Optimal chemotactic responses of leukemic T cells to stromal cell-derived factor-1 requires the activation of both class IA and IB phosphoinositide 3-kinases.
Stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 are a multifunctional chemokine/receptor system with essential roles in the development of the immune system and other aspects of embryogenesis, including vascularization and organ development. SDF-1 is also a potent chemoattractant for T cells and has roles in both inflammation and immune homeostasis. Our group has previously demonstrated that phosphoinositide 3-kinase (PI 3-kinase) is activated in SDF-1-stimulated T cells and is indeed required for SDF-1-mediated chemotaxis. In this study Jurkat clones were established, stably expressing dominant negative constructs of class IA and class IB PI 3-kinases under the control of the tetracycline off inducible gene system, to determine the relative roles of these PI 3-kinases in SDF-1 signaling. Our results show that expression of either kinase-dead PI3Kgamma (KD-PI3Kgamma) or Deltap85 (a construct unable to bind class I(A) p110alpha, -beta, or -delta) leads to a partial inhibition of SDF-1-stimulated protein kinase B phosphorylation, but had no effect on SDF-1-induced phosphorylation of the mitogen-activated protein kinase ERK1/2. Functional studies demonstrated that expression of KD-PI3Kgamma markedly inhibited SDF-1-mediated chemotaxis, typically eliciting 40-60% inhibition. Interestingly, the expression of Deltap85 also leads to inhibition of the SDF-1-mediated chemotactic response, albeit to a much lesser extent than achieved with the KD-PI3Kgamma mutant, typically in the range of 20-40% inhibition. Furthermore, the inhibition of chemotaxis by the expression of dominant negative class IA or class IB PI 3-kinases could be enhanced by the presence of the PI 3-kinase inhibitor LY294002. Together, these results demonstrate that optimal chemotactic response of leukemic T cells to SDF-1 requires the activation of both class IA and class IB PI 3-kinases.
Curnock
Adam P
AP
Department of Pharmacy and Pharmacology, Bath University, Bath, United Kingdom.
Sotsios
Yannis
Y
Wright
Karen L
KL
Ward
Stephen G
SG
D000818:Animals; D002417:Cattle; D002464:Cell Migration Inhibition; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000037:antagonists & inhibitors / Q000502:physiology*; D002634:Chemotaxis, Leukocyte / Q000276:immunology*; D002867:Chromones / Q000494:pharmacology; D058544:Class Ib Phosphatidylinositol 3-Kinase; D002999:Clone Cells; D004357:Drug Synergism; D004789:Enzyme Activation / Q000235:genetics / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000276:immunology; D005822:Genetic Vectors; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000037:antagonists & inhibitors / Q000502:physiology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D019169:Jurkat Cells; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D013552:Swine; D016176:T-Lymphocyte Subsets / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D013752:Tetracycline / Q000378:metabolism
D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D002867:Chromones; D058544:Class Ib Phosphatidylinositol 3-Kinase; D004791:Enzyme Inhibitors; D007334:Insulin-Like Growth Factor I; D007527:Isoenzymes; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D013752:Tetracycline; C515255:CXCL12 protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C546760:PIK3CG protein, human