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

Impaired degradation of PLCG1 by chaperone-mediated autophagy promotes cellular senescence and intervertebral disc degeneration

Defects in chaperone-mediated autophagy (CMA) are associated with cellular senescence, but the mechanism remains poorly understood. Here, we found that CMA inhibition induced cellular senescence in a calcium-dependent manner and identified its role in TNF-induced senescence of nucleus pulposus cells (NPC) and intervertebral disc degeneration. Based on structural and functional proteomic screens, PLCG1 (phospholipase C gamma 1) was predicted as a potential substrate for CMA deficiency to affect calcium homeostasis. We further confirmed that PLCG1 was a key mediator of CMA in the regulation of intracellular calcium flux. Aberrant accumulation of PLCG1 caused by CMA blockage resulted in calcium overload, thereby inducing NPC senescence. Immunoassays on human specimens showed that reduced LAMP2A, the rate-limiting protein of CMA, or increased PLCG1 was associated with disc senescence, and the TNF-induced disc degeneration in rats was inhibited by overexpression of Lamp2a or knockdown of Plcg1. Because CMA dysregulation, calcium overload, and cellular senescence are common features of disc degeneration and other age-related degenerative diseases, the discovery of actionable molecular targets that can link these perturbations may have therapeutic value.Abbreviation: ATRA: all-trans-retinoic acid; BrdU: bromodeoxyuridine; CDKN1A/p21: cyclin dependent kinase inhibitor 1A; CDKN2A/p16-INK4A: cyclin dependent kinase inhibitor 2A; CMA: chaperone-mediated autophagy; DHI: disc height index; ER: endoplasmic reticulum; IP: immunoprecipitation; IP3: inositol 1,4,5-trisphosphate; ITPR/IP3R: inositol 1,4,5-trisphosphate receptor; IVD: intervertebral disc; IVDD: intervertebral disc degeneration; KD: knockdown; KO: knockout; Leu: leupeptin; MRI: magnetic resonance imaging; MS: mass spectrometry; N/L: NH4Cl and leupeptin; NP: nucleus pulposus; NPC: nucleus pulposus cells; PI: protease inhibitors; PLC: phospholipase C; PLCG1: phospholipase C gamma 1; ROS: reactive oxygen species; RT-qPCR: real-time quantitative reverse transcription PCR; SA-GLB1/β-gal: senescence-associated galactosidase beta 1; SASP: senescence-associated secretory phenotype; STV: starvation; TMT: tandem mass tag; TNF: tumor necrosis factor; TP53: tumor protein p53; UPS: ubiquitin-proteasome system.

Cyanidin-3-O-glucoside protects Zearalenone-induced in vitro maturation disorders of porcine oocytes by alleviating NOX4-dependent oxidative stress and endoplasmic reticulum stress in cumulus cells

Zearalenone (ZEN) is widely found in foodstuffs and has serious harmful effects on female fertility, especially in pigs. Cyanidin-3-O-glucoside (C3G), a type of anthocyanin, exists in most dark fruits and vegetables; it has many positive dietary effects including as an antioxidant, anti-inflammatory, or anti-apoptotic agent. However, the beneficial effects of C3G alongside ZEN-induced damage in porcine oocytes and the underlying molecular mechanism have not been investigated. In this work, porcine cumulus-oocyte complexes (COCs) were divided into Control (Ctrl), ZEN, ZEN + C3G (Z + C), and C3G, and treated for 44-46 h in vitro. The results showed that C3G could alleviate ZEN-induced disorders of first polar body (PBI) extrusion, abnormalities of spindle assembly, cortical granule distribution, and mitochondrial distribution; these results were produced via restoring transzonal projections (TZPs), and inhibiting nicotinamide adenine dinucleotide phosphate oxidase (NOX4)-dependent oxidative stress and 'glucose regulatory protein 78/protein kinase-like endoplasmic reticulum kinase/α subunit of eukaryotic initiation factor 2α/activating transcription factor 4/C/EBP-homologous protein' (GRP78/PERK/eIF2α/ATF4/CHOP)-mediated endoplasmic reticulum stress (ERS) during oocyte maturation. Moreover, the over-expression of NOX4 in cumulus cells could result in a significant increase in ROS levels and ER fluorescence intensity in oocytes. In conclusion, C3G promoted in vitro maturation of porcine oocytes exposed to ZEN via mitigating NOX4-dependent oxidative stress and ERS in cumulus cells. These results contribute to our comprehension of the molecular mechanisms underlying the protective effects of C3G against ZEN toxicity in porcine oocytes, and they provide a novel theoretical foundation and strategy for future applications of C3G in the improvement of female reproduction.

