The N6-methyladenosine (m6A) modification plays a central role in epigenetic regulation of the mammalian transcriptome. m6A can be demethylated by the fat mass- and obesity-associated (FTO) protein and the α-ketoglutarate-dependent dioxygenase alkB homolog 5 (ALKBH5) protein. Much less is known about that whether m6A content is involved in POI (premature ovarian insufficiency) disease. In this case-controlled study, 69 POI and 53 tubal occlusion patients were recruited from the reproduction centers in our hospital. For the POI animal model experiment, ovarian tissue was obtained from ten POI and nine healthy mice. An m6A test kit was developed to determine the m6A content in the RNA, and qPCR and western blot were used to examine the mRNA and protein expression levels of FTO and ALKBH5. FACS was used to measure the levels of proliferation and apoptosis, and siRNA was used to establish FTO and ALKBH5 knockdown cell lines. Our results showed that the m6A content in the RNA from POI patients and POI mice was significantly higher than control groups and that POI was characterized by the content of m6A. The mRNA and protein expression levels of FTO were significantly lower in the POI patients than control group and were associated with a risk of POI. These data suggest that the decreased mRNA and protein expression levels of FTO may be responsible for the increase in m6A in POI, which may further increase the risk of complications of POI. High m6A should be investigated further as a novel potential biomarker of POI.

BackgroundAlthough many reports show that various kinds of stem cells have the ability to recover function in premature ovarian aging, few studies have looked at stem cell treatment of natural ovarian aging (NOA). We designed this experimental study to investigate whether human amniotic mesenchymal stem cells (hAMSCs) retain the ability to restore ovarian function, and how hAMSCs work in this process.MethodsTo build the NOA mouse model, the mice were fed for 12–14 months normally with young fertile female mice as the normal control group (3–5 months old). Hematoxylin and eosin staining permitted follicle counting and showed the ovarian tissue structure. An enzyme-linked immunosorbent assay was used to detect the serum levels of the sex hormones estradiol (E2), anti-mullerian hormone (AMH), and follicle-stimulating hormone (FSH). The proliferation rate and marker expression level of human ovarian granule cells (hGCs) (ki67, AMH, FSH receptor, FOXL2, and CYP19A1) were measured by flow cytometry (FACS). Cytokines (growth factors) were measured by a protein antibody array methodology. After hepatocyte growth factor (HGF) and epidermal growth factor (EGF) were co-cultured with hGCs, proliferation (ki67) and apoptosis (Annexin V) levels were analyzed by FACS. After HGF and EGF were injected into the ovaries of natural aging mice, the total follicle numbers and hormone levels were tested.ResultsAfter the hAMSCs were transplanted into the NOA mouse model, the hAMSCs exerted a therapeutic activity on mouse ovarian function by improving the follicle numbers over four stages. In addition, our results showed that hAMSCs significantly promoted the proliferation rate and marker expression level of ovarian granular cells that were from NOA patients. Meanwhile, we found that the secretion level of EGF and HGF from hAMSCs was higher than other growth factors. A growth factor combination (HGF with EGF) improved the proliferation rate and inhibited the apoptosis rate more powerfully after a co-culture with hGCs, and total follicle numbers and hormone levels were elevated to a normal level after the growth factor combination was injected into the ovaries of the NOA mouse model.ConclusionsThese findings provide insight into the notion that hAMSCs play an integral role in resistance to NOA. Furthermore, our present study demonstrates that a growth factor combination derived from hAMSCs plays a central role in inhibiting ovarian aging. Therefore, we suggest that hAMSCs improve ovarian function in natural aging by secreting HGF and EGF.Electronic supplementary materialThe online version of this article (10.1186/s13287-018-0781-9) contains supplementary material, which is available to authorized users.

Bile acids (BAs) have been implicated in regulation of intestinal epithelial signaling and function. This study aimed to investigate the effects of hyodeoxycholic acid (HDCA) on intestinal epithelial cell proliferation and explore the underlying mechanisms. IPEC‐J2 cells and weaned piglets were treated with HDCA and the contributions of cellular signaling pathways, BAs metabolism profiles and gut bacteria were assessed. In vitro, HDCA suppressed IPEC‐J2 proliferation via the BAs receptor FXR but not TGR5. In addition, HDCA inhibited the PI3K/AKT pathway, while knockdown of FXR or constitutive activation of AKT eliminated the inhibitory effects of HDCA, suggesting that FXR‐dependent inhibition of PI3K/AKT pathway was involved in HDCA‐suppressed IPEC‐J2 proliferation. In vivo, dietary HDCA inhibited intestinal expression of proliferative markers and PI3K/AKT pathway in weaned piglets. Meanwhile, HDCA altered the BAs metabolism profiles, with decrease in primary BA and increase in total and secondary BAs in feces, and reduction of conjugated BAs in serum. Furthermore, HDCA increased abundance of the gut bacteria associated with BAs metabolism, and thereby induced BAs profiles alternation, which might indirectly contribute to HDCA‐suppressed cell proliferation. Together, HDCA suppressed intestinal epithelial cell proliferation through FXR‐PI3K/AKT signaling pathway, accompanied by alteration of BAs metabolism profiles induced by gut bacteria.