To determine if Pikfyve inhibition rescues gain-of-function processes in vivo, we measured DPR levels in C9-BAC transgenic mice 58 with or without Apilimod treatment. Although it was not previously reported 58, we observed significantly higher levels of GR+ punctae in hippocampal neurons in C9-BAC mice than controls (Fig. 6j) using a previously-validated poly(GR) antibody 11. These data are consistent with findings in another published C9-BAC mouse model 14, suggesting that poly(GR) may be a common feature of C9-BAC mice. We also detected a low level of poly(GR) in neurons from control mice (Fig. 6j), which may be derived from other repeat regions or proteins with short poly(GR) sequences. Nevertheless, GR+ punctae levels were significantly higher in C9-BAC mouse neurons than in controls (Fig. 6j). Importantly, Apilimod treatment significantly reduced the number of GR+ punctae in hippocampal neurons in C9-BAC mice after 48 hrs (Fig. 6i, j). Therefore, small molecule inhibition of Pikfyve rescues both gain- and loss-of-function disease processes induced by C9ORF72 repeat expansion in vivo.
In advanced traditional Chinese kung fu (martial arts), Neijing (Traditional Chinese: 內勁; pinyin: nèijìng) refers to the conscious control of the practitioner's qi, or "life energy", to gain advantages in combat.[1] Nèijìng is developed by using "Neigong" (Traditional Chinese: 內功; pinyin: nèigōng) (內功), or "internal exercises," as opposed to "wàigōng" (外功), "external exercises."

Live imaging of iMNs expressing a M6PR-GFP fusion protein that localizes to M6PR+ vesicles 44 confirmed that C9ORF72 patient and C9ORF72-deficient iMNs possess increased numbers of M6PR+ vesicle clusters, and that overexpression of C9ORF72 isoform A or B rescues this phenotype (Supplementary Fig. 9c-g and Supplementary Videos 5-9). Clusters did not disperse over the time course of the assay, suggesting that they are relatively stable and not in rapid flux (Supplementary Videos 5-9). In addition, M6PR+ puncta moved with a slower average speed in C9ORF72 patient and C9ORF72+/− iMNs than controls (Supplementary Fig. 9h, i). Thus, reduced C9ORF72 levels lead to fewer lysosomes in motor neurons in vitro and in vivo, and this may be due in part to altered trafficking of M6PR+ vesicles.

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.
On the other hand, the level of the Neijing force depends on the extent one can exercise over one's will power to release an inner qi energy. Within the framework of Chinese martial arts, every person is believed to possess the inborn energy of qi. Martial artists can harness the force of qi so that it is strong enough to be applied in combat. When qi is being directed by one's will, it is called Neijing.[4]
Biotinylation of plasma membrane localized glutamate receptors was performed using the Piece™ Cell Surface Protein Isolation Kit (Thermo Fisher Scientific) following the manufacturer’s instructions. Briefly, Dox-NIL iMNs were incubated with 0.25mg/ml Sulfo-NHS-SS-Biotin in cold room for 1~2 hrs with end-to-end shaking. After quenching, cells were harvested by scraping and lysed with lysis buffer from the Piece™ Cell Surface Protein Isolation Kit or the M-PER™ mammilian protein extraction buffer (Thermo Fisher Scientific). Cell lysate was incubated with High Capacity NeutrAvidin™ agorase beads (Thermo Fisher Scientific), and the bound protein was eluted in 2X SDS-PAGE sample buffer supplemented with 50mM DTT for 1 hr at room temperature with end-to-end rotation, and further analyzed by western blot.
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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