Long non-coding RNA Loc105611671 promotes the proliferation of ovarian granulosa cells and steroid hormone production upregulation of CDC42

Granulosa cells (GCs) are essential for follicular development, and long non-coding RNAs (LncRNAs) are known to support the maintenance of this process and hormone synthesis in mammals. Nevertheless, the regulatory roles of these lncRNAs within sheep follicular GCs remain largely unexplored. This study delved into the influence of a Loc105611671, on the proliferation and steroid hormone synthesis of sheep ovarian GCs and the associated target genes in vitro. Cell Counting Kit-8 (CCK-8) gain-of-function experiments indicated that overexpression of Loc105611671 significantly boosted GCs proliferation, along with estrogen (E2) and progesterone (P4) levels. Further mechanistic scrutiny revealed that Loc105611671 is primarily localized within the cytoplasm of ovarian granulosa cells and engages in molecular interplay with CDC42. This interaction results in the upregulation of CDC42 protein expression. Moreover, it was discerned that increased CDC42 levels contribute to augmented proliferation of follicular granulosa cells and the secretion of E2 and P4. Experiments involving co-transfection elucidated that the concurrent overexpression of CDC42 and Loc105611671 acted synergistically to potentiate these effects. These findings provide insights into the molecular underpinnings of fecundity in ovine species and may inform future strategies for enhancing reproductive outcomes.

Knockdown of CLAUDIN-6 Inhibited Apoptosis and Induced Proliferation of Bovine Cumulus Cells

This study aims to investigate the effects of CLAUDIN-6 (CLDN6) on cell apoptosis and proliferation of bovine cumulus cells (CCs). Immunofluorescence staining was used to localize CLDN6 protein in CCs. Three pairs of siRNA targeting CLDN6 and one pair of siRNA universal negative sequence as control were transfected into bovine CCs. Then, the effective siRNA was screened by real-time quantitative PCR (RT-qPCR) and Western blotting. The mRNA expression levels of apoptosis related genes (CASPASE-3, BAX and BCL-2) and proliferation related genes (PCNA, CDC42 and CCND2) were evaluated by RT-qPCR in CCs with CLDN6 knockdown. Cell proliferation, apoptosis and cell cycle were detected by flow cytometry with CCK-8 staining, Annexin V-FITC staining and propidium iodide staining, respectively. Results showed that the CLDN6 gene was expressed in bovine CCs and the protein was localized in cell membranes and cytoplasms. After CLDN6 was knocked down in CCs, the cell apoptosis rate significantly decreased and the pro-apoptotic genes BAX and CASPASE-3 were down-regulated significantly, whereas the anti-apoptotic gene BCL-2 was markedly up-regulated (p < 0.05). Additionally, CLDN6 knockdown significantly enhanced cell proliferation of CCs at 72 h after siRNA transfection. The mRNA levels of proliferation-related genes PCNA, CCND2 and CDC42 increased obviously in CCs with CLDN6 knockdown (p < 0.05). After CLDN6 was down-regulated, the percentage of CCs at S phase was significantly increased (p < 0.05). However, there was no remarkable difference in the percentages of cells at the G0/G1 phase and G2/M phase between CCs with or without CLDN6 knockdown (p > 0.05). Therefore, the expression of CLDN6 and its effects on cell proliferation, apoptosis and cell cycle of bovine CCs were first studied. CLDN6 low expression inhibited cell apoptosis, induced cell proliferation and cell cycle arrest of bovine CCs.

Chronic glucocorticoid exposure accelerates Aβ generation and neurotoxicity by activating calcium-mediated CN-NFAT1 signaling in hippocampal neurons in APP/PS1 mice

