Role of interleukin-7 in T-cell development from hematopoietic stem cells.
All lymphocytes are derived from hematopoietic stem cells (HSC). The interleukin-7 receptor (IL-7R) transduces non-redundant signals for both T and B-cell development from HSC. The upregulation of the IL-7R occurs at the stage of the clonogenic common lymphoid progenitor, a recently identified population that can give rise to all lymphoid lineages (T, B and natural killer cells) at a single cell level. The IL-7R plays a critical role in the rearrangement of immunoglobulin heavy chain genes required for B-cell development. IL-7R expression is critically regulated in developing thymocytes; thymocytes that fail the positive selection process downregulate the IL-7R, but those undergoing positive selection upregulate or maintain IL-7R expression. Recent data indicate that IL-7 signaling enhances the survival of developing thymocytes and mature T cells, presumably by its upregulating Bcl-2. Detailed analysis of the signaling cascades activated by the IL-7R may help to reveal the differential roles of IL-7 signaling in T and B-cell development.
Akashi
K
K
Department of Pathology, Standford University School of Medicine 94305, USA. Akashi@Darwin.Stanford.edu
Kondo
M
M
Weissman
I L
IL
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology; D002454:Cell Differentiation; D005803:Genes, Immunoglobulin; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D015851:Interleukin-7 / Q000502:physiology*; D008214:Lymphocytes; D016693:Receptors, Antigen, T-Cell, alpha-beta; D020395:Receptors, Interleukin-7 / Q000502:physiology; D011995:Recombination, Genetic; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology* / Q000502:physiology; D013950:Thymus Gland / Q000166:cytology
D015851:Interleukin-7; D016693:Receptors, Antigen, T-Cell, alpha-beta; D020395:Receptors, Interleukin-7