DNA-PKcs kinase activity stabilizes the transcription factor Egr1 in activated immune cells

Waldrip, Z. J.; Burdine, L.; Harrison, D. K.; Azevedo-Pouly, A. C.; Storey, A. J.; Moffett, O. G.; Mackintosh, S. G.; Burdine, M. S.

doi:10.1101/2021.06.04.446996

bioRxiv · 10.1101/2021.06.04.446996

DNA-PKcs kinase activity stabilizes the transcription factor Egr1 in activated immune cells

Waldrip, Z. J.·Burdine, L.·Harrison, D. K.·Azevedo-Pouly, A. C.·Storey, A. J.·Moffett, O. G.·Mackintosh, S. G.·Burdine, M. S.

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Abstract

DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is known primarily for its function in DNA double-stranded break repair and non-homologous end joining (NHEJ). However, DNA-PKcs also has a critical yet undefined role in immunity impacting both myeloid and lymphoid cell lineages spurring interest in targeting DNA-PKcs for therapeutic strategies in immune-related diseases. To gain insight into the function of DNA-PKcs within immune cells, we performed a quantitative phosphoproteomic screen in T cells to identify first order phosphorylation targets of DNA-PKcs. Results indicate that DNA-PKcs phosphorylates the transcription factor Egr1 (early growth response protein 1) at S301. Expression of Egr1 is induced early upon T cell activation and dictates T cell response by modulating expression of cytokines and key costimulatory molecules. Mutation of serine 301 to alanine via CRISPR-Cas9 resulted in increased proteasomal degradation of Egr1 and a decrease in Egr1-dependent transcription of IL2 (interleukin-2) in activated T cells. Our findings identify DNA-PKcs as a critical intermediary link between T cell activation and T cell fate and a novel phosphosite involved in regulating Egr1 activity.

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Waldrip, Z. J., Burdine, L., Harrison, D. K., Azevedo-Pouly, A. C., Storey, A. J., Moffett, O. G., Mackintosh, S. G., Burdine, M. S.. 2021-06-04. DNA-PKcs kinase activity stabilizes the transcription factor Egr1 in activated immune cells. https://doi.org/10.1101/2021.06.04.446996

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