Expression and signalling characteristics of the corticotrophin-releasing hormone receptors during the implantation phase in the human endometrium

Transcriptome Sequencing-Based Mining of Genes Associated With Pubertal Initiation in Dolang Sheep

Improving the fertility of sheep is an important goal in sheep breeding as it greatly increases the productivity. Dolang sheep is a typical representative breed of lamb in Xinjiang and is the main local sheep breed and meat source in the region. To explore the genes associated with the initiation of puberty in Dolang sheep, the hypothalamic tissues of Dolang sheep prepubertal, pubertal, and postpubertal periods were collected for RNA-seq analysis on the Illumina platform, generating 64.08 Gb clean reads. A total of 575, 166, and 648 differentially expressed genes (DEGs) were detected in prepuberty_vs._puberty, postpuberty_vs._prepuberty, and postpuberty_vs._puberty analyses, respectively. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, the related genes involved in the initiation of puberty in Dolang sheep were mined. Ten genes that have direct or indirect functions in the initiation of puberty in Dolang sheep were screened using the GO and KEGG results. Additionally, quantitative real-time PCR was used to verify the reliability of the RNA-Seq data. This study provided a new approach for revealing the mechanism of puberty initiation in sheep and provided a theoretical basis and candidate genes for the breeding of early-pubertal sheep by molecular techniques, and at the same time, it is also beneficial for the protection, development, and utilization of the fine genetic resources of Xinjiang local sheep.

Placental pathology, corticotropin-releasing hormone, timing of parturition, and fetal growth in the pregnancy outcomes and community health study

Background: Identification of vascular pathologies in delivered placentas and their associations with biomarkers measured during pregnancy may elucidate mechanisms of adverse pregnancy outcomes and inform early detection and intervention strategies.Objectives: To examine associations of placental vascular pathology with birth size and timing of parturition, and to evaluate maternal midpregnancy serum corticotropin-releasing hormone (CRH) levels as a marker of the above associations.Study design: The pregnancy outcomes and community health (POUCH) Study enrolled women at 16-27 weeks of pregnancy from five Michigan communities. Histological assessments of delivered placentas and assays of CRH in maternal blood sampled at enrollment were performed in a subcohort of 1152 participants. Five placental vascular pathology constructs were formulated: Maternal-Vascular-Obstructive (MVO), Fetal Vascular-Obstructive (FVO), Maternal Vascular-disturbance of Integrity (MVI), Fetal Vascular-disturbance of Integrity (FVI), and Maternal Vascular-Developmental (MVD). A four-level outcome variable combined small for gestational (SGA) yes/no and delivery timing preterm/term; the non-SGA/term served as the referent group. In multinomial logistic regression models, the five vascular pathology groups were evaluated in relation to the outcome variable and effect sizes were compared before versus after exclusion of participants with high CRH (top quartile).Results: Adjusted odds ratios (aOR) for MVO among SGA/term and SGA/preterm were 4.1 (95% CI: 2.2, 7.9) and 8.8 (95% CI: 3.3, 23.5) respectively. Among SGA/preterm births, the aOR was attenuated by ∼40%, i.e. 5.4 (95% CI: 1.1, 26.2) after removing high CRH pregnancies. MVI and FVO were each associated with SGA/preterm, aOR = 3.7 (95% CI: 1.3, 10.3) and 10.5 (95% CI: 3.6, 30.8) respectively. Removal of high CRH pregnancies reduced the OR estimates by nearly half, i.e. MVI aOR = 1.9 (95% CI: 0.34, 10.9), FVO aOR = 6.0 (95% CI: 1.3, 28.6). MVI, FVI and MVD were each associated with greater odds of non-SGA/preterm, but the aORs showed little change after removing high CRH pregnancies.Conclusions: Obstructive placental vascular pathologies in maternal or fetal vessels are associated with SGA. High CRH levels coincided with a portion of pregnancies that share these complications, particularly among pregnancies that also ended prematurely.

Effects of dorsal periaqueductal gray CRF1- and CRF2-receptor stimulation in animal models of panic

An increasing amount of evidence suggests that dysregulation of corticotrophin-releasing factor (CRF) signaling may contribute to the etiology of anxiety disorders such as post-traumatic stress disorder and panic. The dorsal periaqueductal gray matter (dPAG) in the midbrain has been considered a key region involved in the physiopathology of anxiety and panic. Administration of CRF in this structure enhances the expression of anxiety-related defensive behaviors in different animal models. Controversial results have been obtained regarding the involvement of CRF1 and CRF2 receptors in the regulation of panic-related responses. We report here that CRF (0.0625-1 μg) in the dPAG facilitates escape expression in two animal models that associate this behavior with panic, the elevated T-maze and the electrical stimulation of the dPAG. This effect, equally observed after CRF injection in the dorsomedial and dorsolateral columns of the PAG, is due to the activation of CRF1 receptors as revealed by its blockade by the CRF1 receptor antagonist antalarmin. In the elevated T-maze, CRF also facilitates inhibitory avoidance acquisition, suggesting an anxiogenic effect. Local administration of urocortin 2 (0.01-0.1 μg), a preferential CRF2 receptor agonist, failed to change escape expression, but impaired avoidance learning, indicating an anxiolytic effect. The results indicate that CRF1 receptors in the dPAG play a pervasive role in the regulation of defensive responses associated with both generalized anxiety and panic. Recruitment of CRF2 receptors only impacts upon the former type of behaviors, leading to an effect opposed to that caused by CRF1 receptor activation.

