Insulin regulates the expression of the insulin-like growth factor binding protein 2 mRNA in rat hepatocytes.
The goal of this study was to find out whether GH or insulin regulate the mRNA expression of the fetal binding protein of insulin-like growth factor (IGFBP-2). Primary hepatocytes from adult rats were used as a test system. IGFBP-2 mRNA was abundant in cells cultured in the absence of hormones and markedly reduced in cultures containing insulin. Addition of GH had no effect on IGFBP-2 mRNA levels although the cells are responsive to GH as demonstrated by a GH mediated elevation of IGF l mRNA levels. Half-maximal down-regulation of IGFBP-2 mRNA levels occurred at an insulin concentration of 1 to 2 x 10(-10) M. The finding that insulin is a potent negative regulator of hepatic IGFBP-2 mRNA levels suggests a physiologically important regulatory link between the two hormones insulin and IGF l.
Metabolic Unit, University Hospital, Zürich, Switzerland.
M
M
Böni-Schnetzler
C
C
Schmid
J L
JL
Mary
B
B
Zimmerli
P J
PJ
Meier
J
J
Zapf
J
J
Schwander
E R
ER
Froesch
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects*; D013006:Growth Hormone / Q000494:pharmacology; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D018969:Insulin-Like Growth Factor Binding Proteins; D008099:Liver / Q000378:metabolism*; D008297:Male; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D002352:Carrier Proteins; D007328:Insulin; D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D013006:Growth Hormone