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Hyperglycemic conditions may promote senescence & DNA damage in TIMELESS-depleted human cardiac fibroblasts
Thesis

Hyperglycemic conditions may promote senescence & DNA damage in TIMELESS-depleted human cardiac fibroblasts

Sahara Cassandra DeAngelis
Master of Science (M.S.), Drexel University
Apr 2024
DOI:
https://doi.org/10.17918/00010482
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DeAngelis_Sahara_20241.12 MB
PDF Embargoed Access, Embargo ends: 30 Jun 2026

Abstract

Fibroblasts Hyperglycemia
Increased senescence is a major hallmark of aging and is induced by DNA damage. Senescent cells have undergone irreversible cell cycle arrest and cease to proliferate. These cells have senescence-associated secretory phenotypes (SASPs) that lead to secretion of proinflammatory compounds that promote tumor development. Recent studies propose that over-nutrition leading to chronic hyperglycemia gives rise to premature senescence; however, the molecular basis of this mechanism remains elusive. Our previous studies demonstrated that the TIMELESS (TIM) protein plays a critical role in preventing replication stress, DNA damage, and telomere shortening. We hypothesized that TIM is required for preventing DNA damage and cellular senescence under hyperglycemic conditions. To test this hypothesis, we depleted TIM in human cardiac fibroblasts (HCFs), a well-established model for studying nutrient sensing and aging regulation. We found that TIM-depleted HCFs have elevated levels of the senescence marker β-galactosidase when cultured under high glucose concentrations mimicking hyperglycemic conditions. Similarly, Western Blot analyses revealed that senescence biomarkers such as p16 and p27 were elevated upon depleting TIM in HG conditions. We also observed a reduced level of Lamin-B1, which is often seen in senescence cells. Finally, immunofluorescence microscopy analysis indicated that TIM-depleted cells showed considerably elevated levels of γ-H2AX, a general DNA damage marker. These data suggest that TIM plays a critical role in preventing DNA damage and senescence under hyperglycemic conditions.

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