A Neuronal Transcriptome Response Involving Stress Pathways is Buffered by Neuronal microRNAs

Abstract

A single microRNA (miRNA) can inhibit a large number of mRNA transcripts. This widespread regulatory function has been experimentally demonstrated for a number of miRNAs. However, even when a multitude of targets is confirmed, function of a miRNA is frequently interpreted through a prism of a handful arbitrarily selected “interesting” targets. In this work we first show that hundreds of transcripts with target sites for two miRNAs expressed endogenously in neurons, miR-124 and miR-434-3p, are coordinately upregulated in a variety of neuronal stresses. This creates a landscape where these two miRNAs can exert their widespread inhibitory potential on stress-induced transcripts. Next, we experimentally demonstrate that overexpression of these two miRNAs indeed significantly inhibits expression of hundreds of stress-induced transcripts, thus confirming that these transcripts are enriched in true targets of examined miRNAs. A number of miRNAs were previously shown to have important roles in the regulation of stress responses, and our results suggest that these roles should be understood in light of a wide spread activation of miRNA targets during stresses. Importantly, a popular cationic lipid transfection reagent triggers such induction of miRNA targets. Therefore, when a transfection paradigm is employed to study miRNA function, the results of such studies should be interpreted with consideration for the inadvertent induction of miRNA targets.

The Effect of MicroRNA-124 Overexpression on Anti-Tumor Drug Sensitivity

“…(D) MiR-124 regulates expression ATMIN and PARP1. Western blot of ATMIN and PARP1 in U-2 OS cells transiently transfected with the VC or miR-124-expressing vector (miR-124; upper panel), or with a 2′-O-methyl-modified antisense inhibitor of miR-124 (Anti-miR-124; lower panel) or 2′-O-methyl negative control (Anti-miR) [ 48 ]. Tubulin was included as a protein loading control, and the numbers indicate the expression relative to expression in the VC or Anti-miR control, measured by densitometry.…”

A microRNA signature of toxic extrasynaptic N-methyl-D-aspartate (NMDA) receptor signaling

“…Such a physiological function of TAMs remains to be investigated in future studies, especially given the relatively low expression levels of TAMs compared to other neuronal miRNAs [22]. It would, however, be in line with the emerging view of miRNAs acting as mediators and/or modulators of diverse forms of stress signaling in a variety of cells and tissues [60][61][62][63]. Regardless of their biological function, TAMs might be candidate molecules for biomarkers of neurodegeneration [52,64].…”

An updated role of microRNA-124 in central nervous system disorders: a review

“…A number of miRNAs are shown to have important roles in the regulation of stress responses, and indeed miRNAs are shown to impart robustness to stress responses. The capacity of miRNAs to inhibit 100s of transcripts that are activated by stress makes them candidates for stabilizers of the homeostatic state of the transcriptome ( Manakov et al, 2012 ).…”

“…However, miR-124 was not affected by stress in mouse PVN ( Mckennirey, 2011 ). In vitro , miR-124 from primary cultured neurons was significantly increased in response to all four neuronal challenge response sets (transfection, KCl, kainite, aging; Manakov et al, 2012 ).…”

“…Hundreds of transcripts endogenously expressed in neurons with target sites for miR-124 are coordinately upregulated in a variety of neuronal stresses. Overexpression of miR-124 indeed significantly inhibits expression of 100s of stress-induced transcripts detected by microarray ( Manakov et al, 2012 ). Glucocorticoid and its receptor (glucocorticoid receptor, GR) exert profound effects on a variety of physiological processes, including adaptation to stress.…”