ORIGINAL ARTICLE The CTSC-RAB38 Fusion Transcript Is Associated With the Risk of Hemorrhage in Brain Arteriovenous Malformations Zihan Yan, MD, Guangming Fan, MD, Hao Li, MD, Yuming Jiao, MD, Weilun Fu, MD, Jiancong Weng, MD, Ran Huo, MD, Jie Wang, MD, Hongyuan Xu, MD, Shuo Wang, MD, PhD, Yong Cao, MD, PhD, and Jizong Zhao, MD, PhD Abstract Brain arteriovenous malformations (bAVMs) are congenital anomalies of blood vessels that cause intracranial hemorrhage in children and young adults. Chromosomal rearrangements and fusion genes play an important role in tumor pathogenesis, though the role of fusion genes in bAVM pathophysiological processes is unclear. The aim of this study was to identify fusion transcripts in bAVMs and analyze their effects. To identify fusion transcripts associated with bAVM, RNA sequencing was performed on 73 samples, in- cluding 66 bAVM and 7 normal cerebrovascular samples, followed by STAR-Fusion analysis. Reverse transcription polymerase chain reaction and Sanger sequencing were applied to verify fusion tran- scripts. Functional pathway analysis was performed to identify po- tential effects of different fusion types. A total of 21 fusion transcripts were detected. Cathepsin C (CTSC)-Ras-Related Protein Rab-38 (RAB38) was the most common fusion and was detected in 10 of 66 (15%) bAVM samples. In CTSC-RAB38 fusion-positive samples, CTSC and RAB38 expression was significantly increased and activated immune/inflammatory signaling. Clinically, CTSC- RAB38 fusion bAVM cases had a higher hemorrhage rate than non- CTSC-RAB38 bAVM cases (p < 0.05). Our study identified recur- rent CTSC-RAB38 fusion transcripts in bAVMs, which may be asso- ciated with bAVM hemorrhage by promoting immune/inflammatory signaling. Key Words: CTSC-RAB38, Fusion transcript, Gene expression, In- tracranial arteriovenous malformations, Transcriptome sequencing. INTRODUCTION Brain arteriovenous malformations (bAVMs) are con- genital anomalies of the blood vessels that connect arteries and veins directly without intervening capillary beds (1). There is an annual detection rate of 1.3 per 1 00 000 persons for bAVMs, which cause intracranial hemorrhage in children and young adults (2, 3). Chromosomal rearrangements and fusion genes play an important role in disease pathogenesis by producing fusion transcripts and fusion proteins (4–6). However, the role of fu- sion genes in bAVM pathophysiological processes is unclear. Recent advances in high-throughput sequencing have enabled mapping of complete genetic variation on a genome- wide scale. Furthermore, transcriptome sequencing (RNA- Seq) is a revolutionary tool for the comprehensive study of all transcripts and has the features of identifying variation in gene structure, such as gene fusion (7). In this study, transcriptome sequencing was performed on 73 samples, including 66 BAVM and 7 normal cerebrovas- cular samples, to identify new fusion transcripts in bAVM. We also performed functional pathway analysis to assess the potential effects of different fusion types and analyzed the clinical significance of these fusion genes in bAVM. Our find- ings provide evidence with regard to the mechanisms underly- ing bAVMs from a novel perspective. From the Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University (ZY, GF, HL, YJ, WF, JW, RH, JW, HX, SW, YC, JZ); China National Clinical Research Center for Neurological Diseases (ZY, GF, HL, YJ, WF, JW, RH, JW, HX, SW, YC, JZ); Center of Stroke, Beijing Institute for Brain Disorders (ZY, GF, HL, YJ, WF, JW, RH, JW, HX, SW, YC, JZ); Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease (ZY, GF, HL, YJ, WF, JW, RH, JW, HX, SW, YC, JZ); Chaoyang Central Hospital, Liaoning Province, China (GF); and Savaid Medical School, University of the Chinese Academy of Scien- ces (JZ), Beijing, China. Send correspondence to: Yong Cao, MD, PhD, Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, 119 South Fourth Ring Road West, Fengtai District, Beijing 100071, China; E-mail: caoyong@bjtth.org Zihan Yan and Guangming Fan contributed equally to this work. This study was supported by the “National Key Research and Development Program of China during the 13th Five-Year Plan Period” (Grant No. 2016YFC1301803, Principle Investigator: Professor Yong Cao and Grant No. 2016YFC1301801, Principle Investigator: Professor Shuo Wang) and the “Key Project of Beijing Municipal Science & Technology Commission” (Grant No. D161100003816006, Principal Investigator: Professor Shuo Wang and Grant No. D161100003816005, Principle In- vestigator: Professor Jizong Zhao) and the “Genomics Platform Con- struction for Chinese Major Brain Disease-AVM” (Grant No. 2060335- 5, Principle Investigator: Professor Yong Cao). The authors have no duality or conflicts of interest to declare. Supplementary Data can be found at academic.oup.com/jnen. 71 V C 2020 American Association of Neuropathologists, Inc. All rights reserved. J Neuropathol Exp Neurol Vol. 80, No. 1, January 2021, pp. 71–78 doi: 10.1093/jnen/nlaa126 Downloaded from https://academic.oup.com/jnen/article/80/1/71/5943223 by guest on 13 April 2023