MCJ is a mitochondrial inner membrane protein identified as a natural inhibitor of respiratory chain Complex I. The induction of experimental colitis in MCJ-deficient mice leads to the upregulation of Timp3 expression resulting in the inhibition of TACE activity that likely inhibits Tnf and Tnfr1 shedding from the cell membrane in the colon. The gene discussed is IMMT; the disease is colitis.