RESUMO
Sirolimus, also known as rapamycin, and its closely related rapamycin analog (rapalog) Everolimus inhibit "mammalian target of rapamycin complex 1" (mTORC1), whose activity is required for spermatogenesis. Everolimus is Food and Drug Administration approved for treating human patients to slow growth of aggressive cancers and preventing organ transplant rejection. Here, we test the hypothesis that rapalog inhibition of mTORC1 activity has a negative, but reversible, impact upon spermatogenesis. Juvenile (P20) or adult (P>60) mice received daily injections of sirolimus or Everolimus for 30 days, and tissues were examined at completion of treatment or following a recovery period. Rapalog treatments reduced body and testis weights, testis weight/body weight ratios, cauda epididymal sperm counts, and seminal vesicle weights in animals of both ages. Following rapalog treatment, numbers of differentiating spermatogonia were reduced, with concomitant increases in the ratio of undifferentiated spermatogonia to total number of remaining germ cells. To determine if even low doses of Everolimus can inhibit spermatogenesis, an additional group of adult mice received a dose of Everolimus â¼6-fold lower than a human clinical dose used to treat cancer. In these animals, only testis weights, testis weight/body weight ratios, and tubule diameters were reduced. Return to control values following a recovery period was variable for each of the measured parameters and was duration and dose dependent. Together, these data indicate rapalogs exerted a dose-dependent restriction on overall growth of juvenile and adult mice and negative impact upon spermatogenesis that were largely reversed; following treatment cessation, males from all treatment groups were able to sire offspring.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Everolimo/farmacologia , Fertilidade/efeitos dos fármacos , Espermatogênese/efeitos dos fármacos , Espermatogônias/efeitos dos fármacos , Animais , Masculino , CamundongosRESUMO
KEY POINTS: Breast cancer 1 early onset gene codes for the DNA repair enzyme, breast cancer type 1 susceptibility protein (BRCA1). The gene is prone to mutations that cause a loss of protein function. BRCA1/Brca1 has recently been found to regulate several cellular pathways beyond DNA repair and is expressed in skeletal muscle. Skeletal muscle specific knockout of Brca1 in mice caused a loss of muscle quality, identifiable by reductions in muscle force production and mitochondrial respiratory capacity. Loss of muscle quality was associated with a shift in muscle phenotype and an accumulation of mitochondrial DNA mutations. These results demonstrate that BRCA1 is necessary for skeletal muscle function and that increased mitochondrial DNA mutations may represent a potential underlying mechanism. ABSTRACT: Recent evidence suggests that the breast cancer 1 early onset gene (BRCA1) influences numerous peripheral tissues, including skeletal muscle. The present study aimed to determine whether induced-loss of the breast cancer type 1 susceptibility protein (Brca1) alters skeletal muscle function. We induced genetic ablation of exon 11 in the Brca1 gene specifically in the skeletal muscle of adult mice to generate skeletal muscle-specific Brca1 homozygote knockout (Brca1KOsmi ) mice. Brca1KOsmi exhibited kyphosis and decreased maximal isometric force in limb muscles compared to age-matched wild-type mice. Brca1KOsmi skeletal muscle shifted toward an oxidative muscle fibre type and, in parallel, increased myofibre size and reduced capillary numbers. Unexpectedly, myofibre bundle mitochondrial respiration was reduced, whereas contraction-induced lactate production was elevated in Brca1KOsmi muscle. Brca1KOsmi mice accumulated mitochondrial DNA mutations and exhibited an altered mitochondrial morphology characterized by distorted and enlarged mitochondria, and these were more susceptible to swelling. In summary, skeletal muscle-specific loss of Brca1 leads to a myopathy and mitochondriopathy characterized by reductions in skeletal muscle quality and a consequent kyphosis. Given the substantial impact of BRCA1 mutations on cancer development risk in humans, a parallel loss of BRCA1 function in patient skeletal muscle cells would potentially result in implications for human health.
