Transforming growth factor B1 stimulated DNA synthesis in the granulosa cells of preantral follicles: negative interaction with epidermal growth factor

Transcriptome analysis reveals transforming growth factor-β1 prevents extracellular matrix degradation and cell adhesion during the follicular-luteal transition in cows

Ovarian angiogenesis is an extremely rapid process that occurs during the transition from follicle to corpus luteum (CL) and is crucial for reproduction. It is regulated by numerous factors including transforming growth factor-β1 (TGFB1). However, the regulatory mechanism of TGFB1 in ovarian angiogenesis is not fully understood. To address this, in this study we obtained high-throughput transcriptome analysis (RNA-seq) data from bovine luteinizing follicular cells cultured in a system mimicking angiogenesis and treated with TGFB1, and identified 455 differentially expressed genes (DEGs). Quantitative real-time PCR results confirmed the differential expression patterns of the 12 selected genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified that the MAPK and ErbB pathways, cell adhesion molecules (CAMs), and extracellular matrix (ECM)-receptor interactions may play pivotal roles in TGFB1-mediated inhibition of CL angiogenesis. TGFB1 phosphorylated ERK1/2 (MAPK1/3) and Akt, indicating that these pathways may play an important role in the regulation of angiogenesis. Several genes with specific functions in cell adhesion and ECM degradation were identified among the DEGs. In particular, TGFB1-induced upregulation of syndecan-1 (SDC1) and collagen type I alpha 1 chain (COL1A1) expression may contribute to the deposition of type I collagen in luteinizing follicular cells. These results indicate that TGFB1 inhibits cell adhesion and ECM degradation processes involving ERK1/2, ErbB, and PI3K/Akt signaling pathways, and leads to inhibition of angiogenesis during the follicular-luteal transition. Our results further reveal the molecular mechanisms underlying the actions of TGFB1 in early luteinization.

Docosahexaenoic acid (DHA) effects on proliferation and steroidogenesis of bovine granulosa cells

BACKGROUND

Docosahexaenoic acid (DHA) is a n-3 polyunsaturated fatty acid (PUFA) belonging to a family of biologically active fatty acids (FA), which are known to have numerous health benefits. N-3 PUFAs affect reproduction in cattle, and notably directly affect follicular cells. In terms of reproduction in cattle, n-3 PUFA-enriched diets lead to increased follicle size or numbers.

METHODS

The objective of the present study was to analyze the effects of DHA (1, 10, 20 and 50 μM) on proliferation and steroidogenesis (parametric and/or non parametric (permutational) ANOVA) of bovine granulosa cells in vitro and mechanisms of action through protein expression (Kruskal-Wallis) and signaling pathways (non parametric ANOVA) and to investigate whether DHA could exert part of its action through the free fatty acid receptor 4 (FFAR4).

RESULTS

DHA (10 and 50 μM) increased granulosa cell proliferation and DHA 10 μM led to a corresponding increase in proliferating cell nuclear antigen (PCNA) expression level. DHA also increased progesterone secretion at 1, 20 and 50 μM, and estradiol secretion at 1, 10 and 20 μM. Consistent increases in protein levels were also reported for the steroidogenic enzymes, cytochrome P450 family 11 subfamily A member 1 (CYP11A1) and hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerase 1 (HSD3B1), and of the cholesterol transporter steroidogenic acute regulatory protein (StAR), which are necessary for production of progesterone or androstenedione. FFAR4 was expressed in all cellular types of bovine ovarian follicles, and in granulosa cells it was localized close to the cellular membrane. TUG-891 treatment (1 and 50 μM), a FFAR4 agonist, increased granulosa cell proliferation and MAPK14 phosphorylation in a similar way to that observed with DHA treatment. However, TUG-891 treatment (1, 10 and 50 μM) showed no effect on progesterone or estradiol secretion.

