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Stefancsik R, Randall JD, Mao C, Sarkar S. Structure and sequence of the human fast skeletal troponin T (TNNT3) gene: insight into the evolution of the gene and the origin of the developmentally regulated isoforms. Comp Funct Genomics 2010; 4:609-25. [PMID: 18629027 PMCID: PMC2447309 DOI: 10.1002/cfg.343] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2003] [Revised: 09/24/2003] [Accepted: 10/06/2003] [Indexed: 11/21/2022] Open
Abstract
We describe the cloning, sequencing and structure of the human fast skeletal troponin T (TNNT3) gene located on chromosome 11p15.5. The single-copy gene encodes 19
exons and 18 introns. Eleven of these exons, 1–3, 9–15 and 18, are constitutively
spliced, whereas exons 4–8 are alternatively spliced. The gene contains an additional
subset of developmentally regulated and alternatively spliced exons, including a foetal
exon located between exon 8 and 9 and exon 16 or α (adult) and 17 or β (foetal and
neonatal). Exon phasing suggests that the majority of the alternatively spliced exons
located at the 5′ end of the gene may have evolved as a result of exon shuffling, because
they are of the same phase class. In contrast, the 3′ exons encoding an evolutionarily
conserved heptad repeat domain, shared by both TnT and troponin I (TnI), may be
remnants of an ancient ancestral gene. The sequence of the 5′ flanking region shows
that the putative promoter contains motifs including binding sites for MyoD, MEF-2
and several transcription factors which may play a role in transcriptional regulation
and tissue-specific expression of TnT. The coding region of TNNT3 exhibits strong
similarity to the corresponding rat sequence. However, unlike the rat TnT gene,
TNNT3 possesses two repeat regions of CCA and TC. The exclusive presence of
these repetitive elements in the human gene indicates divergence in the evolutionary
dynamics of mammalian TnT genes. Homologous muscle-specific splicing enhancer
motifs are present in the introns upstream and downstream of the foetal exon, and
may play a role in the developmental pattern of alternative splicing of the gene. The
genomic correlates of TNNT3 are relevant to our understanding of the evolution and
regulation of expression of the gene, as well as the structure and function of the protein
isoforms. The nucleotide sequence of TNNT3 has been submitted to EMBL/GenBank
under Accession No. AF026276.
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Affiliation(s)
- Raymund Stefancsik
- Department of Anatomy and Cellular Biology, Tufts University, Health Science Campus, 136 Harrison Avenue, Boston, MA 02111, USA
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Chaudhuri T, Mukherjea M, Sachdev S, Randall JD, Sarkar S. Role of the fetal and alpha/beta exons in the function of fast skeletal troponin T isoforms: correlation with altered Ca2+ regulation associated with development. J Mol Biol 2005; 352:58-71. [PMID: 16081096 DOI: 10.1016/j.jmb.2005.06.066] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 06/17/2005] [Accepted: 06/29/2005] [Indexed: 12/01/2022]
Abstract
In mammalian fast skeletal muscle, constitutive and alternative splicing from a single troponin T (TnT) gene produce multiple developmentally regulated and tissue specific TnT isoforms. Two exons, alpha (exon 16) and beta (exon 17), located near the 3' end of the gene and coding for two different 14 amino acid residue peptides are spliced in a mutually exclusive manner giving rise to the adult TnTalpha and the fetal TnTbeta isoforms. In addition, an acidic peptide coded by a fetal (f) exon located between exons 8 and 9 near the 5' end of the gene, is specifically present in TnTbeta and absent in the adult isoforms. To define the functional role of the f and alpha/beta exons, we constructed combinations of TnT cDNAs from a single human fetal fast skeletal TnTbeta cDNA clone in order to circumvent the problem of N-terminal sequence heterogeneity present in wild-type TnT isoforms, irrespective of the stage of development. Nucleotide sequences of these constructs, viz. TnTalpha, TnTalpha + f, TnTbeta - f and TnTbeta are identical, except for the presence or absence of the alpha or beta and f exons. Our results, using the recombinant TnT isoforms in different functional in vitro assays, show that the presence of the f peptide in the N-terminal T1 region of TnT, has a strong inhibitory effect on binary interactions between TnT and other thin filament proteins, TnI, TnC and Tm. The presence of the f peptide led to reduced Ca2+-dependent ATPase activity in a reconstituted thin filament, whereas the contribution of the alpha and beta peptides in the biological activity of TnT was primarily modulatory. These results indicate that the f peptide confers an inhibitory effect on the biological function of fast skeletal TnT and this can be correlated with changes in the Ca2+ regulation associated with development in fast skeletal muscle.
