title: Regulatory role of the 90-kDa-heat-shock protein (Hsp90) and associated factors on gene expression.
abstract: The term molecular chaperone was first used to describe the ability of nucleoplasmin to prevent the aggregation of histones with DNA during the assembly of nucleosomes. Subsequently, the name was extended to proteins that mediate the post-translational assembly of oligomeric complexes protecting them from denaturation and/or aggregation. Hsp90 is a 90-kDa molecular chaperone that represents the major soluble protein of the cell. In contrast to most conventional chaperones, Hsp90 functions as a refined sensor of protein function and its principal role in the cell is to facilitate biological activity to properly folded client proteins that already have a preserved tertiary structure. Consequently, Hsp90 is related to basic cell functions such as cytoplasmic transport of soluble proteins, translocation of client proteins to organelles, and regulation of the biological activity of key signaling factors such as protein kinases, ubiquitin ligases, steroid receptors, cell cycle regulators, and transcription factors. A growing amount of evidence links the protective action of this molecular chaperone to mechanisms related to posttranslational modifications of soluble nuclear factors as well as histones. In this article, we discuss some aspects of the regulatory action of Hsp90 on transcriptional regulation and how this effect could have impacted genetic assimilation mechanism in some organisms.
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires/IQUIBICEN, Argentina.
authors.forename: Alejandra G
authors.initials: AG
authors.lastname: Erlejman
authors.affiliation: Laboratorio de Receptores Nucleares, Instituto de Biología y Medicina Experimental/CONICET, Buenos Aires, Argentina.
authors.forename: Mariana
authors.initials: M
authors.lastname: Lagadari
authors.affiliation: Laboratorio de Arquitectura Nuclear, Instituto de Biología y Medicina Experimental/CONICET, Buenos Aires, Argentina.
authors.forename: Judith
authors.initials: J
authors.lastname: Toneatto
authors.affiliation: Laboratorio de Arquitectura Nuclear, Instituto de Biología y Medicina Experimental/CONICET, Buenos Aires, Argentina.
authors.forename: Graciela
authors.initials: G
authors.lastname: Piwien-Pilipuk
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires/IQUIBICEN, Argentina; Laboratorio de Receptores Nucleares, Instituto de Biología y Medicina Experimental/CONICET, Buenos Aires, Argentina. Electronic address: mgali@qb.fcen.uba.ar.
authors.forename: Mario D
authors.initials: MD
authors.lastname: Galigniana
mesh_terms: D000818:Animals; D005786:Gene Expression Regulation; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008957:Models, Genetic; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; D014157:Transcription Factors
keywords: HDAC6; Hsp90; Immunophilin; Pih1; SmyD; Tah1