A17 Chaperone biology and huntington aggregation

Huntington’s disease is driven by protein aggregation related to the polyglutamine expansion, although the precise entities that cause toxicity are still a matter of debate. It is likely that these aggregates have dominant toxic effects through multiple, likely parallel acting and self-perpetuating mechanisms, including multi-organellar damage and a progressive decline in protein quality control. A very early event seen in many Huntington models (and well as many other aggregation diseases) is a collapse of nuclear pore complexes, resulting in defects in nucleocytoplasmic trafficking (Grima et al., Neuron 94 (2017) 93). One possible way to counteract the downstream effects of mutant huntingtin aggregation is to increase selective components of the protein quality control system in cells that can prevent the amyloidogenesis process. In a screen done some years ago, we identified that up-regulation of the Hsp70 co-chaperone DNAJB6 can powerfully suppress mutant huntington aggregation (Hageman et al., Mol Cell. 37 (2010) 355) and delay disease onset in the R6/2 huntington mouse model (Kakkar et al., Mol Cell 62 (2016)272). Our recent data now link DNAJB6 expression not only to neuronal hypersensitivity to polyglutamine aggregation, but also show that DNAJB6 is crucial for physiological maintenance of nuclear pore integrity function.