The PARN Deadenylase Targets a Discrete Set of mRNAs for Decay and Regulates Cell Motility in Mouse Myoblasts

Abstract

PARN is one of several deadenylase enzymes present in mammalian cells, and as such the contribution it makes to the regulation of gene expression is unclear. To address this, we performed global mRNA expression and half-life analysis on mouse myoblasts depleted of PARN. PARN knockdown resulted in the stabilization of 40 mRNAs, including that encoding the mRNA decay factor ZFP36L2. Additional experiments demonstrated that PARN knockdown induced an increase in Zfp36l2 poly(A) tail length as well as increased translation. The elements responsible for PARN-dependent regulation lie within the 3′ UTR of the mRNA. Surprisingly, changes in mRNA stability showed an inverse correlation with mRNA abundance; stabilized transcripts showed either no change or a decrease in mRNA abundance. Moreover, we found that stabilized mRNAs had reduced accumulation of pre–mRNA, consistent with lower transcription rates. This presents compelling evidence for the coupling of mRNA decay and transcription to buffer mRNA abundances. Although PARN knockdown altered decay of relatively few mRNAs, there was a much larger effect on global gene expression. Many of the mRNAs whose abundance was reduced by PARN knockdown encode factors required for cell migration and adhesion. The biological relevance of this observation was demonstrated by the fact that PARN KD cells migrate faster in wound-healing assays. Collectively, these data indicate that PARN modulates decay of a defined set of mRNAs in mammalian cells and implicate this deadenylase in coordinating control of genes required for cell movement.

A poly(A)-specific ribonuclease directly regulates the poly(A) status of mitochondrial mRNA in Arabidopsis

“…The ahg2-1 mutation enhances sensitivity to both phytohormones, a phenotype that has been rarely reported 22 . Our present study showed that this phenotype is caused by dysfunction of mitochondria, supporting the idea that mitochondria have roles in stress responses in plants 37,38 . In addition, given the ahg2-1 phenotype of abnormal crosstalk between ABA and SA, it is presumed that mitochondria are involved in the integration of various stress signals in plants.…”

Positive and negative feedback loops in the p53 and mRNA 3′ processing pathways

“…PARN, an mRNA decay enzyme, has been studied extensively in vitro at the biochemical levels but very little is known of its biological targets and its role in different cellular conditions. Recently, it has been shown that PARN regulates the expression of genes involved in mRNA metabolism, transcription, and cell motility in mouse myoblasts (6). Our studies indicate that the CstF/PARN complex can decrease the mRNA levels of housekeeping genes under DNA-damaging conditions and of genes involved in cell growth and differentiation under nonstress conditions (5).…”

Poly(A)-specific ribonuclease deficiency impacts telomere biology and causes dyskeratosis congenita

“…Elsewhere, PARN knockdown in HeLa cells showed that genes involved in the p53 signalling pathway were most significantly affected (24). However, in mouse myoblasts, Lee et al (38) reported no changes in the p53 signalling pathway upon PARN knockdown but did observe reduced abundance of telomere maintenance genes, including Terf1, Terf2, and Rtel1. These observations from independent studies, including our own, suggest that PARN deficiency has an effect on p53 and telomere biology, but in a cell-specific manner.…”