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Lijuan Yin, Fang Fang, Xinglei Song, Yan Wang, Gaoxiang Huang, Jie Su, Ning Hui, and Jian Lu

Cell adhesion to extracellular matrix (ECM) is controlled by multiple signaling molecules and intracellular pathways, and is pivotal for survival and growth of cells from most solid tumors. Our previous works demonstrated that dexamethasone (DEX) significantly enhances cell adhesion and cell resistance to chemotherapeutics by increasing the levels of integrin β1, α4, and α5 in human ovarian cancer cells. However, it is unclear whether the components of ECM or other membrane molecules are also involved in the pro-adhesive effect of DEX in ovarian cancer cells. In this study, we demonstrated that the treatment of cells with DEX did not change the expression of collagens (I, III, and IV), laminin, CD44, and its principal ligand hyaluronan (HA), but significantly increased the levels of intracellular and secreted fibronectin (FN). Inhibiting the expression of FN with FN1 siRNA or blocking CD44, another FN receptor, with CD44 blocking antibody significantly attenuated the pro-adhesion of DEX, indicating that upregulation of FN mediates the pro-adhesive effect of DEX by its interaction with CD44 besides integrin β1. Moreover, DEX significantly enhanced cell resistance to the chemotherapeutic agent paclitaxel (PTX) by activating PI-3K-Akt pathway. Finally, we found that DEX also significantly upregulated the expression of MUC1, a transmembrane glycoprotein. Inhibiting the expression of MUC1 with MUC1 siRNA significantly attenuated the DEX-induced effects of pro-adhesion, Akt-activation, and pro-survival. In conclusion, these results provide new data that upregulation of FN and MUC1 by DEX contributes to DEX-induced pro-adhesion and protects ovarian cancer cells from chemotherapy.

Open access

Bo Li, Zhiguo Zhang, Huizhi Zhang, Kai Quan, Yan Lu, Dongsheng Cai, and Guang Ning

The prevalence of non-alcoholic fatty liver disease (NAFLD), a condition characterized by an excessive accumulation of triglycerides (TGs) in hepatocytes, has dramatically increased globally during recent decades. MicroRNAs (miRs) have been suggested to play crucial roles in many complex diseases and lipid metabolism. Our results indicated that miR199a-5p was remarkably upregulated in free fatty acid (FA)-treated hepatocytes. To investigate the role of miR199a-5p in the pathogenesis of fatty liver and the potential mechanism by which miR199a-5p regulates NAFLD, we first transfected two hepatocyte cell lines, HepG2 and AML12 cells, with agomiR199a-5p or antagomiR199a-5p. Our results indicated that miR199a-5p overexpression exacerbated deposition of FA and inhibited ATP levels and mitochondrial DNA (mtDNA) contents. Consistently, suppression of miR199a-5p partially alleviated deposition of FA and increased ATP levels and mtDNA contents. Moreover, miR199a-5p suppressed the expression of mitochondrial FA β-oxidation-related genes through inhibition of caveolin1 (CAV1) and the related peroxisome proliferator-activated receptor alpha (PPAR α) pathway. Furthermore, suppression of CAV1 gene expression by CAV1 siRNA inhibited the PPARα signalling pathway. Finally, we examined the expression of miR199a-5p in liver samples derived from mice fed a high-fat diet, db/db mice, ob/ob mice and NAFLD patients, and found that miR199a-5p was upregulated while CAV1 and PPARA were downregulated in these systems, which was strongly indicative of the essential role of miR199a-5p in NAFLD. In summary, miR199a-5p plays a vital role in lipid metabolism, mitochondrial activity and mitochondrial β-oxidation in liver. Upregulated miR199a-5p in hepatocytes may contribute to impaired FA β-oxidation in mitochondria and aberrant lipid deposits, probably via CAV1 and the PPARα pathway.

