Parkinson's disease (PD) is a common neurodegenerative disorder in the aging population, affecting more than 1% over the age of 65 years. Certain rare forms of the disease are monogenic, representing 5-10% of PD patients, but there is increasing evidence that multiple genetic risk factors are important also for common forms of PD. To date, 13 genetic loci, PARK1-13, have been suggested for rare forms of PD such as autosomal dominant and autosomal recessive PD. At six of these loci, genes have been identified and reported by several groups to carry mutations that are linked to affected family members. Genes in which mutations have been linked to familial PD have also been shown to be candidate genes for idiopathic forms of PD, as those same genes may also carry other mutations that merely increase the risk. Four of the PARK genes, SNCA at PARK1, UCH-L1 at PARK5, PINK1 at PARK6 and LRRK2 at PARK8, have been implicated in sporadic PD. There are indeed multiple genetic risk factors that combine in different ways to increase or decrease risk, and several of these need to be identified in order to begin unwinding the causative pathways leading to the different forms of PD. In this review, we present the molecular genetics of PD that are understood today, to help explain the pathways leading to neurodegeneration.

BACKGROUND

The cause and pathogenesis of Parkinson's disease remain unknown; mitochondrial dysfunction, oxidative damage, environmental factors, and genetic predisposition might all be involved. Identification of the causative genes for familial Parkinson's diseases allow study of the pathogenesis of the disease at the molecular level.

BACKGROUND

Katja Hedrich and colleagues studied 75 Serbian patients with early-onset Parkinson's disease for DJ-1 mutations (Neurology 2004; 62: 389-94). One patient was a compound heterozygote and another had a heterozygous exon deletion. DJ-1 mutations seem to be rare in this European population. By contrast, parkin mutations have been found in about 50% of familial cases and in 10-20% of cases without a positive family history.

CONCLUSIONS

The fact that parkin is a ubiquitin ligase gives special meaning to the molecular mechanism of neurodegeneration in general. In Parkinson's disease, Lewy bodies are immunoreactive for ubiquitin. Accumulation of abnormal proteins has also been seen in other neurodegenerative disorders. Disturbance of protein degradation by the ubiquitin-proteasome system might have a critical role in neurodegeneration. Although alpha-synuclein mutations are infrequent, alpha-synuclein accumulates in Lewy bodies, and alpha-synuclein fibrils impair the 26S proteasome function. UCH-L1 is also an abundant deubiquitylating enzyme, and its mutation is linked to PARK5. Furthermore, DJ-1 might interact with SUMO-1 (small ubiquitin-like modifier), which can counteract ubiquitin and stabilise proteins against degradation by the 26S proteasome. Uncovering the mechanisms of protein degradation should add importantly to understanding the neurodegenerative process in these neurodegenerative diseases.

Antisense (AS) transcripts are RNA molecules that are transcribed from the opposite strand to sense (S) genes forming S/AS pairs. The most prominent configuration is when a lncRNA is antisense to a protein coding gene. Increasing evidences prove that antisense transcription may control sense gene expression acting at distinct regulatory levels. However, its contribution to brain function and neurodegenerative diseases remains unclear. We have recently identified AS Uchl1 as an antisense to the mouse Ubiquitin carboxy-terminal hydrolase L1 (Uchl1) gene (AS Uchl1), the synthenic locus of UCHL1/PARK5. This is mutated in rare cases of early-onset familial Parkinson's Disease (PD) and loss of UCHL1 activity has been reported in many neurodegenerative diseases. Importantly, manipulation of UchL1 expression has been proposed as tool for therapeutic intervention. AS Uchl1 induces UchL1 expression by increasing its translation. It is the representative member of SINEUPs (SINEB2 sequence to UP-regulate translation), a new functional class of natural antisense lncRNAs that activate translation of their sense genes. Here we take advantage of FANTOM5 dataset to identify the transcription start sites associated to S/AS pair at Uchl1 locus. We show that AS Uchl1 expression is under the regulation of Nurr1, a major transcription factor involved in dopaminergic cells' differentiation and maintenance. Furthermore, AS Uch1 RNA levels are strongly down-regulated in neurochemical models of PD in vitro and in vivo. This work positions AS Uchl1 RNA as a component of Nurr1-dependent gene network and target of cellular stress extending our understanding on the role of antisense transcription in the brain.

