Abstract / Summary
All-trans-retinal (atRAL) is a photoreactive aldehyde generated during visual pigment regeneration, and impaired atRAL clearance contributes to oxidative stress and retinal degeneration. Retinol dehydrogenase 12 (RDH12) reduces atRAL to all-trans-retinol, yet the temporal mechanisms linking its upstream enzymatic activity to downstream cellular stress adaptations remain poorly defined. Here, we utilized stable RDH12-expressing HEK293T cells to match proteomic and lipidomic profiles and performed cell viability assays to map the transition from acute atRAL stress to cellular recovery. RDH12 expression increased cellular tolerance to retinaldehyde-induced cytotoxicity. Acute atRAL exposure engaged the supply arm of the KEAP1-NRF2 program with increased HMOX1, SLC7A11, GCLC, MGST2, and MGST3, while the terminal glutathione peroxidase arm declined. Acute exposure was accompanied by membrane remodeling, indicated by increased glycerophospholipid enzyme abundance and increased stress-signaling ceramides and lysophosphatidylcholines. Concurrently, acute stress induced upregulation of the transferrin receptor (TFRC) and SLC11A2, which influence intracellular iron flux and enable Fenton chemistry that can lead to oxidative stress. During recovery, RDH12-expressing cells exhibited a distinct post-atRAL molecular state characterized by increased abundance of phosphatidylcholines (PCs) and ether-linked PCs, and proteome changes associated with cytoskeletal organization and antioxidant processes. Furthermore, we performed a pharmacological rescue with Ferrostatin-1, which indicated that atRAL-induced cytotoxicity in RDH12-expressing cells is dependent, in part, on lipid radical propagation and lipid peroxidation, supporting ferroptosis-regulated cell death. Collectively, the multiomics and biological findings establish a novel temporal sequence for retinaldehyde toxicity, showing that RDH12 is a critical component of upstream metabolic defense for acute aldehyde clearance, late-stage lipid detoxification, and adaptive membrane lipid homeostasis.