ABSTRACT
TIMP-1, a well-known MMP inhibitor, displays other biological activities such as cell survival, proliferation and differentiation in hematopoietic cells. In this report, we investigated the role of the Src-related kinase Lyn in TIMP-1 induced UT-7 erythroleukemic cell survival. We showed that (i) tyrosine 507 of Lyn was dephosphorylated and Lyn kinase activity enhanced by TIMP-1, (ii) Lyn silencing suppressed TIMP-1 anti-apoptotic activity and (iii) Lyn was activated upstream the JAK2/PI 3-kinase/Akt pathway. Our data suggest a novel role for Lyn in erythroid cell survival.
Subject(s)
Erythroid Cells , Tissue Inhibitor of Metalloproteinase-1/metabolism , src-Family Kinases/physiology , Cell Survival/drug effects , Cell Survival/genetics , Cell Survival/physiology , Enzyme Activation/drug effects , Erythroid Cells/cytology , Erythroid Cells/metabolism , Erythroid Cells/pathology , Gene Expression Regulation, Leukemic/drug effects , Humans , Janus Kinase 2/metabolism , Leukemia, Erythroblastic, Acute/genetics , Leukemia, Erythroblastic, Acute/metabolism , Leukemia, Erythroblastic, Acute/pathology , Models, Biological , Oncogene Protein v-akt/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Phosphorylation/drug effects , RNA, Small Interfering/pharmacology , Signal Transduction/drug effects , Signal Transduction/genetics , Signal Transduction/physiology , Tissue Inhibitor of Metalloproteinase-1/physiology , Tumor Cells, Cultured , src-Family Kinases/antagonists & inhibitors , src-Family Kinases/genetics , src-Family Kinases/metabolismABSTRACT
Besides its ability to inhibit MMP activity, TIMP-1 exhibits other biological functions. We earlier reported that TIMP-1 induced UT-7 erythroid cell survival through activation of the JAK2/PI 3-kinase/Akt pathway and we now aim to determine whether the TIMP-1 anti-apoptotic effect requires MMP involvement. We first show that proMMP-9 was expressed in UT-7 cells and associated with the cell plasma membrane. Such proMMP-9 localization was crucial for TIMP-1 intracellular signalling since (i) TIMP-1 specifically bound to proMMP-9 and (ii) proMMP-9 silencing abrogated the TIMP-1 effect. We also demonstrated that TIMP-1 anti-apoptotic effect was independent on MMP inhibition since MMP-9 function blocking antibodies as well as a synthetic MMP inhibitor were unable to reproduce TIMP-1 effect. Nevertheless, these compounds prevented TIMP-1 binding to proMMP-9 and subsequently abolished TIMP-1-induced cell survival. We finally demonstrated that CD44 anchored proMMP-9 to the plasma membrane and enabled TIMP-1-mediated signal transduction. Therefore, our results indicate that the anti-apoptotic signalling of TIMP-1 depends on the formation of a ternary complex between TIMP-1, proMMP-9 and CD44 at the UT-7 erythroid cell surface.