The effect of vanadate upon the expression of phenylalanine hydroxylase in streptozotocin-diabetic rat liver.
Induction of diabetes in rats is associated with a significant elevation in the phenylalanine hydroxylating capacity of the liver. This phenomenon reflects an increase in the abundance of both phenylalanine hydroxylase protein and phenylalanine hydroxylase-specific mRNA. These changes can be abolished by insulin-dependent control of diabetes. We show here that the control of diabetes by oral administration of sodium orthovanadate will also nullify the diabetes-related alterations in phenylalanine hydroxylase expression. In addition, diabetes-induced changes in the extent of phosphorylation of phenylalanine hydroxylase are reversed by either insulin or vanadate treatment in vivo. These treatments also abolished the diabetes-related, approx. 30-fold, decrease in glucagon sensitivity of phenylalanine hydroxylation in isolated liver cells.
Green
A K
AK
Department of Biochemistry, University of Liverpool, UK.
McDowall
I L
IL
Richardson
S C
SC
Fisher
M J
MJ
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D005934:Glucagon / Q000494:pharmacology; D006900:Hydroxylation; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D010651:Phenylalanine Hydroxylase / Q000096:biosynthesis* / Q000235:genetics; D010766:Phosphorylation; D012313:RNA / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D013311:Streptozocin; D014638:Vanadates / Q000494:pharmacology*
D014638:Vanadates; D013311:Streptozocin; D012313:RNA; D005934:Glucagon; D010651:Phenylalanine Hydroxylase