP activity. The group with pseudo-obstruction syndrome had normal or partial reduction of TP activity. We found pathogenic mutations on TP gene only in the MNGIE syndrome group: all the MNGIE patients were compound heterozygous or homozygous for mutations in the TP gene. Eight of these mutations are yet unreported, confirming the lack of genotype/phenotype correlation in this syndrome. Enzymatic activity and thymidine level are thus rapid diagnosis tests to detect MNGIE affected patients prior to genetic testing for patients with gastrointestinal symptoms.

The range of chronic demyelinating neuropathy of infancy: a clinico-pathological and genetic study of 15 unrelated cases

The concept of Dejerine-Sottas disease, which corresponds to presumed recessive demyelinating neuropathies with onset in infancy, remains controversial. To learn more on the subject, we performed a clinico-pathological and molecular genetic study in 15 unrelated patients with the Dejerine-Sottas phenotype seen over a 16 year period. There were 12 females and 3 males, born to asymptomatic parents. Study of the PMP22, P0 and Egr2 genes was performed in all cases and 14 underwent a nerve biopsy. First manifestations of neuropathy occurred before 3 years of age in all patients. An inherited disorder was suspected in 10 patients, because of their family history and/or disclosure of a molecular genetic defect in 4 of them. One patient had a recessively transmitted homozygous point mutation (Arg157Trp) of the PMP22 gene. A heterozygous duplication of the 17p11.2-12 segment was detected in one offspring of a consanguineous marriage. One patient carried a "de novo" heterozygous Ser72Leu substitution in the PMP22. A heterozygous double mutation of the P0 gene including a "de novo" Val42 deletion and an Ala221Thr substitution, maternally inherited, were found in an apparently sporadic case. No mutation of the Egr2 gene was identified. A neuropathy with focally folded myelin sheaths (CMT4B) was diagnosed in the nerve biopsy specimens of two patients. In five patients, the clinico-pathological findings along with the absence of an identified mutation suggested the diagnosis of chronic inflammatory demyelinating polyneuropathy of infantile onset. Our findings illustrate the genetic heterogeneity of cases with identified mutations, the scarcity of cases with "demonstrated" recessive transmission and the likelihood of early acquired chronic inflammatory demyelinating polyneuropathy in several patients.

Phe 84 deletion of the PMP22 gene associated with hereditary motor and sensory neuropathy HMSN III with multiple cranial neuropathy: clinical, neurophysiological and magnetic resonance imaging findings

Hereditary motor and sensory neuropathy (HMSN) is a heterogeneous group of peripheral neuropathies which are diagnosed on the basis of clinical, electrophysiological and neuropathological findings. Among the hypertrophic demyelinating neuropathies, HMSN III is the most severe. It is often associated with de novo mutations in the genes encoding for peripheral myelin proteins. While peripheral nerve hypertrophy is an expected finding in HMSN III, cranial nerve hypertrophy is exceptional. Here we describe a mutation in the PMP22 gene in a 19-year-old man with infantile onset of sensory motor polyneuropathy without family history and multiple cranial nerve hypertrophy shown by cranial magnetic resonance imaging.

Peripheral neuropathy with hypomyelination, chronic intestinal pseudo-obstruction and deafness: a developmental "neural crest syndrome" related to a SOX10 mutation

We describe the case of a girl with an unusual congenital phenotype, combining peculiar peripheral nerve lesions with hypomyelination, chronic intestinal pseudoobstruction, and deafness. She was found to have a de novo heterozygous frameshift mutation in the gene encoding the SOX10 transcription factor. The likely role of SOX10 in determining the fate of Schwann cells during early embryogenesis may explain the peripheral nervous system developmental disorder observed in this patient.

