Hajime Oishi

Nuclear Receptor Function Requires a TFTC-Type Histone Acetyl Transferase Complex.

Nuclear receptors (NRs) regulate transcription in a ligand-dependent way through two types of coactivator complexes: the p160/CBP histone acetyl transferase (HAT) complex and the DRIP/TRAP/SMCC complex without HAT activity. Here we identified a large human (h) coactivator complex necessary for the estrogen receptor alpha (ERalpha) transactivation. This complex contains the GCN5 HAT, the c-Myc interacting protein TRRAP/PAF400, TAF(II)30, and other subunits. Similarly to known TFTC (TBP-free TAF(II)-containing)-type HAT complexes (hTFTC, hPCAF, and hSTAGA), TRRP directly interacted with liganded ER alpha, or other NRs. ER alpha transactivation was enhanced by the purified complex in vitro. Antisense TRRAP RNA inhibited estrogen-dependent cell growth of breast cancer cells. Thus, the isolated TFTC-type HAT complex acts as a third class of coactivator complex for NR function.

Resveratrol promotes expression of SIRT1 and StAR in rat ovarian granulosa cells: An implicative role of SIRT1 in the ovary

BackgroundResveratrol is a natural polyphenolic compound known for its beneficial effects on energy homeostasis, and it also has multiple properties, including anti-oxidant, anti-inflammatory, and anti-tumor activities. Recently, silent information regulator genes (Sirtuins) have been identified as targets of resveratrol. Sirtuin 1 (SIRT1), originally found as an NAD+-dependent histone deacetylase, is a principal modulator of pathways downstream of calorie restriction, and the activation of SIRT1 ameliorates glucose homeostasis and insulin sensitivity. To date, the presence and physiological role of SIRT1 in the ovary are not known. Here we found that SIRT1 was localized in granulosa cells of the human ovary.MethodsThe physiological roles of resveratrol and SIRT1 in the ovary were analyzed. Immunohistochemistry was performed to localize the SIRT1 expression. SIRT1 protein expression of cultured cells and luteinized human granulosa cells was investigated by Western blot. Rat granulosa cells were obtained from diethylstilbestrol treated rats. The cells were treated with increasing doses of resveratrol, and subsequently harvested to determine mRNA levels and protein levels. Cell viability was tested by MTS assay. Cellular apoptosis was analyzed by caspase 3/7 activity test and Hoechst 33342 staining.ResultsSIRT1 protein was expressed in the human ovarian tissues and human luteinized granulosa cells. We demonstrated that resveratrol exhibited a potent concentration-dependent inhibition of rat granulosa cells viability. However, resveratrol-induced inhibition of rat granulosa cells viability is independent of apoptosis signal. Resveratrol increased mRNA levels of SIRT1, LH receptor, StAR, and P450 aromatase, while mRNA levels of FSH receptor remained unchanged. Western blot analysis was consistent with the results of quantitative real-time RT-PCR assay. In addition, progesterone secretion was induced by the treatment of resveratrol.ConclusionsThese results suggest a novel mechanism that resveratrol could enhance progesterone secretion and expression of luteinization-related genes in the ovary, and thus provide important implications to understand the mechanism of luteal phase deficiency.

An hGCN5/TRRAP Histone Acetyltransferase Complex Co-activates BRCA1 Transactivation Function through Histone Modification

It is well established that genetic mutations that impair BRCA1function predispose women to early onset of breast and ovariancancer. However, the co-regulatory factors that support normalBRCA1 functions remain to be identified. Using a biochemicalapproach to search for such co-regulatory factors, we identifiedhGCN5, TRRAP, and hMSH2/6 as BRCA1-interacting proteins.Genetic mutations in the C-terminal transactivation domain ofBRCA1, as found in breast cancer patients (Chapman, M. S., andVerma,I.M.(1996)

BRCA1 function mediates a TRAP/DRIP complex through direct interaction with TRAP220

Breast cancer susceptibility gene 1 (BRCA1) is a tumor suppressor gene mutated in a high percentage of hereditary breast and ovarian cancers. The multifunctional BRCA1 protein acts on cell cycle control, exerting several highly specialized DNA repair processes through diverse domains. Gene regulation through its C-terminal domain (BRCT) is indispensable for BRCA1-mediated tumor suppression, suggesting the possibility that the BRCT domain interacts with co-regulator complexes. Using a biochemical approach with HeLa S3 nuclear extracts, we isolated BRCT-associated complexes and identified one of the purified components as TRAP220. We then performed interaction studies in vivo (co-immunoprecipitation) and in vitro (glutathione S-transferase pull-down assays) and showed that BRCT directly interacted with TRAP220. This in vitro interaction was completely abolished by BRCT point mutations typical of those found in patients with BRCA1 that lack transactivation function. BRCA1 transactivation function was dependent on TRAP220 expression level in a transient expression assay. Moreover, a cell survival assay showed that antisense TRAP220 expression to disrupt endogenous TRAP220 expression significantly reduced the survival rate potentiated by BRCA1 after DNA damage. These results suggested that a TRAP220 complex play an important role as putative co-activator complexes in BRCA1-mediated tumor suppression.

