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Downregulation of Wnt-mediated ROS generation is causally implicated in leprechaunism
Ji Won Park1, Hye Sun Kuehn, So Youn Kim
1Department of Life Sciences, Ewha Womans University, Seoul, 120-750, Korea.
Abstract:
Although mutations in the insulin receptor have been causally implicated with leprechaunism, the full pathophysiology of the syndrome cannot be accounted for by malfunction of this gene alone. We sought to characterize a connection between Wnt-mediated cell signaling and the production of reactive oxygen species (ROS) which revealed a novel mechanistic basis for understanding the pathogenesis of leprechaunism. To identify candidate genes involved in this process, a PCR-based subtractive hybridization was performed. Candidate genes were examined for interaction with the Wnt signaling pathway and ROS generation. We found that Dickkopf 1 (Dkk1), a Wnt inhibitor, is overexpressed in skin fibroblast cells derived from three leprechaunism patients and that the cells showed an impaired response to Wnt2 in terms of beta-catenin-Tcf activation. Knockdown of Dkk1 in the patient cell lines rescued Wnt2-mediated Tcf activation. Concerted action of Wnt2 and knockdown of Dkk1 resulted in enhanced Nox4 expression and PDGF-induced ROS generation compared to parental patient cells. Furthermore, we found that NFATc2 was activated in response to Wnt2 stimulation and directly activates Nox4 expression. These data show a crosstalk between Wnt and ROS pathways which in turn provides new mechanistic insights at the molecular level into the pathogenesis of leprechaunism.
Insights
Leprechaunism involves more than insulin receptor mutations. This study reveals Wnt signaling and reactive oxygen species (ROS) crosstalk, identifying Dickkopf 1 (Dkk1) as a key factor in the disease.
Area of Science:
- Molecular Biology
- Cell Signaling
- Genetics
Background:
- Leprechaunism is linked to insulin receptor mutations, but its full pathology remains unclear.
- Understanding the interplay between cellular signaling pathways is crucial for deciphering complex genetic disorders.
Purpose of the Study:
- To investigate the connection between Wnt-mediated cell signaling and reactive oxygen species (ROS) production in leprechaunism.
- To identify novel molecular mechanisms underlying the pathogenesis of leprechaunism.
Main Methods:
- Utilized PCR-based subtractive hybridization to identify candidate genes.
- Examined gene interactions with Wnt signaling and ROS generation in patient-derived fibroblast cells.
- Performed Dickkopf 1 (Dkk1) knockdown experiments and analyzed beta-catenin-Tcf activation and Nox4 expression.
Main Results:
- Overexpression of Wnt inhibitor Dickkopf 1 (Dkk1) was observed in leprechaunism patient cells.
- Dkk1 knockdown restored Wnt2-mediated beta-catenin-Tcf activation.
- Wnt2 stimulation and Dkk1 knockdown enhanced Nox4 expression and ROS generation, involving NFATc2 activation.
Conclusions:
- Identified a novel crosstalk between Wnt signaling and ROS pathways in leprechaunism pathogenesis.
- Dickkopf 1 (Dkk1) plays a significant role in the molecular mechanisms of leprechaunism.
- Findings provide new mechanistic insights into leprechaunism at the molecular level.
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