Thiruvalluvan et al. show that, upon differentiation, the cellular chaperone network is rewired. This includes a downregulation of the Hsp70 co-chaperone DNAJB6. High levels of DNAJB6 keep patient-derived neuronal progenitors resistant to the formation of amyloids. The sole knockdown of DNAJB6 in progenitors induces spontaneous aggregation of endogenously expressed polyglutamine proteins. Inversely, low levels of DNAJB6 in neurons render them hypersensitive to amyloid formation, which can be restored by re-elevating DNAJB6 expression levels.