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Affiliation(s)
- Tathagata Chaudhuri
- Program in Cell, Molecular and Developmental Biology, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA 02111, USA
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Davoli R, Fontanesi L, Braglia S, Russo V. The porcine fast skeletal muscle troponin T3 (TNNT3) gene: identification of mutations and linkage mapping to chromosome 2. Anim Genet 2004; 34:391-2. [PMID: 14510683 DOI: 10.1046/j.1365-2052.2003.01046.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- R Davoli
- DIPROVAL, Sezione di Allevamenti Zootecnici, Faculty of Agriculture, University of Bologna, Via F.lli Rosselli 107, Villa Levi - Coviolo, 42100 Reggio Emilia, Italy.
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Bottinelli R, Reggiani C. Human skeletal muscle fibres: molecular and functional diversity. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2001; 73:195-262. [PMID: 10958931 DOI: 10.1016/s0079-6107(00)00006-7] [Citation(s) in RCA: 345] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Contractile and energetic properties of human skeletal muscle have been studied for many years in vivo in the body. It has been, however, difficult to identify the specific role of muscle fibres in modulating muscle performance. Recently it has become possible to dissect short segments of single human muscle fibres from biopsy samples and make them work in nearly physiologic conditions in vitro. At the same time, the development of molecular biology has provided a wealth of information on muscle proteins and their genes and new techniques have allowed analysis of the protein isoform composition of the same fibre segments used for functional studies. In this way the histological identification of three main human muscle fibre types (I, IIA and IIX, previously called IIB) has been followed by a precise description of molecular composition and functional and biochemical properties. It has become apparent that the expression of different protein isoforms and therefore the existence of distinct muscle fibre phenotypes is one of the main determinants of the muscle performance in vivo. The present review will first describe the mechanisms through which molecular diversity is generated and how fibre types can be identified on the basis of structural and functional characteristics. Then the molecular and functional diversity will be examined with regard to (1) the myofibrillar apparatus; (2) the sarcolemma and the sarcoplasmic reticulum; and (3) the metabolic systems devoted to producing ATP. The last section of the review will discuss the advantage that fibre diversity can offer in optimizing muscle contractile performance.
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Affiliation(s)
- R Bottinelli
- Institute of Human Physiology, University of Pavia, Via Forlanni 6, 27100, Pavia, Italy.
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Abstract
Three troponin I genes have been identified in vertebrates that encode the isoforms expressed in adult cardiac muscle (TNNI3), slow skeletal muscle (TNNI1) and fast skeletal muscle (TNNI2), respectively. While the organization and regulation of human cardiac and slow skeletal muscle genes have been investigated in detail, the fast skeletal troponin I gene has to date only been examined in birds. Here, we describe the structure and complete sequence of the human fast skeletal muscle troponin I gene (TNNI2) and identify putative regulatory elements within both the 5' flanking region and the first intron. In particular, a region containing MEF-2, E-box, CCAC and CAGG elements was identified in intron 1 that closely resembles the fast internal regulatory element (FIRE) of the quail intronic enhancer. We have previously shown that the fast skeletal muscle troponin I gene is located at 11p15.5 and noted potential close linkage with the fast skeletal muscle troponin T gene (TNNT3). Here, we have isolated two independent human PAC genomic clones that contain either TNNI2 or TNNT3 and demonstrate by interphase FISH mapping that they are less than 100 kb apart in the genome. The results demonstrate that the human TNNI2 gene is closely related to its avian counterparts with conserved elements within both the putative promoter and first intron. Our data further confirm close physical linkage of TNNI2 and TNNI3 on 11p15.5.