Welding generates complex metal aerosols, inhalation of which is linked to adverse health effects among welders. An important health concern of welding fume (WF) exposure is neurological dysfunction akin to Parkinson's disease (PD), thought to be mediated by manganese (Mn) in the fumes. Also, there is a proposition that welding might accelerate the onset of PD. Our recent findings link the presence of Mn in the WF with dopaminergic neurotoxicity seen in rats exposed to manual metal arc-hard surfacing (MMA-HS) or gas metal arc-mild steel (GMA-MS) fumes. To elucidate the molecular mechanisms further, we investigated the association of PD-linked (Park) genes and mitochondrial function in causing dopaminergic abnormality. Repeated instillations of the two fumes at doses that mimic ∼1 to 5 yr of worker exposure resulted in selective brain accumulation of Mn. This accumulation caused impairment of mitochondrial function and loss of tyrosine hydroxylase (TH) protein, indicative of dopaminergic injury. A fascinating finding was the altered expression of Parkin (Park2), Uchl1 (Park5), and Dj1 (Park7) proteins in dopaminergic brain areas. A similar regimen of manganese chloride (MnCl(2)) also caused extensive loss of striatal TH, mitochondrial electron transport components, and Park proteins. As mutations in PARK genes have been linked to early-onset PD in humans, and because welding is implicated as a risk factor for parkinsonism, PARK genes might play a critical role in WF-mediated dopaminergic dysfunction. Whether these molecular alterations culminate in neurobehavioral and neuropathological deficits reminiscent of PD remains to be ascertained.

The rare inherited form of Parkinson's disease (PD), PARK5, is caused by a missense mutation in ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1) gene, resulting in Ile93Met substitution in its gene product (UCH-L1(Ile93Met)). PARK5 is inherited in an autosomal-dominant mode, but whether the Ile93Met mutation gives rise to a gain-of-toxic-function or loss-of-function of UCH-L1 protein remains controversial. Here, we investigated the selective vulnerabilities of dopaminergic (DA) neurons in UCH-L1-transgenic (Tg) and spontaneous UCH-L1-null gracile axonal dystrophy mice to an important PD-causing insult, abnormal accumulation of alpha-synuclein (alphaSyn). Immunohistochemistry of midbrain sections of a patient with sporadic PD showed alphaSyn- and UCH-L1-double-positive Lewy bodies in nigral DA neurons, suggesting physical and/or functional interaction between the two proteins in human PD brain. Recombinant adeno-associated viral vector-mediated over-expression of alphaSyn for 4 weeks significantly enhanced the loss of nigral DA cell bodies in UCH-L1(Ile93Met)-Tg mice, but had weak effects in age-matched UCH-L1(wild-type)-Tg mice and non-Tg littermates. In contrast, the extent of alphaSyn-induced DA cell loss in gracile axonal dystrophy mice was not significantly different from wild-type littermates at 13-weeks post-injection. Our results support the hypothesis that PARK5 is caused by a gain-of-toxic-function of UCH-L1(Ile93Met) mutant, and suggest that regulation of UCH-L1 in nigral DA cells could be a future target for treatment of PD.

Progressive loss of substantia nigra dopamine neurons (SN DA) is a hallmark of aging and of Parkinson's disease (PD). Mutations in PARK genes cause familial PD forms. Increased expression of alpha-synuclein (PARK4) is a disease-triggering event in familial PD and also observed in SN DA neurons in sporadic PD but related transcriptional changes are unknown. With optimized single-cell quantitative real-time polymerase chain reaction analysis, we compared messenger RNA and microRNA levels in SN DA neurons from sporadic PD patients and controls. Non-optimally matched donor ages and RNA integrities are common problems when analyzing human samples. We dissected the influence of distinct ages and RNA integrities of our samples by applying a specifically-optimized, linear-mixed-effects model to quantitative real-time polymerase chain reaction-data. We identified that elevated alpha-synuclein messenger RNA levels in SN DA neurons of human PD brains were positively correlated with corresponding elevated levels of mRNAs for functional compensation of progressive SN DA loss and for enhanced proteasomal (PARK5/UCHL1) and lysosomal (PARK9/ATPase13A2) function, possibly counteracting alpha-synuclein toxicity. In contrast, microRNA miR-133b levels, previously implicated in transcriptional dysregulation in PD, were not altered in SN DA neurons in PD.

