T-2 toxin induces the expression of porcine CYP3A22 via the upregulation of the transcription factor, NF-Y.

BACKGROUND:T-2 toxin is one of the major pollutants in crops and feedstuffs. CYP3A22, one of hCYP3A4 homologs, detoxifies T-2 toxin in pigs. We investigated the mechanisms of expression activation of CYP3A22 under basal and induced conditions. METHODS:Based on MatInspector analysis, several mutations in the CYP3A22 promoter were assayed by dual luciferase reporter to identify the function of cis elements in the region. EMSA experiments were used to assess the binding of transcription factors to the cis elements. The mRNA and protein levels of CYP3A22 and the transcription factors were measured by RT-qPCR and Western blot. The enhancement of NF-Y binding to the CYP3A22 promoter was assayed by ChIP. RESULTS:As predicted, two cis DNA elements in the CYP3A22 promoter, a CCAAT box and GC box, were confirmed to be crucial in the activation of CYP3A22 transcription. These two DNA motifs recruited two transcription factors, NF-Y and Sp1, which are involved in the activation of the basal transcription of CYP3A22. More interestingly, CYP3A22 expression was induced in porcine primary hepatocytes by the treatment with 0.1μg/mL T-2 toxin. This induction of transcription by T-2 toxin was dominantly regulated by the binding of NF-Y to the CCAAT box, rather than GC box, which recruits Sp1 and functions only in the constitutive expression of CYP3A22. CONCLUSIONS:Our study reveals the regulatory mechanisms of both basal and inducible transactivation of CYP3A22 in pigs. In particular, we identified that the mechanism by which T-2 toxin induces CYP3A22 expression is mediated by the upregulation of NF-YA. GENERAL SIGNIFICANCE:Although porcine CYP3A22 is homologous to hCYP3A4, the regulation of basal and induced expression of CYP3A22 occurred via distinct mechanisms. This may account for the variety of CYP3A expression in animals and humans.

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