The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Ilpo Huhtaniemi - One of the best experts on this subject based on the ideXlab platform.
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the Luteinizing Hormone Receptor knockout mouse as a tool to probe the in vivo actions of gonadotropic Hormones Receptors in females
Endocrinology, 2021Co-Authors: Ilpo Huhtaniemi, Kim Jonas, Adolfo Rivero Muller, Olayiwola Oduwole, Hellevi PeltoketoAbstract:Mouse models with altered gonadotropin functions have provided invaluable insight into the functions of these Hormones/Receptors. Here we describe the repurposing of the infertile and hypogonadal Luteinizing Hormone Receptor (LHR) knockout mouse model (LuRKO), to address outstanding questions in reproductive physiology. Using crossbreeding strategies and physiological and histological analyses, we first addressed the physiological relevance of forced LHR homomerization in female mice using BAC expression of 2 ligand-binding and signaling deficient mutant LHR, respectively, that have previously shown to undergo functional complementation and rescue the hypogonadal phenotype of male LuRKO mice. In female LuRKO mice, coexpression of signaling and binding deficient LHR mutants failed to rescue the hypogonadal and anovulatory phenotype. This was apparently due to the low-level expression of the 2 mutant LHR and potential lack of Luteinizing Hormone (LH)/LHR-dependent pleiotropic signaling that has previously been shown at high Receptor densities to be essential for ovulation. Next, we utilized a mouse model overexpressing human chorionic gonadotropin (hCG) with increased circulating "LH/hCG"-like bioactivity to ~40 fold higher than WT females, to determine if high circulating hCG in the LuRKO background could reveal putative LHR-independent actions. No effects were found, thus, suggesting that LH/hCG mediate their gonadal and non-gonadal effects solely via LHR. Finally, targeted expression of a constitutively active follicle stimulating Hormone Receptor (FSHR) progressed antral follicles to preovulatory follicles and displayed phenotypic markers of enhanced estrogenic activity but failed to induce ovulation in LuRKO mice. This study highlights the critical importance and precise control of functional LHR and FSHR for mediating ovarian functions and of the potential repurposing of existing genetically modified mouse models in answering outstanding questions in reproductive physiology.
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the Luteinizing Hormone Receptor knock out mouse as a tool to probe the in vivo actions of gonadotropic Hormones Receptors in females
Endocrinology, 2021Co-Authors: Ilpo Huhtaniemi, Kim Jonas, Adolfo Rivero Muller, Olayiwola Oduwole, Hellevi PeltoketoAbstract:Mouse models with altered gonadotropin functions have provided invaluable insight into the functions of these Hormones/Receptors. Here we describe the repurposing of the infertile and hypogonadal Luteinizing Hormone Receptor (LHR) knockout mouse model (LuRKO), to address outstanding questions in reproductive physiology. Using crossbreeding strategies and physiological and histological analyses, we first addressed the physiological relevance of forced LHR homomerization in female mice using BAC expression of 2 ligand-binding and signaling deficient mutant LHR, respectively, that have previously shown to undergo functional complementation and rescue the hypogonadal phenotype of male LuRKO mice. In female LuRKO mice, coexpression of signaling and binding deficient LHR mutants failed to rescue the hypogonadal and anovulatory phenotype. This was apparently due to the low-level expression of the 2 mutant LHR and potential lack of Luteinizing Hormone (LH)/LHR-dependent pleiotropic signaling that has previously been shown at high Receptor densities to be essential for ovulation. Next, we utilized a mouse model overexpressing human chorionic gonadotropin (hCG) with increased circulating "LH/hCG"-like bioactivity to ~40 fold higher than WT females, to determine if high circulating hCG in the LuRKO background could reveal putative LHR-independent actions. No effects were found, thus, suggesting that LH/hCG mediate their gonadal and non-gonadal effects solely via LHR. Finally, targeted expression of a constitutively active follicle stimulating Hormone Receptor (FSHR) progressed antral follicles to preovulatory follicles and displayed phenotypic markers of enhanced estrogenic activity but failed to induce ovulation in LuRKO mice. This study highlights the critical importance and precise control of functional LHR and FSHR for mediating ovarian functions and of the potential repurposing of existing genetically modified mouse models in answering outstanding questions in reproductive physiology.
