Roles And Mechanism Of RhoGDI2 In The Regulation Of T Lymphocyte Proliferation And Immunological Effect

The immune system is an important barrier of organisms,escorting our life and health all the time.T lymphocytes are one of the most important immune effector cells in the human body.They can kill the specific pathogens and produce immune protection.However,when it is dysfunctional,it can cause various diseases such as autoimmune diseases and cancer.Rho GTPases are a group of conserved guanylate binding proteins that act as molecular switches that control numerous signaling pathways in cells.It plays an important role in many life activities such as cytoskeleton reorganization,cell proliferation and migration,gene transcription.Rho GTPases are mainly regulated by guanine nucleotide exchange factors(GEFs),GTPase-activating proteins(GAPs)and Rho GDP-dissociation inhibitors(RhoGDIs).Among them,RhoGDIs are the most powerful and complex ones,and it is the key to maintaining the stable existence of the Rho family protein in cells.Only three types have been discovered so far,namely RhoGDI1,RhoGDI2 and RhoGDI3.RhoGDI2 is the only one of the RhoGDIs family that is significantly highly expressed in hematopoietic lymphoid tissues.Studies have shown that it can regulate the survival,activation and reactivity of lymphocytes.However,the research on the role,target and physiological function of RhoGDI2 in lymphocyte biology is far from enough,and we need to conduct more extensive and in-depth exploration.In this study,two classical T lymphocyte lines,HSB-2 and Jurkat cells,were used as experimental materials.The techniques of CCK-8,Western Blot,RT-PCR,GST-pull down,IP,etc.were used to explore the role and mechanism of RhoGDI2 in T lymphocytes.The main process was as follows: firstly,we explored the role of RhoGDI2 deletion in the normal immunization of T lymphocytes.The results of CCK-8 and Real time PCR showed that RhoGDI2 has a regulatory effect on the proliferation and immune effects of T lymphocytes;Meanwhile the stimulation of PMA(phorbol-12-myristate-13-acetate)combined with ionomycin caused RhoGDI2 serine phosphorylation.The results of bioinformatic analysis and molecular biology experiments showed that Ser31 of RhoGDI2 is an important serine phosphorylation site.Then,we explore whether the RhoGDI2 phosphorylation affects the proliferation and immunological effect of T lymphocytes by regulating Rho GTPases.In vitro and in vivo studies have shown that phosphorylation of RhoGDI2 Ser31 can reduce its binding ability to Rho GTPases.Finally,through structural analysis and truncated protein experiments,it is deduced that the decrease in binding affinity is most likely due to the destruction of chemical bonds between amino acids caused by phosphorylation.Eventually it leads to a decrease in the function of T lymphocytes.This study clarify the function,effector and mechanism of RhoGDI2 in T lymphocytes which could contribute to establish new therapeutic targets for related immune diseases caused by abnormal proliferation of T lymphocytes or abnormal effects of immunological response and take a more targeted treatment to control the deterioration of related diseases,providing theoretical support for clinical treatment.