BMP-4 suppresses progesterone production by inhibiting histone H3 acetylation of StAR in bovine granulosa cells in vitro

Possible roles of bone morphogenetic protein 4 in regulating endometrial function in cows

This study investigated the expression dynamics of bone morphogenetic protein 4 (BMP4) and its receptors (BMPR1A, BMPR1B, and BMPR2) in bovine endometrium and examined the physiological function and regulatory mechanism of BMP4 expression. The messenger RNA (mRNA) expression of BMP4 and its receptors was detected in bovine endometrium of both ipsilateral (corpus luteum [CL]-side) and contralateral (non-CL-side) uterine horns during the estrous cycle and early pregnancy. BMP4 protein levels were higher in the endometrial tissues obtained from those cows in early pregnancy than in the estrous cycle. Immunohistochemical analysis showed that BMP4 and its receptors were localized in endometrial epithelial cells. The addition of BMP4 to cultured endometrial epithelial cells did not affect caspase-3/-8 mRNA expression, whereas it significantly inhibited cell proliferation. Both prostaglandin (PG) E2 and PGF2α concentrations in the culture supernatant were decreased when stimulated by BMP4. Furthermore, BMP4 mRNA expression was increased by stimulation with tumor necrosis factor-α (TNF) and interferon-γ (IFNG). In conclusion, BMP4 is produced in bovine endometrial epithelial cells and may contribute to the regulation of cell proliferation and suppression of PG secretion through autocrine or paracrine mechanisms. BMP4 expression in the bovine endometrium may be regulated by TNF and IFNG.

BMP6 Promotes the Secretion of 17 Beta-Estradiol and Progesterone in Goat Ovarian Granulosa Cells

The purpose of this study was to investigate the effects of BMP6 on the function of goat ovarian granulosa cells (GCs). The results showed that the exogenous addition of BMP6 did not affect the EdU-positive ratio of ovarian GCs and had no significant effect on the mRNA and protein expression levels of the proliferation-related gene PCNA (p > 0.05). Meanwhile, BMP6 had no significant effect on the cycle phase distribution of GCs but increased the mRNA expression of CDK4 (p < 0.05) and CCND1 (p < 0.01) and decreased the mRNA expression of CCNE1 (p < 0.01). Moreover, BMP6 had no significant effect on the apoptosis rate of GCs and did not affect the mRNA expression levels of apoptosis-related genes BAX, BCL2, and Caspase3 (p > 0.05). Importantly, BMP6 upregulated the secretion of 17 beta-estradiol (E2) and progesterone (P4) in ovarian GCs (p < 0.01). Further studies found that BMP6 inhibited the mRNA expression of 3β-HSD and steroid synthesis acute regulator (StAR) but significantly promoted the mRNA expression of the E2 synthesis rate-limiting enzyme CYP19A1 and the P4 synthesis rate-limiting enzyme CYP11A1 (p < 0.01). Taken together, these results showed that the exogenous addition of BMP6 did not affect the proliferation, cell cycle, and apoptosis of goat ovarian GCs but promoted the secretion of E2 and progesterone P4 in ovarian GCs by upregulating the mRNA expressions of CYP19A1 and CYP11A1.

Cholesterol supports bovine granulosa cell inflammatory responses to lipopolysaccharide

During bacterial infections of the bovine uterus or mammary gland, ovarian granulosa cells mount inflammatory responses to lipopolysaccharide (LPS). In vitro, LPS stimulates granulosa cell secretion of the cytokines IL-1α and IL-1β, and the chemokine IL-8. These LPS-stimulated inflammatory responses depend on culturing granulosa cells with serum, but the mechanism is unclear. Here we tested the hypothesis that cholesterol supports inflammatory responses to LPS in bovine granulosa cells. We used granulosa cells isolated from 4-8 mm and > 8.5 mm diameter ovarian follicles and manipulated the availability of cholesterol. We found that serum or follicular fluid containing cholesterol increased LPS-stimulated secretion of IL-1α and IL-1β from granulosa cells. Conversely, depleting cholesterol using methyl-β-cyclodextrin diminished LPS-stimulated secretion of IL-1α, IL-1β and IL-8 from granulosa cells cultured in serum. Follicular fluid contained more high-density lipoprotein cholesterol than low-density lipoprotein cholesterol, and granulosa cells expressed the receptor for high-density lipoprotein, scavenger receptor class B member 1 (SCARB1). Furthermore, culturing granulosa cells with high-density lipoprotein cholesterol, but not low-density lipoprotein or very low-density lipoprotein cholesterol, increased LPS-stimulated inflammation in granulosa cells. Cholesterol biosynthesis also played a role in granulosa cell inflammation because RNA interference of mevalonate pathway enzymes inhibited LPS-stimulated inflammation. Finally, treatment with follicle-stimulating hormone, but not luteinizing hormone, increased LPS-stimulated granulosa cell inflammation, and follicle-stimulating hormone increased SCARB1 protein. However, changes in inflammation were not associated with changes in oestradiol or progesterone secretion. Taken together these findings imply that cholesterol supports inflammatory responses to LPS in granulosa cells.