Expression of corticotrophin-releasing hormone and its receptor in patients with intrahepatic cholestasis of pregnancy

OBJECTIVE

Intrahepatic cholestasis of pregnancy (ICP) is the most common pregnancy-specific liver disorders. Although various biological effects of corticotrophin-releasing hormone (CRH) has in pregnancy have been reported, its activities in patients with ICP are lacking. Here we evaluated CRH and its receptor (CRH-R1) expression in placenta and serum in control and ICP patients, to assess their potential activities in the ICP pathogenesis.

METHODS AND MATERIALS

Placental tissues were obtained from the control and ICP patients (10 cases for each group) between 37 and 39 gestational weeks. Immunohistochemistry, Western Blotting and real-time PCR analysis were used to detect the CRH and CRH-R1 expression in placenta. Meanwhile, maternal serums were analyzed for detecting CRH in the control and ICP patients (80 cases for each group) in 34-37 gestational weeks. All data were observed and recorded for comparing and analyzing in control and ICP patients.

RESULTS

CRH staining was found in syncytiotrophoblast and feto-placental vascular endothelium cells of placenta, whereas CRH-R1 staining was found in syncytiotrophoblast by using immunohistochemical analysis. The CRH expression level in ICP placenta was significantly lower than those results in controls (P < 0.01). For CRH-R1, CRH mRNA and CRH-R1 mRNA expressions, no statistical differences were found between control and ICP groups (all P > 0.05). Serum CRH levels increased in both control and ICP groups, but the growth rate was limited in ICP group, especially in late pregnancy (P < 0.05).

CONCLUSIONS

The down-regulation of CRH in ICP placentas and the limited growth rate of CRH in the maternal serum of ICP patients might impair the blood flow regulation of the utero-placental-fetal unit, which might result in poor fetoplacental vascular perfusion and adverse pregnancy outcomes. CRH might play a significant role in the pathogenesis of ICP and provide a new approach to further investigate the etiology of ICP.

Physical therapy and psychological intervention normalize cortisol levels and improve vitality in women with endometriosis

There is as yet no effective treatment for endometriosis. The objective of this study was to evaluate the effectiveness of submitting women with endometriosis and chronic pelvic pain to a therapeutic protocol involving physical and psychological therapy. Twenty-six female volunteers were submitted to a treatment protocol consisting of 2.5-h sessions, once a week for 10 weeks. We applied a Visual Analogue Scale, the Perceived Stress Questionnaire (PSQ), and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36). Morning, afternoon, and evening levels of cortisol were determined in saliva samples. The PSQ scores were significantly lower after treatment, whereas the scores for the SF-36 vitality and physical functioning domains were significantly higher. Salivary cortisol levels were higher after treatment in the samples collected in the morning, but not in those collected in the afternoon or evening. The post-treatment cortisol levels were similar to those reported for healthy women. There were positive correlations between vitality, role emotional, social functioning, and mental health, and negative correlations to perceived stress. In conclusion, the physical and psychological intervention protocol applied in this study to women suffering of endometriosis was effective in reducing perceived stress, normalizing cortisol levels, increasing vitality and improving physical functioning.

Mapping structural determinants within third intracellular loop that direct signaling specificity of type 1 corticotropin-releasing hormone receptor

The type 1 corticotropin-releasing hormone receptor (CRH-R1) influences biological responses important for adaptation to stressful stimuli, through activation of multiple downstream effectors. The structural motifs within CRH-R1 that mediate G protein activation and signaling selectivity are unknown. The aim of this study was to gain insights about important structural determinants within the third intracellular loop (IC3) of the human CRH-R1α important for cAMP and ERK1/2 pathways activation and selectivity. We investigated the role of the juxtamembrane regions of IC3 by mutating amino acid cassettes or specific residues to alanine. Although simultaneous tandem alanine mutations of both juxtamembrane regions Arg²⁹²-Met²⁹⁵ and Lys³¹¹-Lys³¹⁴ reduced ligand binding and impaired signaling, all other mutant receptors retained high affinity binding, indistinguishable from wild-type receptor. Agonist-activated receptors with tandem mutations at the proximal or distal terminal segments enhanced activation of adenylyl cyclase by 50–75% and diminished activation of inositol trisphosphate and ERK1/2 by 60–80%. Single Ala mutations identified Arg²⁹², Lys²⁹⁷, Arg³¹⁰, Lys³¹¹, and Lys³¹⁴ as important residues for the enhanced activation of adenylyl cyclase, partly due to reduced inhibition of adenylyl cyclase activity by pertussis toxin-sensitive G proteins. In contrast, mutation of Arg²⁹⁹ reduced receptor signaling activity and cAMP response. Basic as well as aliphatic amino acids within both juxtamembrane regions were identified as important for ERK1/2 phosphorylation through activation of pertussis toxin-sensitive G proteins as well as G_q proteins. These data uncovered unexpected roles for key amino acids within the highly conserved hydrophobic N- and C-terminal microdomains of IC3 in the coordination of CRH-R1 signaling activity.

