Dataset Information

?-Catenin independent cross-control between the estradiol and Wnt pathways in osteoblasts.

ABSTRACT: Osteoblasts are controlled by the individual and combined effects of systemic and local growth regulators. Here we show functional and physical interactions between estradiol (17?E) and Wnt activated pathways in osteoblasts. 17?E increased gene promoter activity by the Wnt pathway transcriptional effector T cell factor (TCF) in an estrogen receptor (ER) dependent way. This occurred independently of its activity through traditional estrogen response elements and was not replicated by androgen receptor activation. 17?E also increased the stimulatory effect of LiCl on TCF activity, LiCl increased the stimulatory effect of 17?E through estrogen response elements, and both were further enhanced by a noncanonical Wnt receptor agonist (WAg) that functions independently of ?-catenin stabilization. In contrast to LiCl, WAg increased DNA synthesis and reduced relative collagen synthesis and alkaline phosphatase activity in otherwise untreated or 17?E stimulated cells. In addition, WAg suppressed Runx2, osterix, and alkaline phosphatase mRNA levels, and potently induced osteoprotegerin mRNA, whereas LiCl was ineffective alone and inhibitory in combination with 17?E. A definitive intersection between the 17?E and Wnt pathways occurred at the protein level, where ER? physically associated with TCF-4 independently of its ?-catenin binding domain. This interaction required ligand-dependent exposure of a TCF binding region that mapped to ER? domain E and was further enhanced by Wnt pathway activation. Our studies reveal highly focused co-regulatory effects between the 17?E and Wnt pathways in osteoblasts that involve activated ER? and TCF-4 and downstream changes in gene expression, osteoblast proliferation, and differentiated cell function.

SUBMITTER: McCarthy TL

PROVIDER: S-EPMC3094493 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

β-Catenin independent cross-control between the estradiol and Wnt pathways in osteoblasts.

McCarthy Thomas L TL Kallen Caleb B CB Centrella Michael M

Gene 20110216 1-2

Osteoblasts are controlled by the individual and combined effects of systemic and local growth regulators. Here we show functional and physical interactions between estradiol (17βE) and Wnt activated pathways in osteoblasts. 17βE increased gene promoter activity by the Wnt pathway transcriptional effector T cell factor (TCF) in an estrogen receptor (ER) dependent way. This occurred independently of its activity through traditional estrogen response elements and was not replicated by androgen rec ...[more]

PMID: 21335072

Similar Datasets

Project description:ObjectiveClinical and in vitro studies suggest that subchondral bone sclerosis due to abnormal osteoblasts (Ob) is involved in the progression and/or onset of osteoarthritis (OA). Human Ob isolated from sclerotic subchondral OA bone tissue show an altered phenotype, a decreased canonical Wnt/?-catenin signaling pathway (cWnt), and a reduced mineralization in vitro. In addition to the cWnt pathway, at least two non-canonical signaling pathways, the Wnt/PKC and Wnt/PCP pathway have been described. However, there are no reports of either pathway in OA Ob. Here, we studied the two non-canonical pathways in OA Ob and if they influence their phenotype.MethodsHuman primary subchondral Ob were isolated from the subchondral bone plate of tibial plateaus of OA patients undergoing total knee arthroplasty, or of normal individuals at autopsy. The expression of genes involved in non-canonical Wnt signaling was evaluated by qRT-PCR and their protein production by Western blot analysis. Alkaline phosphatase activity and osteocalcin secretion (OC) were determined with substrate hydrolysis and EIA, respectively. Mineralization levels were evaluated with Alizarin Red Staining, Wnt/PKC and Wnt/PCP pathways by target gene expression and their respective activity using the NFAT and AP-1 luciferase reporter assays.ResultsOA Ob showed an altered phenotype as illustrated by an increased alkaline phosphatase activity and osteocalcin release compared to normal Ob. The expression of the non-canonical Wnt5a ligand was increased in OA Ob compared to normal. Whereas, the expression of LGR5 was significantly increased in OA Ob compared to normal Ob, the expression of LGR4 was similar. Wnt5a directly stimulated the expression and production of LGR5, contrasting, Wnt5a did not stimulate the expression of LGR4. Wnt5a also stimulated the phosphorylation of both JNK and PKC, as well as the activity of both NFAT and AP-1 transcription factors. The inhibition of Wnt5a expression partially corrects the abnormal mineralization, OC secretion and ALPase activity of OA Ob.ConclusionThese data indicate that the alteration of Wnt5a, a non-canonical Wnt signaling activator, is implicated in the modified signalisation and phenotype observed in OA Ob.

Dataset Information

?-Catenin independent cross-control between the estradiol and Wnt pathways in osteoblasts.

Publications

β-Catenin independent cross-control between the estradiol and Wnt pathways in osteoblasts.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets