Palladin's Ig4 Mutation: Exploring the link with pancreatic cancer

Click on the DOI link to access the article (may not be free).Palladin is a recently discovered protein that is expressed in human cells and plays a key role in cytoskeletal dynamics by directly binding and bundling filaments of actin. These processes provide an important function in cell motility and are made possible by the Ig3 and Ig4 domains of palladin. Since cancer survival is often dependent upon migration of cancerous cells to other parts of the body, palladin has been implicated as playing a critical role in cancer metastasis. In addition, a mutation from a conserved tryptophan to cysteine in palladin's Ig4 domain has recently been linked to a form of pancreatic cancer. This mutation is called “PaTu2,” and understanding how it affects palladin is the focus of this research project. We began by isolating the wild type and mutant Ig4 and Ig3-4 domains of palladin. Obtaining the PaTu2 mutant protein required a different approach due to the protein remaining insoluble within inclusion bodies in E. coli bacteria after cell lysis. This was amended by incorporating a maltose-binding protein tag to increase solubility so that the protein could undergo affinity purification. Next, we determined whether the mutation affected palladin's ability to bind and bundle actin filaments by conducting cosedimentation assays, with initial results showing no significant difference when compared to the wild-type. Future directions of the project include using nuclear magnetic resonance and circular dichroism spectroscopy to see if the mutation affects the structure and stability of palladin. Such analysis will provide the necessary data that lead towards a greater understanding the cause of metastatic pancreatic cancer