Bovine models for human ovarian diseases

During early embryonic development, late fetal growth, puberty, adult reproductive years, and advanced aging, bovine and human ovaries closely share molecular pathways and hormonal signaling mechanisms. Other similarities between these species include the size of ovaries, length of gestation, ovarian follicular and luteal dynamics, and pathophysiology of ovarian diseases. As an economically important agriculture species, cattle are a foundational species in fertility research with decades of groundwork using physiologic, genetic, and therapeutic experimental techniques. Many technologies used in modern reproductive medicine, such as ovulation induction using hormonal therapy, were first used in cows before human trials. Human ovarian diseases with naturally occurring bovine correlates include premature ovary insufficiency (POI), polycystic ovarian syndrome (PCOS), and sex-cord stromal tumors (SCSTs). This article presents an overview of bovine ovary research related to causes of infertility, ovarian diseases, diagnostics, and therapeutics, emphasizing where the bovine model can offer advantages over other lab animals for translational applications.

Effects of bone morphogenetic protein 4, gremlin, and connective tissue growth factor on estradiol and progesterone production by bovine granulosa cells

Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-β family of proteins that have been implicated in the paracrine regulation of granulosa cell (GC) function, but whether responses to BMPs change with follicular size or interact with connective tissue growth factor (CTGF) or BMP antagonists (e.g., gremlin [GREM]) to directly affect GC function of cattle is unknown. Therefore, to determine the effects of BMP4 on proliferation and steroidogenesis of GCs and its interaction with GREM or CTGF, experiments were conducted using bovine GC cultures. In vitro, BMP4 (30 ng/mL) inhibited (P < 0.05) follicle-stimulating hormone (FSH) plus insulin-like growth factor 1 (IGF1)-induced progesterone and estradiol production by large- and small-follicle GCs, but the inhibitory effect of BMP4 on estradiol production was much more pronounced in large-follicle GCs. In small-follicle GCs, BMP4 had no effect (P > 0.10) on IGF1-induced proliferation, but GREM inhibited (P < 0.05) cell proliferation and estradiol and progesterone production in IGF1 plus FSH-treated GCs. In large-follicle GCs, BMP4 (10 to 30 ng/mL) increased (P < 0.05) GC numbers and GREM (100 ng/mL) blocked this effect. In large-follicle GCs, CTGF inhibited (P < 0.05) FSH plus IGF1-induced progesterone and estradiol production, and CTGF blocked the stimulatory effect of BMP4 on GC proliferation. These results indicate that BMP4, GREM, and CTGF inhibit GC aromatase activity and progesterone production. Also, the stimulatory effect of BMP4 on GC proliferation and the inhibitory effects of BMP4 on GC steroidogenesis are more pronounced in large vs. small follicles.

The Role of Bone Morphogenetic Protein 4 in Ovarian Function and Diseases

Bone morphogenetic proteins (BMPs) are the largest subfamily of the transforming growth factor-β (TGF-β) superfamily. BMP4 is a secreted protein that was originally identified due to its role in bone and cartilage development. Over the past decades, extensive literature has indicated that BMP4 and its receptors are widely expressed in the ovary. Dysregulation of BMP4 expression may play a vital role in follicular development, polycystic ovary syndrome (PCOS), and ovarian cancer. In this review, we summarized the expression pattern of BMP4 in the ovary, focused on the role of BMP4 in follicular development and steroidogenesis, and discussed the role of BMP4 in ovarian diseases such as polycystic ovary syndrome and ovarian cancer. Some studies have shown that the expression of BMP4 in the ovary is spatiotemporal and species specific, but the effects of BMP4 seem to be similar in follicular development of different species. In addition, BMP4 is involved in the development of hyperandrogenemia in PCOS and drug resistance in ovarian cancer, but further research is still needed to clarify the specific mechanisms.

