Paper Spotlight: Downregulated IGFBP5 Contributes to Replicative Senescence



April 21, 2022

Aging (Aging-US) published this research paper as the cover for Volume 14, Issue 7, entitled, "Downregulation of IGFBP5 contributes to replicative senescence via ERK2 activation in mouse embryonic fibroblasts" by researchers from the Department of Pharmacology, Sapporo Medical University School of Medicine, Sapporo, Japan. DOI - Corresponding author - Atsushi Kuno - Abstract Insulin-like growth factor (IGF)-binding proteins (IGFBPs) are secretory proteins that regulate IGF signaling. In this study, we investigated the role of IGFBP5 in replicative senescence in embryonic mouse fibroblasts (MEFs). During passages according to the 3T3 method, MEFs underwent senescence after the 5th passage (P5) based on cell growth arrest, an increase in the number of cells positive for senescence-associated β-galactosidase (SA-β-GAL) staining, and upregulation of p16 and p19. In P8 MEFs, IGFBP5 mRNA level was markedly reduced compared with that in P2 MEFs. Downregulation of IGFBP5 via siRNA in P2 MEFs increased the number of SA-β-GAL-positive cells, upregulated p16 and p19, and inhibited cell growth. Incubation of MEFs with IGFBP5 during serial passage increased the cumulative population doubling and decreased SA-β-GAL positivity compared with those in vehicle-treated cells. IGFBP5 knockdown in P2 MEFs increased phosphorylation levels of ERK1 and ERK2. Silencing of ERK2, but not that of ERK1, blocked the increase in the number of SA-β-GAL-positive cells in IGFBP5-knockdown cells. The reduction in the cell number and upregulation of p16 and p21 in IGFBP5-knockdown cells were attenuated by ERK2 knockdown. Our results suggest that downregulation of IGFBP5 during serial passage contributes to replicative senescence via ERK2 in MEFs. Sign up for free Altmetric alerts about this article - Keywords - aging, IGFBP5, replicative senescence, mouse embryonic fibroblasts, ERK2, ERK1 About Aging-US Launched in 2009, Aging-US publishes papers of general interest and biological significance in all fields of aging research and age-related diseases, including cancer—and now, with a special focus on COVID-19 vulnerability as an age-dependent syndrome. Topics in Aging-US go beyond traditional gerontology, including, but not limited to, cellular and molecular biology, human age-related diseases, pathology in model organisms, signal transduction pathways (e.g., p53, sirtuins, and PI-3K/AKT/mTOR, among others), and approaches to modulating these signaling pathways. Please visit our website at​​ and connect with us: SoundCloud - Facebook - Twitter - Instagram - YouTube -​ LinkedIn - Pinterest - Aging-US is published by Impact Journals, LLC:​​ Media Contact 18009220957 MEDIA@IMPACTJOURNALS.COM

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