Sumihiro Kawajiri

PINK1 stabilized by mitochondrial depolarization recruits Parkin to damaged mitochondria and activates latent Parkin for mitophagy

Defective mitochondrial quality control is shown to be a mechanism for neurodegeneration in some forms of Parkinsons disease.

Mechanisms of Mitochondrial Fission and Fusion

Mitochondria continually change shape through the combined actions of fission, fusion, and movement along cytoskeletal tracks. The lengths of mitochondria and the degree to which they form closed networks are determined by the balance between fission and fusion rates. These rates are influenced by metabolic and pathogenic conditions inside mitochondria and by their cellular environment. Fission and fusion are important for growth, for mitochondrial redistribution, and for maintenance of a healthy mitochondrial network. In addition, mitochondrial fission and fusion play prominent roles in disease-related processes such as apoptosis and mitophagy. Three members of the Dynamin family are key components of the fission and fusion machineries. Their functions are controlled by different sets of adaptor proteins on the surface of mitochondria and by a range of regulatory processes. Here, we review what is known about these proteins and the processes that regulate their actions.

Caffeine induces apoptosis by enhancement of autophagy via PI3K/Akt/mTOR/p70S6K inhibition

Caffeine is one of the most frequently ingested neuroactive compounds. All known mechanisms of apoptosis induced by caffeine act through cell cycle modulation or p53 induction. It is currently unknown whether caffeine-induced apoptosis is associated with other cell death mechanisms, such as autophagy. Herein we show that caffeine increases both the levels of microtubule-associated protein 1 light chain 3-II and the number of autophagosomes, through the use of western blotting, electron microscopy and immunocytochemistry techniques. Phosphorylated p70 ribosomal protein S6 kinase (Thr389), S6 ribosomal protein (Ser235/236), 4E-BP1 (Thr37/46) and Akt (Ser473) were significantly decreased by caffeine. In contrast, ERK1/2 (Thr202/204) was increased by caffeine, suggesting an inhibition of the Akt/mTOR/p70S6K pathway and activation of the ERK1/2 pathway. Although insulin treatment phosphorylated Akt (Ser473) and led to autophagy suppression, the effect of insulin treatment was completely abolished by caffeine addition. Caffeine-induced autophagy was not completely blocked by inhibition of ERK1/2 by U0126. Caffeine induced reduction of mitochondrial membrane potentials and apoptosis in a dose-dependent manner, which was further attenuated by the inhibition of autophagy with 3-methyladenine or Atg7 siRNA knockdown. Furthermore, there was a reduced number of early apoptotic cells (annexin V positive, propidium iodide negative) among autophagy-deficient mouse embryonic fibroblasts treated with caffeine than their wild-type counterparts. These results support previous studies on the use of caffeine in the treatment of human tumors and indicate a potential new target in the regulation of apoptosis.

PINK1 is recruited to mitochondria with parkin and associates with LC3 in mitophagy.

MINT‐7557173: LC3 (uniprotkb:Q9GZQ8) physically interacts (MI:0915) with PINK1 (uniprotkb:Q9BXM7) by anti bait coimmunoprecipitation (MI:0006)

Mutations in Fis1 disrupt orderly disposal of defective mitochondria

The mitochondrial fission protein Drp1 binds to Mff on mitochondria, followed by entry into a complex with Fis1 at the ER–mitochondrial interface. Mutations in Fis1 disrupt disposal of defective mitochondria when fission is induced by stress. Fis1 thus acts in sequence with Mff to couple mitochondrial fission with downstream degradation processes.

Extensive hemispheric lesions with radiological evidence of blood–brain barrier integrity in a patient with neuromyelitis optica

Anti-aquaporin-4 antibody (NMO-IgG) is used as a diagnostic marker for neuromyelitis optica (NMO). Although the mechanism of spinal cord lesions in NMO has been investigated, that of extensive hemispheric lesions with brain edema remains unclear. Here we report a 36-year-old woman with NMO positive for NMO-IgG, who developed an acute disseminating encephalomyelitis (ADEM)-like episode after Mycoplasma pneumoniae infection. Brain MRI T2-weighted images demonstrated asymmetric tumefactive hyperintense lesions in the subcortical white matter. Importantly, no lesions on T1-weighted images were enhanced after intravenous gadolinium administration on serial brain MRIs, suggesting preserved integrity of the blood-brain barrier (BBB). Likewise, the corresponding apparent diffusion coefficient maps demonstrated persistent hyperintensity changes, which represented vasogenic edema associated with glial damage and consequent neuronal loss. The findings suggest possible involvement of deficient water elimination associated with seropositivity to NMO-IgG in the induction of vasogenic edema even in the presence of intact and functional BBB.

Segmental zoster paresis of limbs: report of three cases and review of literature.

