Maternal obese environment has been reported to induce oxidative stress and meiotic defects in oocytes, however the underlying molecular mechanism remains unclear. Here, using mice fed a high fat diet (HFD) as an obesity model, we first detected enhanced reactive oxygen species (ROS) content and reduced Sirt3 expression in HFD oocytes. We further observed that specific depletion of Sirt3 in control oocytes elevates ROS levels while Sirt3 overexpression attenuates ROS production in HFD oocytes, with significant suppression of spindle disorganization and chromosome misalignment phenotypes that have been reported in the obesity model. Candidate screening revealed that the acetylation status of lysine 68 on superoxide dismutase (SOD2K68) is dependent on Sirt3 deacetylase activity in oocytes, and acetylation-mimetic mutant SOD2K68Q results in almost threefold increase in intracellular ROS. Moreover, we found that acetylation levels of SOD2K68 are increased by ~80% in HFD oocytes and importantly, that the non-acetylatable-mimetic mutant SOD2K68R is capable of partially rescuing their deficient phenotypes. Together, our data identify Sirt3 as an important player in modulating ROS homeostasis during oocyte development, and indicate that Sirt3-dependent deacetylation of SOD2 plays a protective role against oxidative stress and meiotic defects in oocytes under maternal obese conditions.

MicroRNAs (miRNAs) are short, noncoding RNAs that posttranscriptionally regulate gene expression. In the past decade, studies on miRNAs in ovaries have revealed the key roles of miRNAs in ovarian development and function. In this review, we first introduce the development of follicular atresia research and then summarize genome-wide studies on the ovarian miRNA profiles of different mammalian species. Differentially expressed miRNA profiles during atresia and other biological processes are herein compared. In addition, current knowledge on confirmed functional miRNAs during the follicular atresia process, which is mostly indicated by granulosa cell (GC) apoptosis, is presented. The main miRNA families and clusters, including the let-7 family, miR-23-27-24 cluster, miR-183-96-182 cluster and miR-17-92 cluster, and related pathways that are involved in follicular atresia are thoroughly summarized. A deep understanding of the roles of miRNA networks will not only help elucidate the mechanisms of GC apoptosis, follicular development, atresia and their disorders but also offer new diagnostic and treatment strategies for infertility and other ovarian dysfunctions.Electronic supplementary materialThe online version of this article (10.1186/s12958-018-0450-y) contains supplementary material, which is available to authorized users.

BackgroundProteomics and bioinformatics may help us better understand the biological adaptations occurring during bovine mastitis. This systems approach also could help identify biomarkers for monitoring clinical and subclinical mastitis. The aim of the present study was to use isobaric tags for relative and absolute quantification (iTRAQ) to screen potential proteins associated with mastitis at late infectious stage.ResultsHealthy and mastitic cows’ mammary gland tissues were analyzed using iTRAQ combined with two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS). Bioinformatics analyses of differentially expressed proteins were performed by means of Gene Ontology, metabolic pathways, transcriptional regulation networks using Blast2GO software, the Dynamic Impact Approach and Ingenuity Pathway Analysis. At a false discovery rate of 5%, a total of 768 proteins were identified from 6,499 peptides, which were matched with 15,879 spectra. Compared with healthy mammary gland tissue, 36 proteins were significantly up-regulated (>1.5-fold) while 19 were significantly down-regulated (<0.67-fold) in response to mastitis due to natural infections with Staphylococci aureus. Up-regulation of collagen, type I, alpha 1 (COL1A1) and inter-alpha (Globulin) inhibitor H4 (ITIH4) in the mastitis-infected tissue was confirmed by Western blotting and Immunohistochemistry.ConclusionThis paper is the first to show the protein expression in the late response to a mastitic pathogen, thus, revealing mechanisms associated with host tissue damage. The bioinformatics analyses highlighted the effects of mastitis on proteins such as collagen, fibrinogen, fibronectin, casein alpha and heparan sulfate proteoglycan 2. Our findings provide additional clues for further studies of candidate genes for mastitis susceptibility. The up-regulated expression of COL1A1 and ITIH4 in the mastitic mammary gland may be associated with tissue damage and repair during late stages of infection.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-839) contains supplementary material, which is available to authorized users.

