The functional significance of the endometrial hCG/ LH receptors has been related to a rapid release of prostaglandins. However, as compared to gonads and myometrium, in-endometrium mechanisms of transmembrane signall...The functional significance of the endometrial hCG/ LH receptors has been related to a rapid release of prostaglandins. However, as compared to gonads and myometrium, in-endometrium mechanisms of transmembrane signalling of the hCG/LH receptors are probably not conventional and remain unclear. Here we investigated, in vivo, the potential of hCG to interact with, and stimulate the membrane effector enzyme, adenylyl cyclase (AC), in human endometrium. Hormonal and nonhormonal activation of AC was tested in membrane fractions prepared from endometrial biopsies obtained from patients undergoing evaluation cycles for hormone replacement therapy (HRT) and controlled ovarian hyperstimulation (COH). AC activity was determined by the direct conversion of the substrate ATP into cAMP under unstimulated conditions and in the presence of the non-hormonal activators guanyl nucleotide and forskolin. Also AC activity was tested in the presence of hCG under conditions allowing maximal enzyme stimulation. Isoproterenol and prostaglandin E2 (PGE2) were included for comparison. Immunoblot analyses demonstrated the presence of hCG/LH receptors and Gsα protein and other members of the G protein family in the membrane fractions. Endometrial membranes also exhibited high levels of AC activity compared to luteal membranes used as control. Stimulation by GMP-P(NH)P alone was 196 ± 63 (n = 8) (pmol/mg/ min ± SD). Neither hCG nor isoproterenol showed stimulation of endometrial AC (210 ± 65, and 197 ± 53, respectively;n = 66 assays). But PGE2 stimulated the enzyme system significantly (264 ± 63, p < 0.05;n = 66 assays). These data show that membrane fractions from human endometrium express all the AC system components, namely, hCG/LH receptors, Gsα protein and AC;however, hCG does not stimulate the endometrial AC system. Our data indicate that, in great contrast to gonadal receptors, endometrial hCG/ LH receptors are not coupled to the transmembrane AC effector. The well known release of eicosanoids in response to hCG suggests that these receptors are functional in human endometrium but throughout a signalling system different from AC. This enzyme is certainly coupled to and directly activated by eicosanoids and other embryonic signals.展开更多
Bone morphogenetic proteins（BMPs） play critical roles in follicle growth and development.BMPs initiate signaling by assembling BMP receptors and activating Smads,which in turn alter expression of target genes.The me...Bone morphogenetic proteins（BMPs） play critical roles in follicle growth and development.BMPs initiate signaling by assembling BMP receptors and activating Smads,which in turn alter expression of target genes.The mechanism underlying the regulation of the expression of BMP receptors and Smads during follicle development in pigs is still unknown.By quantitative real-time PCR,the mRNA expression of BMP receptors and Smads in granulosa cells（GC） was investigated.Cells were obtained from small porcine follicles（SF;3 mm diameter） and dominant follicles（DF;6 mm diameter）;ActR1A and BMPR2 mRNA levels in DF were significantly higher（P0.05） than that in SF,whereas BMPR1B,Smad4 and Smad7 expression tended to decrease（P0.05）.The levels of BMPR1A,ActR2,Smad1,Smad5,and Smad8 mRNA did not differ between DFs and SFs.To investigate the effect of LH on BMP receptors in GC,cells obtained from porcine DFs were cultured in medium supplemented with different doses of luteinizing hormone（LH）.High doses of LH（4 IU mL-1） significantly decreased the concentration of estradiol（E2） and progesterone（P4） in medium and the expression of Cyp19a1（P450 aromatase,P450arom） and Cyp11a1（cholesterol side-chain cleavage enzyme P450,P450scc）,while significantly increased viable cell numbers and up-regulated expression of cyclin dependent kinase-4（CDK4） and cyclin D2.However,LH had no effect on the expression of BMP receptor genes.Thus,the present study indicates that the expression of members of the BMP signaling pathway in porcine GC is regulated during follicle development and the expression of BMP receptors are not regulated by LH in porcine GCs.展开更多
In order to investigate the mechanism of progestin and antiprogestin in the regulation of ovarian steroidogenesis, a dual chamber culture system was prepared with the amnion membrane of human placenta. Isolated porci...In order to investigate the mechanism of progestin and antiprogestin in the regulation of ovarian steroidogenesis, a dual chamber culture system was prepared with the amnion membrane of human placenta. Isolated porcine granulosa and thecal cells from 4~6 mm diameter follicles were grown on both sides of the amnion, respectively, and co cultured with or without LNG and RU486. After 48 h incubation, the mRNAs of FSH receptor (FSH R) and LH receptor (LH R) of both cells were observed by in situ hybridization. The results showed that granulosa cells expressed both FSH R mRNA and LH R mRNA, while thecal cells expressed LH R mRNA only. Under the stimulation of FSH, both LNG and RU486 increased FSH R mRNA expression of granulosa cells. Under the stimulation of LH, LNG enhanced LH R mRNA expression of thecal cells; while RU486 decreased its expression. When granulosa and thecal cells were exposed to FSH and LH both, the actions of LNG and RU486 in thecal cells showed the same result as that stimulated by LH alone. In granulosa cells LNG decreased LH R mRNA expression, while RU486 increased its expression. These data suggest that: (1) granulosa cells expressed FSH R mRNA significantly; (2) both the progestin and antiprogestin directly acted on the mRNA expression of gonadotropin receptors of ovarian cells, but effects were different; (3) the response of granulosa or thecal cells to the action of LNG and RU486 was not the same. The mechanism needs to be further investigated.展开更多
