How CHIP ensures health and wellbeing across the life-course

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Purpose: To define the proteomic-changes which mediate the activity of CHIP to maintain 'health and wellness' during aging. There is compelling evidence that the E3-ubiquitin ligase CHIP supports healthy aging and wellbeing through-out the life course in both mammals and nematodes1. Inactivating mutations or KO mouse models for CHIP produce rapidly aging animals which also exhibit cognitive decline2, whereas in human's loss of normal CHIP function is causative for ataxia with cognitive impairment and/or dementia. CHIP was first studied as a component of the protein quality control network through its ability to bind to Hsp/c70, a core member of the molecular chaperone machinery. In this role, CHIP cooperates with the molecular chaperones to ubiquitinate misfolded, mutated or aggregated proteins signalling their degradation. The Ball group and others have defined a non-canonical role for CHIP as a chaperone-independent E3-ligase that specifically regulates a small cohort of native folded proteins involved in processes that are central to organismal health and aging including interferon signalling3 and insulin regulated pathways1.The non-canonical function of CHIP supports healthy aging at the level of the whole organism and plays a vital role in neuronal protection. Whereas the role of CHIP as part of the chaperone machinery aims to combat the development of toxic intermediates and protein aggregates. The dual functions of CHIP therefore make it an attractive target for therapeutic intervention as it offers the prospect of abrogating the early events in toxic protein genesis that is associated with aging and cognitive decline whilst at the same time promoting healthy aging. However, as yet we do not have a comprehensive view of the processes that mediate CHIP-dependent healthy aging in young cells and animals and how these pathways are suppressed or activated through-out the life course.The proposed state-of-the-art PhD project will exploit gene-editing technology to generate isogenic cell and C. elegans models which will be analysed using broad spectrum proteomic-techniques including label free data-independent mass-spectrometry (SWATH-MS). A major component of this cross-discipline project will be training in bioinformatics and its application to the development of bespoke reference libraries, proteomic data analysis and pathway mapping. The aim is to identify CHIP regulated pathways and how they change through-out the life course of cells and whole organisms. More specifically, the project will involve: (i) Generating bespoke reference spectral libraries (using MS and RNA-seq approaches) for peptide identification from neuronal stem cells (NSC) and C. elegans, models; (ii) the use of gene-editing technology to generate isogenic C. elegans and NSC models; (iii) SWATH-MS analysis complemented by RNA-seq, and (iv) genetic add-back of WT and mutant forms of CHIP which affect healthy aging and/or longevity. [1] Tawo, R., Pokrzywa, W., Kevei, E., Akyuz, M. E., Balaji, V., Adrian, S., Hohfeld, J., and Hoppe, T. (2017) The Ubiquitin Ligase CHIP Integrates Proteostasis and Aging by Regulation of Insulin Receptor Turnover, Cell 169, 470-482 e413.[2] Shi, C. H., Rubel, C., Soss, S. E., Sanchez-Hodge, R., Zhang, S., Madrigal, S. C., Ravi, S., McDonough, H., Page, R. C., Chazin, W. J., Patterson, C., Mao, C. Y., Willis, M. S., Luo, H. Y., Li, Y. S., Stevens, D. A., Tang, M. B., Du, P., Wang, Y. H., Hu, Z. W., Xu, Y. M., and Schisler, J. C. (2018) Disrupted structure and aberrant function of CHIP mediates the loss of motor and cognitive function in preclinical models of SCAR16, PLoS Genet 14, e1007664.[3] Narayan, V., Pion, E., Landre, V., Muller, P., and Ball, K. L. (2011) Docking-dependent ubiquitination of the interferon regulatory factor-1 tumor suppressor protein by the ubiquitin ligase CHIP, J Biol Chem 286, 607-619.