The molecular structures and expression patterns of zebrafish troponin I genes.
Troponin I (TnnI), a constituent of the troponin complex on the thin filament, providers a calcium-sensitive switch for striated muscle contraction. Cardiac TnnI is, therefore, a highly sensitive and specific marker of myocardial injury in acute coronary syndromes. The TnnI gene, which has been identified in birds and mammals , encodes the isoforms expressed in cardiac muscle fast skeletal muscle and slow skeletal muscle. However, very little is known about the TnnI gene in lower vertebrates. Here, we cloned and characterized the molecular structures and expression patterns of three types of zebrafish tnni genes: tnni1, tnni2, and tnn-HC (Heart and craniofacial). Based on the unrooted radial gene tree analysis of the TnnI gene among vertebrates, the zebrafish Tnni1 and TnnI2 we cloned were homologous of the slow muscle TnnI1 and fast muscle TnnI2 of other vertebrates, respectively. In addition, reverse transcription-polymerase chain reaction (RT-PCR) and whole-mount in situ hybridization demonstrated that zebrafish tnni1 and tnni2 transcripts were not detectable in the somites until 16 h post-fertilization (hpf), after which they were identified as slow-and fast muscle-specific, respectively . Interestingly, tnni-HC, a novel tnni isoform of zebrafish was expressed exclusive in heart during early cardiogenesis as 16 hpf, but then extended its expression in craniofacial muscle after 48 hpf. Thus, using zebrafish as our system model, it is suggested that the results, as noted above, may provide more insight into the molecular structure and expression pattens of the lower vertebrate TnnI gene.
Fu
Chuan-Yang
CY
Institite of Molecular and Cellular Biology, National Taiwan University, Room 307, Fisheries Science Building, No1, Section 4, Roosevelt Road, Taipei 106, Taiwan.
Lee
Hung-Chieh
HC
Tsai
Huai-Jen
HJ
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D019170:Somites / Q000378:metabolism; D013997:Time Factors; D019210:Troponin I / Q000145:classification / Q000235:genetics*; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*; D029961:Zebrafish Proteins / Q000235:genetics*
D020033:Protein Isoforms; D019210:Troponin I; D029961:Zebrafish Proteins