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compound heterozygous mutations in the Luteinizing Hormone Receptor signal peptide causing 46 xy disorder of sex development
European Journal of Endocrinology, 2019Co-Authors: Iulia Potorac, Ilpo Huhtaniemi, Ashutosh Trehan, Kamila Szymanska, Julie Fudvoye, Albert Thiry, Adrian Daly, Albert BeckersAbstract:Testosterone production by the fetal testis depends on a functional relationship between hCG and the LH/chorionic gonadotropin Receptor (LHCGR). Failure of the Receptor to correctly respond to its ligand leads to impaired sexual differentiation in males. A phenotypically female patient with pubertal delay had a 46,XY karyotype and was diagnosed with 46,XY disorder of sex development (DSD). Novel compound heterozygous LHCGR mutations were found in the signal peptide: a duplication p.L10_Q17dup of maternal origin, and a deletion (p.K12_L15del) and a p.L16Q missense mutation of paternal origin. cAMP production was very low for both the deletion and duplication mutations and was halved for the missense mutant. The duplication and missense mutations were both expressed intracellularly, but at very low levels at the cell membrane; they were most likely retained in the endoplasmic reticulum. The deletion mutant had a very limited intracellular expression, indicating impaired biosynthesis. There was reduced expression of all three mutants, which was most marked for the deletion mutation. There was also decreased protein expression of all three mutant Receptors. In the deletion mutation, the presence of a lower-molecular-weight band corresponding to LHCGR monomer, probably due to lack of glycosylation, and a lack of bands corresponding to dimers/oligomers suggests absent ER entry. This novel case of 46,XY DSD illustrates how different LHCGR signal peptide mutations led to complete Receptor inactivation by separate mechanisms. The study underlines the importance of specific regions of signal peptides and expands the spectrum of LHCGR mutations.
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adrenocortical tumorigenesis Luteinizing Hormone Receptor and transcription factors gata 4 and gata 6
Molecular and Cellular Endocrinology, 2007Co-Authors: Susanna Vuorenoja, Markku Heikinheimo, David B. Wilson, Malgorzata Bielinska, Sanne Kiiveri, Adolfo Riveromuller, Ilpo Huhtaniemi, Nafis A RahmanAbstract:Abstract Luteinizing Hormone (LH/hCG) responsiveness of normal and pathological human adrenal glands as well as the possibility of constitutive expressions of Luteinizing Hormone Receptor (LHR) in adrenal cortex has been reported. Some recent studies showed a correlation between the LHR and abundant GATA-4 expression in both metastasizing and non-metastasizing human adrenocortical tumors, but not in normal adrenals, implicating the putative relevance of LHR and GATA-4 for adrenocortical pathophysiology. However, the physio- and pathophysiological significance of LHR and GATA-4 in the mechanism of adrenocortical tumorigenesis remains unclear. The paucity of suitable models for adrenal tumorigenesis makes the establishment of proper animal models highly important. LHR expression in the murine adrenal gland is an exception and not found in wild-type (WT) animal. We have previously shown that ectopic LHR expression in the murine adrenal gland can be induced by chronically elevated LH levels. We have generated a gonadotropin-responsive adrenal tumor model in gonadectomized transgenic (TG) mice expressing the inhibin α promoter/Simian Virus 40 T antigen transgene (inhα/Tag). Given the induction of expression and regulation of GATA-4 and GATA-6 zinc finger transcription factors in the gonads by gonadotropins, this review will explore their relationship to LHR expression and their role in adrenocortical tumorigenesis. A functional link between LHR and GATA-4 actions in the adrenal pathophysiology is proposed.
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testosterone replacement therapy induces spermatogenesis and partially restores fertility in Luteinizing Hormone Receptor knockout mice
Endocrinology, 2005Co-Authors: Tomi Pakarainen, Ilpo Huhtaniemi, Fuping Zhang, Matti Poutanen, Sari MakelaAbstract:Testosterone (T) is essential for spermatogenesis, fertility, and maintenance of the male phenotype. We analyzed in hypogonadal LH Receptor knockout (LuRKO) male mice whether T treatment can restore their phenotype, spermatogenesis, and fertility. In LuRKO mice, spermatogenesis is arrested at round spermatids, adult-type Leydig cells are absent, T production is dramatically decreased, the animals are cryptorchid, and their accessory sex organs are atrophic. T replacement therapy from 21 d of life for 60 or 120 d in LuRKO mice induced a male phenotype macroscopically indistinguishable from that of wild-type littermates as well as full spermatogenesis and testicular descent. Thus, the absence of LH-dependent prepubertal androgen priming is not necessary for subsequent maturation of the male phenotype. Conspicuously, some abnormalities remained in epididymal histology after T treatment despite normal expression of several epididymis-specific genes in caput epididymis. The mice displayed normal mating behavior, although at lower frequency than wild-type controls. The spermatozoa were able to fertilize oocytes, but their impaired passage from epididymis to uterus was apparent. The mice remained subfertile, because only 9% of all breedings resulted in pregnancy, and only two of 13 mice (15%) were fertile. Moreover, inflammation in epididymides and prostate was found in many T-treated LuRKO mice, which probably impaired sperm transport and contributed to their high rate of subfertility. In conclusion, T replacement initiated prepubertally only partially restores the fertility of LuRKO mice, even though most features of the male phenotype recover. Full fertility may require higher and/or earlier postnatal T exposure or production of other Leydig cell factors lacking in this model.
