CRISPR/Cas9 Screens Reveal Multiple Layers of B cell CD40 Regulation

Chang Jiang (1, 2) , Stephen J. Trudeau (1, 2) , Taek-Chin Cheong (1) , Rui Guo (1, 2) , Mingxiang Teng (3) , Liang Wei Wang (1, 2) , Zhonghao Wang (1, 4, 2) , Chiara Pighi (2, 1) , Carole Gautier-Courteille (5, 6) , Yijie Ma (2, 1) , Sizun Jiang (1, 2) , Chong Wang (2) , Bo Zhao (2) , Luc Paillard (5, 6) , John G. Doench (7) , Roberto Chiarle (8, 1) , Benjamin E Gewurz (3, 1, 2)

1 HMS - Harvard Medical School [Boston]
2 Brigham and Women's Hospital [Boston]
3 H. Lee Moffitt Cancer Center and Research Institute
4 SCU - Sichuan University [Chengdu]
5 IGDR - Institut de Génétique et Développement de Rennes
6 Biosit : Biologie - Santé - Innovation Technologique - Structure Fédérative de Recherche en Biologie et Santé de Rennes
7 BROAD INSTITUTE - Broad Institute of MIT and Harvard
8 UNITO - Università degli studi di Torino = University of Turin

CD40 has major roles in B cell development, activation, and germinal center responses. CD40 hypoactivity causes immunodeficiency whereas its overexpression causes autoimmunity and lymphomagenesis. To systematically identify B cell autonomous CD40 regulators, we use CRISPR/Cas9 genome-scale screens in Daudi B cells stimulated by multimeric CD40 ligand. These highlight known CD40 pathway components and reveal multiple additional mechanisms regulating CD40. The nuclear ubiquitin ligase FBXO11 supports CD40 expression by targeting repressors CTBP1 and BCL6. FBXO11 knockout decreases primary B cell CD40 abundance and impairs class-switch recombination, suggesting that frequent lymphoma monoallelic FBXO11 mutations may balance BCL6 increase with CD40 loss. At the mRNA level, CELF1 controls exon splicing critical for CD40 activity, while the N6-adenosine methyltransferase WTAP negatively regulates CD40 mRNA abundance. At the protein level, ESCRT negatively regulates activated CD40 levels while the negative feedback phosphatase DUSP10 limits downstream MAPK responses. These results serve as a resource for future studies and highlight potential therapeutic targets.

Keywords: ESCRT; MAP kinase; CRISPR screen; N6-Methyladenosine; NF-kappaB; TNF receptor superfamily; germinal center; humoral immunity; immunodeficiency; B cell activation

Domains: Life Sciences [q-bio]; Cellular Biology; Subcellular Processes [q-bio.SC]; Life Sciences [q-bio]; Biochemistry, Molecular Biology; Genomics [q-bio.GN]; Life Sciences [q-bio]; Immunology; Adaptive immunology

Chang Jiang, Stephen J. Trudeau, Taek-Chin Cheong, Rui Guo, Mingxiang Teng, et al.. CRISPR/Cas9 Screens Reveal Multiple Layers of B cell CD40 Regulation. Cell Reports, 2019, 28 (5), pp.1307-+. ⟨10.1016/j.celrep.2019.06.079⟩. ⟨hal-02278690⟩