The accumulation of damaged or misfolded proteins can have devastating effects on cellular physiology and viability. To protect itself, the cell possesses numerous Protein Quality Control (PQC) systems that minimize the persistence and detrimental effects of these aberrant proteins. While a variety of PQC systems have been characterized in the cytoplasm, ER, and mitochondria, how the nucleus manages aberrant proteins is poorly understood. But, understanding this fundamental aspect of nuclear biology is important because many age-correlated neuromuscular disorders (Huntington's, Kennedy's, several spinal-cerebellar ataxias) result from toxic accumulation of aberrant proteins in the nucleus. Therefore, our long-term goals are to understand how the nucleus normally protects itself from toxic aberrant proteins by identifying PQC systems that operate in the nucleus, characterizing how these systems recognize and target aberrant proteins, examining if lesions in nuclear PQC systems are required for these pathologies to develop, and determining the specific nuclear processes that are disrupted by aberrant nuclear proteins to cause toxicity. From our initial studies in S. cerevisiae, we've identified the first-known PQC degradation system that acts in the nucleus. The central player of this nuclear PQC system is San1, a nuclear-localized ubiquitin- protein ligase that targets aberrant nuclear proteins for ubiquitination and proteasome degradation. With the discovery of San1, we're now well positioned to explore how a nuclear PQC degradation system recognizes its substrates, and what it recognizes as aberrant within those substrates.
The specific aims for this grant are to: (1) Determine the regions within San1 responsible for substrate targeting. Mutagenesis of San1 will be used to identify in cis regions important for substrate recognition. (2) Determine the features of an aberrant protein recognized by San1. Mutagenesis of San1 substrates will be used to identify regions required for targeting by San1. (3) Identify &characterize additional components of the San1 pathway. A combination of genetic and biochemical approaches will be used to identify additional San1 pathway components.

Public Health Relevance

Many age-correlated neuromuscular disorders (Huntington's, Kennedy's, several spinal-cerebellar ataxias, and oculopharyngeal muscular dystrophy to name a few) result from toxic accumulation of aggregation-prone proteins in the cell's nucleus. Our goals are to understand how the nucleus normally protects itself from toxic aggregation-prone proteins, and why it fails to do so in these and other diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG031136-05
Application #
8423005
Study Section
Nuclear Dynamics and Transport (NDT)
Program Officer
Velazquez, Jose M
Project Start
2009-02-15
Project End
2014-01-31
Budget Start
2013-02-01
Budget End
2014-01-31
Support Year
5
Fiscal Year
2013
Total Cost
$282,374
Indirect Cost
$98,027
Name
University of Washington
Department
Pharmacology
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Oeser, Michelle L; Amen, Triana; Nadel, Cory M et al. (2016) Dynamic Sumoylation of a Conserved Transcription Corepressor Prevents Persistent Inclusion Formation during Hyperosmotic Stress. PLoS Genet 12:e1005809
Jones, Ramon D; Gardner, Richard G (2016) Protein quality control in the nucleus. Curr Opin Cell Biol 40:81-89
Jones, Ramon D; Gardner, Richard G (2015) Digging for Buried Amino Acids Unearths New Protein Quality Control Treasure. Structure 23:1151-2
Gallagher, Pamela S; Oeser, Michelle L; Abraham, Ayelet-chen et al. (2014) Cellular maintenance of nuclear protein homeostasis. Cell Mol Life Sci 71:1865-79
Gallagher, Pamela S; Clowes Candadai, Sarah V; Gardner, Richard G (2014) The requirement for Cdc48/p97 in nuclear protein quality control degradation depends on the substrate and correlates with substrate insolubility. J Cell Sci 127:1980-91
Fredrickson, Eric K; Clowes Candadai, Sarah V; Tam, Cheuk Ho et al. (2013) Means of self-preservation: how an intrinsically disordered ubiquitin-protein ligase averts self-destruction. Mol Biol Cell 24:1041-52
Fredrickson, Eric K; Gallagher, Pamela S; Clowes Candadai, Sarah V et al. (2013) Substrate recognition in nuclear protein quality control degradation is governed by exposed hydrophobicity that correlates with aggregation and insolubility. J Biol Chem 288:6130-9
Fredrickson, Eric K; Gardner, Richard G (2012) Selective destruction of abnormal proteins by ubiquitin-mediated protein quality control degradation. Semin Cell Dev Biol 23:530-7
Rosenbaum, Joel C; Fredrickson, Eric K; Oeser, Michelle L et al. (2011) Disorder targets misorder in nuclear quality control degradation: a disordered ubiquitin ligase directly recognizes its misfolded substrates. Mol Cell 41:93-106
Rosenbaum, Joel C; Gardner, Richard G (2011) How a disordered ubiquitin ligase maintains order in nuclear protein homeostasis. Nucleus 2:264-70

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