Conjoined twins in a triplet pregnancy after intracytoplasmic sperm injection and blastocyst transfer: case report and review of the literature

OBJECTIVE To describe an exceptional case of conjoined twins in a triplet pregnancy after intracytoplasmic sperm injection (ICSI) and blastocyst transfer. DESIGN Case report. SETTING University teaching hospital reproductive endocrinology department and infertility practice. PATIENT(S) A 34-year-old woman underwent ICSI and received two blastocysts transferred. INTERVENTION(S) Transvaginal ultrasonography performed sequentially during early pregnancy. MAIN OUTCOME MEASURE(S) Ultrasound images of the fetus in gestational sac. RESULT(S) Two gestational sacs in the uterus were revealed at the 5th week. At the 8th week of gestation, a single fetus was seen in one sac, whereas thoracopagus conjoined twins was diagnosed in the other sac. At the 10th week, the conjoined twins had a spontaneous cardiac arrest confirmed by color Doppler. The subsequent course was uneventful, and a healthy child was born at 39th week. CONCLUSION(S) To date, a small number of cases of conjoined twins in IVF/ICSI pregnancies have been reported, in which most cases were treated with manipulations causing possible trauma in the zona pellucida. Our case is unique in that the transferred embryos were blastocysts that might have had additional damage on the zona pellucida from the longer culture.

Repressive domain of unliganded human estrogen receptor alpha associates with Hsc70.

Estrogen receptor (ER) is a hormone‐inducible transcription factor as a member of the nuclear receptor gene superfamily. Unliganded ER is transcriptionally silent and capable of DNA binding; however, it is unable to suppress the basal activity of the target gene promoters, unlike non‐steroid hormone receptors that associate with corepressors in the absence of their cognate ligands. To study the molecular basis of how unliganded human ERα is maintained silent in gene regulation upon the target gene promoters, we biochemically searched interactants for hERα, and identified heat shock protein 70 (Hsc70). Hsc70 appeared to associate with the N‐terminal hormone binding E domain, that also turned out a transcriptionally repressive domain. Competitive association of Hsc70 with a best known coactivator p300 was observed. Thus, these findings suggest that Hsc70 associates with unliganded hERα, and thereby deters hERα from recruiting transcriptional coregulators, presumably as a component of chaperone complexes.

SIRT3 positively regulates the expression of folliculogenesis- and luteinization-related genes and progesterone secretion by manipulating oxidative stress in human luteinized granulosa cells.

SIRT3 is a member of the sirtuin family and has recently emerged as a vital molecule in controlling the generation of reactive oxygen species (ROS) in oocytes. Appropriate levels of ROS play pivotal roles in human reproductive medicine. The aim of the present study was to investigate SIRT3 expression and analyze the SIRT3-mediated oxidative response in human luteinized granulosa cells (GCs). Human ovarian tissues were subjected to immunohistochemical analysis to localize SIRT3 expression. Hydrogen peroxide and human chorionic gonadotropin were used to analyze the relationship between ROS and SIRT3 by quantitative RT-PCR and Western blotting. Intracellular levels of ROS were investigated by fluorescence after small interfering RNA-mediated knockdown of SIRT3 in human GCs. To uncover the role of SIRT3 in folliculogenesis and luteinization, mRNA levels of related genes and the progesterone concentration were analyzed by quantitative RT-PCR and immunoassays, respectively. We detected the expression of SIRT3 in the GCs of the human ovary. The mRNA levels of SIRT3, catalase, and superoxide dismutase 1 were up-regulated by hydrogen peroxide in both COV434 cells and human GCs and down-regulated by human chorionic gonadotropin. Knockdown of SIRT3 markedly elevated ROS generation in human GCs. In addition, SIRT3 depletion resulted in decreased mRNA expression of aromatase, 17β-hydroxysteroid dehydrogenase 1, steroidogenic acute regulatory protein, cholesterol side-chain cleavage enzyme, and 3β-hydroxysteroid dehydrogenase in GCs and thus resulted in decreased progesterone secretion. These results have the important clinical implication that SIRT3 might play a positive role in the folliculogenesis and luteinization processes in GCs, possibly by sensing and regulating the generation of ROS. Activation of SIRT3 function might help to sustain human reproduction by maintaining GCs as well as oocytes.

