NAT10-mediated ac4C modification promotes ectoderm differentiation of human embryonic stem cells via acetylating NR2F1 mRNA.

Cell fate determination in mammalian development is complex and precisely controlled and accumulating evidence indicates that epigenetic mechanisms are crucially involved. N4-acetylcytidine (ac4C) is a recently identified modification of messenger RNA (mRNA); however, its functions are still elusive in mammalian. Here, we show that N-acetyltransferase 10 (NAT10)-mediated ac4C modification promotes ectoderm differentiation of human embryonic stem cells (hESCs) by acetylating nuclear receptor subfamily 2 group F member 1 (NR2F1) mRNA to enhance translation efficiency (TE). Acetylated RNA immunoprecipitation sequencing (acRIP-seq) revealed that levels of ac4C modification were higher in ectodermal neuroepithelial progenitor (NEP) cells than in hESCs or mesoendoderm cells. In addition, integrated analysis of acRIP-seq and ribosome profiling sequencing revealed that NAT10 catalysed ac4C modification to improve TE in NEP cells. RIP-qRT-PCR analysis identified an interaction between NAT10 and NR2F1 mRNA in NEP cells and NR2F1 accelerated the nucleus-to-cytoplasm translocation of yes-associated protein 1, which contributed to ectodermal differentiation of hESCs. Collectively, these findings point out the novel regulatory role of ac4C modification in the early ectodermal differentiation of hESCs and will provide a new strategy for the treatment of neuroectodermal defects diseases.

Effect of FSH on E2/GPR30-mediated mouse oocyte maturation in vitro.

Mammalian oocyte restores meiosis can be stimulated by follicle-stimulating hormone (FSH) under normal physiological conditions. G-protein coupled receptor 30 (GPR30), an non-classical estrogen membrane receptor, has been widely reported in teleost oocyte maturation. However, it remains unknown whether GPR30 involves the role of FSH in mammalian cumulus expansion and oocyte maturation. Here, we used mouse cumulus-oocyte complexes (COCs) as a model to investigate how FSH affects the in vitro maturation of mouse oocytes mediated by 17ß-estradiol (E2)/GPR30signaling. Our study reveals that FSH starts regulating mouse cumulus expansion precisely at 8h in in vitro culture. ELISA measurement of E2 levels in culture medium revealed that FSH activated aromatase to promote E2 production in vitro in cultured mouse COCs. Moreover, the results of real-time quantitative PCR indicated that FSH-induced in vitro maturation of mouse oocytes was regulated by the estrogen-signaling pathway mediated by GPR30; FSH treatment markedly increased the mRNA expression of HAS2, PTGS2, and GREM1 in COCs. Exploration of the underlying mechanism suggested that E2 produced by mouse COCs regulated the phosphorylation level of extracellular signal-regulated kinase 1/2 (ERK1/2) through GPR30 and thereby promoted mouse cumulus-cell expansion and oocyte maturation. In conclusion, our study reveals that FSH induced estrogen production in mouse COCs through aromatase, and that aromatase/GPR30/ERK1/2 signaling is involved in FSH-induced cumulus expansion.

Role of endoplasmic reticulum stress in lipopolysaccharide-inhibited mouse granulosa cell estradiol production.

The decrease in the level of estradiol (E2) in granulosa cells caused by lipopolysaccharide (LPS) is one of the major causes of infertility underlying postpartum uterine infections; the precise molecular mechanism of which remains elusive. This study investigated the role of endoplasmic reticulum (ER) stress in LPS-induced E2 decrease in mouse granulosa cells. Our results showed that LPS increased the pro-inflammatory cytokines [(interleukin (IL)-1ß, IL-6, IL-8, and tumor necrosis factor (TNF)-α)], activated ER stress marker protein expression [(glucose-regulated protein 78 (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP)], and decreased cytochrome P450 family 19 subfamily A member 1 (Cyp19a1) expression and E2 production. Moreover, inhibition of ER stress by 4-phenylbutyrate (4-PBA) attenuated thapsigargin-(TG, ER stress agonist) or LPS-induced reduction of Cyp19a1 and E2, pro-inflammatory cytokines expression (IL-1ß, IL-6, IL-8, and TNF-α), and the expression of CHOP and GRP78. Additionally, inhibition of toll-like receptor 4 (TLR4) by resatorvid (TAK-242) reversed the inhibitory effects of LPS on Cyp19a1 expression and E2 production, activation of GRP78 and CHOP, and expression of IL-1ß, IL-6, IL-8, and TNF-α. In summary, our study suggests that ER stress is involved in LPS-inhibited E2 production in mouse granulosa cells.

