Search

Spermatogonial stem cells (SSCs) are adult stem cells in the testis of male animals and have the ability in self-renewal and differentiation. SSCs are derived from primordial germ cells (PGCs) that are mitotically arrested in the embryo before birth. Following the birth of the animal, PGCs resume mitosis and migrate from the centre of the seminiferous tubules to the basement membrane. The descendent of PGCs (also called gonocytes) establish stable SSC colonies in about a week postnatally in order to support the life-long spermatogenesis. Whether SSCs at different developmental stages differ in their molecular and cellular characteristics is currently unclear. In the presented study, we conducted bioinformatics analyses using transcriptomics data established previously in the laboratory on OCT4 (encoded by the pluripotent gene Pou5f1) expressing SSCs from the neonatal (3 days-post-partum, 3-dpp), juvenile (7-dpp) and adult (2~3-month) mice, including screen of differentially expressed genes (DEGs), protein-protein interaction (PPI) network analysis of DEGs and clustering of sub-networks from PPI. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses were also performed on clustered sub-networks of the PPI. In addition, all genes were analyzed using GSEA (gene set enrichment analysis) based on GO, KEGG and HALLMARK gene sets. The results showed that SSCs have a large number of DEGs among OCT4-positive SSCs from neonatal, juvenile and adult mice. The distinguishable biological functions encoded by these DEGs include biosynthesis and energy metabolism, immune response, cell junction and expression of migration and cell differentiation-related genes. Significant changes in the cell membrane composition of OCT4-positive SSCs may not only cause hypersensitive immune reactions but also affect the cell-cell contact and responses to secreted cytokines in the extracellular environment. The results also suggest that OCT4-positive SSCs may shift metabolic state from oxidative phosphorylation to glycolysis and significantly reduce the transcription of genes related to ribosome formation during aging. These results provide new clues for future research on the regulatory mechanisms of male germline stem cell development, growth and aging.精原干细胞(spermatogonial stem cells, SSCs)是成年动物睾丸中的成体干细胞,具有自我更新与分化的能力。小鼠(Mus musculus)精原干细胞来源于胚胎期的原始生殖细胞(primodial germ cells, PGCs),小鼠出生前原始生殖细胞处于有丝分裂静止状态,出生后恢复增殖并由曲细精管中央迁移至管壁基质,建立稳定的精原干细胞克隆。成熟小鼠的精原干细胞周期性地启动精子发生以维持雄性动物长期稳定的生殖能力。精原干细胞在其建立和成熟后是否具有特征上的差异目前尚不清楚。本研究在前期建立的不同年龄小鼠精原干细胞(表达多能性基因Pou5f1编码的OCT4)转录组数据基础上,对小鼠新生期(出生后3天)、幼年期(出生后7天)和成熟期(2~3月龄)精原干细胞的基因表达差异进行了生物信息学分析,包括差异表达基因(differentially expression genes, DEGs)的筛选、DEGs编码的蛋白相互作用网络(protein-protein interaction, PPI)的建立、功能聚类富集(Gene Ontology, GO)和通路分析(Kyoto Encyclopedia of Genes and Genomes, KEGG),以及使用基于GO、KEGG和HALLMARK的基因集富集分析(gene set enrichment analysis, GSEA)。结果显示,OCT4阳性精原干细胞在小鼠新生期、幼年期和成熟期存在大量差异表达基因,所编码的蛋白主要生物学功能集中在生物合成和能量代谢、免疫反应、细胞连接和迁移以及细胞分化等方面。精原干细胞细胞膜成分的显著变化可能影响精原干细胞的超敏反应、细胞间相互作用以及对细胞外环境因子的应答反应。在能量代谢方式上,随着年龄的增加,OCT4阳性精原干细胞逐渐从线粒体氧化磷酸化作用转变为糖酵解作用,同时也显著减少了细胞内核糖体形成相关基因的转录。这些结果为进一步研究雄性生殖干细胞形成和成熟的调控机制提供了新的思路。.

