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Different aggregation states of a nuclear localization signal‐tagged 25‐ kD a C‐terminal fragment of TAR RNA / DNA ‐binding protein 43 kD a
Author(s) -
Kitamura Akira,
Yuno Sachiko,
Muto Hideki,
Kinjo Masataka
Publication year - 2017
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/gtc.12495
Subject(s) - nls , nuclear localization sequence , nucleolus , biology , neurodegeneration , rna , fluorescence recovery after photobleaching , biophysics , cytoplasm , microbiology and biotechnology , biochemistry , gene , medicine , disease , pathology , membrane
The mechanism and cause of motor neuronal cell death in amyotrophic lateral sclerosis ( ALS ), a devastating neurodegenerative disorder, are unknown; gain of function of oligomers and aggregation of misfolded proteins, including carboxyl‐terminal fragments ( CTF s) of TAR RNA / DNA ‐binding protein 43 kD a ( TDP ‐43), have been proposed as important causative factors in the onset of ALS . We recently reported that a nuclear localization signal ( NLS )‐tagged 25‐ kD a CTF of TDP ‐43 ( TDP 25) could decrease the cell‐death proportion compared with that promoted by TDP 25. Here, we show oligomeric states of NLS ‐ TDP 25 and its detailed localization property using super‐resolution fluorescence microscopy, FRET , fluorescence recovery after photobleaching, and fluorescence correlation spectroscopy analysis. NLS ‐ TDP 25 efficiently formed a nucleolar cap structure via RNA binding in the presence of actinomycin D, but TDP 25 did not. Although cytoplasmic inclusion bodies including TDP 25 had a disordered and immobile structure, NLS ‐ TDP 25 in the nucleolus was ordered and dynamic. In the diffuse state, TDP 25 formed fewer oligomers and interacted with the molecular chaperone, HSP 70; however, NLS ‐ TDP 25 formed oligomers. These results suggested that NLS ‐tagged TDP 25 can change its structure to use ordered oligomeric but nontoxic state. Moreover, the structure of ordered oligomers as well as nuclear sequestration may be important in mediating cytotoxicity in ALS pathology.