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Proc Natl Acad Sci U S A. 2018 Apr 24;115(17):E4051-E4060. doi: 10.1073/pnas.1801340115. Epub 2018 Apr 9.

Genome-wide CRISPR screen identifies FAM49B as a key regulator of actin dynamics and T cell activation.

Shang W1,2,3, Jiang Y1,2,3, Boettcher M4, Ding K1,3,5, Mollenauer M6,7, Liu Z1,2,3, Wen X8, Liu C1, Hao P1, Zhao S1,5, McManus MT4, Wei L9, Weiss A10,7, Wang H11.

Author information

1
School of Life Science and Technology, ShanghaiTech University, 201210 Shanghai, China.
2
Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031 Shanghai, China.
3
University of Chinese Academy of Sciences, 100049 Beijing, China.
4
W. M. Keck Center for Noncoding RNAs, Diabetes Center, Department of Microbiology and Immunology, University of California, San Francisco, CA 94143.
5
iHuman Institute, ShanghaiTech University, 201210 Shanghai, China.
6
Division of Rheumatology, Department of Medicine, Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center, University of California, San Francisco, CA 94143.
7
Howard Hughes Medical Institute, University of California, San Francisco, CA 94143.
8
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 510060 Guangzhou, China.
9
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 510060 Guangzhou, China weil9@mail.sysu.edu.cn aweiss@medicine.ucsf.edu wanghp@shanghaitech.edu.cn.
10
Division of Rheumatology, Department of Medicine, Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center, University of California, San Francisco, CA 94143; weil9@mail.sysu.edu.cn aweiss@medicine.ucsf.edu wanghp@shanghaitech.edu.cn.
11
School of Life Science and Technology, ShanghaiTech University, 201210 Shanghai, China; weil9@mail.sysu.edu.cn aweiss@medicine.ucsf.edu wanghp@shanghaitech.edu.cn.

Abstract

Despite decades of research, mechanisms controlling T cell activation remain only partially understood, which hampers T cell-based immune cancer therapies. Here, we performed a genome-wide CRISPR screen to search for genes that regulate T cell activation. Our screen confirmed many of the known regulators in proximal T cell receptor signaling and, importantly, also uncovered a previously uncharacterized regulator, FAM49B (family with sequence similarity 49 member B). FAM49B deficiency led to hyperactivation of Jurkat T cells following T cell receptor stimulation, as indicated by enhancement of CD69 induction, PAK phosphorylation, and actin assembly. FAM49B directly interacted with the active form of the small GTPase Rac, and genetic disruption of the FAM49B-Rac interaction compromised FAM49B function. Thus, FAM49B inhibits T cell activation by repressing Rac activity and modulating cytoskeleton reorganization.

KEYWORDS:

FAM49B; Rac1; TCR signaling; actin cytoskeleton; genome-wide CRISPR screen

PMID:
29632189
PMCID:
PMC5924929
DOI:
10.1073/pnas.1801340115
[Indexed for MEDLINE]
Free PMC Article

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