title: Molecular mechanism of T-cell protein tyrosine phosphatase (TCPTP) activation by mitoxantrone.
abstract: T-cell protein tyrosine phosphatase (TCPTP) is a ubiquitously expressed non-receptor protein tyrosine phosphatase. It is involved in the negative regulation of many cellular signaling pathways. Thus, activation of TCPTP could have important therapeutic applications in diseases such as cancer and inflammation. We have previously shown that the α-cytoplasmic tail of integrin α1β1 directly binds and activates TCPTP. In addition, we have identified in a large-scale high-throughput screen six small molecules that activate TCPTP. These small molecule activators include mitoxantrone and spermidine. In this study, we have investigated the molecular mechanism behind agonist-induced TCPTP activation. By combining several molecular modeling and biochemical techniques, we demonstrate that α1-peptide and mitoxantrone activate TCPTP via direct binding to the catalytic domain, whereas spermidine does not interact with the catalytic domain of TCPTP in vitro. Furthermore, we have identified a hydrophobic groove surrounded by negatively charged residues on the surface of TCPTP as a putative binding site for the α1-peptide and mitoxantrone. Importantly, these data have allowed us to identify a new molecule that binds to TCPTP, but interestingly cannot activate its phosphatase activity. Accordingly, we describe here mechanism of TCPTP activation by mitoxantrone, the cytoplasmic tail of α1-integrin, and a mitoxantrone-like molecule at the atomic level. These data provide invaluable insight into the development of novel TCPTP activators, and may facilitate the rational discovery of small-molecule cancer therapeutics.
authors.affiliation: Department of Biological and Environmental Science & Nanoscience Center, P.O. Box 35, FI-40014 University of Jyväskylä, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Ylilauri
authors.forename: Elina
authors.initials: E
authors.lastname: Mattila
authors.forename: Elisa M
authors.initials: EM
authors.lastname: Nurminen
authors.forename: Jarmo
authors.initials: J
authors.lastname: Käpylä
authors.forename: Sanna P
authors.initials: SP
authors.lastname: Niinivehmas
authors.forename: Juha A
authors.initials: JA
authors.lastname: Määttä
authors.forename: Ulla
authors.initials: U
authors.lastname: Pentikäinen
authors.forename: Johanna
authors.initials: J
authors.lastname: Ivaska
authors.forename: Olli T
authors.initials: OT
authors.lastname: Pentikäinen
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D030562:Databases, Protein; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D039222:Integrin alpha1beta1 / Q000737:chemistry*; D007700:Kinetics; D008942:Mitoxantrone / Q000737:chemistry*; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000737:chemistry*; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2 / Q000737:chemistry*; D015398:Signal Transduction; D054852:Small Molecule Libraries / Q000737:chemistry*; D013095:Spermidine / Q000737:chemistry*; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D000970:Antineoplastic Agents; D039222:Integrin alpha1beta1; D010455:Peptides; D054852:Small Molecule Libraries; D008942:Mitoxantrone; C516649:PTPN2 protein, human; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2; D013095:Spermidine
keywords: 45kDa isoform of TCPTP; DSF; Differential scanning fluorimetry; ITC; Integrin; Isothermal titration calorimetry; MD; Mitoxantrone; Molecular dynamics simulation; T(m); T-cell protein tyrosine phosphatase; TC37; TC45; TCPTP; constitutively active form of TCPTP (37kDa); differential scanning fluorimetry; isothermal titration calorimetry; molecular dynamics; protein melting temperature