Pat1 RNA-binding proteins: Multitasking shuttling proteins

Area of Science:

• Molecular Biology
• Gene Expression Regulation
• RNA Biology

Background:

• Post-transcriptional gene regulation occurs via splicing, translation, and mRNA decay.
• RNA-binding factors regulate specific transcripts by influencing these processes.
• The Pat1 family of RNA-binding proteins is conserved across species and plays roles in mRNA decay and translation.

Purpose of the Study:

• To review the functions of the Pat1 family of RNA-binding proteins.
• To highlight the association of Pat1 with Lsm complexes in distinct cellular compartments.
• To discuss the role of Pat1b in the decay of AU-rich mRNAs.

Main Methods:

• Literature review focusing on Pat1 protein functions.
• Analysis of Pat1 protein interactions with Lsm complexes (Lsm1-7 and Lsm2-8).
• Examination of Pat1b's role in mRNA decay, particularly AU-rich elements.

Main Results:

• Pat1 proteins enhance mRNA decapping by Dcp1/2, promoting mRNA decay and translational repression.
• Pat1 proteins localize to cytoplasmic P-bodies and nuclear Cajal bodies/splicing speckles.
• The cytosolic Pat1/Lsm1-7 complex mediates mRNA decay, while the nuclear Pat1/Lsm2-8 complex influences alternative splicing.
• Human Pat1b specifically targets AU-rich mRNAs for decay, contrasting with DDX6's action on GC-rich mRNAs.

Conclusions:

• Pat1 proteins are crucial regulators of mRNA turnover and splicing through distinct Lsm complexes.
• The paralogous nature of complexes allows Pat1 to impact diverse cellular processes.
• Pat1b's specificity for AU-rich mRNAs has implications for understanding mRNA decay pathways and P-body function.