K. M. J. Menon - One of the best experts on this subject based on the ideXlab platform.
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association between lh Receptor regulation and ovarian hyperstimulation syndrome in a rodent model
Reproduction, 2020Co-Authors: Cuihong Zheng, Bindu Menon, Thippeswamy Gulappa, K. M. J. MenonAbstract:Ovarian hyperstimulation syndrome (OHSS) is a common complication of ovarian stimulation associated with the administration of human chorionic gonadotropin (hCG) during assisted reproduction. We have determined the expression of Luteinizing Hormone Receptor (Lhcgr) mRNA, vascular endothelial growth factor (VEGF), and its transcription factor, HIF1α, during the periovulatory period in a rodent model of OHSS and compared these results with normal ovulatory periods. These results showed that the downregulation of Lhcgr mRNA in response to conditions that mimic preovulatory LH surge was significantly impaired in the OHSS group compared to the complete downregulation seen in the control group. Most importantly, the downregulation of Luteinizing Hormone Receptor mRNA expression following hCG administration was sustained in the control group up to 48 h, whereas it remained at significantly higher levels in the OHSS group. This impairment of hCG-induced Lhcgr downregulation in the OHSS group was accompanied by significantly elevated levels of VEGF and its transcription factor, HIF1α. Furthermore, the downregulation of Lhcgr that occurs in response to a preovulatory LH surge in normal cycles was accompanied by low levels of VEGF. This study shows that, while downregulation of Lhcgr as well as low VEGF levels are seen in response to a preovulatory LH surge in normal ovarian cycle, impaired Lhcgr downregulation and elevated VEGF levels were found in the OHSS group.
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Regulation of Luteinizing Hormone Receptor mRNA Expression in the Ovary: The Role of miR-122
Vitamins and Hormones, 2018Co-Authors: K. M. J. Menon, Bindu Menon, Thippeswamy GulappaAbstract:The expression of Luteinizing Hormone Receptor (LHR) in the mammalian ovary is regulated in response to changes in the secretion of follicle-stimulating Hormone and Luteinizing Hormone by the anterior pituitary, at least in part, through posttranscriptional mechanisms. The steady-state levels of LHR mRNA are maintained by controlling its rate of degradation by an RNA-binding protein designated as LHR mRNA-binding protein (LRBP). LRBP forms a complex with LHR mRNA and targets it for degradation in the p bodies. miR-122, an 18 nucleotide noncoding RNA, regulates the expression of LRBP. Thus, the levels of miR-122 determine the cellular levels of LHR mRNA expression. This phenomenon has been examined during the induction of LHR mRNA expression that occurs during follicle maturation in response to rising levels of FSH. In this situation, miR-122 and LRBP levels decrease as LHR mRNA expression undergoes downregulation in response to preovulatory LH surge. miR-122 expression as well as LRBP levels show robust increases. The mechanism of induction of LRBP by miR-122 has also been discussed.
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Post-transcriptional Regulation of Luteinizing Hormone Receptor mRNA Expression in the Ovary
Post-transcriptional Mechanisms in Endocrine Regulation, 2015Co-Authors: K. M. J. Menon, Bindu Menon, Thippeswamy GulappaAbstract:Regulated degradation of Luteinizing Hormone Receptor (LHR) mRNA through post-transcriptional mechanisms plays an important role in regulating LH Receptor expression in response to changes in the secretion of LH from the pituitary gland. A specific LHR mRNA binding protein (LRBP), identified as mevalonate kinase, binds to nucleotides 203–220 in the coding region of LHR mRNA and exhibits specificity for this region. The LHR mRNA binding protein caused accelerated LHR mRNA decay through translational suppression of LHR mRNA. Furthermore, LRBP interacts with other proteins identified by yeast two hybrid screens. Among these, eukaryotic initiation factor 5A (eIF5A) undergoes hypusination and plays a regulatory role by interacting with LHR mRNA-LRBP complex. Inhibition of hypusination of eIF5A reduces the ability of LHR mRNA to undergo ligand-induced downregulation. We have identified a small non-coding RNA, miR-122 that plays a role in LHR mRNA expression by regulating LRBP via sterol regulatory element binding protein (SREBP). The post-transcriptional mechanism described here provides a novel means to regulate the steady state levels of LHR, a molecule that plays a central role in mammalian reproduction, by controlling the degradation of its mRNA during ovarian cycle.
