14-3-3zeta is indispensable for aggregate formation of polyglutamine-expanded huntingtin protein.
Huntington's disease (HD) is an autosomal dominant progressive neurodegenerative disorder caused by polyglutamine (polyQ) expansions in the huntingtin (Htt) protein. A hallmark of HD is the presence of aggregates-predominantly composed of NH(2)-terminal fragments of polyQ-expanded Htt-in the nucleus and cytoplasm of affected neurons. We previously proposed that 14-3-3zeta might act as a sweeper of misfolded proteins by facilitating the formation of aggregates possibly for neuroprotection; these aggregates are referred to as inclusion bodies. However, evidence available in this regard is indirect and circumstantial. In this study, analysis of the aggregation-prone protein Htt encoded by HD gene exon 1 containing polyglutamine expansions (Htt86Q) revealed that 17 residues in the NH(2)-terminal of this protein are indispensable for its aggregate formation. Immunoprecipitation assays revealed that 14-3-3beta, gamma, eta, and zeta interact with Htt86Q transfected in N2a cells. Interestingly, the small interfering ribonucleic acid (siRNA) suppression of 14-3-3zeta exclusively abolished Htt86Q aggregate formation, whereas 14-3-3beta or eta siRNA suppression did not. This indicates that 14-3-3zeta participates in aggregate formation under nonnative conditions. Our data support a novel role for 14-3-3zeta in the aggregate formation of nonnative, aggregation-prone proteins.
Omi
Kazuya
K
Department of Neurophysiology, Tokyo Medical University, Shinjuku-ku, Tokyo 160-8402, Japan.
Hachiya
Naomi S
NS
Tanaka
Mayumi
M
Tokunaga
Katsushi
K
Kaneko
Kiyotoshi
K
D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000503:physiopathology; D015536:Down-Regulation / Q000235:genetics; D005091:Exons / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D002479:Inclusion Bodies / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016716:PC12 Cells; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D051381:Rats; D019680:Trinucleotide Repeat Expansion / Q000235:genetics
D048948:14-3-3 Proteins; C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; D020033:Protein Isoforms; D034741:RNA, Small Interfering; C097188:polyglutamine