The sperm flagella 2 (SPEF2) gene is essential for development of normal sperm tail and male fertility. In this study, we characterized first the splice variants, promoter and its methylation, and functional single-nucleotide polymorphisms (SNPs) of the SPEF2 gene in newborn and adult Holstein bulls. Four splice variants were identified in the testes, epididymis, sperm, heart, spleen, lungs, kidneys, and liver tissues through RT-PCR, clone sequencing, and western blot analysis. Immunohistochemistry revealed that the SPEF2 was specifically expressed in the primary spermatocytes, elongated spermatids, and round spermatids in the testes and epididymis. SPEF2-SV1 was differentially expressed in the sperms of high-performance and low-performance adult bulls; SPEF2-SV2 presents the highest expression in testis and epididymis; SPEF2-SV3 was only detected in testis and epididymis. An SNP (c.2851GOT) in exon 20 of SPEF2, located within a putative exonic splice enhancer, potentially produced SPEF2-SV3 and was involved in semen deformity rate and post-thaw cryopreserved sperm motility. The luciferase reporter and bisulfite sequencing analysis suggested that the methylation pattern of the core promoter did not significantly differ between the full-sib bulls that presented hypomethylation in the ejaculated semen and testis. This finding indicates that sperm quality is unrelated to SPEF2 methylation pattern. Our data suggest that alternative splicing, rather than methylation, is involved in the regulation of SPEF2 expression in the testes and sperm and is one of the determinants of sperm motility during bull spermatogenesis. The exonic SNP (c.2851GOT) produces aberrant splice variants, which can be used as a candidate marker for semen traits selection breeding of Holstein bulls.

Sirtuins have been implicated in diverse biological processes, including oxidative stress, energy metabolism, cell migration, and aging. Here, we employed Sirtuin inhibitors, nicotinamide (NAM) and Sirtinol, to investigate their effects on porcine oocyte maturation respectively. The rate of polar body extrusion in porcine oocytes decreased after treatment with NAM and Sirtinol, accompanied with the failure of cumulus cell expansion. We further found that NAM and Sirtinol significantly disrupted oocyte polarity, and inhibited the formation of actin cap and cortical granule-free domain (CGFD). Moreover, the abnormal spindles and misaligned chromosomes were readily detected during porcine oocyte maturation after treatment with NAM and Sirtinol. Together, these results suggest that Sirtuins are involved in cortical polarity and spindle organization in porcine oocytes.

FSH plays a critical role in granulosa cell (GC) proliferation and steroidogenesis through modulation by factors including bone morphogenetic proteins family, which belongs to transforming growth factor b (TGFB) superfamily. TGFBs are the key factors in maintaining cell growth and differentiation in ovaries. However, the interaction of FSH and TGFB on the GCs' proliferation and steroidogenesis remains to be elucidated. In this study, we have investigated the role of SMAD4, a core molecule mediating the intracellular TGFB/SMAD signal transduction pathway, in FSH-mediated proliferation and steroidogenesis of porcine GCs. In this study, SMAD4 was knocked down using interference RNA in porcine GCs. Our results showed that SMAD4-siRNA causes specific inhibition of SMAD4 mRNA and protein expression after transfection. Knockdown of SMAD4 significantly inhibited FSH-induced porcine GC proliferation and estradiol production and changed the expression of cyclin D2, CDK2, CDK4, CYP19a1, and CYP11a1. Thus, these observations establish an important role of SMAD4 in the regulation of the response of porcine GCs to FSH.

No abstract

Background To investigate the correlation between the level of circulating vitamin D and the development of colorectal cancer (CRC) and to clarify the effect and mechanism of vitamin D on the development of CRC. Methods Serum samples from 63 patients with CRC (CRC group) and 61 healthy volunteers (normal group) were collected. Azoxymethane + dextran sodium sulfate‐induced CRC mouse model and dietary models with different doses of vitamin D were established to verify whether vitamin D supplementation could reverse the occurrence and development of CRC at the overall animal level. Intestinal barrier integrity and microbial defense response were evaluated by detection of intestinal flora and expression of related genes. Results In the clinical serum samples, compared with the normal group, the level of 25 (OH) D3 in the CRC group was relatively low (P < 0.01), which was consistent with the clinical situation in mice. Vitamin D deficiency aggravated the deterioration of enteritis and intestinal cancer in CRC mice, whereas the overall condition of CRC mice improved after vitamin D supplementation. Vitamin D has a significant regulatory effect on the homeostasis of the intestinal flora, particularly in the regulation of intestinal probiotics, Akkermansia muciniphila‐mediated colon barrier integrity. Conclusions Vitamin D deficiency is closely related to the high incidence of CRC, and vitamin D supplementation can inhibit the occurrence and development of CRC. Vitamin D plays a role in the reversal of CRC mainly through the regulation of intestinal flora, especially the regulation of A. muciniphila‐mediated colon barrier integrity.