The goal of this project is to understand how protein quality control mechanisms in adult stem cells and theirprogenyareregulatedduringaging,withtheobjectivetorestorethefunctionalityofoldcells.Preservation of a pristine proteome is emerging as a critical mechanism for maintaining cellular function throughout life. Disruption in the machinery that maintains protein quality control leads to protein aggregation diseases and accelerated aging in invertebrate models. However, how cell types with different roles regulate protein homeostasisduringlongperiodsoftimeremainsunexplored,particularlyinmammals.Theadultbrainoffersa uniqueparadigmforunderstandingproteinqualitycontrolmechanismsincelltypeswithdifferentfunctions.It containsreservoirsofquiescentneuralstemcells(NSCs)thatcanactivateandinturngeneratedifferentiated cellswithspecializedfunction?neurons,astrocytes,andoligodendrocytes.Duringaging,theabilityofNSCsto exitquiescenceandtheirabilitytoproducenewneuronsbothdeclinedramaticallyyetthisdeteriorationisnot inexorableandcanbereversedbyenvironmentalinterventions,includingdiet.However,themechanismsthat canregulateNSCfunctionarelargelyunknown. We recently embarked on a systematic characterization of protein aggregates and proteostasis mechanisms in young NSCs and their progeny. Excitingly, we find that quiescent NSCs contain large protein aggregatesthatarepresentundegradedinlargelysosomes.Nutrientdeprivationcanclearproteinaggregates and enhance their ability to activate, a process that is dramatically affected by aging. Interestingly, our RNA- seq profiling from young and also mice reveal that quiescent NSCs from old mice exhibit a large degree of transcriptome-wide change with age. The central hypothesis of this Project is that the protein quality control mechanisms differ in cell types with distinct functions, which could underlie their different degree of deterioration with age and could be used for specifically ameliorating old cells. To test this idea, we propose thefollowingexperiments: 1. To understand how protein aggregates and protein quality control mechanisms are influenced by increasingageandbyrejuvenatingstrategies 2. To specifically modulate proteostasis mechanisms to ameliorate function in old NSCs and their differentiatedprogeny 3. To determine the composition of protein aggregates and generate new aggregate reporters in NSCs andtheirprogeny CompletionoftheseAimswillprovideuniquemechanisticinsightsintotheregulationofproteinaggregates and their alteration during aging in regenerative cells and their differentiated progeny. This study should also provide fundamental understanding of how protein quality control is mechanistically regulated in different cell types.Thisknowledgeshouldpavethewayforbuildingnewmethodsfor?rejuvenation?ofoldcellsandrestore protein aggregates, which will be a critical step for improving tissue function during aging and age-related disease.

Public Health Relevance

Astheorganismages,adultneuralstemcells(NSCs)nolongerproducenewneurons. Adult NSCs have been found to be important for aspects of learning and memory, raising the intriguing possibility that reactivating the NSC pool may help preserve or enhancecognitivefunctionwithadvancingage.Uncoveringthemechanismsunderlying the adult NSC maintenance and rejuvenation should give important insights into the factorsthatcontrolregenerationinthenormalagingnervoussystemaswellasinage- relatedneurodegenerativediseases.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG056290-04
Application #
9905325
Study Section
Cellular Mechanisms in Aging and Development Study Section (CMAD)
Program Officer
Wise, Bradley C
Project Start
2017-09-15
Project End
2022-03-31
Budget Start
2020-04-01
Budget End
2021-03-31
Support Year
4
Fiscal Year
2020
Total Cost
Indirect Cost
Name
Stanford University
Department
Genetics
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Dulken, Ben W; Leeman, Dena S; Boutet, St├ęphane C et al. (2017) Single-Cell Transcriptomic Analysis Defines Heterogeneity and Transcriptional Dynamics in the Adult Neural Stem Cell Lineage. Cell Rep 18:777-790
Shen, Koning; Calamini, Barbara; Fauerbach, Jonathan A et al. (2016) Control of the structural landscape and neuronal proteotoxicity of mutant Huntingtin by domains flanking the polyQ tract. Elife 5: