Intrathymic proliferation wave essential for Valpha14+ natural killer T cell development depends on c-Myc.
The molecular requirements for invariant Valpha14-bearing natural killer T cells (iNKT) in the thymus are poorly understood. A minute population of approximately 500 newly selected CD69(+)CD24(+) stage 0 (ST0) iNKT cells gives rise to approximately 100 times more CD44(neg/lo)CD24(-) stage 1 (ST1) cells, which then generate similar frequencies of CD44(hi)CD24(-) stage 2 (ST2) and mature iNKT cells. Although the increased number of ST1 compared with ST0 cells indicates the initiation of a proliferation wave in the very early stages of iNKT cell development, details about the controlling mechanism are currently lacking. Here, we show that the transcription factor c-Myc is required for iNKT cell development. Conditional ablation of c-Myc in double-positive thymocytes specifically impacted iNKT but not conventional T cell development. Within the iNKT population, a progressive reduction of iNKT cells was observed starting at ST1 (approximately 50-fold) and ST2 (approximately 350-fold), with a complete lack of mature cells in thymus, spleen, and liver. ST0/ST1 c-Myc-deficient iNKT cells showed reduced proliferation. In contrast, annexin V staining did not reveal increased apoptosis, and transgenic overexpression of BCL-2 did not rescue iNKT cell development in c-Myc-deficient mice. Moreover, expression of known iNKT differentiation factors such as Plzf and Gata3 was not dramatically altered. These, findings provide compelling evidence that c-Myc mediates an intrathymic proliferation wave immediately after agonist selection of iNKT cells and illustrate the importance of this expansion for the generation of mature iNKT cells in vivo.
Committee on Immunology, Department of Medicine, Rheumatology, University of Chicago, Chicago, IL 60637, USA.
Marei
M
Dose
Barry P
BP
Sleckman
Jin
J
Han
Andrea L
AL
Bredemeyer
Albert
A
Bendelac
Fotini
F
Gounari
D000818:Animals; D002454:Cell Differentiation / Q000276:immunology*; D019070:Cell Lineage / Q000276:immunology; D049109:Cell Proliferation; D018076:DNA, Complementary / Q000235:genetics; D005786:Gene Expression Regulation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D055611:Natural Killer T-Cells / Q000166:cytology* / Q000276:immunology*; D016271:Proto-Oncogene Proteins c-myc / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology*
D018076:DNA, Complementary; C489428:Myc protein, mouse; D016271:Proto-Oncogene Proteins c-myc; D016693:Receptors, Antigen, T-Cell, alpha-beta