Transcriptomic analysis of gene expression in normal goat ovary and intersex goat gonad

Intersexuality is a congenital reproductive disorder that usually occurs in hornless goats, hindering breeding of goats with hornless traits and the development of the goat industry. In this study, we aimed to identify differentially expressed genes in intersex and normal goat gonads by comparing gene transcription profiles of intersex and normal goat gonads. As intersex goats are genetically based on females, we chose female goats as controls. The goats in the control group and the experimental group were both over one-year old. We evaluated the anatomical characteristics of the reproductive organs of five intersex goats using histopathological methods. The gonads were found to be ovarian and testicular types. RNA-Seq technology was used to identify differentially expressed genes in gonads and normal goat ovary tissues. Transcription analysis results were verified by qPCR. The results showed that 2,748 DEGs were upregulated and 3,327 DEGs were downregulated in intersex ovaries unlike in controls, whereas 2006 DEGs were upregulated and 2032 DEGs were downregulated in the interstitial testes. Many of these genes play important roles in mammalian sex determination and sex differentiation, such as SOX9, WT1, GATA4, DMRT1, DHH, AMH, CYP19A1 and FST. We found that many DEGs are involved in biological developmental regulation by GO and KEGG enrichment analyses, and that most genes associated with the steroid synthesis pathway were downregulated. The DEGs identified in this study may be involved in the regulation of intersex goat sex determination and differentiation, and may increase our understanding of the molecular mechanisms of mammalian sex differentiation.

Transforming growth factor-beta family members are regulated during induced luteolysis in cattle

The transforming growth factors beta (TGFβ) are local factors produced by ovarian cells which, after binding to their receptors, regulate follicular deviation and ovulation. However, their regulation and function during corpus luteum (CL) regression has been poorly investigated. The present study evaluated the mRNA regulation of some TGFβ family ligands and their receptors in the bovine CL during induced luteolysis in vivo. On day 10 of the estrous cycle, cows received an injection of prostaglandin F2α (PGF) and luteal samples were obtained from separate groups of cows (n= 4-5 cows per time-point) at 0, 2, 12, 24 or 48 h after treatment. Since TGF beta family comprises more than 30 ligands, we focused in some candidates genes such as activin receptors (ACVR-1A, -1B, -2A, -2B) AMH, AMHR2, BMPs (BMP-1, -2, -3, -4, -6 and -7), BMP receptors (BMPR-1A, -1B and -2), inhibin subunits (INH-A, -BA, -BB) and betaglycan (TGFBR3). The mRNA levels of BMP4, BMP6 and INHBA were higher at 2 h after PGF administration (P<0.05) in comparison to 0 h. The relative mRNA abundance of BMP1, BMP2, BMP3, BMP4, BMP6, ACVR1B, INHBA and INHBB was upregulated up to 12 h post PGF (P<0.05). On the other hand, TGFBR3 mRNA that codes for a reservoir of ligands that bind to TGF-beta receptors, was lower at 48 h. In conclusion, findings from this study demonstrated that genes encoding several TGFβ family members are expressed in a time-specific manner after PGF administration.

Comparative analysis of differentially expressed genes between the ovaries from pregnant and nonpregnant goats using RNA-Seq

Background

A multitude of genes tightly regulate ovarian follicular development and hormone secretion. These complex and coordinated biological processes are altered during pregnancy. In order to further understand the regulatory role of these genes during pregnancy, it is important to screen the differentially expressed genes (DEGs) in the ovaries of pregnant and nonpregnant mammals. To detect the genes associated with the development of pregnancy in goats, DEGs from the ovaries from pregnant and nonpregnant Anhui white goats (pAWGs and nAWGs, respectively) were analyzed using RNA sequencing technology (RNA-Seq).

Results

In this study, 13,676,394 and 13,549,560 clean reads were generated from pAWGs and nAWGs, respectively, and 1724 DEGs were identified between the two libraries. Compared with nAWGs, 1033 genes were upregulated and 691 genes were downregulated in pAWGs, including PGR, PRLR, STAR and CYP19A1, which play important roles in goat reproduction. Gene Ontology analysis showed that the DEGs were enriched for 49 functional GO terms. Kyoto Encyclopedia of Genes and Genomes analysis revealed that 397 DEGs were significantly enriched in 13 pathways, including “cell cycle”, “cytokine–cytokine receptor interaction” and “steroid biosynthesis”, suggesting that the genes may be associated with cell cycle regulation, follicular development and hormone secretion to regulate the reproduction process. Additionally, quantitative real-time PCR was used to verify the reliability of the RNA-Seq data.

Conclusions

The data obtained in this work enrich the genetic resources of goat and provide a further understanding of the complex molecular regulatory mechanisms occurring during the development of pregnancy and reproduction in goats. The DEGs screened in this study may play an important role in follicular development and hormone secretion and they would provide scientific basis for related research in the future.

