Human inositol polyphosphate multikinase regulates transcript-selective nuclear mRNA export to preserve genome
Vihandha O Wickramasinghe1, Jane M Savill, Sreenivas Chavali
1The Medical Research Council Cancer Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK.
Molecular Cell
|October 1, 2013
Summary
Inositol polyphosphate multikinase (IPMK) regulates the export of specific messenger RNAs (mRNAs) involved in DNA repair. This process is crucial for maintaining genome integrity in human cells.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Messenger RNA (mRNA) nuclear export is vital for eukaryotic gene expression.
- Specific mRNA export pathways remain incompletely understood.
- Genome integrity relies on efficient DNA repair mechanisms.
Purpose of the Study:
- To identify and characterize a transcript-selective nuclear export mechanism.
- To elucidate the role of inositol polyphosphate multikinase (IPMK) in this process.
- To understand how IPMK regulates transcripts involved in genome duplication and repair.
Main Methods:
- Studied transcripts encoding RAD51, a key DNA repair protein.
- Investigated the effect of IPMK depletion and catalytic inactivation on mRNA export.
- Analyzed the interaction between IPMK, RAD51 mRNA, and the export factor ALY.
- Utilized cell extracts to assess the role of phosphatidylinositol (3,4,5)-trisphosphate (PIP3).
Main Results:
- IPMK depletion selectively reduced RAD51 protein and RAD51 mRNA nuclear export.
- Impaired RAD51 mRNA export led to defective homologous recombination (HR).
- IPMK is required for the mRNA export factor ALY to recognize a motif in RAD51 transcripts.
- The IPMK product PIP3 restored ALY recognition in depleted cell extracts.
Conclusions:
- IPMK controls a transcript-selective mRNA export pathway.
- This pathway is regulated by phosphoinositide turnover.
- The IPMK-controlled pathway is essential for preserving genome integrity in humans.
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