Myofibrillogenesis in the developing zebrafish heart: A functional study of tnnt2

Various hypotheses have been proposed to explain the molecule processes of sarcomere assembly, partially due to the lack of systematic genetic studies of sarcomeric genes in an in vivo model. Towards the goal of developing zebrafish as a vertebrate model for this purpose, we characterized myofibrill...

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Bibliographic Details
Published in:Developmental biology 2009-07, Vol.331 (2), p.237-249
Main Authors: Huang, Wei, Zhang, Ruilin, Xu, Xiaolei
Format: Article
Language:English
Subjects:
Actin Cytoskeleton - physiology
Animals
Danio rerio
Freshwater
Heart
Heart - embryology
Models, Animal
Myocardium - metabolism
Myocytes, Cardiac - cytology
Myocytes, Cardiac - physiology
Myofibrillogenesis
Myofibrils - physiology
Myosins - physiology
Sarcomere
Sarcomeres - physiology
Tnnt2
Troponin T - physiology
Zebrafish
Zebrafish - embryology
Zebrafish - physiology
Zebrafish Proteins - physiology
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Summary:Various hypotheses have been proposed to explain the molecule processes of sarcomere assembly, partially due to the lack of systematic genetic studies of sarcomeric genes in an in vivo model. Towards the goal of developing zebrafish as a vertebrate model for this purpose, we characterized myofibrillogenesis in a developing zebrafish heart and went on to examine the functions of cardiac troponin T (tnnt2). We found that sarcomere assembly in zebrafish heart was initiated from a non-striated actin filament network at the perimembrane region, whereas sarcomeric myosin is independently assembled into thick filaments of variable length before integrating into the thin filament network. Compared to Z-discs that are initially aligned to form shorter periodic dots and expanded longitudinally at a later time, M-lines assemble later and have a constant length. Depletion of full-length tnnt2 disrupted the striation of thin filaments and Z-bodies, which sequentially affects the striation of thick filaments and M-lines. Conversely, truncation of a C-terminal troponin complex-binding domain did not affect the striation of these sarcomere sub-structures, but resulted in reduced cardiomyocyte size. In summary, our data indicates that zebrafish are a valuable in vivo model for studying both myofibrillogenesis and sarcomere-based cardiac diseases.
ISSN:0012-1606
1095-564X
DOI:10.1016/j.ydbio.2009.04.039