Induction of apoptosis and inhibition of cell growth by tbx5 knockdown contribute to dysmorphogenesis in Zebrafish embryosReport as inadecuate




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Journal of Biomedical Science

, 18:73

First Online: 08 October 2011Received: 22 May 2011Accepted: 08 October 2011DOI: 10.1186-1423-0127-18-73

Cite this article as: Lu, J., Tsai, T., Choo, S. et al. J Biomed Sci 2011 18: 73. doi:10.1186-1423-0127-18-73

Abstract

BackgroundThe tbx5 mutation in human causes Holt-Oram syndrome, an autosomal dominant condition characterized by a familial history of congenital heart defects and preaxial radial upper-limb defects. We report aberrant apoptosis and dormant cell growth over head, heart, trunk, fin, and tail of zebrafish embryos with tbx5 deficiency correspond to the dysmorphogenesis of tbx5 morphants.

MethodsWild-type zebrafish embryos at the 1-cell stage were injected with 4.3 nl of 19.4 ng of tbx5 morpholino or mismatch-tbx5-MO respectively in tbx5 morphants and mismatched control group. Semi-quantitative RT-PCR was used to for expression analysis of apoptosis and cell cycle-related genes. TUNEL and immunohistochemical assay showed the apoptosis spots within the local tissues. Ultra-structure of cardiac myocardium was examined by transmission electron microscope.

ResultsApoptosis-related genes bad, bax, and bcl2, and cell cycle-related genes cdk2, pcna, p27, and p57 showed remarkable increases in transcriptional level by RT-PCR. Using a TUNEL and immnuohistochemical assay, apoptosis was observed in the organs including the head, heart, pectoral fins, trunk, and tail of tbx5 knockdown embryos. Under transmission electron microscopic examination, mitochondria in cardiomyocytes became swollen and the myocardium was largely disorganized with a disarrayed appearance, compatible with reduced enhancement of myosin in the cardiac wall. The ATP level was reduced, and the ADP-ATP ratio as an apoptotic index significantly increased in the tbx5 deficient embryos.

ConclusionOur study highlighted that tbx5 deficiency evoked apoptosis, distributed on multiple organs corresponding to dysmorphogenesis with the shortage of promising maturation, in tbx5 knockdown zebrafish embryos. We hypothesized that mesenchymal cell apoptosis associated with altered TBX5 level may subsequently interfered with organogenesis and contributed to dysmorphogenesis in tbx5 deficiency zebrafish embryos.

Keywordszebrafish mitochondria apoptosis tbx5 Holt-Oram syndrome cell cycle Electronic supplementary materialThe online version of this article doi:10.1186-1423-0127-18-73 contains supplementary material, which is available to authorized users.

Jenher Lu and Jennkan Lu contributed equally to this work.

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Author: Jenher Lu - Tzuchun Tsai - Sielin Choo - Shuyu Yeh - Renbing Tang - Anhang Yang - Hsinyu Lee - Jennkan Lu

Source: https://link.springer.com/



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