Mechanisms of stimulation of protein synthesis by thyroid hormones in vivo.

Sokoloff, Louis; Roberts, Patricia; Januska, Margaret; Kline, J E

doi:10.1073/pnas.60.2.652

Cited by 69 publications

(11 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The concentrations of thyroid hormone needed to elicit in vitro responses are usually far in excess to those which are operative in vivo and it is a general feature of all in vitro systems to require concentrations of thyroid hormone 1000 to 10000 foId in excess to those required in vivo (Goldfine et al, 1975a). The use of high doses of thyroid hormone in vivo has been deplored but as well justified on the assumption that the mechanism of action utilizing physiologic and pharmacologic doses could be qualitatively similar (Sokoloff et al, 1968). In analysing experimental results it is particularly important to consider dose level since, as indicated above, some of the effects of thyroid hormone are biphasic, being stimulatory at low doses and inhibitory at high doses (Hoch, 1974;Vonderhaar, 1975).…”

Section: Theories O N the Mode O F Thyroid Hormone Actionmentioning

confidence: 99%

The Action of Thyroid Hormone

Bernal

Refetoff

1977

Clinical Endocrinology

104

View full text Add to dashboard Cite

SUMMARYThyroid hormone affects both developmental and metabolic processes. It has a relatively specific effect on the synthesis of a number of enzymes and other proteins. The fundamental cellular mechanism of action seems to be at the level of genetic regulation. It involves interaction with nuclear receptors, leading to an activation of the protein synthesizing machinery. How binding to receptors is coupled to genetic activation is completely unknown. At least part of the metabolic effects of thyroid hormone could be mediated through an interaction with mitochondria and cell membrane, and with some enzymatic systems such as adenylcyclase.

show abstract

Section: Theories O N the Mode O F Thyroid Hormone Actionmentioning

confidence: 99%

The Action of Thyroid Hormone

Bernal

Refetoff

1977

Clinical Endocrinology

104

View full text Add to dashboard Cite

show abstract

“…subjects. The synthesis of the LCAT in the liver seems to be independent of the thyroid activity, though a positive effect of thyroid honnones on protein synthesis in the liver is known (Tata 1964, Sokoloff et al 1968). …”

Section: Discussionmentioning

confidence: 98%

Plasma Lecithin: Cholesterol Acyltransferase Activity in Hypo- and Hyperthyroidism

Adlkofer¹,

Armbrecht²,

Schleusener³

et al. 1974

Horm Metab Res

View full text Add to dashboard Cite

The plasma lecithin:cholesterol acyltransferase (LCAT) activity was determined in 5 normal subjects and in 5 hypoand 1 hyperthyroid patients by measuring the decrease of lecithin and the esterification of cholesterol during a 18 hrs incubation period_ The absolute decrease in lecithin and the increase in esterified cholesterol were significantly higher in the hypothyroid group than in the other groups, whereas the percentage decrease in lecithin was similar in all three groups. In order to exdude the influence of changes in substrate an assay system was used which contained Iipoprotein-free plasma and a defined amount of substrate. Under these conditions the esterification did not show any difference in the eu-, hypo-and hyperthyroid subjects.The results suggest that the concentration of the LCAT in plasma is in the normal range in patients with thyroid disorders and that the turnover of lecithin and unesterified cholesterol depends on their concentration in plasma. The data were compared to those obtained from patients with a cirrhosis of the Iiver.

show abstract

“…By contrast, the effect we describe here is produced by physiological concentrations of T3 or T4 within an hour at most. The rapidity of the response suggests that stimulation of sulfation is not mediated solely by the high-affinity nuclear binding mechanism for T3 (27,28); and the low concentrations of hormones involved make it likely that none of the known in vtitro actions of T3 or T4 on cytoplasmic components (29)(30)(31)(32) or permeability and uptake mechanisms (33,34) is at work, either.…”

Section: Discussionmentioning

confidence: 99%

Enhancement of somatomedin titers of normal and hypopituitary sera by addition of L-triiodothyronone in vitro at physiological concentrations.

Audhya¹,

Gibson²

1975

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Somatomedin potencies of sera were assayed by following sulfation of mucopolysaccharides in chick embryo sterna in vitro. Apparent potencies of sera from hypophysectomized rats, maintained on a low-iodine diet, were restored to levels above normal by addition to the incubation medium of L-triiodothyronine at 10-7 mol/liter of serum. The potencies of normal rat, human, and fetal calf sera were raised 1.3-to 3-fold by addition of triiodothyronine at 10-9-10-7 mol/liter of serum. L-Thyroxine was about 10 times less effective than triiodothyronine. Triiodothyronine alone did not stimulate sulfation to nearly the same extent as triiodothyronine plus serum, even at higher concentrations. Serum could not be substituted in this system by any of six purified hormones, nor by trace metals or amino acids not included in the incubation mixture. It is concluded that triiodothyronine, in combination with a factor in serum, causes a rapid stimulation of sulfation in chick embryo cartilage, and that thyroid hormones may be involved in the action of normal serum on this tissue.Incorporation of sulfate into mucopolysaccharides of cartilage is stimulated by one or more factors in serum (1). These factors, which have been named somatomedins (2), are thought to be produced peripherally in response to growth hormone (1, 3). Part of the evidence for the involvement of growth hormone is the markedly lower stimulation of sulfation by serum from hypophysectomized rats (1,3,4) or hypopituitary humans (5-9) as compared to serum from normal individuals. Administration of purified growth hormone increased the titers of somatomedin in serum from hypopituitary rats (1, 3) or humans (6,7,9).We report here that in one system that has been used for assaying somatomedin, namely, cartilage from 12-day chick embryos (8, 10), somatomedin titers of serum from hypophysectomized rats were restored to values within or exceeding the normal range by addition in vitro of -3,5,3'-triiodothyronine (T3) at physiological concentrations. Addition of T3 to normal serum also increases its apparent somatomedin content. MATERIALS AND METHODST3 and L-thyroxine (T4) (Calbiochem) were dissolved in alkali and diluted rapidly in incubation medium before use. Bovine growth hormone was prepared according to Ellis (11) and Abbreviations: T3, I-3,5,3'-triiodothyronine; T4, L-thyroxine; NSILA, acid-soluble nonsuppressible insulin-like activity from serum.* To whom reprint requests should be addressed.purified by isoelectric focussing in a pH 7-9 gradient (12). Acid-soluble nonsuppressible insulin-like activity (NSILA), purified approximately 2000-fold from serum by acid ethanol extraction and chromatography on Sephadex G-75 (13), was a gift of Dr. E. R. Froesch. Purified relaxin (14) was provided by Dr. C. Schwabe.Hypophysectomized rats from which serum was obtained were operated on as weanlings and maintained for 6-8 weeks on a low-iodine diet, with or without daily maintenance doses of thyroid hormones, according to the protocol described by Denckla (15). In some gr...

show abstract

Mechanisms of stimulation of protein synthesis by thyroid hormones in vivo.

Cited by 69 publications

References 21 publications

The Action of Thyroid Hormone

The Action of Thyroid Hormone

Plasma Lecithin: Cholesterol Acyltransferase Activity in Hypo- and Hyperthyroidism

Enhancement of somatomedin titers of normal and hypopituitary sera by addition of L-triiodothyronone in vitro at physiological concentrations.

Contact Info

Product

Resources

About