Assuntos
Proteína BRCA1/genética , Mitocôndrias Musculares/patologia , Debilidade Muscular/genética , Músculo Esquelético/patologia , Animais , DNA Mitocondrial/genética , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mutação/genéticaRESUMO
BACKGROUND: Claudins are a family of tight junction (TJ) membrane proteins involved in a broad spectrum of human diseases including cancer. Claudin-7 is a unique TJ membrane protein in that it has a strong basolateral membrane distribution in epithelial cells and in tissues. Therefore, this study aims to investigate the functional significance of this non-TJ localization of claudin-7 in human lung cancer cells. METHODS: Claudin-7 expression was suppressed or deleted by lentivirus shRNA or by targeted-gene deletion. Cell cycle analysis and antibody blocking methods were employed to assay cell proliferation and cell attachment, respectively. Electron microscopy and transepthelial electrical resistance measurement were performed to examine the TJ ultrastructure and barrier function. Co-immunolocalization and co-immunoprecipitation was used to study claudin-7 interaction with integrin ß1. Tumor growth in vivo were analyzed using athymic nude mice. RESULTS: Claudin-7 co-localizes and forms a stable complex with integrin ß1. Both suppressing claudin-7 expression by lentivirus shRNA in human lung cancer cells (KD cells) and deletion of claudin-7 in mouse lungs lead to the reduction in integrin ß1 and phospho-FAK levels. Suppressing claudin-7 expression increases cell growth and cell cycle progression. More significantly, claudin-7 KD cells have severe defects in cell-matrix interactions and adhere poorly to culture plates with a remarkably reduced integrin ß1 expression. When cultured on uncoated glass coverslips, claudin-7 KD cells grow on top of each other and form spheroids while the control cells adhere well and grow as a monolayer. Reintroducing claudin-7 reduces cell proliferation, upregulates integrin ß1 expression and increases cell-matrix adhesion. Integrin ß1 transfection partially rescues the cell attachment defect. When inoculated into nude mice, claudin-7 KD cells produced significantly larger tumors than control cells. CONCLUSION: In this study, we identified a previously unrecognized function of claudin-7 in regulating cell proliferation and maintaining epithelial cell attachment through engaging integrin ß1.
Assuntos
Claudinas/metabolismo , Integrinas/metabolismo , Neoplasias Pulmonares/metabolismo , Transdução de Sinais , Animais , Adesão Celular , Ciclo Celular , Linhagem Celular Tumoral , Proliferação de Células , Claudinas/genética , Modelos Animais de Doenças , Expressão Gênica , Técnicas de Silenciamento de Genes , Xenoenxertos , Humanos , Integrina beta1/genética , Integrina beta1/metabolismo , Integrinas/genética , Neoplasias Pulmonares/genética , Camundongos , Ligação ProteicaRESUMO
In mammals, most neonatal male germ cells (prospermatogonia) are quiescent and located in the center of the testis cords. In response to an unknown signal, prospermatogonia transition into spermatogonia, reenter the cell cycle, divide, and move to the periphery of the testis cords. In mice, these events occur by 3-4 days postpartum (dpp), which temporally coincides with the onset of retinoic acid (RA) signaling in the neonatal testis. RA has a pivotal role in initiating germ cell entry into meiosis in both sexes, yet little is known about the mechanisms and about cellular changes downstream of RA signaling. We examined the role of RA in mediating the prospermatogonia-to-spermatogonia transition in vivo and found 24 h of precocious RA exposure-induced germ cell changes mimicking those that occur during the endogenous transition at 3-4 dpp. These changes included: 1) spermatogonia proliferation; 2) maturation of cellular organelles; and 3), expression of markers characteristic of differentiating spermatogonia. We found that germ cell exposure to RA did not lead to cellular loss from apoptosis but rather resulted in a delay of â¼2 days in their entry into meiosis. Taken together, our results indicate that exogenous RA induces multiple hallmarks of the transition of prospermatogonia to spermatogonia prior to their entry into meiosis.
