The diverse functions of WASP, the deficiency of which causes Wiskott-Aldrich syndrome (WAS), remain poorly defined. We generated three isogenic WAS models using patient induced pluripotent stem cells and genome editing. These models recapitulated WAS phenotypes and revealed that WASP deficiency causes an upregulation of numerous RNA splicing factors and widespread altered splicing. Loss of WASP binding to splicing factor gene promoters frequently leads to aberrant epigenetic activation. WASP interacts with dozens of nuclear speckle constituents and constrains SRSF2 mobility. Using an optogenetic system, we showed that WASP forms phase-separated condensates that encompasses SRSF2, nascent RNA and active Pol II. The role of WASP in gene body condensates is corroborated by ChIPseq and RIPseq. Together our data reveal that WASP is a nexus regulator of RNA splicing that controls the transcription of splicing factors epigenetically and the dynamics of the splicing machinery through liquid-liquid phase separation.
Bibliographical noteFunding Information:
We would like to thank B. Lubin for advice on hematopoiesis and assistance in cord blood unit procurement; C. Cole, R. Walker, J. Lieu, R. Tonai, and M. Swearingen for providing cord blood samples; Y. Zheng and Y. Tian for assistance on hematopoietic differentiation and flow cytometry; A. Shirbini for assistance on MST experiment and analysis; members of the Belmonte and Li lab for helpful discussions; Y. Zhang, A.T. Gutiérrez, A. Geobl, R.D. Soligalla and Y. Hishida for technical assistance, J.H. Xiong for help with MATLAB. L. Mack, J. Olvera, C. O’Connor, E. O’Connor and K. Marquez for help with flow cytometry; D. O’Keefe and M. Wang for critical reading of the manuscript; M. Schwarz, P. Schwarz, C. Xia, X. Zhang, and M.K.Y. Sicat for administrative help. We thank KAUST Visualization Core Lab for Avizo software support. We also thank KAUST Bioscience core lab for sequencing support and KAUST Imaging and Characterization core lab for help with confocal microscopy. The research of the Li laboratory was supported by KAUST Office of Sponsored Research (OSR), under award numbers BAS/1/1080-01 and URF/1/4716-01. This work was supported by the Waitt Advanced Biophotonics Core Facility of the Salk Institute with funding from NIH-NCI CCSG: P30 014195, NINDS Neuroscience Core Grant, and the Waitt Foundation. G.H.L. was supported by the National Key Research and Development Program of China (2020YFA0804000), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA16010000), the National Natural Science Foundation of China (Grant Nos. 81921006, 92149301, 92168201). J.C.I.B. was supported by grants from The Moxie Foundation, G. Harold and Leila Y. Mathers Charitable Foundation.
© 2022, The Author(s).
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)