GA-binding protein and p300 are essential components of a retinoic acid-induced enhanceosome in myeloid cells.
Expression of CD18, the beta chain of the leukocyte integrins, is transcriptionally regulated by retinoic acid (RA) in myeloid cells. Full RA responsiveness of the CD18 gene requires its proximal promoter, which lacks a retinoic acid response element (RARE). Rather, RA responsiveness of the CD18 proximal promoter requires ets sites that are bound by GA-binding protein (GABP). The transcriptional coactivator, p300, further increases CD18 RA responsiveness. We demonstrate that GABPalpha, the ets DNA-binding subunit of GABP, physically interacts with p300 in myeloid cells. This interaction involves the GABPalpha pointed domain (PNT) and identifies p300 as the first known interaction partner of GABPalpha PNT. Expression of the PNT domain, alone, disrupts the GABPalpha-p300 interaction and decreases the RA responsiveness of the CD18 proximal promoter. Chromatin immunoprecipitation and chromosome conformation capture demonstrate that, in the presence of RA, GABPalpha and p300 at the proximal promoter recruit retinoic acid receptor/retinoid X receptor from a distal RARE to form an enhanceosome. A dominant negative p300 construct disrupts enhanceosome formation and reduces the RA responsiveness of CD18. Thus, proteins on the CD18 proximal promoter recruit the distal RARE in the presence of RA. This is the first description of an RA-induced enhanceosome and demonstrates that GABP and p300 are essential components of CD18 RA responsiveness in myeloid cells.
Dept. of Molecular Biology, Brown University, Rhode Island Hospital, Providence, RI 02903, USA.
Karen K
KK
Resendes
Alan G
AG
Rosmarin
D001665:Binding Sites; D018821:CD18 Antigens / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050881:E1A-Associated p300 Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004742:Enhancer Elements, Genetic; D051268:GA-Binding Protein Transcription Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008957:Models, Genetic; D022423:Myeloid Cells / Q000187:drug effects / Q000378:metabolism*; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic / Q000187:drug effects; D017434:Protein Structure, Tertiary; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D047488:Retinoid X Receptors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015533:Transcriptional Activation / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology*; D020298:U937 Cells
D018821:CD18 Antigens; D004268:DNA-Binding Proteins; D051268:GA-Binding Protein Transcription Factor; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014212:Tretinoin; D050881:E1A-Associated p300 Protein