The metabotropic GABAB receptor directly interacts with the activating transcription factor 4.
G protein-coupled receptors regulate gene expression by cellular signaling cascades that target transcription factors and their recognition by specific DNA sequences. In the central nervous system, heteromeric metabotropic gamma-aminobutyric acid type B (GABA(B)) receptors through adenylyl cyclase regulate cAMP levels, which may control transcription factor binding to the cAMP response element. Using yeast-two hybrid screens of rat brain libraries, we now demonstrate that GABA(B) receptors are engaged in a direct and specific interaction with the activating transcription factor 4 (ATF-4), a member of the cAMP response element-binding protein /ATF family. As confirmed by pull-down assays, ATF-4 associates via its conserved basic leucine zipper domain with the C termini of both GABA(B) receptor (GABA(B)R) 1 and GABA(B)R2 at a site which serves to assemble these receptor subunits in heterodimeric complexes. Confocal fluorescence microscopy shows that GABA(B)R and ATF-4 are strongly coclustered in the soma and at the dendritic membrane surface of both cultured hippocampal neurons as well as retinal amacrine cells in vivo. In oocyte coexpression assays short term signaling of GABA(B)Rs via G proteins was only marginally affected by the presence of the transcription factor, but ATF-4 was moderately stimulated in response to receptor activation in in vivo reporter assays. Thus, inhibitory metabotropic GABA(B)Rs may regulate activity-dependent gene expression via a direct interaction with ATF-4.
Nehring
R B
RB
Department of Molecular Neurobiology of Signal Transduction, Max Planck Institute for Biophysical Chemistry, 37070 Göttingen, Germany.
Horikawa
H P
HP
El Far
O
O
Kneussel
M
M
Brandstätter
J H
JH
Stamm
S
S
Wischmeyer
E
E
Betz
H
H
Karschin
A
A
D051701:Activating Transcription Factor 4; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004594:Electrophysiology; D004926:Escherichia coli / Q000378:metabolism; D005786:Gene Expression Regulation; D015723:Gene Library; D017930:Genes, Reporter; D005982:Glutathione Transferase / Q000378:metabolism; D007150:Immunohistochemistry; D008156:Luciferases / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D018080:Receptors, GABA-B / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012160:Retina / Q000378:metabolism; D012672:Semliki forest virus / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques; D014982:Xenopus laevis
C497110:Atf4 protein, rat; D018076:DNA, Complementary; D018080:Receptors, GABA-B; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D051701:Activating Transcription Factor 4; D000242:Cyclic AMP; D008156:Luciferases; D005982:Glutathione Transferase