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Weiwei Qin, Wenbao Lu, Hongwei Li, Xiaochen Yuan, Bingwei Li, Qiuju Zhang and Ruijuan Xiu

Matrix metalloproteinases (MMPs) have been involved in inflammatory and degradative processes in pathologic conditions. The purpose of this study was to investigate the protective effect of melatonin in human umbilical vein endothelial cell (HUVEC) monolayer permeability and the regulation of MMP9 induced by interleukin 1β (IL1β (IL1B)) in HUVECs. Protection studies were carried out with melatonin, a well-known antioxidant and antiinflammatory molecule. MMP9 expression was increased with IL1β induction in HUVECs. Melatonin showed a barrier-protective role by downregulation of MMP9 and upregulation of tissue inhibitor of metalloproteinase-1 expression in HUVECs. Meanwhile, melatonin also decreased sodium fluorescein permeability and counteracted the downregulation of vascular endothelial cadherin and occludin expression in HUVECs. During inflammatory stimulus, nuclear factor-κB (NF-κB) plays a significant role in regulating MMP genes expression, thus the function of NF-κB in HUVECs' barrier disruption was investigated. IL1β induced nuclear translocation of NF-κB in HUVECs and regulated MMP9 expression. However, NF-κB translocation into the nucleus was inhibited significantly by melatonin. Our results show that melatonin decreases the permeability of monolayer endothelial cell induced by IL1β. At the same time, melatonin decreased the expression and activity of MMP9 by a NF-κB-dependent pathway in HUVECs induced by IL1β.

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Yuxun Zhou, Li Tong, Maochun Wang, Xueying Chang, Sijia Wang, Kai Li and Junhua Xiao

Puberty onset is a complex trait regulated by multiple genetic and environmental factors. In this study, we narrowed a puberty-related QTL region down to a 1.7 Mb region on chromosome X in female mice and inferred miR-505-3p as the functional gene. We conducted ectopic expression of miR-505-3p in the hypothalamus of prepubertal female mice through lentivirus-mediated orthotopic injection. The impact of miR-505-3p on female puberty was evaluated by the measurement of pubertal/reproduction events and histological analysis. The results showed that female mice with overexpression of miR-505-3p in the hypothalamus manifested later puberty onset timing both in vaginal opening and ovary maturation, followed by weaker fertility lying in the longer interval time between mating and delivery, higher abortion rate and smaller litter size. We also constructed miR-505-3p-knockout mice by CRISPR/Cas9 technology. miR-505-3p-knockout female mice showed earlier vaginal opening timing, higher serum gonadotrophin and higher expression of puberty-related gene in the hypothalamus than their WT littermates. Srsf1 proved to be the target gene of miR-505-3p that played the major role in this process. The results of RNA immunoprecipitation sequencing showed that SRSF1 (or SF2), the protein product of Srsf1 gene, mainly bound to ribosome protein (RP) mRNAs in GT1-7 cells. The collective evidence implied that miR-505-3p/SRSF1/RP could play a role in the sexual maturation regulation of mammals.

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Shan-Jin Wang, Xin-Feng Li, Lei-Sheng Jiang and Li-Yang Dai

Regulation of the physiological processes of endochondral bone formation during long bone growth is controlled by various factors including the hormones estrogen and leptin. The effects of estrogen are mediated not only through the direct activity of estrogen receptors (ERs) but also through cross talk with other signaling systems implicated in chondrogenesis. The receptors of both estrogen and leptin (OBR (LEPR)) are detectable in growth plate chondrocytes of all zones. In this study, the expression of mRNA and protein of OBR in chondrogenic ATDC5 cells and the effect of 17β-estradiol (E2) stimulation were assessed using quantitative PCR and western blotting. We have found that the mRNA of Obr was dynamically expressed during the differentiation of ATDC5 cells over 21 days. Application of E2 (10−7 M) at day 14 for 48 h significantly upregulated OBR mRNA and protein levels (P<0.05). The upregulation of Obr mRNA by E2 was shown to take place in a concentration-dependent manner, with a concentration of 10−7 M E2 having the greatest effect. Furthermore, we have confirmed that E2 affected the phosphorylation of ERK1/2 (MAPK1/MAPK3) in a time-dependent manner where a maximal fourfold change was observed at 10 min following application of E2. Finally, pretreatment of the cells with either U0126 (ERK1/2 inhibitor) or ICI 182 780 (ER antagonist) blocked the upregulation of OBR by E2 and prevented the E2-induced phosphorylation of ERK. These data demonstrate, for the first time, the existence of cross talk between estrogen and OBR in the regulation of bone growth whereby estrogen regulates the expression of Obr in growth plate chondrocytes via ERs and the activation of ERK1/2 signaling pathways.

