Seongho Cha, Myeongwoo Jung, Hyosun Tak, Seungyeon Ryu, Sukyoung Han, Dongwoo Chae, Jiyoon Kim, Seung Min Jeong, Wook Kim, Eun Kyung Lee
Mitochondrial dysfunction, characterized by reduced mitophagy, excessive mitochondrial elongation, and elevated reactive oxygen species production, is a hallmark of cellular senescence. However, the molecular mechanisms linking impairment of redox balance to mitophagy suppression during senescence remain poorly understood. In this study, we identified TIA-1, an RNA-binding protein, as a positive regulator of FUNDC1 expression, a key receptor for ubiquitin-independent mitophagy. Sodium butyrate and ultraviolet-B irradiation triggered oxidative stress-associated senescence in HaCaT cells, leading to reduced TIA-1 expression, decreased FUNDC1 levels, impaired mitophagy flux, excessive mitochondrial elongation, and upregulation of senescence markers. Conversely, ectopic expression of TIA-1 restored FUNDC1 levels, enhanced mitophagy, improved mitochondrial function, and reduced senescence marker expression. Ribonucleoprotein immunoprecipitation assays confirmed that TIA-1 directly interacts with FUNDC1 mRNA, and subsequent analyses indicated that TIA-1 enhances FUNDC1 expression primarily through translational control. Together, these findings establish TIA-1 as a pivotal regulator of mitochondrial homeostasis during cellular stress, acting through FUNDC1 to sustain mitophagy and limit senescence. Targeting TIA-1 may offer new strategies to mitigate mitochondrial dysfunction and restore redox balance in aging and age-related diseases.