LH/CG受体基因克隆与表达的研究进展

LH/CG受体是一种与G蛋白偶联的在哺乳动物生殖及性功能调节起重要作用的糖蛋白激素受体。介绍了鼠、猪及人等哺乳动物、鸟类、鱼类LH/CG受体基因及昆虫,无脊椎动物等LH/CG类受体的基因克隆表达及特性。     

Efficiency of superstimulatory protocol P-36 associated with the administration of eCG and LH in Nelore cows

Recent work with P-36 demonstrates that the replacement of the last two doses of Follicle-Stimulating Hormone (FSH) with equine chorionic gonadotropin (eCG) increases embryo yields. However, it is unclear if the positive effect of eCG is related to its FSH-like activity, LH-like activity, or both. This study aimed to verify the replacement of eCG with pLH on the last day of superstimulatory treatment. Twenty-five Nelore cows were allocated to four groups: P-36 (control), P-36/eCG, P-36/LH2, and P-36/LH4. All animals underwent four treatments in a crossover design. The control group cows were superstimulated with decreasing doses of porcine Follicle-Stimulating Hormone (pFSH, 133 mg, im). In the P-36/eCG, P-36/LH2, and P-36/LH4 groups, the last two doses of pFSH were replaced in the former group by two doses of eCG (200 IU each dose, im) and in the latter two groups by two doses of pLH (1 and 2 mg each dose, im), respectively. Donors received fixed-time artificial insemination 12 and 24 hours after pLH. Embryo flushing was performed on D16. Data were analyzed by ANOVA (Proc Mixed, SAS). There was a trend of decreasing ovulation rate when comparing groups LH2 and eCG (P = 0.06). However, there was no significant difference in the mean number of viable embryos among groups P-36 (3.3 ± 0.7), P-36/eCG (4.5 ± 0.5), P-36/LH2 (3.7 ± 0.8), and P-36/LH4 (4.2 ± 1.0). It is concluded that the replacement of eCG by pLH on the last day of superstimulatory treatment can be performed with no significant variation in the production of viable embryos.     

Endometrial effects of selective estrogen receptor modulators (SERMs) on estradiol-responsive gene expression are gene and cell-specific

Three selective estrogen receptor modulator (SERM) drugs which included 4-OH-tamoxifen (Tam), EM-800 (EM) and GW 5638 (GW) were investigated to determine their ability to inhibit estradiol-responsive gene expression in sheep endometrium. The uteri of ovariectomized ewes (10 ewes per SERM group) were infused with 10⁻⁷ M SERMs for 24 h prior to hysterectomy. Five ewes from each group received 50 μg 17β-estradiol (E2) and the remaining five ewes received vehicle 18 h prior to hysterectomy. Northern blot analyses and in situ hybridization demonstrated that E2 treatment increased estrogen receptor (ER), progesterone receptor (PR), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and cyclophilin (CYC) mRNA levels in most endometrial cells examined. Tam and GW exhibited characteristics similar to E2 by increasing ER gene expression, but they antagonized the E2-induced increases in PR and CYC mRNA levels. EM acted as an E2-agonist of GAPDH gene expression, but antagonized the E2 up-regulation of ER, PR and CYC gene expression in most endometrial cells. Immunohistochemistry determined that EM decreased ER protein levels in the glandular epithelium, and the SERMs investigated antagonized increases in PR protein levels in endometrium. In conclusion, GW and EM exhibit fewer agonist effects than Tam on endometrial gene expression. EM demonstrated the greatest antagonism of E2-enhanced levels of ER, PR and CYC, likely due to the inhibition of ER gene expression at both mRNA and protein levels.     

