Constitutive and follicle-stimulating hormone-induced action of somatostatin receptor-2 on regulation of apoptosis and steroidogenesis in bovine granulosa cells

[68 Ga]-DOTATATE PET/MR-based evaluation of physiologic somatostatin receptor 2 expression in the adult pituitary gland as a function of age and sex in a prospective cohort

PURPOSE

The pituitary gland has the fourth highest physiologic avidity of [68 Ga]-DOTATATE. In order to guide our understanding of [68 Ga]-DOTATATE PET in clinical contexts, accurate characterization of the normal pituitary gland is first required. This study aimed to characterize the normal pituitary gland using dedicated brain [68 Ga]-DOTATATE PET/MRI as a function of age and sex.

METHODS

A total of 95 patients with a normal pituitary gland underwent brain [68 Ga]-DOTATATE PET examinations for the purpose of diagnosing CNS SSTR2 positive tumors (mean age: 58.9, 73% female). Maximum SUV of the pituitary gland was obtained in each patient. SUV of superior sagittal sinus was obtained to calculate normalized SUV score (SUVR) of the gland. The anatomic size of the gland was collected as maximum sagittal height (MSH). Correlations with age and sex were analyzed.

RESULTS

The mean SUV and SUVR of the pituitary gland were 17.6 (range: 7-59.5, SD = 7.1) and 13.8 (range: 3.3-52.6, SD = 7.2), respectively. Older females had significantly higher SUV of the pituitary gland compared to younger females. When stratified by age and sex, both older and younger females had significantly higher pituitary SUV than older males. SUVR did not differ significantly by age or sex. MSH of the pituitary gland in younger females was significantly greater than in younger males at all age cutoffs.

CONCLUSION

This study provides an empiric profiling of the physiological [68 Ga]-DOTATATE avidity of the pituitary gland. The findings suggest that SUV may vary by age and sex and can help guide the use of [68 Ga]-DOTATATE PET/MRI in clinical and research settings. Future studies can build on these findings to investigate further the relationship between pituitary biology and demographic factors.

Evaluation of a Novel DNA Vaccine Double Encoding Somatostatin and Cortistatin for Promoting the Growth of Mice

Animal growth traits are directly linked with the economics of livestock species. A somatostatin DNA vaccine has been developed to improve the growth of animals. However, the growth-promoting effect is still unsatisfying. The current study aimed to evaluate the effect of a novel eukaryotic dual expression vaccine known as pIRES-S/CST14-S/2SS, which encodes the genes obtained by fusing somatostatin (SS) and cortistatin (CST) into hepatitis B surface antigen (HBsAg). After transfection into GH3 cells with pIRES-S/CST14-S/2SS, green fluorescence signals were observed by fluorescence microscopy, suggesting the effective expression of CST and SS in GH3 cells using the IRES elements. Subsequently, both GH and PRL levels were found to be significantly lower in pIRES-S/CST14-S/2SS-treated cells as compared to the control group (p < 0.05). Furthermore, the antibody level, hormone secretion, and weight gain in the mice injected with novel recombinant plasmids were also evaluated. The anti-SS antibodies were detectable in all vaccine treated groups, resulting in significantly higher levels of GH secretion (p < 0.05). It is worth mentioning that pIRES-S/CST14-S/2SS (10 μg/100 μL) vaccinated mice exhibited a higher body weight gain in the second immunization period. This study increases the understanding of the relationship between somatostatin and cortistatin, and may help to develop an effective growth-promoting DNA vaccine in animals.

