Dok-related protein negatively regulates T cell development via its RasGTPase-activating protein and Nck docking sites.
Downstream of kinase (Dok)-related protein (DokR, also known as p56(dok)/FRIP/Dok-R) is implicated in cytokine and immunoreceptor signaling in myeloid and T cells. Tyrosine phosphorylation induces DokR to bind the signal relay molecules, RasGTPase-activating protein (RasGAP) and Nck. Here, we have examined the function of DokR during hematopoietic development and the requirement for RasGAP and Nck binding sites in its biological function. Retroviral-mediated expression of DokR in bone marrow cells dramatically inhibited their capacity to form colonies in vitro in response to the cytokines macrophage colony-stimulating factor and stem cell factor, whereas responses to interleukin-3 and granulocyte macrophage colony-stimulating factor were only weakly affected. When introduced into lethally irradiated mice, hematopoietic cells expressing DokR showed a drastically reduced capacity to repopulate lymphoid tissues. Most notably, DokR dramatically reduced repopulation of the thymus, in part by reducing the number of T cell precursors seeding in the thymus, but equally, through inhibiting the transition of CD4(-)CD8(-) to CD4(+)CD8(+) T cells. Consequently, the number of mature peripheral T cells was markedly reduced. In contrast, a minimal effect on B cell and myeloid lineage development was observed. Importantly, functional RasGAP and Nck binding sites were found to be essential for the biological effects of DokR in vitro and in vivo.
Gugasyan
Raffi
R
Walter and Eliza Hall Institute of Medical Research, University of Melbourne, Parkville 3050, Australia.
Quilici
Cathy
C
I
Stacey T T
ST
Grail
Dianne
D
Verhagen
Anne M
AM
Roberts
Andrew
A
Kitamura
Toshio
T
Dunn
Ashley R
AR
Lock
Peter
P
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D001665:Binding Sites; D001854:Bone Marrow Cells / Q000378:metabolism; D015704:CD4 Antigens / Q000096:biosynthesis; D016827:CD8 Antigens / Q000096:biosynthesis; D002352:Carrier Proteins / Q000502:physiology*; D002455:Cell Division; D019070:Cell Lineage; D002469:Cell Separation; D005260:Female; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D015151:Immunoblotting; D007377:Interleukin-3 / Q000378:metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism*; D009154:Mutation; D015513:Oncogene Proteins / Q000378:metabolism*; D010641:Phenotype; D010750:Phosphoproteins / Q000502:physiology*; D010766:Phosphorylation; D011233:Precipitin Tests; D012190:Retroviridae / Q000235:genetics; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology; D014443:Tyrosine / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D015704:CD4 Antigens; D016827:CD8 Antigens; D002352:Carrier Proteins; C498444:Dok2 protein, mouse; D007377:Interleukin-3; D008164:Luminescent Proteins; C078332:Nck protein; D015513:Oncogene Proteins; D010750:Phosphoproteins; D049452:Green Fluorescent Proteins; D014443:Tyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D020559:Monomeric GTP-Binding Proteins