Electronic supplementary material

The online version of this article (10.1186/s40709-019-0095-9) contains supplementary material, which is available to authorized users.

Genome-wide differential mRNA expression profiles in follicles of two breeds and at two stages of estrus cycle of gilts

Estrus expression by gilts and sows is hereditable and important for heat detection. To better understand the molecular biological mechanisms of estrus expression in gilts, the mRNA expression profiles of follicular tissue from Large White gilts in diestrus (LD, n = 3) and estrus (LE, n = 3), and Chinese indigenous Mi gilts in diestrus (MD, n = 2) and estrus (ME, n = 3) were investigated using RNA sequencing. We detected 122,804-335,295 SNPs, 6,140-14,947 InDel and 12 types of AS events (39.57% TSS, 34.90% TTS) in 11 samples. A total of 2,838 differentially expressed genes (DEGs) were found in LD vs MD, LE vs ME, LE vs LD, or ME vs MD comparisons. Two DEGs (ACP5 and PIGS) were observed in all comparisons. Two new genes (ENSSSCG00000028235 and ENSSSCG00000021903) were exclusively expressed in Mi and Large White gilts, respectively. Bioinformatics analyses indicate that these DEGs are involved in single-organism process, catalytic activity, cell adhesion and enriched in ECM-receptor interaction, olfactory transduction, ovarian steroidogenesis, steroid biosynthesis and CAMs signaling pathways. These results of RNA-Seq have provided important information for screening the key functional genes or molecular markers of estrus expression in gilts.

Relationship between in vitro growth of bovine oocytes and steroidogenesis of granulosa cells cultured in medium supplemented with bone morphogenetic protein-4 and follicle stimulating hormone

Bone morphogenetic protein-4 (BMP-4) and FSH play important regulatory roles in follicular growth and steroidogenesis in vivo. The purpose of this study was to investigate the effects of BMP-4 and FSH on in vitro growth (IVG) and steroidogenesis of bovine oocyte-cumulus-granulosa complexes (OCGCs). We cultured OCGCs collected from early antral follicles (0.5-1 mm) in medium without BMP-4 and FSH for 4 days and investigated the appearance of OCGCs and their steroidogenesis. During the first 4 days of IVG, morphologically normal OCGCs produced more estradiol-17β (E₂), but less progesterone (P₄). Morphologically normal OCGCs were subjected to an additional culture in medium supplemented with BMP-4 (0, 10, and 50 ng/mL) and FSH (0 and 0.5 ng/mL) until day 12. We examined the viability and steroidogenesis of OCGCs after 8 and 12 days of culture. Oocyte growth, characteristics of granulosa cells, and the maturational competence of oocytes were also investigated. On day 8, the viability of OCGCs cultured without FSH was higher in the 10 ng/mL BMP-4 group than in the 50 ng/mL BMP-4 group (P < 0.05). No significant difference was observed in the viability of groups cultured with FSH, regardless of the addition of BMP-4, and FSH improved the viability of 50 ng/mL BMP-4 group similar to 10 ng/mL BMP-4 group. The total number of granulosa cells was larger in 10 ng/mL BMP-4 group cultured with FSH than in 50 ng/mL BMP-4 group cultured with FSH on day 8 (P < 0.05). E₂ production decreased from days 8-12, and P₄ production increased throughout IVG culture, regardless of the addition of BMP-4 and FSH (P < 0.05). No significant differences in E₂ production were observed between groups from days 4-8, regardless of whether BMP-4 was added without FSH; however, E₂ production in the group cultured with 50 ng/mL BMP-4 was suppressed by FSH. BMP-4 suppressed E₂ production from days 8-12, regardless of whether FSH was added. The group cultured with 10 ng/mL BMP-4 without FSH showed the lowest P₄ production among all groups for all culture periods. OCGCs that produced mature oocytes tended to secrete more E₂ and less P₄ than OCGCs that produced immature oocytes. In conclusion, until day 8 of the IVG culture, P₄ production by OCGCs was suppressed by the addition of 10 ng/mL BMP-4 in the absence of FSH, without inhibiting E₂ production. These conditions appear to mimic growing follicles until day 8 and mimic degenerating follicles from days 8-12 of culture.

Alcohol Exposure Causes Overexpression of Heart Development-Related Genes by Affecting the Histone H3 Acetylation via BMP Signaling Pathway in Cardiomyoblast Cells

BACKGROUND

Abusive alcohol utilization of pregnant woman may cause congenital heart disease (CHD) of fetus, where alcohol ignites histone H3 hyperacetylation leading to abnormal development of heart morphogenesis and associated genes. Knowledge about the regularized upstream genes is little, but bone morphogenetic protein (BMP) signaling may actively and prominently take part in alteration in acetylation of histone H3. The supreme objective of this study was to unearth the involvement of BMP signaling pathway in alcohol-driven hyperacetylation of histone H3 in cardiomyoblast cells.