Knockdown of CYP19A1 in Buffalo Follicular Granulosa Cells Results in Increased Progesterone Secretion and Promotes Cell Proliferation

Cytochrome P450 aromatase 19A1 (CYP19A1) is a critical enzyme in estrogen synthesis. However, the effect of CYP19A1 on cell growth and hormone secretion of buffalo follicular granulosa cells (BFGCs) is poorly understood. The objective of this study was to assess the role of CYP19A1 in cell proliferation and hormone secretion of BFGCs by knocking down CYP19A1 mRNA expression. The mRNA expression level of CYP19A1 gene was knocked down in BFGCs using the siCYP19A1-296 fragment with the best interference efficiency of 72.63%, as affirmed by real-time quantitative PCR (qPCR) and cell morphology analysis. The CYP19A1 knockdown promoted the proliferation of BFGCs through upregulating the mRNA expression levels of six proliferation-related genes (CCND1, CCNE1, CCNB1, CDK2, CDKN1A, and CDKN1B). Moreover, CYP19A1 knockdown increased (P < 0.05) the concentrations of progesterone secretion (P4) in BFGCs through increasing the mRNA expression levels of three steroidogenic genes (HSD17B1, HSD17B7, and CYP17A1). Our data further found that the FSH could inhibit the mRNA expression level of CYP19A1 in BFGCs, while LH obtains the opposite effect. These findings showed that the CYP19A1 knockdown had a regulatory role in the hormone secretion and cell proliferation in BFGCs.

Phospholipase C inhibits apoptosis of porcine primary granulosa cells cultured in vitro

Phospholipase C (PLC) can participate in cell proliferation, differentiation and aging. However, whether it has a function in apoptosis in porcine primary granulosa cells is largely uncertain. The objective of this study was to examine the effects of PLC on apoptosis of porcine primary granulosa cells cultured in vitro. The mRNA expression of BAK, BAX and CASP3, were upregulated in the cells treated with U73122 (the PLC inhibitor). The abundance of BCL2 mRNA, was upregulated, while BAX and CASP3 mRNA expression was decreased after treatment with m-3M3FBS (the PLC activator). Both the early and late apoptosis rate were maximized with 0.5 μM U73122 for 4 h. The rate of early apoptosis was the highest at 4 h and the rate of late apoptosis was the highest at 12 h in the m-3M3FBS group. The protein abundance of PLCβ1, protein kinase C β (PKCβ), calmodulin-dependent protein kinaseII α (CAMKIIα) and calcineurinA (CalnA) were decreased by U73122, and CAMKIIα protein abundance was increased by m-3M3FBS. The mRNA expression of several downstream genes (CDC42, NFATc1, and NFκB) was upregulated by PLC. Our results demonstrated that apoptosis can be inhibited by altering PLC signaling in porcine primary granulosa cells cultured in vitro, and several calcium^-sensitive targets and several downstream genes might take part in the processes.

Effect of melatonin on regulation of apoptosis and steroidogenesis in cultured buffalo granulosa cells

This study was aimed to address melatonin receptor expression, mRNA level of hypothalamus and hypophysis hormone receptors (GnRHR, FSHR, and LHR), steroidogenesis, cell cycle, apoptosis, and their regulatory factors after addition of melatonin for 24 hr in cultured buffalo granulosa cells (GCs). The results revealed that direct addition of different concentrations of melatonin (100 pM, 1 nM, and 100 nM) resulted in significant upregulation (p < 0.05) of mRNA level of melatonin receptor 1a (MT1) without affecting melatonin receptor 1b (MT2). Melatonin treatment significantly downregulated (p < 0.05) mRNA level of FSH and GnRH receptors, whereas 100 nM dose of melatonin significantly increased mRNA level of LH receptor. Treatment with 100 nM of melatonin significantly decreased the basal progesterone production with significant decrease (p < 0.05) in mRNA levels of StAR and p450ssc, and lower mRNA level of genes (Insig1, Lipe, and Scrab1) that affect cholesterol availability. Melatonin supplementation suppressed apoptosis (100 nM, p < 0.05) and enhanced G2/M phase (1 nM, 100 nM, p < 0.05) of cell cycle progression which was further corroborated by decrease in protein expression of caspase-3, p21, and p27 and increase in bcl2. Our results demonstrate that melatonin regulates gonadotrophin receptors and ovarian steroidogenesis through MT1. Furthermore, the notion of its incorporation in apoptosis and proliferation of buffalo GCs extends its role in buffalo ovaries.

