MRNA export: threading the needle

Ouassila Gaouar,Hugo Germain

doi:10.3389/fpls.2013.00059

Abstract

After mRNA biogenesis, several proteins interact with the messenger to ensure its proper export to the cytoplasm. Some of these proteins will bind RNA early on, at the onset of transcription by RNA polymerase II holoenzyme, while others will join later for downstream processing steps, such as poly-adenylation or splicing, or may direct mRNA ribonucleoprotein particle migration to the nucleopore. We recently discovered that Arabidopsis plant knockout for the protein MOS11 (MODIFIER OF SNC1, 11) partially suppresses autoimmune responses observed in the TNL-type [TIR/NBS/LRR (Toll-interleukin-like receptor/nucleotide-binding site/C-terminal leucine-rich repeat)] R gene gain-of-function variant snc1 (suppressor of npr1-1, constitutive 1). This suppression of resistance to pathogens appears to be caused by a decrease in nuclear mRNA export in mos11-1 snc1 plants. In humans, the putative ortholog of MOS11, CIP29 (29-kDa cytokine-induced protein), interacts with three proteins that are also involved in mRNA export: DDX39 (DEAD-box RNA helicase), TAF15 of the FUS family (FUSED IN SARCOMA), and ALY (ALWAYS EARLY), a protein implicated in mRNA export in mammalian systems. These proteins have received very little attention in plants. Here, we will discuss their particularities and role in mRNA export and biotic stress.

Highlights

Messenger RNA export is a tightly regulated process, unique to eukaryotes, that enhances control over the timing and level of translation
Since TAF15b does not contain any conserved catalytic domain that would provide insight into its putative molecular function, we investigated whether it has an effect on mRNA export
LOS4 has been shown to be required for mRNA export in a temperaturedependent manner, and LOS4–GFP fusion accumulates at the nuclear envelope (NE) (Gong et al, 2002, 2005) where it may be involved in messenger ribonucleoprotein particle (mRNP) remodeling

Summary

Introduction

Messenger RNA export is a tightly regulated process, unique to eukaryotes, that enhances control over the timing and level of translation. MOS2, discovered in a snc1 modifier screen, is the first protein potentially involved in mRNA export (Zhang et al, 2005). MOS3 ( called SAR3/AtNup96), another protein discovered in snc1 modifier screen (Zhang and Li, 2005), is an integral NP component of the conserved Nup107–Nup160 complex shown to be required for mRNA export (Parry et al, 2006).

Results

Conclusion