OBJECTIVE

Psychotropic drugs are widely prescribed in Parkinson's disease (PD) without regard to their pathobiological effects, and these drugs affect the transcription of a large number of genes. Effects of these drugs on PD risk gene transcription were therefore surveyed.

METHODS

Results summarize a comprehensive survey of psychotropic effects on messenger ribonucleic acid (mRNA) expression evident in published data for 70 genes linked to PD risk.

RESULTS

Psychotropic drugs can meaningfully affect PD risk gene mRNA transcription, including antipsychotics (upregulate dopamine receptors D2 and D3 (DRD2, DRD3); downregulate low-density lipoprotein receptor-related protein 8 (LRP8), ubiquitin carboxyl-terminal esterase L1 (UCHL1, also known as PARK5)), haloperidol (upregulates DRD3, parkin (PRKN, also known as PARK2), DRD2; downregulates brain-derived neurotrophic factor (BDNF)), risperidone (upregulates monoamine oxidase B (MAOB), DRD2), olanzapine (upregulates transmembrane protein 163 (TMEM163), BDNF, glutathione S-transferase mu 1 (GSTM1), MAOB, DRD2, solute carrier organic anion transporter family, member 3A1 (SLCO3A1)), aripiprazole (upregulates DRD2), quetiapine, paliperidone, lurasidone, carbamazepine, and many antidepressants (upregulate BDNF), lithium and bupropion (downregulate BDNF), amitriptyline (upregulates DRD3, DRD2), imipramine (upregulates BDNF, DRD3, DRD2), desipramine (upregulates BDNF, DRD3), and fluoxetine (upregulates acid beta-glucosidase (GBA), coiled-coil domain containing 62 (CCDC62), BDNF, DRD3, UCHL1, unc-13 homolog B (UNC13B), and perhaps huntingtin interacting protein 1 related (HIP1R); downregulates microtubule-associated protein tau (MAPT), methylcrotonoyl-coenzyme A carboxylase I (MCCC1), GSTM1, 28kDa calbindin 1 (CALB1)). Fluoxetine effects on BDNF and UCHL1 in GEO Profiles were statistically robust.

CONCLUSIONS

This report provides an initial summary and framework to understand the potential impact of psychotropic drugs on PD-relevant genes. Antipsychotics and serotoninergic antidepressants may potentially attenuate PD risk, and lithium and bupropion may augment risk, through MAPT, GBA, CCDC62, HIP1R, BDNF, and DRD2 transcription, with MAPT, GBA, and CCDC62 being strongly associated with PD risk in recent meta-analyses. Limitations of these findings and a research agenda to better relate them to the nigrostriatum and PD are discussed.

Protein aggregates such as Lewy bodies have done much for the scientists in the field of neurodegenerative diseases: They have highlighted the affected cell populations and they have trapped the mutant disease protein. Instead of a good reputation, however, protein aggregates have received incriminations, because they are consistently seen at the site of crime. Reviewing the arguments, crucial evidence has become known that (a) the specific neuronal pathology precedes the appearance of protein aggregates in mouse models of disease, (b) the neurodegenerative disease in patients occurs with comparable severity when visible protein aggregates remain absent, (c) the neurotoxicity in vitro is best reproduced by oligomers, not polymers of the mutant disease protein. Is it feasible that protein aggregates are inert byproducts of the disease protein malconformation, or that they even represent beneficial cellular efforts to sequestrate the soluble toxic disease protein, together with normal or aberrant interactor proteins? Whatever the answer will be, one positive role of protein aggregates seems clear: In contrast to earlier speculations that random cytoplasmic proteins are trapped within the aggregates, scientists now believe that the composition of the Lewy body reflects the network of interactions between crucial players in disease pathogenesis, such as the PARK1, PARK2 and PARK5 protein.

