Signal transduction systems for thyroid cell proliferation and differentiation and their abnormalities in Graves' thyroid cells

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We studied the signal transduction systems for thyroid cell proliferation and differentiation. We also studied the abnormalities in the signal transduction systems in the Graves' thyroid cells.1. Signal transduction systems for thyroid cell proliferation: PO(phosphatidyl inositol) turnover, IP3 production, cytoplasmic free calcium ([Ca^<2+>]i), arachidonic acid release and PG (prostaglandins) production. EGF stiumulates porcine thyroid cell proliferation. However, the signals for the thyroid cell proliferation were not known. We found that EGF induces PI turnover, produces IP3, and increases [Ca^<2+>]i, EGF also releases arachidonic acid from phosphatidyl inositol and stimulates PG production. The results indicate that PI turnover, IP3 production, [Ca^<2+>]i increase, arachidonic acid release and PG production play important roles for thyroid cell proliferation.2. Signal transduction systems for thyroid cell differentiation: cAMP mediated processes. TSH differentiates porcine thyroid cells. TSH stimulate cAMP production, follicle formation and thyroid hormone synthesis. Cyclic AMP plays important roles for these processes. TSH stimulates thyroid cell differentiation through cAMP-mediated processes.3. Abnormalities in the Graves' thyroid cells. There are some abnormalities in the cAMP and PG production systems in the Graves thyroid cells. These abnormalities may play some role in the pathogenesis of Graves' disease.Using cultured thyroid cells, we revealed the signal transduction systems for thyroid cell proliferation and differentiation. We also revealed the abnormalities in the signal transduction systems in the Graves' thyroid cells.