The molecular chaperones DNAJB6 and Hsp70 cooperate to suppress α-synuclein aggregation

Abstract

A major hallmark of Parkinson’s disease (PD) is the presence Lewy bodies (LBs) in neuronal tissues. These are protein-rich inclusions primarily composed by the protein α-synuclein (α-syn), that are not present in healthy individuals, despite the high concentration of α-syn in neurons. This suggests the presence of natural control mechanisms that efficiently suppress α-syn aggregation. Here, we demonstrate that that CRISPR/Cas9 mediated knock out (KO) of a DNAJ protein, DNAJB6, in HEK293T cells expressing α-syn, causes a massive increase in α-syn aggregation. Upon DNAJB6 re-introduction into these DNAJB6-KO HEK293T-α-syn cells, aggregation was reduced to the level of the parental cells. We then show that the suppression of α-syn aggregation is dependent on the J-domain of DNAJB6, as the catalytically inactive protein that carries the H31Q mutation, did not suppress aggregation, when re-introduced into DNAJB6-KO cells. We further demonstrate that the suppression of α-syn aggregation is dependent on the molecular chaperone Hsp70, which is consistent with the well-known function of J-domains of transferring unfolded and misfolded proteins to Hsp70. These data identify a natural control strategy to suppress α-syn aggregation and could suggest new therapeutic approaches to prevent or treat PD and related disorders.