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Many pathological proteins related to neurodegenerative diseases are misfolded, aggregating to form amyloid fibrils during pathogenesis. One of the pathological proteins, alpha-synuclein (α-syn), accumulates in the brains of Parkinson disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy (MSA), which are designated as synucleinopathies. Recently, structural properties of abnormal accumulated proteins are suggested to determine the disease phenotype. However, the biochemical and structural characteristics of those accumulated proteins are still poorly understood. We previously reported the sequence and seed-structure-dependent polymorphic fibrils of α-syn and the polymorphism was identified by proteinase K-resistant cores determined by mass spectrometry (MS) analysis. In this study, we applied this method to analyze α-syn aggregates of MSA and DLB. To perform MS analysis on proteinase K-resistant cores, we first performed amplification of α-syn aggregates by seeding reaction and protein misfolding cyclic amplification (PMCA) to obtain a sufficient amount of aggregates. Using SDS insoluble fraction of the disease brain, we successfully amplified enough α-syn aggregates for MS analysis. We differentiated between mouse and human α-syn aggregates by MS analysis on proteinase K-resistant cores of the aggregates before and after amplification. The results suggest that structural properties of amplified α-syn fibrils are preserved after PMCA and these methods can be applicable in the study of pathological proteins of the neurodegenerative disorders.

VAChT-Cre.Fast and VAChT-Cre.Slow mice selectively express Cre recombinase in approximately one half of postnatal somatic motor neurons. The mouse lines have been used in various studies with selective genetic modifications in adult motor neurons. In the present study, we crossed VAChT-Cre lines with a reporter line, CAG-Syp/tdTomato, in which synaptophysin-tdTomato fusion proteins are efficiently sorted to axon terminals, making it possible to label both cell bodies and axon terminals of motor neurons. In the mice, Syp/tdTomato fluorescence preferentially co-localized with osteopontin, a recently discovered motor neuron marker for slow-twitch fatigue-resistant (S) and fast-twitch fatigue-resistant (FR) types. The fluorescence did not preferentially co-localize with matrix metalloproteinase-9, a marker for fast-twitch fatigable (FF) motor neurons. In the neuromuscular junctions, Syp/tdTomato fluorescence was detected mainly in motor nerve terminals that innervate type I or IIa muscle fibers. These results suggest that the VAChT-Cre lines are Cre-drivers that have selectivity in S and FR motor neurons. In order to avoid confusion, we have changed the mouse line names from VAChT-Cre.Fast and VAChT-Cre.Slow to VAChT-Cre.Early and VAChT-Cre.Late, respectively. The mouse lines will be useful tools to study slow-type motor neurons, in relation to physiology and pathology.

The mammalian central nervous system (CNS) contains various types of neurons with different neuronal functions. In contrast to established roles of cell type-specific transcription factors on neuronal specification and maintenance, whether ubiquitous transcription factors have conserved or differential neuronal function remains uncertain. Here, we revealed that inactivation of a ubiquitous factor NF-Y in different sets of neurons resulted in cell type-specific neuropathologies and gene downregulation in mouse CNS. In striatal and cerebellar neurons, NF-Y inactivation led to ubiquitin/p62 pathologies with downregulation of an endoplasmic reticulum (ER) chaperone Grp94, as we previously observed by NF-Y deletion in cortical neurons. In contrast, NF-Y inactivation in motor neurons induced neuronal loss without obvious protein deposition. Detailed analysis clarified downregulation of another ER chaperone Grp78 in addition to Grp94 in motor neurons and knockdown of both ER chaperones in motor neurons recapitulated the pathology observed after NF-Y inactivation. Finally, additional downregulation of Grp78 in striatal neurons suppressed ubiquitin accumulation induced by NF-Y inactivation, implying that selective ER chaperone downregulation mediates different neuropathologies. Our data suggest distinct roles of NF-Y in protein homeostasis and neuronal maintenance in the CNS by differential regulation of ER chaperone expression.

