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Butler E, Xu L, Rakheja D, Schwettmann B, Toubbeh S, Guo L, Kim J, Skapek SX, Zheng Y. Exon skipping in genes encoding lineage-defining myogenic transcription factors in rhabdomyosarcoma. Cold Spring Harb Mol Case Stud 2022; 8:mcs.a006190. [PMID: 35933111 PMCID: PMC9528969 DOI: 10.1101/mcs.a006190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 07/25/2022] [Indexed: 11/24/2022] Open
Abstract
Rhabdomyosarcoma (RMS) is a childhood sarcoma composed of myoblast-like cells, which suggests a defect in terminal skeletal muscle differentiation. To explore potential defects in the differentiation program, we searched for mRNA splicing variants in genes encoding transcription factors driving skeletal muscle lineage commitment and differentiation. We studied two RMS cases and identified altered splicing resulting in "skipping" the second of three exons in MYOD1. RNA-Seq data from 42 tumors and additional RMS cell lines revealed exon 2 skipping in both MYOD1 and MYF5 but not in MYF6 or MYOG. Complementary molecular analysis of MYOD1 mRNA found evidence for exon skipping in 5 additional RMS cases. Functional studies showed that so-called MYODΔEx2 protein failed to robustly induce muscle-specific genes, and its ectopic expression conferred a selective advantage in cultured fibroblasts and an RMS xenograft. In summary, we present previously unrecognized exon skipping within MYOD1 and MYF5 in RMS, and we propose that alternative splicing can represent a mechanism to alter the function of these two transcription factors in RMS.
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Affiliation(s)
- Erin Butler
- University of Texas Southwestern Medical Center;
| | - Lin Xu
- University of Texas Southwestern Medical Center
| | | | | | | | - Lei Guo
- University of Texas Southwestern Medical Center
| | - Jiwoon Kim
- University of Texas Southwestern Medical Center
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Park JS, Kim JI, Lim HJ, Ryu SK, Kwon E, Han KM, Nam KT, Lee HW, Kang BC. Differential manifestation of ocular phenotypes in TALEN-mediated p19 arf knockout FVB/N and C57BL/6J mouse lines. Genes Genomics 2020; 42:1023-1033. [PMID: 32712838 DOI: 10.1007/s13258-020-00959-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/09/2020] [Indexed: 11/29/2022]
Abstract
BACKGROUND p19arf, primarily known as a tumor suppressor, has also been reported to play an essential role in normal development of mouse eyes. Consistently, lack of p19arf has been associated with ocular defects, but the mixed background of the knockout (KO) mouse strain used raised a concern on the accuracy of the phenotypes observed in association with the targeted gene due to genetic heterogeneity. OBJECT We carried out a study to investigate into the effect of genetic background on the manifestation of p19arf KO associated phenotypes. METHODS We characterized the phenotypes of novel p19arf KO mouse lines generated in FVB/N and C57BL/6J using a transcription activator-like effector nuclease (TALEN) system in comparison to the reported phenotypes of three other p19arf-deficient mouse lines generated using homologous recombination. RESULTS Ninety-five percent of FVB/N-p19arf KO mice showed ocular opacity from week 4 after birth which worsened rapidly until week 6, while such abnormality was absent in C57BL/6J-p19arf KO mice up to the age of 26 weeks. Histopathological analysis revealed retrolental masses and dysplasia in the retinal layer in FVB/N-p19arf KO mice from week 4. Besides these, both strains developed normally from birth to week 26 without increased tumorigenesis except for a subcutaneous tumor found in a C57BL/6J-p19arf KO mouse. CONCLUSION Our findings demonstrated surprisingly variable manifestation of p19arf-linked phenotypes between FVB/N and C57BL/6J mice, and furthermore between our mouse lines and the established lines, indicating a critical impact of genetic background on functional study of genes using gene targeting strategies in mice.
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Affiliation(s)
- Jin-Sung Park
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Joo-Il Kim
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea.,Graduate School of Translational Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hyun-Jin Lim
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea.,Graduate School of Translational Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Soo-Kyung Ryu
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Euna Kwon
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Kang-Min Han
- Graduate School of Translational Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Pathology, Dongguk University Ilsan Hospital, Goyang, Republic of Korea
| | - Ki-Taek Nam
- College of Medicine Severance Biomedical Science Institute, Yonsei University, Seoul, Republic of Korea
| | - Han-Woong Lee
- Department of Biochemistry, Yonsei University, Seoul, Republic of Korea
| | - Byeong-Cheol Kang
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea. .,Graduate School of Translational Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea. .,Biomedical Center for Animal Resource and Development, Seoul National University College of Medicine, Seoul, Republic of Korea. .,Designed Animal Resource Center, Institute of GreenBio Science and Technology, Seoul National University, Pyeongchang-gun, Gangwon-do, Republic of Korea.
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Small mitochondrial Arf (smArf) protein corrects p53-independent developmental defects of Arf tumor suppressor-deficient mice. Proc Natl Acad Sci U S A 2017; 114:7420-7425. [PMID: 28652370 DOI: 10.1073/pnas.1707292114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mouse p19Arf (human p14ARF) tumor suppressor protein, encoded in part from an alternative reading frame of the Ink4a (Cdkn2a) gene, inhibits the Mdm2 E3 ubiquitin ligase to activate p53. Arf is not expressed in most normal tissues of young mice but is induced by high thresholds of aberrant hyperproliferative signals, thereby activating p53 in incipient tumor cells that have experienced oncogene activation. The single Arf mRNA encodes two distinct polypeptides, including full-length p19Arf and N-terminally truncated and unstable p15smArf ("small mitochondrial Arf") initiated from an internal in-frame AUG codon specifying methionine-45. Interactions of p19Arf with Mdm2, or separately with nucleophosmin (NPM, B23) that localizes and stabilizes p19Arf within the nucleolus, require p19Arf N-terminal amino acids that are not present within p15smArf We have generated mice that produce either smARF alone or M45A-mutated (smArf-deficient) full-length p19Arf proteins. BCR-ABL-expressing pro/pre-B cells producing smArf alone are as oncogenic as their Arf-null counterparts in generating acute lymphoblastic leukemia when infused into unconditioned syngeneic mice. In contrast, smArf-deficient cells from mice of the ArfM45A strain are as resistant as wild-type Arf+/+ cells to comparable oncogenic challenge and do not produce tumors. Apart from being prone to tumor development, Arf-null mice are blind, and their male germ cells exhibit defects in meiotic maturation and sperm production. Although ArfM45A mice manifest the latter defects, smArf alone remarkably rescues both of these p53-independent developmental phenotypes.
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