title: Ikaros DNA-binding proteins as integral components of B cell developmental-stage-specific regulatory circuits.
abstract: Ikaros DNA-binding proteins are critical for the development of lymphocytes and other hematopoietic lineages, but it remains unclear how they cooperate with other regulators of signaling and transcription to achieve ordered gene expression during development. Here, we show that Ikaros proteins regulate the pre-BCR component lambda5 in a stage-specific manner. In pre-BI cells, Ikaros modulated lambda5 expression in competition with the transcriptional activator EBF. This required Ikaros binding to the Igll1 (lambda5) promoter and was abolished either by mutation of the Ikaros DNA-binding domain or by deletion of a single Ikaros site from the Igll1 promoter. At the transition from the pre-BI to pre-BII stage, the expression of the Ikaros family member Aiolos was upregulated and required for the efficient silencing of Igll1. Aiolos expression was controlled by pre-BCR signals via the adaptor protein SLP-65. Thus, pre-BCR signaling regulates Aiolos and the silencing of Igll1 via a developmental-stage-specific feedback loop.
authors.affiliation: Lymphocyte Development Group, MRC Clinical Sciences Centre, Imperial College London, Du Cane Road, London W12 0NN, UK.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Thompson
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Cobb
authors.forename: Pierangela
authors.initials: P
authors.lastname: Sabbattini
authors.forename: Sonja
authors.initials: S
authors.lastname: Meixlsperger
authors.forename: Vania
authors.initials: V
authors.lastname: Parelho
authors.forename: David
authors.initials: D
authors.lastname: Liberg
authors.forename: Benjamin
authors.initials: B
authors.lastname: Taylor
authors.forename: Niall
authors.initials: N
authors.lastname: Dillon
authors.forename: Katia
authors.initials: K
authors.lastname: Georgopoulos
authors.forename: Hassan
authors.initials: H
authors.lastname: Jumaa
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Smale
authors.forename: Amanda G
authors.initials: AG
authors.lastname: Fisher
authors.forename: Matthias
authors.initials: M
authors.lastname: Merkenschlager
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D001402:B-Lymphocytes / Q000737:chemistry / Q000276:immunology*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation; D020868:Gene Silencing; D051740:Ikaros Transcription Factor / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D007147:Immunoglobulin Light Chains / Q000235:genetics*; D054444:Immunoglobulin Light Chains, Surrogate; D008213:Lymphocyte Activation / Q000235:genetics; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D011401:Promoter Regions, Genetic / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics* / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C113939:B cell linker protein; D004268:DNA-Binding Proteins; C489921:Ebf1 protein, mouse; C491396:Ikzf3 protein, mouse; D007147:Immunoglobulin Light Chains; D054444:Immunoglobulin Light Chains, Surrogate; D008562:Membrane Glycoproteins; D015534:Trans-Activators; D051740:Ikaros Transcription Factor