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Affiliation(s)
- A J Mullen
- Imperial College School of Medicine, National Heart and Lung Institute, London, UK
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Barton PJ, Cullen ME, Townsend PJ, Brand NJ, Mullen AJ, Norman DA, Bhavsar PK, Yacoub MH. Close physical linkage of human troponin genes: organization, sequence, and expression of the locus encoding cardiac troponin I and slow skeletal troponin T. Genomics 1999; 57:102-9. [PMID: 10191089 DOI: 10.1006/geno.1998.5702] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Based on chromosomal mapping data, we recently revealed an unexpected linkage of troponin genes in the human genome: the six genes encoding striated muscle troponin I and troponin T isoforms are located at three chromosomal sites, each of which carries a troponin I-troponin T gene pair. Here we have investigated the organization of these genes at the DNA level in isolated P1 and PAC genomic clones and demonstrate close physical linkage in two cases through the isolation of individual clones containing a complete troponin I-troponin T gene pair. As an initial step toward fully characterizing this pattern of linkage, we have determined the organization and complete sequence of the locus encoding cardiac troponin I and slow skeletal troponin T and thereby also provide the first determination of the structure and sequence of a slow skeletal troponin T gene. Our data show that the genes are organized head to tail and are separated by only 2.6 kb of intervening sequence. In contrast to other troponin genes, and despite their close proximity, the cardiac troponin I and slow skeletal troponin T genes show independent tissue-specific expression. Such close physical linkage has implications for the evolution of the troponin gene families, for their regulation, and for the analysis of mutations implicated in cardiomyopathy.
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Affiliation(s)
- P J Barton
- Imperial College School of Medicine, National Heart and Lung Institute, Dovehouse Street, London, SW3 6LY, United Kingdom.
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Koch A, Juan TS, Jenkins NA, Gilbert DJ, Copeland NG, McNiece IK, Fletcher FA. cDNA cloning and chromosomal mapping of mouse fast skeletal muscle troponin T. Mamm Genome 1997; 8:346-8. [PMID: 9107680 DOI: 10.1007/s003359900437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- A Koch
- Department of Developmental Hematology, Amgen, Incorporated, M/S99-1-A, 1840 De Havilland Drive Thousand Oaks, California 91320-1789, USA
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Tiso N, Rampoldi L, Pallavicini A, Zimbello R, Pandolfo D, Valle G, Lanfranchi G, Danieli GA. Fine mapping of five human skeletal muscle genes: alpha-tropomyosin, beta-tropomyosin, troponin-I slow-twitch, troponin-I fast-twitch, and troponin-C fast. Biochem Biophys Res Commun 1997; 230:347-50. [PMID: 9016781 DOI: 10.1006/bbrc.1996.5958] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In this paper the chromosomal localization of the human skeletal muscle genes Troponin-I slow-twitch (TNNI1), Troponin-I fast-twitch (TNNI2), and Troponin-C fast (TNNC2) and the refinement of the position for alpha-Tropomyosin (TPM1) and beta-Tropomyosin (TPM2) are reported. By radiation hybrid mapping, TPM1 was assigned to chromosome 15q22.1, TPM2 to chromosome 9p13.2-p13.1, TNNI1 to chromosome 1q31.3, TNNI2 to chromosome 11p15.5, and TNNC2 to chromosome 20q12-q13.11. The genomic distribution of these genes is discussed, with particular emphasis on the cluster organization of the Troponin genes.
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MESH Headings
- Base Sequence
- Chromosome Mapping
- Chromosomes, Human, Pair 1
- Chromosomes, Human, Pair 11
- Chromosomes, Human, Pair 15
- Chromosomes, Human, Pair 20
- Chromosomes, Human, Pair 9
- DNA Primers
- Humans
- Molecular Sequence Data
- Multigene Family
- Muscle Fibers, Fast-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle, Skeletal/metabolism
- Polymerase Chain Reaction
- Tropomyosin/biosynthesis
- Tropomyosin/genetics
- Troponin C/biosynthesis
- Troponin C/genetics
- Troponin I/biosynthesis
- Troponin I/genetics
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Affiliation(s)
- N Tiso
- Biology Department, University of Padova, Italy
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