Protein kinase activity of the insulin receptor is essential for insulin-regulated gene expression

Two Chinese hamster ovary (CHO) cell lines stably transfected with human insulin receptor cDNA, CHO-wt and CHO-mut, which express an equivalent number of normal and kinase-defective human insulin receptors, respectively, were used to assess the roles of insulin receptor tyrosine kinase activity in insulin-regulated gene expression. The effect of insulin on gene-33-promoter-driven chloramphenicol acetyltransferase (CAT), RSVLTR-driven -galactosidase (pRSVLTR-gal) and SV40 late-promoter-driven hepatitis B surface antigen (pMLSV₂HBsAg) were examined in CHO-wt and CHO-mut cells. Insulin-stimulated gene 33 promoter is 10- to 50-fold more effective in CHO-wt cells than that in parental CHO cells. However, no enhancement of insulin sensitivity of gene 33 promoter in CHO-mut cells relative to parental CHO cells was found. Similar phenomena were also observed, in that insulin regulated pRSVLTR-gal and pMLSV₂HBsAg in these three CHO lines. Our data indicated that the protein kinase activity of the insulin receptor is essential for the stimulatory activity of insulin toward the activities of different promoters.     

Aryl hydrocarbon receptor (AhR)-mediated reporter gene expression systems in transgenic tobacco plants

In mammals, the aryl hydrocarbon receptor (AhR) mediates expression of certain genes, including CYP1A1, in response to exposure to dioxins and related compounds. We have constructed a mouse AhR-mediated gene expression systems for a β-glucuronidase (GUS) reporter gene consisting of an AhR, an AhR nuclear translocator (Arnt), and a xenobiotic response element (XRE)-driven promoter in transgenic tobacco plants. On treatment with the AhR ligands 3-methylcholanthrene (MC), β-naphthoflavone (βNF), and indigo, the transgenic tobacco plants exhibited enhanced GUS activity, presumably by inducible expression of the reporter gene. The recombinant AhR (AhRV), with the activation domain replaced by that of the Herpes simplex virus protein VP16, induced GUS activity much more than the wild-type AhR in the transgenic tobacco plants. Plants carrying AhRV expressed the GUS reporter gene in a dose- and time-dependent manner when treated with MC; GUS activity was detected at 5 nM MC on solid medium and at 12 h after soaking in 25 μM MC. Histochemical GUS staining showed that this system was active mainly in leaf and stem. These results suggest that the AhR-mediated reporter gene expression system has potential for the bioassay of dioxins in the environment and as a novel gene expression system in plants. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Morphological characterization of follicle deviation in Nelore (Bos indicus) heifers and cows

Follicle diameter deviation is defined as the beginning of the differential change in growth rates between the largest and next largest follicles subsequent to wave emergence and is considered a key component of follicle selection. Follicle selection has been extensively studied in European breeds of cattle (Bos taurus) but has not been critically studied in Zebu breeds (Bos indicus). The objectives of the present study were to determine and compare the morphological characteristics of deviation associated with the first post-ovulatory wave (Wave 1) of the estrous cycle in Nelore heifers (n=8) and nonlactating cows (n=11). Beginning on the day of ovulation (day 0), the three largest follicles (F1-F3, respectively) were individually tracked every 12 h for 6d using transrectal ultrasonography. In individual animals, deviation was determined graphically using visual inspection of the diameter profiles of F1, F2 and sometimes F3 (observed deviation) and mathematically using segmented regression analysis of the diameter differences between F1 and F2 or sometimes F3 (calculated deviation). Mean day of emergence of Wave 1 when F1 reached >3 mm (approximately 1 d after ovulation) and growth rate of F1 during deviation (approximately 1.4 mm/d) were not significantly different between heifers and cows. The results of determining the beginning of deviation within heifers and cows using the observed and calculated methods were not significantly different. Averaged over both methods, diameter deviation occurred 2.8 d after ovulation when F1 reached 5.7 mm in heifers, and 2.4 d after ovulation when F1 reached 6.1 mm in cows. In conclusion, the emergence of Wave 1 and growth rates and diameters of the future dominant follicles at the beginning of deviation were similar in Nelore heifers and nonlactating cows, regardless of the methods used to determine deviation. Relative to Holstein cattle, emergence of Wave 1 appeared to occur about 1 d later and diameter of the future dominant follicle at the beginning of deviation was about 2 mm smaller in Nelore.     

