Book Description

Several pathogenic mechanisms are involved in the pathogenesis of Parkinson’s Disease (PD), a neurodegenerative disease characterized by the loss of substantial nigra (SN) dopamine (DA) neurons. Alterations in calcium (Ca2+) homeostasis, cellular proteostasis, axonal transport, mitochondrial function, and neuroinflammation are linked to PD. However, research involving inter-organelle communication and their significance as precise mechanisms underlying neuronal death in PD remain to be elucidated. Evidence showed that perturbations in the mitochondria-endoplasmic reticulum (ER) network play an important role in the pathogenesis of PD. Alterations in the mitochondria-ER interface have been reported in PARK2 knockout mice and patients harboring PARK2 mutations. Enhanced parkin levels maintain mitochondria-ER cross-talk and assure regulated Ca2+ transfer to sustain cell bioenergetics. Several familial PD-related proteins, including Parkin and PINK1, may lead to modifications in the mitochondria-ER signaling. Interestingly, mitochondria-ER tethering suppresses mitophagy and parkin/PINK1-dependent mechanism regulates the destruction of mitochondria-ER contact sites by catalyzing a rapid burst of Mfn2 phospho-ubiquitination to trigger p97-dependent disassembly of Mfn2 complexes from the outer mitochondrial membrane. Mitofusin-mediated ER stress elicited neurodegeneration in Pink1/Parkin models of PD. α-Synuclein, a presynaptic protein, can bind to the ER-mitochondria tethering protein vesicle-associated membrane protein-associated protein B (VAPB) to disrupt Ca2+ homeostasis and mitochondrial ATP production. It has been reported that ER stress and mitochondrial cell death pathways might mediate A53T mutant α-synuclein-induced toxicity. Mitochondria-ER signaling mechanism is poorly characterized in neurons and its association in neuronal pathophysiology remains uncertain. The presence of mitochondria-ER contacts in neurons, preferentially at synapses, suggests a potential role in regulating synaptic activity. Alterations in mitochondria-ER associations are expected to be potentially detrimental to neurons, especially to SN DA neurons. Compounds from an unbiased chemical screen reverse both ER-to-Golgi trafficking defects and associated mitochondrial dysfunction in different PD models. In addition, a dibenzoylmethane derivative protects DA neurons against ER stress. Thus, mitochondria-ER signaling may represent a possible upstream drug target as potential therapeutic strategy for PD. In this Research Topic, we bring together knowledge that emphasizes the importance of mitochondria-ER communication and its impact to further dissect the pathogenic mechanisms in PD.