title: Altered machinery of protein synthesis is region- and stage-dependent and is associated with α-synuclein oligomers in Parkinson's disease.
abstract: BACKGROUND
  Parkinson's disease (PD) is characterized by the accumulation of abnormal α-synuclein in selected regions of the brain following a gradient of severity with disease progression. Whether this is accompanied by globally altered protein synthesis is poorly documented. The present study was carried out in PD stages 1-6 of Braak and middle-aged (MA) individuals without alterations in brain in the substantia nigra, frontal cortex area 8, angular gyrus, precuneus and putamen.
  
  
  RESULTS
  Reduced mRNA expression of nucleolar proteins nucleolin (NCL), nucleophosmin (NPM1), nucleoplasmin 3 (NPM3) and upstream binding transcription factor (UBF), decreased NPM1 but not NPM3 nucleolar protein immunostaining in remaining neurons; diminished 18S rRNA, 28S rRNA; reduced expression of several mRNAs encoding ribosomal protein (RP) subunits; and altered protein levels of initiation factor eIF3 and elongation factor eEF2 of protein synthesis was found in the substantia nigra in PD along with disease progression. Although many of these changes can be related to neuron loss in the substantia nigra, selective alteration of certain factors indicates variable degree of vulnerability of mRNAs, rRNAs and proteins in degenerating sustantia nigra. NPM1 mRNA and 18S rRNA was increased in the frontal cortex area 8 at stage 5-6; modifications were less marked and region-dependent in the angular gyrus and precuneus. Several RPs were abnormally regulated in the frontal cortex area 8 and precuneus, but only one RP in the angular gyrus, in PD. Altered levels of eIF3 and eIF1, and decrease eEF1A and eEF2 protein levels were observed in the frontal cortex in PD. No modifications were found in the putamen at any time of the study except transient modifications in 28S rRNA and only one RP mRNA at stages 5-6. These observations further indicate marked region-dependent and stage-dependent alterations in the cerebral cortex in PD. Altered solubility and α-synuclein oligomer formation, assessed in total homogenate fractions blotted with anti-α-synuclein oligomer-specific antibody, was demonstrated in the substantia nigra and frontal cortex, but not in the putamen, in PD. Dramatic increase in α-synuclein oligomers was also seen in fluorescent-activated cell sorter (FACS)-isolated nuclei in the frontal cortex in PD.
  
  
  CONCLUSIONS
  Altered machinery of protein synthesis is altered in the substantia nigra and cerebral cortex in PD being the frontal cortex area 8 more affected than the angular gyrus and precuneus; in contrast, pathways of protein synthesis are apparently preserved in the putamen. This is associated with the presence of α-synuclein oligomeric species in total homogenates; substantia nigra and frontal cortex are enriched, albeit with different band patterns, in α-synuclein oligomeric species, whereas α-synuclein oligomers are not detected in the putamen.
authors.affiliation: Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Garcia-Esparcia
authors.affiliation: Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain.
authors.forename: Karina
authors.initials: K
authors.lastname: Hernández-Ortega
authors.affiliation: Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain.
authors.forename: Anusha
authors.initials: A
authors.lastname: Koneti
authors.affiliation: Department of Genetics, Medical School, Alfonso X el Sabio University, Villanueva de la Cañada, Madrid, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Gil
authors.affiliation: Cancer Epigenetics and Biology Program, IDIBELL, Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Raul
authors.initials: R
authors.lastname: Delgado-Morales
authors.affiliation: Biology-Bellvitge Unit, Scientific and Technological Centers-University of Barcelona (CCiTUB), Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Ester
authors.initials: E
authors.lastname: Castaño
authors.affiliation: Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain.
authors.forename: Margarita
authors.initials: M
authors.lastname: Carmona
authors.affiliation: Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain. 8082ifa@gmail.com.|Institute of Neuropathology, Service of Pathologic Anatomy, Bellvitge University Hospital, carrer Feixa Llarga s/n, 08907, Hospitalet de Llobregat, Spain. 8082ifa@gmail.com.
authors.forename: Isidre
authors.initials: I
authors.lastname: Ferrer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001921:Brain / Q000378:metabolism* / Q000473:pathology*; D039621:Eukaryotic Initiation Factor-3 / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009687:Nuclear Proteins / Q000378:metabolism; D000090243:Nucleophosmin; D010300:Parkinson Disease / Q000473:pathology*; D010750:Phosphoproteins / Q000378:metabolism; D035463:Pol1 Transcription Initiation Complex Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D051844:alpha-Synuclein / Q000235:genetics / Q000378:metabolism*; D000097796:Nucleolin
chemical_list: D039621:Eukaryotic Initiation Factor-3; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D010750:Phosphoproteins; D035463:Pol1 Transcription Initiation Complex Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D051844:alpha-Synuclein; D000097796:Nucleolin; C000716967:NPM1 protein, human; C063844:transcription factor UBF