Tyrosine aminotransferase induction in hepatocytes cultured from rat foetuses treated with dexamethasone <i>in utero</i>

Yeoh, George C.T.; Arbuckle, Tye E.; Oliver, I.T.

doi:10.1042/bj1800545

Cited by 28 publications

(3 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…mASAT, mitochondria1 aspartate aminotransferase. coids (37). In the case of our patients, the situation is similar to that in fetal and premature neonatal liver.…”

supporting

confidence: 61%

Persistent Tyrosinemia Associated with Low Activity of Tyrosine Aminotransferase

et al. 1984

View full text Add to dashboard Cite

SummaryA son of related Turkish parents had grossly elevated serum tyrosine concentration and excreted tyrosine and p-hydroxyphenolic acids into the urine, whereas neither succinylacetone nor succinylacetoacetate could be demonstrated. The tyrosine concentration was normalized by a proper diet. This was not followed strictly at home. During the first 2 years of life, the patient had severe undulating nystagmus that disappeared later. No skin lesions were present and there was only slight corneal clouding of the eyes. At the age of 5, the patient had attained the maturity of a 4-year-old, showing a balanced profile.Specific tyrosine aminotransferase (EC 2.6.1.5) was present in the liver; the K, value for tyrosine was normal. However, the total activity was less than 10% of normal, a situation similar to that observed in fetal human liver. A younger sister of the patient also has tyrosinemia and low hepatic tyrosine aminotransferase activity.

show abstract

“…mASAT, mitochondria1 aspartate aminotransferase. coids (37). In the case of our patients, the situation is similar to that in fetal and premature neonatal liver.…”

supporting

confidence: 61%

Persistent Tyrosinemia Associated with Low Activity of Tyrosine Aminotransferase

et al. 1984

View full text Add to dashboard Cite

show abstract

“…The enzymatic differentiation of developing rat liver has proved to be a useful model for these studies. During development, most rat liver enzymes accumulate rapidly and in discrete groups or clusters: the late fetal cluster (16)(17)(18)(19)(20)(21)(22) days ofgestation), the neonatal cluster, and the late suckling cluster (1).…”

mentioning

confidence: 99%

Induction of tyrosine aminotransferase mRNA by glucocorticoids and cAMP in fetal rat liver.

Ruiz-Bravo¹,

Ernest²

1982

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

View full text Add to dashboard Cite

Tyrosine aminotransferase (L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5) enzyme and mRNA activity were not detectable in day 20 fetal rat liver. Precocious induction of catalytic activity by in utero injection of dibutyryl cAMP was a direct consequence ofthe de novo appearance oftranslatable tyrosine aminotransferase mRNA. In contrast, in utero injection ofhydrocortisone acetate failed to elicit fetal liver enzyme activity. This failure was due to the inability of the steroid hormone to induce the appearance of tyrosine aminotransferase mRNA activity. In fetal rat liver explants, either compound was capable of stimulating the synthesis of adult levels of enzyme and mRNA. However, catalytic and mRNA activity comparable with that seen in vivo 24 hr after birth required the concerted action of both inducers.One of the central problems in the study of development is the determination of the factors responsible for differential gene expression and the appearance of tissue-specific proteins. The enzymatic differentiation of developing rat liver has proved to be a useful model for these studies. During development, most rat liver enzymes accumulate rapidly and in discrete groups or clusters: the late fetal cluster (16-22 days ofgestation), the neonatal cluster, and the late suckling cluster (1).Tyrosine aminotransferase (L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5) is one of the enzymes appearing in the neonatal cluster (1). Enzyme activity, virtually absent in fetal rat liver, starts to increase 2 hr after birth, reaching a maximum of at least twice the adult level by 12 hr. The catalytic activity then decreases to adult level by 2 days after birth (2, 3). Premature appearance of tyrosine aminotransferase can be elicited in fetal rats by in utero injection of glucagon (4, 5) or dibutyryl cAMP (6); glucocorticoid injection does not precociously induce catalytic activity (4, 6). However, all three compounds induce enzyme activity in vitro (7-9).As part of our studies on the regulation of tyrosine aminotransferase gene expression, we are investigating the process responsible for the appearance of tyrosine aminotransferase in newborn rats. We present evidence that the appearance of enzyme activity after precocious induction in utero is a direct consequence of the de novo accumulation of mRNA coding for tyrosine aminotransferase. In addition, we have used fetal rat liver explants to correlate tyrosine aminotransferase mRNA and enzyme activity during induction by dibutyryl cAMP and hydrocortisone acetate.MATERIALS AND METHODS Chemicals. Cortef acetate (hydrocortisone acetate, 50 mg/ ml) was provided by Upjohn. BGJb medium, Fitton-Jackson modification, and penicillin/streptomycin (penicillin, 10,000 units/ml; streptomycin, 10,000 Ag/ml) were from GIBCO.Translation grade [3S]methionine (specific activity, 1350-1450 Ci/mmol; 1 Ci = 3.7 X 101°becquerels) was from Amersham. Cordycepin, protein A-Sepharose, and other biochemicals were from Sigma.Animals. Sprague-Dawley (CD) rats from Charles River Br...

