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We have previously shown that Wnt5A-mediated signaling can promote melanoma metastasis. It has been shown that Wnt signaling is antagonized by the protein Klotho, which has been implicated in aging. We show here that in melanoma cells, expressions of Wnt5A and Klotho are inversely correlated. In the presence of recombinant Klotho (rKlotho), we show that Wnt5A internalization and signaling is decreased in high Wnt5A-expressing cells. Moreover, in the presence of rKlotho, we observe an increase in Wnt5A remaining in the medium, coincident with an increase in sialidase activity, and decrease in syndecan expression. These effects can be inhibited using a sialidase inhibitor. In addition to its effects on Wnt5A internalization, we also demonstrate that Klotho decreases melanoma cell invasive potential by a second mechanism that involves the inhibition of calpain and a resultant decrease in filamin cleavage, which we demonstrate is critical for melanoma cell motility. [ABSTRACT FROM AUTHOR]

Heparan sulfate proteoglycans (HSPGs) are important modulators for optimizing signal transduction of many pathways, including the Wnt pathways. We demonstrate that HSPG glycosaminoglycan levels increased with increasing metastatic potential of melanoma cells. Previous studies have demonstrated that Wnt5A increases the invasiveness of melanoma cells. We further demonstrate that HSPGs potentiate Wnt5A signaling, since enzymatic removal of the HSPG backbone resulted in a decrease in cellular Wnt5A levels, an increase in secreted Wnt5A in cell media, a decrease in downstream signaling, and ultimately, a decrease in invasiveness. Specifically, syndecan 1 and syndecan 4 expression correlated to Wnt5A expression and melanoma malignancy. Knockdown of syndecan 1 or 4 caused decreases in cell invasion, which could be restored by treating the cells with recombinant Wnt5A. These data indicate that syndecan 1 and 4 correlate to increased metastatic potential in melanoma patients and are an important component of the Wnt5A autocrine signaling loop, the activation of which leads to increased metastasis of melanoma. [ABSTRACT FROM AUTHOR]

We have previously shown that Wnt5A and ROR2, an orphan tyrosine kinase receptor, interact to mediate melanoma cell motility. In other cell types, this can occur through the interaction of ROR2 with the cytoskeletal protein filamin A. Here, we found that filamin A protein levels correlated with Wnt5A levels in melanoma cells. Small interfering RNA (siRNA) knockdown of WNT5A decreased filamin A expression. Knockdown of filamin A also corresponded to a decrease in melanoma cell motility. In metastatic cells, filamin A expression was predominant in the cytoplasm, which western analysis indicated was due to the cleavage of filamin A in these cells. Treatment of nonmetastatic melanoma cells with recombinant Wnt5A increased filamin A cleavage, and this could be prevented by the knockdown of ROR2 expression. Further, BAPTA-AM chelation of intracellular calcium also inhibited filamin A cleavage, leading to the hypothesis that Wnt5A/ROR2 signaling could cleave filamin A through activation of calcium-activated proteases, such as calpains. Indeed, WNT5A knockdown decreased calpain 1 expression, and by inhibiting calpain 1 either pharmacologically or using siRNA, it decreased cell motility. Our results indicate that Wnt5A activates calpain-1, leading to the cleavage of filamin A, which results in a remodeling of the cytoskeleton and an increase in melanoma cell motility.Journal of Investigative Dermatology (2009) 129, 1782–1789; doi:10.1038/jid.2008.433; published online 29 January 2009 [ABSTRACT FROM AUTHOR]

OBJECTIVE--The aim of this study was to find an effective treatment for the genetic form of diabetes that is present in some Huntington's disease patients and in Huntington's disease mouse models. Huntington's disease is a neurodegenerative disorder caused by a polyglutamine expansion within the huntingtin protein. Huntington's disease patients exhibit neuronal dysfunction/degeneration, chorea, and progressive weight loss. Additionally, they suffer from abnormalities in energy metabolism affecting both the brain and periphery. Similarly to Huntington's disease patients, mice expressing the mutated human huntingtin protein also exhibit neurodegenerative changes, motor dysfunction, perturbed energy metabolism, and elevated blood glucose levels. RESEARCH DESIGN AND METHODS--Huntington's disease mice were treated with an FDA-approved antidiabetic glucagonlike peptide 1 receptor agonist, exendin-4 (Ex-4), to test whether euglycemia could be achieved, whether pancreatic dysfunction could be alleviated, and whether the mice showed any neurological benefit. Blood glucose and insulin levels and various appetite hormone concentrations were measured during the study. Additionally, motor performance and life span were quantified and mutant huntingtin (mhtt) aggregates were measured in both the pancreas and brain. RESULTS--Ex-4 treatment ameliorated abnormalities in peripheral glucose regulation and suppressed cellular pathology in both brain and pancreas in a mouse model of Huntington's disease. The treatment also improved motor function and extended the survival time of the Huntington's disease mice. These clinical improvements were correlated with reduced accumulation of mhtt protein aggregates in both islet and brain cells. CONCLUSIONS--Targeting both peripheral and neuronal deficits, Ex-4 is an attractive agent for therapeutic intervention in Huntington's disease patients suffering from diabetes. Diabetes 58:318-328, 2009 [ABSTRACT FROM AUTHOR]