Glucocorticoid (GC) exposure can lead to deterioration of the structure and function of hippocampal neurons and is closely involved in Alzheimer's disease (AD). Amyloid-β (Aβ) overproduction is an important aspect of AD pathogenesis. Our study mainly investigated the mechanism of chronic GC exposure in accelerating Aβ production in primary cultured hippocampal neurons from APP/PS1 mice. The results indicated that chronic dexamethasone (DEX, 1 μM) significantly accelerated neuronal damage and Aβ accumulation in hippocampal neurons from APP/PS1 mice. Meanwhile, DEX exposure markedly upregulated APP, NCSTN, BACE1 and p-Tau/Tau expression in hippocampal neurons from APP/PS1 mice. Our study also indicated that chronic DEX exposure significantly increased intracellular Ca²⁺ ([Ca²⁺]_i) levels and the expressions of p-PLC, CN and NFAT1 in hippocampal neurons from APP/PS1 mice. We further found that stabilizing intracellular calcium homeostasis with 2-APB (50 μM) and SKF-96365 (10 μM) significantly alleviated neuronal damage and Aβ accumulation in chronic DEX-induced hippocampal neurons from APP/PS1 mice. Additionally, dual luciferase assays showed that NFAT1 upregulated NCSTN transactivation, which was further increased upon DEX treatment. This study suggests that chronic DEX exposure accelerates Aβ accumulation by activating calcium-mediated CN-NFAT1 signaling in hippocampal neurons from APP/PS1 mice, which may be closely related to the acceleration of AD.

Metabolic and antioxidant status during transition is associated with changes in the granulosa cell transcriptome in the preovulatory follicle in high-producing dairy cows at the time of breeding

In this study, we hypothesized that early postpartum (pp) metabolic and oxidative stress conditions in dairy cows (particularly those with severe negative energy balance, NEB) are associated with long-term changes in granulosa cell (GC) functions in the preovulatory follicle at the time of breeding. Blood samples were collected at wk 2 and wk 8 pp from 47 healthy multiparous cows. Follicular fluid (FF) and GC were collected from the preovulatory follicle after estrous synchronization at wk 8. Several metabolic and antioxidant parameters were measured in blood and FF, and their correlations were studied. Subsequently, 27 representative GC samples were selected for RNA sequencing analysis. The GC gene expression data of LH-responsive genes and the estradiol:progesterone ratio in FF were used to identify pre- and post-LH surge cohorts. We compared the transcriptomic profile of subgroups of cows within the highest and lowest quartiles (Q4 vs. Q1) of each parameter, focusing on the pre-LH surge cohort (n = 16, at least 3 in each subgroup). Differentially expressed genes (DEG: adjusted P-value < 0.05, 5% false discovery rate) were determined using DESeq2 analysis and were functionally annotated. Blood and FF β-carotene and vitamin E concentrations at wk 2, but not at wk 8, were associated with the most pronounced transcriptomic differences in the GC, with up to 341 DEG indicative for lower catabolism, increased oxidoreductase activity and signaling cascades that are known to enhance oocyte developmental competence, increased responsiveness to LH, and a higher steroidogenic activity. In contrast, elevated blood NEFA concentrations at wk 2 (and not at wk 8) were associated with a long-term carryover effect detectable in the GC transcriptome at wk 8 (64 DEG). These genes are related to response to lipids and ketones, oxidative stress, and immune responses, which suggests persistent cellular stress and oxidative damage. This effect was more pronounced in cows with antioxidant deficiencies at wk 8 (up to 148 DEG), with more genes involved in oxidative stress-dependent responses, apoptosis, autophagy and catabolic processes, and mitochondrial damage. Interestingly, within the severe NEB cows (high blood NEFA at wk 2), blood antioxidant concentrations (high vs. low) at wk 8 were associated with up to 194 DEG involved in activation of meiosis and other signaling pathways, indicating a better oocyte supportive capacity. This suggests that the cow antioxidant profile at the time of breeding might alleviate, at least in part, the effect of NEB on GC functions. In conclusion, these results provide further evidence that the metabolic and oxidative stress in dairy cows early postpartum can have long-term effects on GC functions in preovulatory follicles at the time of breeding. The interplay between the effects of antioxidants and NEFA illustrated here might be useful to develop intervention strategies to minimize the effect of severe NEB on fertility.

Gene cascade analysis in human granulosa tumor cells (KGN) following exposure to high levels of free fatty acids and insulin

