Molecular role of TGF-beta, secreted from a new type of CD4+ suppressor T cell, NY4.2, in the prevention of autoimmune IDDM in NOD mice.
A new type of CD4+ T cell clone (NY4.2) isolated from pancreatic islet-infiltrated lymphocytes of acutely diabetic non-obese diabetic (NOD) mice prevents the development of insulin-dependent diabetes mellitus (IDDM) in NOD mice, as well as the recurrence of autoimmune diabetes in syngeneic islet-transplanted NOD mice. It has been demonstrated that the cytokine TGF-beta, secreted from the cells of this clone, is the substance which prevents autoimmune IDDM. This investigation was initiated to determine the molecular role TGF-beta plays in the prevention of autoimmune IDDM by determining its effect on IL-2-induced signal transduction in Con A-activated NOD mouse splenocytes and HT-2 cells. First, we determined whether TGF-beta, secreted from NY4.2 T cells, inhibits IL-2-dependent T cell proliferation in HT-2 cells (IL-2-dependent T cell line) and NOD splenocytes. We found that TGF-beta suppresses IL-2-dependent T cell proliferation. Second, we determined whether TGF-beta inhibits the activation of Janus kinases (JAKs), as well as signal transducers and activators of transcription (STAT) proteins, involved in an IL-2-induced signalling pathway that normally leads to the proliferation of T cells. We found that TGF-beta inhibited tyrosine phosphorylation of JAK1, JAK3, STAT3 and STAT5 in Con A blasts from NOD splenocytes and HT-2 cells. Third, we examined whether TGF-beta inhibits the cooperation between STAT proteins and mitogen-activated protein kinase (MAPK), especially extracellular signal-regulated kinase 2 (ERK2). We found that TGF-beta inhibited the association of STAT3 and STAT5 with ERK2 in Con A blasts from NOD splenocytes and HT-2 cells. On the basis of these observations, we conclude that TGF-beta may interfere with signal transduction via inhibition of the IL-2-induced JAK/STAT pathway and inhibition of the association of STAT proteins with ERK2 in T cells from NOD splenocytes, resulting in the inhibition of IL-2-dependent T cell proliferation. TGF-beta-mediated suppression of T cell activation may be responsible for the prevention of effector T cell-mediated autoimmune IDDM in NOD mice by TGF-beta-producing CD4+ suppressor T cells.
Han
H S
HS
Department of Microbiology and Infectious Diseases, Julia McFarlane Diabetes Research Centre, Faculty of Medicine, The University of Calgary, Alberta, Canada.
Jun
H S
HS
Utsugi
T
T
Yoon
J W
JW
D000209:Acute-Phase Proteins / Q000378:metabolism; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology* / Q000517:prevention & control*; D015536:Down-Regulation / Q000276:immunology; D004789:Enzyme Activation; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000276:immunology; D053613:Janus Kinase 1; D053616:Janus Kinase 3; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D016688:Mice, Inbred NOD; D008894:Milk Proteins; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000502:physiology*
D000209:Acute-Phase Proteins; D004268:DNA-Binding Proteins; D007376:Interleukin-2; D008894:Milk Proteins; D015375:Receptors, Interleukin-2; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D011505:Protein-Tyrosine Kinases; C507905:Jak1 protein, mouse; C507935:Jak3 protein, mouse; D053613:Janus Kinase 1; D053616:Janus Kinase 3; D017871:Calcium-Calmodulin-Dependent Protein Kinases