title: Essential genetic interactors of SIR2 required for spatial sequestration and asymmetrical inheritance of protein aggregates.
abstract: Sir2 is a central regulator of yeast aging and its deficiency increases daughter cell inheritance of stress- and aging-induced misfolded proteins deposited in aggregates and inclusion bodies. Here, by quantifying traits predicted to affect aggregate inheritance in a passive manner, we found that a passive diffusion model cannot explain Sir2-dependent failures in mother-biased segregation of either the small aggregates formed by the misfolded Huntingtin, Htt103Q, disease protein or heat-induced Hsp104-associated aggregates. Instead, we found that the genetic interaction network of SIR2 comprises specific essential genes required for mother-biased segregation including those encoding components of the actin cytoskeleton, the actin-associated myosin V motor protein Myo2, and the actin organization protein calmodulin, Cmd1. Co-staining with Hsp104-GFP demonstrated that misfolded Htt103Q is sequestered into small aggregates, akin to stress foci formed upon heat stress, that fail to coalesce into inclusion bodies. Importantly, these Htt103Q foci, as well as the ATPase-defective Hsp104Y662A-associated structures previously shown to be stable stress foci, co-localized with Cmd1 and Myo2-enriched structures and super-resolution 3-D microscopy demonstrated that they are associated with actin cables. Moreover, we found that Hsp42 is required for formation of heat-induced Hsp104Y662A foci but not Htt103Q foci suggesting that the routes employed for foci formation are not identical. In addition to genes involved in actin-dependent processes, SIR2-interactors required for asymmetrical inheritance of Htt103Q and heat-induced aggregates encode essential sec genes involved in ER-to-Golgi trafficking/ER homeostasis.
authors: School of Life Science and Technology, Harbin Institute of Technology, Harbin, China.
authors: Jia
authors: J
authors: Song
authors: School of Life Science and Technology, Harbin Institute of Technology, Harbin, China.
authors: Qian
authors: Q
authors: Yang
authors: Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
authors: Junsheng
authors: J
authors: Yang
authors: Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
authors: Lisa
authors: L
authors: Larsson
authors: Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
authors: Xinxin
authors: X
authors: Hao
authors: Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden.
authors: Xuefeng
authors: X
authors: Zhu
authors: Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
authors: Sandra
authors: S
authors: Malmgren-Hill
authors: Mathematical Sciences, University of Gothenburg, Gothenburg, Sweden; Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden.
authors: Marija
authors: M
authors: Cvijovic
authors: Centre for Cellular Imaging, University of Gothenburg, Göteborg, Sweden.
authors: Julia
authors: J
authors: Fernandez-Rodriguez
authors: Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
authors: Julie
authors: J
authors: Grantham
authors: Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden.
authors: Claes M
authors: CM
authors: Gustafsson
authors: School of Life Science and Technology, Harbin Institute of Technology, Harbin, China; Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
authors: Beidong
authors: B
authors: Liu
authors: Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
authors: Thomas
authors: T
authors: Nyström
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics* / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D002455:Cell Division / Q000235:genetics; D016764:Cell Polarity / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D006360:Heat-Shock Proteins / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism; D024701:Myosin Type V / Q000378:metabolism; D066329:Protein Aggregates / Q000235:genetics*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D056565:Sirtuin 2 / Q000235:genetics* / Q000378:metabolism
chemical_list: D000199:Actins; C505601:CMD1 protein, S cerevisiae; D002147:Calmodulin; C098005:HSP42 protein, S cerevisiae; D006360:Heat-Shock Proteins; C077512:MYO2 protein, S cerevisiae; D066329:Protein Aggregates; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; C070972:HsP104 protein, S cerevisiae; C087778:SIR2 protein, S cerevisiae; D056565:Sirtuin 2; D024701:Myosin Type V; D018995:Myosin Heavy Chains