Rab8, POSH, and TAK1 regulate synaptic growth in a Drosophila model of frontotemporal dementia.

Ryan J H West, Yubing Lu, Bruno Marie, Fen-Biao Gao, Sean T Sweeney

The Journal of cell biology 2015 Mar 30

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Mutations in genes essential for protein homeostasis have been identified in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) patients. Why mature neurons should be particularly sensitive to such perturbations is unclear. We identified mutations in Rab8 in a genetic screen for enhancement of an FTD phenotype associated with ESCRT-III dysfunction. Examination of Rab8 mutants or motor neurons expressing a mutant ESCRT-III subunit, CHMP2B(Intron5), at the Drosophila melanogaster neuromuscular junction synapse revealed synaptic overgrowth and endosomal dysfunction. Expression of Rab8 rescued overgrowth phenotypes generated by CHMP2B(Intron5). In Rab8 mutant synapses, c-Jun N-terminal kinase (JNK)/activator protein-1 and TGF-β signaling were overactivated and acted synergistically to potentiate synaptic growth. We identify novel roles for endosomal JNK-scaffold POSH (Plenty-of-SH3s) and a JNK kinase kinase, TAK1, in regulating growth activation in Rab8 mutants. Our data uncover Rab8, POSH, and TAK1 as regulators of synaptic growth responses and point to recycling endosome as a key compartment for synaptic growth regulation during neurodegenerative processes. © 2015 West et al.

Citation

Ryan J H West, Yubing Lu, Bruno Marie, Fen-Biao Gao, Sean T Sweeney. Rab8, POSH, and TAK1 regulate synaptic growth in a Drosophila model of frontotemporal dementia. The Journal of cell biology. 2015 Mar 30;208(7):931-47