Assuntos
Animais Recém-Nascidos/fisiologia , Maturação do Esperma/efeitos dos fármacos , Espermatogônias/efeitos dos fármacos , Tretinoína/farmacologia , Proteínas Adaptadoras de Transdução de Sinal/biossíntese , Animais , Apoptose/efeitos dos fármacos , Biomarcadores/metabolismo , Contagem de Células , Proliferação de Células/efeitos dos fármacos , Sistema Enzimático do Citocromo P-450/biossíntese , Sistema Enzimático do Citocromo P-450/genética , Técnica Indireta de Fluorescência para Anticorpo , Complexo de Golgi/efeitos dos fármacos , Masculino , Meiose/efeitos dos fármacos , Camundongos , Microscopia Eletrônica , Mitocôndrias/efeitos dos fármacos , Organelas/efeitos dos fármacos , Reação em Cadeia da Polimerase em Tempo Real , Ácido Retinoico 4 Hidroxilase , Contagem de Espermatozoides , Espermatogênese , Testículo/citologia , Testículo/efeitos dos fármacos , Testículo/ultraestrutura , Fixação de TecidosRESUMO
Smooth muscle cells maintain filaments of actin and myosin in the presence of ATP, although dephosphorylated myosin filaments and actin-myosin interactions are unstable under those conditions in vitro. Several proteins that stabilize myosin filaments and that stabilize actin-myosin interactions have been identified. Fesselin or synaptopodin 2 appears to be another such protein. Rapid kinetic measurements and electron microscopy demonstrated that fesselin, isolated from turkey gizzard muscle, reduced the rate of dissociation of myosin filaments. Addition of fesselin increased both the length and thickness of myosin filaments. The rate of detachment of myosin, but not heavy meromyosin, from actin was also greatly reduced by fesselin. Data from this study suggest that fesselin stabilizes myosin filaments and tethers myosin to actin. These results support the view that one role of fesselin is to organize contractile units of myosin and actin.
Assuntos
Actinas/química , Actomiosina/química , Trifosfato de Adenosina/metabolismo , Proteínas Aviárias/química , Citoesqueleto/química , Proteínas de Membrana/química , Proteínas dos Microfilamentos/química , Miosinas de Músculo Liso/química , Actinas/metabolismo , Actinas/ultraestrutura , Actomiosina/metabolismo , Actomiosina/ultraestrutura , Animais , Proteínas Aviárias/isolamento & purificação , Proteínas Aviárias/metabolismo , Proteínas Aviárias/ultraestrutura , Citoesqueleto/metabolismo , Citoesqueleto/ultraestrutura , Moela das Aves , Cinética , Proteínas de Membrana/isolamento & purificação , Proteínas de Membrana/metabolismo , Proteínas de Membrana/ultraestrutura , Proteínas dos Microfilamentos/isolamento & purificação , Proteínas dos Microfilamentos/metabolismo , Proteínas dos Microfilamentos/ultraestrutura , Microscopia Eletrônica de Transmissão , Músculo Liso/metabolismo , Subfragmentos de Miosina/química , Subfragmentos de Miosina/isolamento & purificação , Subfragmentos de Miosina/metabolismo , Subfragmentos de Miosina/ultraestrutura , Estabilidade Proteica , Coelhos , Vesículas Secretórias/metabolismo , Vesículas Secretórias/ultraestrutura , Miosinas de Músculo Liso/isolamento & purificação , Miosinas de Músculo Liso/metabolismo , Miosinas de Músculo Liso/ultraestrutura , PerusRESUMO
BACKGROUND & AIMS: Integrity of the intestinal epithelium is required for nutrition absorption and defense against pathogens. Claudins are cell adhesion molecules that localize at tight junctions (TJs); many are expressed in the intestinal tract, but little is known about their functions. Claudin-7 is unique in that it has a stronger basolateral membrane distribution than other claudins, which localize primarily to apical TJs in the intestinal epithelium. We investigated the basolateral functions of claudin-7 and assessed the effects of disruption of Cldn7 in intestines of mice. METHODS: We generated Cldn7(-/-) mice and examined their intestines by histology, molecular and cellular biology, and biochemistry approaches. We performed gene silencing experiments in epithelial cell lines using small interfering RNAs (siRNAs). RESULTS: The Cldn7(-/-) mice had severe intestinal defects that included mucosal ulcerations, epithelial cell sloughing, and inflammation. Intestines of Cldn7(-/-) mice produced significantly higher levels of cytokines, the nuclear factor κB p65 subunit, and cyclooxygenase 2; they also up-regulated expression of matrix metalloproteinases (MMPs)-3 and -7. siRNA in epithelial cell lines showed that the increased expression of MMP-3 resulted directly from claudin-7 depletion, whereas that of MMP-7 resulted from inflammation. Electron microscopy analysis showed that intestines of Cldn7(-/-) mice had intercellular gaps below TJs and cell matrix loosening. Deletion of Cldn7 reduced expression and altered localization of the integrin α2 subunit in addition to disrupting formation of complexes of claudin-7, integrin α2, and claudin-1 that normally form in epithelial basolateral compartments of intestines. CONCLUSIONS: In mice, claudin-7 has non-TJ functions, including maintenance of epithelial cell-matrix interactions and intestinal homeostasis.