METHODS

Cardiomyoblast cells (H9c2 cells) were addicted with alcohol (100 mM) for 24 hours. Dorsomorphin (5 μM) was used for the inhibition of BMP signaling pathway. We detected the phosphorylation activity of SMAD1/5/8, mRNA expression, histone acetyltransferases (HAT)/histone deacetylase (HDAC) activity, and acetylation of histone H3.

RESULTS

Following alcohol exposure, phosphorylation of SMAD1/5/8 and HAT activities was increased to a significant extent, while histone H3 acetylation and expression of heart development-related genes were also increased. The said phenomenon influenced by alcohol was reverted upon dorsomorphin treatment to the cells without effecting HDAC activity.

CONCLUSIONS

The data clearly identified that BMP-mediated histone H3 acetylation of heart development-related genes might be one of the possible cellular mechanisms to control alcohol-induced expression of heart development-related genes. Dorsomorphin, on the other hand, may modulate alcohol-induced hyperacetylation of histone H3 through BMP targeting, which could be a potential way to block CHD.

Exposure of preimplantation embryos to low-dose bisphenol A impairs testes development and suppresses histone acetylation of StAR promoter to reduce production of testosterone in mice

Previous studies have shown that bisphenol A (BPA) is a potential endocrine disruptor and testicular toxicant. The present study focused on exploring the impact of exposure to low dose of BPA on male reproductive development during the early embryo stage and the underlying mechanisms. BPA (20 μg/kg/day) was orally administered to female mice on days 1-5 of gestation. The male offspring were euthanized at PND10, 20, 24, 35 or PND50. We found that the mice exposed to BPA before implantation (BPA-mice) displayed retardation of testicular development with reduction of testosterone level. The diameter and epithelium height of seminiferous tubules were reduced in BPA-mice at PND35. The numbers of spermatogenic cells at different stages were significantly reduced in BPA-mice at PND50. BPA-mice showed a persistent reduction in serum and testicular testosterone levels starting from PND24, whereas GnRH mRNA was significantly increased at PND35 and PND50. The expressions of testicular StAR and P450scc in BPA-mice also decreased relative to those of the controls at PND35 and PND50. Further analysis found that the levels of histone H3 and H3K14 acetylation (Ac-H3 and H3K14ac) in the promoter of StAR were decreased relative to those of control mice, whereas the level of Ac-H3 in the promoter of P450scc was not significantly different between the groups. These results provide evidence that exposure to BPA in preimplantation embryo retards the development of testes by reducing histone acetylation of the StAR promoter to disrupt the testicular testosterone synthesis.

CMKLR1 deficiency maintains ovarian steroid production in mice treated chronically with dihydrotestosterone

Elevated serum chemerin levels correlate with increased severity of polycystic ovary syndrome (PCOS). However, the role of CMKLR1 signaling in ovarian biology under conditions of excess DHT remains unclear. In this study we compared the effects of continuous 90-day high dose DHT exposure (83.3 □g/day) on wild type and CMKLR1-deficient mice. DHT induced PCOS-like clinical signs in wild type mice as well as significant changes in the expression of hormone receptors, steroid synthesis enzymes, and BMPs and their receptors. In contrast, CMKLR1-deficient mice significantly attenuated DHT-induced clinical signs of PCOS and alterations in ovarian gene expression. To determine whether the BMP4 signaling pathway was involved in the pathogenic effects of CMKLR1 signaling in DHT-induced ovarian steroidogenesis, antral follicles were isolated from wild type and CMKLR1 knockout (KO) mice and treated in vitro with combinations of hCG, DHT, and BMP4 inhibitors. BMP4 inhibition attenuated the induction effects of hCG and DHT on estrogen and progesterone secretion in CMKLR1 KO mice, but not in WT mice, implicating the BMP4 signaling pathway in the CMKLR1-dependent response to DHT. In conclusion, CMKLR1 gene deletion attenuates the effects of chronic DHT treatment on ovarian function in experimental PCOS, likely via BMP4 signaling.

Effect of bone morphogenetic protein-4 on in vitro growth, steroidogenesis and subsequent developmental competence of the oocyte-granulosa cell complex derived from bovine early antral follicles

BACKGROUND

Bone morphogenetic proteins (BMPs) play important regulatory roles during folliculogenesis. Theca-derived BMP-4 may be beneficial to in vitro growth culture of early antral follicle-derived oocyte-granulosa cell complexes (OGCs), which is lacking in theca-derived products.

