Heterogeneity of alpha-cardiac myosin heavy chains in a small marsupial, Antechinus flavipes, and the effect of hypothyroidism on its ventricular myosins

Hoh, Joseph F. Y. and Withers, Kerry W. and Zhong, Wendy W. H. (2008) Heterogeneity of alpha-cardiac myosin heavy chains in a small marsupial, Antechinus flavipes, and the effect of hypothyroidism on its ventricular myosins. Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology, 178 (3). pp. 279-284. ISSN 0174-1578


The effect of drug-induced hypothyroidism on ventricular myosin gene expression was explored in a small marsupial, Antechinus flavipes. Pyrophosphate gel electrophoresis, SDS-PAGE and western blotting were used to analyse changes in native myosin isoforms and myosin heavy chains (MyHCs) in response to hypothyroidism. In some animals, five instead of the normal three native myosin components were found: V1a, V1b, V1c, V2 and V3, in order of decreasing mobility. In western blots, V1a, V1b, and V1c reacted with anti-a-MyHC antibody, but not with anti-B-MyHC, whereas V2 and V3 reacted with anti-B-MyHC antibody. SDS-PAGE of the unusual ventricular myosins revealed three MyHC isoforms, two of which bound anti-a-MyHC antibody while the third bound anti-B-MyHC antibody.
We conclude that V1a, V1b, V1c are triplets arising from the dimerization of two distinct a-MyHC isoforms.
Hypothyroidism, veriWed by metabolic studies, decreased a-MyHC content significantly (t-test, P < 0.001) from 91.6 5.9% (SEM, n = 4) in control animals to 67.2 5.7% (SEM, n = 4) in hypothyroid animals, with a concomitant increase in B-MyHC content. We conclude that in adult marsupials, ventricular myosins are also responsive to changes in the thyroid state as found in eutherians, and suggest that evolution of the molecular mechanisms underlying this thyroid responsiveness predate the divergence of marsupials and eutherians.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Author version not held.
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 09 Apr 2010 08:42
Last Modified: 11 Feb 2015 05:04
Uncontrolled Keywords: marsupial; Antechinus; cardiac muscle; myosin heavy chain; thyroid hormone
Fields of Research : 06 Biological Sciences > 0606 Physiology > 060604 Comparative Physiology
11 Medical and Health Sciences > 1102 Cardiovascular Medicine and Haematology > 110201 Cardiology (incl. Cardiovascular Diseases)
11 Medical and Health Sciences > 1101 Medical Biochemistry and Metabolomics > 110106 Medical Biochemistry: Proteins and Peptides (incl. Medical Proteomics)
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970106 Expanding Knowledge in the Biological Sciences
Identification Number or DOI: 10.1007/s00360-007-0220-1
URI: http://eprints.usq.edu.au/id/eprint/7341

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