Treatment of female rhesus macaques with a somatostatin receptor antagonist that increases oocyte fertilization rates without affecting post-fertilization development outcomes

PURPOSE

To determine the effects of PGL1001, a somatostatin receptor isoform-2 (SSTR-2) antagonist, on ovarian follicle development, oocyte fertilization, and subsequent embryo developmental potential in the rhesus macaque.

METHODS

Cycling female rhesus macaques (N = 8) received vehicle through one menstrual (control) cycle, followed by daily injections of PGL1001, a SSTR-2 antagonist, for three menstrual (treatment) cycles. Main endpoints include overall animal health and ovarian hormones (e.g., estradiol [E2], progesterone [P4], and anti-Müllerian hormone [AMH]), ovarian circumference, numbers of oocytes and their maturation status following controlled ovarian stimulation (COS), as well as oocyte fertilization and subsequent blastocyst rates that were assessed in control and PGL1001 treatment cycles. Circulating PGL1001 levels were assessed at baseline as well as 6, 60, and 90 days during treatment.

RESULTS

PGL1001 treatment did not impact overall animal health, menstrual cycle length, or circulating levels of ovarian hormones (E2, P4, and AMH) in comparison to vehicle treatment during natural cycles. PGL1001 treatment increased (p ˂ 0.05) ovarian circumference and the day 8 to day 1 ratio of AMH levels (p ˂ 0.05) during a COS protocol, as well as oocyte fertilization rates compared to the vehicle treatment interval. Blastocyst development rates were not significantly different between vehicle and PGL1001 treatment groups.

CONCLUSION

Prolonged treatment with PGL1001 appears to be safe and does not affect rhesus macaque general health, menstrual cycle length, or ovarian hormone production. Interestingly, PGL1001 treatment increased the fertilization rate of rhesus macaque oocytes collected following ovarian stimulation.

Novel insights into the genetic basis of buffalo reproductive performance

Background

Fertility is a complex trait that has a major impact on the development of the buffalo industry. Genome-wide association study (GWAS) has increased the ability to detect genes influencing complex traits, and many important genes related to reproductive traits have been identified in ruminants. However, reproductive traits are influenced by many factors. The development of the follicle is one of the most important internal processes affecting fertility. Genes found by GWAS to be associated with follicular development may directly affect fertility. The present study combined GWAS and RNA-seq of follicular granulosa cells to identify important genes which may affect fertility in the buffalo.

Results

The 90 K Affymetrix Axiom Buffalo SNP Array was used to identify the SNPs, genomic regions, and genes that were associated with reproductive traits. A total of 40 suggestive loci (related to 28 genes) were identified to be associated with six reproductive traits (first, second and third calving age, calving interval, the number of services per conception and open days). Interestingly, the mRNA expressions of 25 of these genes were also observed in buffalo follicular granulosa cells. The IGFBP7 gene showed high level of expression during whole antral follicle growth. The knockdown of IGFBP7 in buffalo granulosa cells promoted cell apoptosis and hindered cell proliferation, and increased the production of progesterone and estradiol. Furthermore, a notable signal was detected at 2.3–2.7 Mb on the equivalent of bovine chromosome 5 associated with age at second calving, calving interval, and open days.

Conclusions

The genes associated with buffalo reproductive traits in this study may have effect on fertility by regulating of follicular growth. These results may have important implications for improving buffalo breeding programs through application of genomic information.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5208-6) contains supplementary material, which is available to authorized users.

Structural and functional analysis of two novel somatostatin receptors identified from topmouth culter (Erythroculter ilishaeformis)

