GATA3 Abundance Is a Critical Determinant of T Cell Receptor β Allelic Exclusion

ABSTRACT

Allelic exclusion describes the essential immunological process by which feedback repression of sequential DNA rearrangements ensures that only one autosome expresses a functional T or B cell receptor. In wild-type mammals, approximately 60% of cells have recombined the DNA of one T cell receptor β (TCRβ) V-to-DJ-joined allele in a functional configuration, while the second allele has recombined only the DJ sequences; the other 40% of cells have recombined the V to the DJ segments on both alleles, with only one of the two alleles predicting a functional TCRβ protein. Here we report that the transgenic overexpression of GATA3 leads predominantly to biallelic TCRβ gene (Tcrb) recombination. We also found that wild-type immature thymocytes can be separated into distinct populations based on intracellular GATA3 expression and that GATA3^LO cells had almost exclusively recombined only one Tcrb locus (that predicted a functional receptor sequence), while GATA3^HI cells had uniformly recombined both Tcrb alleles (one predicting a functional and the other predicting a nonfunctional rearrangement). These data show that GATA3 abundance regulates the recombination propensity at the Tcrb locus and provide new mechanistic insight into the historic immunological conundrum for how Tcrb allelic exclusion is mediated.

KEYWORDS:

• allelic exclusion
• T cell receptor beta locus
• GATA3
• monoallelic-to-biallelic switch

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ACKNOWLEDGMENTS

This work was supported by National Institutes of Health grants AI094642 (T.H. and J.D.E.), AI063058 (J.M.S.), AI091627 (I.M.), and NSF1452656 (Y.G.). The research was also supported in part by a University of Michigan Comprehensive Cancer Center support grant (P30 CA046592) that provides support for the Flow Cytometry and DNA Sequencing Core facilities at the University of Michigan.

We are grateful to Constantin Nelep for assistance using the CellCelector (ALS Automated Lab Solutions GmbH, Jena, Germany) to isolate single cells.

We declare that we have no competing financial interests.

C.-J.K. designed the study, performed experiments, analyzed the data, and wrote the manuscript. B.P. and Y.G. analyzed RNA-seq data. S.T. and K.Y. contributed GATA3 transgenic mouse lines and edited the manuscript. J.M.S. and I.M. designed the study and edited the manuscript. T.H. and J.D.E. designed the study, analyzed the data, and wrote the manuscript.