title: Molecular interaction of TPPP with PrP antagonized the CytoPrP-induced disruption of microtubule structures and cytotoxicity.
abstract: BACKGROUND
  Tubulin polymerization promoting protein/p25 (TPPP/p25), known as a microtubule-associated protein (MAP), is a brain-specific unstructured protein with a physiological function of stabilizing cellular microtubular ultrastructures. Whether TPPP involves in the normal functions of PrP or the pathogenesis of prion disease remains unknown. Here, we proposed the data that TPPP formed molecular complex with PrP. We also investigated its influence on the aggregation of PrP and fibrillization of PrP106-126 in vitro, its antagonization against the disruption of microtubule structures and cytotoxicity of cytosolic PrP in cells, and its alternation in the brains of scrapie-infected experimental hamsters.
  
  
  RESULTS
  Using pull-down and immunoprecipitation assays, distinct molecular interaction between TPPP and PrP were identified and the segment of TPPP spanning residues 100-219 and the segment of PrP spanning residues 106-126 were mapped as the regions responsible for protein interaction. Sedimentation experiments found that TPPP increased the aggregation of full-length recombinant PrP (PrP23-231) in vitro. Transmission electron microscopy and Thioflavin T (ThT) assays showed that TPPP enhanced fibril formation of synthetic peptide PrP106-126 in vitro. Expression of TPPP in the cultured cells did not obviously change the microtubule networks observed by a tubulin-specific immunofluorescent assay and cell growth features measured by CCK8 tests, but significantly antagonized the disruption of microtubule structures and rescued the cytotoxicity caused by the accumulation of cytosolic PrP (CytoPrP). Furthermore, Western blots identified that the levels of the endogenous TPPP in the brains of scrapie-infected experimental hamsters were significantly reduced.
  
  
  CONCLUSIONS
  Those data highlight TPPP may work as a protective factor for cells against the damage effects of the accumulation of abnormal forms of PrPs, besides its function as an agent for dynamic stabilization of microtubular ultrastructures.
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China.
authors.forename: Rui-Min
authors.initials: RM
authors.lastname: Zhou
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Jing
authors.forename: Yan
authors.initials: Y
authors.lastname: Guo
authors.forename: Chen
authors.initials: C
authors.lastname: Gao
authors.forename: Bao-Yun
authors.initials: BY
authors.lastname: Zhang
authors.forename: Cao
authors.initials: C
authors.lastname: Chen
authors.forename: Qi
authors.initials: Q
authors.lastname: Shi
authors.forename: Chan
authors.initials: C
authors.lastname: Tian
authors.forename: Zhao-Yun
authors.initials: ZY
authors.lastname: Wang
authors.forename: Han-Shi
authors.initials: HS
authors.lastname: Gong
authors.forename: Jun
authors.initials: J
authors.lastname: Han
authors.forename: Bian-Li
authors.initials: BL
authors.lastname: Xu
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Dong
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000378:metabolism / Q000648:ultrastructure; D000818:Animals; D052160:Benzothiazoles; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival; D006224:Cricetinae; D003600:Cytosol / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D008647:Mesocricetus; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011328:Prions / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012608:Scrapie / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism
chemical_list: D000682:Amyloid; D052160:Benzothiazoles; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D011328:Prions; C118136:TPPP protein, human; D013844:Thiazoles; C082632:prion protein (106-126); C009462:thioflavin T