CONCLUSIONS

These data show that DHA stimulated proliferation and steroidogenesis of bovine granulosa cells and led to MAPK14 phosphorylation. FFAR4 involvement in DHA effects requires further investigation, even if our data might suggest FFAR4 role in DHA effects on granulosa cell proliferation. Other mechanisms of DHA action should be investigated as the steroidogenic effects seemed to be independent of FFAR4 activation.

Effects of Smad3 on the proliferation and steroidogenesis in human ovarian luteinized granulosa cells

Granulosa cells (GCs) are essential for proper oocyte, follicular development, and steroidogenesis in the ovary. Transforming growth factor β (TGF-β) superfamily members are critical in regulating GCs growth and differentiation. Smad3 is known to serve as a signaling intermediate for the TGF-β; however, the functions of Smad3 in the human GCs remain unidentified. In this study, the luteinized GCs collected from follicular aspirates from patients undergoing in vitro fertilization were cultured and engineered to overexpress and knockdown Smad3, which were validated by RT-PCR and Western blotting. Immunocytochemistry showed that Smad3 protein was strongly expressed in human ovarian luteinized GCs. EdU incorporation demonstrated that Smad3 promoted the proliferation of GCs, and the expression of PCNA was also enhanced by Smad3. ELISA analysis indicated that the secretion of both estradiol and progesterone was stimulated by Smad3. In addition, Smad3 upregulated the level of follicle-stimulating hormone receptor (FSHR), luteinizing hormone receptor (LHR), and protein kinase A (PKA) proteins. We subsequently added special PKA inhibitor H89 into the GCs and found that the stimulating effect on the growth of GCs by Smad3 was blocked partly. The morphology of cultured GCs was changed by Smad3, and the expression level of integrin β1 was enhanced by Smad3. Kindlin-2, an important cellular mediating molecule of integrin β signaling, was expressed in human ovarian luteinized GCs and was upregulated by Smad3. Our results indicated that Smad3 promoted the proliferation and steroidogenesis of human ovarian luteinized GCs, and these effects may be mediated by the FSHR/LHR-PKA signaling pathway.

SMAD3 regulates the diverse functions of rat granulosa cells relating to the FSHR/PKA signaling pathway

The function of Smad3, a downstream signaling protein of the transforming growth factor β (TGFβ) pathway, in ovarian follicle development remains to be elucidated. The effects of Smad3 on ovarian granulosa cells (GCs) in rat were studied. Female rats (21 days of age Sprague-Dawley) received i.p. injections of pregnant mare serum gonadotropin, and GCs were harvested for primary culture 48 h later. These cells were engineered to overexpress or knockdown Smad3, which were validated by immunohistochemistry and western blot. The expression of proliferating cell nuclear antigen (PCNA), cyclin D2, TGFβ receptor II (TGFβRII), protein kinase A (PKA), and FSH receptor (FSHR) was also detected by western blotting. Cell cycle and apoptosis of GCs were assayed by flow cytometry. The level of estrogen secreted by GCs was detected by ELISA. Smad3 overexpression promoted estrogen production and proliferation while inhibiting apoptosis of GCs. Reduction in Smad3 by RNAi resulted in reduced estrogen production and proliferation and increased apoptosis of GCs. Manipulation of Smad3 expression also resulted in changes in FSHR and PKA expression, suggesting that the effects of Smad3 on follicle development are related to FSHR-mediated cAMP signaling.

Crosstalk between Smad and Mitogen-Activated Protein Kinases for the Regulation of Apoptosis in Cyclosporine A- Induced Renal Tubular Injury

Background/Aims

It remains elusive whether there is a crosstalk between Smad and mitogen-activated protein kinases (MAPKs) and whether it regulates cyclosporine A (CyA)-induced apoptosis in renal proximal tubular cells (RPTCs).

Methods

The effect of CyA on nuclear translocation of Smad2/3 and MAPKs (measured by Western blotting or immunofluorescence) and apoptosis (determined by Hoechst 33258 staining) was examined in HK-2 cells.

