Regulation of miR-146a by RelA/NFkB and p53 in STHdhQ111/HdhQ111 Cells, a Cell Model of Huntington's Disease

Abstract

Huntington's disease (HD) is caused by the expansion of N-terminal polymorphic poly Q stretch of the protein huntingtin (HTT). Deregulated microRNAs and loss of function of transcription factors recruited to mutant HTT aggregates could cause characteristic transcriptional deregulation associated with HD. We observed earlier that expressions of miR-125b, miR-146a and miR-150 are decreased in STHdhQ111/HdhQ111 cells, a model for HD in comparison to those of wild type STHdhQ7/HdhQ7 cells. In the present manuscript, we show by luciferase reporter assays and real time PCR that decreased miR-146a expression in STHdhQ111/HdhQ111 cells is due to decreased expression and activity of p65 subunit of NFkB (RelA/NFkB). By reporter luciferase assay, RT-PCR and western blot analysis, we also show that both miR-150 and miR-125b target p53. This partially explains the up regulation of p53 observed in HD. Elevated p53 interacts with RelA/NFkB, reduces its expression and activity and decreases the expression of miR-146a, while knocking down p53 increases RelA/NFkB and miR-146a expressions. We also demonstrate that expression of p53 is increased and levels of RelA/NFkB, miR-146a, miR-150 and miR-125b are decreased in striatum of R6/2 mice, a mouse model of HD and in cell models of HD. In a cell model, this effect could be reversed by exogenous expression of chaperone like proteins HYPK and Hsp70. We conclude that (i) miR-125b and miR-150 target p53, which in turn regulates RelA/NFkB and miR-146a expressions; (ii) reduced miR-125b and miR-150 expressions, increased p53 level and decreased RelA/NFkB and miR-146a expressions originate from mutant HTT (iii) p53 directly or indirectly regulates the expression of miR-146a. Our observation of interplay between transcription factors and miRNAs using HD cell model provides an important platform upon which further work is to be done to establish if such regulation plays any role in HD pathogenesis.

MicroRNA‐432 contributes to dopamine cocktail and retinoic acid induced differentiation of human neuroblastoma cells by targeting NESTIN and RCOR1 genes

“…We have chosen 96 miRNAs from our earlier studies [15,25], bioinformatics analysis (http://miRNAMap.mbc.nctu.edu.tw/) and BrdU incorporation, at day 3 and 7 by treatment with DC and RA (n = 4). Symbols ⁄ , ⁄⁄ and ⁄⁄⁄ represent statistical significance P 6 0.05, P 6 0.01 and P 6 0.001respectively.…”

Astrocytes expressing ALS‐linked mutant FUS induce motor neuron death through release of tumor necrosis factor‐alpha

“…Dysregulation of NF‐κB has been linked to cancer and neurodegenerative diseases such as Huntington's (Ghose, Sinha, Das, Jana, & Bhattacharyya, 2011) and ALS (Frakes et al, 2014; Prell et al, 2014). Interestingly, FUS augments NF‐ĸB‐dependent gene expression induced by physiological stimuli such as TNFα (Uranishi, 2001).…”

Epigenetic Mechanisms of Neurodegeneration in Huntington's Disease

“…These studies suggest additional mechanisms through which deregulation of miRNA biogenesis may contribute to posttranscriptional malfunction in HD [83,84]. Furthermore, a recent study by Ghose et al [85] suggests that mthtt decreases the expression of miR-125b and miR-15. As miR-125b and miR-15 are known to negatively regulate the expression of p53, these down-regulated miRNAs lead to increased levels of p53 which, in turn, decrease nuclear factor kappa B (NFκB)/p65 expression (RelA/NFκB), NFκB activity, and miR-146a expression.…”