FUNDC1 Attenuates UVA-Induced Skin Photoaging by Regulating Mitophagy and P53 Stability.

Skin photoaging resulting from chronic ultraviolet A (UVA) exposure is closely associated with mitochondrial dysfunction and impaired cellular homeostasis. Mitophagy is an important mitochondrial quality control process, but the role of FUNDC1-associated mitophagy-related activity in skin photoaging remains incompletely understood. Here, we investigated the function and regulatory mechanisms of FUNDC1 in UVA-induced photoaging models. FUNDC1 expression was reduced in UVA-exposed human dermal fibroblasts (HDFs) and in photoaged mouse skin. FUNDC1 knockdown aggravated photoaging-associated phenotypes, mitochondrial dysfunction, and altered autophagy/mitophagy-related activity, whereas FUNDC1 overexpression attenuated these changes in vitro and in vivo. Pharmacological modulation further showed that Rapa partially counteracted FUNDC1 knockdown-associated effects, while Mdivi-1 weakened the protective effects associated with FUNDC1 overexpression, supporting the involvement of mitophagy-related mitochondrial quality control. Mechanistically, miR-137-3p was upregulated during UVA-induced photoaging and negatively regulated FUNDC1 expression through the predicted FUNDC1 3'UTR binding site. In addition, FUNDC1 was concerned with proteasome-dependent regulation of P53 protein stability. BAZ1B was identified as a candidate P53-associated ubiquitination regulator that participated in FUNDC1-associated regulation of P53 ubiquitination and stability. LC-MS/MS analysis combined with site-directed mutagenesis further manifested that P53 K292 was a major ubiquitination site involved in BAZ1B-associated regulation of P53 stability. In vivo, BAZ1B knockdown attenuated FUNDC1-associated protection against UVA-induced skin photoaging and reduced P53 ubiquitination. Collectively, these findings indicate that FUNDC1 can attenuate UVA-induced skin photoaging by preserving mitophagy-related mitochondrial homeostasis and modulating BAZ1B-associated P53 stability, with miR-137-3p acting as an upstream negative regulator of FUNDC1.