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hypusination of eukaryotic initiation factor 5a via camp pka erk1 2 pathway is required for ligand induced downregulation of lh Receptor mrna expression in the ovary
Molecular and Cellular Endocrinology, 2015Co-Authors: Thippeswamy Gulappa, Bindu Menon, K. M. J. MenonAbstract:Luteinizing Hormone Receptor (LHR) mRNA expression in the ovary is regulated post-transcriptionally by an LH Receptor mRNA binding protein (LRBP). Eukaryotic initiation factor 5A (EIF5A), identified as an LRBP-interacting protein plays a crucial role in LHR mRNA expression. In this study, we have demonstrated that during hCG-induced LHR downregulation, a significant upregulation of eIF5A mRNA expression and hypusination of eIF5A protein occurs in a time dependent manner. Pretreatment with H89, a specific inhibitor of PKA, and U0126, a specific inhibitor of ERK1/2 significantly inhibited both hCG-induced eIF5A mRNA expression and hypusination of eIF5A protein. Pretreatment with GC7, a specific inhibitor of eIF5A hypusination significantly abolished hCG-induced LRBP mRNA and protein expression. Furthermore, GC7 pretreatment significantly inhibited hCG-induced interaction of LRBP with LHR mRNA as assessed by RNA electrophoretic mobility gel shift assay (REMSA). GC7 treatment also reversed LHR mRNA downregulation. Taken together, these results suggest that hCG-induced LHR mRNA downregulation is mediated by cAMP-PKA-ERK1/2 signaling leading to activation of eIF5A hypusination.
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eukaryotic initiation factor 5a plays an essential role in Luteinizing Hormone Receptor regulation
Molecular Endocrinology, 2014Co-Authors: Bindu Menon, Thippeswamy Gulappa, K. M. J. MenonAbstract:Down-regulation of LH Receptor (LHR) in the ovary by its ligand is mediated by a specific RNA-binding protein, designated LH Receptor mRNA–binding protein (LRBP), through translational suppression and mRNA degradation. Using yeast 2-hybrid screens, we previously identified eukaryotic initiation factor 5A (eIF5A) as one of the proteins that interacts with LRBP during LHR mRNA down-regulation. The present study examined the role of eIF5A and its hypusination in the context of LHR mRNA down-regulation. The association of eIF5A with LRBP or LHR mRNA was determined using immunoprecipitation and RNA immunoprecipitation assays. The results showed that the association of eIF5A with the LHR mRNA-LRBP complex increased significantly during down-regulation. Furthermore, gel fractionation and the hypusination activity assay both showed increased hypusination of eIF5A during LHR mRNA down-regulation. Abolishment of hypusination by pretreatment with the chemical inhibitor GC7 prevented the association of eIF5A with LHR mRNA and LRBP. Inhibition of hypusination also reduced the extent of ligand-induced down-regulation of LHR mRNA as well as the expression of functional LHRs assessed by real-time PCR and 125I-human chorionic gonadotropin (hCG) binding assays, respectively. The loss of human chorionic gonadotropin–mediated downstream signaling during LHR down-regulation was also restored by inhibition of hypusination of eIF5A. Thus, the present study, for the first time, reveals the crucial role of eIF5A and its hypusination in the regulation of LHR expression in the ovary.
Bindu Menon - One of the best experts on this subject based on the ideXlab platform.
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association between lh Receptor regulation and ovarian hyperstimulation syndrome in a rodent model
Reproduction, 2020Co-Authors: Cuihong Zheng, Bindu Menon, Thippeswamy Gulappa, K. M. J. MenonAbstract:Ovarian hyperstimulation syndrome (OHSS) is a common complication of ovarian stimulation associated with the administration of human chorionic gonadotropin (hCG) during assisted reproduction. We have determined the expression of Luteinizing Hormone Receptor (Lhcgr) mRNA, vascular endothelial growth factor (VEGF), and its transcription factor, HIF1α, during the periovulatory period in a rodent model of OHSS and compared these results with normal ovulatory periods. These results showed that the downregulation of Lhcgr mRNA in response to conditions that mimic preovulatory LH surge was significantly impaired in the OHSS group compared to the complete downregulation seen in the control group. Most importantly, the downregulation of Luteinizing Hormone Receptor mRNA expression following hCG administration was sustained in the control group up to 48 h, whereas it remained at significantly higher levels in the OHSS group. This impairment of hCG-induced Lhcgr downregulation in the OHSS group was accompanied by significantly elevated levels of VEGF and its transcription factor, HIF1α. Furthermore, the downregulation of Lhcgr that occurs in response to a preovulatory LH surge in normal cycles was accompanied by low levels of VEGF. This study shows that, while downregulation of Lhcgr as well as low VEGF levels are seen in response to a preovulatory LH surge in normal ovarian cycle, impaired Lhcgr downregulation and elevated VEGF levels were found in the OHSS group.
