title: Conditional knockout mice reveal distinct functions for the global transcriptional coactivators CBP and p300 in T-cell development.
abstract: The global transcriptional coactivators CREB-binding protein (CBP) and the closely related p300 interact with over 312 proteins, making them among the most heavily connected hubs in the known mammalian protein-protein interactome. It is largely uncertain, however, if these interactions are important in specific cell lineages of adult animals, as homozygous null mutations in either CBP or p300 result in early embryonic lethality in mice. Here we describe a Cre/LoxP conditional p300 null allele (p300flox) that allows for the temporal and tissue-specific inactivation of p300. We used mice carrying p300flox and a CBP conditional knockout allele (CBPflox) in conjunction with an Lck-Cre transgene to delete CBP and p300 starting at the CD4- CD8- double-negative thymocyte stage of T-cell development. Loss of either p300 or CBP led to a decrease in CD4+ CD8+ double-positive thymocytes, but an increase in the percentage of CD8+ single-positive thymocytes seen in CBP mutant mice was not observed in p300 mutants. T cells completely lacking both CBP and p300 did not develop normally and were nonexistent or very rare in the periphery, however. T cells lacking CBP or p300 had reduced tumor necrosis factor alpha gene expression in response to phorbol ester and ionophore, while signal-responsive gene expression in CBP- or p300-deficient macrophages was largely intact. Thus, CBP and p300 each supply a surprising degree of redundant coactivation capacity in T cells and macrophages, although each gene has also unique properties in thymocyte development.
authors.affiliation: Department of Biochemistry, St. Jude Children's Research Hospital, 332 N. Lauderdale, Memphis, TN 38105, USA.
authors.forename: Lawryn H
authors.initials: LH
authors.lastname: Kasper
authors.forename: Tomofusa
authors.initials: T
authors.lastname: Fukuyama
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Biesen
authors.forename: Fayçal
authors.initials: F
authors.lastname: Boussouar
authors.forename: Caili
authors.initials: C
authors.lastname: Tong
authors.forename: Antoine
authors.initials: A
authors.lastname: de Pauw
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Murray
authors.forename: Jan M A
authors.initials: JM
authors.lastname: van Deursen
authors.forename: Paul K
authors.initials: PK
authors.lastname: Brindle
mesh_terms: D000483:Alleles; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D050882:CREB-Binding Protein / Q000235:genetics / Q000502:physiology*; D002454:Cell Differentiation; D050881:E1A-Associated p300 Protein / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D015870:Gene Expression; D007476:Ionophores / Q000494:pharmacology; D018655:Lymphocyte Count; D016399:Lymphoma, T-Cell / Q000235:genetics; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D010703:Phorbol Esters / Q000494:pharmacology; D011948:Receptors, Antigen, T-Cell; D013154:Spleen / Q000166:cytology / Q000254:growth & development; D013950:Thymus Gland / Q000166:cytology / Q000254:growth & development*; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
chemical_list: D007476:Ionophores; D010703:Phorbol Esters; D011948:Receptors, Antigen, T-Cell; D014409:Tumor Necrosis Factor-alpha; D050882:CREB-Binding Protein; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse