LIM and SH3 protein 2 (Lasp2) is a novel pregnane X receptor target gene in mouse liver

LIM and Src homology 3 (SH3) protein 2 (LASP2) is a small focal adhesion protein first identified as a splice variant of the nebulette gene (Nebl). As the newest member of the nebulin protein family, the regulation and function of LASP2 remain largely unknown. Our previous RNA-sequencing results identified Nebl as one of the most highly induced genes in the mouse liver in response to the activation of pregnane X receptor (PXR). In this study, we investigated this phenomenon further and show that PXR induces Lasp2 instead of Nebl, which partially use the same exons. Lasp2 was found to be induced in response to PXR ligand pregnenolone 16α-carbonitrile (PCN) treatment in mouse liver in vivo both after 4-day treatment and after long-term, 28-day treatment and in both male and female mice. Interestingly, the Lasp2 induction was more efficient in high-fat diet-fed mice (103-fold after 4-day PCN treatment) than in the normal chow-fed mice (32-fold after 4-day PCN treatment). Lasp2 induction was abolished in PXR knockout mice but could be rescued by re-expression of PXR, indicating that Lasp2 induction is PXR mediated. In mouse primary hepatocytes cycloheximide did not inhibit Lasp2 induction by PCN and a PXR binding site could be recognized upstream of the mouse Lasp2 gene suggesting direct regulation of Lasp2 by PXR. In human 3D hepatocytes, rifampicin induced only a modest increase in LASP2 expression. This study shows for the first time that PXR activation strongly induces Lasp2 expression in mouse liver and establishes Lasp2 as a novel PXR target gene. SIGNIFICANCE STATEMENT: RNA-sequencing results have previously identified nebulette (Nebl) to be efficiently induced by pregnane X receptor activating compounds. This study shows that instead of Nebl, LIM and Src homology 3 (SH3) protein 2 (Lasp2) coding for a small focal adhesion protein and partly sharing exons with the Nebl gene is a novel target of pregnane X receptor in mouse liver.