Modulation of the Membrane Type 1 Matrix Metalloproteinase Cytoplasmic Tail Enhances Tumor Cell Invasion and Proliferation in Three-dimensional Collagen Matrices

M Sharon Stack,Yi I Wu,Yueying Liu,H.G Munshi,Natalie M Moss

doi:10.1074/jbc.m109.020362

Abstract

Increasing evidence suggests that the cytoplasmic tail of membrane type 1 matrix metalloproteinase (MT1-MMP) is subject to phosphorylation and that this modification may influence its enzymatic activity at the cell surface. In this study, phosphorylated MT1-MMP is detected using a phospho-specific antibody recognizing a protein kinase C consensus sequence (phospho-TXR), and a MT1-MMP tail peptide is phosphorylated by exogenous protein kinase C. To characterize the potential role of cytoplasmic residue Thr(567) in these processes, mutants that mimic a state of either constitutive (T567E) or defective phosphorylation (T567A) were expressed and analyzed for their functional effects on MT1-MMP activity and cellular behavior. Phospho-mimetic mutants of Thr(567) exhibit enhanced matrix invasion as well as more extensive growth within a three-dimensional type I collagen matrix. Together, these findings suggest that MT1-MMP surface action is regulated by phosphorylation at cytoplasmic tail residue Thr(567) and that this modification plays a critical role in processes that are linked to tumor progression.

Highlights

Soluble matrix metalloproteinases (MMPs), membrane type 1 matrix metalloproteinase (MT1-MMP) has a stretch of hydrophobic amino acids that traverse the cell membrane, followed by a short cytoplasmic tail composed of 20 amino acids [3]
Soluble MMPs, MT1-MMP has a stretch of hydrophobic amino acids that traverse the cell membrane, followed by a short cytoplasmic tail composed of 20 amino acids [3]
We report that MT1-MMP bears a threonine phosphorylation site in its cytoplasmic tail and that this modification plays an important role in regulating several aspects of carcinoma cell behavior, including invasion and three-dimensional growth

Summary

Introduction

Soluble MMPs, MT1-MMP has a stretch of hydrophobic amino acids that traverse the cell membrane, followed by a short cytoplasmic tail composed of 20 amino acids [3]. We report that MT1-MMP bears a threonine phosphorylation site in its cytoplasmic tail and that this modification plays an important role in regulating several aspects of carcinoma cell behavior, including invasion and three-dimensional growth.

Results

Conclusion