No abstract

The kidney is vulnerable to hypoxia-induced injury. One of the mechanisms underlying this phenomenon is cell apoptosis triggered by hypoxia-inducible factor-1-α (HIF-1α) activation. ) is known to be induced by HIF-1α and can regulate various pathological processes, but its role in hypoxic kidney injury remains unclear. Here, in both rat systemic hypoxia and local kidney hypoxia models, we found miR-210 levels were upregulated significantly in injured kidney, especially in renal tubular cells. A similar increase was observed in hypoxia-treated human renal tubular HK-2 cells. We also verified that miR-210 can directly suppress HIF-1α expression by targeting the 3′ untranslated region of HIF-1α mRNA in HK-2 cells in severe hypoxia. Accordingly, miR-210 overexpression caused significant inhibition of the HIF-1α pathway and attenuated apoptosis caused by hypoxia, while miR-210 knockdown exerted the opposite effect. Taken together, our findings verify that miR-210 is involved in the molecular response in hypoxic kidney lesions in vivo and attenuates hypoxia-induced renal tubular cell apoptosis by targeting HIF-1α directly and suppressing HIF-1α pathway activation in vitro.

This study aimed to determine the effects of Bifidobacterium bifidum TMC3115, Lactobacillus plantarum 45 (LP45) and their combined use on cognitive performance and gut microbiota in APP/PS1 mice. The APP/PS1 mice were randomly divided into four groups: Alzheimer's disease (AD) model group, TMC3115 group [1 × 109 colony forming unit (CFU)], LP45 group (1 × 109 CFU) and a mixture group of TMC3115 (5 × 108 CFU) and LP45 (5 × 108 CFU). The wild-type littermates were chosen as normal control. The mice were sacrificed at the end of 22 weeks after behavioral evaluation. Collected cecum content was analyzed using 16S rRNA sequencing. Combined use of TMC3115 and LP45 significantly increased the times across the platform, time spent in the target quadrant compared with the AD, TMC3115 and LP45 groups in Morris water maze test. Microbiota analysis showed that combined TMC3115 and LP45 supplementation significantly increased observed species and beta diversity, and reversed gut dysbiosis by decreasing the abundance of Bacteroides and increasing the abundance of Acetatifactor and Millionella. These results indicate the long-term combined administration of TMC3115 and LP45 can improve spatial memory impairment in APP/PS1 mice and suggest that modifying the gut microbiome may provide potential benefits for AD patients.

Mitophagy is an important metabolic mechanism that modulates mitochondrial quality and quantity by selectively removing damaged or unwanted mitochondria. BNIP3 (BCL2/adenovirus e1B 19 kDa protein interacting protein 3), a mitochondrial outer membrane protein, is a mitophagy receptor that mediates mitophagy under various stresses, particularly hypoxia, since BNIP3 is a hypoxia-responsive protein. However, the underlying mechanisms that regulate BNIP3 and thus mediate mitophagy under hypoxic conditions remain elusive. Here, we demonstrate that in hypoxia JNK1/2 (c-Jun N-terminal kinase 1/2) phosphorylates BNIP3 at Ser 60/Thr 66, which hampers proteasomal degradation of BNIP3 and drives mitophagy by facilitating the direct binding of BNIP3 to LC3 (microtubule-associated protein 1 light chain 3), while PP1/2A (protein phosphatase 1/2A) represses mitophagy by dephosphorylating BNIP3 and triggering its proteasomal degradation. These findings reveal the intrinsic mechanisms cells use to regulate mitophagy via the JNK1/2-BNIP3 pathway in response to hypoxia. Thus, the JNK1/2-BNIP3 signaling pathway strongly links mitophagy to hypoxia and may be a promising therapeutic target for hypoxia-related diseases.

Oxidative injury is involved in many diseases, including ischemic and neurodegenerative diseases. Antioxidant drugs can be used to relieve the oxidative injury caused by these diseases; however, there are very few antioxidant drugs available for clinical use. In this study, we found that 5-(hydroxymethyl)-2-furfural (5-HMF) protects against the oxidative damage induced by cerebral ischemia in rats or by hydrogen peroxide (H2O2) in PC12 cells. We demonstrated that 5-HMF performs this function via apurinic/apyrimidinic endonuclease/redox factor-1 (APE/Ref-1). APE/Ref-1 is a multifunctional protein involved in oxidative DNA damage repair through the base excision repair (BER) pathway and in the regulation of the DNA-binding activity of several transcription factors. The current study focused on the role of APE/Ref-1 in the antioxidative properties of 5-HMF. The results show that 5-HMF inhibited the reduction of APE/Ref-1 protein level caused by cerebral ischemia-reperfusion injury in rats or H2O2 treatment in PC12 cells. Treatment with an APE/Ref-1 inhibitor blocked 5-HMF-induced protection, suggesting that APE/Ref-1's DNA repair function contributes to antioxidation. In conclusion, this study suggests that APE/Ref-1 may be a potential target for antioxidant drugs.

No abstract

WIP1, as a critical phosphatase, plays many important roles in various physiological and pathological processes through dephosphorylating different substrate proteins. However, the functions of WIP1 in adipogenesis and fat accumulation are not clear. Here, we report that WIP1-deficient mice show impaired body weight growth, dramatically decreased fat mass, and significantly reduced triglyceride and leptin levels in circulation. This dysregulation of adipose development caused by the deletion of WIP1 occurs as early as adipogenesis. In contrast, lentivirus-mediated WIP1 phosphatase overexpression significantly increases the adipogenesis of pre-adipocytes via an enzymatic activity-dependent mechanism. PPARγ is a master gene of adipogenesis, and the phosphorylation of PPARγ at serine 112 strongly inhibits adipogenesis; however, very little is known about the negative regulation of this phosphorylation. Here, we show that WIP1 phosphatase plays a pro-adipogenic role by interacting directly with PPARγ and dephosphorylating p-PPARγ S112 in vitro and in vivo.

Hypoxia is the most critical factor for maintaining stemness. During embryonic development, neural stem cells (NSCs) reside in hypoxic niches, and different levels of oxygen pressure and time of hypoxia exposure play important roles in the development of NSCs. Such hypoxic niches exist in adult brain tissue, where the neural precursors originate. Hypoxia-inducible factors (HIFs) are key transcription heterodimers consisting of regulatory α-subunits (HIF-1α, HIF-2α, HIF-3α) and a constitutive β-subunit (HIF-β). Regulation of downstream targets determines the fate of NSCs. In turn, the stability of HIFs-α is regulated by prolyl hydroxylases (PHDs), whose activity is principally modulated by PHD substrates like oxygen (O2), α-ketoglutarate (α-KG), and the co-factors ascorbate (ASC) and ferrous iron (Fe2+). It follows that the transcriptional activity of HIFs is actually determined by the contents of O2, α-KG, ASC, and Fe2+. In normoxia, HIFs-α are rapidly degraded via the ubiquitin-proteasome pathway, in which PHDs, activated by O2, lead to hydroxylation of HIFs-α at residues 402 and 564, followed by recognition by the tumor suppressor protein von Hippel–Lindau (pVHL) as an E3 ligase and ubiquitin labeling. Conversely, in hypoxia, the activity of PHDs is inhibited by low O2 levels and HIFs-α can thus be stabilized. Hence, suppression of PHD activity in normoxic conditions, mimicking the effect of hypoxia, might be beneficial for preserving the stemness of NSCs, and it is clinically relevant as a therapeutic approach for enhancing the number of NSCs in vitro and for cerebral ischemia injury in vivo. This study will review the putative role of PHD inhibitors on the self-renewal of NSCs.