Biology subjects

Sidwell, T.

Publications and source records attributed to Sidwell, T..

2 recordsLinked to original sources

bioRxiv2026

Bcl11b dose-dependently regulates positive selection of CD8 T cells to the virtual memory fate

Virtual memory T cells are increasingly recognized as a functionally distinct lineage within the CD8 T cell pool, but when and how commitment to the lineage is enforced remain poorly understood. Here we demonstrate that TVM lineage choice is exceptionally sensitive to dosage and repression competence of the key T cell transcription factor Bcl11b. Three different genetic models of slightly reduced Bcl11b each biased CD8 cell development to TVM generation without deregulating effector differentiation. Timed conditional knockouts and adoptive transfers narrowed the developmental window and showed that Bcl11b levels determine diversion to virtual memory fate uniquely during intrathymic positive selection. Whereas total Bcl11b loss disrupts TCR signalling, a <2-fold dose reduction of Bcl11b enhanced selective responses to TCR stimulation. Chromatin accessibility profiling and single cell RNA-seq indicated that Bcl11b dose reduction redirects cells to the TVM fate, from the late cycling fraction of mature CD8SP thymocytes, by a mechanism independent of previously described cytokine-driven pathways.

immunology↗

bioRxiv2025

T cell development from expanded hematopoietic progenitors reveals progression control by Lmo2, Erg, Spi1, Hoxa9, and Meis1

To gain access to the earliest stages of T cell development, we adapted a serum-free culture system that expands hematopoietic stem and progenitor-like cells. These expanded cells efficiently undergo normal T-cell differentiation in vivo and in vitro, verified by early gene expression trajectories from single-cell RNA sequencing, though their absolute differentiation speed is slower than that of fresh progenitors and can be modulated with cytokine priming. Leveraging this expansion system to observe the first T-lineage events, we revealed that initial Notch activation immediately induces chromatin opening and transcriptional activation of the TCR-C{beta} locus. Additionally, acute CRISPR knockouts confirmed T-lineage entry requirements for Ikzf1, Hes1, Gabpa, and Myb while revealing that Lmo2, Erg, Spi1, Hoxa9, and Meis1 retard developmental progression with differing effects on proliferation. Endogenous expression of the stem, progenitor, and leukemia-associated factor Lmo2 markedly restrains initiation of the T cell program, with Lmo2 knockout greatly accelerating germline TCR{beta} locus transcription and expression of Tcf7, Gata3, Runx family, and E protein genes and their targets.

immunology↗