Arginine methylation controls the strength of γc-family cytokine signaling in T cell maintenance.

The methylation of arginine residues in proteins is a post-translational modification that contributes to a wide range of biological processes. Many cytokines involved in T cell development and activation utilize the common cytokine receptor γ-chain (γc) and the kinase JAK3 for signal transduction, but the regulatory mechanism that underlies the expression of these factors remains unclear. Here we found that the arginine methyltransferase PRMT5 was essential for the maintenance of invariant natural killer T cells (iNKT cells), CD4+ T cells and CD8+ T cells. T cell-specific deletion of Prmt5 led to a marked reduction in signaling via γc-family cytokines and a substantial loss of thymic iNKT cells, as well as a decreased number of peripheral CD4+ T cells and CD8+ T cells. PRMT5 induced the symmetric dimethylation of Sm proteins that promoted the splicing of pre-mRNA encoding γc and JAK3, and this critically contributed to the expression of γc and JAK3. Thus, arginine methylation regulates strength of signaling via γc-family cytokines by facilitating the expression of signal-transducing components.

Selective fluorescence detection of small-molecule-binding proteins by using a dual photoaffinity labeling system.

PHOTO OPPORTUNITY: We have developed a dual photoaffinity labeling system in which an active and an inactive probe bearing orthogonal detection groups are co-reacted in a single photoreaction. The approach allowed selective fluorescent detection of a model binding protein in cell lysate by either 1D or 2D electrophoresis.

Active/inactive dual-probe system for selective photoaffinity labeling of small molecule-binding proteins.

Two are better than one: A new approach to selective photoaffinity labeling is described in which a bioactive probe is used in combination with its inactive analog as a scavenger of nonspecific proteins.