In the present study, we cloned and characterized two somatostatin (SS) receptors (SSTRs) from topmouth culter (Erythroculter ilishaeformis) designated as EISSTR6 and EISSTR7. Analysis of EISSTR6 and EISSTR7 signature motifs, 3D structures, and homology with the known members of the SSTR family indicated that the novel receptors had high similarity to the SSTRs of other vertebrates. EISSTR6 and EISSTR7 mRNA expression was detected in 17 topmouth culter tissues, and the highest level was observed in the pituitary. Luciferase reporter assay revealed that SS14 significantly inhibited forskolin-stimulated pCRE-luc promoter activity in HEK293 cells transiently expressing EISSTR6 and EISSTR7, indicating that the receptors can be activated by SS14. We also identified phosphorylation sites important for the functional activity of EISSTR6 and EISSTR7 by mutating Ser^{23, 43, 107, 196, 311} and Ser^{7, 29, 61, 222, 225} residues, respectively, to Ala, which significantly reduced the inhibitory effects of SS14 on the CRE promoter mediated by EISSTR6 and EISSTR7. Furthermore, treatment of juvenile topmouth culters with microcystin-LR or 17β-estradiol significantly affected EISSTR6 and EISSTR7 transcription in the brain, liver and spleen, suggesting that these receptors may be involved in the pathogenic mechanisms induced by endocrine disruptors. Our findings should contribute to the understanding of the structure-function relationship and evolution of the SSTR family.

Knockdown of CREB1 promotes apoptosis and decreases estradiol synthesis in mouse granulosa cells

Cyclic AMP response element-binding protein 1 (CREB1), a member of the CREB family, is known to be involved in follicular growth, ovulation, and ovarian disease. However, the physiological function of CREB1 in mouse granulosa cells (mGCs) remains lagerly unknown. The aim of this study was to determine the role of CREB1 in mGCs by knocking down CREB1 expression. CREB1 knock-down in mGCs at the mRNA and protein levels, was confirmed by quantitative real-time polymerase chain reaction and western blot. Results of enzyme linked immunosorbent assay revealed that CREB1 knockdown significantly decreased the concentrations of estradiol (E2) and progesterone (P4) in mGCs. Furthermore, the CREB1 knockdown in mGCs promoted cell proliferation and apoptosis, and arrested the cell cycle in S-phase. To elucidate the regulatory mechanism underlying the effects of CREB1 knockdown on steroid synthesis, cell cycle, and apoptosis, we measured the protein expression levels of several related genes in mGCs knocked down CREB1. When CREB1 was knocked down, the expression of Cyp1b1 and Cyp19a1, which encode steroidogenic enzymes, was down-regulated; the expression of the cell cycle factors CyclinA1, CyclinB1, and CyclinD2 were significantly decreased. Among apoptosis-related genes, Bcl-2 was down-regulated, whereas Bax and cleaved Caspase3 were upregulated. Moreover, CREB1 knockdown significantly decreased expression level of Has2, Ptgs2, and Igfbp4, which are essential genes for folliculogenesis in mGCs. Taken together, these findings suggested that CREB1 might be a key regulator of mGCs through regulating steroid synthesis, cell proliferation, cell cycle, apoptosis, and other regulators of folliculogenesis.

Regulatory roles of ephrinA5 and its novel signaling pathway in mouse primary granulosa cell apoptosis and proliferation

Recent findings suggest that ephrinA5 (Efna5) has a novel role in female mouse fertility, in addition to its well-defined role as a neurogenesis factor. Nevertheless, its physiological roles in ovarian granulosa cells (GC) have not been determined. In this study, mouse GC were cultured and transfected with ephrin A5 siRNA and negative control to determine the effects of Efna5 on GC apoptosis, proliferation, cell cycle progression, and related signaling pathways. To understand the mode signaling, the mRNA expression levels of Efna5 receptors (Eph receptor A5, Eph receptor A3, Eph receptor A8, and Eph receptor B2) were examined. Both mRNA and protein expressions of apoptosis-related factors (Bax, Bcl-2, Caspase 8, Caspase 3, and Tnfα) and a proliferation marker, Pcna, were investigated. Additionally, the role of Efna5 on paracrine oocyte-secreted factors and steroidogenesis hormones were also explored. Efna5 silencing suppressed GC apoptosis by downregulating Bax and upregulating Bcl-2 in a Caspase 8-dependent manner. Efna5 knockdown promoted GC proliferation via p-Akt and p-ERK pathway activation. The inhibition of Efna5 enhanced BMH15 and estradiol expression, but suppressed GDF9, while progesterone level remained unaltered. These results demonstrated that Efna5 is a pro-apoptotic agent in GC and plays important role in folliculogenesis by mediating apoptosis, proliferation, and steroidogenesis in female mouse. Therefore Efna5 might be potential therapeutic target for female fertility disorders.