Expression of CRH, CRH-related peptide and CRH receptor in the ovary and potential CRH signalling pathways

Capacity to cope with stress is crucial for survival and also reproduction. The stress response differs in the various parts of an organism. Central corticotropin-releasing hormone (CRH) has been identified to be the main stress regulator. In the reproductive system, stress has a deleterious effect on reproduction and CRH is associated with dysfunction of the reproductive endocrine axis. Members of the CRH family have been detected in different reproductive organs of males and females. Ovarian CRH is probably involved in steroid biosynthesis and inflammatory like processes, ovulation and luteolysis. These effects are mediated via the CRH receptors CRH-R1 and CRH-R2. CRH-Rs are G protein-coupled receptors that drive different signalling pathways in the cell. In human, ligands for these receptors are CRH, urocortin 1, stresscopin-related peptide and stresscopin. This review gives an overview on the expression of the CRH family members in the ovary of mammals. Furthermore, potential CRH-induced signalling mechanisms in the ovary will be introduced.

Urocortin 2 and urocortin 3 in endometriosis: evidence for a possible role in inflammatory response

Urocortin 2 (Ucn 2) and urocortin 3 (Ucn 3) are neuropeptides expressed by human endometrium. This study evaluated (i) the expression of Ucn 2 and Ucn 3 mRNA in endometriotic lesions and in endometrium of women with endometriosis; (ii) the effect of Ucn 2 and Ucn 3 on cytokines secretion from cultured endometrial stromal cells. Endometriotic tissue was collected from endometrioma (n=39); endometrial specimens were obtained from women with (n=39) and without (n=41) endometriosis throughout menstrual cycle. Tissue specimens were analysed for Ucn 2 and Ucn 3 mRNA expression and peptide localization; the effects of Ucn 2 or Ucn 3 on tumour necrosis factor (TNF-α) and interleukin (IL-4) secretion from cultured endometrial stromal cells was studied. Ucn 2 and Ucn 3 mRNA expression and localization were assessed by RT-PCR and by immuohistochemistry, respectively; cytokines secretion were measured by ELISA. Results showed that endometriotic tissue expressed both Ucn 2 and Ucn 3, with Ucn 3 expression higher in ectopic than in eutopic endometrium. Endometrial Ucn 2 mRNA expression in controls showed peak values at early proliferative phase, while in endometriotic patients low expression and no significant changes throughout menstrual cycle were observed. Endometrial Ucn 3 mRNA expression was highest in late secretory phase in controls, while in endometriotic patients low levels and no menstrual-cycle-related changes were found. When added to cultured endometrial cell cultures, Ucn 2 significantly increased TNF-α (P<0.01) and IL-4 (P<0.001), while Ucn 3 induced an increase of IL-4 secretion (P<0.01). In conclusion, endometriotic tissue expressed and localized Ucn 2 and Ucn 3; patients with endometriosis showed Ucn 2 and Ucn 3 mRNA expression in eutopic endometrium lower than in control group, with no endometrial cycle-related changes. Ucn 2 and Ucn 3-modulated TNF-α and IL-4 secretion from culture endometrial cells. These data suggest a possible involvement of Ucn 2 and Ucn 3 in the mechanisms of endometriosis.

Attenuated tubal and endometrial urocortin 1 and corticotropin-releasing hormone receptor expression in ectopic pregnancy

Fallopian tube (FT) and endometrial urocortin 1 (Ucn1) and corticotropin-releasing hormone (CRH)-receptor (CRH-R1/CRH-R2) expression were examined using quantitative real-time polymerase chain reaction (RT-PCR) and immunohistochemistry in nonpregnant and pregnant women (intrauterine, IUP; ectopic pregnancy, EP). Tubal Ucn1 messenger RNA (mRNA) expression was higher in luteal compared to follicular phase (P < .01) and equivalent to follicular phase in FT from EP. Tubal CRH-R1/CRH-R2 mRNA was lower in luteal phase (P < .05) and in FT from EP compared to follicular phase (P < .01). Ucn1 mRNA was lower in endometrium from EP compared to IUP (P < .05). Corticotropin-releasing hormone-R1 mRNA was higher in endometrium from EP compared to viable IUP (P < .05). No differences were observed in CRH-R2 expression. Corticotropin-releasing hormone-R1 protein was primarily localized to epithelium of FT and endometrium. Quantitative analysis of tubal CRH-R1 protein expression reflected that seen at the mRNA level but endometrial expression was equivocal. The demonstration of attenuated tubal/endometrial Ucn1/CRH-R expression in EP further supports a role of the CRH-family in embryo implantation.

Levels of maternal serum corticotropin-releasing hormone (CRH) at midpregnancy in relation to maternal characteristics

BACKGROUND

Corticotropin-releasing hormone (CRH) in maternal blood originates primarily from gestational tissues and elevated levels in midpregnancy have been linked to adverse pregnancy outcomes. Investigators have hypothesized that high levels of maternal stress might lead to elevated CRH levels in pregnancy. Yet a few studies have measured maternal CRH levels among subgroups of women who experience disproportionate socioeconomic disadvantage, such as African-American and Hispanic women, and found that these groups have lower CRH levels in pregnancy. Our goal was to identify maternal characteristics related to CRH levels in midpregnancy and examine which if any of these factors help to explain race differences in CRH levels.