Assuntos
Claudinas/metabolismo , Inflamação/metabolismo , Mucosa Intestinal/metabolismo , Junções Íntimas/metabolismo , Animais , Células Cultivadas , Claudina-1 , Ciclo-Oxigenase 2/metabolismo , Integrina alfa2/metabolismo , Mucosa Intestinal/ultraestrutura , Metaloproteinase 3 da Matriz/metabolismo , Metaloproteinase 7 da Matriz/metabolismo , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Interferência de RNA , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Junções Íntimas/ultraestrutura , Fator de Transcrição RelA/metabolismoRESUMO
In the testis, F-actin structures are involved in spermatid nuclear remodeling and cytoplasm reduction, maintenance of the blood-testis barrier, support of the spermatogonial stem cell niche, and release of spermatids into the tubular lumen. To gain a better understanding of actin regulation in Sertoli-germ cell interactions, we investigated the expression of the Palladin (Palld) gene, which encodes a widely expressed phosphoprotein that localizes to actin-rich cytoplasmic structures, including focal adhesions, cell-cell junctions, podosomes, and stress fibers, and serves as a molecular scaffold to bundle actin fibers. In germ cells, PALLD was concentrated along the tubulin- and F-actin-containing cytoplasmic manchette that forms adjacent to the elongating spermatid nucleus during spermiogenesis. To our surprise, PALLD relocated from the cytoplasm to the nucleus of Sertoli cells in the juvenile testis, coincident with the onset of puberty, and this localization was maintained in the adult. We provide evidence that the 140 kDa isoform of PALLD predominates in Sertoli cells, and that it is apparently cleaved, with the C-terminus localizing to the nucleus while the N-terminus remains cytoplasmic. We investigated the nuclear localization of the C-terminus of PALLD and found that it is regulated by a putative nuclear export signal. These results provide the foundation for future work employing Sertoli cell- and spermatid-specific Palld-knockout mice to study diverse roles of PALLD as both a nuclear-actin regulatory protein and as a potential regulator of manchette formation during spermatogenesis.
Assuntos
Núcleo Celular/metabolismo , Proteínas do Citoesqueleto/metabolismo , Fosfoproteínas/metabolismo , Proteólise , Células de Sertoli/metabolismo , Citoesqueleto de Actina/metabolismo , Animais , Citoplasma/metabolismo , Masculino , Camundongos , Estrutura Terciária de Proteína , Células de Sertoli/citologia , Maturidade Sexual/fisiologia , Espermátides/citologia , Espermátides/metabolismo , Espermatogênese/fisiologiaRESUMO
10-Hydroxycamptothecin (HCPT) elicits strong anti-cancer effects and is less toxic than camptothecin (CPT), making it widely used in recent clinical trials. However, its low solubility limits its application as an effective anti-cancer therapy. In the present study we investigate the hypothesis that the unique water dispersible oleic acid-Triton X-100-coated Fe3O4 nanoparticles loaded with HCPT disrupt epithelial cell-cell junctions and induce human lung cancer cell apoptosis through the caspase-8 pathway. We characterized the HCPT-loaded nanoparticles and determined their effects on lung cancer cell viability and apoptosis by using immunofluorescence light microscopy and SDS-PAGE/immunoblots. We found that HCPT-loaded nanoparticles elicited an anti-proliferative effect in a dose-dependent manner. HCPT-loaded nanoparticles reduced the expression of cell-cell junction protein claudins, E-cadherin and ZO-1, and transmission electron microcopy demonstrated a disrupted tight junction ultrastructure. Transepithelial electric resistance was also reduced, indicating the reduction of tight junction functions. The HCPT-loaded nanoparticles increased phosphorylation of p38 and SAPK/JNK while it showed no effects on p42/44 MAP kinase. Compared with void Fe3O4 nanoparticles or HCPT drug alone, HCPT drug-loaded nanoparticles evoked synergistic effects by increasing cell apoptosis with enhanced activation of the caspase-8 pathway. Therefore, our current study highlights the potential of HCPT drug-loaded nanoparticles as a chemotherapeutic agent for increasing anti-cancer drug efficacy.
