Developmental and glucocorticoid modulation of the expression of mRNAs for Gs alpha and G beta subunits in neonatal liver.
The mRNA levels for Gs alpha and G beta in liver from various age groups of rabbits were assessed by Northern and dot-blot hybridization assays using cDNA and oligonucleotide probes. The mRNA levels for both Gs alpha and G beta exhibited a transient 30-35% decrease at 3-6 h after birth, followed by a 3- to 3.5-fold increase which peaked at 2 days after birth, then gradually declined to adult levels at 4-6 weeks. The changes in mRNA levels paralleled the changes in protein levels [previously measured by immunoblotting (Kawai and Arinze, 1991)] in the first 2 days after birth, but not in the later periods of development. Beyond day 3, the increase in protein levels persists, reaching maximal levels at 4 weeks and equalling adult levels while their mRNA levels decrease to about 50% of the levels at day 2. In vivo administration of dexamethasone to neonatal rabbits increased hepatic mRNA levels for both Gs alpha and G beta by about 50%; the effect was moderate compared to the 2- to 3-fold increase in corresponding protein levels. The transcription rate for the Gs alpha gene increased by only 32% at day 2 after birth compared to term. A 68% increase in transcription rate for this gene was observed after the dexamethasone treatment. Taken together, these data indicate that the developmental and glucocorticoid-regulated expression of Gs alpha- and G beta-subunits in neonatal liver is modulated at the transcriptional level.
Jiang
P
P
Department of Biochemistry, Meharry Medical College, Nashville, TN 37208.
Arinze
I J
IJ
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D008099:Liver / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D011817:Rabbits; D014158:Transcription, Genetic / Q000187:drug effects
D018076:DNA, Complementary; D012333:RNA, Messenger; D003907:Dexamethasone; D019204:GTP-Binding Proteins