Calcium/calmodulin-dependent protein kinase IV suppresses IL-2 production and regulatory T cell activity in lupus.

The activity of calcium/calmodulin-dependent protein kinase IV (CaMK4) is increased in T cells from patients with systemic lupus erythematosus (SLE) and has been shown to reduce IL-2 production by promoting the effect of the transcriptional repressor cAMP responsive element modulator-α on the IL2 promoter. In this article, we demonstrate that T cells from MRL/lpr mice display increased levels of CaMK4 in the nucleus, and that genetic deletion of Camk4 results in improved survival. We demonstrate that absence of CaMK4 restores IL-2 production, curbs increased T cell activation, and augments the number and activity of regulatory T cells. Analogously, silencing of CaMK4 in T cells from patients with SLE increases the expression of FoxP3 on stimulation in the presence of TGF-β. Our results demonstrate the importance of the serine/threonine kinase CaMK4 in the generation and function of regulatory T cells in patients with SLE and lupus-prone mice, and its potential to serve as a therapeutic target.