Biomedical subjects

Yin-Chuan Li

Publications and source records attributed to Yin-Chuan Li.

10 recordsLinked to original sources

PubMed2006

Heat treatment induces liver receptor homolog-1 expression in monkey and rat sertoli cells.

We demonstrated in this study that liver receptor homolog-1 (LRH-1) was expressed in the round spermatids in normal monkey testis, and no LRH-1 signal was observed in the Sertoli cells. After local warming (43 C) the monkey testis, however, LRH-1 expression was induced in the Sertoli cells in coincidence with activation of cytokeratin 18 (CK-18), a Sertoli cell dedifferentiated marker. Furthermore, we isolated rat primary Sertoli cells from testes at various stages of development and treated with 43 C water in vitro. The changes in LRH-1 as well as CK-18 expression were analyzed by confocal immunohistochemistry and Western blot. The results showed that LRH-1 was stage-dependently expressed in the Sertoli cells; no LRH-1-positive signal was detected in the cells obtained from the testes of adult rat on d 60 after birth when mature spermatozoa in the testis was completed. However, the mature Sertoli cells were warmed at the 43 C water bath for 15 min, and the LRH-1 signal was remarkably induced in a time-dependent manner, just like the changes of CK-18 expression in the Sertoli cells, suggesting that the heat-induced dedifferentiation of the mature Sertoli cells might be related to LRH-1 regulation. LRH-1 expression induced by the heat treatment was completely inhibited by the addition of ERK inhibitor U0126 in the culture, indicating that the heat-induced LRH-1 expression in the Sertoli cells may be regulated via ERK1/2 activation pathway. Testosterone was found to have no such effect on LRH-1 expression in the monkey and rat Sertoli cells.

Animals↗

PubMed2006

An oligonucleotide microarray study on gene expression profile in mouse testis of experimental cryptorchidism.

To investigate the germ cell apoptosis under body temperature in testis, we analyzed the gene expression patterns on day 1, day 4, day 7, day 14, day 28 and normal control adult mouse testis after experimental cryptorchidism (EC) using Affymetrix MOE430A microarray. Our data showed that EC led to the oxidative stress and gene expression fluctuation in the first 28 days, both of which were highly coincident in timing. Cryptorchid testis showed more effective antioxidative capability in the first 4 days, and suddenly lowered the capability from day 5 on, then gradually restored the antioxidation from day 10 to day 14, and turned to worse on day 28 again. The extensive high gene expression on day 4 after EC and the up-rising of oxidative stress level on day 5 and the abrupt down-regulation of the gene on day 7 were closely related. From the chip data, we have found that the high level of reactive oxidative species (ROS) was not only related to the dysfunction or abnormality of the direct origin of ROS generation, but also related to the abnormality of the more upstream physiological events in energy metabolism, lipid metabolism. The selective regulation of metabolic substrate transporter in different cell population implied the existence of various regulation of the selective signal pathways among different cell populations by EC.

Animals↗

PubMed2006

Afaf, a novel vesicle membrane protein, is related to acrosome formation in murine testis.

As a cell-specific organelle, acrosome (Acr) and its formation are an important event for spermiogenesis. However, the Acr formation is far more complicated than has been proposed. In this study, we have cloned a novel membrane protein Afaf (Acr formation associated factor) that was expressed abundantly in the round spermatids, localized in the inner and outer membrane of forming Acrs, and declined in the maturing Acrs. In the transfected Hela cells, Afaf protein was localized in the plasma membrane, EEA1-positive early endosomes (EEs) and occasionally in the nuclei. Therefore, we propose that EEs and plasma membrane may be also directly involved in the Acr biogenesis.

3T3 Cells↗

PubMed2006

The expression of membrane protein augments the specific responses induced by SARS-CoV nucleocapsid DNA immunization.

