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Thyroid Hormone Binding and Regulation of Adrenergic Enzymes in Two Neuroblastoma Cell Lines
Author(s) -
Safaei Roohangiz,
Timiras Paola S.
Publication year - 1985
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1985.tb07206.x
Subject(s) - endocrinology , medicine , thyroid , hormone , enzyme , neuroblastoma , adrenergic , thyroid hormones , biology , chemistry , cell culture , receptor , biochemistry , genetics
Two neuroblastoma cell lines were cultured in control (euthyroid) and hypothyroid media and examined for protein, RNA and DNA content, activity of the catecholaminergic enzymes tyrosine hydroxylase (TH, EC 1.14. 16.2) and monoamine oxidase‐A (MAO‐A, EC 1.4.3.4), and for L‐triiodothyronine (T 3 ) nuclear receptors. In the hypothyroid condition, the rate of cell division and the levels of RNA and protein as well as the activities of TH and MAO were lower than in the euthyroid condition, the reduction being more marked in the Ē than in the A 2 (1) cell line. T 3 nuclear receptors, unaltered in affinity, were increased in number in the hypothyroid medium, possibly as a regulatory response to hormonal deficiency. Examination of a possible relationship between T 3 occupancy and TH activity in the Ē cells, most sensitive to thyroid hormone deficiency, revealed that induction of TH activity by T 3 is dose‐dependent and correlates with the number of nuclear sites occupied by the hormone. When neuroblastoma cells were induced to differentiate by the addition of sodium butyrate to the medium, parameters of cell growth (protein, RNA) and enzyme activity (TH and MAO‐A) increased in both cell lines irrespective of the presence of thyroid hormones. These data indicate that thyroid hormones, through their nuclear receptors, directly affect the activity of catecholaminergic enzymes in cultured, immature (undifferentiated) neurons.