Molecular Cloning, Sequencing and Expression of an Isoform of Cardiac Alpha Tropomyosin from the Mexican Axolotl (Ambystoma mexicanum)

Luque, Eileen A.; Lemanski, Larry F.; Dube, Dipak K.

doi:10.1006/bbrc.1994.2184

Cited by 17 publications

(13 citation statements)

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“…Three isoforms of axolotl tropomyosin have been isolated, sequenced, and designated ATmC-1, ATmC-2, and ATmC-3 [Luque et al, 1994;Luque et al, 1997]. We believe that two (ATmC-1 and ATmC-2) are encoded by the putative alpha-TM gene and the third (ATmC-3) is encoded by a TM-4 type gene.…”

Section: Discussionmentioning

confidence: 97%

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Characterization of a TM‐4 type tropomyosin that is essential for myofibrillogenesis and contractile activity in embryonic hearts of the Mexican axolotl*

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Zajdel

McLean

et al. 2002

J of Cellular Biochemistry

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A striated muscle isoform of a Tropomyosin (TM-4) gene was characterized and found to be necessary for contractile function in embryonic heart. The full-length clone of this isoform was isolated from the Mexican axolotl (Ambystoma mexicanum) and named Axolotl Tropomyosin Cardiac-3 (ATmC-3). The gene encoded a cardiac-specific tropomyosin protein with 284 amino acid residues that demonstrated high homology to the Xenopus cardiac TM-4 type tropomyosin. Northern blot analysis indicates a transcript of approximately 1.25 kb in size. RT-PCR and in situ hybridization demonstrated that this isoform is predominantly in cardiac tissue. Our laboratory uses an animal model that carries a cardiac lethal mutation (gene c), this mutation results in a greatly diminished level of tropomyosin protein in the ventricle. Transfection of ATmC-3 DNA into mutant hearts increased tropomyosin levels and promoted myofibrillogenesis. ATmC-3 expression was blocked in normal hearts by transfection of exon-specific anti-sense oligonucleotide (AS-ODN). RT-PCR confirmed lower transcript expression of ATmC-3 and in vitro analysis confirmed the specificity of the ATmC-3 exon 2 anti-sense oligonucleotide. These AS-ODN treated hearts also had a disruption of myofibril organization and disruption of synchronous contractions. These results demonstrated that a striated muscle isoform of the TM-4 gene was expressed embryonically and was necessary for normal structure and function of the ventricle.

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Section: Discussionmentioning

confidence: 97%

“…Three isoforms of tropomyosin have been identified in the axolotl, two putatively encoded by the alpha-gene, Axolotl Tropomyosin Cardiac-1 (ATmC-1 and ATmC-2) [Luque et al, 1994[Luque et al, , 1997. The third, characterized here as ATmC-3, is most likely a TM-4 type encoded by a separate gene.…”

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confidence: 98%

Characterization of a TM‐4 type tropomyosin that is essential for myofibrillogenesis and contractile activity in embryonic hearts of the Mexican axolotl*

Spinner

Zajdel

McLean

et al. 2002

J of Cellular Biochemistry

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“…in the regulation of contraction and its own expression regulation by other tissue specific factors using the gene c mutation animal system [Lemanski, 1976a,b;Lemanski et al, 1985Lemanski et al, , 1996LaFrance et al, 1993;Luque et al, 1994Luque et al, , 1997Gaur et al, 2001]. The troponin complex along with tropomyosin are essential for the efficient use of calcium in muscle contraction.…”

Section: Discussionmentioning

confidence: 99%

Molecular and immunohistochemical analyses of cardiac troponin T during cardiac development in the Mexican axolotl, Ambystoma mexicanum

Zhang

Pietras

Sferrazza

et al. 2006

J of Cellular Biochemistry

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The Mexican axolotl, Ambystoma mexicanum, is an excellent animal model for studying heart development because it carries a naturally occurring recessive genetic mutation, designated gene c, for cardiac nonfunction. The double recessive mutants (c/c) fail to form organized myofibrils in the cardiac myoblasts resulting in hearts that fail to beat. Tropomyosin expression patterns have been studied in detail and show dramatically decreased expression in the hearts of homozygous mutant embryos. Because of the direct interaction between tropomyosin and troponin T (TnT), and the crucial functions of TnT in the regulation of striated muscle contraction, we have expanded our studies on this animal model to characterize the expression of the TnT gene in cardiac muscle throughout normal axolotl development as well as in mutant axolotls. In addition, we have succeeded in cloning the full-length cardiac troponin T (cTnT) cDNA from axolotl hearts. Confocal microscopy has shown a substantial, but reduced, expression of TnT protein in the mutant hearts when compared to normal during embryonic development.

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“…Homozygous mutant (c/c) embryos are first distinguishable from their normal siblings (+/+ or +/c) at stage 34, when the mutant embryos develop hearts that fail to beat and eventually die from lack of circulation. Subsequent studies have demonstrated the defects in myofibrillogenesis and significantly decreased tropomyosin expression in the mutant embryonic hearts [12][13][14][15][16][17]. As a tropomyosin-interacting protein, cardiac troponin T has also been studied in this system in our laboratory.…”

Section: Introductionmentioning

confidence: 99%

Role of myofibril-inducing RNA in cardiac TnT expression in developing Mexican axolotl

Sferrazza

Zhang

Jia

et al. 2007

Biochemical and Biophysical Research Communications

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Molecular Cloning, Sequencing and Expression of an Isoform of Cardiac Alpha Tropomyosin from the Mexican Axolotl (Ambystoma mexicanum)

Cited by 17 publications

References 0 publications

Characterization of a TM‐4 type tropomyosin that is essential for myofibrillogenesis and contractile activity in embryonic hearts of the Mexican axolotl*

Characterization of a TM‐4 type tropomyosin that is essential for myofibrillogenesis and contractile activity in embryonic hearts of the Mexican axolotl*

Molecular and immunohistochemical analyses of cardiac troponin T during cardiac development in the Mexican axolotl, Ambystoma mexicanum

Role of myofibril-inducing RNA in cardiac TnT expression in developing Mexican axolotl

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