[The effect of thyroid hormones and 5-azacytidine on the gene transcription of malic enzyme and 6-phosphogluconate dehydrogenase].

The effect of thyroid hormones and the methylation inhibitor 5-azacytidine on the level of expression of thyroid hormone-responsive genes (malic enzyme and 6-phosphogluconate dehydrogenase genes) has been studied. DNA-RNA hybridization has shown there is an inverse correlation between the level of DNA methylation and gene expression of malic enzyme and 6-phosphogluconate dehydrogenase. Thus it suggests that the regulation of thyroid hormone gene expression can take place via DNA methylation blocking and that DNA demethylation is part of structural changes essential to the binding of thyroid hormones with DNA elements recognized by thyroid hormone receptors and to further induction of synthesis of specific mRNA.

[Human thyroid gland DNA methylase in nodular and diffuse goiter].

The heterogeneity and some properties of DNA-methylases isolated from nonmalignant human thyroid formations--nodular and diffuse goiters--have been studied. Isoelectrofocusing of methylase preparations produced 6-7 distinct activity peaks distinguished by pI, activity towards Ca2+ and Mg2+, sensitivity towards dithiothreitol and capacity to methylase cytosine into mono-, di- and tripyrimidine blocks in vitro. The degree of DNA methylation in vivo depended on the origin of of the goiter.

[The regulation of the nuclear RNA polymerase activity of the liver and brain in rats of different ages by a cytoplasmic modulator of thyroxine action].

The effect of physiological, concentration of thyroxine and cytoplasm thyroxine-binding protein (thyroxine action modulator, TAM4) on the RNA-polymerase activity in rat liver and bain cells in ontogenesis was studied. The physiological doses of the hormone were shown not to effect the RNA-polymerase of isolated liver and brain nuclei, while TAM4 caused the stimulation of enzymatic activity in these organs. ++TAM4 stimulating effect in liver correlated with increasing animal age, while the maximum RNA-polymerase activation by tAM was discovered in young rats under one month-At later stage the RNA-polymerase activity was same as in the controls.

[Liver nuclear phospholipids of rats with varying thyroid status].

Thin-layer chromatography was used for fractionation of rat liver nuclear phospholipids after in vivo administration of 14C-sodium acetate. The administration of T3 to thyroidectomized rats caused a sharp increase in the incorporation of the label in all phospholipids of the nuclear fraction. The action of sphingomyelin and sphingomyelase on RNA-polymerase of nuclei isolated from the liver of thyroidectomized rats was tested.

[Multiple forms of DNA methylases in hepatic cell nuclei of animals in the normal state and in pathology].

Using hydrophobic chromatography multiple nature of DNA-methylating enzymes have been revealed. It was established that the most active enzymatic fraction of rats' liver and that of chicken are completely identical.

[The effect of thyroid hormones on DNA methylation in rat liver in vivo and in vitro].

Methylation of rat liver DNA was studied in vivo and in vitro in presence of various content of thyroid hormones. Both administration of triiodothyronine into intact rats and thyroidectomy led to considerable alterations in activity of endogenous DNA-methylases and in content of m5C in DNA although distinct correlation between these two factors was not detected. Alterations in the acceptor activity of endogenous DNA towards bacterial DNA-methylases of thy Mbu type demonstrated the processes occurring in vivo.

[Changes in the chromatin structure of the thyroid cells related to the expression of the thyroglobulin gene].

A highly purified thyroglobulin mRNA was isolated from human nodal euthyroid goiter. A full-length cDNA was synthesized from 33S RNA by using reverse transcriptase in the presence of human placenta ribonuclease inhibitor. A DNA complementary to human Tg mRNA was used in liquid hybridization experiments to quantify Tg mRNA.

[Thyroglobulin gene expression in human thyroid cells in various types of thyroid pathology].

Highly purified thyroglobulin mRNA was isolated from human nodal euthyroid goiter. Full length cDNA was synthesized from 33S RNA by using reverse transcriptase in the presence of human placenta ribonuclease inhibitor. DNA complementary to human Tg mRNA was used in liquid hybridization experiments to determine the quantity of Tg mRNA.

[Use of bacterial DNA-methylases for structuro-functional analysis of the eukaryotic genome].

Bacterial DNA-methylases with known recognition sites (RS) were used as probes for structural-and-functional analysis of eukaryotic genome. Adenine and cytosine DNA-methylases recognizing 4 to 6-member unique and degenerative nucleotide sequences having a symmetrical and asymmetrical structure were used for probing. The use of a set of methylases enabled the selection of a probe that was the most sensitive for the given pathology.

[Mapping of the thyroglobulin gene in high molecular weight DNA from the human thyroid in normal conditions and in thyroid pathology].

