title: Distinct functional domains of PNMA5 mediate protein-protein interaction, nuclear localization, and apoptosis signaling in human cancer cells.
abstract: OBJECTIVE
  Members of paraneoplastic Ma (PNMA) family have been identified as onconeuronal antigens, which aberrant expressions in cancer cells of patients with paraneoplastic disorder (PND) are closely linked to manifestation of auto-immunity, neuro-degeneration, and cancer. The purpose of present study was to determine the role of PNMA5 and its functional relationship to MOAP-1 (PNMA4) in human cancer cells.
  
  
  METHODS
  PNMA5 mutants were generated through deletion or site-directed mutagenesis and transiently expressed in human cancer cell lines to investigate their role in apoptosis, subcellular localization, and potential interaction with MOAP-1 through apoptosis assays, fluorescence microscopy, and co-immunoprecipitation studies, respectively.
  
  
  RESULTS
  Over-expressed human PNMA5 exhibited nuclear localization pattern in both MCF-7 and HeLa cells. Deletion mapping and mutagenesis studies showed that C-terminus of PNMA5 is responsible for nuclear localization, while the amino acid residues (391KRRR) within the C-terminus of PNMA5 are required for nuclear targeting. Deletion mapping and co-immunoprecipitation studies showed that PNMA5 interacts with MOAP-1 and N-terminal domain of PNMA5 is required for interaction with MOAP-1. Furthermore, co-expression of PNMA5 and MOAP-1 in MCF-7 cells significantly enhanced chemo-sensitivity of MCF-7 to Etoposide treatment, indicating that PNMA5 and MOAP-1 interact synergistically to promote apoptotic signaling in MCF-7 cells.
  
  
  CONCLUSIONS
  Our results show that PNMA5 promotes apoptosis signaling in HeLa and MCF-7 cells and interacts synergistically with MOAP-1 through its N-terminal domain to promote apoptosis and chemo-sensitivity in human cancer cells. The C-terminal domain of PNMA5 is required for nuclear localization; however, both N-and C-terminal domains of PNMA5 appear to be required for pro-apoptotic function.
authors.affiliation: Department of Biological Sciences, Faculty of Science and Technology, Sunway University, No.5 Jalan Universiti, Bandar Sunway, 46150, Petaling Jaya, Selangor, Malaysia.
authors.forename: Yong Hoi
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Biological Sciences, Faculty of Science and Technology, Sunway University, No.5 Jalan Universiti, Bandar Sunway, 46150, Petaling Jaya, Selangor, Malaysia.
authors.forename: Siew Wai
authors.initials: SW
authors.lastname: Pang
authors.affiliation: Department of Biological Sciences, Faculty of Science and Technology, Sunway University, No.5 Jalan Universiti, Bandar Sunway, 46150, Petaling Jaya, Selangor, Malaysia.
authors.forename: Chit Laa
authors.initials: CL
authors.lastname: Poh
authors.affiliation: Department of Biological Sciences, Faculty of Science and Technology, Sunway University, No.5 Jalan Universiti, Bandar Sunway, 46150, Petaling Jaya, Selangor, Malaysia. jefft@sunway.edu.my.
authors.forename: Kuan Onn
authors.identifier: http://orcid.org/0000-0002-0947-7337
authors.initials: KO
authors.lastname: Tan
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000235:genetics; D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000235:genetics; D000951:Antigens, Neoplasm / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000737:chemistry* / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D061986:MCF-7 Cells; D016297:Mutagenesis, Site-Directed; D054730:Protein Interaction Domains and Motifs / Q000235:genetics / Q000502:physiology*; D060066:Protein Interaction Maps; D021381:Protein Transport / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000951:Antigens, Neoplasm; D051017:Apoptosis Regulatory Proteins; C428449:MOAP1 protein, human; C000614138:PNMA5 protein, human
keywords: Apoptosis; Chemo-sensitivity; Functional domains; MOAP-1; PNMA5; Paraneoplastic Antigens