Maternal metabolic disorders such as obesity and diabetes are detrimental factors that compromise fertility and the success rates of medically assisted procreation procedures. During metabolic stress, adipose tissue is more likely to release free fatty acids (FFA) in the serum resulting in an increase of FFA levels not only in blood, but also in follicular fluid (FF). In humans, high concentrations of palmitic acid and stearic acid reduced granulosa cell survival and were associated with poor cumulus-oocyte complex (COC) morphology. Obesity and high levels of circulating FFA were also causatively linked to hampered insulin sensitivity in cells and compensatory hyperinsulinemia. To provide a global picture of the principal upstream signaling pathways and genomic mechanisms involved in this metabolic context, human granulosa-like tumor cells (KGN) were treated with a combination of palmitic acid, oleic acid, and stearic acid at the higher physiological concentrations found in the follicular fluid of women with a higher body mass index (BMI) (≥ 30.0 kg/m2). We also tested a high concentration of insulin alone and in combination with high concentrations of fatty acids. Transcription analysis by RNA-seq with a cut off for fold change of 1.5 and p-value 0.05 resulted in thousands of differentially expressed genes for each treatment. Using analysis software such as Ingenuity Pathway Analysis (IPA), we were able to establish that high concentrations of FFA affected the expression of genes mainly related to glucose and insulin homoeostasis, fatty acid metabolism, as well as steroidogenesis and granulosa cell differentiation processes. The combination of insulin and high concentrations of FFA affected signaling pathways related to apoptosis, inflammation, and oxidative stress. Taken together, our results provided new information on the mechanisms that might be involved in human granulosa cells exposed to high concentrations of FFA and insulin in the contexts of metabolism disorders.

Simulated Microgravity Induces the Proliferative Inhibition and Morphological Changes in Porcine Granulosa Cells

Astronauts are always faced with serious health problems during prolonged spaceflights. Previous studies have shown that weightlessness significantly affects the physiological function of female astronauts, including a change in reproductive hormones and ovarian cells, such as granulosa and theca cells. However, the effects of microgravity on these cells have not been well characterized, especially in granulosa cells. This study aimed to investigate the effects of simulated microgravity (SMG) on the proliferation and morphology of porcine granulosa cells (pGCs). pGC proliferation from the SMG group was inhibited, demonstrated by the reduced O.D. value and cell density in the WST-1 assay and cell number counting. SMG-induced pGCs exhibited an increased ratio of cells in the G0/G1 phase and a decreased ratio of cells in the S and G2/M phase. Western blot analysis indicated a down-regulation of cyclin D1, cyclin-dependent kinase 4 (cdk4), and cyclin-dependent kinase 6 (cdk6), leading to the prevention of the G1-S transition and inducing the arrest phase. pGCs under the SMG condition showed an increase in nuclear area. This caused a reduction in nuclear shape value in pGCs under the SMG condition. SMG-induced pGCs exhibited different morphologies, including fibroblast-like shape, rhomboid shape, and pebble-like shape. These results revealed that SMG inhibited proliferation and induced morphological changes in pGCs.

Advances in the study of CDC42 in the female reproductive system

CDC42 is a member of the Rho‐GTPase family and is involved in a variety of cellular functions including regulation of cell cycle progression, constitution of the actin backbone and membrane transport. In particular, CDC42 plays a key role in the establishment of polarity in female vertebrate oocytes, and essential to this major regulatory role is its local occupation of specific regions of the cell to ensure that the contractile ring is assembled at the right time and place to ensure proper gametogenesis. The multifactor controlled ‘inactivation‐activation’ process of CDC42 also allows it to play an important role in the multilevel signalling network, and the synergistic regulation of multiple genes ensures maximum precision during gametogenesis. The purpose of this paper is to review the role of CDC42 in the control of gametogenesis and to explore its related mechanisms, with the aim of further understanding the great research potential of CDC42 in female vertebrate germ cells and its future clinical translation.

Isorhamnetin Promotes Estrogen Biosynthesis and Proliferation in Porcine Granulosa Cells via the PI3K/Akt Signaling Pathway

Isorhamnetin is a natural flavonoid widely distributed in fruits and vegetables. However, the roles of isorhamnetin involved in steroidogenesis, proliferation, and apoptosis in ovarian granulosa cells (GCs) are poorly understood. We found that isorhamnetin promoted the secretion of estrogen and inhibited the secretion of progesterone and testosterone by modulating steroidogenesis-associated proteins and mRNA such as CYP19A1, StAR, and 3β-HSD in ovarian GCs. Mechanistically, isorhamnetin stimulated the expression of the proliferating cell nuclear antigen and C-myc and promoted the proliferation of GCs via the PI3K/Akt signaling pathway. Furthermore, isorhamnetin increased the protein expression of CyclinB, CyclinD, CyclinE, and CyclinA, thereby raising the ratio of S-phase cells in response to GC proliferation. Changes in the expression of apoptosis-associated proteins (Bcl2, Bax, and cytochrome c) and intracellular reactive oxygen species levels showed that isorhamnetin inhibited GC apoptosis. Collectively, these findings indicate that isorhamnetin regulates steroidogenesis through the activation of PI3K/Akt, which promotes proliferation, inhibits apoptosis, and alleviates oxidative stress.