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Regulation of Luteinizing Hormone Receptor mRNA Expression in the Ovary: The Role of miR-122
Vitamins and Hormones, 2018Co-Authors: K. M. J. Menon, Bindu Menon, Thippeswamy GulappaAbstract:The expression of Luteinizing Hormone Receptor (LHR) in the mammalian ovary is regulated in response to changes in the secretion of follicle-stimulating Hormone and Luteinizing Hormone by the anterior pituitary, at least in part, through posttranscriptional mechanisms. The steady-state levels of LHR mRNA are maintained by controlling its rate of degradation by an RNA-binding protein designated as LHR mRNA-binding protein (LRBP). LRBP forms a complex with LHR mRNA and targets it for degradation in the p bodies. miR-122, an 18 nucleotide noncoding RNA, regulates the expression of LRBP. Thus, the levels of miR-122 determine the cellular levels of LHR mRNA expression. This phenomenon has been examined during the induction of LHR mRNA expression that occurs during follicle maturation in response to rising levels of FSH. In this situation, miR-122 and LRBP levels decrease as LHR mRNA expression undergoes downregulation in response to preovulatory LH surge. miR-122 expression as well as LRBP levels show robust increases. The mechanism of induction of LRBP by miR-122 has also been discussed.
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Post-transcriptional Regulation of Luteinizing Hormone Receptor mRNA Expression in the Ovary
Post-transcriptional Mechanisms in Endocrine Regulation, 2015Co-Authors: K. M. J. Menon, Bindu Menon, Thippeswamy GulappaAbstract:Regulated degradation of Luteinizing Hormone Receptor (LHR) mRNA through post-transcriptional mechanisms plays an important role in regulating LH Receptor expression in response to changes in the secretion of LH from the pituitary gland. A specific LHR mRNA binding protein (LRBP), identified as mevalonate kinase, binds to nucleotides 203–220 in the coding region of LHR mRNA and exhibits specificity for this region. The LHR mRNA binding protein caused accelerated LHR mRNA decay through translational suppression of LHR mRNA. Furthermore, LRBP interacts with other proteins identified by yeast two hybrid screens. Among these, eukaryotic initiation factor 5A (eIF5A) undergoes hypusination and plays a regulatory role by interacting with LHR mRNA-LRBP complex. Inhibition of hypusination of eIF5A reduces the ability of LHR mRNA to undergo ligand-induced downregulation. We have identified a small non-coding RNA, miR-122 that plays a role in LHR mRNA expression by regulating LRBP via sterol regulatory element binding protein (SREBP). The post-transcriptional mechanism described here provides a novel means to regulate the steady state levels of LHR, a molecule that plays a central role in mammalian reproduction, by controlling the degradation of its mRNA during ovarian cycle.
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hypusination of eukaryotic initiation factor 5a via camp pka erk1 2 pathway is required for ligand induced downregulation of lh Receptor mrna expression in the ovary
Molecular and Cellular Endocrinology, 2015Co-Authors: Thippeswamy Gulappa, Bindu Menon, K. M. J. MenonAbstract:Luteinizing Hormone Receptor (LHR) mRNA expression in the ovary is regulated post-transcriptionally by an LH Receptor mRNA binding protein (LRBP). Eukaryotic initiation factor 5A (EIF5A), identified as an LRBP-interacting protein plays a crucial role in LHR mRNA expression. In this study, we have demonstrated that during hCG-induced LHR downregulation, a significant upregulation of eIF5A mRNA expression and hypusination of eIF5A protein occurs in a time dependent manner. Pretreatment with H89, a specific inhibitor of PKA, and U0126, a specific inhibitor of ERK1/2 significantly inhibited both hCG-induced eIF5A mRNA expression and hypusination of eIF5A protein. Pretreatment with GC7, a specific inhibitor of eIF5A hypusination significantly abolished hCG-induced LRBP mRNA and protein expression. Furthermore, GC7 pretreatment significantly inhibited hCG-induced interaction of LRBP with LHR mRNA as assessed by RNA electrophoretic mobility gel shift assay (REMSA). GC7 treatment also reversed LHR mRNA downregulation. Taken together, these results suggest that hCG-induced LHR mRNA downregulation is mediated by cAMP-PKA-ERK1/2 signaling leading to activation of eIF5A hypusination.
