title: Up-regulation of type II collagen gene by 17β-estradiol in articular chondrocytes involves Sp1/3, Sox-9, and estrogen receptor α.
abstract: The existence of a link between estrogen deprivation and osteoarthritis (OA) in postmenopausal women suggests that 17β-estradiol (17β-E2) may be a modulator of cartilage homeostasis. Here, we demonstrate that 17β-E2 stimulates, via its receptor human estrogen receptor α 66 (hERα66), type II collagen expression in differentiated and dedifferentiated (reflecting the OA phenotype) articular chondrocytes. Transactivation of type II collagen gene (COL2A1) by ligand-independent transactivation domain (AF-1) of hERα66 was mediated by "GC" binding sites of the -266/-63-bp promoter, through physical interactions between ERα, Sp1/Sp3, Sox9, and p300, as demonstrated in chromatin immunoprecipitation (ChIP) and Re-Chromatin Immuno-Precipitation (Re-ChIP) assays in primary and dedifferentiated cells. 17β-E2 and hERα66 increased the DNA-binding activities of Sp1/Sp3 and Sox-9 to both COL2A1 promoter and enhancer regions. Besides, Sp1, Sp3, and Sox-9 small interfering RNAs (siRNAs) prevented hERα66-induced transactivation of COL2A1, suggesting that these factors and their respective cis-regions are required for hERα66-mediated COL2A1 up-regulation. Our results highlight the genomic pathway by which 17β-E2 and hERα66 modulate Sp1/Sp3 heteromer binding activity and simultaneously participate in the recruitment of the essential factors Sox-9 and p300 involved respectively in the chondrocyte-differentiated status and COL2A1 transcriptional activation. These novel findings could therefore be attractive for tissue engineering of cartilage in OA, by the fact that 17β-E2 could promote chondrocyte redifferentiation.
  
  
  CONCLUSIONS
  17β-E2 up-regulates type II collagen gene expression in articular chondrocytes. An ERα66/Sp1/Sp3/Sox-9/p300 protein complex mediates this stimulatory effect. This heteromeric complex interacts and binds to Col2a1 promoter and enhancer in vivo. Our findings highlight a new regulatory mechanism for 17β-E2 action in chondrocytes. 17β-E2 might be an attractive candidate for cartilage engineering applications.
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France.
authors: Laure
authors: L
authors: Maneix
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France.
authors: Aurélie
authors: A
authors: Servent
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France.
authors: Benoît
authors: B
authors: Porée
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France.
authors: David
authors: D
authors: Ollitrault
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France.
authors: Thomas
authors: T
authors: Branly
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France.
authors: Nicolas
authors: N
authors: Bigot
authors: Laboratoire Endocrinologie Moléculaire de la Reproduction, Equipe Récepteurs des Oestrogènes et Destinée Cellulaire, CNRS UMR 6026, Université de Rennes I, 35042, Rennes, France.
authors: Noureddine
authors: N
authors: Boujrad
authors: Laboratoire Endocrinologie Moléculaire de la Reproduction, Equipe Récepteurs des Oestrogènes et Destinée Cellulaire, CNRS UMR 6026, Université de Rennes I, 35042, Rennes, France.
authors: Gilles
authors: G
authors: Flouriot
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France.
authors: Magali
authors: M
authors: Demoor
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France.
authors: Karim
authors: K
authors: Boumediene
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France.
authors: Safa
authors: S
authors: Moslemi
authors: Normandy University, Caen, France; UNICAEN, Laboratoire Microenvironnement Cellulaire et Pathologies (MILPAT), EA4652, 14032, Caen, France. philippe.galera@unicaen.fr.
authors: Philippe
authors: P
authors: Galéra
mesh_terms: D000818:Animals; D001665:Binding Sites; D002358:Cartilage, Articular / Q000166:cytology; D002454:Cell Differentiation; D019902:Chondrocytes / Q000166:cytology*; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D006801:Humans; D008297:Male; D010641:Phenotype; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000378:metabolism; D011817:Rabbits; D055758:SOX9 Transcription Factor / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D051705:Sp3 Transcription Factor / Q000378:metabolism*; D015533:Transcriptional Activation; D015854:Up-Regulation
chemical_list: C499177:COL2A1 protein, human; D024043:Collagen Type II; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D034741:RNA, Small Interfering; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; C108209:SP1 protein, human; D051705:Sp3 Transcription Factor; D004958:Estradiol
keywords: 17β-estradiol; Cartilage; Chondrocytes; Estrogen receptor α; Osteoarthritis; Sox proteins; Sp1/Sp3; Type II collagen (COL2A1) gene