PUBLICATION

Heart-specific isoform of tropomyosin4 is essential for heartbeat in zebrafish embryos

Authors

Zhao, L., Zhao, X., Tian, T., Lu, Q., Skrbo-Larssen, N., Wu, D., Kuang, Z., Zheng, X., Han, Y., Yang, S., Zhang, C., and Meng, A.

ID

ZDB-PUB-080630-18

Date

2008

Source

Cardiovascular research 80(2): 200-208 (Journal)

Registered Authors

Meng, Anming, Tian, Tian, Zhao, Long, Zhao, Xinyi

Keywords

zebrafish, heart, tropomyosin, transposon, thin filament

MeSH Terms

Animals, Genetically Modified
Zebrafish*/embryology
Zebrafish*/genetics
Zebrafish*/metabolism
DNA Transposable Elements
Homozygote
Animals
Sarcomeres/metabolism
Mutation
Heart Rate*/genetics
Myocardium/metabolism*
Myocardium/ultrastructure
Gene Expression Regulation, Developmental*
Gene Knockdown Techniques
Blood Vessels/embryology
Blood Vessels/metabolism
Heart/embryology*
Tropomyosin/genetics
Tropomyosin/metabolism*
Mutagenesis, Insertional
Phenotype
Zebrafish Proteins/genetics
Zebrafish Proteins/metabolism*
Protein Isoforms

(all 24)

PubMed

18583338 Full text @ Cardiovasc. Res.

Abstract

Aim: Tropomyosin (Tpm) proteins, encoded by four Tpm genes (Tpm1-4), are associated with the stabilization of the F-actin filaments and play important roles in modulating muscle contraction. So far, little is known about Tpm4 function in embryonic heart development and its involvement in the cardiovascular diseases. In this study, we investigated functions of different isoforms of tpm4 in embryonic heartbeat in zebrafish. Methods and Results: The transgenic zebrafish line, T2EGEZ8, was generated by insertion of a Tol2 transposon gene trap vector, and homozygous mutants (T2EGEZ8(m/m)) of this line showed failure of embryonic heartbeat without other detectable phenotypes. Observation by transmission electron microscopy revealed that the ventricular myocytes of mutant fish contained fewer, disorganized myofibrillar filaments. The transposon genome in T2EGEZ8 fish was found by tail-PCR and RT-PCR to have inserted into the 9th intron of the tpm4 locus, which resulted in production of Tpm4-GFP fusion proteins and loss of normal transcripts tpm4-tv1 and tpm4-tv2. Whole-mount in situ hybridization indicated that tpm4-tv1, encoding a peptide of 284 residues, is specifically expressed in the heart of zebrafish embryos while tpm4-tv2, encoding a peptide of 248 residues, is mainly present in the vasculature but absent in the heart. Knockdown of tpm4-tv1 and tpm4-tv2 within wild-type embryos led to the failure of heartbeat, which could be rescued by coinjection with tpm4-tv1 mRNA but not with tpm4-tv2 mRNA. Conclusion: Tpm4-tv1 is a heart-specific isoform of Tpm4 and is essential for heartbeat in zebrafish embryos.

Genes / Markers

Probes

Figures

Show all Figures

Expression

Gene	Fish	Conditions	Stage	Anatomy	Assay	Figure
EGFP	tpm4a^zf152Gt/+	standard conditions	Day 5	aortic arch	IFL	Fig. 1
EGFP	tpm4a^zf152Gt/+	standard conditions	Long-pec	atrium	IFL	Fig. 1
EGFP	tpm4a^zf152Gt/+	standard conditions	Long-pec	cardiac ventricle	IFL	Fig. 1
EGFP	tpm4a^zf152Gt/+	standard conditions	Prim-25	cardinal system	IFL	Fig. 1
EGFP	tpm4a^zf152Gt/+	standard conditions	Prim-25	dorsal aorta	IFL	Fig. 1
EGFP	tpm4a^zf152Gt/+	standard conditions	Long-pec	dorsal aorta	IFL	Fig. 1
EGFP	tpm4a^zf152Gt/+	standard conditions	Prim-25	floor plate	IFL	Fig. 1
EGFP	tpm4a^zf152Gt/+	standard conditions	Long-pec	floor plate	IFL	Fig. 1
EGFP	tpm4a^zf152Gt/+	standard conditions	14-19 somites	head	IFL	Fig. 1
EGFP	tpm4a^zf152Gt/+	standard conditions	Prim-25	horizontal myoseptum	IFL	Fig. 1

1 - 10 of 110

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Phenotype

Fish	Conditions	Stage	Phenotype	Figure
WT + MO5-tpm4a	standard conditions	Long-pec	blood circulation arrested, abnormal	Fig. 5
WT + MO5-tpm4a	standard conditions	Long-pec	cardiac muscle contraction arrested, abnormal	Fig. 5
WT + MO5-tpm4a	standard conditions	Long-pec	eye decreased size, abnormal	Fig. 5
WT + MO5-tpm4a	standard conditions	Long-pec	heart contraction arrested, abnormal	Fig. 5
WT + MO5-tpm4a	standard conditions	Long-pec	heart edematous, abnormal	Fig. 5
tpm4a^{zf152Gt/zf152Gt}	standard conditions	Protruding-mouth	cardiac muscle cell myofibril decreased amount, abnormal	Fig. 6
tpm4a^{zf152Gt/zf152Gt}	standard conditions	Protruding-mouth	cardiac muscle cell sarcomere disorganized, abnormal	Fig. 6
tpm4a^{zf152Gt/zf152Gt}	standard conditions	Protruding-mouth	cardiac muscle cell Z disc absent, abnormal	Fig. 6
tpm4a^{zf152Gt/zf152Gt}	standard conditions	Protruding-mouth	cardiac ventricle myofibril disorganized, abnormal	Fig. 6
tpm4a^{zf152Gt/zf152Gt}	standard conditions	Day 5	cardiac muscle cell myofibril decreased amount, abnormal	Fig. 6

1 - 10 of 13

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Mutations / Transgenics

Allele	Construct	Type	Affected Genomic Region
la4Tg	Tg(kdrl:RFP)	Transgenic Insertion
zf152Gt	Gt(T2EGE)	Transgenic Insertion	tpm4a

Human Disease / Model

Sequence Targeting Reagents

Target	Reagent	Reagent Type
tpm4a	MO1-tpm4a	MRPHLNO
tpm4a	MO2-tpm4a	MRPHLNO
tpm4a	MO3-tpm4a	MRPHLNO
tpm4a	MO4-tpm4a	MRPHLNO
tpm4a	MO5-tpm4a	MRPHLNO

Fish

Fish
tpm4a^zf152Gt/+
tpm4a^zf152Gt/+; la4Tg
tpm4a^{zf152Gt/zf152Gt}
tpm4a^{zf152Gt/zf152Gt}; la4Tg
tpm4a^{zf152Gt/zf152Gt} + MO5-tpm4a
WT
WT + MO5-tpm4a

Antibodies

Orthology

Engineered Foreign Genes

Marker	Marker Type	Name
EGFP	EFG	EGFP
RFP	EFG	RFP

Mapping

Zhao et al., 2008 ZDB-PUB-080630-18 PMID:18583338

Heart-specific isoform of tropomyosin4 is essential for heartbeat in zebrafish embryos

Zhao et al., 2008

ZDB-PUB-080630-18
PMID:18583338