Quercetin glycosides, rutin and isoquercitrin, are potent antioxidants that have been found to possess neuroprotective effect in diseases like Parkinson's and Alzheimer's disease. In the present study, we have examined the gene expression changes with rutin and isoquercitrin pretreatment on 6-hydroxydopamine (6-OHDA)-treated toxicity in rat pheochromocytoma (PC12) cells. PC12 cells were pretreated with rutin or isoquercitrin and subsequently exposed to 6-OHDA. Rutin-pretreated PC12 attenuated the Park2, Park5, Park7, Casp3, and Casp7 genes which were expressed significantly in the 6-OHDA-treated PC12 cells. Rutin upregulated the TH gene which is important in dopamine biosynthesis, but isoquercitrin pretreatment did not affect the expression of this gene. Both rutin and isoquercitrin pretreatments upregulated the ion transport and antiapoptotic genes (NSF and Opa1). The qPCR array data were further validated by qRT-PCR using four primers, Park5, Park7, Casp3, and TH. This finding suggests that changes in the expression levels of transcripts encoded by genes that participate in ubiquitin pathway and dopamine biosynthesis may be involved in Parkinson's disease.

Studies of familial forms of Parkinson's disease (PD) have identified a growing number of genes that derive from the loci given the nomenclature PARK1-PARK13 (OMIM 168600). The alpha-synuclein gene has been implicated in rare autosomal dominant PD because of either mis-sense mutations (PARK1) or gene multiplications (PARK4). Moreover, UCHL1 (PARK5), LRRK2 (PARK8) and HTRA2 (PARK13) have been identified as causative genes for autosomal dominant PD, whereas parkin (PARK2), PINK1 (PARK6), DJ-1 (PARK7) and ATP13A2 (PARK9) have been identified as causative genes for autosomal recessive PD. Neuropathological examination of the kindreds of PARK1/4 showed Lewy body pathology ranging from classic PD to diffuse Lewy body disease. The pathological findings of PARK3 are similar to those of classic PD. In contrast, autopsies of patients with PARK2 showed nigral cell loss without Lewy bodies, although exceptions have been reported. Several kindreds of PARK8 included cases with Lewy body pathology, tau pathology, or with nigral cell loss in the absence of obvious protein deposition. Ubiquitin-positive inclusions that are negative for alpha-synuclein and tau are also seen in some cases. Moreover, widespread Lewy body pathology was also reported in several cases of familial Alzheimer's disease with presenilin-1 mutations.

BACKGROUND

Several genetic errors in alpha-synuclein (Park1) and ubiquitin carboxyl-terminal-hydrolase L1(Park5) genes cause autosomal dominant familial Parkinson disease. Mutations in the parkin gene (Park2) are the major cause of autosomal recessive Parkinson disease.

OBJECTIVE

To analyze the clinical and molecular data of 19 Spanish kindreds (13 with recessive, 4 with dominant, and 2 with uncertain inheritance) who have familial Parkinson disease.

METHODS

We searched for the previously described mutations in Park1 and Park5 genes and for new or described mutations in Park2. We used single-strand conformation polymorphism, direct sequencing, and restriction digestion of polymerase chain reaction (PCR)-amplified genomic DNA for this study.

RESULTS

None of these families have either Park1 or Park5 mutations. We found 5 different mutations in Park2 gene in 5 of the families with recessive inheritance. To our knowledge, 2 of these mutations, V56E and C212Y, have not been previously reported. The other mutations found (deletion of exons 3 and 5 and 225delA) have been described in other ethnic groups. Heterozygous carriers of a single Park2 mutation either were asymptomatic or developed clinical symptoms in late adulthood or after brief exposure to haloperidol therapy.