[Regulation of the differentiation and proliferation of smooth muscle cells by the sex hormones]

Steroids effects are mediated by their receptors. These proteins define the large family of steroid hormone receptors, characterized by the presence of 3 functional domains: a transactivation domain, a DNA-binding domain and a ligand-binding domain. Receptor activation induces the modulation of transcription of specific genes, and as a consequence, the modulation of production of specific proteins. Sex steroid receptors are located in the nucleus. This nuclear localization is in fact a dynamic situation, resulting from a continuous shuttling of the receptor between the cytoplasm and the nucleus. The recent discovery that an additional estrogen receptor is present in various tissues has advanced our understanding of the mechanism underlying estrogen signalling. Non genomic effects of steroids have also been described. Sex steroids inhibit proliferation of smooth muscle cells. On the contrary, they stimulate proliferation of tumoral muscle cells. The mechanisms of sex steroid effects on cellular proliferation are complex, and may involve transcriptional or non transcriptional phenomena.

[Specific modulators of estrogen action]

Selective estradiol receptor modulators (SERMs) are specific modulators of estradiol action. They are used in therapeutics to obtain an estrogenic effect on certain cells and an antiestrogenic effect on other cells. Recent progress in the knowledge of the mechanism of action of estradiols implies that new molecules could be designed. This progress involves the cloning of a new estradiol receptor, ER beta, the discovery of co-activators and the elucidation of their molecular mechanism of action, and the crystallization of the ligand binding domain in the presence of an agonist or an antagonist.

The Roussy-Lévy family: from the original description to the gene

In 1926, Roussy and Lévy described a large family whose members manifested an early onset dominantly inherited gait ataxia, pes cavus, and areflexia, which was eventually associated with distal muscle atrophy, postural tremor, and minor sensory loss. Slow nerve conduction and demyelination of nerve fibers with onion bulb formations in nerve biopsy specimens led to the Roussy-Lévy syndrome (RLS) being considered a variant of demyelinating Charcot-Marie-Tooth disease (CMT-1). In the present article, we report on the long-term follow-up, on nerve biopsy findings, and on the underlying molecular genetic defect in members of the original family studied by Roussy and Lévy. All patients were able to walk during their seventh decade of life. Morphologically, a chronic demyelinating neuropathy with the remarkable aspects of a focally hypertrophic myelin sheath and major loss of myelinated fibers was observed in nerve biopsy specimens of 3 members of this family. Molecular genetic testing identified a previously unknown heterozygous missense point mutation which yielded an Asn131Lys substitution in the extracellular domain of the myelin protein zero (P0). These findings show that the Roussy-Lévy family belongs to the CMT-1B subtype and has original morphological and genetic features.

[Estrogen biosynthesis and receptors]

Most of the enzymes involved in steroidogenesis belong to the family of cytochrome P 450. Most of the corresponding genes have been cloned. The key enzyme for estradiol biosynthesis is P 450 arom. Several germline mutations have been described. These observations have lead to reconsider the role of estradiol. Estradiol plays a key role in bone growth and mineralisation and in gonadotrope regulation in male. Moreover, the recent discovery that an additional estrogen receptor (ER beta) is present in various tissues has advanced our understanding of the mechanisms underlying estrogen signalling. It suggests the existence of two previously unrecognized pathways of estrogen signalling: via the ER beta subtype in tissues exclusively expressing this subtype and via the formation of heterodimers in tissues expressing both ER subtypes. Various models have been suggested as explanations for the stricking cell and promoter-specific effects of estrogens and antiestrogens, all on the basis of the assumption that only a single ER exists. These models have to be reconsidered. Moreover, new antiestrogens with improved therapeutic profiles could be designed.

[Steroid receptors and mechanism of action of sex steroids]

Steroid hormone receptors define a large family of proteins. Recently, a new estradiol receptor has been identified. This discovery suggests the existence of a previously unrecognized pathway of estrogen signalling. Moreover, it implies important pharmacological consequences. Receptors activation induces the modulation of transcription of specific genes. Proteins involved in this effect have been identified: coactivators, corepressors and cointegrators. Their mechanism of action have been characterized. They modify histone acetylation of the corresponding promotor. Sex steroid receptors are located in the nucleus. This nuclear localization is in fact a dynamic situation, resulting from a continuous shuttling of the receptor between the cytoplasm and the nucleus. Non genomic effects of steroids have also been described.

