title: Roles of Hsp104 and trehalose in solubilisation of mutant huntingtin in heat shocked Saccharomyces cerevisiae cells.
abstract: Inhibition of huntingtin aggregation, either in the nucleus and/or in the cytosol, has been identified as a major strategy to ameliorate the symptoms of Huntington's disease. Chaperones and other protein stabilisers would thus be key players in ensuring the correct folding of the amyloidogenic protein and its expression in the soluble form. By transient activation of the global heat stress response in Saccharomyces cerevisiaeBY4742, we show that heterologous expression of mutant huntingtin (103Q-htt) could be modulated so that the protein was partitioned off in the soluble fraction of the cytosol. This led to lower levels of reactive oxygen species and improved cell viability. Previous reports had speculated on the relationship between trehalose and the heat shock response in ensuring enhanced cell survival but no direct evidence of such an interaction was available. Using mutants of an isogenic strain which do not express the major trehalose synthetic or metabolising enzymes or the chaperone, heat shock protein 104 (Hsp104), we were able to identify the functions of Hsp104 and the osmoprotectant trehalose in solubilising mutant huntingtin. We propose that the beneficial effect of the protein refolding machinery in solubilising the aggregation-prone protein is exerted by maintaining a tight balance between the trehalose synthetic enzyme, trehalose-6-phosphate synthase 1 and Hsp104. This ensures that the level of the osmoprotectant, trehalose, does not exceed the limit beyond which it is reported to inhibit protein refolding.
authors.affiliation: Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India.
authors.forename: Aliabbas A
authors.initials: AA
authors.lastname: Saleh
authors.affiliation: Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India.
authors.forename: Uma S
authors.initials: US
authors.lastname: Gune
authors.affiliation: Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India.
authors.forename: Rajeev Kumar
authors.initials: RK
authors.lastname: Chaudhary
authors.affiliation: Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India.
authors.forename: Ankit P
authors.initials: AP
authors.lastname: Turakhiya
authors.affiliation: Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India. Electronic address: ipsita@niper.ac.in.
authors.forename: Ipsita
authors.initials: I
authors.lastname: Roy
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival / Q000235:genetics; D018835:Chaperonin 10 / Q000096:biosynthesis* / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005964:Glucosyltransferases / Q000096:biosynthesis* / Q000378:metabolism; D018869:Heat-Shock Response / Q000502:physiology; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D014199:Trehalose / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D018835:Chaperonin 10; D009419:Nerve Tissue Proteins; D017382:Reactive Oxygen Species; D014199:Trehalose; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase
keywords: Heat shock; Hsp104; Protein misfolding; Thermotolerance; Trehalose