The effect of population density on phenylalanine hydroxylase activity in rat-hepatoma cells in culture

1974 ◽  
Vol 40 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Donald F. Haggerty ◽  
Peggy L. Young ◽  
James V. Buese
1989 ◽  
Vol 67 (6) ◽  
pp. 293-296 ◽  
Author(s):  
Michael A. Parniak ◽  
Janice Pilkington

Incubation of H4-II-E-C3 rat hepatoma cells with either hydrocortisone or dexamethasone resulted in 3- to 5-fold increases in the levels of both phenylalanine hydroxylase and its essential cofactor, tetrahydrobiopterin. Maximum elevation of phenylalanine hydroxylase was noted after 24 h of incubation, whereas significant increases in tetrahydrobiopterin were found only after 48 h exposure of the cells to glucocorticoids. Removal of hormone from the culture medium resulted in rapid loss of cell tetrahydrobiopterin, but a much slower decline in the level of phenylalanine hydroxylase. Thus, although the levels of both phenylalanine hydroxylase and tetrahydrobiopterin in rat hepatoma cells are regulated by glucocorticoids, this regulation is apparently not strictly coordinated. Nevertheless, control of cellular tetrahydrobiopterin levels may be an important regulator of hepatic phenylalanine catabolism since significant increases in the ability of intact rat liver cells to hydroxylate phenylalanine were observed only after 48 h exposure to glucocorticoids, in correlation with increases in cell tetrahydrobiopterin content.Key words: phenylalanine hydroxylase, tetrahydrobiopterin, glucocorticoid, hepatoma cells.


1977 ◽  
Vol 109 (2) ◽  
pp. 371-379 ◽  
Author(s):  
R. van Wijk ◽  
K.W. van de Poll ◽  
W.J.C. Amesz ◽  
W.L.M. Geilenkirchen

1986 ◽  
Vol 30 (3) ◽  
pp. 229-236 ◽  
Author(s):  
Edith Rogier ◽  
Doris Cassio ◽  
Mary C. Weiss ◽  
Gerard Feldmann

1976 ◽  
Vol 151 (4) ◽  
pp. 789-794 ◽  
Author(s):  
Y. Goto ◽  
C. A. Dujovne ◽  
D. W. Shoeman ◽  
K. Arakawa

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