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Li Zhang, XiaoXin Zhang, Xuejing Zhang, Yu Lu, Lei Li and Sheng Cui

MicroRNAs (MiRNAs) play important regulatory roles in many cellular processes. MiR-143 is highly enriched in the mouse ovary, but its roles and underlying mechanisms are not well understood. In the current study, we show that miR-143 is located in granulosa cells of primary, secondary and antral follicles. To explore the specific functions of miR-143, we transfected miR-143 inhibitor into primary cultured granulosa cells to study the loss of function of miR-143 and the results showed that miR-143 silencing significantly increased estradiol production and steroidogenesis-related gene expression. Moreover, our in vivo and in vitro studies showed that follicular stimulating hormone (FSH) significantly decreased miR-143 expression. This function of miR-143 is accomplished by its binding to the 3’-UTR of KRAS mRNA. Furthermore, our results demonstrated that miR-143 acts as a negative regulating molecule mediating the signaling pathway of FSH and affecting estradiol production by targeting KRAS. MiR-143 also negatively acts in regulating granulosa cells proliferation and cell cycle-related genes expression. These findings indicate that miR-143 plays vital roles in FSH-induced estradiol production and granulosa cell proliferation, providing a novel mechanism that involves miRNA in regulating granulosa cell functions.

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Guoyue Yuan, Xia Chen, Qinyun Ma, Jie Qiao, Rongying Li, Xuesong Li, Shengxian Li, Jinfeng Tang, Libin Zhou, Huaidong Song and Mingdao Chen

C-reactive protein (CRP) is considered as one of the most sensitive markers of inflammation. The aim of the present study is to investigate the effects of CRP on the production of adiponectin in 3T3-L1 adipocytes. Northern and western blot analysis revealed that CRP treatment inhibited adiponectin mRNA expression and secretion in a dose- and time-dependent manner. Co-incubation of adipocytes with rosiglitazone and CRP decreased induction of adiponectin gene expression by rosiglitazone. However, luciferase reporter assays did not show that CRP affected the activity of ~2.1 kb adiponectin gene promoter, which was increased by rosiglitazone alone. Pharmacological inhibition of phosphatidylinositol (PI)-3 kinase by LY294002 partially reversed inhibition of adiponectin gene expression by CRP. These results collectively suggest that CRP suppresses adiponectin gene expression partially through the PI-3 kinase pathway, and that decreased production of adiponectin might represent a mechanism by which CRP regulates insulin sensitivity.

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Shiyun Tong, Shumin Yang, Ting Li, Rufei Gao, Jinbo Hu, Ting Luo, Hua Qing, Qianna Zhen, Renzhi Hu, Xuan Li, Yi Yang, Chuan Peng and Qifu Li

Bisphenol-A (BPA) is a common environmental pollutant, and exposure to it is associated with proteinuria and may predict the progression of chronic kidney disease; however, the mechanism is not clear. Neutrophil extracellular traps (NETs) are a DNA skeleton coated with various proteases, and it is associated with various types of autoimmune nephritis. In this study, we examine whether NETs is involved in BPA-induced chronic kidney injury. In vivo, BPA exposure resulted in impaired renal function and altered renal morphology, including glomerular mesangial matrix expansion and increased renal interstitial fibroblast markers. Meanwhile, more dsDNA can be detected in the serum, and the NETs-associated proteins, MPO and citH3 were deposited in the renal system. In vitro, BPA and NETs treatment caused podocyte injury, a loss of marker proteins and disorder in the actin skeleton. After NETs inhibition via DNase administration, BPA-induced injuries were significantly relieved. In conclusion, the increase of NETosis in circulation and the renal system during BPA exposure suggests that NETs may be involved in BPA-induced chronic kidney injury.

