HSP90-incorporating chaperome networks as biosensor for disease-related pathways in patient-specific midbrain dopamine neurons

Abstract

Environmental and genetic risk factors contribute to Parkinson’s Disease (PD) pathogenesis and the associated midbrain dopamine (mDA) neuron loss. Here, we identify early PD pathogenic events by developing methodology that utilizes recent innovations in human pluripotent stem cells (hPSC) and chemical sensors of HSP90-incorporating chaperome networks. We show that events triggered by PD-related genetic or toxic stimuli alter the neuronal proteome, thereby altering the stress-specific chaperome networks, which produce changes detected by chemical sensors. Through this method we identify STAT3 and NF-κB signaling activation as examples of genetic stress, and phospho-tyrosine hydroxylase (TH) activation as an example of toxic stress-induced pathways in PD neurons. Importantly, pharmacological inhibition of the stress chaperome network reversed abnormal phospho-STAT3 signaling and phospho-TH-related dopamine levels and rescued PD neuron viability. The use of chemical sensors of chaperome networks on hPSC-derived lineages may present a general strategy to identify molecular events associated with neurodegenerative diseases.

Chaperome heterogeneity and its implications for cancer study and treatment

“…Why was epichaperome formation necessary under each stress? We observed that under toxic stress these epichaperomes remodeled dopamine production pathways, whereas under genetic stress they enhanced the fitness of inflammatory pathways along with other mechanisms (61). Thus, as we discussed in cancer (22), epichaperomes act by maintaining the and c, native protein separation and analysis by isoelectric focusing followed by immunoblotting with native cognate antibodies are used for minute biopsy specimens.…”

“…Recent work has shown that a significant driver of epichaperome formation is proteome imbalances (46,61). We identified one factor, MYC hyperactivation, to be partly responsible for driving the "rewiring" of the chaperome into the epichaperome in cancer (22,46,104).…”

“…This mechanism is not restricted to cancer. In the context of Parkinson's disease, we have recently reported how pathogenic protein network rewiring is driven by remodeling the interaction strength between chaperome members and the stability of such protein complexes (61).…”

“…A discussion of the formation and role of the epichaperome has been published recently (22,61), but an illustration of these concepts can be seen in a recent publication by Kishinevsky et al (61), where the effects of rotenone treatment, a toxic stress, or Parkin mutation, a genetic stress, or a combination of the JBC REVIEWS: Chaperome heterogeneity in cancer two on the chaperome were evaluated in midbrain dopaminergic neurons. Both rotenone and Parkin mutations induce mitochondrial dysfunction in neurons and are associated with Parkinson's disease (105).…”

“…The more HSP90 is incorporated into stable epichaperome networks, the higher the binding affinity of PU-H71 for HSP90, and the slower its dissociation (off-rate) from the stable epichaperome complexes (which provide the biochemical basis for the epichaperome networks) (Fig. 4) (46,61). This property of PU-H71 is the basis for the use of labeled PU-H71 to differentiate epichaperome-expressing tumors from those that are not and to measure the expression of the epichaperome.…”