METHODS

BMP-4 (0 [control], 10 and 50 ng/mL) was added to growth culture medium. Growth, steroidogenesis and the subsequent developmental competence of OGCs derived from bovine early antral follicles (0.5-1 mm) were examined.

RESULTS

At 4, 8 and 12 days of growth culture, progesterone production by granulosa cells was suppressed by the addition of BMP-4 compared to the control (P < 0.05). At 12 days, both the OGC survivability and granulosa cell number in the 50 ng/mL BMP-4 treated group were lower than those of control (48.2 % vs. 67.8 %; 4.96 × 10(4) vs. 8.5 × 10(4) cells; P < 0.05, respectively), while no difference was found between 10 ng/mL and the control. The mean diameters of granulosa cell in the BMP-4 treated groups were smaller than that of the control (P < 0.05). However, the granulosa cell viability, oocyte diameter, oocyte nuclear maturation rate and normal fertilization rate were similar in all of the experimental groups, regardless of the amount of BMP-4 addition (P ˃ 0.05). BMP-4 treated in vitro-grown oocytes showed lower blastocyst rates than untreated ones (P < 0.05).

CONCLUSIONS

BMP-4 addition during in vitro growth culture suppressed progesterone production and decreased the diameter of granulosa cells, suggesting its effect on steroidogenesis; importantly, it did not affect oocyte growth, nuclear maturation and fertilization. However, BMP-4 impaired subsequent embryonic development, and in higher concentration (50 ng/mL) even compromised OGC viability by suppressing proliferation of granulosa cells.

BMP4 and BMP7 Suppress StAR and Progesterone Production via ALK3 and SMAD1/5/8-SMAD4 in Human Granulosa-Lutein Cells

Adequate production of progesterone by the corpus luteum is critical to the successful establishment of pregnancy. In animal models, bone morphogenetic protein (BMP) 4 and BMP7 have been shown to suppress either basal or gonadotropin-induced progesterone production, depending on the species examined. However, the effects of BMP4 and BMP7 on progesterone production in human granulosa cells are unknown. In the present study, we used immortalized (SVOG) and primary human granulosa-lutein cells to investigate the effects of BMP4 and BMP7 on steroidogenic acute regulatory protein (StAR) expression and progesterone production and to examine the underlying molecular mechanism. Treatment of primary and immortalized human granulosa cells with recombinant BMP4 or BMP7 decreased StAR expression and progesterone accumulation. In SVOG cells, the suppressive effects of BMP4 and BMP7 on StAR expression were blocked by pretreatment with inhibitors of activin receptor-like kinase (ALK)2/3/6 (dorsomorphin) or ALK2/3 (DMH1) but not ALK4/5/7 (SB-431542). Moreover, small interfering RNA-mediated depletion of ALK3, but not ALK2 or ALK6, reversed the effects of BMP4 and BMP7 on StAR expression. Likewise, BMP4- and BMP7-induced phosphorylation of SMAD 1/5/8 was reversed by treatment with DMH1 or small interfering RNA targeting ALK3. Knockdown of SMAD4, the essential common SMAD for BMP/TGF-β signaling, abolished the effects of BMP4 and BMP7 on StAR expression. Our results suggest that BMP4 and BMP7 down-regulate StAR and progesterone production via ALK3 and SMAD1/5/8-SMAD4 signaling in human granulosa-lutein cells.

Differential gene expression in ovaries of Qira black sheep and Hetian sheep using RNA-Seq technique

The Qira black sheep and the Hetian sheep are two local breeds in the Northwest of China, which are characterized by high-fecundity and low-fecundity breed respectively. The elucidation of mRNA expression profiles in the ovaries among different sheep breeds representing fecundity extremes will helpful for identification and utilization of major prolificacy genes in sheep. In the present study, we performed RNA-seq technology to compare the difference in ovarian mRNA expression profiles between Qira black sheep and Hetian sheep. From the Qira black sheep and the Hetian sheep libraries, we obtained a total of 11,747,582 and 11,879,968 sequencing reads, respectively. After aligning to the reference sequences, the two libraries included 16,763 and 16,814 genes respectively. A total of 1,252 genes were significantly differentially expressed at Hetian sheep compared with Qira black sheep. Eight differentially expressed genes were randomly selected for validation by real-time RT-PCR. This study provides a basic data for future research of the sheep reproduction.

