Regulation of the hyaluronan synthase 2 gene by convergence in cyclic AMP response element-binding protein and retinoid acid receptor signaling.
The human hyaluronan synthase 2 (HAS2) gene encodes for an enzyme making hyaluronan, altered concentrations of which are associated with many pathological situations including wounding, several inflammatory conditions, and malignant tumors. In this study we showed that HAS2 is a primary target of the cAMP activator forskolin and the nuclear hormone all-trans-retinoic acid (RA). The first 2250 bp of the promoter contain three response elements (REs) for the transcription factor CREB1 as well as two REs for the nuclear receptor RAR. Chromatin immunoprecipitation and re-chromatin immunoprecipitation assays using selected fragments of the promoter containing the putative REs showed that forskolin and all-trans-RA modulate the formation of complexes between CREB1 and RAR with various co-regulators at the predicted sites. Interestingly, CREB1 complexes are regulated by all-trans-RA as are RAR complexes by forskolin. Reporter gene assays using nested promoter fragments supported these findings. Forskolin and all-trans-RA co-stimulation reduced the binding of CREB1, RAR, and the co-repressor nuclear receptor co-repressor 1 (NCoR1), but enhanced the association of co-activators MED1 and CREB-binding protein (CBP). RNA interference experiments suggested that MED1 and NCoR1 are central for the all-trans-RA induction of the HAS2 gene and CBP dominates its forskolin response. In general, our findings suggest a convergence of CREB1 and RAR signaling, and demonstrate the individual character of each RE in terms of co-regulator use.
Department of Bioscience, of Kuopio, FIN-70211 Kuopio, Finland.
Katri M
KM
Makkonen
Sanna
S
Pasonen-Seppänen
Kari
K
Törrönen
Markku I
MI
Tammi
Carsten
C
Carlberg
D015153:Blotting, Western; D002461:Cell Line, Transformed; D005576:Colforsin / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D014453:Glucuronosyltransferase / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D000076002:Hyaluronan Synthases; D015603:Keratinocytes / Q000166:cytology / Q000502:physiology*; D007668:Kidney / Q000166:cytology; D056913:Mediator Complex Subunit 1; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D056971:Nuclear Receptor Co-Repressor 1; D011401:Promoter Regions, Genetic / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering; D018168:Receptors, Retinoic Acid / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology; D000097768:Retinoic Acid Receptor gamma
D005576:Colforsin; D017362:Cyclic AMP Response Element-Binding Protein; D014453:Glucuronosyltransferase; D000076002:Hyaluronan Synthases; D056913:Mediator Complex Subunit 1; D009687:Nuclear Proteins; D056971:Nuclear Receptor Co-Repressor 1; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; D014157:Transcription Factors; D014212:Tretinoin; D000097768:Retinoic Acid Receptor gamma; C115163:CREB1 protein, human; C538855:MED1 protein, human; C539127:NCOR1 protein, human; C101754:HAS2 protein, human