Developmental changes of FSH-R, LH-R, ER-beta and GnRH-I expression in the ovary of prepubertal ducks (Anas platyrhynchos)

Normal ovarian development is dependent on stimulation of the gonadotropic hormones, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), as well as some regulatory factors locally produced in ovary, e.g. 17beta-estradiol (E2) and gonadotropin-releasing hormone (GnRH), mediated by their respective receptors. In order to elucidate the potential roles of LH, FSH, E2 and GnRH-I during early follicular development in prepubertal ducks, mRNA expression of LH-R, FSH-R, ER-β and GnRH-I in ovaries of 1-day-old (D1), 30-day-old (D30), 60-day-old (D60) and 90-day-old (D90) ducks was measured with semi-quantitative RT-PCR using β-actin as an internal standard. The ovary index (the ratio of ovary weight/body mass) did not change from D30 to D90, while the ovary weight and serum E2 levels rose progressively, indicating the prepubertal development of the ovary. Ovarian expression of FSH-R, LH-R, ER-β and GnRH-I mRNA changed greatly during this period. Abundance of FSH-R and ER-β mRNA went up gradually from D1 to D60, followed by a decline on D90. LH-R and GnRH-I mRNA expression increased from D1 to D90, reaching a peak at D90. These results indicate that the developing ovary is highly responsive to the regulation of FSH during the early stage, while close to the onset of sexual maturation, the ovary is likely more responsive to LH. In addition, the expression of GnRH-I and ER-β mRNA in the ovary suggest that GnRH-I and E2 are involved in the regulation of prepubertal follicular development in the ovary of ducks.     

Follicle populations and gene expression profiles of Nelore and Angus heifers with low and high ovarian follicle counts

The number of antral follicles counted (AFC) by ultrasound is associated with fertility in cattle. Cows with higher follicle count (HFC) have higher performance in reproductive‐assisted technologies than cows with lower follicle count (LFC). In this study, we aimed to define the preantral follicle count by histology and to identify differentially expressed genes (DEGs) using a microarray in Nelore and Angus heifers with HFC and LFC. The ovaries of each animal were scanned with an ultrasound device 12 to 24 hr after estrus. The groups were formed based on the average number of total follicles (≥3 mm) counted in each breed consistently ± the standard deviation. For the histological analysis, preantral follicles were counted and classified under a stereo microscope, and follicle density was determined. Microarray analysis was performed on pools of three follicles dissected from the ovaries of 15 Nelore (6 HFC and 9 LFC) and 17 Angus heifers (9 HFC and 8 LFC). Angus heifers have increased total and primordial follicle density. Nelore heifers have increased antral follicle count. Different patterns of gene expression regulate follicle recruitment and development in Angus and Nelore heifers and may be associated with the different follicle densities observed in Angus versus Nelore heifers. Furthermore, HFC heifers presented increased expression of genes associated with cellular development and metabolism.     

Expression and regulation of mRNAs for insulin-like growth factor-I receptor and LH receptor in corpora lutea

Relationship between insulin-like growth factor-I receptor (IGF-IR) and luteinizing hormone receptor (LHR) mRNA expression as well as their regulation was determined in rat corpora lutea (CL) . In the CL of estrous cycle rat, LHR mRNA positive CL expressed high level of mRNA of IGF-IR. While the expression of LHR mRNA decreased on estrus, the CL still expressed relatively high level of IGF-IR mRNA. In pseudopregnant rat CL, the expression level of LHR mRNA was low on day 1, the most intense signals were detected on day 8, the signals of LHR mRNA became undetectable on day 14. In contrast to LHR expression, the high level of IGF-IR mRNA was observed in pseudopregnant CL of day 1, and thereafter its signals were detected from day 2 to day 14. Pregnant rat CL expressed both LHR and IGF-IR mRNAs. IGF-I stimulated LHR expression in CL. PGF2 inhibited expression of IGF-IR and LHR. PGE2 negated the inhibiting effects of PGF2. These data suggest that IGF-I may be involved in regulating CL function, and maintaining CL structure through changes in expression of its receptors. Inhibited expression of IGF-IR by PGF2 may be part of mechanisms for regression of CL.     

