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  • Author: Jia Sun x
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Jia Sun, Haiping Zhu, Xiaorong Wang, Qiuqi Gao, Zhuoying Li and Huiya Huang

The molecular signaling mechanisms of Coenzyme Q10 (CoQ10) in diabetic nephropathy (DN) remain poorly understood. We verified that mitochondrial abnormalities, like defective mitophagy, the generation of mitochondrial reactive oxygen species (mtROS) and the reduction of mitochondrial membrane potential, occurred in the glomerulus of db/db mice, accompanied by reduced PINK and parkin expression and increased apoptosis. These changes were partially reversed following oral administration of CoQ10. In inner fenestrated murine glomerular endothelial cells (mGECs), high glucose (HG) also resulted in deficient mitophagy, mitochondrial dysfunction and apoptosis, which were reversed by CoQ10. Mitophagy suppression mediated by Mdivi-1 or siPINK abrogated the renoprotective effects exerted by CoQ10, suggesting a beneficial role for CoQ10-restored mitophagy in DN. Mechanistically, CoQ10 restored the expression, activity and nuclear translocation of Nrf2 in HG-cultured mGECs. In addition, the reduced PINK and parkin expression observed in HG-cultured mGECs were partially elevated by CoQ10. CoQ10-mediated renoprotective effects were abrogated by the Nrf2 inhibitor ML385. When ML385 abolished mitophagy and the renoprotective effects exerted by CoQ10, mGECs could be rescued by treatment with mitoTEMPO, which is a mtROS-targeted antioxidant. These results suggest that CoQ10, as an effective antioxidant in mitochondria, exerts beneficial effects in DN via mitophagy by restoring Nrf2/ARE signaling. In summary, CoQ10-mediated mitophagy activation positively regulates DN through a mechanism involving mtROS, which influences the activation of the Nrf2/ARE pathway.

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Caiyun Sun, Da Duan, Bo Li, Chaobin Qin, Jirong Jia, Bin Wang, Haiyan Dong and Wensheng Li

Urotensin II (UII) is a cyclic peptide that was originally extracted from the caudal neurosecretory system (CNSS) of fish. UII is well known to exhibit cardiovascular, ventilatory, and motor effects in vertebrates. Studies have reported that UII exerts mitogenic effects and can act as an autocrine/paracrine growth factor in mammals. However, similar information in fish is limited. In this study, the full-length cDNAs of UII and its receptor (UT) were cloned and characterized in the orange-spotted grouper. UII and UT were expressed ubiquitously in various tissues in grouper, and particularly high levels were observed in the CNSS, CNS, and ovary. A functional study showed that UT was coupled with intracellular Ca2 + mobilization in HEK293 cells. Studies carried out using i.p. injections of UII in grouper showed the following: i) in the hypothalamus, UII can significantly stimulate the mRNA expression of ghrh and simultaneously inhibit the mRNA expression of somatostatin 1 (ss1) and ss2 3 h after injection; ii) in the pituitary, UII also significantly induced the mRNA expression of gh 6 and 12 h after injection; and iii) in the liver, the mRNA expression levels of ghr1/ghr2 and igf1/igf2 were markedly increased 12 and 3 h after the i.p. injection of UII respectively. These results collectively indicate that the UII/UT system may play a role in the promotion of the growth of the orange-spotted grouper.

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Wenpeng Dong, Ye Jia, Xiuxia Liu, Huan Zhang, Tie Li, Wenlin Huang, Xudong Chen, Fuchun Wang, Weixia Sun and Hao Wu