SSTR2 associated with neuronal apoptosis after intracerebral hemorrhage in adult rats

Objective SSTR2 is a member of superfamily of SST receptor (SSTR), and widely expressed in the brain; however, the knowledge of its functions in area adjacent to hematoma after intracerebral hemorrhage (ICH) is still limited. Method The role of SSTR2 in the processes of ICH was explored by conducting an ICH rat model. Western blot and immunohistochemistry were employed to examine the level of SSTR2 in area adjacent to hematoma after ICH. Immunofluorescent staining was used to observe the spatial correlation of SSTR2 with cellular types adjacent to hematoma after ICH. RNA interference specific to SSTR2 was adopted in PC12 cells to clarify the causal correlation between SSTR2 and neuronal activities. Results Increased expression of SSTR2 was observed and restricted to the neurons adjacent to hematoma following ICH. Immunofluorescent staining showed that SSTR2 was significant increased in neurons, but not astrocytes or microglia. Increasing SSTR2 level was found to be accompanied by the up-regulation of activated caspase-3 and the down-expression of p-Akt in a time-dependent manner. What's more, using SSTR2 RNA interference (SSTR2-RNAi) in PC12 cells, we indicated that SSTR2 might have a pro-apoptotic role in neurons. Conclusion We speculated that SSTR2 might exert its pro-apoptotic function in neurons through inhibiting Akt activity following ICH.

Knockdown of CREB3/Luman by shRNA in Mouse Granulosa Cells Results in Decreased Estradiol and Progesterone Synthesis and Promotes Cell Proliferation

Luman (also known as LZIP or CREB3) is a transcription factor and a member of the cAMP responsive element-binding (CREB) family proteins. Although Luman has been detected in apoptotic granulosa cells and disorganized atretic bodies, the physiological function of Luman in follicular development has not been reported. Our objective is to determine the role of Luman in folliculogenesis by knocking down Luman expression in mouse GCs (granulosa cells) using shRNA. Luman expression was successfully knocked down in mouse GCs at the mRNA and protein level, as confirmed by real-time quantitative PCR, western blot and immunofluorescence staining, respectively. Knockdown of Luman significantly decreased the concentrations of estradiol (E2) and progesterone (P4) in cell culture medium. Furthermore, Luman knockdown promoted cell proliferation but had no effect on cell apoptosis. To elucidate the regulatory mechanism underlying the effects of Luman knockdown on steroid synthesis and cell cycle, we measured the mRNA and protein expression levels of several related genes. The expression of Star, Cyp19a1, and Cyp1b1, which encode steroidogenic enzymes, was down-regulated, while that of Cyp11a1 and Runx2, which also encode steroidogenic enzymes, was up-regulated. The expression of the cell cycle factors Cyclin A1, Cyclin B1, Cyclin D2, and Cyclin E was significantly up-regulated. Among apoptosis-related genes, only Bcl-2 was down-regulated, while Caspase 3, Bax and p53 were not significantly affected, suggesting that Luman knockdown may regulate cell cycle activity and hormone secretion at the transcriptional and translational level in mouse GCs. The expression of two important genes associated with folliculogenesis in mouse GCs, Has2 and Ptgs2, were also significantly altered by Luman knockdown. In conclusion, the findings of this study indicate that Luman regulates mouse GCs modulation of steroid synthesis, cell cycle activity and other regulators of folliculogenesis.