Heart extracellular matrix gene expression profile in the vitamin D receptor knockout mice

1,25-Dihydroxyvitamin D₃ [1,25D] deficiency and vitamin D receptor [VDR] genotypes are risk factors for several diseases and disorders including heart diseases. Extracellular matrix (ECM) remodeling mediated by matrix metalloproteinases [MMPs] contributes to progressive left ventricular remodeling, dilation, and heart failure. In the present study, we used high-density oligonucleotide microarray to examine gene expression profile in wild type [WT] and vitamin D receptor knockout mice (VDR KO) which was further validated by RT-PCR. Microarray analysis revealed tissue inhibitors of metalloproteinases [TIMP-1 and TIMP-3] were significantly under expressed in VDR KO mice as compared to WT mice which was further validated by RT-PCR. Zymography and RT-PCR showed that MMP-2 and MMP-9 were up regulated in VDR KO mice. In addition, cross-sectional diameter and longitudinal width of the VDR KO heart myofibrils showed highly significant cellular hypertrophy. Trichrome staining showed marked increase in fibrotic lesions in the VDR KO mice. Heart weight to body weight ratio showed 41% increase in VDR KO mice when compared to WT mice. This data supports a role for 1,25D in heart ECM metabolism and suggests that MMPs and TIMPs expression may be modulated by vitamin D.     

Expression and regulation of mRNAs for insulin-like growth factor-I receptor and LH receptor in corpora lutea

Relationship between insulin-like growth factor-l receptor (IGF-IR) and luteinizing hormone receptor (LHR) mRNA expression as well as their regulation was determined in rat corpora lutea (CL) . In the CL of estrous cycle rat, LHR mRNA positive CL expressed high level of mRNA of IGF-IR. While the expression of LHR mRNA decreased on estrus, the CL still expressed relatively high level of IGF-IR mRNA. In pseudopregnant rat CL, the expression level of LHR mRNA was low on day 1, the most intense signals were detected on day 8, the signals of LHR mRNA became undetectable on day 14. In contrast to LHR expression, the high level of IGF-IR mRNA was observed in pseudopregnant CL of day 1, and thereafter its signals were detected from day 2 to day 14. Pregnant rat CL expressed both LHR and IGF-IR mRNAs. IGF-I stimulated LHR expression in CL. PGF2ainhibited expression of IGF-IR and LHR. PGE2 negated the inhibiting effects of PGF2α. These data suggest that IGF-I may be involved in regulating CL function, and maintai     

Separation of chitooligosaccharides and the potent effects on gene expression of cell surface receptor CR3

Chitooligosaccharides were prepared through hydrolysis of colloidal chitosan by enzyme source from Aspergillus fumigatus BSF114. Chitosan pentamer (COS5) and chitosan hexamer (COS6) were isolated and purified from COS by the ultra-filtration, nano-filtration, ethanol precipitation and the CM-Sephadex C-25 column. COS5 consisted of (GlcN)₄ (59.84%) and (GLcN)₅ (40.16%). COS6, however, mainly consisted of (GLcN)₆ (93.11%) and (GLcN)₅ (6.89%). Effects of COS5 and COS6 in vivo and in vitro on gene expression of cell surface CR3 receptor were investigated by relatively quantitative RT-PCR and ELISA. The results showed that the expression of CR3 mRNA could be promoted by both COS5 and COS6. The promotion effect caused by COS6 was greater than that of COS5.     

Comparison of gonadorelin products in lactating dairy cows: Efficacy based on induction of ovulation of an accessory follicle and circulating luteinizing hormone profiles

This study evaluated whether the four gonadorelin products that are commercially available in the United States produce comparable ovulation responses in lactating cows. Dairy cows at 7 d after last gonadotropin-releasing hormone (GnRH) treatment of Ovsynch (Day 7), with a corpus luteum (CL) ≥15 mm and at least one follicle ≥10 mm, were evaluated for response to GnRH treatment. Selected cows were randomized to receive (100 μg; im): (1) Cystorelin (n = 146); (2) Factrel (n = 132); (3) Fertagyl (n = 140); or (4) Ovacyst (n = 140). On Day 14, cows were examined for ovulation by detection of an accessory CL. Circulating luteinizing hormone (LH) concentrations were also evaluated in some cows after treatment with 100 μg (n = 10 per group) or 50 μg (n = 5 per group) GnRH. Statistical analyses were performed with the procedures MIXED and GLIMMIX of the SAS program. Percentage of cows ovulating differed (P < 0.01) among groups, with that for Factrel being lower (55.3%) than that for Cystorelin (76.7%), Fertagyl (73.6%), or Ovacyst (85.0%). There was no effect of batch, parity, or follicle size on ovulation response, but increasing body condition score decreased ovulation response. There was a much greater LH release in cows treated with 100 μg than in those treated with 50 μg, but there were no detectable differences among products in time to LH peak, peak LH concentration, or area under the LH curve and no treatment effects nor treatment by time interactions on circulating LH profile. Thus, ovulation response to Factrel on Day 7 of the cycle was lower than that for other commercial GnRH products, although a definitive mechanism for this difference between products was not demonstrated.     