CONCLUSIONS

Mutations in Park2 gene account for 38% of the families with recessive parkinsonism in Spain. We found 2 cases of simple heterozygous Park2 mutation carriers that developed clinical symptoms, either in late adulthood or after brief exposure to parkinsonizing agents. Thus, hereditary Parkinson disease has more variable clinical phenotype and molecular defects than previously thought since heterozygous mutations could be a risk factor for parkinsonism.

BACKGROUND

Chromodomain helicase/ATPase DNA-binding protein 1-like gene (CHD1L), also known as ALC1 (amplified in liver cancer 1 gene), is a new oncogene amplified in many solid tumors. Whether this gene plays a role in invasion and metastasis of breast cancer is unknown.

METHODS

Immunohistochemistry was performed to detect the expression of CHD1L in patients with invasive ductal carcinoma and normal mammary glands. Chemotaxis, wound healing, and Transwell invasion assays were also performed to examine cell migration and invasion. Western blot analysis was conducted to detect the expression of CHD1L, MMP-2, MMP-9, pAkt/Akt, pARK5/ARK5, and pmTOR/mTOR. Moreover, ELISA was carried out to detect the expression levels of MMP-2 and MMP-9. Nude mice xenograft model was used to detect the invasion and metastasis of breast cancer cell lines.

RESULTS

CHD1L overexpression was observed in 112 of 268 patients (41.8%). This overexpression was associated with lymph node metastasis (P = 0.008), tumor differentiation (P = 0.020), distant metastasis (P = 0.026), MMP-2 (P = 0.035), and MMP-9 expression (P = 0.022). In the cell experiment, reduction of CHD1L inhibited the invasion and metastasis of breast cancer cells by mediating MMP-2 and MMP-9 expression. CHD1L knockdown via siRNA suppressed EGF-induced pAkt, pARK5, and pmTOR. This knockdown inhibited the metastasis of breast cancer cells into the lungs of SCID mice.

CONCLUSIONS

CHD1L promoted the invasion and metastasis of breast cancer cells via the PI3K/Akt/ARK5/mTOR/MMP signaling pathway. This study identified CHD1L as a potential anti-metastasis target for therapeutic intervention in breast cancer.

BACKGROUND

The purpose of this study is to detect the Parkinson's disease gene family mRNA relative expression in the non-small-cell lung cancer (NSCLC) tumor tissue and analyze the association between tumor characteristics and the Parkinson's disease gene family.

METHODS

Tumor tissue and tumor-adjacent tissue of 114 NSCLC patients were collected and SYBR quantitative analysis was used to detect the relative expression level of nine Parkinson's disease gene mRNAs. Then, paired sample test, two-sided Student's t-test, or two-sided Wilcoxon rank sum test was performed to analyze the mRNA relative expression level of nine Parkinson's disease gene mRNAs in different gender, tumor histology, and tumor stage.

RESULTS

Overexpression in the tumors was detected in 46/114 (40.35%) PARK1/4, 74/114 (64.91%) PARK2, 104/114 (91.23%) PARK5, 95/114 (83.33%) PARK6, 80/114 (70.18%) PARK7, 55/114 (48.25%) PARK8, 100/114 (87.72%) PARK9, 55/114 (48.25%) PARK15, and 99/114 (86.84%) glucocerebrosidase (GBA). Five genes PARK5 (91.23%), PARK6 (83.33%), PARK7 (70.18%), PARK9 (87.72%), and GBA (86.84%) were supposed to be overexpressed in the lung tumor tissues compared with tumor-adjacent tissues. There was no significant difference in PARK1/4, PARK2, PARK5, PARK9, and GBA mRNA expression by different tumor stage, whereas, PARK6, PARK7, PARK8, and PARK15 mRNA expression were found to have significant difference in the comparison of different tumor stages. The expression of PARK6 (P=0.01, P=0.03) and PARK15 (P<0.001, P<0.001) were significantly higher in stages I and II when compared with stage III, respectively. NSCLC patients in stage I showed the higher expression PARK7 compared to the patients in stage II (P=0.003).

