title: The nuclear RhoA exchange factor Net1 interacts with proteins of the Dlg family, affects their localization, and influences their tumor suppressor activity.
abstract: Net1 is a RhoA-specific guanine nucleotide exchange factor which localizes to the nucleus at steady state. A deletion in its N terminus redistributes the protein to the cytosol, where it activates RhoA and can promote transformation. Net1 contains a PDZ-binding motif at the C terminus which is essential for its transformation properties. Here, we found that Net1 interacts through its PDZ-binding motif with tumor suppressor proteins of the Dlg family, including Dlg1/SAP97, SAP102, and PSD95. The interaction between Net1 and its PDZ partners promotes the translocation of the PDZ proteins to nuclear subdomains associated with PML bodies. Interestingly, the oncogenic mutant of Net1 is unable to shuttle the PDZ proteins to the nucleus, although these proteins still associate as clusters in the cytosol. Our results suggest that the ability of oncogenic Net1 to transform cells may be in part related to its ability to sequester tumor suppressor proteins like Dlg1 in the cytosol, thereby interfering with their normal cellular function. In agreement with this, the transformation potential of oncogenic Net1 is reduced when it is coexpressed with Dlg1 or SAP102. Together, our results suggest that the interaction between Net1 and Dlg1 may contribute to the mechanism of Net1-mediated transformation.
authors.affiliation: Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, 12-026 Lineberger, CB#7295, Chapel Hill, NC 27599, USA. rafaelgm@med.unc.edu
authors.forename: Rafael
authors.initials: R
authors.lastname: García-Mata
authors.forename: Adi D
authors.initials: AD
authors.lastname: Dubash
authors.forename: Lisa
authors.initials: L
authors.lastname: Sharek
authors.forename: Heather S
authors.initials: HS
authors.lastname: Carr
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Frost
authors.forename: Keith
authors.initials: K
authors.lastname: Burridge
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D002471:Cell Transformation, Neoplastic; D003600:Cytosol / Q000378:metabolism; D000074288:Discs Large Homolog 1 Protein; D000076122:Disks Large Homolog 4 Protein; D004789:Enzyme Activation; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D019913:Nuclear Localization Signals; D015513:Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D054731:PDZ Domains; D011485:Protein Binding; D021381:Protein Transport; D051381:Rats; D000074407:SAP90-PSD95 Associated Proteins; D017384:Sequence Deletion; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D000074288:Discs Large Homolog 1 Protein; D000076122:Disks Large Homolog 4 Protein; C000614189:Dlg1 protein, mouse; C101195:Dlg3 protein, rat; C501449:Dlg4 protein, rat; D020662:Guanine Nucleotide Exchange Factors; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C099763:NET1 protein, human; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D019913:Nuclear Localization Signals; D015513:Oncogene Proteins; D000074407:SAP90-PSD95 Associated Proteins; D025521:Tumor Suppressor Proteins; D020742:rhoA GTP-Binding Protein