Targeting Specific Kinase Substrates Rescues Increased Colitis Severity Induced by the Crohn’s Disease-Linked LRRK2-N2081D Variant

Abstract

AbstractLRRK2 contains a kinase domain where both the N2081D Crohn’s disease (CD) risk and the G2019S Parkinson’s disease (PD)-pathogenic variants are located. The mechanisms by which the N2081D variant increase CD risk, and how these adjacent mutations result in distinct diseases, remain unclear. To investigate the pathophysiology of the CD-linked LRRK2 N2081D variant, we generated a knock-in (KI) mouse model and compared its effects to those of the LRRK2-G2019S mutation. We find thatLrrk2N2081DKI mice demonstrate heightened sensitivity to induced colitis, resulting in more severe inflammation and intestinal damage thanLrrk2G2019SKI and wild-type mice. Analysis of Colon tissue revealed distinct mutation-dependent LRRK2 RAB substrate phosphorylation, with significantly elevated phosphorylated RAB10 levels inLrrk2N2081Dmice. In cells, we demonstrate that the N2081D mutation activates LRRK2 through a mechanism distinct from that of LRRK2-G2019S. We further find that proinflammatory stimulation enhances LRRK2 kinase activity, leading to mutation-dependent differences in RAB phosphorylation and inflammatory responses in dendritic cells. Finally, we show that genetic knockout ofRab12, but not pharmacological LRRK2 kinase inhibition, significantly reduced colitis severity inLrrk2N2081Dmice. Our study characterizes the pathogenic mechanisms of LRRK2-linked CD, highlights important structural and functional differences between disease-associated LRRK2 variants, and suggests RAB proteins as promising therapeutic targets for modulating LRRK2 activity in CD treatment.