Free access

Can Liu, Mian Zhang, Meng-yue Hu, Hai-fang Guo, Jia Li, Yun-li Yu, Shi Jin, Xin-ting Wang, Li Liu and Xiao-dong Liu

Panax ginseng is one of the most popular herbal remedies. Ginsenosides, major bioactive constituents in P. ginseng, have shown good antidiabetic action, but the precise mechanism was not fully understood. Glucagon-like peptide-1 (GLP1) is considered to be an important incretin that can regulate glucose homeostasis in the gastrointestinal tract after meals. The aim of this study was to investigate whether ginseng total saponins (GTS) exerts its antidiabetic effects via modulating GLP1 release. Ginsenoside Rb1 (Rb1), the most abundant constituent in GTS, was selected to further explore the underlying mechanisms in cultured NCI-H716 cells. Diabetic rats were developed by a combination of high-fat diet and low-dose streptozotocin injection. The diabetic rats orally received GTS (150 or 300 mg/kg) daily for 4 weeks. It was found that GTS treatment significantly ameliorated hyperglycemia and dyslipidemia, accompanied by a significant increase in glucose-induced GLP1 secretion and upregulation of proglucagon gene expression. Data from NCI-H716 cells showed that both GTS and Rb1 promoted GLP1 secretion. It was observed that Rb1 increased the ratio of intracellular ATP to ADP concentration and intracellular Ca2 + concentration. The metabolic inhibitor azide (3 mM), the KATP channel opener diazoxide (340 μM), and the Ca2 + channel blocker nifedipine (20 μM) significantly reversed Rb1-mediated GLP1 secretion. All these results drew a conclusion that ginsenosides stimulated GLP1 secretion both in vivo and in vitro. The antidiabetic effects of ginsenosides may be a result of enhanced GLP1 secretion.

Open access

Ya-Li Yang, Li-Rong Ren, Li-Feng Sun, Chen Huang, Tian-Xia Xiao, Bao-Bei Wang, Jie Chen, Brian A Zabel, Peigen Ren and Jian V Zhang

Chemerin, a chemokine, plays important roles in immune responses, inflammation, adipogenesis, and carbohydrate metabolism. Our recent research has shown that chemerin has an inhibitory effect on hormone secretion from the testis and ovary. However, whether G protein-coupled receptor 1 (GPR1), the active receptor for chemerin, regulates steroidogenesis and luteolysis in the corpus luteum is still unknown. In this study, we established a pregnant mare serum gonadotropin-human chorionic gonadotropin (PMSG-hCG) superovulation model, a prostaglandin F2α (PGF2α) luteolysis model, and follicle and corpus luteum culture models to analyze the role of chemerin signaling through GPR1 in the synthesis and secretion of gonadal hormones during follicular/luteal development and luteolysis. Our results, for the first time, show that chemerin and GPR1 are both differentially expressed in the ovary over the course of the estrous cycle, with highest levels in estrus and metestrus. GPR1 has been localized to granulosa cells, cumulus cells, and the corpus luteum by immunohistochemistry (IHC). In vitro, we found that chemerin suppresses hCG-induced progesterone production in cultured follicle and corpus luteum and that this effect is attenuated significantly by anti-GPR1 MAB treatment. Furthermore, when the phosphoinositide 3-kinase (PI3K) pathway was blocked, the attenuating effect of GPR1 MAB was abrogated. Interestingly, PGF2α induces luteolysis through activation of caspase-3, leading to a reduction in progesterone secretion. Treatment with GPR1 MAB blocked the PGF2α effect on caspase-3 expression and progesterone secretion. This study indicates that chemerin/GPR1 signaling directly or indirectly regulates progesterone synthesis and secretion during the processes of follicular development, corpus luteum formation, and PGF2α-induced luteolysis.

