We recently identified the hypoxic response transcription factor, HIF-1, as a novel modifier of longevity and healthspan in Caenorhabditis elegans. In a study published in the journal Science, we showed that stabilization of HIF-1 by inhibiting its proteasomal degradation under normoxic conditions increases life span through a mechanism that is genetically distinct from dietary restriction and reduced insulin-like signaling, a finding that has since been independently replicated by two groups. We also showed that growth of wild type animals under hypoxia, which is sufficient to stabilize and activate HIF-1, also increases life span. Following publication of our study, the Kapahi lab reported that loss of HIF-1 increases life span under their experimental conditions. We have since determined that stabilization of HIF-1 increases life span in a temperature- independent manner, while loss of HIF-1 increases life span in a temperature-dependent manner. Unlike life span extension from activation of HIF-1 in normoxia, life span extension from deletion of HIF-1 or hypoxia requires the FOXO-family transcription factor DAF-16. Here we propose to further define the mechanisms by which HIF-1 modulates longevity and healthspan in C. elegans, both as a pro- and anti-longevity factor.
In Specific Aim 1, we will (1) further define the experimental conditions under which deletion of HIF-1 can increase life span and determine whether healthspan is also extended under these conditions, (2) test the hypothesis that DAF-16 is activated by loss of HIF-1 or by hypoxia using chromatin immunoprecipitation to determine whether DAF-16 is localized to known or novel target genes, and (3) determine how DAF-16 becomes relocalized to the nucleus in response to loss of HIF-1 or hypoxia by using mass spectrometry to quantify known and novel post-translational modifications of DAF-16 in response to these interventions.
In specific Aim 2, we will (1) use RNAi knock-down mRNAs that are differentially expressed in response to stabilization of HIF-1 to identify the downstream targets of HIF-1 that are involved in life span and healthspan extension when HIF-1 is stabilized under normoxic conditions and (2) determine whether these genes play a role in modulating longevity in response to other known longevity pathways.
In specific Aim 3, we will determine which cell types are involved in modulating life span and healthspan extension from stabilization of HIF-1 under normoxic conditions by generating transgenic animals expressing either (1) the VHL-1 E3 ligase which targets HIF-1 for degradation or (2) a non-degradable form of HIF-1 under promoters with known cell- type specificities and quantifying the resulting effects on longevity and measures of healthspan. HIF-1 and the hypoxic response are highly conserved from nematodes to humans and have been implicated in human diseases, most notably a variety of cancers. Thus, a better understanding of the dual role that HIF-1 can play as a modifier of life span and healthspan in nematodes will lead to new hypotheses that can be directly tested in mammals, and is likely to be directly relevant to human health and age-related disease.

Public Health Relevance

The hypoxic response is an evolutionarily conserved cellular response to reduced oxygen availability that has been implicated in several human diseases, including a variety of cancers, and which we have recently shown to regulate both life span and healthspan in Caenorhabditis elegans. The goal of this proposal is to define the mechanistic details by which the hypoxic response modulates aging and age-related disease in C. elegans, in order to understand the basic mechanisms of aging and identify potential therapeutic targets for treating age- related diseases and extending healthspan in people.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
1R01AG038518-01
Application #
8020163
Study Section
Cellular Mechanisms in Aging and Development Study Section (CMAD)
Program Officer
Finkelstein, David B
Project Start
2011-04-01
Project End
2016-03-31
Budget Start
2011-04-01
Budget End
2012-03-31
Support Year
1
Fiscal Year
2011
Total Cost
$307,918
Indirect Cost
Name
University of Washington
Department
Pathology
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Rossner, Ryan; Kaeberlein, Matt; Leiser, Scott F (2017) Flavin-containing monooxygenases in aging and disease: Emerging roles for ancient enzymes. J Biol Chem 292:11138-11146
Bennett, Christopher F; Kwon, Jane J; Chen, Christine et al. (2017) Transaldolase inhibition impairs mitochondrial respiration and induces a starvation-like longevity response in Caenorhabditis elegans. PLoS Genet 13:e1006695
Mendenhall, Alexander; Crane, Matthew M; Leiser, Scott et al. (2017) Environmental Canalization of Life Span and Gene Expression in Caenorhabditis elegans. J Gerontol A Biol Sci Med Sci 72:1033-1037
Kapahi, Pankaj; Kaeberlein, Matt; Hansen, Malene (2017) Dietary restriction and lifespan: Lessons from invertebrate models. Ageing Res Rev 39:3-14
Miller, Hillary; Fletcher, Marissa; Primitivo, Melissa et al. (2017) Genetic interaction with temperature is an important determinant of nematode longevity. Aging Cell 16:1425-1429
Leiser, Scott F; Jafari, Gholamali; Primitivo, Melissa et al. (2016) Age-associated vulval integrity is an important marker of nematode healthspan. Age (Dordr) 38:419-431
Leiser, Scott F; Rossner, Ryan; Kaeberlein, Matt (2016) New insights into cell non-autonomous mechanisms of the C. elegans hypoxic response. Worm 5:e1176823
Leiser, Scott F; Miller, Hillary; Rossner, Ryan et al. (2015) Cell nonautonomous activation of flavin-containing monooxygenase promotes longevity and health span. Science 350:1375-1378
Jafari, Gholamali; Wasko, Brian M; Tonge, Ashley et al. (2015) Tether mutations that restore function and suppress pleiotropic phenotypes of the C. elegans isp-1(qm150) Rieske iron-sulfur protein. Proc Natl Acad Sci U S A 112:E6148-57
Bitto, Alessandro; Wang, Adrienne M; Bennett, Christopher F et al. (2015) Biochemical Genetic Pathways that Modulate Aging in Multiple Species. Cold Spring Harb Perspect Med 5:

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