CONCLUSIONS

The high expression of PARK6, PARK7, and PARK15 might lead to the occurrence of a primary NSCLC tumor, and the tumor with a decreasing expression of these three genes tends to be stages II and III. The results of our study indicate that the Parkinson's disease gene family may be a potential marker for the prediction of NSCLC.

Transgenic Atropa belladonna conferred with a herbicide-resistant trait was obtained by transformation with an Ri plasmid binary vector and plant regeneration from hairy roots. We made a chimeric construct, pARK5, containing the bar gene encoding phosphinothricin acetyltransferase flanked with the promoter for cauliflower mosaic virus 35S RNA and the 3' end of the nos gene. Leaf discs of A. belladonna were infected with Agrobacterium rhizogenes harboring an Ri plasmid, pRi15834, and pARK5. Transformed hairy roots resistant to bialaphos (5 mg/l) were selected and plantlets were regenerated. The integration of T-DNAs from pRi15834 and pARK5 were confirmed by DNA-blot hybridization. Expression of the bar gene in transformed R0 tissues and in backcrossed F1 progeny with a nontransformant and self-fertilized progeny was indicated by enzymatic activity of the acetyltransferase. The transgenic plants showed resistance towards bialaphos and phosphinothricin. Tropane alkaloids of normal amounts were produced in the transformed regenerants. These results present a successful application of transformation with an Ri plasmid binary vector for conferring an agronomically useful trait to medicinal plants.

Many reagents have emerged to study the function of specific enzymes in vitro. On the other hand, target specific reagents are scarce or need improvement allowing investigations of the function of individual enzymes in their native cellular context. We here report the development of a target-selective fluorescent small-molecule activity-based DUB probe that is active in live cells and an in vivo animal model. The probe labels active Ubiquitin Carboxy-terminal Hydrolase L1 (UCHL1), also known as neuron-specific protein PGP9.5 (PGP9.5) and parkinson disease 5 (PARK5), a DUB active in neurons that constitutes 1-2% of total brain protein. UCHL1 variants have been linked with the neurodegenerative disorders Parkinson's and Alzheimer's disease. In addition, high levels of UCHL1 also correlate often with cancer and especially metastasis. The function of UCHL1 activity or its role in cancer and neurodegenerative disease is poorly understood and few UCHL1-specific activity tools exist. We show that the reagents reported here are specific for UCHL1 over all other DUBs detectable by competitive activity-based protein profiling and by mass spectrometry. Our cell penetrable probe, which contains a cyanimide reactive moiety, binds to the active-site cysteine residue of UCHL1 in an activity-dependent manner. Its use is demonstrated by fluorescently labelling of active UCHL1 both in vitro and in live cells. We furthermore show that this probe can selectively and spatiotemporally report UCHL1 activity during the development of zebrafish embryos. Our results indicate that our probe has potential application as diagnostic tool for diseases with perturbed UCHL1 activity.

To date 11 forms of familial Parkinson's disease (PD) have been mapped to different chromosome loci, of which 6 genes have been identified as the causative genes, i.e., alpha-synuclein (SNCA), parkin, UCH-L1, PINK1, DJ-1, and LRRK2. For UCH-L1, additional families with this mutation are necessary before concluding that UCH-L1 is the definite causative gene for PARK5, as only one family so far has been reported. SNCA, UCH-L1, and LRRK2 mutations cause autosomal dominant PD and the remaining gene mutations autosomal recessive PD. Age of onset tends to be younger in familial PD compared with sporadic PD, particularly so in autosomal recessive PD. Generally familial cases respond to levodopa quite nicely and progression of the disease tends to be slower. It is an interesting question how familial PD-causing proteins are mutually related each other. In this article, we review recent progress in genetics and molecular biology of familial PD.

