LncRNA SNHG4 sponges miR-200b to inhibit cell apoptosis in diabetic retinopathy

This study aimed to investigate the role of long non-coding RNA (lncRNA) small nucleolar RNA host gene 4 (SNHG4) in diabetic retinopathy (DR). We found that SNHG4 was downregulated in DR. SNHG4 could directly interact with miR-200b, while overexpression of miR-200b did not affect the expression of SNHG4 in human retinal pigment epithelial cells ARPE-19. In contrast, overexpression of SNHG4 led to the upregulation of oxidation resistance 1 (Oxr1), a target of miR-200b. Cell apoptosis analysis showed that overexpression of miR-200b increased the apoptotic rate of ARPE-19 cells under high glucose treatment. Oxr1 and SNHG4 played opposite roles and reduced the effects of overexpression of miR-200b. In conclusion, SNHG4 may sponge miR-200b to inhibit cell apoptosis in DR by upregulating Oxr1.

Oxr1a prevents the premature ovarian failure by regulating oxidative stress and mitochondrial function in zebrafish

Premature ovarian failure (POF) is characterized as the ovarian dysfunction and defective oocyte development. In POF patients, ROS level is reported to be significantly higher than normal individuals. However, the involvement of oxidative stress in POF and the regulatory mechanisms underlying the antioxidative process in oocyte development remain largely unknown. Here, we discover that oxidation resistance 1a (Oxr1a), the ortholog of mammalian Oxr1, protects the oocytes of female zebrafish against oxidative stress and thus represses the POF phenotype. Oxr1a was widely expressed in oocytes at different developmental stages, of which the mRNA expression levels were significantly upregulated upon follicle activation and oocyte maturation. Oxr1a knockout exacerbated the POF phenotype, as evidenced by the decreased number and quality of oocytes. Moreover, the oocytes of oxr1a knockout zebrafish exhibited excessive ROS, increased mitochondrial DNA damage, reduced mitochondria, and abnormal morphology. Mechanistically, instead of decomposing ROS directly, Oxr1a participated in the process of oxidative stress through regulating the mRNA expression levels of the key antioxidant enzymes Cat and Sod1. Moreover, treatment with antioxidant N-Acetyl-l-cysteine attenuated the mitochondrial oxidative damage and improved the fertility of mutant females, indicating that Oxr1a may mediates the Sod1/Cat pathway to metabolize the intracellular ROS and avoid the mitochondrial oxidative damage, thus ensuring the normal development and maturation of oocytes. Taken together, these findings are useful for the elucidation of molecular mechanisms underlying the oxidative damage in oocytes and beneficial to the clinical therapeutics of POF.

MicroRNA-29a Mitigates Osteoblast Senescence and Counteracts Bone Loss through Oxidation Resistance-1 Control of FoxO3 Methylation

Senescent osteoblast overburden accelerates bone mass loss. Little is understood about microRNA control of oxidative stress and osteoblast senescence in osteoporosis. We revealed an association between microRNA-29a (miR-29a) loss, oxidative stress marker 8-hydroxydeoxyguanosine (8-OHdG), DNA hypermethylation marker 5-methylcystosine (5mC), and osteoblast senescence in human osteoporosis. miR-29a knockout mice showed low bone mass, sparse trabecular microstructure, and osteoblast senescence. miR-29a deletion exacerbated bone loss in old mice. Old miR-29a transgenic mice showed fewer osteoporosis signs, less 5mC, and less 8-OHdG formation than age-matched wild-type mice. miR-29a overexpression reversed age-induced senescence and osteogenesis loss in bone-marrow stromal cells. miR-29a promoted transcriptomic landscapes of redox reaction and forkhead box O (FoxO) pathways, preserving oxidation resistance protein-1 (Oxr1) and FoxO3 in old mice. In vitro, miR-29a interrupted DNA methyltransferase 3b (Dnmt3b)-mediated FoxO3 promoter methylation and senescence-associated β-galactosidase activity in aged osteoblasts. Dnmt3b inhibitor 5'-azacytosine, antioxidant N-acetylcysteine, or Oxr1 recombinant protein attenuated loss in miR-29a and FoxO3 to mitigate oxidative stress, senescence, and mineralization matrix underproduction. Taken together, miR-29a promotes Oxr1, compromising oxidative stress and FoxO3 loss to delay osteoblast aging and bone loss. This study sheds light on a new antioxidation mechanism by which miR-29a protects against osteoblast aging and highlights the remedial effects of miR-29a on osteoporosis.

Microarray-assisted fine mapping of quantitative trait loci on chromosome 15 for susceptibility to seizure-induced cell death in mice

Prior studies with crosses of the FVB/NJ (FVB; seizure-induced cell death-susceptible) mouse and the C57BL/6J (B6; seizure-induced cell death-resistant) mouse revealed the presence of a quantitative trait locus (QTL) on chromosome 15 that influenced susceptibility to kainic acid-induced cell death (Sicd2). In an earlier study, we confirmed that the Sicd2 interval harbors gene(s) conferring strong protection against seizure-induced cell death through the creation of the FVB.B6-Sicd2 congenic strain, and created three interval-specific congenic lines (ISCLs) that encompass Sicd2 on chromosome 15 to fine-map this locus. To further localise this Sicd2 QTL, an additional congenic line carrying overlapping intervals of the B6 segment was created (ISCL-4), and compared with the previously created ISCL-1-ISCL-3 and assessed for seizure-induced cell death phenotype. Whereas all of the ISCLs showed reduced cell death associated with the B6 phenotype, ISCL-4, showed the most extensive reduction in seizure-induced cell death throughout all hippocampal subfields. In order to characterise the susceptibility loci on Sicd2 by use of this ISCL and identify compelling candidate genes, we undertook an integrative genomic strategy of comparing exon transcript abundance in the hippocampus of this newly developed chromosome 15 subcongenic line (ISCL-4) and FVB-like littermates. We identified 10 putative candidate genes that are alternatively spliced between the strains and may govern strain-dependent differences in susceptibility to seizure-induced excitotoxic cell death. These results illustrate the importance of identifying transcriptomics variants in expression studies, and implicate novel candidate genes conferring susceptibility to seizure-induced cell death.