Calmodulin-like Protein Increases Filopodia-dependent Cell Motility via Up-regulation of Myosin-10

Amy S. Mauer,Richard D. Bennett,Emanuel E. Strehler

doi:10.1074/jbc.m607174200

Abstract

Human calmodulin-like protein (CLP) is an epithelial-specific protein that is expressed during cell differentiation but down-regulated in primary cancers and transformed cell lines. Using stably transfected and inducible HeLa cell lines, we found that CLP expression did not alter the proliferation rate and colony-forming potential of these cells. However, remarkable phenotypic changes were observed in CLP-expressing compared with control cells. Soft agar colonies of CLP-expressing cells had rough boundaries, with peripheral cells migrating away from the colony. Cells expressing CLP displayed a striking increase in the number and length of myosin-10-positive filopodia and showed increased mobility in a wound healing assay. This increase in wound healing capacity was prevented by small interference RNA-mediated down-regulation of myosin-10. Fluorescence microscopy and Western blotting revealed that CLP expression results in up-regulation of its target protein, myosin-10. This up-regulation occurs at the protein level by stabilization of myosin-10. Thus, CLP functions by increasing the stability of myosin-10, leading to enhanced myosin-10 function and a subsequent increase in filopodial dynamics and cell migration. In stratified epithelia, CLP may be required during terminal differentiation to increase myosin-10 function as cells migrate toward the upper layers and establish new adhesive contacts.

Highlights

Human calmodulin-like protein (CLP)2 was first discovered as the product of an intronless gene expressed in normal epithelial cells but strongly down-regulated in transformed cells and epithelial cancers [1,2,3]
We used the inducible T-REx system to generate stable HeLa cell clones in which CLP expression is repressed in the absence of tetracycline but can be turned on upon addition of the inducing agent
Calmodulin-like protein was first identified as a protein down-regulated in breast cancer and absent or strongly reduced in all transformed cell lines tested [2, 3, 8]

Summary

Introduction

Human calmodulin-like protein (CLP)2 was first discovered as the product of an intronless gene expressed in normal epithelial cells but strongly down-regulated in transformed cells and epithelial cancers [1,2,3]. Human calmodulin-like protein (CLP) is an epithelial-specific protein that is expressed during cell differentiation but down-regulated in primary cancers and transformed cell lines. CLP expression resulted in increased cell motility in a wound healing assay, and individual cells displayed more and longer filopodia with increased levels of Myo-10.

Results

Conclusion