Rare neurological diseases shed light onto universal neurobiological processes. However, molecular mechanisms connecting genetic defects to their disease phenotypes are elusive. Here, we obtain mechanistic information by comparing proteomes of cells from individuals with rare disorders with proteomes from their disease-free consanguineous relatives. We use triple-SILAC mass spectrometry to quantify proteomes from human pedigrees affected by mutations in ATP7A, which cause Menkes disease, a rare neurodegenerative and neurodevelopmental disorder stemming from systemic copper depletion. We identified 214 proteins whose expression was altered in ATP7A-/y fibroblasts. Bioinformatic analysis of ATP7A-mutant proteomes identified known phenotypes and processes affected in rare genetic diseases causing copper dyshomeostasis, including altered mitochondrial function. We found connections between copper dyshomeostasis and the UCHL1/PARK5 pathway of Parkinson disease, which we validated with mitochondrial respiration and Drosophila genetics assays. We propose that our genealogical "omics" strategy can be broadly applied to identify mechanisms linking a genomic locus to its phenotypes.

Background: All cells accumulate insoluble protein aggregates throughout their lifespan. While many studies have characterized the canonical disease-associated protein aggregates, such as those associated with amyloid plaques, additional, undefined proteins aggregate in the brain and may be directly associated with disease and lifespan.

Methods: A proteomics approach was used to identify a large subset of insoluble proteins in the mild cognitively impaired (MCI) and Alzheimer's disease (AD) human brain. Cortical samples from control, MCI, and AD patients were separated into detergent-soluble and detergent-insoluble fractions, and high-resolution LC/MS/MS technology was used to determine which proteins became more insoluble in the disease state. Bioinformatics analyses were used to determine if the alteration of protein aggregation between AD and control patients was associated with any specific biological process. Western blots were used to validate the proteomics data and to assess the levels of secondary protein modifications in MCI and AD.

Results: There was a stage-dependent increase in detergent-insoluble proteins, with more extreme changes occurring in the AD cohort. Glycolysis was the most significantly overrepresented gene ontology biological process associated with the alteration of protein aggregation between AD and control patients. It was further shown that many low molecular weight proteins that were enriched in the AD brain were also highly aggregated, migrating on SDS-PAGE far above their predicted molecular masses. Glucose-6-phosphate isomerase, ubiquitin carboxyl-terminal hydrolase isoenzyme L1 (UCHL1/PARK5), and the DNA damage repair enzyme KU70 were among the top insoluble proteins identified by proteomics and validated by Western blot to be increased in the insoluble fractions of both MCI and AD brain samples.

Conclusions: Diverse proteins became more detergent-insoluble in the brains of both MCI and AD patients compared to age-matched controls, suggesting that multiple proteins aggregate in these diseases, likely posing a direct toxic insult to neurons. Furthermore, detergent-insoluble proteins included those with important biological activities for critical cellular processes such as energetics, proteolysis, and DNA damage repair. Thus, reduced protein solubility likely promotes aggregation and limits functionality, reducing the efficiency of multiple aspects of cell physiology. Pharmaceutical interventions that increase autophagy may provide a useful therapeutic treatment to combat protein aggregation.

Keywords: Bioinformatics; Dementia; Insoluble protein; Proteomics; Secondary modifications.

The role of ubiquitin carboxyl-terminal hydrolase L1 (UCHL1; also called PARK5) in the pathogenesis of Parkinson's disease (PD) has been controversial. Here, we find that the loss of UCHL1 destabilizes pyruvate kinase (PKM) and mitigates the PD-related phenotypes induced by PTEN-induced kinase 1 (PINK1) or Parkin loss-of-function mutations in Drosophila and mammalian cells. In UCHL1 knockout cells, cellular pyruvate production and ATP levels are diminished, and the activity of AMP-activated protein kinase (AMPK) is highly induced. Consequently, the activated AMPK promotes the mitophagy mediated by Unc-51-like kinase 1 (ULK1) and FUN14 domain-containing 1 (FUNDC1), which underlies the effects of UCHL1 deficiency in rescuing PD-related defects. Furthermore, we identify tripartite motif-containing 63 (TRIM63) as a previously unknown E3 ligase of PKM and demonstrate its antagonistic interaction with UCHL1 to regulate PD-related pathologies. These results suggest that UCHL1 is an integrative factor for connecting glycolysis and PD pathology.

