Genetic regulation of beta 2-adrenergic receptors in 3T3-L1 fibroblasts.
The beta 2-adrenergic receptor from mouse 3T3-L1 cells is up-regulated through genetic mechanisms by glucocorticoids and butyrate. To study the genetic regulation of these receptors, we sequenced a 5 kb region of genomic DNA from 3T3-L1 cells, containing the beta-adrenergic receptor gene and approx. 1.5 kb of both 5' and 3' flanking sequences. The sequence contained one copy of an 8 bp consensus sequence which can confer phorbol ester-responsiveness to genes. Phorbol esters attenuated the up-regulation of beta 2-adrenergic receptors by glucocorticoids but not by butyrate. This effect was probably due to a phorbol ester-induced decrease in glucocorticoid receptor number. Using methylation-sensitive restriction enzymes, we examined the methylation of a CG-rich region occurring 5' to the gene and did not detect any changes in methylation of this region upon dexamethasone or butyrate treatment. A total of 16 putative glucocorticoid response elements were found which may mediate the glucocorticoid-induced increase in beta 2-adrenergic receptors. A comparison of the regulatory sequences of the two beta-adrenergic receptor subtypes from human and mouse confirms the observed physiological controls of receptor subtype expression and offers an explanation as to why the subtypes differ in genetic regulation.
Nakada
M T
MT
Department of Pharmacology, University of Pennsylvania, Philadelphia 19104.
Haskell
K M
KM
Ecker
D J
DJ
Stadel
J M
JM
Crooke
S T
ST
D000818:Animals; D001483:Base Sequence; D002087:Butyrates / Q000494:pharmacology; D020148:Butyric Acid; D002478:Cells, Cultured; D004247:DNA; D003907:Dexamethasone / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D008745:Methylation; D051379:Mice; D008969:Molecular Sequence Data; D015240:Phorbol 12,13-Dibutyrate; D011943:Receptors, Adrenergic, beta / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid
D002087:Butyrates; D011943:Receptors, Adrenergic, beta; D020148:Butyric Acid; D015240:Phorbol 12,13-Dibutyrate; D003907:Dexamethasone; D004247:DNA