title: Hormonal regulation of DNA polymerase-beta activity in the rat thyroid gland.
abstract: Using hypophysectomized rats, it has been shown that DNA polymerase-beta activity in the adrenal gland and testis is largely influenced by pituitary trophic hormones. Sucrose gradient centrifugation of thyroid extracts revealed three peaks of DNA polymerase-beta activity sedimenting at 3.3S, 7.3S and 12S. Of these, hypophysectomy induced a decrease in the 3.3S DNA polymerase-beta, whereas other molecular forms were affected only slightly. DNA polymerase-alpha and -gamma activities were unaffected by hypophysectomy. These changes in DNA polymerase-beta caused by hypophysectomy were reversed by daily i.p. injection of TSH. Furthermore, stimulation of the thyroid by excess TSH induced by the administration of 1-methyl-2-mercaptoimidazole resulted in an increase of all forms of thyroid DNA polymerase-beta. These results show that the level of DNA polymerase is relatively constant after hypophysectomy but that DNA polymerase-beta in the rat thyroid gland is also modulated by TSH mainly through the change of activity of the polymerase-beta which sediments at 3.3S.
authors.affiliation: Department of Internal Medicine, Fujita-Gakuen Health University School of Medicine, Aichi, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Nagasaka
authors.forename: S
authors.initials: S
authors.lastname: Yoshida
authors.forename: A
authors.initials: A
authors.lastname: Nakai
authors.forename: T
authors.initials: T
authors.lastname: Ohyama
authors.forename: K
authors.initials: K
authors.lastname: Iwase
authors.forename: S
authors.initials: S
authors.lastname: Ohtani
authors.forename: H
authors.initials: H
authors.lastname: Nakagawa
authors.forename: R
authors.initials: R
authors.lastname: Masunaga
authors.forename: S
authors.initials: S
authors.lastname: Kato
authors.forename: T
authors.initials: T
authors.lastname: Kawabe
mesh_terms: D000818:Animals; D004256:DNA Polymerase I / Q000378:metabolism*; D004257:DNA Polymerase II / Q000378:metabolism; D004258:DNA Polymerase III / Q000378:metabolism; D007016:Hypophysectomy; D008297:Male; D008713:Methimazole / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013961:Thyroid Gland / Q000201:enzymology*; D013972:Thyrotropin / Q000494:pharmacology*
chemical_list: D008713:Methimazole; D013972:Thyrotropin; D004256:DNA Polymerase I; D004257:DNA Polymerase II; D004258:DNA Polymerase III