Genome-wide RNA interference screen identifies previously undescribed regulators of polyglutamine aggregation

doi:10.1073/pnas.0307697101

Genome-wide RNA interference screen identifies previously undescribed regulators of polyglutamine aggregation

^*Division of Functional Genomics, Hubrecht Laboratories/Netherlands Institute for Developmental Biology, 3584 CT Utrecht, The Netherlands; and ^‡Department of Biochemistry, Molecular Biology, and Cell Biology, Rice Institute for Biomedical Research, Northwestern University, Evanston, IL 60208

Edited by A. L. Horwich, Yale University School of Medicine, New Haven, CT (received for review November 19, 2003)

Abstract

Protein misfolding and the formation of aggregates are increasingly recognized components of the pathology of human genetic disease and hallmarks of many neurodegenerative disorders. As exemplified by polyglutamine diseases, the propensity for protein misfolding is associated with the length of polyglutamine expansions and age-dependent changes in protein-folding homeostasis, suggesting a critical role for a protein homeostatic buffer. To identify the complement of protein factors that protects cells against the formation of protein aggregates, we tested transgenic Caenorhabditis elegans strains expressing polyglutamine expansion yellow fluorescent protein fusion proteins at the threshold length associated with the age-dependent appearance of protein aggregation. We used genome-wide RNA interference to identify genes that, when suppressed, resulted in the premature appearance of protein aggregates. Our screen identified 186 genes corresponding to five principal classes of polyglutamine regulators: genes involved in RNA metabolism, protein synthesis, protein folding, and protein degradation; and those involved in protein trafficking. We propose that each of these classes represents a molecular machine collectively comprising the protein homeostatic buffer that responds to the expression of damaged proteins to prevent their misfolding and aggregation.

Footnotes

↵ § To whom correspondence may be addressed. E-mail: r-morimoto{at}northwestern.edu or plasterk{at}niob.knaw.nl.
↵ † E.A.A.N., S.M.G., R.I.M., and R.H.A.P. contributed equally to this work.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: RNAi, RNA interference; YFP, yellow fluorescent protein; Q stretch, polyglutamine stretch; Qn, Q stretch of n residues; FRAP, fluorescence recovery after photo-bleaching; dsRNA, double-stranded RNA.