Regulation of SIRT1 determines initial step of endometrial receptivity by controlling E-cadherin expression.

Sirtuin 1 (SIRT1), originally found as a class III histone deacetylase, is a principal modulator of pathways downstream of calorie restriction, and the activation of SIRT1 ameliorates glucose homeostasis and insulin sensitivity. We examined the role of SIRT1 in the regulation of uterine receptivity using Ishikawa and RL95-2 endometrial carcinoma cell lines. Exogenous expression of SIRT1 significantly enhanced E-cadherin expression, while small interfering RNA-mediated depletion of endogenous SIRT1 resulted in a significant reduction of E-cadherin expression. A SIRT1 activator resveratrol elevated E-cadherin expression in a dose dependent manner, while SIRT1 repressors nicotinamide and sirtinol exhibited a dose dependent reduction of E-cadherin expression. We also showed that both forced expression of SIRT1 and activation of SIRT1 promote E-cadherin-driven reporter gene constructs, and SIRT1 is localized at E-cadherin promoter containing E-box elements in Ishikawa cells. Using an in vitro model of embryo implantation, we demonstrate that exogenous expression of SIRT1 and stimulation of SIRT1 activity resulted in the Ishikawa cell line becoming receptive to JAR cell spheroid attachment. Furthermore, resveratrol enhanced E-cadherin and Glycodelin protein expression at sites of intercellular contact, suggesting an additive role of resveratrol in promoting implantation. The initial step of human reproduction depends on the capacity of an embryo to attach and implant into the endometrial wall, and these results revealed the novel mechanism that activation and increased expression of SIRT1 play an important role in uterine receptivity.

Spontaneous cessation and recurrence of massive uterine bleeding can occur in uterine artery pseudoaneurysm after laparoscopically assisted myomectomy

A uterine artery pseudoaneurysm (UAP) is a rare but life‐threatening complication that can occur after gynecologic surgery. Herein, we present a case of a 38‐year‐old woman who presented with massive uterine bleeding one month after a laparoscopically assisted myomectomy. Although the bleeding ceased spontaneously, a massive hemorrhage reoccurred three weeks thereafter, and a ruptured perfusion sac at the right uterine artery was identified by computed tomography angiography and ultrasonography. The patient was treated with transfemoral catheter embolization of the right uterine artery, and complete resolution of the UAP was successfully obtained. Our case suggests that a UAP may be a cause of unexplained repetitive metrorrhagia after myomectomy.

The Emerging Role of FOXL2 in Regulating the Transcriptional Activation Function of Estrogen Receptor β: An Insight Into Ovarian Folliculogenesis.

Germline mutations of the fork-head transcriptional factor forkhead box L2 (FOXL2) predispose embryos to autosomal-dominant blepharophimosis–ptosis–epicanthus inversus syndrome with primary ovarian insufficiency in female patients, but the mechanisms of FOXL2 in ovarian follicular development remain elusive. Estrogens produced by ovarian granulosa cells and estrogen receptor (ER) α and ERβ play fundamental roles in ovarian pathophysiology, and a previous study revealed that ERα and ERβ physically interact with FOXL2. However, the underlying functions of these interactions have not been investigated. Herein, we report an ERβ-specific repressive function of FOXL2. Histological examination demonstrated that FOXL2 expression tends to be intense during early follicular development. Immunoprecipitation revealed that ERβ and FOXL2 interact in a ligand-independent manner. In vitro pull-down assays revealed a direct interaction between FOXL2 and the activation function (AF)-1/2 domain of ERβ. The expression of FOXL2 represses the ligand-dependent transcriptional activation of ERβ, but FOXL2 does not influence the ligand-dependent transcriptional activation of ERα. Consistent with these results, RNA interference-mediated depletion of FOXL2 stimulates the expression of the ERβ-downstream gene p450 aromatase. The convergence between FOXL2 functions and ERβ-mediated transcription in the ovary suggests the putative mechanism of FOXL2 in early-phase follicular development, which may be partially attributed to the regulation of ERβ-dependent gene expression.