文摘The functional significance of the endometrial hCG/ LH receptors has been related to a rapid release of prostaglandins. However, as compared to gonads and myometrium, in-endometrium mechanisms of transmembrane signalling of the hCG/LH receptors are probably not conventional and remain unclear. Here we investigated, in vivo, the potential of hCG to interact with, and stimulate the membrane effector enzyme, adenylyl cyclase (AC), in human endometrium. Hormonal and nonhormonal activation of AC was tested in membrane fractions prepared from endometrial biopsies obtained from patients undergoing evaluation cycles for hormone replacement therapy (HRT) and controlled ovarian hyperstimulation (COH). AC activity was determined by the direct conversion of the substrate ATP into cAMP under unstimulated conditions and in the presence of the non-hormonal activators guanyl nucleotide and forskolin. Also AC activity was tested in the presence of hCG under conditions allowing maximal enzyme stimulation. Isoproterenol and prostaglandin E2 (PGE2) were included for comparison. Immunoblot analyses demonstrated the presence of hCG/LH receptors and Gsα protein and other members of the G protein family in the membrane fractions. Endometrial membranes also exhibited high levels of AC activity compared to luteal membranes used as control. Stimulation by GMP-P(NH)P alone was 196 ± 63 (n = 8) (pmol/mg/ min ± SD). Neither hCG nor isoproterenol showed stimulation of endometrial AC (210 ± 65, and 197 ± 53, respectively;n = 66 assays). But PGE2 stimulated the enzyme system significantly (264 ± 63, p < 0.05;n = 66 assays). These data show that membrane fractions from human endometrium express all the AC system components, namely, hCG/LH receptors, Gsα protein and AC;however, hCG does not stimulate the endometrial AC system. Our data indicate that, in great contrast to gonadal receptors, endometrial hCG/ LH receptors are not coupled to the transmembrane AC effector. The well known release of eicosanoids in response to hCG suggests that these receptors are functional in human endometrium but throughout a signalling system different from AC. This enzyme is certainly coupled to and directly activated by eicosanoids and other embryonic signals.
基金supported by the National High Tech-nology Research & Development Program of China(2006AA10Z136)
文摘Bone morphogenetic proteins（BMPs） play critical roles in follicle growth and development.BMPs initiate signaling by assembling BMP receptors and activating Smads,which in turn alter expression of target genes.The mechanism underlying the regulation of the expression of BMP receptors and Smads during follicle development in pigs is still unknown.By quantitative real-time PCR,the mRNA expression of BMP receptors and Smads in granulosa cells（GC） was investigated.Cells were obtained from small porcine follicles（SF;3 mm diameter） and dominant follicles（DF;6 mm diameter）;ActR1A and BMPR2 mRNA levels in DF were significantly higher（P0.05） than that in SF,whereas BMPR1B,Smad4 and Smad7 expression tended to decrease（P0.05）.The levels of BMPR1A,ActR2,Smad1,Smad5,and Smad8 mRNA did not differ between DFs and SFs.To investigate the effect of LH on BMP receptors in GC,cells obtained from porcine DFs were cultured in medium supplemented with different doses of luteinizing hormone（LH）.High doses of LH（4 IU mL-1） significantly decreased the concentration of estradiol（E2） and progesterone（P4） in medium and the expression of Cyp19a1（P450 aromatase,P450arom） and Cyp11a1（cholesterol side-chain cleavage enzyme P450,P450scc）,while significantly increased viable cell numbers and up-regulated expression of cyclin dependent kinase-4（CDK4） and cyclin D2.However,LH had no effect on the expression of BMP receptor genes.Thus,the present study indicates that the expression of members of the BMP signaling pathway in porcine GC is regulated during follicle development and the expression of BMP receptors are not regulated by LH in porcine GCs.
文摘In order to investigate the mechanism of progestin and antiprogestin in the regulation of ovarian steroidogenesis, a dual chamber culture system was prepared with the amnion membrane of human placenta. Isolated porcine granulosa and thecal cells from 4~6 mm diameter follicles were grown on both sides of the amnion, respectively, and co cultured with or without LNG and RU486. After 48 h incubation, the mRNAs of FSH receptor (FSH R) and LH receptor (LH R) of both cells were observed by in situ hybridization. The results showed that granulosa cells expressed both FSH R mRNA and LH R mRNA, while thecal cells expressed LH R mRNA only. Under the stimulation of FSH, both LNG and RU486 increased FSH R mRNA expression of granulosa cells. Under the stimulation of LH, LNG enhanced LH R mRNA expression of thecal cells; while RU486 decreased its expression. When granulosa and thecal cells were exposed to FSH and LH both, the actions of LNG and RU486 in thecal cells showed the same result as that stimulated by LH alone. In granulosa cells LNG decreased LH R mRNA expression, while RU486 increased its expression. These data suggest that: (1) granulosa cells expressed FSH R mRNA significantly; (2) both the progestin and antiprogestin directly acted on the mRNA expression of gonadotropin receptors of ovarian cells, but effects were different; (3) the response of granulosa or thecal cells to the action of LNG and RU486 was not the same. The mechanism needs to be further investigated.
