Faithful epigenetic and transcriptional regulation of a transgenic human Th2 cytokine gene locus in the murine nuclear environment (51.1)

Abstract

Abstract Dysregulated production of the Th2 cytokines IL4 and IL13 is a hallmark of allergy and asthma. Th2 cytokine gene locus regulation has been extensively studied in mice, much less in humans. We have generated mice carrying a 160 kb BAC transgene (BAC5) that encompasses human RAD50, IL13 and IL4 and includes all the elements known to be required for faithful regulation of mouse Th2 cytokine locus. BAC5 transgenic mice appeared normal, were born at the expected Mendelian ratio, and carried 1-15 intact copies of BAC5. In vitro polarized mouse transgenic CD4 Th2, but not Th1 cells expressed human IL13 and IL4, demonstrating tissue-specific regulation of human Th2 cytokines. Murine CD4 T cells expressed physiologic levels of human IL13 and IL4, particularly in a house dust mite immunization model. Human IL13 expression was transgene copy number-dependent, suggesting BAC5 includes the human Th2 locus control region. Notably, DNA methylation patterns at multiple DNase I hypersensitive sites in the Th2 locus of human CD4 T cells were highly comparable if not identical in transgenic CD4 T cells of equivalent differentiation stages. Our results support the notion that in homologous tissues, genetic sequence is largely responsible for directing transcriptional programs and chromatin modifications even in a heterologous nuclear environment. Moreover, our findings suggest BAC5 transgenic mice are a powerful tool to study human Th2 cytokine gene regulation and Th2-dependent events in vivo.