New insights on human T cell development by quantitative T cell receptor gene rearrangement studies and gene expression profiling

Abstract

To gain more insight into initiation and regulation of T cell receptor (TCR) gene rearrangement during human T cell development, we analyzed TCR gene rearrangements by quantitative PCR analysis in nine consecutive T cell developmental stages, including CD34+ lin− cord blood cells as a reference. The same stages were used for gene expression profiling using DNA microarrays. We show that TCR loci rearrange in a highly ordered way (TCRD-TCRG-TCRB-TCRA) and that the initiating Dδ2-Dδ3 rearrangement occurs at the most immature CD34+CD38−CD1a− stage. TCRB rearrangement starts at the CD34+CD38+CD1a− stage and complete in-frame TCRB rearrangements were first detected in the immature single positive stage. TCRB rearrangement data together with the PTCRA (pTα) expression pattern show that human TCRβ-selection occurs at the CD34+CD38+CD1a+ stage. By combining the TCR rearrangement data with gene expression data, we identified candidate factors for the initiation/regulation of TCR recombination. Our data demonstrate that a number of key events occur earlier than assumed previously; therefore, human T cell development is much more similar to murine T cell development than reported before.

Generation of T Cells from Human Embryonic Stem Cell-Derived Hematopoietic Zones

“…The GeneScan was performed by two multiplex PCR as previously described by the BIOMED-2 Concerted Action (14). Each analysis was performed in duplo, including hESC and adult PBMC as negative and positive control, respectively.…”

“…The genetic loci encoding the TCR undergo sequential genomic rearrangements, with randomly chosen variable (V), diversity (D), and joining (J) segments being assembled to form a variable TCR repertoire (14). To test whether the hESC-derived T lineage cells display a polyclonal repertoire, we performed a GeneScan analysis.…”

Mécanisme d’action des oncogènes à homéodomaine TLX dans les LAL-T

“…Un métabolisme primitif nécessite égale-ment que ces polymères soient capables de se replier dans des structures tertiaires stables ayant des fonctionnalités élaborées telles que la reconnaissance d'un ligand et la catalyse [5]. Parmi les systèmes étudiés, l'acide nucléique (3', 2')--L-thréose (ANT, Figure 1) pourrait jouer le rôle de précur-seur de l'ARN en raison de sa simplicité structurale -son squelette est constitué de thréoses qui ont un carbone de moins que les riboses de l'ARN -et de sa capacité à former des structures hélicoïdales stables avec des brins complémentaires d'ANT ou d'ARN [6][7][8].…”

Identification of TMEM131L as a Novel Regulator of Thymocyte Proliferation in Humans

“…Downstream transition from the DN1 (CD34 int CD7 + CD5 + CD1a 2 ) to DN2 (CD34 lo CD7 + CD5 + CD1a + ) stage coincides with definitive T lineage commitment and initiation of TCRb D-J rearrangements (6). Subsequently, thymocytes reach the DN3a (CD34 2 CD4 int CD8a 2 ) stage, when they stop proliferating to complete V-DJb rearrangement, and pass through the b-selection checkpoint to become DN3b thymocytes (CD34 2 CD4 int CD8a + ) (3,7). Later on, post-bselection DN3b thymocytes further upregulate CD4, acquire expression of CD8b-chain, and reach the double-positive (DP) stage where rearrangement of the TCRa locus takes place.…”

“…F ollowing extravasation from the blood, early thymus immigrants establish lymphostromal synapses with cortical thymic epithelial cells, which triggers proliferation and drives their specification along the T cell lineage through the simultaneous activation of the IL-7R, c-Kit, sonic hedgehog, Wnt/ LEF/T cell factor (TCF), and Notch signaling pathways (1)(2)(3). Most current evidence suggests that activation of the Frizzled/ LRP6 receptor complex by its cognate ligands (Wnt1-4) regulates survival and proliferation of early thymus immigrants, whereas Notch1 ligation by Delta-like 4 also drives commitment toward the T lineage (4).…”