Valosin containing protein (VCP/p97) is a novel substrate for the protein tyrosine phosphatase PTPL1

Abstract

Identification of Protein Tyrosine Phosphatase (PTP) substrates is critical in understanding cellular role in normal cells as well as cancer cells. We have previously shown that reduction of PTPL1 protein levels in Ewings sarcoma (ES) inhibit cell growth and tumorigenesis. Therefore, we sought to identify novel PTPL1 substrates that may be important for tumorigenesis. In this current work, we demonstrated that mouse embryonic fibroblasts without PTPL1 catalytic activity fail to form foci when transfected with oncogenes. We proved that catalytic activity of PTPL1 is important for ES cell growth. Using a substrate-trapping mutant of PTPL1 we identified putative PTPL1 substrates by mass-spectrometry. One of these putative substrates was characterized as Valosin Containing Protein (VCP/p97). Using multiple biochemical assays we validated VCP as a novel substrate of PTPL1. We also provide evidence that tyrosine phosphorylation of VCP might be important for its midbody localization during cytokinesis. In conclusion, our work identifies VCP as a new substrate for PTPL1, which may be important in cellular transformation. Our investigation link an oncogenic transcription factor EWS-FLI1, with a key transcriptional target protein tyrosine phosphatase PTPL1, and its substrate VCP. Given our observation that PTPL1 catalytic activity is important for cell transformation, our results may also suggest that VCP regulation by PTPL1 might be important for tumorigenesis.

Genetic alterations of protein tyrosine phosphatases in human cancers

“…Dephosphorylation of VCP/p97 by PTPN13 affects its midbody localization during cytokinesis. 114 Lastly, PTPN13 is a target of viral oncoprotein, Bcr-abl and a microRNA. 115 116 117 HPV 16 E6 oncoprotein physically associates with and degrades PTPN13 in HNSCC.…”

PTPN12/PTP-PEST Regulates Phosphorylation-Dependent Ubiquitination and Stability of Focal Adhesion Substrates in Invasive Glioblastoma Cells

“…While we have characterized these signaling links in GBM cells, it is likely that tyrosine phosphorylation-mediated regulation of Vcp occurs in other cell types, and may actually be a general regulatory mechanism during cell migration. For example, a substrate-trapping screen using Ewing sarcoma cells identified Vcp as a substrate of PTPN13/PTPL1, with Y805 as the major site of dephosphorylation (38). However, the functional significance of the PTPL1-Vcp interaction was not elucidated.…”

Proteomic Analysis of Proton Beam Irradiated Human Melanoma Cells

“…VCP (Transitional endoplasmic reticulum ATPase, or p97 or Cdc48) is a substrate for protein tyrosine phosphatase (PTPL1), which is important in cellular transformations [71] . PTPL1 can have either a pro-apoptotic effect (via the death receptor, Fas) or an anti-apoptotic impact (via Proto-oncogene tyrosine-protein kinase Src, Insulin-like growth factor 1 receptor, Human Epidermal Growth Factor Receptor 2 kinases) depending on the cellular context [43] .…”