Cdc37/Hsp90 protein complex disruption triggers an autophagic clearance cascade for TDP-43 protein.
The RNA-binding protein, trans-active response DNA-binding protein 43 (TDP-43), is normally found in the nucleus, but in amyotrophic lateral sclerosis, frontal temporal dementia, and some cases of Alzheimer disease it is cleaved and mislocalized to the cytosol, leading to accumulation. The mechanisms contributing to this are largely unknown. Here, we show that part of the normal clearance cascade for TDP-43 involves the Cdc37/Hsp90 complex. An Hsp90 inhibitor that disrupts the Cdc37/Hsp90 complex reduced TDP-43 levels to a greater extent than a standard Hsp90 ATPase inhibitor. When Cdc37 was depleted, TDP-43 underwent proteolytic clearance that was dependent on nuclear retrotranslocation and autophagic uptake. Accumulation of the microtubule-associated protein tau prevented the clearance of cleaved TDP-43, but not its production. This caused cleaved TDP-43 to accumulate, a feature observed in the brain of persons with Alzheimer disease. Clearance of cleaved TDP-43 was also prevented by knockdown of the autophagic inducer beclin1. Thus, in cells where TDP-43 clearance is normally needed, a system that employs manipulation of the Hsp90 complex and autophagy exists. But when tau accumulation is occurring, cleaved TDP-43 can no longer be cleared, perhaps explaining the emergence of these co-pathologies.
Department of Pharmaceutical Sciences, University of South Florida Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, Florida 33613, USA. ujinwal@health.usf.edu
Umesh K
UK
Jinwal
Jose F
JF
Abisambra
Juan
J
Zhang
Sheetal
S
Dharia
John C
JC
O'Leary
Tina
T
Patel
Kaitlyn
K
Braswell
Twisha
T
Jani
Jason E
JE
Gestwicki
Chad A
CA
Dickey
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D018833:Chaperonins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism; D016875:tau Proteins / Q000235:genetics / Q000378:metabolism
C498362:CDC37 protein, human; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D018841:HSP90 Heat-Shock Proteins; D016875:tau Proteins; D011065:Poly(ADP-ribose) Polymerases; D018833:Chaperonins