METHODS

The Pregnancy Outcomes and Community Health (POUCH) Study prospectively enrolled women at 15-27 weeks' gestation from 52 clinics in five Michigan communities (1998-2004). Data from the POUCH Study were used to examine maternal demographics, anthropometrics, health behaviors, and psychosocial factors (independent variables) in relation to midpregnancy blood CRH levels modeled as logCRHpg/ml (dependent variable). Analyses were conducted within a sub-cohort from the POUCH Study (671 non-Hispanic Whites, 545 African-Americans) and repeated in the sub-cohort subset with uncomplicated pregnancies (n=746). Blood levels of CRH and independent variables were ascertained at the time of enrollment. All regression models included week of enrollment as a covariate. In addition, final multivariate regression models alternately incorporated different psychosocial measures along with maternal demographics and weight. Psychosocial variables included measures of current depressive symptoms, perceived stress, coping style, hostility, mastery, anomie, and a chronic stressor (history of abuse as a child and adult).

RESULTS

In sub-cohort models, the adjusted mean log CRH level was significantly lower in African-Americans vs. non-Hispanic Whites; the difference was -0.48pg/ml (P<0.01). This difference was reduced by 21% (-0.38pg/ml, P<0.01) after inclusion of other relevant covariates. Adjusted mean log CRH levels were also lower among women with <12 years vs. >or=12 years of education (minimal difference=-0.19pg/ml, P<0.05), and among women with high levels of depressive symptoms who did not use antidepressants vs. women with lower levels of depressive symptoms and no antidepressant use (minimal difference=-0.13pg/ml, P<0.01). Log CRH levels were inversely associated with maternal weight (-0.03pg/ml per 10 pound increase, P<.05) but unrelated to smoking and all other psychosocial measures. Results were similar in the subset of women with uncomplicated pregnancies, except that lower CRH levels were also linked to higher perceived stress.

CONCLUSION

African-American women have lower blood CRH levels at midpregnancy and the race difference in CRH levels is reduced modestly after adjustment for other maternal characteristics. CRH levels were not elevated among women with high levels of perceived stress or more chronic stressors. The inverse association between CRH levels and maternal weight is likely due to a hemodilution effect. Relations among maternal CRH levels and maternal race, educational level, and depressive symptoms are difficult to explain and invite further investigation. Our results highlight a group of covariates that merit consideration in studies that address CRH in the context of pregnancy and/or post-partum complications.

Possible actions of corticotropin-releasing hormone in regulating porcine corpus luteum function

The objective of the present study was to determine whether corticotropin-releasing hormone (CRH) influences porcine corpus luteum function. The gene expressions of CRH receptors (CRH-R) were determined in the CLs of Chinese Meishan pigs during the estrous cycle. The effects of CRH on progesterone (P), estradiol-17β (E) and prostaglandin (PG) F(2α) secretion by cultured luteal cells were also investigated. Messenger RNAs of the CRH-R were clearly expressed in the CL throughout the estrous cycle, and the mRNA level was higher at the regressed stage than at the other stages (P<0.05). When the cultured luteal cells obtained from the mid-luteal stage CL (days 8-11) were exposed to CRH (50-5000 ng/ml), P secretion by the cells was significantly reduced at the highest dose (P<0.05), whereas CRH had no effect on E and PGF(2α) secretion by the cells. The overall results suggest that CRH inhibits local P production from luteal cells via its specific CRH-R, implying that CRH plays some roles in regulating porcine CL function during the estrous cycle, especially in the period of luteolysis.

Expression and subcellular localization of CRH and its receptors in human endometrial cancer

CRH and its receptors are expressed in human normal endometrial cells, where they are associated to anti-proliferative progesterone-like activity. We aimed to investigate CRH, CRH-R1 and CRH-R2 expression and intracellular localization in human endometrial cancers and their relationships with tumor biological parameters. Surgical specimens were obtained from 51 untreated endometrial cancer patients and immunohistochemistry for CRH, CRH receptors, ER, PR and Ki-67 was performed. We found a diffuse cytoplasmic staining in 100%, 92 % and 60.7 % of tumor specimens for CRH, CRH-R1 and CRH-R2, respectively. At variance with tumor tissues, the surrounding normal endometrial glands exhibit a typical paranuclear/apical pattern for CRH and stained for CRH-R2 at the nuclear level, whereas CRH-R1 staining was similar to that observed in tumor area. Positive correlations were found between CRH-R1 and PR expression, as well as between CRH-R2 cytoplasmic pattern and more advanced FIGO stage disease, respectively.

Reduced expression of CRH receptor type 1 in upper segment human myometrium during labour

BACKGROUND

Corticotropin-releasing hormone (CRH) and CRH-related peptide are shown to modulate uterine contractility through two CRH receptor subtype, CRH-R1 and CRH-R2 during pregnancy. Through different signaling pathways, CRH-R1 maintains myometrial quiescence whereas CRH-R2 promotes smooth muscle contractility. We hypothesized that the expression of CRH receptors in myometrium might be changed during pregnancy and labour.

METHOD

Immunohistochemistry, Western blot and RT-PCR were used to quantify the cellular localization, the protein levels and the mRNA variants of both CRH-R1 and CRH-R2 in upper segment (US) and lower segment (LS) myometrium from nonpregnant and pregnant women at term before or after labour.

