With the four components of a chemical heat pump (two solid-gas reactors, an evaporator and a condenser), a cycle of the double-effect type can be applied to continuous refrigeration. The performance of this process is analysed, allowing the infinite sink temperature and the couples of reactive salts to be used, which depend on the production temperature envisaged, to be selected. The results are ... [Show full abstract]Read more
Given our observation that iMNs with reduced C9ORF72 levels are hypersensitive to DPR toxicity, we wondered if this might be due to a general disruption of protein turnover by DPRsHowever, PR50-GFP expression did not impair turnover of APP or Tau (Supplementary Fig. 14f, g and Supplementary Fig. 5l). Thus the neurotoxicity caused by DPRs that accumulate rapidly in C9-ALS motor neurons due to reduced C9ORF72 levels is not due to global disruption of protein turnover.
To verify that PIKFYVE-dependent modulation of vesicle trafficking was responsible for rescuing C9ORF72 patient iMN survival, we tested the ability of a constitutively active RAB5 mutant to block C9ORF72 patient iMN degeneration. Active RAB5 recruits PI3-kinase to synthesize PI3P from PI and therefore, like PIKFYVE inhibition, increases PI3P levels 56. Constitutively active RAB5 did not improve control iMN survival (n=2 controls)(Supplementary Fig. 15k), but successfully rescued C9ORF72 patient iMN survival (n=3 patients)(Supplementary Fig. 15l). In constrast, dominant negative RAB5, wild-type RAB5, or constitutively active RAB7 did not rescue C9ORF72 patient iMN survival (n=1, 3, 3 patients, respectively)(Supplementary Fig. 14m-o).
Therapeutic strategies in development for C9ORF72 ALS/FTD target gain-of-function mechanisms. These include ASOs 6–8 and small molecules 13 that disrupt RNA foci formation. However, these approaches have not fully rescued neurodegeneration in human patient-derived neurons 6–8,13, indicating that replacing C9ORF72 function or new therapeutic targets may be required.
Yingxiao Shi,#1,2,3 Shaoyu Lin,#1,2,3 Kim A. Staats,1,2,3 Yichen Li,1,2,3 Wen-Hsuan Chang,1,2,3 Shu-Ting Hung,1,2,3 Eric Hendricks,1,2,3 Gabriel R. Linares,1,2,3 Yaoming Wang,3,4 Esther Y. Son,5 Xinmei Wen,6 Kassandra Kisler,3,4 Brent Wilkinson,3 Louise Menendez,1,2,3 Tohru Sugawara,1,2,3 Phillip Woolwine,1,2,3 Mickey Huang,1,2,3 Michael J. Cowan,1,2,3 Brandon Ge,1,2,3 Nicole Koutsodendris,1,2,3 Kaitlin P. Sandor,1,2,3 Jacob Komberg,1,2,3 Vamshidhar R. Vangoor,7 Ketharini Senthilkumar,7 Valerie Hennes,1,2,3 Carina Seah,1,2,3 Amy R. Nelson,3,4 Tze-Yuan Cheng,8 Shih-Jong J. Lee,8 Paul R. August,9 Jason A. Chen,10 Nicholas Wisniewski,10 Hanson-Smith Victor,10 T. Grant Belgard,10 Alice Zhang,10 Marcelo Coba,3,11 Chris Grunseich,12 Michael E. Ward,12 Leonard H. van den Berg,13 R. Jeroen Pasterkamp,7 Davide Trotti,6 Berislav V. Zlokovic,3,4 and Justin K. Ichida1,2,3,†
Immunostaining revealed that C9ORF72+/− and C9ORF72−/− iMNs contained elevated levels of NMDA (NR1) and AMPA (GLUR1) receptors on neurites and dendritic spines compared to control iMNs under basal conditions (Fig. 4a, c, d and Supplementary Fig. 5b and 10a, c-e, g, h, j, k). In addition, control iMNs treated with C9ORF72-specific ASOs displayed increased numbers of NMDA and AMPA receptors in their neurites (Supplementary Fig. 10l, m). C9ORF72 patient iMNs (n=3 patients) also showed elevated NR1 and GLUR1 levels compared to controls (n=3 controls), and forced expression of C9ORF72 isoform B reduced glutamate receptor levels in patient iMNs (n=3 patients) to that of controls (n=3 controls) (Fig. 4a-c and Supplementary Fig. 10a-h). mRNA levels of NR1 (GRIN1) and GLUR1 (GRIA1) were not elevated in flow-purified C9ORF72+/− iMNs, indicating that increased transcription could not explain the increased glutamate receptor levels (Supplementary Fig. 10n).
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