Host factor RBMX2 promotes epithelial cell apoptosis by downregulating APAF-1’s Retention Intron after Mycobacterium bovis infection

The <i>Mycobacterium tuberculosis</i> variant bovis (<i>M. bovis</i>) is a highly pathogenic environmental microorganism that causes bovine tuberculosis (bTB), a significant zoonotic disease. Currently, "test and culling" is the primary measure for controlling bTB, but it has been proven to be inadequate in animals due to their high susceptibility to the pathogen. Selective breeding for increased host resistance to bTB to reduce its prevalence is feasible. In this study, we found a vital host-dependent factor, <i>RBMX2</i>, that can potentially promote <i>M. bovis</i> infection. By knocking <i>RBMX2</i> out, we investigated its function during <i>M. bovis</i> infection. Through transcriptome sequencing and alternative splicing transcriptome sequencing, we concluded that after <i>M. bovis</i> infection, embryo bovine lung (EBL) cells were significantly enriched in RNA splicing associated with apoptosis compared with wild-type EBL cells. Through protein/molecular docking, molecular dynamics simulations, and real-time quantitative PCR, we demonstrated that <i>RBMX2</i> promotes the apoptosis of epithelial cells by upregulating and binding to apoptotic peptidase activating factor 1 (APAF-1), resulting in the alternative splicing of APAF-1 as a retention intron. To our knowledge, this is the first report of <i>M. bovis</i> affecting host epithelial cell apoptosis by hijacking <i>RBMX2</i> to promote the intron splicing of downstream APAF-1. These findings may represent a significant contribution to the development of novel TB prevention and control strategies.