Human Cardiac Troponin T: Identification of Fetal Isoforms and Assignment of the TNNT2 Locus to Chromosome 1q

Townsend, P. J.; Farza, Hend; MacGeoch, C.; Spurr, Nigel K.; Wade, Robert; Gahlmann, Reinhold; Yacoub, Magdi H.; Barton, Paul J.R.

doi:10.1006/geno.1994.1271

Cited by 64 publications

(41 citation statements)

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“…It coded for a 288-amino acid cTnT protein with an expected molecular size of 35 kD. The sequence of the cTnT protein was completely identical to that of adult cTnT protein published by Townsend et al (29). The successful induction of a G → A nucleotide substitution (Arg 92 Gln mutation) in the cTnT cDNA was confirmed by sequencing.…”

Section: Resultssupporting

confidence: 54%

“…A 10-g aliquot of total RNA was loaded onto a formaldehyde-agarose gel, subjected to electrophoresis, and transferred to a nylon membrane (Zeta Probes; Bio-Rad Laboratories, Cambridge, MA). Sequences of human and mouse cTnT mRNAs were compared (29,30), and transgene-specific, mouse-specific, and pan-specific cTnT probes were designed. The transgene-specific and pan-specific probes were 160-and 950-bp-long and were excised from the 3 Ј and 5 Ј region of human cTnT cDNA, respectively.…”

Section: Methodsmentioning

confidence: 99%

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Dominant-negative effect of a mutant cardiac troponin T on cardiac structure and function in transgenic mice.

et al. 1998

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Hypertrophic cardiomyopathy (HCM) is a disease of sarcomeric proteins. The mechanism by which mutant sarcomeric proteins cause HCM is unknown. The leading hypothesis proposes that mutant sarcomeric proteins exert a dominant-negative effect on myocyte structure and function. To test this, we produced transgenic mice expressing low levels of normal or mutant human cardiac troponin T (cTnT).We constructed normal (cTnT-Arg 92) and mutant (cTnTGln 92 ) transgenes, driven by a murine cTnT promoter, and produced three normal and five mutant transgenic lines, which were identified by PCR and Southern blotting. Expression levels of the transgene proteins, detected using a specific antibody, ranged from 1 to 10% of the total cTnT pool. M-mode and Doppler echocardiography showed normal left ventricular dimensions and systolic function, but diastolic dysfunction in the mutant mice evidenced by a 50% reduction in the E/A ratio of mitral inflow velocities. Histological examination showed cardiac myocyte disarray in the mutant mice, which amounted to 1-15% of the total myocardium, and a twofold increase in the myocardial interstitial collagen content.Thus, the mutant cTnT-Gln 92 , responsible for human HCM, exerted a dominant-negative effect on cardiac structure and function leading to disarray, increased collagen synthesis, and diastolic dysfunction in transgenic mice. ( J.

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Section: Resultssupporting

confidence: 54%

Section: Methodsmentioning

confidence: 99%

Dominant-negative effect of a mutant cardiac troponin T on cardiac structure and function in transgenic mice.

et al. 1998

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“…The cDNA for wild type human cardiac troponin T (adult isoform) was cloned by reverse transcription-PCR using primers based on the published cDNA sequence (35) and standard methods (36): HCTnT, 5Ј-GACCATGGCTGACATAGAAGAGGT; HCTnT, 3Ј-GAGGATCCTAT-TTCCAGCGCCCGGTGACTT. The I79N mutant was made using overlapping sequential PCR (36).…”

Section: Clone Constructionmentioning

confidence: 99%

Abnormal Contractile Function in Transgenic Mice Expressing a Familial Hypertrophic Cardiomyopathy-linked Troponin T (I79N) Mutation