Results

CyA induced apoptosis at 24 h and nuclear translocation of phosphorylated (p)-Smad2/3 at 3 h, which was continued till 24 h. CyA enhanced the expression of p-ERK at 1 h, which was continued till 24 h, and of p-p38MAPK at 1–6 h, which returned to control level at 12 h. CyA did not affect JNK. An inhibitor of ERK, PD98059, prevented CyA-induced nuclear translocation of Smad2/3 and apoptosis. An inhibitor of p38MAPK, SB202190, deteriorated CyA-induced nuclear translocation of p-Smad2/3. Epidermal growth factor (EGF) activated ERK and p38MAPK but not JNK. EGF-induced activation of MAPKs ameliorated CyA-induced nuclear translocation of p-Smad2/3 and apoptosis. Inhibition of p38MAPK but not of ERK abolished the protective effect of EGF on CyA-induced nuclear translocation of p-Smad2/3 and apoptosis.

Conclusion

Crosstalk between R-Smad and p38MAPK/ERK, but not JNK differentially regulates apoptosis in CyA-induced RPTC injury.

Signalling pathways involved in the cooperative effects of ovine and murine GDF9+BMP15-stimulated thymidine uptake by rat granulosa cells

Growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are oocyte-secreted factors known to be involved in regulating the proliferation and differentiation of granulosa cells during follicular growth. The aims of this study were to determine the signalling pathways used by recombinant forms of murine and ovine GDF9 and BMP15 in combination (GDF9+BMP15) and the molecular complexes formed by combinations of these factors. Differences in the molecular forms of combinations of murine and ovine GDF9+BMP15 were observed by western blot analysis. Ovine GDF9+BMP15-stimulated (3)H-thymidine uptake was completely blocked by SMAD2/3 and nuclear factor-κB pathway inhibitors and partially blocked by a p38-mitogen-activated protein kinase (MAPK) inhibitor. Thymidine uptake by murine GDF9+BMP15 was reduced by the SMAD2/3 and extracellular signal-regulated kinase-MAPK pathway inhibitors and increased after addition of a c-Jun N-terminal kinase inhibitor. Stimulation of (3)H-thymidine uptake by GDF9+BMP15 from either species was not affected by the SMAD1/5/8 pathway inhibitor. In conclusion, both murine and ovine GDF9+BMP15-stimulated thymidine incorporation in rat granulosa cells was dependent on the SMAD2/3 signalling pathway but not the SMAD1/5/8 pathway. Divergence in the non-SMAD signalling pathways used by murine and ovine GDF9+BMP15 was also evident and may be due to the differences observed in the molecular complexes formed by these factors. These results are consistent with the hypothesis that the disparate cooperative functions of GDF9 and BMP15 in different species are mediated by divergent non-SMAD signalling pathways.

Effects of growth differentiation factor 9 on cell cycle regulators and ERK42/44 in human granulosa cell proliferation

GDF-9 stimulates granulosa cell proliferation and plays important roles during folliclogenesis. However, its molecular mechanisms are still far from clear, particularly its roles in human granulosa cells around the periovulatory stage. Therefore, we investigated the effects of GDF-9 on cell cycle distribution, regulatory molecules, and signaling pathways involved in human luteinized granulosa (hLG) cells in vitro. Primary cultures of hLG cells obtained from women undergoing IVF and treated with and without recombinant GDF-9 were evaluated with and without a specific inhibitor to activin receptor-like kinase 5 (ALK5; SB-431542), ERK42/44 (PD-098059), or Smad3 (SIS3). Cell proliferation, cell cycle distribution, mRNA expression, and protein expression of relevant cell cycle molecules were determined by [(3)H]thymidine incorporation, flow cytometry, quantitative PCR, and immunoblotting, respectively. GDF-9 stimulated [(3)H]thymidine incorporation, enhanced cell transition from G(0)/G(1) to S and G(2)/M phases (whereas both SB-431542 and PD-098059 attenuated these changes), increased mRNA and protein expression of cyclin D(1) and E, and decreased those of the cyclin-dependent kinase (CDK) inhibitors p15(INK4B) and p16(INK4A). GDF-9 also activated Rb protein (a critical G(1) to S-phase regulator), ERK42/44, and Smad3. PD-098059 blocked Rb protein phorsphorylation and the increase in cyclin D(1) and E but not the decrease in p15(INK4B) and p16(INK4A) induced by GDF-9. In contrast, SIS3 reversed the decrease in p15(INK4B) and p16(INK4A) but not the increase in cyclin D(1) and E induced by GDF-9. GDF-9 stimulates hLG cell proliferation by stimulating cyclin D(1) and E and suppressing p15(INK4B) and p16(INK4A) via both Smad-dependent and Smad-independent pathways.

