Molecular cloning and developmental expression of human cardiac troponin T

Mesnard, Laurence; Samson, Françoise; Espinasse, Isabelle; Durane, Jacques; Neveux, Jean-Yves; Mercadier, Jean-Jacques

doi:10.1016/0014-5793(93)80981-y

Cited by 56 publications

(30 citation statements)

References 25 publications

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“…1 shows that the complete cDNA sequence of the human cardiac troponin T sequence was determined by overlapping ESTs similar to the rat cardiac troponin T transcript. This result confirmed the full-length cDNA sequence ofthe human cardiac troponin T gene, which was recently published (14 human sequence remains unknown. Tagged clones representing the putative human homologues of such genes are denoted in Table 2 by the organism from which the homologous sequence was derived (indicated in parentheses, Table 2).…”

Section: Methodssupporting

confidence: 75%

A catalogue of genes in the cardiovascular system as identified by expressed sequence tags.

Liew

Hwang

Fung

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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The heart, which is composed of all the cellular components of the circulatory system, is a representative organ for obtaining genes expressed in the cardiovascular system in normal and disease states. We used partial sequences of cDNA clones, or expressed sequence tags, to identify and tag genes expressed in this organ. More than 3500 partial sequences representing > 3000 cDNA clones have been obtained from either the 5' or 3' end of inserts derived from human heart cDNA libraries. Of 3132 cDNA clones analyzed by sequence similarity searching against the GenBank/EMBL data bases, 1485 (47.4%) were found to represent additional, previously undiscovered genes, whereas 267 clones were matched to human brain expressed sequence tags. Clones matching to known genes were catalogued according to their putative structural and cellular functions. cDNA probes from reverse-transcribed mRNAs of fetal and adult hearts were used to study differential expression of selected clones in cardiac development. Cataloguing genes expressed in the heart may provide insight into the genes involved in health and cardiovascular disease.

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Section: Methodssupporting

confidence: 75%

A catalogue of genes in the cardiovascular system as identified by expressed sequence tags.

Liew

Hwang

Fung

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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“…It would be unexpected but important if TnT modulates this kinetic step, because it would provide the possibility for physiological regulation of the unloaded shortening velocity. In this regard, the mutation site is very close to the hypervariable region of TnT that is developmentally regulated by alternative splicing mechanisms (27,(57)(58)(59). Indeed, subtle changes in actin-myosin interactions (18, 42) and the Ca 2ϩ sensitivity of muscle tension (44,46,47) are produced by amino acid sequence variations in this region, and possibly also by phosphorylation (60).…”

Section: Discussionmentioning

confidence: 99%

Altered cardiac troponin T in vitro function in the presence of a mutation implicated in familial hypertrophic cardiomyopathy.

et al. 1996

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Familial hypertrophic cardiomyopathy (HCM) can be caused by dominant missense mutations in cardiac troponin T (TnT), ␣ -tropomyosin, C-protein, or cardiac myosin heavy chain genes. The myosin mutations are known to impair function, but any functional consequences of the TnT mutations are unknown. This report describes the in vitro function of troponin containing an Ile91Asn mutation in rat cardiac TnT, corresponding to the HCM-causing Ile79Asn mutation in man. Mutant and wild-type TnT cDNAs were expressed in bacteria and the proteins purified and reconstituted with the other troponin subunits. The mutation had no effect on troponin's affinity for tropomyosin, troponininduced binding of tropomyosin to actin, cooperative binding of myosin subfragment 1 to the thin filament, Ca 2 ϩ -sensitive regulation of thin filament-myosin subfragment 1 ATPase activity, or the Ca 2 ϩ concentration dependence of this regulation. However, the mutation resulted in 50% faster thin filament movement over a surface coated with heavy meromyosin in in vitro motility assays. The increased sliding speed suggests an unexpected role for the amino terminal region of TnT in which this mutation occurs. The relationship between this faster motility and altered cardiac contraction in patients with HCM is discussed. ( J. Clin. Invest. 1996. 97:2842-2848.)