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eukaryotic initiation factor 5a plays an essential role in Luteinizing Hormone Receptor regulation
Molecular Endocrinology, 2014Co-Authors: Bindu Menon, Thippeswamy Gulappa, K. M. J. MenonAbstract:Down-regulation of LH Receptor (LHR) in the ovary by its ligand is mediated by a specific RNA-binding protein, designated LH Receptor mRNA–binding protein (LRBP), through translational suppression and mRNA degradation. Using yeast 2-hybrid screens, we previously identified eukaryotic initiation factor 5A (eIF5A) as one of the proteins that interacts with LRBP during LHR mRNA down-regulation. The present study examined the role of eIF5A and its hypusination in the context of LHR mRNA down-regulation. The association of eIF5A with LRBP or LHR mRNA was determined using immunoprecipitation and RNA immunoprecipitation assays. The results showed that the association of eIF5A with the LHR mRNA-LRBP complex increased significantly during down-regulation. Furthermore, gel fractionation and the hypusination activity assay both showed increased hypusination of eIF5A during LHR mRNA down-regulation. Abolishment of hypusination by pretreatment with the chemical inhibitor GC7 prevented the association of eIF5A with LHR mRNA and LRBP. Inhibition of hypusination also reduced the extent of ligand-induced down-regulation of LHR mRNA as well as the expression of functional LHRs assessed by real-time PCR and 125I-human chorionic gonadotropin (hCG) binding assays, respectively. The loss of human chorionic gonadotropin–mediated downstream signaling during LHR down-regulation was also restored by inhibition of hypusination of eIF5A. Thus, the present study, for the first time, reveals the crucial role of eIF5A and its hypusination in the regulation of LHR expression in the ovary.
Maria L. Dufau - One of the best experts on this subject based on the ideXlab platform.
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interaction of positive coactivator 4 with histone 3 3 protein is essential for transcriptional activation of the Luteinizing Hormone Receptor gene
Biochimica et Biophysica Acta, 2018Co-Authors: Peng Zhao, Mingjuan Liao, Raghuveer Kavarthapu, Rajakumar Anbazhagan, Maria L. DufauAbstract:The Luteinizing Hormone Receptor (LHR) is essential for sexual development and reproduction in mammals. We have established that Sp1 has a central role in derepression of LHR gene transcription induced by Trichostatin A (TSA) in MCF7 cells. Moreover, the co-activator PC4 which associates directly with Sp1 at the LHR promoter is essential for TSA-mediated LHR transcription. This study explores interactions of PC4 with histone proteins, which presumably triggers chromatin modifications during LHR transcriptional activation. TSA treatment of MCF7 cells expressing PC4-Flag protein induces acetylation of histone 3 (H3) and immunoprecipitation (IP) studies revealed its interaction with PC4-Flag protein. MS/MS analysis of the protein complex obtained after IP from TSA treated samples detected H3.3 acetylated at K9, K14, K18, K23 and K27 as a PC4 interacting protein. The association of PC4 with H3.3 was corroborated by IP and re-ChIP using H3.3 antibody. Similarly, IP and re-ChIP showed association of PC4 with H3 acetylated protein. Knockdown of PC4 in MCF7 cells reduced H3.3 enrichment, H3 acetylation at the Lys sites and LHR promoter activity in TSA treated cells despite an increase in H3 and H3.3 protein induced by TSA, linking PC4 to H3 acetylation and LHR transcription. Depletion of H3.3 A/B in MCF7 cells impair chromatin accessibility and enrichment of Pol II and TFIIB at the LHR promoter and its activation, resulting in marked reduction of LHR gene expression. Together, these findings point to the critical role of PC4 and its association with acetylated H3.3 in TSA-induced LHR gene transcription.
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coactivator function of positive cofactor 4 pc4 in sp1 directed Luteinizing Hormone Receptor lhr gene transcription
Journal of Biological Chemistry, 2011Co-Authors: Mingjuan Liao, Ying Zhang, Junghoon Kang, Maria L. DufauAbstract:The LHR has an essential role in sexual development and reproductive function, and its transcription is subjected to several modes of regulation. In this study, we investigated PC4 coactivator function in the control of LHR transcription. Knockdown of PC4 by siRNA inhibited the LHR basal promoter activity and trichostatin A (TSA)-induced gene transcriptional activation and expression in MCF-7 cells. While overexpression of PC4 alone had no effect on the LHR gene, it significantly enhanced Sp1- but not Sp3-mediated LHR transcriptional activity. PC4 directly interacts with Sp1 at the LHR promoter, and this interaction is negatively regulated by PC4 phosphorylation. The coactivator domain (22–91 aa) of PC4 and DNA binding domain of Sp1 are essential for PC4/Sp1 interaction. ChIP assay revealed significant occupancy of PC4 at the LHR promoter that increased upon TSA treatment. Disruption of PC4 expression significantly reduced TSA-induced recruitment of TFIIB and RNAP II, at the promoter. PC4 functions are beyond TSA-induced phosphatase release, PI3K-mediated Sp1 phosphorylation, and HDAC1/2/mSin3A co-repressor release indicating its role as linker coactivator of Sp1 and the transcriptional machinery. These findings demonstrated a critical aspect of LHR modulation whereby PC4 acts as a coactivator of Sp1 to contribute to the human of LHR transcription.
