Effect of hypothyroidism on the subcellular distribution of Ca2+/calmodulin-stimulated protein kinase II in chicken brain during posthatch development.
In developing chicken brain Ca2+/calmodulin-stimulated protein kinase II (CaMPK-II) changes from being primarily cytosolic to being primarily particulate during the protracted maturation period. To investigate whether thyroid hormone levels may be involved in regulating this subcellular redistribution, we raised chickens from 1 day posthatching on food soaked in 0.15% (wt/vol) propylthiouracil (PTU) plus 0.05% (wt/vol) methimazole (MMI). This produced a mild hypothyroidism specifically during the maturation period and resulted in a 67% reduction in the levels of free triiodothyronine (T3) at 42 days. The concentrations of alpha- and beta-CaMPK-II in cytosol (S3) and crude synaptic membrane (P2M) fractions from forebrain were measured by three methods: Ca2+/calmodulin- or ZN2+-stimulated autophosphorylation or binding of biotinylated calmodulin. By all three methods hypothyroid animals showed a marked retardation of the redistribution of both subunits of CaMPK-II: an increase in the concentration of the enzyme in S3 and a corresponding decrease in P2M with no overall change in the total amount of enzyme and little apparent change in the concentration of other proteins. In both fractions, there was a parallel change in the Ca2+/calmodulin-stimulated phosphorylation of endogenous protein substrates but no change in the basal or cyclic AMP-stimulated protein phosphorylation. Supplementing the PTU/MMI-treated diet with thyroxine (0.5 ppm) prevented all of the observed changes.
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Neuroscience Group, Faculty of Medicine and Health Sciences, University of Newcastle, Callaghan, New South Wales, Australia.
Rostas
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D000367:Age Factors; D000818:Animals; D001345:Autoradiography; D015153:Blotting, Western; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology; D002645:Chickens / Q000254:growth & development*; D003600:Cytosol / Q000201:enzymology; D007037:Hypothyroidism / Q000139:chemically induced / Q000201:enzymology*; D008713:Methimazole / Q000494:pharmacology; D010766:Phosphorylation; D011441:Propylthiouracil / Q000494:pharmacology; D016548:Prosencephalon / Q000201:enzymology* / Q000254:growth & development / Q000503:physiopathology; D011506:Proteins / Q000378:metabolism; D013569:Synapses / Q000201:enzymology; D014284:Triiodothyronine / Q000097:blood; D015032:Zinc / Q000494:pharmacology
D011506:Proteins; D014284:Triiodothyronine; D008713:Methimazole; D011441:Propylthiouracil; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D015032:Zinc