A Fos-Jun element in the first intron of an alpha 2u-globulin gene.
The hepatic expression of the alpha-2u-globulin gene family is controlled by a variety of hormones including steroids, growth hormone and insulin. The mechanisms by which these hormones affect alpha 2u-globulin expression are only partially understood. Recently we isolated and characterized clone RAP 01, an alpha 2u-globulin gene expressed in the liver. In preliminary experiments we noted that partial hepatectomy, a procedure which results in a sharp rise in the level of the oncoproteins c-Fos and c-Jun, also causes a transient induction of the messenger RNA corresponding to clone RAP 01. Using the DNAseI footprinting technique we were able to show that this clone contains a TPA (phorbol 12-myristate 13-acetate)-responsive element (TRE) in its first intron. This element (denoted as element X) is identical to the consensus AP-1 binding site (TGACTCAG) and is protected by rat liver nuclear extracts as well as by purified c-Jun. Gel retardation experiments show that an oligonucleotide containing the TRE consensus sequence competes for binding of liver nuclear proteins to element X and that antibodies directed against the M2 peptide of the mouse Fos protein or the PEP-2 peptide of Jun prevent the formation of specific complexes with the same element. Moreover, element X functions as a TRE in transfected BWTG3 hepatoma cells treated with TPA. Co-transfection with fos and jun expression vectors mimics the effects of TPA suggesting that AP-1 is in fact the mediator of the observed response. It is concluded that the first intron of RAP 01 contains a functional Fos-Jun element.
van Dijck
P
P
Department of Developmental Biology, Campus Gasthuisberg, Leuven, Belgium.
Schoonjans
K
K
Sassone-Corsi
P
P
Auwerx
J
J
Verhoeven
G
G
D000510:Alpha-Globulins / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D003850:Deoxyribonuclease I; D007438:Introns; D008099:Liver / Q000502:physiology; D008969:Molecular Sequence Data; D005810:Multigene Family; D009687:Nuclear Proteins / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000510:Alpha-Globulins; D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; C013803:alpha 2u globulin; D003850:Deoxyribonuclease I; D013755:Tetradecanoylphorbol Acetate