Global gene expression in granulosa cells of growing, plateau and atretic dominant follicles in cattle

BACKGROUND

The physiological state of the dominant follicle is important as it may be linked to the competence of the oocyte within. The objective of this study was to analyze, by transcriptomic analysis, the changes occurring in granulosa cells from dominant follicles at different phases of follicular growth.

METHODS

Granulosa cells were collected from slaughterhouse dairy cattle follicles with a diameter greater than 9 mm, and were classified at different phases of follicle growth based on flow cytometry profiles of DNA content after staining with propidium iodide. Three phases were identified based on the proportion of cells in -G1 (less than 2n DNA), G0-G1 (2n DNA) or S-M (more than 2n DNA) and follicles were thus allocated to the growing, plateau or atresia group. Between group analysis (BGA) showed clear segregation of the three groups, and the groups were contrasted against each other in a loop design to identify differently expressed genes. Ingenuity Pathway Analysis (IPA) was used to identify the functions and upstream regulators associated with the observed differently expressed genes.

RESULTS

Major differences were observed between the growth phases. Granulosa cells from follicles in the plateau phase had increased expression of TYRO3 and downregulation of JAM2 compared to growing follicles, supporting the idea of a shift from proliferation to differentiation. On the other hand, genes regulating the response to oxidative stress (VNN1) and angiogenesis (ANGPT2) were upregulated in granulosa cells from atretic follicles. While the predicted activated functions in cells at the plateau stage compared to cells at the growing stage included synthesis and transport of molecules, the predictions for atretic follicles relative to plateau ones included an increase in apoptosis and cell death.

CONCLUSION

Consistent with previous studies, these observations allowed us to match the presence of specific gene transcripts to a particular physiological status and consequently to classify follicles. The results also demonstrated that the plateau phase is not a simple 'in between' status between growth and atresia, as several characteristics are unique to this stage.

Smad4 mediated BMP2 signal is essential for the regulation of GATA4 and Nkx2.5 by affecting the histone H3 acetylation in H9c2 cells

BMP2 signaling pathway plays critical roles during heart development, Smad4 encodes the only common Smad protein in mammals, which is a pivotal nuclear mediator. Our previous studies showed that BMP2 enhanced the expression of cardiac transcription factors in part by increasing histone H3 acetylation. In the present study, we tested the hypothesis that Smad4 mediated BMP2 signaling pathway is essential for the expression of cardiac core transcription factors by affecting the histone H3 acetylation. We successfully constructed a lentivirus-mediated short hairpin RNA interference vector targeting Smad4 (Lv-Smad4) in rat H9c2 embryonic cardiac myocytes (H9c2 cells) and demonstrated that it suppressed the expression of the Smad4 gene. Cultured H9c2 cells were transfected with recombinant adenoviruses expressing human BMP2 (AdBMP2) with or without Lv-Smad4. Quantitative real-time RT-PCR analysis showed that knocking down of Smad4 substantially inhibited both AdBMP2-induced and basal expression levels of cardiac transcription factors GATA4 and Nkx2.5, but not MEF2c and Tbx5. Similarly, chromatin immunoprecipitation (ChIP) analysis showed that knocking down of Smad4 inhibited both AdBMP2-induced and basal histone H3 acetylation levels in the promoter regions of GATA4 and Nkx2.5, but not of Tbx5 and MEF2c. In addition, Lv-Smad4 selectively suppressed AdBMP2-induced expression of HAT p300, but not of HAT GCN5 in H9c2 cells. The data indicated that inhibition of Smad4 diminished both AdBMP2 induced and basal histone acetylation levels in the promoter regions of GATA4 and Nkx2.5, suggesting that Smad4 mediated BMP2 signaling pathway was essential for the regulation of GATA4 and Nkx2.5 by affecting the histone H3 acetylation in H9c2 cells.

Maternal nutrient restriction in the ewe from early to midgestation programs reduced steroidogenic enzyme expression and tended to reduce progesterone content of corpora lutea, as well as circulating progesterone in nonpregnant aged female offspring

BACKGROUND

Previously we reported decreased circulating progesterone and fertility in one and two year old ewes born to undernourished mothers. This study was designed to investigate if this reduction in progesterone persisted into old age, and if it did, what mechanisms are involved.

METHODS

Ewes were fed a nutrient restricted (NR, 50% of NRC recommendations) or control (C, 100% of NRC) diets from day 28 to 78 of gestation, then all were fed to requirements through parturition and weaning. Female offspring (4 per treatment group) were maintained as a group and fed to requirements from weaning until assigned to this study at 6 years of age. Ewes were synchronized for estrus (day 0) and blood samples were collected daily from day 0 to day 11 before necropsy on day 12. Blood serum and luteal tissue were assayed for progesterone concentrations by validated radioimmunoassay.