Expression and actions of transforming growth factors during human follicular development

OBJECTIVE

To correlate the temporal expression of transforming growth factor-alpha (TGF-alpha) and TGF-beta genes in granulosa cells (GC) and thecal cells from human follicles at various developmental stages and to determine their trophic effects on GCs.

DESIGN

Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of extracted RNA from follicular GCs and theca cells.

SETTING

Academic endocrinology laboratory.

PATIENT(S)

Premenopausal women undergoing total abdominal hysterectomy and bilateral salpingo-oophorectomy for nonovarian reasons.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Confirmation by the RT-PCR product for TGF-alpha and TGF-beta gene expression in GC and theca cells from human follicles at various developmental stages and (3)H-thymidine uptake in vitro to assess growth effects on GCs.

RESULT(S)

The RT-PCR product indicating the presence of TGF-alpha messenger RNA (mRNA) was found consistently in theca from healthy antral follicles. In theca from large follicles (>1.0 cm) the TGF-alpha PCR product was of reduced intensity. The TGF-alpha was absent or undetectable in granulosa cells from all follicle sizes. The PCR product for TGF-beta was generated by all GC and thecal cell RNAs from all follicle sizes examined. The TGF-alpha promoted and TGF-beta inhibited human GC growth.

CONCLUSION(S)

The presence of TGF-alpha gene expression in thecal cells coincides with periods of follicular growth. The expression of TGF-beta occurs in both cell types throughout antral follicle development. The TGF-alpha and TGF-beta have opposing trophic effects on GCs.

Effects of aging and calorie restriction on the global gene expression profiles of mouse testis and ovary

Background

The aging of reproductive organs is not only a major social issue, but of special interest in aging research. A long-standing view of 'immortal germ line versus mortal soma' poses an important question of whether the reproductive tissues age in similar ways to the somatic tissues. As a first step to understand this phenomenon, we examine global changes in gene expression patterns by DNA microarrays in ovaries and testes of C57BL/6 mice at 1, 6, 16, and 24 months of age. In addition, we compared a group of mice on ad libitum (AL) feeding with a group on lifespan-extending 40% calorie restriction (CR).

Results

We found that gene expression changes occurred in aging gonads, but were generally different from those in somatic organs during aging. For example, only two functional categories of genes previously associated with aging in muscle, kidney, and brain were confirmed in ovary: genes associated with complement activation were upregulated, and genes associated with mitochondrial electron transport were downregulated. The bulk of the changes in gonads were mostly related to gonad-specific functions. Ovaries showed extensive gene expression changes with age, especially in the period when ovulation ceases (from 6 to 16 months), whereas testes showed only limited age-related changes. The same trend was seen for the effects of CR: CR-mediated reversal of age-associated gene expression changes, reported in somatic organs previously, was limited to a small number of genes in gonads. Instead, in both ovary and testis, CR caused small and mostly gonad-specific effects: suppression of ovulation in ovary and activation of testis-specific genes in testis.

Conclusion

Overall, the results are consistent with unique modes of aging and its modification by CR in testis and ovary.