Page 124 - 2022_03-Haematologica-web

Ferrata Storti Foundation
Haematologica 2022 Volume 107(3):680-689
ZRSR1 co-operates with ZRSR2 in regulating splicing of U12-type introns in murine hematopoietic cells
Vikas Madan,1* Zeya Cao,1,2* Weoi Woon Teoh,1 Pushkar Dakle,1 Lin Han,1,2 Pavithra Shyamsunder,1,3 Maya Jeitany,1,4 Siqin Zhou,1 Jia Li,1 Hazimah Binte Mohd Nordin,1 Jizhong Shi,1 Shuizhou Yu,1 Henry Yang,1 Md Zakir Hossain,1 Wee Joo Chng,1,2,5# and H. Phillip Koeffler1,6,7#
1Cancer Science Institute of Singapore, National University of Singapore, Singapore; 2Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; 3Programme in Cancer and Stem Cell Biology, Duke–NUS Medical School, Singapore; 4School of Biological Sciences, Nanyang Technological University, Singapore; 5Hematology-Oncology, National University Cancer Institute, National University Hospital Singapore, Singapore; 6Cedars-Sinai Medical Center, Division of Hematology/Oncology, UCLA School of Medicine, Los Angeles, CA, USA and 7National University Cancer Institute, National University Hospital Singapore, Singapore.
*VM and ZC contributed equally as co-first authors. #WJC and HPK contributed equally as co-senior authors.
ABSTRACT
Recurrent loss-of-function mutations of spliceosome gene, ZRSR2, occur in myelodysplastic syndromes (MDS). Mutation/loss of ZRSR2 in human myeloid cells primarily causes impaired splicing of the U12-type introns. In order to further investigate the role of this splice factor in RNA splicing and hematopoietic development, we gener- ated mice lacking ZRSR2. Unexpectedly, Zrsr2-deficient mice developed normal hematopoiesis with no abnormalities in myeloid differentiation evident in either young or ≥1-year old knockout mice. Repopulation abil- ity of Zrsr2-deficient hematopoietic stem cells was also unaffected in both competitive and non-competitive reconstitution assays. Myeloid progenitors lacking ZRSR2 exhibited mis-splicing of U12-type introns, however, this phenotype was moderate compared to the ZRSR2-defi- cient human cells. Our investigations revealed that a closely related homolog, Zrsr1, expressed in the murine hematopoietic cells, but not in human cells contributes to splicing of U12-type introns. Depletion of Zrsr1 in Zrsr2 KO myeloid cells exacerbated retention of the U12-type introns, thus highlighting a collective role of ZRSR1 and ZRSR2 in murine U12-spliceosome. We also demonstrate that aberrant retention of U12-type introns of MAPK9 and MAPK14 leads to their reduced pro- tein expression. Overall, our findings highlight that both ZRSR1 and ZRSR2 are functional components of the murine U12-spliceosome, and depletion of both proteins is required to accurately model ZRSR2-mutant MDS in mice.
Introduction
Mutations in RNA splicing factors constitute the leading class of genetic alter- ations in myelodysplastic syndromes (MDS).1-4 Somatic mutations in spliceosome genes, SF3B1, SRSF2, U2AF1 and ZRSR2 are observed in >50% of MDS.2,3 These mutations are early events during disease development and largely occur mutually exclusive of each other.1-5 Intense efforts in the last few years have enhanced our understanding of the impact of spliceosome mutations on RNA splicing and defined a mis-splicing pattern for each mutation.6-17 Animal models expressing mutant hotspots of splice factor genes - SRSF2 (P95H), SF3B1 (K700E) and U2AF1 (S34F) - have enabled elucidation of consequences of these genetic lesions on RNA splicing and hematopoietic development.6,7,12,15,16,18-20 Unlike mutational hotspots observed in
Myelodysplastic Syndromes
Correspondence:
VIKAS MADAN
vikasmadan@aol.com
Received: May 24, 2020. Accepted: March 1, 2021. Pre-published: March 11, 2021.
https://doi.org/10.3324/haematol.2020.260562 ©2022 Ferrata Storti Foundation
Material published in Haematologica is covered by copyright. All rights are reserved to the Ferrata Storti Foundation. Use of published material is allowed under the following terms and conditions: https://creativecommons.org/licenses/by-nc/4.0/legalcode. Copies of published material are allowed for personal or inter- nal use. Sharing published material for non-commercial pur- poses is subject to the following conditions: https://creativecommons.org/licenses/by-nc/4.0/legalcode, sect. 3. Reproducing and sharing published material for com- mercial purposes is not allowed without permission in writing from the publisher.
680
haematologica | 2022; 107(3)
ARTICLE