Biomedical subjects

Ruijin Shao

Publications and source records attributed to Ruijin Shao.

8 recordsLinked to original sources

PubMed2006

Induction of apoptosis increases SUMO-1 protein expression and conjugation in mouse periovulatory granulosa cells in vitro.

The small ubiquitin-related modifier-1 (SUMO-1) with broad cellular expression has been implicated in a range of cellular processes, such as cell proliferation, differentiation, and apoptosis. As shown recently, SUMO-1 is expressed and regulated by gonadotropins, in particular an ovulatory hCG stimulus in mouse granulosa cells in vivo. To test the hypothesis that modulation of granulosa cell apoptosis changes SUMO-1 expression during granulosa cell differentiation in the mouse ovary, we demonstrate that progesterone receptor (PR) proteins are absent in pre-ovulatory granulosa cell nuclei, whereas they are expressed in periovulatory granulosa cell nuclei in parallel with decreases in SUMO-1 expression, caspase-3 activation, and DNA fragmentation in vivo. Second, treatment with either PR antagonists or a cell permeable ceramide analog consistently increases SUMO-1 expression in parallel with an increase in apoptosis as well as a decrease in cell proliferation in periovulatory granulosa cells in vitro. However, we do not observe an increase in SUMO-1 expression in pre-ovulatory granulosa cells that have undergone the same treatment. Third, we have also demonstrated, in pre-ovulatory granulosa cells in vitro, neither induction of spontaneous apoptosis nor the protective effect of EGF against spontaneous apoptosis changes SUMO-1 protein expression. Fourth, we show that induction of apoptosis enhances SUMO-1 conjugation in periovulatory granulosa cells in vitro, pointing to the pivotal link between the SUMO-1 conjugation and cell death. Taken together, our observations suggest that SUMO-1 via sumoylation has an important role in the regulation of granulosa cell apoptosis during granulosa cell differentiation in the mouse ovary.

Animals↗

PubMed2004

Progesterone-receptor antagonists and statins decrease de novo cholesterol synthesis and increase apoptosis in rat and human periovulatory granulosa cells in vitro.

Progesterone-receptor (PR) stimulation promotes survival in rat and human periovulatory granulosa cells. To investigate the mechanisms involved, periovulatory rat granulosa cells were incubated in vitro with or without the PR-antagonist Org 31710. Org 31710 caused the expected increase in apoptosis, and expression profiling using cDNA microarray analysis revealed regulation of several groups of genes with functional and/or metabolic connections. This regulation included decreased expression of genes involved in follicular rupture, increased stress responses, decreased angiogenesis, and decreased cholesterol synthesis. A decreased cholesterol synthesis was verified in experiments with both rat and human periovulatory granulosa cells treated with the PR-antagonists Org 31710 or RU 486 by measuring incorporation of [14C]acetate into cholesterol, cholesterol ester, and progesterone. Correspondingly, specific inhibition of cholesterol synthesis in periovulatory rat granulosa cells using 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (lovastatin, mevastatin, or simvastatin) increased apoptosis, measured as DNA fragmentation and caspase-3/7 activity. The increase in apoptosis caused by simvastatin was reversed by addition of the cholesterol synthesis-intermediary mevalonic acid. These results show that PR antagonists reduce cholesterol synthesis in periovulatory granulosa cells and that cholesterol synthesis is important for granulosa cell survival.

Animals↗

PubMed2004

Increase of SUMO-1 expression in response to hypoxia: direct interaction with HIF-1alpha in adult mouse brain and heart in vivo.

The present study investigates the regulation of small ubiquitin-related modifier-1 (SUMO-1) expression in response to hypoxia in adult mouse brain and heart. We observed a significant increase in SUMO-1 mRNAs and proteins after hypoxic stimulation in vivo. Because SUMO-1 interacts with various transcription factors, including hypoxia-inducible factor-1beta (HIF-1beta) in vitro, we not only demonstrated that the HIF-1alpha expression is increased by hypoxia in brain and heart, but also provided evidence that SUMO-1 co-localizes in vivo with HIF-1alpha in response to hypoxia by demonstrating the co-expression of these two proteins in neurons and cardiomyocytes. The specific interaction between SUMO-1 and HIF-1alpha was additionally demonstrated with co-immunoprecipitation. These results indicate that the increased levels of SUMO-1 participate in the modulation of HIF-1alpha function through sumoylation in brain and heart.

