Epigallocatechin-3-gallate (EGCG) up-regulates miR-15b expression thus attenuating store operated calcium entry (SOCE) into murine CD4+ T cells and human leukaemic T cell lymphoblasts

// Shaqiu Zhang 1,2,6,* , Tamer al-Maghout 2,6,* , Rosi Bissinger 2,6 , Ni Zeng 2,3,6 , Lisann Pelzl 2,6 , Madhuri S. Salker 2,4,6 , Anchun Cheng 1,** , Yogesh Singh 2,5,6,** and Florian Lang 2,6** 1 Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, P.R. China 2 Department of Internal Medicine III, Tubingen University, Gmelinstraβe, Tubingen, Germany 3 Department of Cleft Lip and Palate Surgery, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, P.R. China 4 Institute of Women’s Health, Tubingen University, Calwerstraβe, Tubingen, Germany 5 Institute of Medical Genetics and Applied Genomics, Tubingen University, Calwerstraβe, Tubingen, Germany 6 Institute of Physiology I, Tubingen University, Gmelinstraβe, Tubingen, Germany * Equal contributions thus sharing first authorship ** Equal contributions thus sharing last authorship Correspondence to: Anchun Cheng, email: // Yogesh Singh, email: // Florian Lang, email: // Keywords : Murine CD4 + T cells, human leukaemic T cell lymphoblasts, EGCG, SOCE, miR-15b, Immunology and Microbiology Section, Immune response, Immunity Received : January 10, 2017 Accepted : July 26, 2017 Published : August 08,2017 Abstract CD4 + T cells are key elements in immune responses and inflammation. Activation of T cell receptors in CD4 + T cells triggers cytosolic Ca 2+ release with subsequent store operated Ca 2+ entry (SOCE), which is accomplished by the pore forming Ca 2+ release activated Ca 2+ (CRAC) channel Orai1 and its regulator stromal cell-interaction molecule 2 (STIM2). Green tea polyphenol epigallocatechin-3-gallate (EGCG) acts as a potent anti-inflammatory and anti-oxidant agent for various types of cells including immune cells. However, how post-transcriptional gene regulators such as miRNAs are involved in the regulation of Ca 2+ influx into murine CD4 + T cells and human Jurkat T cells through EGCG is not defined. EGCG treatment of murine CD4 + T cells significantly down-regulated the expression of STIM2 and Orai1 both at mRNA and protein levels. Furthermore, EGCG significantly decreased SOCE in both murine and human T cells. EGCG treatment increased miRNA-15b (miR-15b) abundance in both murine and human T cells. Bioinformatics analysis reveals that miR-15b, which has a STIM2 binding site, is involved in the down-regulation of SOCE. Overexpression of miR-15b significantly decreased the mRNA and protein expression of STIM2 and Orai1 in murine T cells. Treatment of Jurkat T cells with 10 µM EGCG further decreased mTOR and PTEN protein levels. EGCG decreased mitochondrial membrane potential (MMP) in both human and murine T cells. In conclusion, the observations suggest that EGCG inhibits the Ca 2+ entry into murine and human T cells, an effect accomplished at least in part by up-regulation of miR-15b.