RUBCN (rubicon autophagy regulator) is a negative regulator of autophagosome maturation that plays dual roles in innate immunity. During bacterial infection, RUBCN promotes antimicrobial responses by stabilizing the CYBA:CYBB NADPH oxidase complex and increasing its association with TLR2, thereby enhancing ROS production and inflammatory cytokine release 1. Conversely, during fungal or viral infection, RUBCN negatively regulates pro-inflammatory cytokine production by sequestering CARD9 from signaling complexes 2. RUBCN functions mechanistically through interactions with key autophagy regulators including BECN1, PIK3C3/VPS34, and UVRAG 3. Recent evidence reveals that RUBCN lactylation at lysine 33 regulates LC3-associated phagocytosis and bacterial defense, with lactate metabolism modulating this process 4. RUBCN deficiency in hepatocytes impairs autophagy flux and promotes hepatic lipid accumulation, highlighting its pathogenic role in nonalcoholic fatty liver disease 5. In kidney proximal tubular epithelial cells, RUBCN deficiency paradoxically increases autophagic flux while causing metabolic syndrome features 6. RUBCN is associated with spinocerebellar ataxia type 15, an autosomal recessive disorder 7. Functionally, RUBCN negatively regulates autophagosome-lysosome fusion and phosphatidylinositol 3-kinase signaling, positioning it as a critical checkpoint in autophagy and immune responses.