Animals↗

PubMed2003

Inhibition of small ubiquitin-related modifier-1 expression by luteinizing hormone receptor stimulation is linked to induction of progesterone receptor during ovulation in mouse granulosa cells.

The small ubiquitin-related modifier-1 (SUMO-1) is a member of a family of ubiquitin-related proteins that have effects on several important physiological functions, including reproduction. However, the regulation of SUMO-1 expression and functional distribution of SUMO-1 in vivo remain poorly understood. In the present study, we show that SUMO-1 protein is widely expressed in various tissues. In the ovary, the expression of SUMO-1 protein is suppressed around ovulation, in both the whole ovary and the granulosa cells, after gonadotropin treatment. Additionally, when the ovulatory signal, the endogenous LH surge, is blocked in vivo by pentobarbitone sodium, the expression of SUMO-1 protein in granulosa cells is increased. This effect is reversed when the missing endogenous LH surge is substituted by human chorionic gonadotropin treatment. Our findings provide the first evidence that inhibition of SUMO-1 expression is regulated by LH receptor stimulation in granulosa cells concomitant with ovulation in the mouse ovary. Furthermore, the levels of SUMO-1 protein are increased in granulosa cells treated with progesterone receptor (PR) antagonists both in vivo and in vitro, demonstrating that SUMO-1 expression is regulated by functional PR. SUMO-1 interacts with nuclear receptors in vitro, and LH receptor-mediated induction of PR is crucial for ovulation. SUMO-1 and PR are coexpressed and can be coprecipitated, providing additional evidence for a direct interaction between SUMO-1 and PR in periovulatory granulosa cells in vivo. These results suggest that a functional link between SUMO-1 and PR is of physiological importance for the local modulation of PR-mediated events in the ovary.

Animals↗

PubMed2003

Gene expression analysis of prostate hyperplasia in mice overexpressing the prolactin gene specifically in the prostate.

The probasin (Pb)-PRL transgenic mice that overexpress the rat PRL gene specifically in the prostate develop a dramatic enlargement of the prostate gland. The objective of this study was to characterize the molecular mechanisms involved in the prostate hyperplasia seen in the Pb-PRL transgenic mice. cDNA microarray analysis was used to identify differentially expressed transcripts in the hyperplastic prostates of 6-month-old transgenic mice compared with age-matched controls. We report the identification of 266 genes (175 up-regulated and 91 down-regulated) that were differentially expressed in the enlarged transgenic prostates compared with controls. Subsequential real-time RT-PCR was used to verify a set of differentially regulated transcripts. The hyperplastic prostates of Pb-PRL transgenic mice demonstrate a molecular pattern supporting the importance of reduced degree of apoptosis for the development of the phenotype. Immunohistochemical analysis of apoptotic activity using two different markers of apoptosis (single-stranded DNA and activated caspase-3) were performed, and the results showed diminished apoptosis activity in the prostate of Pb-PRL transgenic mice compared with control prostates. The increased stromal/epithelial ratio of the Pb-PRL transgenic prostate together with up-regulation of a significant fraction of genes involved in tissue remodeling activity, including the synthesis and degradation of the extracellular matrix and changes in protease activity, suggest that activation of the stroma is involved in the development of prostate hyperplasia. Overall, the differentially expressed transcripts identified in this study show many molecular similarities between the prostate hyperplasia of PRL-transgenic mice and human prostate pathology, including both benign prostatic hyperplasia and prostate cancer.

Androgen-Binding Protein↗

PubMed2003

Suppression of apoptosis occurs in the cochlea by sound conditioning.

