title: Gamma -secretase inhibitors repress thymocyte development.
abstract: A major therapeutic target in the search for a cure to the devastating Alzheimer's disease is gamma-secretase. This activity resides in a multiprotein enzyme complex responsible for the generation of Abeta42 peptides, precipitates of which are thought to cause the disease. Gamma-secretase is also a critical component of the Notch signal transduction pathway; Notch signals regulate development and differentiation of adult self-renewing cells. This has led to the hypothesis that therapeutic inhibition of gamma-secretase may interfere with Notch-related processes in adults, most alarmingly in hematopoiesis. Here, we show that application of gamma-secretase inhibitors to fetal thymus organ cultures interferes with T cell development in a manner consistent with loss or reduction of Notch1 function. Progression from an immature CD4-/CD8- state to an intermediate CD4+/CD8+ double-positive state was repressed. Furthermore, treatment beginning later at the double-positive stage specifically inhibited CD8+ single-positive maturation but did not affect CD4+ single-positive cells. These results demonstrate that pharmacological gamma-secretase inhibition recapitulates Notch1 loss in a vertebrate tissue and present a system in which rapid evaluation of gamma-secretase-targeted pharmaceuticals for their ability to inhibit Notch activity can be performed in a relevant context.
authors: Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors: B K
authors: BK
authors: Hadland
authors: N R
authors: NR
authors: Manley
authors: D
authors: D
authors: Su
authors: G D
authors: GD
authors: Longmore
authors: C L
authors: CL
authors: Moore
authors: M S
authors: MS
authors: Wolfe
authors: E H
authors: EH
authors: Schroeter
authors: R
authors: R
authors: Kopan
mesh_terms: D053829:Amyloid Precursor Protein Secretases; D000818:Animals; D016282:Aspartic Acid Endopeptidases; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D010450:Endopeptidases / Q000378:metabolism*; D006801:Humans; D007668:Kidney; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D016296:Mutagenesis; D009924:Organ Culture Techniques; D011480:Protease Inhibitors / Q000494:pharmacology*; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins / Q000378:metabolism; D017384:Sequence Deletion; D013601:T-Lymphocytes / Q000502:physiology*; D013950:Thymus Gland / Q000196:embryology / Q000276:immunology; D014157:Transcription Factors; D014162:Transfection
chemical_list: D008565:Membrane Proteins; C497761:NOTCH1 protein, human; C497762:Notch1 protein, mouse; D011480:Protease Inhibitors; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D014157:Transcription Factors; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; C509282:Bace1 protein, mouse