show abstract

“…This assumption was supported by results of previous work which demonstrated that premature delivery of fetuses of rats and other experimental animal species, or administration of either glucagon or dibutyryl-CAMP to rat fetuses in utero resulted in the precocious appearance of the enzyme in the liver (Litwack and Nemeth, 1965;Greengard and Dewey, 1967;Holt and Oliver, 1968;Greengard, 1969). Similarly, TAT activity has also been observed both in fetal liver explants ( Ruiz-Bravo and Ernest, 1982) and in monolayer cultures (Yeoh et al, 1979a(Yeoh et al, , 1979b. Together, the results were interpreted to mean that the environment in utero might be responsible for suppressing the synthesis of TAT in the fetal liver (Cake et al, 1989).…”

Section: Discussionmentioning

confidence: 88%

Precocious induction of tyrosine aminotransferase mRNA by hydrocortisone in cultured fetal rat hepatocytes at different developmental stages

Hoffmann

Paul

1990

Journal Cellular Physiology

View full text Add to dashboard Cite

Tyrosine-aminotransferase (TAT) is encoded by a liver-specific gene known to be expressed perinatally. Fetal rat hepatocytes (gestation day 19) in primary cultures, in which TAT gene expression is normally undetectable, are induced by hydrocortisone to express TAT-mRNA in a dose-dependent manner (greater than 10(-7) M). In hepatocytes incubated with hydrocortisone, TAT-mRNA levels were marginal after 24 hours, reaching maximal levels at 48 hours. After a pre-incubation of hepatocytes for 24 hours in the absence of hydrocortisone followed by exposure to hydrocortisone (24-48 hours). TAT-mRNA levels were high. Hepatocytes derived from fetuses of gestation days 14 and 17 displayed comparable levels of TAT-mRNA in response to hydrocortisone. These results demonstrate that cultured hepatocytes of gestational stages as early as day 14, which initially do not respond to hydrocortisone by TAT gene induction, undergo a "maturation" process during the initial 24 hours following cultivation, resulting in the acquisition of precocious competence for TAT gene transcription in response to hydrocortisone. This suggests that one or more factor(s), required for hydrocortisone-inducible TAT gene transcription, and not available in fetal liver until birth (Gluecksohn-Waelsch: Cell, 18:225-237, 1979) appear in fetal hepatocytes upon cultivation during this "maturation" period, thus permitting precocious TAT gene expression in vitro.

show abstract

Tyrosine aminotransferase induction in hepatocytes cultured from rat foetuses treated with dexamethasone in utero

Cited by 28 publications

References 20 publications

Persistent Tyrosinemia Associated with Low Activity of Tyrosine Aminotransferase

Persistent Tyrosinemia Associated with Low Activity of Tyrosine Aminotransferase

Induction of tyrosine aminotransferase mRNA by glucocorticoids and cAMP in fetal rat liver.

Precocious induction of tyrosine aminotransferase mRNA by hydrocortisone in cultured fetal rat hepatocytes at different developmental stages

Contact Info

Product

Resources

About