Yoko Imamichi

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.

Clinicogenetic study of mutations in LRRK2 exon 41 in Parkinson's disease patients from 18 countries

We screened LRRK2 mutations in exon 41 in 904 parkin‐negative Parkinsons disease (PD) patients (868 probands) from 18 countries across 5 continents. We found three heterozygous missense (novel I2012T, G2019S, and I2020T) mutations in LRRK2 exon 41. We identified 11 (1.3%) among 868 PD probands, including 2 sporadic cases and 8 (6.2%) of 130 autosomal dominant PD families. The LRRK2 mutations in exon 41 exhibited relatively common and worldwide distribution. Among the three mutations in exon 41, it has been reported that Caucasian patients with G2019S mutation have a single‐founder effect. In the present study, Japanese patients with G2019S were unlikely to have a single founder from the Caucasian patients. In contrast, I2020T mutation has a single‐founder effect in Japanese patients. Clinically, patients with LRRK2 mutations had typical idiopathic PD. Notably, several patients developed dementia and psychosis, and one with I2020T had low cardiac 123I‐metaiodobenzylguanidine (MIBG) heart/mediastinum ratio, although the ratio was not low in other patients with I2020T or G2019S. Clinical phenotypes including psychosis, dementia, and MIBG ratios are also heterogeneous, similar to neuropathology, in PD associated with LRRK2 mutations.

Mutation Analysis of the PINK1 Gene in 391 Patients With Parkinson Disease

OBJECTIVES To determine the frequency, distribution, and clinical features of Parkinson disease (PD) with PINK1 mutations. DESIGN Retrospective clinical and genetic review. SETTING University hospital. PATIENTS We performed extensive mutation analyses of PINK1 in 414 PD patients negative for parkin mutations (mean [SD] age at onset, 42.8 [14.3] years), including 391 unrelated patients (190 patients with sporadic PD and 201 probands of patients with familial PD) from 13 countries. RESULTS We found 10 patients with PD from 9 families with PINK1 mutations and identified 7 novel mutations (2 homozygous mutations [p.D297MfsX22 and p.W437R] and 5 single heterozygous mutations [p.A78V, p.P196QfsX25, p.M342V, p.W437R, and p.N542S]). No compound heterozygous mutations were found. The frequency of homozygous mutations was 4.26% (2 of 47) in families with autosomal recessive PD and 0.53% (1 of 190) in patients with sporadic PD. The frequency of heterozygous mutations was 1.89% (2 of 106) in families with potential autosomal dominant PD and 1.05% (2 of 190) in patients with sporadic PD. The mean (SD) age at onset in patients with single heterozygous mutations (53.6 [11.1] years; range, 39-69 years) was higher than that in patients with homozygous mutations (34.0 [20.3] years; range, 10-55 years). Myocardial iodine-123 metaiodobenzylguanidine uptake was low in patients with heterozygous mutations but not in those with homozygous mutations. CONCLUSIONS Our results suggest that homozygous PINK1 mutations tend to be diagnosed as the early-onset autosomal recessive form of PD. Single heterozygous mutations may contribute to the development of sporadic PD and also could be an additional genetic predisposition for developing familial PD. The reduced myocardial iodine-123 metaiodobenzylguanidine uptake observed in patients with single heterozygous PINK1 mutations is similar to that seen in patients with sporadic PD.

Screening PARK genes for mutations in early-onset Parkinson's disease patients from Queensland, Australia

A family history of Parkinsons disease (PD) is the most commonly reported risk factor after age, suggesting a genetic component to the disease in a sub-group of patients. Mutations in at least six genes have been identified that can lead to monogenic forms of PD. We screened a sample of 74 early-onset PD cases out of a cohort of 950 patients (onset <50 years) for genetic abnormalities in known familial Parkinsonism genes. A self-reported family history of PD existed for 30 patients (40.5%). Of these, 13 each had a first- or a second-degree relative with PD and four reported a more distant relative with PD. The entire coding region of the PRKN (MIM 602544), DJ-1 (MIM 602533) and PINK1 (MIM 698309) genes, and exon 41 of the LRRK2 gene (MIM 609007) were screened by direct sequencing. All exons of PRKN were examined for gene-dosage abnormalities. Screening identified five patients with putative genetic disease: two patients carried PRKN mutations (p.G12R heterozygous and p.G430D homozygous), one patient carried a p.G411S heterozygous amino acid change in the PINK1 gene and two individuals were heterozygous for the common p.G2019S mutation in LRRK2. No alpha-synuclein or DJ-1 variants were observed. Our data suggest that approximately 7% of early-onset PD cases seen in Queensland movement disorders clinics have mutations involving known PARK genes.

Familial Parkinsonism with digenic parkin and PINK1 mutations

To clarify the genetic correlation between parkin and PINK1, we screened for PINK1 mutations in 175 parkinsonism patients with parkin mutations. We detected two sibling pairs and one sporadic patient carrying both parkin and PINK1 mutations. The age at onset of Parkinsonism of patients with the digenic mutations was lower than that of patients with the same parkin mutation alone. In addition, two of three patients carrying both parkin and PINK1 mutations had schizophrenia. These findings indicate that PINK1 mutation might modify parkin mutation‐positive Parkinsonism, and PINK1 mutations might be associated withpsychiatric disorders.

Mutation analyses in amyotrophic lateral sclerosis/parkinsonism-dementia complex of the Kii peninsula, Japan.

