Tmem110 regulates the conformation of TRPML1 to maintain endolysosomal homeostasis and prevent mitochondrial DNA leakage and pathological self-DNA processing.

The mechanisms by which phagocytes handle large quantities of internalized organelles, such as mitochondria released during tissue injury, remain unclear. Here we show that the endoplasmic reticulum transmembrane regulator TMEM110 is a key determinant of disease severity in traumatic brain injury-associated multiple organ dysfunction. Loss of TMEM110 impairs the clearance of mitochondria aberrantly released into the circulation, leading to heightened autoimmune-mediated tissue injury and mortality. TMEM110 maintains lysosomal function by controlling the conformational transition of the lysosomal ion channel TRPML1 and generating localized calcium efflux sites, thereby preventing calcium overload, membrane disruption, and leakage of mitochondrial DNA into the cytosol. We further find that TMEM110 expression is restrained by the nucleic acid sensor STING under basal conditions, and that a naturally occurring interface mutation between TMEM110 and STING causes defective lysosomal DNA disposal and aberrant type I interferon activity. These findings identify a feedback pathway linking cytosolic DNA sensing to organelle homeostasis.