Cell polarity depends on extrinsic spatial cues and intrinsic polarity proteins including PAR-aPKC proteins. In mammalian epithelial cells, cell-cell contacts provide spatial cues that activate the aPKC-PAR-3-PAR-6 complex to establish the landmark of the initial cellular asymmetry. PAR-1, a downstream target of the aPKC-PAR-3-PAR-6 complex, mediates further development of the apical and basolateral membrane domains. However, the relationships between the PAR-aPKC proteins and other extrinsic spatial cues provided by the extracellular matrix (ECM) remain unclear. Here, we show that PAR-1 colocalizes with laminin receptors and is required for the assembly of extracellular laminin on the basal surface of epithelial cells. Furthermore, PAR-1 regulates the basolateral localization of the dystroglycan (DG) complex, one of the laminin receptors essential for basement membrane formation. We also show that PAR-1 interacts with the DG complex and is required for the formation of a functional DG complex. These results reveal the presence of a novel inside-out pathway in which an intracellular polarity protein regulates the ECM organization required for epithelial cell polarity and tissue morphogenesis.

Huntington disease and its related autosomal-dominant polyglutamine (pQ) neurodegenerative diseases are characterized by intraneuronal accumulation of protein aggregates. Studies on protein aggregates have revealed the importance of the ubiquitin-proteasome system as the front line of protein quality control (PQC) machinery against aberrant proteins. Recently, we have shown that the autophagy-lysosomal system is also involved in cytoplasmic aggregate degradation, but the nucleus lacked this activity. Consequently, the nucleus relies entirely on the ubiquitin-proteasome system for PQC. According to previous studies, nuclear aggregates possess a higher cellular toxicity than do their cytoplasmic counterparts, however degradation kinetics of nuclear aggregates have been poorly understood. Here we show that nuclear ubiquitin ligases San1p and UHRF-2 each enhance nuclear pQ aggregate degradation and rescued pQ-induced cytotoxicity in cultured cells and primary neurons. Moreover, UHRF-2 is associated with nuclear inclusion bodies in vitro and in vivo. Our data suggest that UHRF-2 is an essential molecule for nuclear pQ degradation as a component of nuclear PQC machinery in mammalian cells.

The upstream transcription factors (USFs) USF1 and USF2 are ubiquitously expressed transcription factors that are characterized by a conserved basic helix-loop-helix/leucine zipper DNA-binding domain. They form homo- or heterodimers, and recognize E-box motifs to modulate gene expression. They are known to regulate diverse cellular functions, including the cell cycle, immune responses and glucose/lipid metabolism, but their roles in neuronal cells remain to be clarified. Here, we performed chromatin immunoprecipitation of USF1 from mouse brain cortex. Subsequent promoter array analysis (ChIP-chip) indicated that USF1 exclusively bound to the CACGTG E-box motifs in the proximal promoter regions. Importantly, functional annotation of the USF1-binding targets revealed an enrichment of genes related to lysosomal functions. Gene expression array analysis using a neuronal cell line subsequently revealed that knockdown of USFs de-regulated lysosomal gene expression. Altered expression was validated by quantitative RT-PCR, supporting the conclusion that USFs regulate lysosomal gene expression. Furthermore, USF knockdown slightly increased LysoTracker Red staining, implying a role for USFs in modulating lysosomal homeostasis. Together, our comprehensive genome-scale analyses identified lysosomal genes as targets of USFs in neuronal cells, suggesting a potential additional pathway of lysosomal regulation. Database The data for the gene expression array and ChIP-chip have been submitted to the Gene Expression Omnibus (GEO) under accession numbers GSE76615 and GSE76616, respectively.

p70 S6 kinase (p70 S6K) has been implicated in the regulation of cell cycle progression. However, the mechanism of its activation is not fully understood. In the present work, evidence is provided that an atypical protein kinase C (PKC) isotype, PKClambda, is indispensable, but not sufficient, for the activation of p70 S6K. Both the regulatory and kinase domains of PKClambda associate directly with p70 S6K. Overexpression of the kinase domain without kinase activity or the regulatory domain of PKClambda results in the suppression of the serum-induced activation of p70 S6K. In addition, two types of dominant-negative mutants of PKClambda, as well as a kinase-deficient mutant of p70 S6K, suppress serum-induced DNA synthesis and E2F activation. The overexpresion of the active form of PKClambda, however, fails to activate p70 S6K. These results suggest that PKClambda is a mediator in the regulation of p70 S6K activity and plays an important role in cell cycle progression.