A genetic contribution to the etiology of Parkinson's disease was first suspected by Charcot and later confirmed by case control, family, and twin studies, as well as by the description of large parkinsonian families with Mendelian inheritance of the disease. Recent progress in the field of molecular neurogenetics has led to the identification of several Parkinson disease genes and gene loci. Mutations in the alpha-Synuclein gene (PARK1) and in the gene for the ubiquitin C-terminal hydrolase I (PARK5), along with two gene loci harboring currently unknown genes (PARK3 and PARK4), have been linked to very rare autosomal dominantly inherited parkinsonian syndromes. Mutations in the parkins gene (PARK2), causing autosomal recessive early-onset parkinsonism, are much more common and therefore of clinical relevance. A second gene locus for an autosomal dominantly inherited Parkinsonian syndrome was recently localized on chromosome 1 (PARK6). All three parkinson genes identified thus far imply the involvement of the ubiquitin pathway of protein degradation in the pathogenesis of Parkinson's disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder of the central nervous system, affecting 1 in 50 people over the age of 60 years. PD is the result of loss of a majority of dopamine (DA) neurons in the midbrain substantia nigra. The basic pathological feature of PD is the formation of intracytoplasmic eosinophilic inclusion bodies, Lewy bodies. So far, what leads to DA neuron degeneration is uncertain. Thirteen familial PD related loci have been identified, including six mutations:α-SYN(PARK1/4), Parkin(PARK2), UCHL1(PARK5), PINK1(PARK6), DJ-1(PARK7) and LRRK2 (PARK8). Drosophila has been widely used in the study of human diseases because of its genetic advantages. The Drosophila DA synthesis is similar to human, and Drosophila DA system is also involved in motion control, so it is generally considered that DA neuron death of Drosophila can be a perfect model of PD. In this article we review the progress of research methods based on Drosophila model in study of mechanisms related to Parkinson's disease.

Clinical symptoms correlate with underlying neurodegenerative changes in the vast majority of people. However, an intriguing group of individuals demonstrate neuropathologic changes consistent with Alzheimer disease (AD) yet remain cognitively normal (termed "resilient"). Previous studies have reported less overall neuronal loss, less gliosis, and fewer comorbidities in these individuals. Herein, NanoString GeoMx™ Digital Spatial Profiler (DSP) technology was utilized to investigate protein expression differences comparing individuals with dementia and AD neuropathologic change to resilient individuals. DSP allows for spatial analysis of protein expression in multiple regions of interest (ROIs) on formalin-fixed paraffin-embedded sections. ROIs in this analysis were hippocampal neurofibrillary tangle (NFT)-bearing neurons, non-NFT-bearing neurons, and their immediate neuronal microenvironments. Analyses of 86 proteins associated with CNS cell-typing or known neurodegenerative changes in 168 ROIs from 14 individuals identified 11 proteins displaying differential expression in NFT-bearing neurons of the resilient when compared to the demented (including APP, IDH1, CD68, GFAP, SYP and Histone H3). In addition, IDH1, CD68, and SYP were differentially expressed in the environment of NFT-bearing neurons when comparing resilient to demented. IDH1 (which is upregulated under energetic and oxidative stress) and PINK1 (which is upregulated in response to mitochondrial dysfunction and oxidative stress) both displayed lower expression in the environment of NFT-bearing neurons in the resilient. Therefore, the resilient display less evidence of energetic and oxidative stress. Synaptophysin (SYP) was increased in the resilient, which likely indicates better maintenance of synapses and synaptic connections. Furthermore, neurofilament light chain (NEFL) and ubiquitin c-terminal hydrolase (Park5) were higher in the resilient in the environment of NFTs. These differences all suggest healthier intact axons, dendrites and synapses in the resilient. In conclusion, resilient individuals display protein expression patterns suggestive of an environment containing less energetic and oxidative stress, which in turn results in maintenance of neurons and their synaptic connections.

Keywords: Alzheimer disease; Digital spatial profiling (DSP); Hippocampus; Neurofibrillary tangles; Resilient; Senescence.