Nucleocapsid protein plays a critical role in SARS-CoV pathogenesis, and high-level anti-nucleocapsid antibodies are detected in the patients infected by severe acute respiratory syndrome-associated coronavirus (SARS-CoV). Several studies have shown that there exists an interaction between nucleocapsid (N) and membrane (M) protein. In this paper, we investigate whether the expression of membrane protein can affect the immune responses induced by nucleocapsid DNA immunization. Two recombinant plasmids containing M and N coding sequence were constructed. Moreover, in order to get the antigen for ELISA and in vitro stimulation assay, N protein were expressed and purified from E. coli bacteria. Injection of 20mug of the mixture of pVAX1-M and pVAX1-N into the Balb/c mice could elicit the humoral and cellular responses. The ELISA analysis using the N antigen or inactivated SARS-CoV particles as capture antigen showed that co-injection of SARS-M could enhance N-induced antibody production, especially IgG2a subclass. After lymphocytes were stimulated with 10mug/ml purified N antigen, The CD4+ and CD8+ T cells of N and M plus N group were increased compared with those of control groups, and the M protein could augment the activation of lymphocytes induced by N DNA vaccine. Cytokine ELISA analysis revealed that co-injection of M could enhance the levels of IFN-gamma, IL-2 release induced by N antigen. Further experiments in field mouse also support the claim that membrane protein can augment the N-specific immune responses. Virus challenge test was conducted in BSL3 bio safety laboratory with Brandt's vole SARS-CoV model, and the results indicated that co-immunization of M and N antigens could reduce the mortality and pathological changes in lung from the virus infection.

Animals↗

PubMed2006

Cloning and characterization of a novel spermiogenesis-related gene, T6441, in rat testis.

We report in the present study the cloning and characterization of a novel gene, named T6441, initially derived by the suppressive subtracted hybridization (SSH) cDNA library. The full-length T6441cDNA was 664 bp long, containing a complete open-reading frame for a protein of 149 amino acids (aa). The protein bears no homology to any reported genes. It is predicted that the molecular mass was about 16.7 kDa. Northern blot analysis showed that the T6441 gene had about 4 transcripts in adult rat testis and was temporally regulated in a stage-dependent manner in the testis. In situ hybridization showed that T6441 mRNA was specifically localized in spermatids, and its expression level varied in the cells at different stages of the testicular development, with the highest level at steps 7-14. RT-PCR results showed that the T6441 mRNA was transcribed in most of the tested tissues with its strongest signal in the testis. Recombinant T6441 protein was prepared, purified, and was used to raise rabbit. Western blot analysis using the antiserum revealed four possible testicular specific proteins with their molecular weights being about 22, 25, 50 and 55 kDa respectively. The T6441 protein was expressed mainly in the cytoplasm of spermatids with the maximal levels at steps 12-19. At step 19 spermatid, the T6441 was mainly localized in the residual bodies. The cytoplasm localization of T6441 protein was supported by transient over expression of GFP-fusion protein in Hela cells. Interestingly, the expression of T6441 caused death of transfected cells within 48 h. Our preliminary experimental results suggest that the T6441 gene may play a role in cytoplasm movement and removal during spermiogenesis.

Amino Acid Sequence↗

PubMed2006

Expression and regulation of stanniocalcin 1 and 2 in rat uterus during embryo implantation and decidualization.

Stanniocalcin-1 (STC-1) is a recently discovered polypeptide hormone, while stanniocalcin-2 (STC-2) is a subsequently identified homologue of stanniocalcin-1. Although previous studies have shown that both STC-1 and -2 are involved in various physiological processes, such as ion transport, reproduction and development, their expression in the uterus and roles in implantation and early pregnancy are unclear. Here we have investigated the expression and regulation of both STC-1 and STC-2 in rat uterus during early pregnancy under various physiological conditions. We show that only basal levels of STC-1 and STC-2 mRNA were detected in the uterus from day one (D1) to day five (D5) of pregnancy. STC-2 immunostaining was gradually increased in the glandular epithelium from day two (D2), with a peak occurring on D5. High levels of both STC-1 and STC-2 mRNA were observed in the stoma cells at the implantation site on day six (D6) of pregnancy, whereas their immunostaining signals were also significant in the luminal epithelium. Basal levels of both STC-1 and STC-2 mRNA and STC-1 immunostaining were detected in the uterus with delayed implantation. After the delayed implantation was terminated by estrogen treatment, both STC-1 and STC-2 mRNA signals were significantly induced in the stroma underlying the luminal epithelium at the implantation site, and STC-2 immunostaining was also observed in the luminal epithelium surrounding the implanting blastocyst. Embryo transfer experiments further confirmed that STC-1 and STC-2 expression at the implantation sites was induced by the implanting blastocyst. Both STC-1 mRNA and immunostaining were seen in the decidualized cells from day seven (D7) to day nine (D9) of pregnancy. STC-2 mRNA was also found in the whole decidua from D7 to D9 of pregnancy; STC-2 protein, however, was strictly localized to the primary deciduas on D7 and D8, with a weak expression in the whole deciduas on D9. Consistent with the normal pregnancy process, strong STC-1 and STC-2 mRNA signals were detected in the decidualized cells under artificial decidualization, whereas only basal levels of STC-1 mRNA and immunostaining were observed in the control horn. These data suggest, for the first time, that STC-1 together with STC-2 may play important roles in the processes of implantation and decidualization in the rat.

