title: An internal promoter underlies the difference in disease severity between N- and C-terminal truncation mutations of Titin in zebrafish.
abstract: Truncating mutations in the giant sarcomeric protein Titin result in dilated cardiomyopathy and skeletal myopathy. The most severely affected dilated cardiomyopathy patients harbor Titin truncations in the C-terminal two-thirds of the protein, suggesting that mutation position might influence disease mechanism. Using CRISPR/Cas9 technology, we generated six zebrafish lines with Titin truncations in the N-terminal and C-terminal regions. Although all exons were constitutive, C-terminal mutations caused severe myopathy whereas N-terminal mutations demonstrated mild phenotypes. Surprisingly, neither mutation type acted as a dominant negative. Instead, we found a conserved internal promoter at the precise position where divergence in disease severity occurs, with the resulting protein product partially rescuing N-terminal truncations. In addition to its clinical implications, our work may shed light on a long-standing mystery regarding the architecture of the sarcomere.
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Diana
authors.initials: D
authors.lastname: Tran
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Mai
authors.initials: M
authors.lastname: Baalbaki
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Ling Fung
authors.initials: LF
authors.lastname: Tang
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Annie
authors.initials: A
authors.lastname: Poon
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Angelo
authors.initials: A
authors.lastname: Pelonero
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Erron W
authors.identifier: http://orcid.org/0000-0001-6868-9121
authors.initials: EW
authors.lastname: Titus
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Christiana
authors.initials: C
authors.lastname: Yuan
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Chenxu
authors.initials: C
authors.lastname: Shi
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Shruthi
authors.initials: S
authors.lastname: Patchava
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Halper
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Jasmine
authors.initials: J
authors.lastname: Garg
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Irina
authors.initials: I
authors.lastname: Movsesyan
authors.affiliation: Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, United States.|McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, United States.
authors.forename: Chaoying
authors.initials: C
authors.lastname: Yin
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.|Department of Medicine, University of California, San Francisco, San Francisco, United States.
authors.forename: Roland
authors.initials: R
authors.lastname: Wu
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.|Department of Medicine, University of California, San Francisco, San Francisco, United States.
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Wilsbacher
authors.affiliation: Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, United States.|McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, United States.
authors.forename: Jiandong
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Exercise Sciences, Brigham Young University, Provo, United States.
authors.forename: Ronald L
authors.identifier: http://orcid.org/0000-0002-5128-4635
authors.initials: RL
authors.lastname: Hager
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.|Department of Medicine, University of California, San Francisco, San Francisco, United States.
authors.forename: Shaun R
authors.initials: SR
authors.lastname: Coughlin
authors.affiliation: Department of Biochemistry, University of Zurich, Zurich, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Jinek
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.|Department of Physiological Nursing, University of California, San Francisco, San Francisco, United States.
authors.forename: Clive R
authors.initials: CR
authors.lastname: Pullinger
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.|Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.
authors.forename: John P
authors.initials: JP
authors.lastname: Kane
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.|Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Hart
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.|Department of Dermatology, University of California, San Francisco, San Francisco, United States.|Institute for Human Genetics, University of California, San Francisco, United States.
authors.forename: Pui-Yan
authors.initials: PY
authors.lastname: Kwok
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.|Department of Medicine, University of California, San Francisco, San Francisco, United States.|Institute for Human Genetics, University of California, San Francisco, United States.|California Institute for Quantitative Biosciences, San Francisco, United States.
authors.forename: Rahul C
authors.initials: RC
authors.lastname: Deo
mesh_terms: D000818:Animals; D002311:Cardiomyopathy, Dilated / Q000473:pathology*; D064211:Connectin / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D006801:Humans; D009135:Muscular Diseases / Q000473:pathology*; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion; D015027:Zebrafish
chemical_list: D064211:Connectin; D050505:Mutant Proteins
keywords: cardiomyopathy; genetics; human; human biology; medicine; mouse; sarcomere; zebrafish