Apoptosis plays a critical role in the pathogenesis of noise-induced hearing loss. The goal of this study was to determine if apoptotic pathways are suppressed by sound conditioning. Sound conditioning is a pretreatment to low-level non-damaging sound that protects against a subsequent damaging acoustic trauma. Sound conditioning protects against hair cell death and thereby preserves hearing after a subsequent acoustic trauma. Using a combination of immunocytochemical and Western blotting techniques we show that acoustic trauma causes the release of cytochrome c from the mitochondria into the cytoplasm, and a decrease in bcl-2 immunoreactivity in the outer hair cells. Sound conditioning was found to trigger a protection against these detrimental changes. These data suggest that bcl-2 plays an important role in the regulation of hair cell death, and provides evidence that bcl-2 acts as an inducible neuroprotective gene that is upregulated by sound conditioning.

Acoustic Stimulation↗

PubMed2003

Expression of progesterone receptor (PR) A and B isoforms in mouse granulosa cells: stage-dependent PR-mediated regulation of apoptosis and cell proliferation.

The intracellular progesterone receptor (PR) in the mammalian ovary is a part of the physiological pathway that facilitates ovulation. Two PR isoforms (A and B) exist, with different molecular and biological functions. Previous studies have revealed that the cellular ratio of the PR isoforms is important for progesterone-responsive tissues and is under developmental control in different species. However, the relative expression of PR isoforms in the ovary is unknown. In this study we have demonstrated first that the expression of both PR isoforms in mouse granulosa cells was rapidly up-regulated by hCG treatment and dramatically down-regulated when the granulosa cells were undergoing luteinization. The relative level of protein expression of the A and B forms was 2:1 and the highest total PR protein expression was found after hCG stimulation. Second, we demonstrated that the expression of PR protein was specific to granulosa cells of periovulatory follicles and was absent in undifferentiated granulosa cells of growing follicles. It was not detected in other cell types (i.e., corpora lutea or any stage of follicles with features of apoptosis). Third, we demonstrated that treatment with the PR antagonist RU 486 in vivo resulted in down-regulation of both isoforms in parallel with increased activation of caspase-3, a decreased level of proliferating cell nuclear antigen, and a reduced rate of ovulation. Fourth, we demonstrated, in vitro, that the PR antagonists RU 486 and Org 31710 increased internucleosomal DNA fragmentation parallel with a decrease in DNA synthesis in granulosa cells, which express PR. These results indicate that PR and its isoforms participate in regulation of ovulation, along with suppression of granulosa cell apoptosis and promotion of cell survival in the mouse ovary.

Animals↗

PubMed2002

Survival factors regulating ovarian apoptosis -- dependence on follicle differentiation.

Only a minute fraction of the ovarian follicles present in a fetal ovary will complete the path to ovulation. Most of the follicles will undergo atresia, a hormonally controlled apoptotic process. Apoptosis occurs at each stage of follicular development and there is a marked reduction in the number of follicles present at birth. Stage-dependent mechanisms of follicle survival can be postulated to achieve co-ordinated development, leading to ovulation of a small fraction of follicles. Indeed, hormone and growth factor regulation of follicular atresia is stage-specific. This short review considers the factors that promote survival of ovarian follicles throughout development, including endocrine, locally produced and intracellular mediators, as exemplified mainly by follicular development in rodents. In primordial follicles, oocyte apoptosis is considered to be the cause of subsequent follicle degeneration. In slow-growing preantral follicles, FSH is not a survival factor, but some locally produced growth factors are. Progression to the antral follicle stage is probably the most critical stage of follicle development in vivo, and FSH is a major survival factor at this stage. In addition, insulin-like growth factor I and interleukin 1beta are potent survival factors for cultured rat follicles at the antral stage. Preovulatory follicles express receptors for LH, and both of the gonadotrophins are survival factors at this stage. Relatively little is known about the period between the LH surge and ovulation; however, it has been suggested that at this stage progesterone acts as a survival factor.

Animals↗