Animals↗

PubMed2005

Transient testicular warming enhances the suppressive effect of testosterone on spermatogenesis in adult cynomolgus monkeys (Macaca fascicularis).

CONTEXT: The context of the study was to examine whether combined testosterone (T) and heat (H) treatment have additive or synergistic effects on suppression of spermatogenesis. OBJECTIVE: The objective of the study was to determine whether T+H induces a greater suppression of spermatogenesis than either treatment alone in monkeys. DESIGN: The study was a randomized, placebo-controlled study. SETTING: The study was conducted at a primate center in China. PARTICIPANTS: The study population was comprised of 32 adult cynomolgus monkeys. INTERVENTIONS: Groups of eight adult monkeys were treated for 12 wk with: 1) two empty implants (C); 2) two T implants (T); 3) daily testicular heat exposure (43 C for 30 min) for 2 consecutive days (H); or 4) two T implants plus testicular heat exposure (T+H). Treatment was followed by an 8-wk recovery period. MAIN OUTCOME MEASURES: Measures included sperm counts and germ cell apoptosis. RESULTS: Serum T levels were elevated in both the T and T+H groups during treatment but not in the C or H group. Sperm counts were transiently suppressed after heat to 16.4% of baseline at 4 wk and then returned to pretreatment levels. Sperm counts were suppressed slowly after T treatment to nadir of 6.4% of pretreatment levels at 12 wk. T+H rapidly suppressed sperm output as early as 4 wk to 3.9% of pretreatment levels that was maintained throughout treatment. The decreased sperm counts were due to increased germ cell apoptosis in all treatment groups. Sperm counts recovered to the pretreatment levels in all groups by 8 wk after treatment. CONCLUSION: This proof-of-concept study demonstrates that transient testicular warming enhances and hastens the effect of T implant on the suppression of spermatogenesis in monkeys.

Animals↗

PubMed2005

Extracellular Ca2+-sensing receptor expression and hormonal regulation in rat uterus during the peri-implantation period.

The extracellular Ca2+-sensing receptor (CaR) is a member of the superfamily of G protein-coupled receptors (GPCRs). It is an important mediator of a wide range of Ca2+-dependent physiological responses in various tissues. In reproductive tissues it has been reported to play a significant role in promoting or maintaining placentation. Meanwhile, another Ca2+ regulated gene stanniocalcin-1 (STC-1) has been documented to be involved in decidualization and uterine remodelling. The phenomenon that CaR mediates STC-1's transcription responding to extracellular calcium in fish urges us to suppose that CaR, like STC-1, may also play a role in implantation and decidualization. To resolve this conjecture, we have examined the expression and hormonal regulation of the CaR gene in rat uterus during peri-implantation period. CaR mRNA was expressed at a moderate level in the luminal epithelium of the early stage of pregnancy (from day 1 to day 3). From day 2-3 it began to be expressed more strongly in the stromal cells immediately underneath the luminal epithelium, but decreased to a basal level on day 4. From day 6 to day 9 continuously, both CaR mRNA and protein were highly expressed in the primary decidua. Expression of CaR mRNA and protein in these cells was also observed when a delayed implantation was terminated by estrogen treatment to allow the embryo implantation. In contrast, only basal level expression of the molecules was detected in the cells of animals subjected to a normal-delayed implantation or the pseudopregnant condition. Embryo transplantation experiment confirmed that CaR expression at the implantation site was induced by the implanting blastocyst. Consistent with the normal pregnant process, CaR mRNA and protein in the cells were also induced by an artificial decidualization procedure. Further experiments demonstrated that treatment of the ovariectomized rat with estrogen or/and progesterone stimulated a high level expression of CaR mRNA in the uterine epithelial and glandular epithelium. In conclusion, CaR was specifically induced during the processes of implantation and subsequent decidualization and may play a role in these processes.