Miller

Szczêsna

Housmans

et al. 2001

Journal of Biological Chemistry

113

106

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This study characterizes a transgenic animal model for the troponin T (TnT) mutation (I79N) associated with familial hypertrophic cardiomyopathy. To study the functional consequences of this mutation, we examined a wild type and two I79N-transgenic mouse lines of human cardiac TnT driven by a murine ␣-myosin heavy chain promoter. Extensive characterization of the transgenic I79N lines compared with wild type and/or nontransgenic mice demonstrated: 1) normal survival and no cardiac hypertrophy even with chronic exercise; 2) large increases in Ca 2؉ sensitivity of ATPase activity and force in skinned fibers; 3) a substantial increase in the rate of force activation and an increase in the rate of force relaxation; 4) lower maximal force/cross-sectional area and ATPase activity; 5) loss of sensitivity to pHinduced shifts in the Ca 2؉ dependence of force; and 6) computer simulations that reproduced experimental observations and suggested that the I79N mutation decreases the apparent off rate of Ca 2؉ from troponin C and increases cross-bridge detachment rate g. Simulations for intact living fibers predict a higher basal contractility, a faster rate of force development, slower relaxation, and increased resting tension in transgenic I79N myocardium compared with transgenic wild type. These mechanisms may contribute to mortality in humans, especially in stimulated contractile states.

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“…TNNT2 was mapped by somatic cell hybrid analysis and by fluorescent in situ hybridization to chromosome 1q32. 71,73 The structural organization and the complete nucleotide sequence have been determined in the rat by Jin et al, 74 and the first mutations reported in FHC were numbered according to this rat structure. 75 We have partially established the organization of the human gene, and this allows us now to precisely identify the position of the mutations within exons, including those alternatively spliced during development, and also to use an amino acid numbering that reflects the full coding potential of human TNNT2.…”

Section: Tnnt2mentioning

confidence: 99%

Familial Hypertrophic Cardiomyopathy

Bonne

Carrier

Richard

et al. 1998

Circulation Research

314

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Abstract-Hypertrophic cardiomyopathy is characterized by left and/or right ventricular hypertrophy, which is usually asymmetric and involves the interventricular septum. Typical morphological changes include myocyte hypertrophy and disarray surrounding the areas of increased loose connective tissue. Arrhythmias and premature sudden deaths are common. Hypertrophic cardiomyopathy is familial in the majority of cases and is transmitted as an autosomal-dominant trait. The results of molecular genetics studies have shown that familial hypertrophic cardiomyopathy is a disease of the sarcomere involving mutations in 7 different genes encoding proteins of the myofibrillar apparatus: ␤-myosin heavy chain, ventricular myosin essential light chain, ventricular myosin regulatory light chain, cardiac troponin T, cardiac troponin I, ␣-tropomyosin, and cardiac myosin binding protein C. In addition to this locus heterogeneity, there is a wide allelic heterogeneity, since numerous mutations have been found in all these genes. The recent development of animal models and of in vitro analyses have allowed a better understanding of the pathophysiological mechanisms associated with familial hypertrophic cardiomyopathy. One can thus tentatively draw the following cascade of events: The mutation leads to a poison polypeptide that would be incorporated into the sarcomere. This would alter the sarcomeric function that would result (1) in an altered cardiac function and then (2) in the alteration of the sarcomeric and myocyte structure. Some mutations induce functional impairment and support the pathogenesis hypothesis of a "hypocontractile" state followed by compensatory hypertrophy. Other mutations induce cardiac hyperfunction and determine a "hypercontractile" state that would directly induce cardiac hypertrophy. The development of other animal models and of other mechanistic studies linking the genetic mutation to functional defects are now key issues in understanding how alterations in the basic contractile unit of the cardiomyocyte alter the phenotype and the function of the heart. (Circ Res. 1998;83:580-593.)

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Human Cardiac Troponin T: Identification of Fetal Isoforms and Assignment of the TNNT2 Locus to Chromosome 1q

Cited by 64 publications

References 0 publications

Dominant-negative effect of a mutant cardiac troponin T on cardiac structure and function in transgenic mice.

Dominant-negative effect of a mutant cardiac troponin T on cardiac structure and function in transgenic mice.

Abnormal Contractile Function in Transgenic Mice Expressing a Familial Hypertrophic Cardiomyopathy-linked Troponin T (I79N) Mutation

Familial Hypertrophic Cardiomyopathy

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