Herp depletion arrests the S phase of the cell cycle and increases estradiol synthesis in mouse granulosa cells

The endoplasmic reticulum (ER) stress response has been implicated in the development, atresia and luteinization of ovarian follicles. However, there have been few reports concerning the role of Herp, an ER stress-induced protein, in follicular development. The present study aims to detect the distribution and cyclic variations of Herp during the estrous cycle and to reveal the roles of Herp in regulating the cell cycle, apoptosis and steroid hormone biosynthesis in mouse granulosa cells. In this study, immunohistochemistry staining showed that Herp expression was primarily in the granulosa cells and oocytes. Furthermore, we constructed recombinant lentiviral vectors for Herp short hairpin interfering RNA (shRNA) expression; immunofluorescence staining, real-time quantitative PCR (RT-qPCR) and western blot analysis revealed that Herp was successfully knocked down. Flow cytometry showed that knockdown of Herp arrested granulosa cells at the S phase of the cell cycle. More importantly, ELISA analysis revealed that Herp knockdown significantly upregulated the concentration of estradiol (E2) in the culture supernatants. RT-qPCR was performed to determine the regulatory mechanism of Herp knockdown in the cell cycle, and in steroid synthesis, RT-qPCR analysis revealed that Herp knockdown upregulated the mRNA expression of steroidogenic enzymes (Cyp19a1) and downregulated metabolic enzymes (Cyp1b1) and cell cycle factors (cyclin A1, cyclin B1 and cyclin D2). These results suggest that Herp may regulate the cell cycle and hormone secretions in mouse granulosa cells. The present study helps to elucidate the physiological functions of Herp as they relate to reproduction.

MAPK3/1 is conducive to luteinizing hormone-mediated C-type natriuretic peptide decrease in bovine granulosa cells

C-type natriuretic peptide (CNP) plays a role as an oocyte maturation inhibitor (OMI) in many species, including the bovine. However, the effects of luteinizing hormone (LH) on CNP expression and its potential mechanisms have not reported in the bovine. In the present study, we aimed to study the effects of LH on CNP expression and to illuminate the potential molecular mechanism in this process. Our results showed that LH induced epidermal growth factor receptor (EGFR) phosphorylation, mitogen-activated protein kinase3/1 (MAPK3/1) activation and CNP mRNA decrease in cultured bovine granulosa cells. Further study revealed that LH suppressed CNP expression via the MAPK3/1 signaling pathway, which was activated by the EGFR pathway. In conclusion, our research suggested that MAPK3/1 is involved in LH-mediated decrease of CNP and that this process is related to the EGFR and MAPK3/1 signal pathways.

Robo1/2 regulate follicle atresia through manipulating granulosa cell apoptosis in mice

Secreted Slit proteins and their Roundabout (Robo) receptors act as a repulsive cue to prevent axons from migrating to inappropriate locations during the development of the nervous system. Slit/Robo has also been implicated in reproductive system development, but the molecular mechanism of the Slit/Robo pathway in the reproductive system remains poorly understood. Using a transgenic mouse model, we investigated the function of the Slit/Robo pathway on ovarian follicle development and atresia. We first demonstrated that more offspring were born to mice with a partial knockout of the Robo1/2 genes in mice. We next showed that Robo1 and Robo2 are strongly expressed in ovarian granulosa cells. Apoptosis in granulosa cells was reduced when Robo1/2 were partially knocked out, and this observation was further verified by in vitro Robo1/2 knockout experiments in mouse and human granulosa cells. We also found that ovarian angiogenesis was enhanced by a partial lack of Robo1/2 genes. In summary, our data suggest that the Slit/Robo pathway can impact follicle development and atresia by influencing granulosa cell apoptosis.

Disruption of follistatin by RNAi increases apoptosis, arrests S-phase of cell cycle and decreases estradiol production in bovine granulosa cells