RESULTS

CRH-R1 and CRH-R2 were predominately localized to myometrial smooth muscle cells in US and LS. The protein level of CRH-R1 in US was significantly down-regulated in pregnancy, with a further decrease at the onset of labour. However, the expression of CRH-R1 in LS remained unchanged during pregnancy and labour. No significant changes in CRH-R2 expression were observed in US or LS. Six variants of CRH-R1, CRH-R1alpha,-R1beta,-R1c, -R1e,-R1f and -R1g, were identified in nonpregnant and pregnant myometrium. CRH-R2alpha was identified in pregnant myometrium, whereas CRH-R2beta was identified in nonpregnant myometrium

CONCLUSION

CRH-R1 and CRH-R2 are expressed in nonpregnant and pregnant US and LS myometrium. Changed expression of CRH receptors during labour may underlie the initiation of uterine contractility during parturition.

Expression of corticotropin-releasing hormone receptor type 1 and type 2 in human pregnant myometrium

It has been suggested that corticotropin-releasing hormone (CRH) receptors CRH-R1 and CRH-R2 might be involved in the modulation of uterine activity during pregnancy. The authors determine the localization, concentrations, and variants of CRH-R1 and CRH-R2 in the human pregnant myometrium from patients undergoing labor and patients not undergoing labor. Biopsies were taken from 40 patients undergoing either elective or emergency cesarean delivery after spontaneous labor. The localization of CRH-R1 and CRH-R2 was examined by immunohistochemistry. The mRNA and protein levels of CRH-R1 and CRH-R2 were measured by quantitative reverse-transcriptase polymerase chain reaction (PCR) and Western blot analysis, respectively. The variants of CRH-R1 and CRH-R2 were determined by PCR analysis followed by sequencing. Both CRH-R1 and CRH-R2 were found by immunohistochemistry to be expressed by smooth muscle cells in the pregnant myometrium. There was no significant difference in mRNA and protein levels of CRH-R1 and CRH-R2 in myometria between the labor and nonlabor groups. Levels of CRH-R1 alpha , R1 beta, R1c, R1e, R1f, and R2 alpha were identified in the pregnant myometrium, and levels of CRH-R1 alpha, R1c, and R2 alpha were detected in both the term labor and nonlabor myometrium. A heterogeneous distribution of other CRH-R1 variants in term labor and nonlabor myometrium was observed. Human myometrium expresses both CRH-R1 and CRH-R2 during pregnancy. A heterogeneous distribution of CRH-R1 variants in term labor and nonlabor myometrium might be related to the effects of CRH on contractile phenotype of myometrium at the term.

Structural domains determining signalling characteristics of the CRH-receptor type 1 variant R1beta and response to PKC phosphorylation

Mammalian adaptive mechanisms to stressful stimuli involve release of corticotropin-releasing hormone (CRH) and downstream activation of specific G-protein-coupled 7 transmembrane domain receptors. These CRH receptors (CRH-R) are expressed as multiple mRNA spliced variants. In contrast to other mammals, the human type 1 CRH-R gene contains an additional exon (exon 6) that needs to be spliced out in order to generate the fully active CRH-R1alpha. Transcription of all 14 exons results in a CRH-R1 variant (CRH-R1beta) with an extended 1st intracellular loop (IC1); this sequence modification impairs signalling activity and alters receptor responsiveness to PKC-induced phosphorylation that leads to signalling desensitization and receptor endocytosis. To elucidate structure-function relationships and delineate sequences involved in CRH-R1beta properties, site directed mutagenesis was used to introduce a number of specific mutations into IC1 of CRH-R1beta as well as replace specific phospho-acceptor residues within the aminoacid sequence of CRH-R1alpha and CRH-R1beta. Mutant receptors were transiently expressed in human embryonic kidney (HEK293) cells and tested for their abilities to increase intracellular cAMP and their response to PKC-induced phosphorylation. Results identified a penta-aminoacid cassette within the 29-aminoacid insert of CRH-R1beta, which contains multiple positive charged aminoacids (F170-R174), as an important structural determinant for the impaired cAMP response. Furthermore, serine at position 408 in the carboxy-terminus appears to be important for mediating CRH-R1alpha resistance, but not CRH-R1beta susceptibility, to PKC-induced desensitization and internalization. These findings provide new insights about the structural determinants of CRH-R1 coupling to Gs proteins and response to protein kinase phosphorylation.

Corticotropin-releasing hormone receptor type 1 and type 2 mediate differential effects on 15-hydroxy prostaglandin dehydrogenase expression in cultured human chorion trophoblasts

Throughout gestation, the chorion laeve controls the levels of biologically active prostaglandins (PGs) by its high level of nicotinamide adenine dinucleotide-dependent 15-hydroxy PG dehydrogenase (PGDH). In this study, we investigate the effects mediated by CRH receptors on the expression of PGDH in the chorion. We found that both CRHR1 and CRHR2 were localized in cultured chorion trophoblast cells, with CRH-R1alpha, R1beta, R1c, R1e, and R1f and CRHR2beta isoforms identified in these cells. To block the actions of endogenous CRH and its related peptides, cultured chorion trophoblasts were treated with an increasing concentration of alpha-helical CRH 9-41, the nonselective CRH receptor antagonist, which resulted in decreased mRNA and protein expression as well as the activity of PGDH. To investigate the individual role of CRHR1 and CRHR2, cell cultures were treated with the specific CRHR1 antagonist antalarmin and CRHR2 antagonist astressin2B, respectively. The results showed that antalarmin increased whereas astressin2B decreased mRNA and protein expression as well as the activity of PGDH in chorion cells. When the cells were treated with an exclusive CRHR2 agonist, urocortin II, elevated expression and activity of PGDH was exhibited. However, cells treated with either exogenous CRH or urocortin I showed significantly increased PGDH expression, and these effects could be blocked by astressin2B but not by antalarmin. We suggest that, in chorion trophoblast cells, CRHR1 and CRHR2 mediate divergent effects on PGDH expression, and this may provide a precise regulation of PGs levels from chorion to myometrium during pregnancy.