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“…In an earlier publication (18), we found that mutations R92Q and F110I (11) greatly impaired the solubility of bovine cardiac troponin. (Bovine TnT amino acids are designated in the present report, unlike some of our previous work (18,25,26), by the sequence positions of homologous human cardiac TnT residues (27).) Although it was possible to reconstitute troponin complexes containing these mutant TnTs by gradually dialyzing away denaturant under high salt conditions, R92Q troponin precipitated when the ionic strength was decreased below 0.5 M, and F110I troponin precipitated unless 10% glycerol was added in addition to a high ionic strength buffer.…”

Section: Troponin Contains a Globular Camentioning

confidence: 92%

Folding and Function of the Troponin Tail Domain

Hinkle

Tobacman

2003

Journal of Biological Chemistry

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Troponin contains a globular Ca 2؉ -binding domain and an elongated tail domain composed of the N terminus of subunit troponin T (TnT). The tail domain anchors troponin to tropomyosin and actin, modulates myosin function, and is a site of cardiomyopathy-inducing mutations. Critical interactions between tropomyosin and troponin are proposed to depend on tail domain residues 112-136, which are highly conserved across phyla. Most cardiomyopathy mutations in TnT flank this region. Three such mutations were examined and had contrasting effects on peptide TnT-(1-156), promoting folding and thermal stability assessed by circular dichroism (F110I) or weakening folding and stability (T104V and to a small extent R92Q). Folding of both TnT-(1-156) and whole troponin was promoted by replacing bovine TnT Thr-104 with human TnT Ala-104, further indicating the importance of this cardiomyopathy site residue for protein folding. Mutation F110I markedly stabilized the troponin tail but weakened binding of holo-troponin to actin-tropomyosin 8-fold, suggesting that loss of flexibility impairs troponin tail function. The effect of the F110I mutation on troponintropomyosin binding to actin was much less, indicating this flexibility is particularly important for the interactions of troponin with tropomyosin. We suggest that most cardiomyopathic mutations in the troponin tail alter muscle function indirectly, by perturbing interactions between troponin and tropomyosin requisite for the complex effects of these proteins on myosin.In striated muscles, including the heart and skeletal muscle, contraction is tightly regulated by the reversible binding of Ca 2ϩ to the thin filament protein troponin. Tight and specific attachment of troponin to the thin filament is mediated by the troponin tail domain, which is composed of the N-terminal portion of TnT 1 and interacts with the tropomyosin C terminus. Hydrodynamic studies (1), rotary-shadowed electron micrographs of troponin (2), and intermediate resolution studies of both troponin-tropomyosin (3) and TnT-tropomyosin co-crystals (4) indicate that the tail domain is highly asymmetric and ϳ160 Å in length. Electron microscopy of tropomyosin-TnT co-crystals suggests that a long region of the tropomyosin C terminus may interact with the troponin tail (4). However, most of this extended interaction may be very weak, because a variety of other evidence suggests that only the C terminus of tropomyosin binds strongly to troponin (reviewed in Ref. 5). Recently, an x-ray crystallographic study of the tropomyosin C terminus identified and determined the structure of an 18-residue tropomyosin region that comprises a critical TnT-binding site (6). The TnT element that binds to this tropomyosin region is unknown.A new approach to these important interactions has been provided by the discovery that any of several mutations in the troponin tail region can cause the autosomal dominant disorder, familial hypertrophic cardiomyopathy (FHC). Regardless whether because of mutations in thick filament or thin filame...

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Molecular cloning and developmental expression of human cardiac troponin T

Cited by 56 publications

References 25 publications

A catalogue of genes in the cardiovascular system as identified by expressed sequence tags.

A catalogue of genes in the cardiovascular system as identified by expressed sequence tags.

Altered cardiac troponin T in vitro function in the presence of a mutation implicated in familial hypertrophic cardiomyopathy.

Folding and Function of the Troponin Tail Domain

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