The Role And Mechanism Of ORP4L Regulation In PLCβ3 Translocation In T-cell Acute Lymphoblastic Leukemia(T-ALL) Cells

Acute lymphoblastic leukemia(Acute lymphoblastic leukemia,ALL)is a malignant tumor with abnormal proliferation of B or T cells originating from lymphocytes.Abnormal proliferation of the original cells can accumulate in the bone marrow and inhibit normal hematopoiesis,and can also invade the tissues outside the marrow,such as the meninges,lymph nodes,gonadal glands and liver.ORP4 L a member of the oxysterol binding protein related proteins family was detected in peripheral blood leucocytes in patients with early chronic myeloid leukemia,but not in normal peripheral blood leukocytes.This indicates that ORP4 L may be a potential marker for the proliferation of solid tumors,and some studies suggest that ORP4 L is associated with the proliferation of solid tumor cells.However,the role and detailed mechanism of ORP4 L in early chronic granulocytic leukocytes are not clear.In a previous study,we demonstrated that OSBP-related protein 4L(ORP4L)anchors CD3ε to Gαq/11 to control relocation and activation of PLCβ3(Phosphoric inositol phospholipase C).The underlying mechanism by which ORP4 L mediates PLCβ3 translocation is,however,still unknown.In this article,Immunofluorescence staining with anti-PLCβ3 showing nuclear localization of the protein in Jurkat T-cells.With the stimulate of anti-CD3ε we confirm that ORP4 L regulates PLCβ3 translocation from the nucleus to plasma.The Determination of Ran activity show that ORP4 L transport PLCβ3 from the nucleus of acute T lymphocytic leukemia cells by activating Ran.In the immunoprecipitation experiment of Jurkat T cells,the interaction between ORP4 L and membrane protein VAPA was determined,and the RNA interference method was used to inhibit the expression of VAPA or silence ORP4 Land knock out the FFAT(two phenylalanines in an acidic tract)structure of the wild type ORP4 L to investigate the relationship between PLCβ3migration and the complex formed by ORP4 L..Here we report that ORP4 L regulates PLCβ3translocation from the nucleus to plasma membrane in two steps:(1)ORP4L is required for the activation of Ran,a GTP-binding nuclear protein that binds to exportin1 and eventually results in the nuclear export of PLCβ3;(2)We further confirmed that ORP4 L interacts with the membrane receptor VAPA and this complex was enables the shift of PLCβ3 to the plasma membrane,indicating that PLCβ3 translocation occurs in a vesicle-dependent manner.This study offers mechanic insight into the role of ORP4 L roles in PLCβ3 redistribution via Ran activation and VAPA involvement,and suggests a model the shift of for PLCβ3 from storage within the nucleus to its functional site.