LRBA promotes drug-induced liver injury and MASLD by scaffolding MAPK activation
LPS-responsive beige-like anchor protein (LRBA) regulates vesicular trafficking and receptor recycling, and its deficiency results in immunodeficiency characterized by hypogammaglobulinemia and autoimmune syndrome. However, its role in liver pathophysiology remains unclear. Here, we reveal a previously unrecognized function of LRBA as a critical intracellular scaffold for mitogen-activated protein kinase (MAPK) activation that promotes liver injury. Lrba-/-mice exhibit reduced acetaminophen (APAP)-induced hepatic necrosis through the suppression of JNK activation. In a model of metabolic dysfunction-associated steatotic liver disease (MASLD) induced by a high-fat, high-cholesterol (HFHC) diet, Lrba deficiency reduces hepatic inflammation, fibrosis, and Kupffer cell activation. Mechanistically, LRBA homodimers directly interact with specific mitogen-activated protein kinase kinase kinases (MAP3Ks), including transforming growth factor-{beta}-activated kinase 1 (TAK1) and mixed-lineage kinase 3 (MLK3), to facilitate their activation. LRBA, which is primarily expressed in hepatocytes under physiological conditions, is upregulated in non-parenchymal cells such as Kupffer cells and cholangiocytes in both HFHC diet-fed mice and patients with MASLD and cirrhosis, linking its scaffolding function to pathological inflammation. Thus, LRBA promotes liver disease progression by amplifying inflammatory signaling.