A modifier screen identifies DNAJB6 as a cardiomyopathy susceptibility gene
Yonghe Ding, Pamela A. Long, J. Martijn Bos, Yu-Huan Shih, Xiao Ma, Rhianna S. Sundsbak, Jianhua Chen, Yiwen Jiang, Liqun Zhao, Xinyang Hu, Jianan Wang, Yongyong Shi, Michael J. Ackerman, Xueying Lin, Stephen C. Ekker, Margaret M. Redfield, Timothy M. Olson, Xiaolei Xu
Yonghe Ding, Pamela A. Long, J. Martijn Bos, Yu-Huan Shih, Xiao Ma, Rhianna S. Sundsbak, Jianhua Chen, Yiwen Jiang, Liqun Zhao, Xinyang Hu, Jianan Wang, Yongyong Shi, Michael J. Ackerman, Xueying Lin, Stephen C. Ekker, Margaret M. Redfield, Timothy M. Olson, Xiaolei Xu
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Research Article Cardiology Genetics

A modifier screen identifies DNAJB6 as a cardiomyopathy susceptibility gene

Abstract

Mutagenesis screening is a powerful forward genetic approach that has been successfully applied in lower-model organisms to discover genetic factors for biological processes. This phenotype-based approach has yet to be established in vertebrates for probing major human diseases, largely because of the complexity of colony management. Herein, we report a rapid strategy for identifying genetic modifiers of cardiomyopathy (CM). Based on the application of doxorubicin stress to zebrafish insertional cardiac (ZIC) mutants, we identified 4 candidate CM-modifying genes, of which 3 have been linked previously to CM. The long isoform of DnaJ (Hsp40) homolog, subfamily B, member 6b (dnajb6b(L)) was identified as a CM susceptibility gene, supported by identification of rare variants in its human ortholog DNAJB6 from CM patients. Mechanistic studies indicated that the deleterious, loss-of-function modifying effects of dnajb6b(L) can be ameliorated by inhibition of ER stress. In contrast, overexpression of dnajb6(L) exerts cardioprotective effects on both fish and mouse CM models. Together, our findings establish a mutagenesis screening strategy that is scalable for systematic identification of genetic modifiers of CM, feasible to suggest therapeutic targets, and expandable to other major human diseases.

Authors

Yonghe Ding, Pamela A. Long, J. Martijn Bos, Yu-Huan Shih, Xiao Ma, Rhianna S. Sundsbak, Jianhua Chen, Yiwen Jiang, Liqun Zhao, Xinyang Hu, Jianan Wang, Yongyong Shi, Michael J. Ackerman, Xueying Lin, Stephen C. Ekker, Margaret M. Redfield, Timothy M. Olson, Xiaolei Xu

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Figure 2

The GBT0411 mutant was tagged to the dnajb6b(L) isoform that predominantly expresses in the heart.

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The GBT0411 mutant was tagged to the dnajb6b(L) isoform that predominant...
(A) Northern blot analysis of dnajb6b(S) and dnajb6b(L) isoforms in indicated 3-month-old adult fish tissues demonstrated a predominant expression of dnajb6b(L) in the fish heart and skeletal muscle. (B) Western blot analysis (left) and quantification (right) of Dnajb6(S) and Dnajb6(L) isoforms expression in 1-year-old WT C57BL/6 mouse tissues indicated a predominant expression of Dnajb6(L) in the mouse heart. Values are presented relative to heart expression. Data represent mean ±SEM. (C) Western blot analysis (left) and quantification (right) of DNAJB6(L) and DNAJB6(S) protein expression in human heart and skeletal muscle lysates. Values are presented relative to heart expression. Data represent mean ±SEM. (D) Kaplan-Meier survival curves of indicated fish injected with a single bolus of 20 μg/gbm doxorubicin (DOX). Cardiomyocyte-specific overexpression of zebrafish dnajb6b(L) rescued DOX-induced fish death in the GBT0411 heterozygous mutant. *P < 0.05, log-rank test. Comparison of Tg(cmlc2:dnajb6b(L)-EGFP); GBT0411+/– vs. GBT0411+/–.