Sarkar Pradip K, Morris Jason J, Martin Joseph V
Department of Basic Sciences, Parker College of Chiropractic, 2500 Walnut Hill Lane, Dallas, Texas 75229, USA.
Indian J Exp Biol. 2011 Mar;49(3):169-76.
The present study was undertaken to examine calmodulin-dependent effect of thyroid hormones (THs) on synaptosomal protein phosphorylation in mature rat brain. Effect of L-triiodothyronine (L-T3) on in vitro protein phosphorylation was measured in a hypotonic lysate of synaptosomes prepared from adult male rat cerebral cortex, incubated in presence and absence of calcium ion (Ca2+) and calmodulin. L-T3 significantly enhanced incorporation of 32P into synaptosomal proteins as compared to basal level of phosphorylation in the presence of Ca2+ and calmodulin. Under these conditions, increase in protein phosphorylation was 47, 74 and 52% for 10 nM, 100 nM and 1 microM L-T3, respectively. Chelation of Ca2+ using ethylene glycol-bis (2-aminoethylether)-N, N, N', N'-tetraacetic acid (EGTA) inhibited the effects of Ca2+/calmodulin on TH-stimulated protein phosphorylation levels. This study suggests that a high proportion of L-T3-stimulated protein phosphorylation involves Ca2+/calmodulin-dependent pathways in adult rat cerebrocortical synaptosomes.
本研究旨在探讨甲状腺激素（THs）对成年大鼠大脑突触体蛋白磷酸化的钙调蛋白依赖性作用。在存在和不存在钙离子（Ca2+）及钙调蛋白的情况下，测定L-三碘甲状腺原氨酸（L-T3）对成年雄性大鼠大脑皮质制备的突触体低渗裂解物中体外蛋白磷酸化的影响。与存在Ca2+和钙调蛋白时的基础磷酸化水平相比，L-T3显著增强了32P掺入突触体蛋白的量。在这些条件下，10 nM、100 nM和1 μM L-T3的蛋白磷酸化增加分别为47%、74%和52%。使用乙二醇双（2-氨基乙醚）-N，N，N'，N'-四乙酸（EGTA）螯合Ca2+可抑制Ca2+/钙调蛋白对TH刺激的蛋白磷酸化水平的影响。本研究表明，在成年大鼠脑皮质突触体中，很大一部分L-T3刺激的蛋白磷酸化涉及Ca2+/钙调蛋白依赖性途径。