6-Bromoindirubin-3'-oxime promotes osteogenic differentiation of canine BMSCs through inhibition of GSK3ß activity and activation of the Wnt/ß-catenin signaling pathway.

This study aimed to investigate how 6-bromoindirubin-3'-oxime (BIO) increases the osteogenic differentiation of canine bone mesenchymal stem cells (BMSCs) and the role of the Wnt/ß-catenin signaling pathway in this process. We mimicked the effect of Wnt by adding BIO to the culture medium of BMSCs and examined whether canonical Wnt signaling positively affects the differentiation of these cells into osteoblasts. Canine BMSCs were cultured with 0.5 and 1.0 µM BIO under osteogenic conditions and then differentiation markers were investigated. It was found that BIO significantly increased the activity of alkaline phosphatase (ALP), the number of ALP-positive cells, the mineralization level and calcium deposits. Moreover, cells cultured with 0.5 and 1.0 µM BIO exhibited detectable ß-catenin expression in their nuclei, and showed upregulated ß-catenin and glycogen synthase kinase 3 beta(GSK3ß) phosphorylation compared to untreated cells. In addition, BIO enhanced the mRNA expression of osteoblast differentiation markers such as ALP, runt-related transcription factor 2, collagen I, osteocalcin, and osteonectin. In conclusion, BIO upregulated GSK3ß phosphorylation and inhibited its activity, thereby activating the Wnt/ß-catenin signaling pathway and promoting the osteogenic differentiation of canine BMSCs. The effect of 1.0 µM BIO on BMSCs differentiation was stronger than that of 0.5 µM BIO.

C-type natriuretic peptide improved vitrified-warmed mouse cumulus oocyte complexes developmental competence.

Cryopreservation of cumulus oocyte complexes (COCs) is important for reproductive medicine. However, the vitrified-warmed COCs have lower maturation rate and subsequent developmental competence compared with fresh COCs. The present study was aimed to evaluate the effects of supplementation of the maturation medium with C-type natriuretic peptide (CNP) on the developmental competence of vitrified-warmed mouse COCs. Addition of CNP to the maturation medium improved the maturation rate and enhanced the developmental competence of vitrified-warmed mouse COCs. The reason may be that vitrified COCs led to a decline in cyclic guanosine monophosphate (cGMP) levels. Furthermore, addition of CNP to the maturation medium elevated cGMP levels of the vitrified-warmed COCs. In conclusion, cryopreservation-associated lower maturation rate and developmental competence of COCs may be ameliorated by CNP during maturation culture after warming.

MAPK3/1 is conducive to luteinizing hormone-mediated C-type natriuretic peptide decrease in bovine granulosa cells.

C-type natriuretic peptide (CNP) plays a role as an oocyte maturation inhibitor (OMI) in many species, including the bovine. However, the effects of luteinizing hormone (LH) on CNP expression and its potential mechanisms have not reported in the bovine. In the present study, we aimed to study the effects of LH on CNP expression and to illuminate the potential molecular mechanism in this process. Our results showed that LH induced epidermal growth factor receptor (EGFR) phosphorylation, mitogen-activated protein kinase3/1 (MAPK3/1) activation and CNP mRNA decrease in cultured bovine granulosa cells. Further study revealed that LH suppressed CNP expression via the MAPK3/1 signaling pathway, which was activated by the EGFR pathway. In conclusion, our research suggested that MAPK3/1 is involved in LH-mediated decrease of CNP and that this process is related to the EGFR and MAPK3/1 signal pathways.