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Alpha actin isoforms expression in human and rat adult cardiac conduction system

Orlandi, Augusto
Ferlosio, Amedeo
Hirota, Seiichi
Spagnoli, L. G.
Published in Differentiation. 2009, vol. 77, no. 4, p. 360-368
Abstract In the adult heart, cardiac muscle comprises the working myocardium and the conduction system (CS). The latter includes the sinoatrial node (SAN), the internodal tract or bundle (IB), the atrioventricular node (AVN), the atrioventricular bundle (AVB), the bundle branches (BB) and the peripheral Purkinje fibers (PF). Most of the information concerning the phenotypic features of CS tissue derives from the characterization of avian and rodent developing hearts; data concerning the expression of actin isoforms in adult CS cardiomyocytes are scarce. Using specific antibodies, we investigated the distribution of alpha-skeletal (alpha-SKA), alpha-cardiac (alpha-CA), alpha-smooth muscle (alpha-SMA) actin isoforms and other muscle-typical proteins in the CS of human and rat hearts at different ages. SAN and IB cardiomyocytes were characterized by the presence of alpha-SMA, alpha-CA, calponin and caldesmon, whereas alpha-SKA and vimentin were absent. Double immunofluorescence demonstrated the co-localisation of alpha-SMA and alpha-CA in I-bands of SAN cardiomyocytes. AVN, AVB, BB and PF cardiomyocytes were alpha-SMA, calponin, caldesmon and vimentin negative, and alpha-CA and alpha-SKA positive. No substantial differences in actin isoform distribution were observed in human and rat hearts, except for the presence of isolated subendocardial alpha-SMA positive cardiomyocytes co-expressing alpha-CA in the ventricular septum of the rat. Aging did not influence CS cardiomyocyte actin isoform expression profile. These findings support the concept that cardiomyocytes of SAN retain the phenotype of a developing myogenic cell throughout the entire life span.
Keywords Actins/chemistry/ metabolismAdolescentAdultAge FactorsAgedAged, 80 and overAnimalsCells, CulturedFemaleGene Expression RegulationHeart Conduction System/ metabolismHumansImmunohistochemistryMaleMiddle AgedMyocytes, Cardiac/metabolismProtein Isoforms/metabolismRatsSinoatrial Node/metabolismYoung Adult
PMID: 19281784
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Research group Groupe Christine Chaponnier (pathologie et immunologie) (171)
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ORLANDI, Augusto et al. Alpha actin isoforms expression in human and rat adult cardiac conduction system. In: Differentiation, 2009, vol. 77, n° 4, p. 360-368. https://archive-ouverte.unige.ch/unige:11500

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Deposited on : 2010-08-27

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