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participation of signaling pathways in the derepression of Luteinizing Hormone Receptor transcription
Molecular and Cellular Endocrinology, 2010Co-Authors: Maria L. Dufau, Mingjuan Liao, Ying ZhangAbstract:The Luteinizing Hormone Receptor (LHR) transcription is subject to an epigenetic regulatory mode whereby the proximal Sp1 site acts as an anchor to recruit histone deacetylases (HDAC)1/2 and the Sin3A co-repressor complex. This results in promoter-localized histone hypo-acetylation that contributes to the silencing of LHR transcriptional expression. Chromatin changes resulting from site-specific acetylation and methylation of histones regulate LHR gene expression. The HDAC inhibitor TSA-induced cell-specific phosphatase release from the promoter, which serves as an 'on' mechanism for Sp1 phosphorylation by phosphatidylinositol 3-kinase/protein kinase Czeta (PI3K/PKCzeta) at Ser641, leading to p107 repressor derecruitment and LHR transcriptional activation. The methylation status of the promoter provides another layer of modulation in a cell-specific manner. Maximal derepression of the LHR gene is dependent on complete DNA demethylation of the promoter in conjunction with histone hyperacetylation and release of repressors (p107 and HDAC/Sin3A). Independently, the PKC-alpha/Erk pathway, participates in LHR gene expression through induction of Sp1 phosphorylation at Ser site(s) other than Ser641. This causes dissociation of the HDAC1/mSin3A from the promoter, recruitment of TFIIB and Pol II, and transcriptional activation. Collectively, these findings demonstrate that LHR gene expression at the transcriptional level is regulated by complex and diverse networks, in which coordination and interactions between these regulatory effectors are crucial for silencing/activation of LHR expression.
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Unlocking repression of the human Luteinizing Hormone Receptor gene by trichostatin A-induced cell-specific phosphatase release.
Journal of Biological Chemistry, 2008Co-Authors: Ying Zhang, Mingjuan Liao, Maria L. DufauAbstract:Our previous studies demonstrated that the histone deacetylase inhibitor, trichostatin A (TSA), induces derepression of the human Luteinizing Hormone Receptor (LHR) gene by de-recruitment of the pRB homologue p107 repressor from the promoter in JAR and MCF-7 cancer cells. TSA initiates a mechanism whereby the phosphatidylinositol 3-kinase/protein kinase zeta (PKCzeta) cascade phosphorylates Sp1 at Ser-641, which is essential for the release of the repression of LHR transcription. The present studies have revealed that dissociation of serine/threonine protein phosphatases PP2A and PP1 from the LHR promoter mediates TSA-induced activation of LHR gene transcription in a cell-specific manner. Changes in chromatin structure induced by TSA cause the release of PP2A in JAR cells or of PP1 in MCF-7 cells, which is associated with Sp1 directly or through histone deacetylase 1/2, respectively, at the promoter. This favors the phosphorylation of Sp1 mediated by the phosphatidylinositol 3-kinase/PKCzeta pathway, which in turn causes the release of the p107 inhibitor from Sp1 and marked transcriptional activation of the LHR. These findings reveal the importance of phosphatases in the control of LHR transcription, where the balance between phosphatidylinositol 3-kinase/PKCzeta and phosphatases could be critical for up- and down-regulation of LHR gene expression in physiological and pathological settings.