Ginsenosides regulate glucose homeostasis. This study investigated the effect of ginsenoside Rg5 (Rg5) on the hepatic glucagon response, focusing on the regulation of metabolism. Mice fed a high-fat diet (HFD) showed increased hepatic glucose production (HGP). We observed the effects of Rg5 on hepatic fatty acid oxidation and glucagon response. The regulation of phosphodiesterase (PDE) 4B by succinate was also investigated in hepatocytes. Rg5 inhibited endogenous glucose production in HFD-fed mice. Rg5 reduced cyclic AMP (cAMP) accumulation and inhibited transcriptional regulation of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) by dephosphorylation of the cAMP response element-binding transcription factor in the liver, demonstrating the inhibitory effect on hepatic glucagon response. HFD feeding increased succinate accumulation in the liver due to the reversal of succinate dehydrogenase activation and triggered hypoxia-inducible factor-1α (HIF-1α) induction. Succinate prevented cAMP degradation by inactivating PDE4B, thereby increasing cAMP accumulation in response to glucagon. Knockdown of HIF-1α with small interfering RNA diminished the effect of succinate, indicating that HIF-1α was essential for succinate to inactivate PDE4B. Rg5 inhibited succinate accumulation in hepatocytes by combating fatty acid oxidation, and thus reduced cAMP accumulation by blocking succinate/HIF-1α induction. Rg5 reduced HGP as a consequence of the inhibition of the glucagon response. Succinate acted as a metabolic signal to enhance the hepatic glucagon response. Rg5 reduced hepatic succinate accumulation by combating fatty acid oxidation and attenuated the hepatic glucagon response by suppressing succinate/HIF-1α induction, suggesting that succinate-associated HIF-1α induction in hepatocytes might be a therapeutic target in the treatment of diabetes.

Quercetin is a natural flavonoid widely distributed in human diet and functional foods. Quercetin 3-O-β-glucuronide (Q3G) is present in wine and some medicinal plants. Quercetin and Q3G may be metabolized from each other in vivo. While quercetin has been the subject of many studies, the pharmacokinetic profiles of quercetin and Q3G (in animals) have not yet been compared. Herein, we prepared a column-based method for rapid isolation of Q3G from Nelumbo nucifera. Then, we developed an UHPLC-MS/MS method to compare the pharmacokinetics of quercetin and Q3G. Our results showed that the plasma concentration-time curves of quercetin and Q3G show two maxima (Tmax1 ≈ 0.75 h, Tmax2 ≈ 5 h). After oral administration of 100 mg/kg quercetin or 100 mg/kg Q3G in rats, predominantly Q3G was detected in plasma with AUC at 39529.2 ± 6108.2 mg·h·L−1 or 24625.1 ± 1563.8 mg·h·L−1, 18-fold higher than quercetin with AUC at 1583.9 ± 583.3 mg·h·L−1 or 1394.6 ± 868.1 mg·h·L−1, respectively. After intravenous injection of 10 mg/kg in rats, Q3G showed extensive tissue uptake in kidney (409.2 ± 118.4 ng/g), liver (166.1 ± 52.9 ng/g), heart (97.7 ± 22.6 ng/g), and brain (5.8 ± 1.2 ng/g). In conclusion, we have shown that Q3G is a major active component in plasma and tissue for oral administration of quercetin or Q3G.

cope Quercetin is a dietary flavonoid whose role in the regulation of the activity of insulin remains controversial. Our study aimed to investigate how quercetin and its major metabolite quercetin-3-glucuronide (Q-3-G) regulate insulin-mediated glucose disposal in skeletal muscle under normal and inflammatory conditions. Methods and results Under normal conditions, quercetin impaired glucose and insulin tolerance and attenuated insulin-mediated phosphorylation of Akt substrate of 160 kDa (AS160) and TBC1D1 without affecting Akt activity in male Institute of Cancer Research (ICR) mice. However, under inflammatory conditions, quercetin exhibited an opposite effect in these animals. In C2C12 cells, quercetin also decreased insulin-stimulated AS160 and TBC1D1 phosphorylation and glucose uptake in the absence of an inflammatory insult, whereas it improved the action of insulin under inflammatory conditions. Knockdown of adenosine 5′-monophosphate-activated protein kinase α (AMPKα) blocked the differential effects of quercetin under both conditions. Unlike quercetin, Q-3-G had no influence on insulin-induced phosphorylation of AS160 and TBC1D1 and glucose uptake in C2C12 myotubes under normal conditions. Q-3-G displayed a similar regulation with quercetin in glucose disposal under inflammatory conditions. Conclusion Quercetin suppressed insulin-mediated glucose disposal in skeletal muscle tissue/cells under normal conditions while it ameliorated impaired glucose uptake under inflammatory conditions with activation of AMPK. In contrast, Q-3-G ameliorated insulin resistance in skeletal cells under inflammatory conditions without affecting glucose disposal under normal conditions.