Nuclear transcription factor-Y (NF-Y), a key regulator of cell-cycle progression, often loses its activity during differentiation into nonproliferative cells. In contrast, NF-Y is still active in mature, differentiated neurons, although its neuronal significance remains obscure. Here we show that conditional deletion of the subunit NF-YA in postmitotic mouse neurons induces progressive neurodegeneration with distinctive ubiquitin/p62 pathology; these proteins are not incorporated into filamentous inclusion but co-accumulated with insoluble membrane proteins broadly on endoplasmic reticulum (ER). The degeneration also accompanies drastic ER disorganization, that is, an aberrant increase in ribosome-free ER in the perinuclear region, without inducing ER stress response. We further perform chromatin immunoprecipitation and identify several NF-Y physiological targets including Grp94 potentially involved in ER disorganization. We propose that NF-Y is involved in a unique regulation mechanism of ER organization in mature neurons and its disruption causes previously undescribed novel neuropathology accompanying abnormal ubiquitin/p62 accumulation.

A thiosulphate-cytochrome c reductase was highly purified from Chlorobium thiosulphatophilum and its properties were studied. The enzyme catalyses reduction with Na 2 S 2 O 3 of c cytochromes, including cytochrome c -551 of the bacterium. Cytochrome c (555, C. thiosulphatophilum ) does not react directly with the enzyme at an appreciable rate but stimulates greatly the reduction by the enzyme of cytochrome c -551 with Na 2 S 2 O 3 . The reduction of c cytochromes catalysed by the enzyme is strongly inhibited by cyanide and sulphite. Cytochrome c (553, C. thiosulphatophilum ), a c -type cytochrome with covalently bound flavin, was found to catalyse reduction with sulphide of c cytochromes, including cytochrome c -555. The reaction is strongly inhibited by cyanide. Cyanide seems to combine strongly with cytochrome c -553 probably at the flavin moiety. Thus, the absorption spectrum attributable to flavin of the haemoprotein is changed on addition of cyanide, and neither the original spectrum nor the activity reappears even after the cyanide-treated cytochrome has been subjected to gel filtration with a Sephadex G-25 column or to isoelectric focusing.

The pH dependence of resonance Raman spectra were studied for ferrous and ferric cytochromes c, c2, c3, c-551, and c-555. The frequencies of the 1565 cm-1 (ferric) and 1539 cm-1 lines (ferrous) were sensitive to the replacement of the sixth ligand. The titration curve for the 1565 cm-1 line of cytochrome c was parallel with that for the 695 nm band. The pH dependence of the 1539 cm-1 line of ferrous cytochrome c3 suggested the stepwise replacement of the sixth ligand of its four hemes, although such pH dependence was not recognized for the Raman spectra of other ferrous cytochromes investigated. The relative intensities of three Raman lines at 1639, 1587, and 1561 cm-1 of ferric protoporphyrin bis-imidazole complex were changed clearly by the presence of detergents. The relative intensities of the corresponding three Raman lines of cytochromes b5 and c were close to those of the ferric porphyrin complex in the presence and absence of detergents, respectively, suggesting an appreciable difference in their heme environments. Reduced hemin in detergent solution, unexpectedly, gave the Raman spectrum of ferric low spin type.

A cytochrome c peroxidase (ferrocytochrome c :H 2 O 2 oxidoreductase, EC 1.11.1.5) was isolated and highly purified from Thiobacillus novellus , and its properties were studied. The enzyme has haem c as the prosthetic group, and shows a peak at 398 nm in the oxidized form and peaks at 415, 520 and 550 nm in the reduced form. It peroxidatically oxidizes the reduced form of cytochrome c (550, Thiobacillus novellus ) and mammalian-type cytochromes c but does not react or reacts very poorly with bacterial c -type cytochromes such as cytochrome c (551, Pseudomonas aeruginosa ), cytochrome c (552, Nitrosomonas europaea ) and cytochrome c (555, Chlorobium thiosulfatophilum ). One mole of the enzyme oxidizes peroxidatically 2450 moles of tuna ferrocytochrome c per min at pH 8.5 and at 18 °C. The peroxidase reaction catalysed by the enzyme is strongly inhibited by cyanide and azide.