RESULTS

Circulation progesterone concentrations tended to be lower (P = 0.06) in NR than C offspring from day 0 to 11 of the estrous cycle. While total luteal weight was similar across groups, total progesterone content also tended to be reduced (P = 0.07) in luteal tissue of NR than C offspring. Activity of hepatic progesterone catabolizing enzymes and selected angiogenic factors in luteal tissue were similar between groups. Messenger RNA expression of steroidogenic enzymes StAR and P450scc were reduced (P < 0.05), while protein expression of StAR tended to be reduced (P < 0.07) and P450scc was reduced (P < 0.05) in luteal tissue of NR versus C offspring.

CONCLUSIONS

There appears to be no difference in hepatic steroid catabolism that could have led to the decreased serum progesterone. However, these data are consistent with the programming of decreased steroidogenic enzyme expression in CL of NR offspring, leading to reduced synthesis and secretion of progesterone.

Bone morphogenetic protein‑2 enhances the expression of cardiac transcription factors by increasing histone H3 acetylation in H9c2 cells

Bone morphogenetic protein (BMP)‑2 induces the expression of cardiac transcription factors during early heart development, however, the underlying mechanisms for this are not clear. Our previous studies indicated that histone acetylation is critical in the regulation of cardiac gene expression. In the present study, the hypothesis that BMP2 enhances the expression of cardiac transcription factors by increasing histone H3 acetylation was tested. Cultured H9c2 rat embryonic cardiac myocytes were transfected with adenoviruses expressing human BMP2 (AdBMP2). Real‑time RT‑PCR, western blotting, chromatin immunoprecipitation (ChIP) and colorimetric assays were employed to determine gene expression, histone H3 acetylation levels and histone acetylase (HAT) activities. The mRNA expression levels of BMP2, GATA4, MEF2C and p300, but not of Tbx5 and GCN5, were significantly upregulated following transfection with AdBMP2. Similarly, the histone H3 acetylation levels were enhanced in the whole chromatin and in the promoter regions of GATA4 and MEF2C, but not Tbx5, in the transfected cells. The HAT activities were also enhanced. These results indicate that BMP2 is able to upregulate the expression of the cardiac transcription factors GATA4 and MEF2C, in part by increasing histone H3 acetylation in the promoter regions of these genes.

Luteinizing hormone (LH) regulates production of androstenedione and progesterone via control of histone acetylation of StAR and CYP17 promoters in ovarian theca cells

Although luteinizing hormone (LH) affects androstenedione (A4) and progesterone (P4) production in theca cells, it is still unknown how LH influences molecular mechanism of A4 and P4 production. To examine the relationship between LH and transcription factors involved in A4 and P4 production, ovarian theca cells were cultured in the presence or absence of high concentrations of LH for 24 h (pre-treatment with high concentration of LH) and then cultured in the presence or absence of low concentration of LH for 48 h. Low LH enhanced production of A4 and P4, and expressions of CYP17 and StAR mRNA in theca cells without pre-treatment with high LH. In addition, low LH stimulated the expression of SF-1 protein in nuclear fractions from theca cells with or without pre-treatment with high LH. The binding of SF-1 to the CYP17 and StAR promoter regions increased in theca cells treated with low LH. Although GATA-4 and GATA-6 are both found in the nuclear fraction but not in the cytosol of theca cells, low LH enhanced the binding of GATA-6, but not of GATA-4, to the CYP17 promoter region without pre-treatment with high LH. Acetylation histone H3 in StAR and CYP17 promoter regions were changed by different LH-dosage. Overall, we showed that LH regulates the production of A4 and P4 by affecting the nuclear localization and switching of transcription factors in theca cells and that target transcription factors involved in steroid production in theca cells are changed by different LH concentration.

Circadian Clock genes Per2 and clock regulate steroid production, cell proliferation, and luteinizing hormone receptor transcription in ovarian granulosa cells

Circadian Clock genes are associated with the estrous cycle in female animals. Treatment with Per2 and Clock siRNAs decreased the number of granulosa cells and LHr expression in follicle-stimulating hormone FSH-treated granulosa cells. Per2 siRNA treatment did not stimulate the production of estradiol and expression of P450arom, whereas Clock siRNA treatment inhibited the production of estradiol and expression of P450arom mRNA. Per2 and Clock siRNA treatment increased and unchanged, respectively, progesterone production in FSH-treated granulosa cells. Similarly, expression of StAR mRNA was increased by Per2 siRNA and unchanged by Clock siRNA. Our data provide a new insight that Per2 and Clock have different action on ovarian granulosa cell functions.