Assuntos
Antineoplásicos Fitogênicos/administração & dosagem , Camptotecina/análogos & derivados , Sistemas de Liberação de Medicamentos/métodos , Compostos Ferrosos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/patologia , Nanopartículas , Antineoplásicos Fitogênicos/farmacologia , Apoptose , Caderinas/biossíntese , Camptotecina/administração & dosagem , Camptotecina/farmacologia , Caspase 8/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Claudinas/biossíntese , Humanos , Immunoblotting , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Proteínas de Membrana/biossíntese , Fosfoproteínas/biossíntese , Fosforilação/efeitos dos fármacos , Junções Íntimas/efeitos dos fármacos , Junções Íntimas/ultraestrutura , Difração de Raios X , Proteína da Zônula de Oclusão-1 , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
This report compares cellular localization of fesselin in chicken smooth, skeletal and cardiac muscle tissues using affinity purified polyclonal fesselin antibodies. Western blot analyses revealed large amounts of fesselin in gizzard smooth muscle with lower amounts in skeletal and cardiac muscle. In gizzard, fesselin was detected by immunofluorescence as discrete cytoplasmic structures. Fesselin did not co-localize with talin, vinculin or caveolin indicating that fesselin is not associated with dense plaques or caveolar regions of the cell membrane. Immunoelectron microscopy established localization of fesselin within dense bodies. Since dense bodies function as anchorage points for actin and desmin in smooth muscle cells, fesselin may be involved in establishing cytoskeletal structure in this tissue. In skeletal muscle, fesselin was associated with desmin in regularly spaced bands distributed along the length of muscle fibers suggesting localization to the Z-line. Infrequently, this banding pattern was observed in heart tissue as well. Localization at the Z-line of skeletal and cardiac muscle suggests a role in contraction of these tissues.
Assuntos
Proteínas de Membrana/análise , Proteínas dos Microfilamentos/análise , Músculo Liso/química , Animais , Galinhas , Desmina/análise , Imunofluorescência , Moela das Aves/química , Fibras Musculares Esqueléticas/química , Músculo Esquelético/química , Miocárdio/químicaRESUMO
AIMS: Intracardiac injection of recombinant EphrinA1-Fc immediately following coronary artery ligation in mice reduces infarct size in both reperfused and non-reperfused myocardium, but the cellular alterations behind this phenomenon remain unknown. MAIN METHODS: Herein, 10 wk-old B6129SF2/J male mice were exposed to acute ischemia/reperfusion (30minI/24hrsR) injury immediately followed by intracardiac injection of either EphrinA1-Fc or IgG-Fc. After 24â¯h of reperfusion, sections of the infarct margin in the left ventricle were imaged via transmission electron microscopy, and mitochondrial function was assessed in both permeabilized fibers and isolated mitochondria, to examine mitochondrial structure, function, and energetics in the early stages of repair. KEY FINDINGS: At a structural level, EphrinA1-Fc administration prevented the I/R-induced loss of sarcomere alignment and mitochondrial organization along the Z disks, as well as disorganization of the cristae and loss of inter-mitochondrial junctions. With respect to bioenergetics, loss of respiratory function induced by I/R was prevented by EphrinA1-Fc. Preservation of cardiac bioenergetics was not due to changes in mitochondrial JH2O2 emitting potential, membrane potential, ADP affinity, efficiency of ATP production, or activity of the main dehydrogenase enzymes, suggesting that EphrinA1-Fc indirectly maintains respiratory function via preservation of the mitochondrial network. Moreover, these protective effects were lost in isolated mitochondria, further emphasizing the importance of the intact cardiomyocyte ultrastructure in mitochondrial energetics. SIGNIFICANCE: Collectively, these data suggest that intracardiac injection of EphrinA1-Fc protects cardiac function by preserving cardiomyocyte structure and mitochondrial bioenergetics, thus emerging as a potential therapeutic strategy in I/R injury.
Assuntos
Efrina-A1/farmacologia , Mitocôndrias Cardíacas/efeitos dos fármacos , Traumatismo por Reperfusão/tratamento farmacológico , Animais , Modelos Animais de Doenças , Técnicas Eletrofisiológicas Cardíacas/métodos , Metabolismo Energético , Efrina-A1/administração & dosagem , Masculino , Camundongos , Camundongos Endogâmicos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Infarto do Miocárdio/metabolismo , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismoRESUMO
Males of advanced age represent a rapidly growing population at risk for prostate cancer. In the contemporary setting of earlier detection, a majority of prostate carcinomas are still clinically localized and often treated using radiation therapy. Our recent studies have shown that premature cellular senescence, rather than apoptosis, accounts for most of the clonogenic death induced by clinically relevant doses of irradiation in prostate cancer cells. We show here that this treatment-induced senescence was associated with a significantly increased release of exosome-like microvesicles. In premature senescence, this novel secretory phenotype was dependent on the activation of p53. In addition, the release of exosome-like microvesicles also increased during proliferative senescence in normal human diploid fibroblasts. These data support the hypothesis that senescence, initiated either by telomere attrition (e.g., aging) or DNA damage (e.g., radiotherapy), may induce a p53-dependent increase in the biogenesis of exosome-like vesicles. Ultrastructural analysis and RNA interference-mediated knockdown of Tsg101 provided significant evidence that the additional exosomes released by prematurely senescent prostate cancer cells were principally derived from multivesicular endosomes. Moreover, these exosomes were enriched in B7-H3 protein, a recently identified diagnostic marker for prostate cancer, and an abundance of what has recently been termed "exosomal shuttle RNA." Our findings are consistent with the proposal that exosomes can transfer cargos, with both immunoregulatory potential and genetic information, between cells through a novel mechanism that may be recruited to increase exosome release during accelerated and replicative cellular senescence.