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Min Liu, Shuo Xie, Weiwei Liu, Jingjin Li, Chao Li, Wei Huang, Hexin Li, Jinghai Song and Hong Zhang

Obesity is a worldwide health problem. Semaphorins are involved in axonal guidance; however, the role of secretory semaphorin 3G (SEMA3G) in regulating adipocyte differentiation remains unclear. Microarray analysis showed that the SEMA3G gene was upregulated in an in vitro model of adipogenesis. In this study, SEMA3G was highly expressed in the white adipose tissue and liver. Analysis of 3T3-L1 cell and primary mouse preadipocyte differentiation showed that SEMA3G mRNA and protein levels were increased during the middle stage of cell development. In vitro experiments also showed that adipocyte differentiation was promoted by SEMA3G; however, SEMA3G inhibition using a recombinant lentiviral vector expressing a specific shRNA showed the opposite results. Mice were fed a chow or high-fat diet (HFD); knockdown of SEMA3G was found to inhibit weight gain, reduce fat mass in the tissues, prevent lipogenesis in the liver tissue, reduce insulin resistance and ameliorate glucose tolerance in HFD mice. Additionally, the effect of SEMA3G on HFD-induced obesity was activated through PI3K/Akt/GSK3β signaling in the adipose tissue and the AMPK/SREBP-1c pathway in the liver. Moreover, the plasma concentrations of SEMA3G and leptin were measured in 20 obese and 20 non-obese human subjects. Both proteins were increased in obese subjects, who also exhibited a lower level of adiponectin and presented with insulin resistance. In summary, we demonstrated that SEMA3G is an adipokine essential for adipogenesis, lipogenesis, and insulin resistance and is associated with obesity. SEMA3G inhibition may, therefore, be useful for treating diet-induced obesity and its complications.

Free access

Xiaoqin Shi, Xinyu Li, Yi Hou, Xuemei Cao, Yuyao Zhang, Heng Wang, Hongyin Wang, Chuan Peng, Jibin Li, Qifu Li, Chaodong Wu and Xiaoqiu Xiao

Parental history with obesity or diabetes will increase the risk for developing metabolic diseases in offspring. However, literatures as to transgenerational inheritance of metabolic dysfunctions through male lineage are relatively scarce. In the current study, we aimed to evaluate influences of paternal hyperglycemia on metabolic phenotypes in offspring. Male SD rats were i.p. injected with streptozotocin (STZ) or citrate buffer (CB, as control). STZ-injected rats with glucose levels higher than 16.7 mM were selected to breed with normal female rats. Offspring from STZ or CB treated fathers (STZ-O and CB-O) were maintained in the identical condition. We monitored body weight and food intake, and tests of glucose and insulin tolerance (GTTs and ITTs), fasting–refeeding and cold exposure were performed. Expression of factors involved in hypothalamic feeding and brown adipose tissue (BAT) thermogenic activity was performed by real-time PCR and Western blot. Adult STZ-O were heavier than CB-O. Impairment of GTTs was observed in STZ-O compared with CB-O at 22 and 32 weeks of age; ITTs results showed decreased insulin sensitivity in STZ-O. Daily food intake and accumulated food intake during 12-h refeeding after fasting were significantly higher in STZ-O. UCP1 levels were downregulated in BAT from STZ-O at room temperature and cold exposure. Finally, STZ-O rats showed suppressed leptin signaling in the hypothalamus as evidenced by upregulated SOCS3, reduced phosphorylation of STAT3, impaired processing POMC and decreased α-MSH production. Our study revealed that paternal hyperglycemia predisposes offspring to developing obesity, which is possibly associated with impaired hypothalamic leptin signaling.