Animals↗

PubMed2003

Tissue-type plasminogen activator and its inhibitor plasminogen activator inhibitor type 1 are coordinately expressed during ovulation in the rhesus monkey.

Ovulation is a gonadotropin-controlled process that is essential for the propagation of all mammalian species. In the present study, we used a pregnant mare serum gonodotropin/human chorionic gonadotropin (hCG)-induced, synchronized ovulation model in rhesus monkeys and systematically investigated the roles of the plasminogen activator (PA) system in the ovulatory process of the primate. At different follicular developmental stages throughout the periovulatory period, samples of ovaries, granulosa cells, and theca-interstitial cells as well as follicular fluid were collected, and levels of PA and PA inhibitor type-1 (PAI-1) were evaluated by fibrin overlay, reverse fibrin overlay, Northern blot analysis, and in situ hybridization, respectively. We showed that in response to an injection of ovulation-triggering hCG, which mimics the preovulatory surge of LH in the circulation, granulosa cell-derived tissue-type PA (tPA) was substantially elevated in preovulatory follicles and reached its maximum level just before ovulation. Although theca-interstitial cell-derived PAI-1 was also stimulated by pregnant mare serum gonodotropin and hCG treatments, however, the maximum level of PAI-1 appeared 12 h earlier than that of tPA. When ovulation approached, accompanying the highest tPA level in the preovulatory follicles, the follicular PAI-1 level declined dramatically to its minimum value. Moreover, our data on the expression of follicular PA and PAI-1 over the periovulatory period were reinforced by results obtained at the mRNA level. Our data suggest that the coordinated expression of tPA and PAI-1 may be of importance for the follicular rupture process during ovulation in the primate.

Aging↗

PubMed2003

Expression and regulation of plasminogen activators, plasminogen activator inhibitor type-1, and steroidogenic acute regulatory protein in the rhesus monkey corpus luteum.

The corpus luteum (CL) is a transient endocrine organ that secretes progesterone to support early pregnancy. Using primate materials obtained from rhesus monkeys, we have in this study investigated the expression and regulation of the plasminogen activators (PAs) and PA inhibitor type 1 (PAI-1) during CL development and regression. Adult (5-7 yr old) female rhesus monkeys were treated with pregnant mare serum gonadotropin/human chorionic gonadotropin to induce ovulation and follicular luteinization. At various luteal developmental stages, CL or whole ovaries were obtained for preparing luteal cells, Northern blot, in situ hybridization, and immunohistochemistry. We demonstrated that luteal cells from the rhesus monkey were able to produce both tissue type PA (tPA) and urokinase type PA, as well as the physiological PAI-1. During luteal development in the monkey, urokinase type PA was the major PA species taking part in the active angiogenesis and tissue remodeling processes in the forming CL. However, the mRNA as well as the enzymatic activity levels of tPA increased dramatically in monkey CL with the advent of luteolysis. This change of tPA levels was in a temporal coordination with the regulation of PAI-1 expression, resulting in an increased tPA activity at the initiation of luteolysis. Therefore, we suggest that tPA might be a luteolytic factor to the monkey CL. A PAI-1 modulated tPA activity might be important for the initiation of luteolysis in the monkey. In addition, we have also demonstrated that the expression of steroidogenic acute regulatory protein in the monkey CL was in accordance with the changes of progesterone production, suggesting that steroidogenic acute regulatory protein expression may be considered as a reliable marker for CL function in primates.

Animals↗