To clarify the genetic background of amyotrophic lateral sclerosis (ALS)/parkinsonism–dementia complex (PDC) of the Kii peninsula, Japan (Kii ALS/PDC), we performed extended mutation analyses of three patients with pathologically diagnosed Kii ALS/PDC. Direct sequencing analyses were performed in 19 genes, including ALS/frontotemporal lobar degeneration (FTLD)‐related genes (SOD2, SOD3, ALS2/alsin, SMN1, PGRN, ANG, VEGF, VCP, VAPB, DCTN1, CHMP2B, and TARDBP or TDP‐43), tauopathy‐related gene (GSK3β), and parkinsonism‐related genes (alpha‐synuclein, LRRK2, parkin, DJ‐1, PINK1, and ATP13A2). Gene dosage analyses were conducted in screening of MAPT, alpha‐synuclein, TDP‐43 (or TARDBP), GSK3β, and parkin. We found no mutation in the 19 genes. We found a homozygous nonsynonymous SNP (ALS2/alsin V368M) shared by all the three patients. Gene dosage was normal in MAPT, alpha‐synuclein, TDP‐43, GSK3β, and parkin. The present findings, together with a previous negative study on MAPT and SOD1 mutation, further elucidated the lack of causative mutations in all exons, exon–intron boundaries, or some rearrangements of the reported major causative or susceptible genes related to ALS, FTLD, parkinsonism, synucleinopathy, TDP‐43 proteinopathy, and tauopathy. However, the familial aggregation and lack of any environment factors suggest that Kii ALS/PDC is caused by other yet unidentified genetic factors.

Pseudo-autosomal dominant inheritance of PARK2: two families with parkin gene mutations.

We report two families (Family S and Family N) with early-onset parkinsonism in two generations. The mode of inheritance appeared to be autosomal dominant, however, haplotye analysis suggested linkage to chromosome 6q25.2-27, the PARK2 locus, and all affected members were homozygotes in their haplotypes. In Family S, the affected father was married to unaffected mother, who carried one disease-linked haplotype at chromosome 6q25.2-27. In Family N, the unaffected mother carried one disease-linked haplotype. Quantitative PCR amplification analysis revealed exon 3 deletion in Family S and exon 5 deletion in Family N. The age of onset was from 18 to 22 years in Family S and 25 to 42 years in Family N. In both of their hometowns, most people lived in the same districts for many generations and consanguineous marriages had been common. Thus, the carrier state of the parkin gene might have been high in those communities, and marriage of a patient and a carrier is expected to result in autosomal dominant like inheritance. We conclude that PARK2 cannot be excluded even if the mode of inheritance appears as autosomal dominant, when the affected patients are young.

Decreased long-chain acylcarnitines from insufficient β-oxidation as potential early diagnostic markers for Parkinson’s disease

Increasing evidence shows that metabolic abnormalities in body fluids are distinguishing features of the pathophysiology of Parkinson’s disease. However, a non-invasive approach has not been established in the earliest or pre-symptomatic phases. Here, we report comprehensive double-cohort analyses of the metabolome using capillary electrophoresis/liquid chromatography mass-spectrometry. The plasma analyses identified 18 Parkinson’s disease-specific metabolites and revealed decreased levels of seven long-chain acylcarnitines in two Parkinson’s disease cohorts (n = 109, 145) compared with controls (n = 32, 45), respectively. Furthermore, statistically significant decreases in five long-chain acylcarnitines were detected in Hoehn and Yahr stage I. Likewise, decreased levels of acylcarnitine(16:0), a decreased ratio of acylcarnitine(16:0) to fatty acid(16:0), and an increased index of carnitine palmitoyltransferase 1 were identified in Hoehn and Yahr stage I of both cohorts, suggesting of initial β-oxidation suppression. Receiver operating characteristic curves produced using 12–14 long-chain acylcarnitines provided a large area of under the curve, high specificity and moderate sensitivity for diagnosing Parkinson’s disease. Our data demonstrate that a primary decrement of mitochondrial β-oxidation and that 12–14 long-chain acylcarnitines decreases would be promising diagnostic biomarkers for Parkinson’s disease.

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.

Serum caffeine and metabolites are reliable biomarkers of early Parkinson disease

Objective To investigate the kinetics and metabolism of caffeine in serum from patients with Parkinson disease (PD) and controls using liquid chromatography–mass spectrometry. Methods Levels of caffeine and its 11 metabolites in serum from 108 patients with PD and 31 age-matched healthy controls were examined by liquid chromatography–mass spectrometry. Mutations in caffeine-associated genes were screened by direct sequencing. Results Serum levels of caffeine and 9 of its downstream metabolites were significantly decreased even in patients with early PD, unrelated to total caffeine intake or disease severity. No significant genetic variations in CYP1A2 or CYP2E1, encoding cytochrome P450 enzymes primarily involved in metabolizing caffeine in humans, were detected compared with controls. Likewise, caffeine concentrations in patients with PD with motor complications were significantly decreased compared with those without motor complications. No associations between disease severity and single nucleotide variants of the ADORA2A gene encoding adenosine 2A receptor were detected, implying a dissociation of receptor sensitivity changes and phenotype. The profile of serum caffeine and metabolite levels was identified as a potential diagnostic biomarker by receiver operating characteristic curve analysis. Conclusion Absolute lower levels of caffeine and caffeine metabolite profiles are promising diagnostic biomarkers for early PD. This is consistent with the neuroprotective effect of caffeine previously revealed by epidemiologic and experimental studies. Classification of evidence This study provides Class III evidence that decreased serum levels of caffeine and its metabolites identify patients with PD.