scholarly journals Identification of a novel caspase cleavage site in huntingtin that regulates mutant huntingtin clearance

2017 ◽  
Author(s):  
D.D.O. Martin ◽  
M. E. Schmidt ◽  
Y. T. Nguyen ◽  
N. Lazic ◽  
M. R. Hayden

ABSTRACTHuntington disease (HD) is a progressive neurodegenerative disease that initially affects the striatum leading to changes in behavior and loss of motor coordination. It is caused by an expansion in the polyglutamine repeat at the N-terminus of huntingtin (HTT) that leads to aggregation of mutant HTT. The loss of wildtype function, in combination with the toxic gain of function mutation, initiates various cell death pathways. Wildtype and mutant HTT are regulated by different post-translational modifications that can positively or negatively regulate their function or toxicity. In particular, we have previously shown that caspase cleavage of mutant HTT at amino acid position aspartate 586 (D586) by caspase-6 is critical for the pathogenesis of the disease in an HD mouse model. Herein, we describe the identification of a new caspase cleavage site at position D572 that is mediated by caspase-1. Inhibition of caspase-1 also inhibits cleavage at D586 through inhibition of caspase-6. Inhibition of caspase cleavage at D572 significantly decreases mutant HTT aggregation and significantly increased the turnover of soluble mutant HTT. This suggests that caspase-1 may be a viable target to inhibit caspase cleavage of mutant HTT at both D572 and D586 to promote mutant HTT clearance.

2018 ◽  
Vol 33 (3) ◽  
pp. 3190-3197 ◽  
Author(s):  
Dale D. O. Martin ◽  
Mandi E. Schmidt ◽  
Yen T. Nguyen ◽  
Nikola Lazic ◽  
Michael R. Hayden

1997 ◽  
Vol 138 (6) ◽  
pp. 1379-1394 ◽  
Author(s):  
Carlos Caulín ◽  
Guy S. Salvesen ◽  
Robert G. Oshima

Keratins 8 (K8) and 18 (K18) are major components of intermediate filaments (IFs) of simple epithelial cells and tumors derived from such cells. Structural cell changes during apoptosis are mediated by proteases of the caspase family. During apoptosis, K18 IFs reorganize into granular structures enriched for K18 phosphorylated on serine 53. K18, but not K8, generates a proteolytic fragment during drug- and UV light–induced apoptosis; this fragment comigrates with K18 cleaved in vitro by caspase-6, -3, and -7. K18 is cleaved by caspase-6 into NH2-terminal, 26-kD and COOH-terminal, 22-kD fragments; caspase-3 and -7 additionally cleave the 22-kD fragment into a 19-kD fragment. The cleavage site common for the three caspases was the sequence VEVD/A, located in the conserved L1-2 linker region of K18. The additional site for caspases-3 and -7 that is not cleaved efficiently by caspase-6 is located in the COOH-terminal tail domain of K18. Expression of K18 with alanine instead of serine at position 53 demonstrated that cleavage during apoptosis does not require phosphorylation of serine 53. However, K18 with a glutamate instead of aspartate at position 238 was resistant to proteolysis during apoptosis. Furthermore, this cleavage site mutant appears to cause keratin filament reorganization in stably transfected clones. The identification of the L1-2 caspase cleavage site, and the conservation of the same or very similar sites in multiple other intermediate filament proteins, suggests that the processing of IFs during apoptosis may be initiated by a similar caspase cleavage.


2000 ◽  
Vol 32 ◽  
pp. 87
Author(s):  
G. Ballardini ◽  
S. Ghetti ◽  
A. Grassi ◽  
F. Lari ◽  
D. Zauli ◽  
...  

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Rachel A Battaglia ◽  
Adriana S Beltran ◽  
Samed Delic ◽  
Raluca Dumitru ◽  
Jasmine A Robinson ◽  
...  

Alexander disease (AxD) is a fatal neurodegenerative disorder caused by mutations in glial fibrillary acidic protein (GFAP), which supports the structural integrity of astrocytes. Over 70 GFAP missense mutations cause AxD, but the mechanism linking different mutations to disease-relevant phenotypes remains unknown. We used AxD patient brain tissue and induced pluripotent stem cell (iPSC)-derived astrocytes to investigate the hypothesis that AxD-causing mutations perturb key post-translational modifications (PTMs) on GFAP. Our findings reveal selective phosphorylation of GFAP-Ser13 in patients who died young, independently of the mutation they carried. AxD iPSC-astrocytes accumulated pSer13-GFAP in cytoplasmic aggregates within deep nuclear invaginations, resembling the hallmark Rosenthal fibers observed in vivo. Ser13 phosphorylation facilitated GFAP aggregation and was associated with increased GFAP proteolysis by caspase-6. Furthermore, caspase-6 was selectively expressed in young AxD patients, and correlated with the presence of cleaved GFAP. We reveal a novel PTM signature linking different GFAP mutations in infantile AxD.


2007 ◽  
Vol 153 (3) ◽  
pp. 427-434 ◽  
Author(s):  
A. S. Lipatov ◽  
H.-L. Yen ◽  
R. Salomon ◽  
H. Ozaki ◽  
E. Hoffmann ◽  
...  

2003 ◽  
Vol 372 (1) ◽  
pp. 137-143 ◽  
Author(s):  
József TÖZSÉR ◽  
Péter BAGOSSI ◽  
Gábor ZAHUCZKY ◽  
Suzanne I. SPECHT ◽  
Eva MAJEROVA ◽  
...  

Caspases are important mediators of apoptotic cell death. Several cellular protein substrates of caspases contain potential phosphorylation site(s) at the cleavage-site region, and some of these sites have been verified to be phosphorylated. Since phosphorylation may affect substantially the substrate susceptibility towards proteolysis, phosphorylated, non-phosphorylated and substituted oligopeptides representing such cleavage sites were studied as substrates of apoptotic caspases 3, 7 and 8. Peptides containing phosphorylated serine residues at P4 and P1′ positions were found to be substantially less susceptible towards proteolysis as compared with the serine-containing analogues, while phosphoserine at P3 did not have a substantial effect. P1 serine as well as P1-phosphorylated, serine-containing analogues of an oligopeptide representing the poly(ADP-ribose) polymerase cleavage site of caspase-3 were not hydrolysed by any of these enzymes, whereas the P1 aspartate-containing peptides were efficiently hydrolysed. These findings were interpreted with the aid of molecular modelling. Our results suggest that cleavage-site phosphorylation in certain positions could be disadvantageous or detrimental with respect to cleavability by caspases. Cleavage-site phosphorylation may therefore provide a regulatory mechanism to protect substrates from caspase-mediated degradation.


Sign in / Sign up

Export Citation Format

Share Document