T cell factor 1 regulates thymocyte survival via a RORγt-dependent pathway.
Survival of CD4(+)CD8(+) double-positive (DP) thymocytes plays a critical role in shaping the peripheral T cell repertoire. However, the mechanisms responsible for the regulation of DP thymocyte lifespan remain poorly understood. In this work, we demonstrate that T cell factor (TCF)-1 regulates DP thymocyte survival by upregulating RORγt. Microarray analysis revealed that RORγt was significantly downregulated in TCF-1(-/-) thymocytes that underwent accelerated apoptosis, whereas RORγt was greatly upregulated in thymocytes that had enhanced survival due to transgenic expression of a stabilized β-catenin (β-cat(Tg)), a TCF-1 activator. Both TCF-1(-/-) and RORγt(-/-) DP thymocytes underwent similar accelerated apoptosis. Forced expression of RORγt successfully rescued TCF-1(-/-) DP thymocytes from apoptosis, whereas ectopically expressed TCF-1 was not able to rescue the defective T cell development because of the lack of RORγt-supported survival. Furthermore, activation of TCF-1 by stabilized β-catenin was able to enhance DP thymocyte survival only in the presence of RORγt, indicating that RORγt acts downstream of TCF-1 in the regulation of DP thymocyte survival. Moreover, β-catenin/TCF-1 directly interacted with the RORγt promoter region and stimulated its activity. Therefore, our data demonstrated that TCF-1 enhances DP thymocyte survival through transcriptional upregulation of RORγt, which we previously showed is an essential prosurvival molecule for DP thymocytes.
Division of Immunology, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA.
Ruiqing
R
Wang
Huimin
H
Xie
Zhaofeng
Z
Huang
Jian
J
Ma
Xianfeng
X
Fang
Yan
Y
Ding
Zuoming
Z
Sun
D000818:Animals; D017209:Apoptosis / Q000276:immunology; D015153:Blotting, Western; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology*; D002469:Cell Separation; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D047369:Chromatin Immunoprecipitation; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D051538:Hepatocyte Nuclear Factor 1-alpha; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D046228:Microarray Analysis; D057132:Nuclear Receptor Subfamily 1, Group F, Member 3 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D051822:T Cell Transcription Factor 1 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D060168:Thymocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D014162:Transfection
D051538:Hepatocyte Nuclear Factor 1-alpha; C496488:Hnf1a protein, mouse; D057132:Nuclear Receptor Subfamily 1, Group F, Member 3; D051822:T Cell Transcription Factor 1