Recessive inheritance of a new point mutation of the PMP22 gene in Dejerine-Sottas disease

The existence of recessive transmission of Dejerine-Sottas disease, a severe demyelinating neuropathy of childhood, has been questioned, because only heterozygous mutations of the myelin proteins P0 or PMP22 genes have been identified in virtually all patients with this phenotype. We report on a family with 3 affected children with this phenotype, born to clinically and electrophysiologically unaffected parents. All 3 children carried a previously unknown homozygous missense point mutation (Arg157Trp) of the PMP22 gene. The parents were heterozygous for the same mutation. These findings demonstrate the occurrence of recessive transmission in this setting.

Mechanisms of progesterone receptor export from nuclei: role of nuclear localization signal, nuclear export signal, and ran guanosine triphosphate

Steroid hormone receptors are, in most cases, mainly nuclear proteins that undergo a continuous nucleocytoplasmic shuttling. The mechanism of the nuclear export of these proteins remains largely unknown. To approach this problem experimentally in vivo, we have prepared cell lines permanently coexpressing the wild-type nuclear progesterone receptor (PR) and a cytoplasmic receptor mutant deleted of its nuclear localization signal (NLS) [(deltaNLS)PR]. Each receptor species was deleted from the epitope recognized by a specific monoclonal antibody, thus allowing separated observation of the two receptor forms in the same cells. Administration of hormone provoked formation of heterodimers during nucleocytoplasmic shuttling and import of (deltaNLS)PR into the nucleus. Washing out of the hormone allowed us to follow the export of (deltaNLS)PR into the cytoplasm. Microinjection of BSA coupled to a NLS inhibited the export of (deltaNLS)PR. On the contrary, microinjection of BSA coupled to a nuclear export signal (NES) was without effect. Moreover, leptomycin B, which inhibits NES-mediated export, was also without effect. tsBN2 cells contain a thermosensitive RCC1 protein (Ran GTP exchange protein). At the nonpermissive temperature, the nuclear export of (deltaNLS)PR could be observed, whereas the export of NES-BSA was suppressed. Microinjection of GTPgammaS confirmed that the export of (deltaNLS)PR was not dependent on GTP hydrolysis. These experiments show that the nuclear export of PR is not NES mediated but probably involves the NLS. It does not involve Ran GTP, and it is not dependent on the hydrolysis of GTP. The nucleocytoplasmic shuttling of steroid hormone receptors thus appears to utilize mechanisms different from those previously described for some viral, regulatory, and heterogeneous ribonuclear proteins.

The Ernst Schering Poster Award. Intracellular traffic of steroid hormone receptors

The signal responsible for the nuclear localization of the progesterone receptor has been characterized. It is a complex signal. The study of the mechanism of this nuclear localization has revealed that the receptor continuously shuttles between nucleus and the cytoplasm. The receptor diffuses into the cytoplasm and is constantly and actively transported back into the nucleus. The same phenomenon exists for estradiol and glucocorticoid receptors. The mechanism of entry of proteins into the nucleus is well documented, whereas the mechanism of their outward movement to the cytoplasm is not understood. We have grafted different nuclear localization signals (NLSs) onto beta-galactosidase and have studied the traffic of this protein using heterokaryons and microinjection experiments. We have demonstrated that the same NLSs are involved in both the inward and the outward movement of proteins through the nuclear membrane. These results suggest that the nucleocytoplasmic shuttling may be a general phenomenon for nuclear proteins that could possibly undergo modifications in the cytoplasm and exert some biological activities there. These conclusions also imply that at least part of the cellular machinery involved in the nuclear import of proteins may function bidirectionally. Using these techniques, we have shown that the two major antiprogestins, RU486 and ZK98299, act at the same distal level of hormone action.

Effect of PML and PML-RAR on the transactivation properties and subcellular distribution of steroid hormone receptors

PML (promyelocytic leukemia) is a protein involved in the t (15;17) translocation of promyelocytic leukemia and is mainly localized in nuclear bodies. Here we show that PML exerts a very powerful enhancing activity (up to 20-fold) on the transactivating properties of the progesterone receptor (PR) and has a similar effect on several other steroid hormone receptors. There is probably a direct or indirect interaction between PR and PML, because when the latter was expressed at high concentrations it shifted PR into the nuclear bodies. The use of deletion mutants showed that both activation functions (AF1 and AF2) of PR as well as the coiled coil and His-Cys-rich domains of PML were required for transcriptional enhancement. The fusion protein PML-RAR which is not localized in nuclear bodies, also enhanced the transactivating activity of PR, but this effect was totally suppressed by the administration of retinoic acid. PML, which is ubiquitously expressed, may thus be involved in the transactivation properties of steroid hormone receptors. This mechanism may also play a role in the oncogenic properties of PML-RAR and in their suppression by retinoic acid.