Human endometrium expresses urocortin II and III messenger RNA and peptides

Urocortin II and urocortin III are recently identified corticotropin-releasing factor-related neuropeptides, and their endometrial expression throughout the menstrual cycle and in early pregnancy was evaluated in the present study by semiquantitative reverse transcriptase polymerase chain reaction and immunohistochemistry. The endometrial expression of urocortin II mRNA was significantly (P<.01) higher in the early proliferative phase of the menstrual cycle than in other phases and maternal decidua (MD), whereas that of urocortin III mRNA was higher (P<.01) in MD than in all other endometrial samples. Both peptides were immunolocalized in epithelial, stromal, and endothelial cells.

Differential responses of corticotropin-releasing hormone receptor type 1 variants to protein kinase C phosphorylation

Corticotropin-releasing hormone (CRH) regulates diverse biological functions in mammals, through activation of two types of specific G protein-coupled receptors that are expressed as multiple mRNA spliced variants. In most cells, the type 1alpha CRH receptor (CRH-R1alpha) preferentially activates the G(s)-adenylyl cyclase signaling cascade. CRH-R1alpha-mediated signaling activity is impaired by insertion of 29 amino acids in the first intracellular loop, a sequence modification that is characteristic of the human-specific CRH-R1beta variant. In various tissues, CRH signaling events are regulated by protein kinase C (PKC). The CRH receptors contain multiple putative PKC phosphorylation sites that represent potential targets. To investigate this, we expressed recombinant CRH-R1alpha or CRH-R1beta in human embryonic kidney 293 cells and analyzed signaling events after PKC activation. Agonist (oxytocin) or phorbol 12-myristate 13-acetate-induced activation of PKC led to phosphorylation of both CRH-R1 variants. However, CRH-R1alpha and CRH-R1beta exhibited different functional responses to PKC-induced phosphorylation, with only the CRH-R1beta susceptible to cAMP signaling desensitization. This was associated with a significant decrease of accessible CRH-R1beta receptors expressed on the cell surface. Both CRH-R1 variants were susceptible to homologous desensitization and internalization following treatment with CRH; however, PKC activation increased internalization of CRH-R1beta but not CRH-R1alpha in a beta-arrestin-independent manner. Our findings indicate that CRH-R1alpha and -R1beta exhibit differential responses to PKC-induced phosphorylation, and this might represent an important mechanism for functional regulation of CRH signaling in target cells.

Secretory endometrium highly expresses urocortin messenger RNA and peptide: possible role in the decidualization process

BACKGROUND

Urocortin (UCN) gene expression and synthesis have been reported in epithelial and stromal cells of the human endometrium. In this study we evaluated (i) UCN messenger RNA (mRNA) expression and peptide production in uterine specimens collected throughout the endometrial cycle, (ii) UCN secretion after decidualization of cultured human endometrial stromal cells (HESCs) and (iii) the effect of UCN on endometrial decidualization.

METHODS

HESCs were isolated from samples of human endometrium collected from healthy patients with normal menstrual cycle and cultured in presence of cAMP, 17-beta-estradiol (E(2)) + medroxyprogesterone acetate (MPA) and UCN. UCN levels were measured in endometrial extracts by an enzyme immunoassay, and changes of endometrial UCN mRNA expression were measured by RT-PCR analysis.

RESULTS

UCN peptide concentrations and mRNA expression were highest in the secretory phase of the menstrual cycle (P < 0.001, late secretory versus early and late proliferative phase) and higher in the late than the early secretory phase (P < 0.01). After decidualization of HESC with cAMP or E(2) + MPA, UCN levels rose in parallel with prolactin concentrations by days 6 (P < 0.01, for all). Finally, the addition of UCN to HESCs, with or without E(2) + MPA, induced the release of prolactin.

CONCLUSIONS

The evidence that (i) UCN is highly expressed in the secretory phase of the endometrial cycle; (ii) cAMP and E(2) + MPA modulate secretion of UCN and (iii) UCN induces HESCs decidualization together suggest a possible role for UCN in endometrial physiology.

