Synergistic regulation of Rgs4 mRNA by HuR and miR-26/RISC in neurons

Abstract

The negative regulator of G-protein signalling 4 (Rgs4) is linked to several neurologic diseases, e.g. schizophrenia, addiction, seizure and pain perception. Consequently, Rgs4 expression is tightly regulated, resulting in high mRNA and protein turnover. The post-transcriptional control of gene expression is mediated via RNAbinding proteins (RBPs) that interact with mRNAs in a combinatorial fashion. Here, we show that in neurons the RBP HuR reduces endogenous Rgs4 expression by destabilizing Rgs4 mRNA. Interestingly, in smooth muscle cells, Rgs4 is stabilized by HuR, indicating tissue-dependent differences in HuR function. Using in vitro RNA-based pulldown experiments, we identify the functional AU-rich element (ARE) within the Rgs4 3ʹ-UTR that is recognized and bound by HuR. Bioinformatic analysis uncovered that this ARE lies within a highly conserved area next to a miR-26 binding site. We find that the neuronal-enriched miR-26 negatively influences Rgs4 expression in neurons. Further, HuR and miR-26 act synergistically in fluorescent reporter assays. Together, our data suggest a regulatory mechanism, in which an RBP selectively destabilizes a target mRNA in cooperation with a miRNA and the RISC machinery.

The miR-26 family regulates neural differentiation-associated microRNAs and mRNAs by directly targeting REST

“…In mammals, miR-26 family members are encoded in the introns of genes encoding CTDSPs (miR-26a1 in CtdspL, miR-26a2 in Ctdsp2 and miR-26b in Ctdsp1). A role for miR-26 in the mammalian CNS in vivo and in vitro has previously been suggested (Ehses et al, 2020;Xie et al, 2019;Zhang et al, 2018). In contrast to these findings, miR-26-knockout (KO) mice display no obvious defects in brain development (Acharya et al, 2019;Sun et al, 2018;Zhang et al, 2017).…”

RGS4 RNA Secondary Structure Mediates Staufen2 RNP Assembly in Neurons

“…However, it did not mimic the reduction in GFP levels observed for the FL 3′-UTR upon Stau2 depletion. This effect points towards additional elements in the 3′-UTR of Rgs4 [ 40 ] that are affected by the deletion showing that 3′-UTRs are likely to be equipped with numerous sequence and structure motifs.…”

MicroRNAs, Tristetraprolin Family Members and HuR: A Complex Interplay Controlling Cancer-Related Processes

“…Although HuR has mainly been associated with a stabilizing function, this dogmatic view is further challenged by other studies showing cooperation between HuR and miRNAs in other diseases. For instance, HuR and miR-26 act synergistically to regulate the expression of the negative regulator of G-protein signaling 4 ( Rgs4 ) in neurons [ 140 ]. Whether this cooperation exists in human cancers remains to be determined, but these findings suggest that this destabilizing function of HuR is underestimated in cancers and may be tissue dependent.…”