Free access

Qianqian Lu, Yuying Yang, Sheng Jia, Shaoqiang Zhao, Bin Gu, Peng Lu, Yang He, Ruixin Liu, Jiqiu Wang, Guang Ning, and Qinyun Ma

Appetite is tightly controlled by neural and hormonal signals in animals. In general, steroid receptor coactivator 1 (SRC1) enhances steroid hormone signalling in energy balance and serves as a common coactivator of several steroid receptors, such as oestrogen and glucocorticoid receptors. However, the key roles of SRC1 in energy balance remain largely unknown. We first confirmed that SRC1 is abundantly expressed in the hypothalamic arcuate nucleus (ARC), which is a critical centre for regulating feeding and energy balance; it is further co-localised with agouti-related protein and proopiomelanocortin neurons in the arcuate nucleus. Interestingly, local SRC1 expression changes with the transition between sufficiency and deficiency of food supply. To identify its direct role in appetite regulation, we repressed SRC1 expression in the hypothalamic ARC using lentivirus shRNA and found that SRC1 deficiency significantly promoted food intake and body weight gain, particularly in mice fed with a high-fat diet. We also found the activation of the AMP-activated protein kinase (AMPK) signalling pathway due to SRC1 deficiency. Thus, our results suggest that SRC1 in the ARC regulates appetite and body weight and that AMPK signalling is involved in this process. We believe that our study results have important implications for recognising the overlapping and integrating effects of several steroid hormones/receptors on accurate appetite regulation in future studies.

Free access

Qianqian Lu, Yuying Yang, Sheng Jia, Shaoqian Zhao, Bin Gu, Peng Lu, Yang He, Ruixin Liu, Jiqiu Wang, Guang Ning, and Qinyun Ma

Free access

Guojun Shi, Chen Sun, Weiqiong Gu, Minglan Yang, Xiaofang Zhang, Nan Zhai, Yan Lu, Zhijian Zhang, Peishun Shou, Zhiguo Zhang, and Guang Ning

Recent reports have highlighted the roles of free fatty acid receptor 2 (FFAR2) in the regulation of metabolic and inflammatory processes. However, the potential function of FFAR2 in type 1 diabetes (T1D) remains unexplored. Our results indicated that the mRNA level of FFAR2 was upregulated in peripheral blood mononuclear cells of T1D patients. The human FFAR2 promoter regions were cloned, and luciferase reporter assays revealed that NFκB activation induced FFAR2 expression. Furthermore, we showed that FFAR2 activation by overexpression induced cell apoptosis through ERK signaling. Finally, treatment with the FFAR2 agonists acetate or phenylacetamide 1 attenuated the inflammatory response in multiple-low-dose streptozocin-induced diabetic mice, and improved the impaired glucose tolerance. These results indicate that FFAR2 may play a protective role by inducing apoptosis of infiltrated macrophage in the pancreas through its feedback upregulation and activation, thus, in turn, improving glucose homeostasis in diabetic mice. These findings highlight FFAR2 as a potential therapeutic target of T1D, representing a link between immune response and glucose homeostasis.

Free access

Longfei Xiao, Zihui Wang, Ning Lu, Yanan He, Limin Qiao, Xihui Sheng, Xiaolong Qi, Kai Xing, Yong Guo, Di Chang, Xiangguo Wang, Junjin Zhao, Xiaobin Deng, Hemin Ni, and Jian Kang

Vascular endothelial growth factor (VEGF) plays a pivotal role in angiogenesis in ovaries, particularly during follicular development and ovulation. Interleukin-6 (IL-6) is one of the major pro-inflammatory factors that are involved in the angiogenesis process physiologically and pathologically. Previous studies have shown that 17β-estradiol (E2) stimulates VEGF expression by upregulating hypoxia-inducible factor 1α (HIF-1α) in many cell types, and the high level of E2 causes an inflammatory-like microenvironment before ovulation. However, whether IL-6 signaling is involved in E2-regulating VEGF expression in swine granulosa cells (GCs) is still unknown. In this study, we found the estrogen membrane receptor, G-protein-coupled estrogen receptor 1 (GPER), was expressed in swine GCs, and the expression level of GPER, HIF-1α, and VEGF increased with follicular development. In vitro study showed that E2, ICI182780, and GPER agonist (G1) promoted the expressions of HIF-1α and VEGF in swine GCs, while GPER antagonist (G15) inhibited the stimulating effect of E2 and G1. Meanwhile, G15 inhibited the stimulating effect of E2 and G1 on IL-6 mRNA expression and secretion. Furthermore, IL-6 antibody and AG490 (JAK2/STAT3 inhibitor) attenuated G1-induced HIF-1α and VEGF expression. In conclusion, this study revealed how estrogen-induced HIF-1α and VEGF expressions in swine GCs are mediated through GPER-derived IL-6 secretion leading to JAK2/STAT3 activation.