Telomerase inhibition causes premature senescence of fetal guinea pig muscle cells

Abstract

Premature senescence in low birth weight rodents is associated with later life metabolic disease, including the development of insulin resistance. Telomerase, a reverse transcriptase enzyme with telomeric and non-telomeric functions, is present at high levels during development to maintain and repair long telomere lengths and to protect cells from oxidative stress-induced growth arrest. Adverse In utero environments are often associated with increased reactive oxygen species (ROS), and ROS have been documented to impair/alter telomerase function. We postulate that telomerase protects cells against oxidative stress-induced damage, and its inhibition could lead to premature senescence. A primary cell line of fetal guinea pig muscle cells was differentiated under high (20%) and low (1-2%) oxygen concentrations and telomerase activity was pharmacologically inhibited using a synthetic tea catechin. Following 48 hours, ROS detection was conducted with MitoSOX, Mitotracker and 6-carboxy-2,7-dichlorodihydrofluorescein diacetate staining. Cells cultured at 20% O2 and treated with a telomerase activity inhibitor displayed reduced cell growth rates and increased levels of senescence markers, including p21 and p53. Telomeric DNA damage, measured by phosphorylated-{gamma}H2A.X staining at telomeres, was significantly increased in cells cultured at all oxygen concentrations with telomerase inhibition. Telomerase inhibition altered metabolic signaling (e.g. mTOR, p66Shc) and increased mitochondrial ROS levels. Telomerase may protect cells during development from adverse in utero environments that cause premature senescence.