Comparison of embryo yield and pregnancy rate between in vivo and in vitro methods in the same Nelore (Bos indicus) donor cows

To investigate why the preferred means to produce bovine embryos in Brazil has changed from in vivo to in vitro, we compared these two approaches in the same Nelore cows (n = 30) and assessed total embryo production and pregnancy rates. Without a specific schedule, all cows were subjected to ultrasound-guided ovum pick up (OPU)/in vitro production (IVP) and MOET, with intervals ranging from 15 to 45 d between procedures, respectively. To produce in vivo embryos, cows were superovulated and embryos were recovered nonsurgically from 1 to 3 times (1.4 ± 0.6), whereas OPU/IVP was repeated from 1 to 5 times (3.2 ± 1.2) in each donor cow during a 12-mo interval. Embryos obtained from both methods were transferred to crossbred heifers. On average, 25.6 ± 15.3 immature oocytes were collected per OPU attempt. The average number of embryos produced by OPU/IVP (9.4 ± 5.3) was higher (P < 0.05) than the MOET method (6.7 ± 3.7). However, pregnancy rates were lower (P < 0.05) following transfer of IVP (33.5%) versus in vivo-derived embryos (41.5%) embryos. Embryonic losses between Days 30 and 60 and fetal sex ratio were similar (P > 0.05) between in vivo and in vitro-derived embryos. We concluded that in Nelore cows, with an interval of 15 d between OPU procedures, it was possible to produce more embryos and pregnancies compared to conventional MOET.     

A comparative study of ryanodine receptor (RyR) gene expression levels in a basal ray-finned fish, bichir (Polypterus ornatipinnis) and the derived euteleost zebrafish (Danio rerio)

Ryanodine receptors (RyRs) are large homotetrameric protein complexes that mediate the release of intracellular stores of calcium. Mammals possess three gene copies, RyR1, RyR2, and RyR3 that are expressed in a variety of tissue types. Teleost fish express RyR1a and RyR1b genes that are expressed in slow twitch skeletal muscle and fast twitch skeletal muscles respectively. Here we report the results of a survey of the genome of bichir (Polypterus ornatipinnis), considered the most basal ray-finned fish, for its RyR genes. The bichir genome encodes four RyR genes, RyR1a, RyR1b, RyR2, and RyR3 that phylogenetically cluster with their vertebrate orthologs. Quantitative real time PCR shows fibre type-specific expression of the RyR1a and RyR1b genes. The RyR3 gene, however, is down regulated in bichir in contrast to derived teleosts including zebrafish in which the RyR1 and RyR3 genes are co-expressed at equivalent levels.     

Myometrial effects of selective estrogen receptor modulators on estradiol-responsive gene expression are gene and cell-specific

We examined in vivo effects of selective estrogen receptor modulators (SERMs) 4-OH-tamoxifen (Tam), GW 5638 (GW) and EM-800 (EM) on myometrial gene expression. The uteri of ovariectomized ewes were infused with 10⁻⁷ M of one SERM via indwelling catheters for 24 h preceding hysterectomy. Half of the ewes in each SERM group received an intramuscular injection of 50 μg 17β-estradiol (E2) 18 h prior to hysterectomy. Northern blot analysis and in situ hybridization demonstrated that E2 increased estrogen receptor (ER), progesterone receptor (PR) and cyclophilin (CYC) gene expression in the cells of both inner layer of myometrium (IM) and outer layer of myometrium (OM) as well as glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene expression in OM. Tam also increased ER mRNA levels in OM. EM appeared to increase ER gene expression, but antagonized E2’s up-regulation of PR and CYC gene expression in both IM and OM. Tam and GW also antagonized E2 up-regulation of PR gene expression in OM but not IM. No SERM affected GAPDH gene expression with or without E2. Immunohistochemistry indicated that E2 increased nuclear ER and PR protein levels in both IM and OM. EM was unique in up-regulating ER protein levels, opposite to its effects in endometrial cells. All SERMs tested antagonized this increase in PR immunostaining preferentially in OM compared to the IM layer. These results illustrate gene and cell layer-specific effects of SERMs in sheep myometrium.     