Corticotropin releasing factor (CRF) receptor signaling in the central nervous system: new molecular targets

Corticotropin-releasing factor (CRF) and the related urocortin peptides mediate behavioral, cognitive, autonomic, neuroendocrine and immunologic responses to aversive stimuli by activating CRF(1) or CRF(2) receptors in the central nervous system and anterior pituitary. Markers of hyperactive central CRF systems, including CRF hypersecretion and abnormal hypothalamic-pituitary-adrenal axis functioning, have been identified in subpopulations of patients with anxiety, stress and depressive disorders. Because CRF receptors are rapidly desensitized in the presence of high agonist concentrations, CRF hypersecretion alone may be insufficient to account for the enhanced CRF neurotransmission observed in these patients. Concomitant dysregulation of mechanisms stringently controlling magnitude and duration of CRF receptor signaling also may contribute to this phenomenon. While it is well established that the CRF(1) receptor mediates many anxiety- and depression-like behaviors as well as HPA axis stress responses, CRF(2) receptor functions are not well understood at present. One hypothesis holds that CRF(1) receptor activation initiates fear and anxiety-like responses, while CRF(2) receptor activation re-establishes homeostasis by counteracting the aversive effects of CRF(1) receptor signaling. An alternative hypothesis posits that CRF(1) and CRF(2) receptors contribute to opposite defensive modes, with CRF(1) receptors mediating active defensive responses triggered by escapable stressors, and CRF(2) receptors mediating anxiety- and depression-like responses induced by inescapable, uncontrollable stressors. CRF(1) receptor antagonists are being developed as novel treatments for affective and stress disorders. If it is confirmed that the CRF(2) receptor contributes importantly to anxiety and depression, the development of small molecule CRF(2) receptor antagonists would be therapeutically useful.

Differential expression of mouse orexin receptor type-2 (OX2R) variants in the mouse brain

We have identified two novel mouse orexin type-2 receptor (OX2R) splice variants: OX2alphaR and OX2betaR. Here, we have mapped in detail the differential gene expression of OX2alphaR and OX2betaR in the mouse brain. Using RT-PCR and in situ hybridization, we show that OX2alphaR is expressed in various areas of the mouse brain and has low expression in caudal part of cerebellum. OX2betaR is expressed in detectable levels, with the exception of striatum, midbrain and anterior part of cerebellum/pons. Our novel findings demonstrate the differential expression of OX2R splice variants in the mouse brain.

The molecular mechanisms underlying the regulation of the biological activity of corticotropin-releasing hormone receptors: implications for physiology and pathophysiology

The CRH receptor (CRH-R) is a member of the secretin family of G protein-coupled receptors. Wide expression of CRH-Rs in the central nervous system and periphery ensures that their cognate agonists, the family of CRH-like peptides, are capable of exerting a wide spectrum of actions that underpin their critical role in integrating the stress response and coordinating the activity of fundamental physiological functions, such as the regulation of the cardiovascular system, energy balance, and homeostasis. Two types of mammal CRH-R exist, CRH-R1 and CRH-R2, each with unique splicing patterns and remarkably distinct pharmacological properties, but similar signaling properties, probably reflecting their distinct and sometimes contrasting biological functions. The regulation of CRH-R expression and activity is not fully elucidated, and we only now begin to fully understand the impact on mammalian pathophysiology. The focus of this review is the current and evolving understanding of the molecular mechanisms controlling CRH-R biological activity and functional flexibility. This shows notable tissue-specific characteristics, highlighted by their ability to couple to distinct G proteins and activate tissue-specific signaling cascades. The type of activating agonist, receptor, and target cell appears to play a major role in determining the overall signaling and biological responses in health and disease.

Functions of corticotropin-releasing hormone in anthropoid primates: From brain to placenta

Corticotropin-releasing hormone (CRH) is an ancient regulatory molecule. The CRH hormone family has at least four ligands, two receptors, and a binding protein. Its well-known role in the hypothalamic-pituitary-adrenal (HPA) axis is only one of many. The expression of CRH and its related peptides is widespread in peripheral tissue, with important functions in the immune system, energy metabolism, and female reproduction. For example, CRH is involved in the implantation of fertilized ova and in maternal tolerance to the fetus. An apparently unique adaptation has evolved in anthropoid primates: placental expression of CRH. Placental CRH stimulates the fetal adrenal zone, an adrenal structure unique to primates, to produce dehydroepiandrosterone sulfate (DHEAS), which is converted to estrogen by the placenta. Cortisol induced from the fetal and maternal adrenal glands by placental CRH induces further placental CRH expression, forming a positive feedback system that results in increasing placental production of estrogen. In humans, abnormally high placental expression of CRH is associated with pregnancy complications (e.g., preterm labor, intrauterine growth restriction (IUGR), and preeclampsia). Within anthropoid primates, there are at least two patterns of placental CRH expression over gestation: monkeys differ from great apes (and humans) by having a midgestational peak in CRH expression. The functional significance of these differences between monkeys and apes is not yet understood, but it supports the hypothesis that placental CRH performs multiple roles during gestation. A clearer understanding of the diversity of patterns of placental CRH expression among anthropoid primates would aid our understanding of its role in human pregnancy.

Food deprivation differentially modulates orexin receptor expression and signaling in rat hypothalamus and adrenal cortex

Although starvation-induced biochemical and metabolic changes are perceived by the hypothalamus, the adrenal gland plays a key role in the integration of metabolic activity and energy balance, implicating feeding as a major synchronizer of rhythms in the hypothalamic-pituitary-adrenal (HPA) axis. Given that orexins are involved in regulating food intake and activating the HPA axis, we hypothesized that food deprivation, an acute challenge to the systems that regulate energy balance, should elicit changes in orexin receptor signaling at the hypothalamic and adrenal levels. Food deprivation induced orexin type 1 (OX1R) and 2 (OX2R) receptors at mRNA and protein levels in the hypothalamus, in addition to a fivefold increase in prepro-orexin mRNA. Cleaved peptides OR-A and OR-B are also elevated at the protein level. Interestingly, adrenal OX1R and OX2R levels were significantly reduced in food-deprived animals, whereas there was no expression of prepro-orexin in the adrenal gland in either state. Food deprivation exerted a differential effect on OXR-G protein coupling. In the hypothalamus of food deprived rats compared with controls, a significant increase in coupling of orexin receptors to Gq, Gs, and Go was demonstrated, whereas coupling to Gi was relatively less. However, in the adrenal cortex of the food-deprived animal, there was decreased coupling of orexin receptors to Gs, Go, and Gq and increased coupling to Gi. Subsequent second-messenger studies (cAMP/IP3) have supported these findings. Our data indicate that food deprivation has differential effects on orexin receptor expression and their signaling characteristics at the hypothalamic and adrenocortical levels. These findings suggest orexins as potential metabolic regulators within the HPA axis both centrally and peripherally.