Oxidative stress contributes to the pathogenesis of diabetic nephropathy (DN). Nuclear factor erythroid 2-related factor 2 (NRF2) plays a key role in cellular defense against oxidative stress. NRF2 activators have shown promising preventive effects on DN. Sodium butyrate (NaB) is a known activator of NRF2. However, it is unknown whether NRF2 is required for NaB protection against DN. Therefore, streptozotocin-induced diabetic C57BL/6 Nrf2 knockout and their wild-type mice were treated in the presence or absence of NaB for 20 weeks. Diabetic mice, but not NaB-treated diabetic mice, developed significant renal oxidative damage, inflammation, apoptosis, fibrosis, pathological changes and albuminuria. NaB inhibited histone deacetylase (HDAC) activity and elevated the expression of Nrf2 and its downstream targets heme oxygenase 1 and NAD(P)H dehydrogenase quinone 1. Notably, deletion of the Nrf2 gene completely abolished NaB activation of NRF2 signaling and protection against diabetes-induced renal injury. Interestingly, the expression of Kelch-like ECH-associated protein 1, the negative regulator of NRF2, was not altered by NaB under both diabetic and non-diabetic conditions. Moreover, NRF2 nuclear translocation was not promoted by NaB. Therefore, the present study indicates, for the first time, that NRF2 plays a key role in NaB protection against DN. Other findings suggest that NaB may activate Nrf2 at the transcriptional level, possibly by the inhibition of HDAC activity.

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Dong-Xu Han, Chang-Jiang Wang, Xu-Lei Sun, Jian-Bo Liu, Hao Jiang, Yan Gao, Cheng-Zhen Chen, Bao Yuan and Jia-Bao Zhang

Circular RNAs (circRNAs) are a new class of RNA that have a stable structure characterized by covalently closed circular molecules and are involved in invasive pituitary adenomas and recurrent clinically nonfunctioning pituitary adenomas. However, information on circRNAs in the normal pituitary, especially in rats, is limited. In this study, we identified 4123 circRNAs in the immature (D15) and mature (D120) rat anterior pituitary using the Illumina platform, and 32 differentially expressed circRNAs were found. A total of 150 Gene Ontology terms were significantly enriched, and 16 KEGG pathways were found to contain differentially expressed genes. Moreover, we randomly selected eight highly expressed circRNAs and detected their relative expression levels in the mature and immature rat pituitary by qPCR. In addition, we predicted 90 interactions between 53 circRNAs and 57 miRNAs using miRanda. Notably, circ_0000964 and circ_0001303 are potential miRNA sponges that may regulate the Fshb gene. The expression profile of circRNAs in the immature and mature rat anterior pituitary may provide more information about the roles of circRNAs in the development and reproduction in mammals.

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Gen Chen, Xiangjuan Chen, Chao Niu, Xiaozhong Huang, Ning An, Jia Sun, Shuai Huang, Weijian Ye, Santie Li, Yingjie Shen, Jiaojiao Liang, Weitao Cong and Litai Jin

Baicalin is the major component found in Scutellaria baicalensis root, a widely used herb in traditional Chinese medicine, which exhibits strong anti-inflammatory, anti-viral and anti-tumor activities. The present work was devoted to elucidate the molecular and cellular mechanisms underlying the protective effects of Baicalin against diabetes-induced oxidative damage, inflammation and endothelial dysfunction. Diabetic mice, induced by streptozotocin (STZ), were treated with intraperitoneal Baicalin injections. Human umbilical vein endothelial cells (HUVECs) were cultured either in normal glucose (NG, 5.5 mM) or high glucose (HG, 33 mM) medium in the presence or absence of Baicalin for 72 h. We observed an obvious inhibition of hyperglycemia-triggered oxidative damage and inflammation in HUVECs and diabetic aortal vasculature by Baicalin, along with restoration of hyperglycemia-impaired nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway activity. However, the protective effects of Baicalin almost completely abolished in HUVECs transduced with shRNA against Nrf2, but not with nonsense shRNA. Mechanistic studies demonstrated that HG decreased Akt and GSK3B phosphorylation, restrained nuclear export of Fyn and nuclear localization of Nrf2, blunted Nrf2 downstream target genes and subsequently induced oxidative stress in HUVECs. However, those destructive cascades were well prevented by Baicalin in HUVECs. Furthermore, LY294002 and ML385 (inhibitor of PI3K and Nrf2) attenuated Baicalin-mediated Nrf2 activation and the ability of facilitates angiogenesis in vivo and ex vivo. Taken together, the endothelial protective effect of Baicalin under hyperglycemia condition could be partly attributed to its role in downregulating reactive oxygen species (ROS) and inflammation via the Akt/GSK3B/Fyn-mediated Nrf2 activation.