Objectives:Segmental zoster paresis is a relatively rare complication characterized by focal motor weakness, which may occur in limbs affected by herpes zoster. We demonstrate the clinical characteristics of segmental zoster paresis by reviewing the cases of 138 patients, including 3 of our patients. Case Report and Review Summary:We report 3 patients with zoster paresis of the limbs. Patients 1 and 3 showed motor weakness in the left shoulder and arm after developing a herpetic rash in the left C5–C6 dermatomes. Patient 2 showed weakness in the right thigh and groin after a right L2–L3 herpetic eruption. The electromyograms of all 3 patients showed abnormal spontaneous activity in the affected muscles. Intravenous acyclovir and corticosteroid pulse therapy were added to oral antiviral drugs for patients 1 and 2. All 3 patients recovered favorably. Our review of the literature revealed that antiviral treatment may prevent the occurrence of zoster paresis; however, there is insufficient evidence to show what treatment hastens recovery from zoster paresis. Conclusions:Segmental zoster paresis is still underrecognized by neurologists. Awareness of this disorder is important because it may eliminate unnecessary invasive investigations and lead to appropriate treatment. Further studies on the treatment are necessary.

Randomized, double-blind, placebo-controlled pilot trial of reduced coenzyme Q10 for Parkinson's disease

INTRODUCTION Mitochondrial complex I deficiencies have been found in post-mortem brains of patients with Parkinsons disease (PD). Coenzyme Q10 (CoQ10) is the electron acceptor found in complexes I and II, and is a potent antioxidant. A recent trial of the oxidized form of CoQ10 for PD failed to show benefits; however, the reduced form of CoQ10 (ubiquinol-10) has shown better neuroprotective effects in animal models. METHODS Randomized, double-blind, placebo-controlled, parallel-group pilot trials were conducted to assess the efficacy of ubiquinol-10 in Japanese patients with PD. Participants were divided into two groups: PD experiencing wearing off (Group A), and early PD, without levodopa (with or without a dopamine agonist) (Group B). Participants took 300 mg of ubiquinol-10 or placebo per day for 48 weeks (Group A) or 96 weeks (Group B). RESULTS In Group A, total Unified Parkinsons Disease Rating Scale (UPDRS) scores decreased in the ubiquinol-10 group (n = 14; mean ± SD [-4.2 ± 8.2]), indicating improvement in symptoms. There was a statistically significant difference (p < 0.05) compared with the placebo group (n = 12; 2.9 ± 8.9). In Group B, UPDRS increased in the ubiquinol-10 group (n = 14; 3.9 ± 8.0), as well as in the placebo group (n = 8; 5.1 ± 10.3). CONCLUSIONS This is the first report showing that ubiquinol-10 may significantly improve PD with wearing off, as judged by total UPDRS scores, and that ubiquinol-10 is safe and well tolerated.

Zonisamide reduces cell death in SH-SY5Y cells via an anti-apoptotic effect and by upregulating MnSOD

Zonisamide, originally known as an antiepileptic drug, has been approved in Japan as adjunctive therapy with levodopa for the treatment of Parkinsons disease (PD). Although zonisamide reduces neurotoxicity, the precise mechanism of this action is not known. Here, we show that zonisamide increases cell viability in SH-SY5Y cells via an anti-apoptotic effect and by upregulating levels of manganese superoxide dismutase (MnSOD). These results would give us novel evidences of PD treatment.

p150glued-Associated Disorders Are Caused by Activation of Intrinsic Apoptotic Pathway

Mutations in p150glued cause hereditary motor neuropathy with vocal cord paralysis (HMN7B) and Perry syndrome (PS). Here we show that both overexpression of p150glued mutants and knockdown of endogenous p150glued induce apoptosis. Overexpression of a p150glued plasmid containing either a HMN7B or PS mutation resulted in cytoplasmic p150glued-positive aggregates and was associated with cell death. Cells containing mutant p150glued aggregates underwent apoptosis that was characterized by an increase in cleaved caspase-3- or Annexin V-positive cells and was attenuated by both zVAD-fmk (a pan-caspase inhibitor) application and caspase-3 siRNA knockdown. In addition, overexpression of mutant p150glued decreased mitochondrial membrane potentials and increased levels of translocase of the mitochondrial outer membrane (Tom20) protein, indicating accumulation of damaged mitochondria. Importantly, siRNA knockdown of endogenous p150glued independently induced apoptosis via caspase-8 activation and was not associated with mitochondrial morphological changes. Simultaneous knockdown of endogenous p150glued and overexpression of mutant p150glued had additive apoptosis induction effects. These findings suggest that both p150glued gain-of-toxic-function and loss-of-physiological-function can cause apoptosis and may underlie the pathogenesis of p150glued-associated disorders.