Urinary gonadotrophins but not recombinant gonadotrophins reduce expression of VEGF120 and its receptors flt-1 and flk-1 in the mouse uterus during the peri-implantation period

BACKGROUND

Ovarian stimulation in humans might affect the perinatal outcome and be considered as a stress factor in the implantation process. In this study we compared the effects of recombinant and urinary gonadotrophins during the mouse peri-implantation period.

METHODS

Adult female CD1 mice were treated as follows (a) urinary hFSH and urinary hCG, (b) recombinant hFSH and recombinant hLH and (c) saline. The effects of the gonadotrophins on the expression of vascular endothelial growth factor120 (VEG120) and its receptors and the corticotrophin releasing hormone (CRH) system during the peri-implantation period were studied. The specific effects of the different gonadotrophins on the onset of implantation were also studied.

RESULTS

Urinary gonadotrophin treatment caused lower levels of VEGF120, flt-1 and flk-1 mRNA levels, reduced the size of the embryo implantation site, delayed implantation and prolonged the gestational period. Both urinary hFSH and urinary hCG contributed to the adverse effects. Levels of CRH and CRHR1 expression were not influenced. Recombinant gonadotrophin treatment did not alter any of the parameters studied.

CONCLUSIONS

Our results show that the VEGF system of the mouse uterus during the peri-implantation period is adversely affected by urinary gonadotrophins but not by recombinant gonadotrophins. The CRH system was not affected by the two types of gonadotrophins.

Factors controlling blastocyst implantation

Establishment of early pregnancy is promoted by a complex network of signalling molecules that mediate cell-to-cell and cell-to-extracellular matrix communications, in order to manifest controlled invasion of the trophectoderm and successful implantation. During the period known as the 'window of implantation', the endometrium expresses specialized proteins, many of which exhibit potential use as markers of endometrial receptivity. Trophoblast differentiation to the invasive phenotype also depends on the up-regulation of certain peptides and the down-regulation of others. Disruption of each pathway is theoretically possible, and studies in animal models suggest that implantation defects result when the function of these proteins is blocked. Indeed, the implantation process is currently considered the most important limiting factor for the establishment of viable pregnancy. The present overview of the literature reports critical families of molecules located at the embryo-maternal interface and describes the mechanisms of interplay and control. Since these factors are crucial to the process of implantation, targeting them might be a valuable contraceptive tool. Conversely, induction of specific peptides may prove to be beneficial in certain infertility cases.

Increased Numbers of Activated Mast Cells in Endometriosis Lesions Positive for Corticotropin-Releasing Hormone and Urocortin

PROBLEM

Mast cells are critical in allergic and inflammatory diseases such as interstitial cystitis, which is often clinically associated with or mistaken as endometriosis. Mast cells had previously been reported to be increased at sites of endometriosis, and tryptase may contribute to the fibrosis and inflammation characterizing endometriosis.

METHOD OF STUDY

This is a pilot study of mast cell numbers and its activation in endometriosis biopsies (n = 10) by immunostaining for mast cell tryptase, corticotropin-releasing hormone (CRH) and urocortin (Ucn).

RESULTS

This is the first report that tryptase positive mast cells were not only increased (64-157 mast cells/mm(2)) in human endometriosis, but also highly activated (89%) in areas strongly stained positive for CRH/Ucn. Normal endometrium was weakly positive for both CRH/Ucn.

CONCLUSION

High numbers of activated mast cells are present in endometriosis sites that were strongly positive for CRH/Ucn. CRH and Ucn may activate mast cells and contribute to the fibrosis and inflammation in endometriosis.

Urocortins in human reproduction

Data on biological effects and localization of corticotropin-releasing factor (CRF), a neuropeptide structurally and biologically related to urocortins, have triggered the study on expression of urocortins and their function in human reproductive tissues. Ovary, endometrium, placenta and fetal membranes (amnion and chorion), myometrium, and prostate are sources of urocortin 1 and, they also express urocortin binding sites (receptors and CRF-binding protein), thus suggesting that these tissues are also targets of urocortin 1. The current concept thus is that urocortin 1 may affect the physiology of human reproduction through paracrine/autocrine actions. In particular, in vitro data have shown that urocortin 1 plays a major role in human placenta: it stimulates the secretion of ACTH, prostaglandins and activin A from cultured human placental cells, and regulates placental vessel resistance to blood flow. Furthermore, when incubated in myometrial strips, urocortins stimulate uterine contractility, by activating specific intracellular pathways. Taken together, these findings do suggest an important role of urocortins in the physiology of pregnancy and parturition.