Induction of apoptosis and inhibition of cell growth by tbx5 knockdown contribute to dysmorphogenesis in Zebrafish embryos

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.

Zinc transporter ZIP10 forms a heteromer with ZIP6 which regulates embryonic development and cell migration

“…In addition to the phenotypic effects in common with those published for the zip6 morphant [ 4 ], knockdown of zip10 caused pericardial oedema and deformed string-shaped heart. Similar deformities in zebrafish were observed through manipulations of the zinc finger transcription factor, Tbx5 [ 67 , 68 ]. It was also shown in rats that zinc deficiency in the dam results in foetuses with heart anomalies because of the alterations in the expression and distribution of several proteins involved in its development, including human natural killer-1 (HNK-1), Connexin-43 (Cx43), survival of motor neuron 1 (SMA), GATA-4 and FOG-2 [ 69 ].…”

High expression level of T-box transcription factor 5 predicts unfavorable survival in stage I and II gastric adenocarcinoma

“…TBX5 is a member of the T-box family and is essential for the embryonic development of the forelimbs and heart ( 4 , 5 ). HOS is caused by mutations in TBX5 ( 12 ). In a previous study by Rosenbluh et al ( 9 ), it was demonstrated that TBX5 forms a complex with β-catenin and YAP1, which is essential for the process of tumorigenesis in colorectal cancer.…”

The paracrine effect of exogenous growth hormone alleviates dysmorphogenesis caused by tbx5 deficiency in zebrafish (Danio rerio) embryos

“…In our previous study, 4 control groups, including the 3' end of tbx5 -MO(2) (5’-GCCTGTACGATGTCTACCGTGAGGC-3’), mismatched tbx5 -MO (5’-GTCTCTTGACTCTCCGCGATCTCGG-3’), and embryos with blank microinjection and wild-types without microinjection, were included to identify the specific blockage of tbx5 mRNA translation effect of tbx5 -MO [9]. The efficacy and specificity of the tbx5 -MO has been confirmed in previous published articles [9,14]. …”