Follistatin (FST), a local regulator of gonadal functions is a powerful inhibitor of follicle stimulating hormone (FSH) secretion. In the present study, the expression of FST was partially silenced at both transcriptional and translational levels by RNAi-Ready pSIREN-RetroQ-ZsGreen Vector mediated recombinant pshRNA vectors in bovine granulosa cells (bGCs). The results showed that transfection with FST-1 and FST-2 vectors significantly down-regulated mRNA and protein expressions of follistatin by 51% (P = 0.0093) and 72% (P = 0.0078) respectively. After down-regulation of FST in bGCs, cell cycle was arrested at S-phase (9.2 ± 0.6 vs 12.5 ± 0.2, P = 0.0055), and apoptosis was significantly (21.3 ± 2.7 vs 13.9 ± 2.5, P = 0.0051) increased. These findings were further verified by down-regulation of protein level of B-cell leukemia/lymphoma 2 (Bcl2, P = 0.0423), and up-regulation of caspase-3 (P = 0.0362), p21 (P = 0.0067) and mRNA levels of Bcl2-associated X protein (Bax, P = 0.041). Knockdown of FST in bGCs significantly increased activin A concentration in culture medium, while level of estradiol (E2) was suppressed without affecting progesterone production. In addition, mRNA levels of all activin receptor subtypes [activin receptor types I (ACRI) and II (ACRIIA and ACRIIB)] and inhibin α-subunit were augmented (P < 0.05) without altering both inhibin β-subunits. These findings suggest that follistatin may participate in caspase3-dependent apoptosis through Bcl2/Bax gene family in bovine GCs, whereas, activin and its receptors are associated with its regulation. Activin-induced up-regulation of inhibin-α subunit in bGCs seems to be involved in the regulation of steroidogenesis.

Progesterone receptor expression in granulosa cells is suppressed by microRNA-378-3p

In developing ovarian follicles, the progesterone receptor (PGR) is essential for mediating transcription of key factors that coordinate cellular functions including follicular remodeling. With recent investigations examining the role of microRNA (miRNA) in regulating ovarian function we used a lentiviral approach to over express miR-378 in cultured primary porcine granulosa cells to study the role this miRNA may play in granulosa cell development. We revealed that miR-378-3p decreased protein levels and mRNA levels of PGR via targeting its 3'UTR. We observed that this regulation of PGR by miR-378-3p resulted in a corresponding decrease in gene transcripts of ADAMTS1, CTSL1, and PPARG, all known to be regulated by PGR and important for follicular maturation and remodeling. Our study provides the first evidence for post-transcriptional regulation of PGR and further elucidates the role of miR-378-3p in the ovary.

Knockdown of CEBPβ by RNAi in porcine granulosa cells resulted in S phase cell cycle arrest and decreased progesterone and estradiol synthesis

Cultured ovarian granulosa cells (GCs) are essential models to study molecular mechanisms of gene regulation during folliculogenesis. CCAAT enhancer binding proteins β (CEBPβ) has been identified in the ovary and is critical for follicular growth, ovulation and luteinization in mice. In the present study, hormonal treatment indicated that luteinizing hormone (LH) and exogenous human chorionic gonadotropins (hCG) significantly increased the expression of CEBPβ in porcine GCs. By RNAi-Ready pSIREN-RetroQ-ZsGreen Vector mediated recombinant pshRNA vectors, CEBPβ gene was successfully knocked down in porcine GCs, confirmed by mRNA and protein level analyzed by real time PCR and western blot, respectively. We further found that knockdown of CEBPβ significantly increased the expression of p-ERK1/2. Furthermore, CEBPβ knockdown arrested the GCs at S phase of cell cycle, but had no effects on cell apoptosis. More importantly, it markedly down regulated the concentration of estradiol (E2) and progesterone (P4) in the culture medium. To uncover the regulatory mechanism of CEBPβ knockdown on cell cycle and steroids synthesis, we found that the mRNA expression of bcl-2 (anti-apoptosis), StAR and Runx2 (steroid hormone synthesis) was up-regulated, while genes related to apoptosis (Caspase-3 and p53), hormonal synthesis (CYP11A1) and cell cycle (cyclinA1, cyclinB1, cyclinD1) were down-regulated, suggesting that knockdown of CEBPβ may inhibit apoptosis, regulate cell cycle and hormone secretions at the transcriptional level in porcine GCs. Furthermore, knockdown of CEBPβ significantly increased the expression of PTGS2 and decreased the expression of IGFBP4, Has2 and PTGFR which are important for folliculogenesis in porcine GCs. In conclusion, this study reveals that CEBPβ is a key regulator of porcine GCs through modulation of cell cycle, apoptosis, steroid synthesis, and other regulators of folliculogenesis.