Transcriptional profile of Smad4-deficient CTLs is similar to TRM

Transforming growth factor β (TGFβ) is a morphogenic protein that augments antiviral immunity by altering the functional properties of pathogen-specific memory CD8 T cells. During infection, TGFβ inhibits formation of effector (TEFF) and circulating memory CD8 T cells, while encouraging tissue-resident memory CD8 T cells (TRM) to settle in peripheral tissues. SMAD proteins are signaling intermediates that are used by members of the TGF cytokine family to modify gene expression. Using RNA-sequencing we determined that SMAD4 altered the transcriptional profile of antiviral CTLs during respiratory infection. Our data show that SMAD4 and TGFβ use alternate signaling pathways to cooperatively regulate a collection of genes that determine whether pathogen-specific memory CD8 T cells localize in peripheral or lymphoid tissues. During infection, SMAD4 acts independently of TGF to inhibit TRM development, while inducing genes that support formation of circulating memory CD8 T cells. The genes that are modulated by SMAD4 include several homing receptors (CD103, KLRG1 and CD62L) and transcription factors (Hobit and EOMES) that support memory formation. mRNA expression analysis of 2 samples: WT & Smad4 deficient Early Effector CD8 T cells. D6 X31 infection Early effector subset (KLRG1lo, CD127lo, CD103lo)