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phosphatidylinositol 3 kinase protein kinase cζ induced phosphorylation of sp1 and p107 repressor release have a critical role in histone deacetylase inhibitor mediated derepression of transcription of the Luteinizing Hormone Receptor gene
Molecular and Cellular Biology, 2006Co-Authors: Ying Zhang, Mingjuan Liao, Maria L. DufauAbstract:We have demonstrated that silencing of Luteinizing Hormone Receptor (LHR) gene transcription is mediated via a proximal Sp1 site at its promoter. Trichostatin A (TSA) induced histone acetylation and gene activation in JAR cells that prevailed in the absence of changes in Sp1/Sp3 expression, their binding activity, disassociation of the histone deacetylase/mSin3A complex from the Sp1 site, or demethylation of the promoter. This indicated a different mechanism involved in TSA-induced derepression. The present studies have revealed that phosphatidylinositol 3-kinase/protein kinase Czeta (PI3K/PKCzeta)-mediated Sp1 phosphorylation accounts for Sp1 site-dependent LHR gene activation. TSA caused marked phosphorylation of Sp1 at serine 641 in JAR and MCF-7 cells. Blockade of PI3K or PKCzeta activity by specific inhibitors, kinase-deficient mutants, or small interfering RNA abolished the effect of TSA on the LHR gene and Sp1 phosphorylation. PKCzeta was shown to associate with Sp1, and this association was enhanced by TSA. Sp1 phosphorylation at serine 641 was required for the release of the pRb homologue p107 from the LHR gene promoter, while p107 acted as a repressor of the LHR gene. Inhibition of PKCzeta activity blocked the dissociation of p107 from the LHR gene promoter and markedly reduced Sp1 phosphorylation and transcription. These results have demonstrated that phosphorylation of Sp1 by PI3K/PKCzeta is critical for TSA-activated LHR gene expression. These studies have revealed a novel mechanism of TSA action through derecruitment of a repressor from the LHR gene promoter in a PI3K/PKCzeta-induced Sp1 phosphorylation-dependent manner.
Kelly E Mayo - One of the best experts on this subject based on the ideXlab platform.
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cellular localization and hormonal regulation of follicle stimulating Hormone and Luteinizing Hormone Receptor messenger rnas in the rat ovary
Molecular Endocrinology, 1991Co-Authors: Tamara A Camp, Jason O Rahal, Kelly E MayoAbstract:The pituitary gonadotropins FSH and LH are key Hormones for regulating gametogenesis and steroidogenesis in the ovary and testis. The cell surface Receptors that mediate the biological activities of these Hormones are thought to be expressed in a cell-specific fashion in the ovary and are regulated as animals progress through the reproductive cycle. Using cloned Receptor cDNAs, we have examined the expression and hormonal regulation of the ovarian FSH and LH Receptor mRNAs in the rat. A quantitative reverse transcription-polymerase chain reaction amplification scheme was used to measure relative levels of the FSH and LH Receptor mRNAs, while in situ hybridization was used to localize FSH and LH Receptor transcripts. In immature animals, low levels of FSH Receptor mRNA are observed in the granulosa cells of small follicles, while low levels of LH Receptor mRNA are found in the thecal cells of these same follicles. After stimulation with PMSG, levels of both mRNAs increase, and the LH Receptor mRNA is local...
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cellular localization and hormonal regulation of follicle stimulating Hormone and Luteinizing Hormone Receptor messenger rnas in the rat ovary
Molecular Endocrinology, 1991Co-Authors: Tamara A Camp, Jason O Rahal, Kelly E MayoAbstract:The pituitary gonadotropins FSH and LH are key Hormones for regulating gametogenesis and steroidogenesis in the ovary and testis. The cell surface Receptors that mediate the biological activities of these Hormones are thought to be expressed in a cell-specific fashion in the ovary and are regulated as animals progress through the reproductive cycle. Using cloned Receptor cDNAs, we have examined the expression and hormonal regulation of the ovarian FSH and LH Receptor mRNAs in the rat. A quantitative reverse transcription-polymerase chain reaction amplification scheme was used to measure relative levels of the FSH and LH Receptor mRNAs, while in situ hybridization was used to localize FSH and LH Receptor transcripts. In immature animals, low levels of FSH Receptor mRNA are observed in the granulosa cells of small follicles, while low levels of LH Receptor mRNA are found in the thecal cells of these same follicles. After stimulation with PMSG, levels of both mRNAs increase, and the LH Receptor mRNA is localized in both the granulosa and thecal cells of large follicles. Further treatment of PMSG-primed animals with hCG results in down-regulation, particularly of the LH Receptor mRNA in granulosa cells. In adult animals, LH Receptor mRNA levels change dramatically during the estrous cycle, particularly after the preovulatory LH surge. FSH Receptor mRNA levels show a similar pattern of change, but the FSH Receptor mRNA is of lower abundance and is not as highly regulated as the LH Receptor mRNA. FSH Receptor mRNA is confined to the granulosa cells of healthy developing follicles, whereas LH Receptor mRNA is localized predominantly to thecal cells of small follicles on estrous morning, then appears in the granulosa cells of growing follicles by diestrous morning. LH Receptor mRNA is also found in interstitial tissues and corpora lutea throughout much of the estrous cycle. Our results indicate that the gonadotropin Receptor genes are regulated in a complex fashion during the recruitment, maturation, and ovulation of the ovarian follicle.
