Cardiomyocyte growth and sarcomerogenesis at the intercalated disc

Wilson, Amanda J; Schönauer, Roman; Ehler, Elisabeth; Agarkova, Irina; Bennett, Pauline M (2014). Cardiomyocyte growth and sarcomerogenesis at the intercalated disc. Cellular and molecular life sciences, 71(1), pp. 165-181. Springer 10.1007/s00018-013-1374-5

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Cardiomyocytes grow during heart maturation or disease-related cardiac remodeling. We present evidence that the intercalated disc (ID) is integral to both longitudinal and lateral growth: increases in width are accommodated by lateral extension of the plicate tread regions and increases in length by sarcomere insertion within the ID. At the margin between myofibril and the folded membrane of the ID lies a transitional junction through which the thin filaments from the last sarcomere run to the ID membrane and it has been suggested that this junction acts as a proto Z-disc for sarcomere addition. In support of this hypothesis, we have investigated the ultrastructure of the ID in mouse hearts from control and dilated cardiomyopathy (DCM) models, the MLP-null and a cardiac-specific β-catenin mutant, cΔex3, as well as in human left ventricle from normal and DCM samples. We find that the ID amplitude can vary tenfold from 0.2 μm up to a maximum of ~2 μm allowing gradual expansion during heart growth. At the greatest amplitude, equivalent to a sarcomere length, A-bands and thick filaments are found within the ID membrane loops together with a Z-disc, which develops at the transitional junction position. Here, also, the tops of the membrane folds, which are rich in αII spectrin, become enlarged and associated with junctional sarcoplasmic reticulum. Systematically larger ID amplitudes are found in DCM samples. Other morphological differences between mouse DCM and normal hearts suggest that sarcomere inclusion is compromised in the diseased hearts.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy
04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy > Cell Biology

UniBE Contributor:

Schönauer, Roman

Subjects:

600 Technology > 610 Medicine & health

ISSN:

1420-682X

Publisher:

Springer

Language:

English

Submitter:

Roman Schönauer

Date Deposited:

11 Aug 2014 11:32

Last Modified:

17 Dec 2014 06:41

Publisher DOI:

10.1007/s00018-013-1374-5

PubMed ID:

23708682

Uncontrolled Keywords:

Heart structure, Dilated cardiomyopathy, Adherens junction, Electron microscopy, Transitional junction

BORIS DOI:

10.7892/boris.47014

URI:

https://boris.unibe.ch/id/eprint/47014

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