Dynamic targeting of microtubules by TPPP/p25 affects cell survival.
Recently we identified TPPP/p25 (tubulin polymerization promoting protein/p25) as a brain-specific unstructured protein that induced aberrant microtubule assemblies and ultrastructure in vitro and as a new marker for Parkinson's disease and other synucleopathies. In this paper the structural and functional consequences of TPPP/p25 are characterized to elucidate the relationship between the in vitro and the pathological phenomena. We show that at low expression levels EGFP-TPPP/p25 specifically colocalizes with the microtubule network of HeLa and NRK cells. We found that the colocalization was dynamic (tg=5 seconds by fluorescence recovery after photobleaching) and changed during the phases of mitosis. Time-lapse and immunofluorescence experiments revealed that high levels of EGFP-TPPP/p25 inhibited cell division and promoted cell death. At high expression levels or in the presence of proteosome inhibitor, green fusion protein accumulated around centrosomes forming an aggresome-like structure protruding into the nucleus or a filamentous cage of microtubules surrounding the nucleus. These structures showed high resistance to vinblastin. We propose that a potential function of TPPP/p25 is the stabilization of physiological microtubular ultrastructures, however, its upregulation may directly or indirectly initiate the formation of aberrant protein aggregates such as pathological inclusions.
Lehotzky
Atilla
A
Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, 1113 Budapest, Hungary.
Tirián
László
L
Tökési
Natália
N
Lénárt
Péter
P
Szabó
Bálint
B
Kovács
János
J
Ovádi
Judit
J
D000818:Animals; D016923:Cell Death; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival; D018385:Centrosome / Q000648:ultrastructure; D003599:Cytoskeleton / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008853:Microscopy; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D008870:Microtubules / Q000648:ultrastructure*; D008938:Mitosis; D009419:Nerve Tissue Proteins / Q000378:metabolism / Q000502:physiology*; D009474:Neurons / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D061988:Proteasome Inhibitors; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014747:Vinblastine / Q000494:pharmacology
D009419:Nerve Tissue Proteins; D061988:Proteasome Inhibitors; D011993:Recombinant Fusion Proteins; C118136:TPPP protein, human; D049452:Green Fluorescent Proteins; D014747:Vinblastine; D004247:DNA; D017239:Paclitaxel