Nuclear localization signals also mediate the outward movement of proteins from the nucleus

Several nuclear proteins, including steroid hormone receptors, have been shown to shuttle continuously between the nucleus and the cytoplasm. The mechanism of entry of proteins into the nucleus is well documented, whereas the mechanism of their outward movement into the cytoplasm is not understood. We have grafted the nuclear localization signals of the progesterone receptor or the simian virus 40 large tumor antigen onto beta-galactosidase. These additions were shown to impart to the protein the ability to shuttle between the nucleus and the cytoplasm. Microinjected proteins devoid of a nuclear localization signal were unable to exit from the nucleus. The same nuclear localization signals are thus involved in both the inward and the outward movement of proteins through the nuclear membrane. We also show that although the nuclear import requires energy, the nuclear export does not. These results suggest that the nucleocytoplasmic shuttling may be a general phenomenon for nuclear proteins that could possibly undergo modifications in the cytoplasm and exert some biological activities there. These conclusions also imply that at least part of the cellular machinery involved in the nuclear import of proteins may function bidirectionally.

Cytoplasmic-nuclear trafficking of progesterone receptor. In vivo study of the mechanism of action of antiprogestins

The signal responsible for the nuclear localization of the progesterone receptor has been characterized. The study of the mechanism of this nuclear localization has revealed that the receptor continuously shuttles between the nucleus and the cytoplasm. The receptor diffuses into the cytoplasm and is constantly and actively transported back into the nucleus. Preliminary evidence suggests that the same mechanism exists for estradiol and glucocorticoid receptors. Experiments designed to study the traffic of steroid hormone receptors have been applied to the determination of the molecular mechanism of action of antisteroids. Using these techniques, we have shown that two major antiprogestins, RU486 and ZK98299, act at the same point in the cell as the hormone.

In vivo functional protein-protein interaction: nuclear targeted hsp90 shifts cytoplasmic steroid receptor mutants into the nucleus

In target tissue extracts, heat shock protein hsp90 has been found associated to all unliganded steroid receptors. Modulation of important functions of these receptors, including prevention of DNA binding and optimization of transcriptional activity, has been attributed to hsp90. However no unequivocal in vivo demonstration of interaction between receptors and hsp90 has been presented. We targeted chicken hsp90, a mainly cytoplasmic protein, with the nucleoplasmin nuclear localization signal (90NLS). After transfection into COS-7 cells, 90NLS was found in the nucleus with specific immunofluorescence and confocal microscopy techniques. A human glucocorticosteroid receptor mutant devoid of NLS sequence was also expressed in COS-7 cells and found exclusively cytoplasmic. Coexpression of 90NLS and of the cytoplasmic human glucocorticosteroid receptor mutant led to complete nuclear localization of the receptor, indicating its piggyback transport by 90NLS and thus physical and functional interaction between the two proteins in the absence of hormone. The same nuclear localization was obtained after cotransfection of 90NLS and a cytoplasmic rabbit progesterone receptor mutant. Finally, coexpression of wild-type rabbit progesterone receptor (nuclear) and wildtype hsp90 (cytoplasmic) into COS-7 cells provoked partial relocalization of hsp90 into the nucleus. These experiments lay the groundwork on which to study hsp90 as a chaperone, regulating activities of steroid receptors and possibly participating in their nuclear-cytoplasmic shuttling.

Cytoplasmic-nuclear trafficking of steroid hormone receptors

The nuclear localization of most steroid hormone receptors reflects a dynamic process: the receptor constantly diffuses out of the nucleus and is reimported by an active mechanism. The outward movement from the nucleus of the receptors and of other nuclear proteins is also mediated by the nuclear localization signals.

