Key result
Thyroid hormones increase cardiac V1 myosin expression whereas androgens reduce it in masticatory muscles.
Modulation of V1 gene transcription in striated muscle depends on both the target muscle and the specific hormone.
No immediate clinical implications from this animal study; leaves open muscle-specific hormonal regulation of myosin isoforms.
The finding that V1 cardiac myosin is expressed in masticatory skeletal muscles of the rabbit provided a unique opportunity for comparing the hormonal regulation of V1 in skeletal and cardiac muscles. Thyroid hormones had no significant effect on the postnatal expression of V1 in masticatory muscles, but increased this expression in cardiac ventricles. In contrast, androgenic hormones reduced V1 expression in masticatory muscles, but did not affect it significantly in cardiac ventricles. Modulation of V1 gene transcription in striated muscle is thus shown here to depend both on the target muscle and on the hormone.
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d’Albis et al. (1993) studied this question. Androgenic and thyroid hormones was evaluated on V1 myosin expression in masticatory skeletal muscles and cardiac ventricles. Thyroid hormones increased V1 myosin expression in cardiac ventricles but not masticatory muscles, whereas androgenic hormones reduced V1 expression in masticatory muscles but not cardiac ventricles.
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