Stimulation of GCMa transcriptional activity by cyclic AMP/protein kinase A signaling is attributed to CBP-mediated acetylation of GCMa.
Human GCMa is a zinc-containing transcription factor primarily expressed in placenta. GCMa regulates expression of syncytin gene, which encodes for a placenta-specific membrane protein that mediates trophoblastic fusion and the formation of syncytiotrophoblast layer required for efficient fetal-maternal exchange of nutrients and oxygen. The adenylate cyclase activator, forskolin, stimulates syncytin gene expression and cell fusion in cultured placental cells. Here we present evidence that cyclic AMP (cAMP) signaling pathway activates the syncytin gene expression by regulating GCMa activity. We found that forskolin and protein kinase A (PKA) enhances GCMa-mediated transcriptional activation. Furthermore, PKA treatment stimulates the association of GCMa with CBP and increases GCMa acetylation. CBP primarily acetylates GCMa at lysine367, lysine406, and lysine409 in the transactivation domain (TAD). We found that acetylation of these residues is required to protect GCMa from ubiquitination and increases the TAD stability with a concomitant increase in transcriptional activity, supporting the importance of acetylation in PKA-dependent GCMa activation. Our results reveal a novel regulation of GCMa activity by cAMP-dependent protein acetylation and provide a molecular mechanism by which cAMP signaling regulates trophoblastic fusion.
Chang
Ching-Wen
CW
Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei 115, Taiwan.
Chuang
Hsiao-Ching
HC
Yu
Chenchou
C
Yao
Tso-Pang
TP
Chen
Hungwen
H
D000107:Acetylation; D001665:Binding Sites; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation; D015686:Gene Products, env / Q000235:genetics / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D047468:Immunoprecipitation; D008239:Lysine / Q000737:chemistry; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism / Q000502:physiology*; D009687:Nuclear Proteins; D010100:Oxygen / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011257:Pregnancy Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014327:Trophoblasts / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D015854:Up-Regulation; D015032:Zinc / Q000737:chemistry
D004268:DNA-Binding Proteins; C491089:GCM1 protein, human; D015686:Gene Products, env; D009479:Neuropeptides; D009687:Nuclear Proteins; D011257:Pregnancy Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D025801:Ubiquitin; C405335:syncytin; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015032:Zinc; D008239:Lysine; D010100:Oxygen