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Activation of canonical wingless-type MMTV integration site family (Wnt) signaling in mature adipocytes increases beta-catenin levels and leads to cell dedifferentiation and insulin resistance.

ABSTRACT: Canonical Wnt ligands are secreted by several cell types in the adipose tissue. We examined if mature adipocytes can also be target cells and found that canonical Wnt activation by Wnt3a induced a marked dedifferentiation of both 3T3-L1 and human adipocytes. Typical adipogenic markers were reduced while undifferentiated cell markers like Pref-1/Dlk1, Wnt10b, and Gata2 were increased. The cells also became insulin-resistant with impaired upstream insulin signaling and reduced glucose uptake. Wnt3a stabilized beta-catenin in the absence of the LRP6 receptor and with maintained axin and Dickkopf-1 protein expression. PPARgamma was repressed and PPARgamma ligands could not restore the adipogenic markers or reduce the beta-catenin levels. The dedifferentiated adipocytes expressed the myofibroblast marker alpha-smooth muscle actin and were also susceptible to osteogenic transdifferentiation. These results identify a novel pathway in mature adipose cells that is critical for maintaining the normal adipocyte phenotype and insulin sensitivity.

SUBMITTER: Gustafson B

PROVIDER: S-EPMC2859564 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature

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Activation of canonical wingless-type MMTV integration site family (Wnt) signaling in mature adipocytes increases beta-catenin levels and leads to cell dedifferentiation and insulin resistance.

Gustafson Birgit B Smith Ulf U

The Journal of biological chemistry 20100223 18

Canonical Wnt ligands are secreted by several cell types in the adipose tissue. We examined if mature adipocytes can also be target cells and found that canonical Wnt activation by Wnt3a induced a marked dedifferentiation of both 3T3-L1 and human adipocytes. Typical adipogenic markers were reduced while undifferentiated cell markers like Pref-1/Dlk1, Wnt10b, and Gata2 were increased. The cells also became insulin-resistant with impaired upstream insulin signaling and reduced glucose uptake. Wnt3 ...[more]

PMID: 20179324

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Project description:Wnt proteins modulate cell proliferation and differentiation and the self-renewal of stem cells by inducing ?-catenin-dependent signalling through the Wnt receptor frizzled (FZD) and the co-receptors LRP5 and LRP6 to regulate cell fate decisions and the growth and repair of several tissues. The 19 mammalian Wnt proteins are cross-reactive with the 10 FZD receptors, and this has complicated the attribution of distinct biological functions to specific FZD and Wnt subtype interactions. Furthermore, Wnt proteins are modified post-translationally by palmitoylation, which is essential for their secretion, function and interaction with FZD receptors. As a result of their acylation, Wnt proteins are very hydrophobic and require detergents for purification, which presents major obstacles to the preparation and application of recombinant Wnt proteins. This hydrophobicity has hindered the determination of the molecular mechanisms of Wnt signalling activation and the functional importance of FZD subtypes, and the use of Wnt proteins as therapeutic agents. Here we develop surrogate Wnt agonists, water-soluble FZD-LRP5/LRP6 heterodimerizers, with FZD5/FZD8-specific and broadly FZD-reactive binding domains. Similar to WNT3A, these Wnt agonists elicit a characteristic ?-catenin signalling response in a FZD-selective fashion, enhance the osteogenic lineage commitment of primary mouse and human mesenchymal stem cells, and support the growth of a broad range of primary human organoid cultures. In addition, the surrogates can be systemically expressed and exhibit Wnt activity in vivo in the mouse liver, regulating metabolic liver zonation and promoting hepatocyte proliferation, resulting in hepatomegaly. These surrogates demonstrate that canonical Wnt signalling can be activated by bi-specific ligands that induce receptor heterodimerization. Furthermore, these easily produced, non-lipidated Wnt surrogate agonists facilitate functional studies of Wnt signalling and the exploration of Wnt agonists for translational applications in regenerative medicine.

Dataset Information

Activation of canonical wingless-type MMTV integration site family (Wnt) signaling in mature adipocytes increases beta-catenin levels and leads to cell dedifferentiation and insulin resistance.

Publications

Activation of canonical wingless-type MMTV integration site family (Wnt) signaling in mature adipocytes increases beta-catenin levels and leads to cell dedifferentiation and insulin resistance.

Similar Datasets

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