A highly purified thyroglobulin (Tg) mRNA was isolated from human nodal euthyroid goiter. Ultracentrifugation in a 5-20% sucrose density gradient revealed that the protein has a sedimentation coefficient of 33S. cDNA was synthesized from the 33S RNA, using reverse transcriptase in the presence of a human placental ribonuclease inhibitor.

[Stimulation with triiodothyronine of the synthesis of DNA, total proteins, nuclear proteins and nuclear matrix proteins in cultured cells of hepatoma Morris 7777].

Intensity of DNA and protein biosynthesis was decreased in Morris hepatoma 7777 cultivated cells in absence of thyroid hormones. Physiological concentrations of triiodothyronine increased synthesis of DNA and total proteins after lag phase within 12-48 hrs, while synthesis of nuclear and nuclear matrix proteins was stimulated already within 2 hrs. This suggests that stimulation of nuclear proteins biosynthesis occurred prior to the hormone effect on proliferation and cell metabolism.

[The effect of thyroid hormones on structural-functional relations in rat liver chromatin].

The effects of thyroid hormones on chromatin structure at different levels of its functional activity were investigated. No differences in the sensitivity of hepatocyte nuclei to DNAase I were found, presumably due to the restriction of acceptor sites for thyroid hormones on DNA.

[Binding of triiodothyronine to the nuclear matrix of the rat liver. The effect of thyroid hormones on the phosphorylation of nuclear matrix proteins].

The interaction of thyroid hormones with rat liver nuclear matrix proteins was studied. It was shown that the nuclear matrix contains the sites which bind triiodothyronine with a high affinity (Ka = 1.07 X 10(9) M-1) and limited capacity (maximal binding capacity--28.

[Determination of the ratio of membrane-bound and free polyribosomes and of the content of thyroglobulin in these fractions in normal thyroid gland cells and in several types of thyroid diseases].

The ratio of membrane-bound and free polyribosomes in thyroid gland cells was decreased two-fold in nodular euthyroid goiter and five-fold--in Hashimoto thyroiditis; a slight increase in thyroglobulin synthesis in free polyribosomes was noted in goiter. Impairments in transfer of the translation products across membranes of rough endoplasmic reticulum may be one of the causes of deteriorations in thyroglobulin synthesis in goiters.

[Thyroglobulin biosynthesis and the content of thyroglobulin polyribosomes of the thyroid gland cells in the normal state and in various types of thyroid pathology].

The content of polyribosomes in human thyroid cells was studied in health and different forms of thyroid pathology. In thyroid pathology, thyroglobulin (TG) polyribosome content in thyroid cells diminished in the following order: diffuse toxic goiter greater than mixed euthyroid goiter greater than nodular toxic goiter greater than Hashimoto's goiter and complete absence of TG synthesizing polyribosomes in thyroid cancer and congenital goiter cells. No correlation was revealed between polyribosome TG content and thyroid function.

[Protein biosynthesis and thyroglobulin polyribosome content of thyroid cells in congenital goiter].

The basic protein, synthetized in a cell-free (S 30) protein-synthetizing system from the thyroid cells in congenital goitre, is thyroalbumin, while 19S thyroglobulin synthesis is sharply reduced. Determination of the population extent of thyroglobulin polyribosomes has shown that they are practically absent in congenital goitre. It is suggested that thyroglobulin deficit in congenital goitre is provoked by deficiency in functioning thyroglobulin mRNA.

[Regulation of incorporation of amino acids into the thyroid gland proteins by thyroid hormones].

The effect of thyroid hormones and of iodide (1 x 10(-7)M, 5 x 10(-5)M) on the protein synthesis in the cell-free system made of the nodular goiter cells was investigated. As revealed, with the action of thyroid hormones the 14C-amino acids incorporation into the trichloracetic acid-precipitated proteins was considerably diminished. The greatest inhibition of the 14C-amino acids incorporation was observed in toxic (5 x 10(-5)M) hormone concentration.

[Content of thyroglobulin polyribosomes in normal and pathological thyroid cells].

The content of individual thyreoglobulin (TG) polyribosomes in human thyroid gland was studied in healthy persons and in patients with thyroid pathology. The content of TG polyribosomes makes up to 16.2% in normal thyroid tissue and is found to decrease down to 7.

[Protein biosynthesis in a cell-free protein synthesis system from nodular euthyroid goiter cells].

Analysis of proteins, synthesized in cell-free system using nodal euthyroid goiter, was carried out by polyacrylamide gel disc electrophoresis. Four protein farctions, incorporating labelled amino acids, were found: "complete" thyroglobulin, two its subunits and thyroalmbumin. This correlates with the concept that malignant cell synthesizes intensively proteins untypical for a normal tissue.