Yu Zheng

The crucial role of CD4 + and CD8 + T cells in shaping and controlling immune responses during immune disease and cancer development has been well established and used to achieve marked clinical benefits. CD3 + CD4 - CD8 - double-negative (DN) T cells, although constituting a rare subset of peripheral T cells, are gaining interest for their roles in inflammation, immune disease and cancer. Herein, we comprehensively review the origin, distribution and functions of this unique T cell subgroup. First, we focused on characterizing multifunctional DN T cells in various immune responses. DN regulatory T cells have the capacity to prevent graft-versus-host disease and have therapeutic value for autoimmune disease. T helper-like DN T cells protect against or promote inflammation and virus infection depending on the specific settings and promote certain autoimmune disease. Notably, we clarified the role of DN tumor-infiltrating lymphocytes and outlined the potential for malignant proliferation of DN T cells. Finally, we reviewed the recent advances in the applications of DN T cell-based therapy for cancer. In conclusion, a better understanding of the heterogeneity and functions of DN T cells may help to develop DN T cells as a potential therapeutic tool for inflammation, immune disorders and cancer.

Histone modification is an important epigenetic regulation in higher plants adapting to environment changes including salt and drought stresses. In this report, we show that the Arabidopsis RPD3-type histone deacetylase HDA9 is involved in modulating plant responses to salt and drought stresses in Arabidopsis. Loss-of-function mutants of the gene displayed phenotypes (such as seedling root growth and seed germination) insensitive to NaCl and polyethylene glycol (PEG) treatments. HDA9 mutation led to up-regulation of many genes, among which those involved in response to water deprivation stress (GO: 0009414) were enriched. These genes were much more induced in the mutants than wild-type plants when treated with PEG and NaCl. In addition, we found that in the mutants, salt and drought stresses led to much higher levels of histone H3K9 acetylation at promoters of 14 genes randomly selected from those that respond to water-deprivation stress than in wild-type plants. Our study suggested that HDA9 might be a novel chromatin protein that negatively regulates plant sensitivity to salt and drought stresses by regulating histone acetylation levels of a large number of stress-responsive genes in Arabidopsis.