MPV17L is a mitochondrial protein that functions as an atypical phosphodiesterase (PDE) regulating cyclic nucleotide signaling and mitochondrial homeostasis. Despite lacking conserved PDE catalytic motifs, MPV17L exhibits PDE activity and modulates cAMP/PKA signaling in the mitochondrial matrix 1. The protein protects mitochondrial integrity by maintaining mtDNA stability through preservation of mitochondrial transcription factor A (TFAM) and base excision repair enzymes 2, and interacts with the HtrA2 protease to suppress mitochondrial superoxide generation and prevent apoptosis 3. MPV17L participates in reactive oxygen species metabolism by regulating antioxidant enzyme expression. In genetic models, MPV17L deficiency leads to β-cell hyperplasia and improved glucose tolerance via activation of Wnt and TGF-β signaling pathways 4. MPV17L variants have been associated with maturity-onset diabetes of the young and familial hyperinsulinemic hypoglycemia, and recent evidence links altered MPV17L expression to diabetic kidney disease progression 5 and lung adenocarcinoma prognosis 6. Epigenetic silencing of MPV17L under oxidative stress contributes to kidney fibrosis and renal injury 7, suggesting MPV17L represents a potential therapeutic target for metabolic and renal complications.