Protective role of DDIT4-mediated autophagy in dermal papilla cells after oxidative stress injury

To explore the protective role of DNA damage induced transcription factor 4 (DDIT4) in oxidative stress injury in dermal papilla cells and its underlying mechanisms.

Dermal papilla cells were exposed to UVA and H₂O₂ to establish cellular model of oxidative stress. CCK-8 assay was used to detect cell viability under different treatment conditions, and the production of intracellular reactive oxygen species (ROS) was detected using 2′, 7′-dichlorofluorescein diacetate (DCFH-DA). Autophagic vesicles were observed with electron microscopy. Western blotting was employed to measure the expression of DDIT4 and autophagy-related molecules, including microtubule-associated protein 1 light chain 3 (LC3), ubiquitin-binding protein (P62), mammalian target of rapamycin (mTOR), and p-mTOR.

UVA and H₂O₂ resulted in more production of ROS (P<0.05) and decreased viability of dermal papilla cells (P<0.05). DDIT4 expression was increased in dermal papilla cells under oxidative stress (P<0.05), and the antioxidant N-acetyl-L-cysteine (NAC) could effectively inhibit this effect (P<0.05). After treatment with UVA or H₂O₂, cell autophagy was enhanced in dermal papilla cells, characterized by an increase in the number of autophagosomes and an increased LC3Ⅱ/Ⅰ ratio (P<0.05), a decrease in P62 expression (P<0.05), and 3-methyladenine (3-MA) blocking autophagy led to further reduced cell viability (P<0.05) and increased intracellular ROS production (P<0.05). Conversely, rapamycin (RAPA) increased autophagy level and improved the viability of dermal papilla cells under oxidative conditions (P<0.05), and reduced the generation of intracellular ROS (P<0.05). Additionally, down-regulation of DDIT4 weakened autophagy in dermal papilla cells under oxidative stress, reduced LC3Ⅱ/Ⅰ (P<0.05), increased p-mTOR/mTOR and P62 (P<0.05), inhibited cell viability (P<0.05), and enhanced intracellular ROS production (P<0.05).

DDIT4 may alleviate oxidative stress injury in dermal papilla cells through autophagy.