In vivo evidence against the existence of antiprogestins disrupting receptor binding to DNA

The binding of a steroid hormone to its receptor elicits a sequence of events: activation of the receptor (probably through dissociation from a complex of heat shock proteins), dimerization, binding to hormone responsive elements, and finally modulation of gene transcription. RU 486, the first antiprogestin studied, has been shown to act at the last step of this sequence: provoking an inefficient binding of the receptor to hormone responsive elements. Recently, based on in vitro studies, it has been proposed that ZK 98299 was the prototype of a second class of antiprogestins that were supposed to act through disruption of the binding to DNA. We have devised methods allowing us to study the various steps of agonist or antagonist action in vivo. We show here that RU 486 and ZK 98299 have the same effects on receptor activation, dimerization, and binding to hormone responsive elements; differences in their action are explained by the 10-fold difference in their affinity for the receptor (ZK 98299 having the lower affinity).

Mechanisms of nuclear localization of the progesterone receptor

Deletion mutants of the rabbit progesterone receptor were used to identify two major mechanisms of its nuclear localization. A putative signal sequence, homologous to that of the SV40 large T antigen, was localized around amino acids 638-642 and was shown to be constitutively active. When amino acids 638-642 were deleted, the receptor became cytoplasmic but could be shifted into the nucleus by the addition of hormone (or anti-hormone), it was almost fully active. A second putative nuclear localization signal is located in the DNA binding domain activated either through ligand binding or through production of constitutive receptor. By deleting epitopes recognized by monoclonal antibodies, it was possible to follow different receptor mutants inside the same cells. In the absence of ligand the receptor was transferred into the nucleus as a monomer. After administration of hormone (or anti-hormone) a "cytoplasmic" monomer was transferred into the nucleus through interaction with a "nuclear" monomer. These interactions occurred through the steroid binding domains of both monomers.

Nucleocytoplasmic shuttling of the progesterone receptor

The nuclear localization of the progesterone receptor is mediated by two signal sequences: one is constitutive and lies in the hinge region (between the DNA and steroid binding domains), the other is hormone dependent and is localized in the second zinc finger of the DNA binding domain. The use of various inhibitors of energy synthesis in cells expressing permanently or transiently the wild-type receptor or a receptor mutated within the nuclear localization signals, demonstrated that the nuclear residency of the receptor reflects a dynamic situation: the receptor diffusing into the cytoplasm and being constantly and actively transported back into the nucleus. The existence of this nucleo-cytoplasmic shuttle mechanism was confirmed by receptor transfer from one nucleus to the other in heterokaryons. Preliminary evidence was obtained, using oestrogen receptor, that this phenomenon may be of general significance for steroid receptors.

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.

Cloning, sequencing and expression of human TSH receptor

Complementary cDNA clones encoding the TSH (thyroid stimulatory hormone) receptor were isolated from a human thyroid lambda gt10 library using Iow stringency hybridization with LH/hCG (luteinizing hormone-human choriogonadotropic hormone) receptor probes. Sequencing of the clones showed a 764 amino acid open reading frame. The first 21 amino acids probably correspond to a signal peptide, the mature protein thus contains 743 amino acids (calculated molecular weight: 84,501 daltons). Its putative structure consists of a 394 amino acid extracellular domain, a 266 amino acid membrane spanning domain with 7 putative transmembrane segments and a 83 amino acid intracellular domain. A high degree of homology is observed with LH/hCG receptor suggesting the definition of a new subfamily of G-protein coupled receptors. Computer search showed the presence in the putative third intracellular loop of a motif resembling that described in the non receptor type protein tyrosine kinases (c-src, c-yes, c-fgr, etc...). RNA blots showed that the receptor messenger RNA consists of two major species of 4300 and 3900 nucleotides. The cDNA was inserted into an expression vector and after transfection into COS 7 cells it was shown to produce a functional TSH receptor.

Structural and functional studies of mammalian progesterone receptors

During the past years there has been an improvement in our understanding of the molecular mechanism of action of the progesterone receptor (PR). This was due to the obtention of monoclonal antibodies against PR which allowed the first structural analyses and led to the cloning of the genes.

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.