Analysis of serotonin receptor 2A gene (HTR2A): Association study with autism spectrum disorder in the Indian population and investigation of the gene expression in peripheral blood leukocytes

Several studies suggest involvement of serotoninergic system in the pathophysiology of Autism Spectrum Disorder (ASD). The 5-HT receptor binding studies using ³H-lysergic acid diethylamide (³H-LSD) and linkage analysis provided evidences to consider HTR2A as a potential candidate gene for ASD. The three SNPs, −1438A/G (rs6311), 102T/C (rs6313) and 1354C/T (rs6314) of HTR2A have been well studied in the etiology of various neuropsychiatric disorders. But studies on association of this gene with ASD are limited to two reports from American and Korean populations. Additionally there are reports, which demonstrated paternal imprinting of HTR2A with expression from only one allele. So far no reports are available on HTR2A and its association with any neuropsychiatric disorders from Indian population. Therefore, the present study investigates association of the above mentioned three markers of HTR2A with ASD in Indian population using population and family-based approaches. The study also deals with allelic expression pattern of HTR2A in Peripheral Blood Leukocytes (PBLs) to understand the parental imprinting status. The genotyping analyses were carried out for probands, parents and controls. The subsequent association analyses did not show association of these markers with ASD. So, HTR2A is unlikely to be a genetic marker for ASD in Indian population. The expression analyses showed absence of monoallelic expression, suggesting lack of parental imprinting of HTR2A gene. However, we noticed methylation of the CpG sites at −1438A/G and 102T/C loci of HTR2A gene. Further bioinformatics analysis revealed absence of CpG islands in the promoter of the gene supporting biallelic expression pattern of HTR2A in PBLs.     

Ovulation rate, embryo mortality and intrauterine growth retardation in obese swine with gene polymorphisms for leptin and melanocortin receptors

The Mediterranean Iberian pigs are obese genotypes, due to a leptin resistance syndrome related to leptin receptor gene polymorphisms. The Iberian pig is affected by a lower prolificacy when compared to lean breeds, and thus may constitute a good animal model for adverse effects of obesity in reproductive performance. The present study determined possible differences in rates of ovulation and embryo implantation and later incidence of embryo mortality and intrauterine growth retardation (IUGR) in sows of Iberian breed (n = 23) and highly-prolific lean commercial crosses (Large White × Landrace, n = 17) at two critical periods of swine pregnancy: Day 21 (just after achievement of trophoblast attachment) and Day 35 (just after completion of the transition from late embryo to early foetal stage). Two different reproductive performances were identified in the Iberian breed; 58.3% of the females had lower ovulation rates than LWxL (13.2 ± 2.3 vs 22.5 ± 1.6, P < 0.05), but 41.7% had a similar number of ovulations (18.2 ± 3.9). However, those Iberian sows having high ovulatory rates showed a high incidence of regression of corpora lutea and embryo losses between Days 21 and 35, which was not found in Iberian females with low ovulation rates; therefore, the number of viable embryos was similar in both Iberian groups (8.2 ± 1.0 and 8.4 ± 1.0) and lower that in highly-prolific LWxL (14.8 ± 1.8, P < 0.05). At Day 35, a total of 167 conceptuses (73 LWxL and 94 IB) were evaluated for IUGR. The LWxL conceptuses were longer and wider than Iberian (69.5 ± 0.1 and 64.4 ± 0.1 vs 49.9 ± 0.1 and 41.9 ± 0.1 mm, P < 0.0001). However, Iberian conceptuses were heavier than LWxL (107.4 ± 6.6 vs 68.6 ± 2.4 g) due to a lower quantity of fluids and a higher development of the placental tissues in comparison to the embryo itself. In conclusion, current study indicates a bimodal effect of obese genotypes on reproductive performances, either by lowering ovulation rate or by increased embryo losses in the first third of pregnancy.