Assuntos
Carcinoma/metabolismo , Senescência Celular/fisiologia , Neoplasias da Próstata/metabolismo , Vesículas Secretórias/metabolismo , Carcinoma/patologia , Endossomos/metabolismo , Endossomos/efeitos da radiação , Exocitose/fisiologia , Humanos , Masculino , Neoplasias da Próstata/patologia , Vesículas Secretórias/efeitos da radiação , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/fisiologiaRESUMO
Tight junctions (TJ) constitute paracellular diffusion channels regulating the passage of ions and solutes across epithelia. We recently demonstrated that overexpression of the TJ membrane protein claudin-7 in LLC-PK1 cells decreases paracellular permeability to Cl(-) and increases paracellular permeability to Na(+). To investigate the effect of charged amino acid residues in extracellular domains (ED) of claudin-7 on paracellular charge selectivity, we created claudin-7 mutants by replacing negatively charged amino acids on ED with positively charged amino acids. Immunofluorescence light microscopy showed that these mutant proteins were correctly targeted to the cell junction. Ultrastructure examination of TJ morphology did not reveal any difference between cells expressing wildtype (WT) and mutant claudin-7. However, electrophysiological studies showed increased Cl(-) permeability in cells expressing first extracellular domain (ED1) mutants, but not second extracellular domain (ED2) mutants, compared to that of WT claudin-7. Our results demonstrate that negatively charged amino acids in ED1 of claudin-7 are involved in modulating paracellular Cl(-) permeability.
Assuntos
Permeabilidade da Membrana Celular/fisiologia , Cloro/metabolismo , Células Epiteliais/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Junções Íntimas/metabolismo , Animais , Linhagem Celular , Claudinas , Líquido Extracelular/química , Líquido Extracelular/metabolismo , Estrutura Terciária de Proteína , Eletricidade Estática , Relação Estrutura-Atividade , SuínosRESUMO
A homologous hamster relaxin RIA was developed to evaluate plasma and tissue concentrations of relaxin in the latter half of pregnancy in this species. Relaxin protein and mRNA were localized using antibodies developed to synthetic hamster relaxin and gene-specific molecular probes, respectively. Molecular weight and isoelectric point of the synthetic and native hormones were identical by electrophoretic methods, and synthetic hamster relaxin was active in the mouse interpubic ligament bioassay. Synthetic hormone was used as tracer and standard with rabbit antiserum to the synthetic hormone in the RIA. Relaxin was assayed in blood samples recovered from the retro-orbital plexus on Days 6, 8, 10, 12, 14, 15, and 16 of gestation and on Days 1 and 5 postpartum. Relaxin was first detected on Day 8 of gestation (3.7 +/- 0.6 ng/ml), increased to reach a maximum in the evening of Day 15 (826.0 +/- 124.0 ng/ml), and decreased by Day 16 (day of parturition). Relaxin concentrations were assayed in aqueous extracts of implantation sites (Days 6, 8, and 10) and chorioallantoic placentae (Days 12, 14, and 15). Concentrations were low on Day 6 (0.02 +/- 0.001 microg/g tissue), increased to Day 15 (6.96 +/- 0.86 microg/g tissue), and subsequently declined by the evening of Day 15. Relaxin protein and mRNA were localized to primary and secondary giant trophoblast cells in the chorioallantoic placental trophospongium. However, relaxin protein was not localized in ovaries of pregnant animals or oviductal tissues of cycling animals. Significant quantities of relaxin were detected in the serum of fetal hamsters recovered on Day 15.