Mechanisms of nuclear localization of the progesterone receptor: evidence for interaction between monomers

Deletion mutants of the rabbit progesterone receptor were used to identify two major mechanisms of its nuclear localization. A putative signal sequence, homologous to that of the SV40 large T antigen, was localized around amino acids 638-642 and shown to be constitutively active. When amino acids 638-642 were deleted, the receptor became cytoplasmic but could be shifted into the nucleus by the addition of hormone (or anti-hormone); it was almost fully active. The second mechanism consisted of the activation of the DNA binding domain. By deleting epitopes recognized by monoclonal antibodies, it was possible to follow different receptor mutants inside the same cells. In the absence of ligand, the receptor was transferred into the nucleus as a monomer. After administration of hormone (or anti-hormone) a "cytoplasmic" monomer was transferred into the nucleus through interaction with a "nuclear" monomer. These interactions occurred through the steroid binding domains of both monomers.

Receptors bound to antiprogestin from abortive complexes with hormone responsive elements

The mechanism of action of antisteroids is not understood and explanations of their antagonistic activity have been sought at all levels of hormone action. It has been proposed that antisteroids, after binding to receptor, trap it into a non-activated (non DNA-binding) form possibly through interaction with a heat-shock protein of relative molecular mass (Mr) 90,000 (90 K), or that the antisteroids provoke binding of receptor to nonspecific DNA sites but not to hormone responsive elements (HREs), or that the antisteroid-receptor complexes can bind to HREs but form abortive complexes that fail to regulate transcription. We have constructed a deleted cDNA encoding a mutant form of rabbit progesterone receptor which exhibits constitutive activity, that is, binds to HREs in the absence of hormone and thus bypasses the first two steps discussed above. Co-transfection experiments allowed the expression of both constitutive and wild-type receptors in the same recipient cells. Antiprogestin RU486-wild-type receptor complexes completely suppressed the activity of the constitutive receptor on a reporter gene, showing that the inhibition is at the level of their common responsive elements.

Complete amino acid sequence of the human progesterone receptor deduced from cloned cDNA

A lambda gt10 library containing DNAs complementary to messenger RNAs from human breast cancer T47-D cells was constructed and screened with a cDNA probe encoding the rabbit progesterone receptor. Four overlapping clones have been sequenced. The open reading frame corresponds to a protein of 933 amino acids with a molecular weight of 98,868 Da. The cysteine rich basic region supposed to be involved in DNA binding is completely homologous in the human and rabbit receptors, whereas the C-terminal end, where hormone binding is thought to take place, differs by a single amino acid change. The human progesterone receptor is characterized, as is the rabbit receptor, by the very high proline content of its N-terminal region. When mRNAs from either human breast cancer cell lines T47-D and MCF-7 or from normal human uterus tissue were blotted and probed with the cloned cDNA, four main bands were observed (5100, 4300, 3700, and 2900 nucleotides).

Cloning and sequence analysis of rabbit progesterone-receptor complementary DNA

Two lambda gt11 clones containing fragments of cDNA encoding the rabbit progesterone receptor were isolated with the aid of monoclonal and monospecific polyclonal antireceptor antibodies. RNA gel blot analysis showed that the corresponding mRNA was approximately equal to 5900 nucleotides in size and present in the uterus, where its concentration was increased by estrogen treatment, and in the vagina. This mRNA was not detected in liver, in spleen, in intestine, and in kidney where the receptor protein is known to be absent or present in very small concentration. Cross-hybridizing clones were isolated from a lambda 10 library. The DNA was sequenced, and the primary structure of the progesterone receptor was deduced. It consists of 930 amino acids and contains a basic, cysteine-rich region (residues 568-645) with extensive homology to the glucocorticoid and estrogen receptors and the v-erbA oncogene protein. This region is followed by a C-terminal domain that is similar in size to the corresponding domains of the other steroid receptors and v-erbA and shows striking amino acid homology with the glucocorticoid receptor and significant homology with the estrogen receptor. In contrast, the region extending from the cysteine-rich segment toward the N terminus differed in size and amino acid sequence from that of the other receptors and v-erbA. This region had a high proline content in the progesterone receptor.