The Il17 and Il17f genes are encoded at the same chromosomal locus, separated only by ~43.9 kb in mice and are transcribed in opposite directions. Even though, these constraints could have suggested these genes were regulated in parallel by similar mechanisms, this does not hold true.
Dong and colleagues have identified a conserved noncoding sequence 2 (CNS2) that is sufficient and necessary for Il17 transcription but only participate in optimal Il17f gene transcription in CD4 Th17 cells.
In addition, this CNS2 appear to be less crucial in gd T cells. Indeed, while this CNS2 is not regulating the % of IL-17-producing gd T cells, it has an impact on the amount of IL-17 produced per gd T cells.
This paper is important, for it highlights further that the mechanisms for IL-17-production may differ in CD4 T cells and gd T cells. This, without doubt, paves the way for studying IL-17-production in these two T cell types side by side.