J. Biol. Chem., Vol. 259, Issue 4, 2035-2038, Feb, 1984
Effect of diabetes and hypothyroidism on the predominance of cardiac myosin heavy chains synthesized in vivo or in a cell-free system
WH Dillmann, A Barrieux and GS Reese
Rat cardiac ventricular myosins and RNA were prepared from normal,
diabetic, insulin-treated diabetic, hypothyroid, and 3,3',5-triiodo-L-
thyronine-treated hypothyroid rats. Myosin heavy chains isolated from
purified myosin or synthesized in vitro from cardiac RNAs were subjected to
partial protease digestion during sodium dodecyl sulfate- polyacrylamide
gel electrophoresis. It was found that peptide maps obtained from cardiac
myosin heavy chains of hypothyroid and diabetic rats were identical but
differed from the maps of myosin heavy chain from control and
hormone-treated animals. The same results were obtained, whether the heavy
chains were isolated from purified myosin synthesized in the intact heart
or from translation products coded for by cardiac RNAs added to the
modified reticulocyte lysate. These results indicate that the myosin heavy
chain RNA species present in the hypothyroid heart is also expressed during
insulin deficiency but differs from the species expressed in normal
animals. The expression of the two myosin heavy chain RNA species found in
the rat cardiac ventricle appears to be independently regulated by these
two hormones.
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