title: Regionally different immunoreactivity for Smurf2 and pSmad2/3 in TDP-43-positive inclusions of amyotrophic lateral sclerosis.
abstract: OBJECTIVE
  Smad ubiquitination regulatory factor-2 (Smurf2), an E3 ubiquitin ligase, can interact with Smad proteins and promote their ubiquitin-dependent degradation, thereby controlling the cellular levels of these signalling mediators. We previously reported that phosphorylated Smad2/3 (pSmad2/3) was sequestered in transactive response DNA-binding protein-43 (TDP-43) inclusions in the spinal cord of patients with amyotrophic lateral sclerosis (ALS). Recent biochemical and immunohistochemical studies on spinal cord and brain of ALS patients demonstrated that the composition of the TDP-43 inclusions is regionally distinct, suggesting different underlying pathogenic processes. We aimed to elucidate regional differences in pathomechanisms and composition of TDP-43 inclusions in relation to pSmad2/3 and Smurf2.
  
  
  METHODS
  The spinal cord and brain tissues of 13 sporadic ALS (SALS) patients were investigated using immunohistochemical analysis.
  
  
  RESULTS
  TDP-43-positive inclusions in lower motor neurones of SALS patients were immunopositive for Smurf2 and pSmad2/3. Multiple immunofluorescence staining for Smurf2, pSmad2/3, TDP-43 and ubiquitin revealed co-localization of these four proteins within the inclusions in lower motor neurones of SALS patients. Furthermore, the loss of nuclear pSmad2/3 immunoreactivity was observed in cells bearing TDP-43 inclusions. In contrast, TDP-43-positive inclusions in the extramotor neurones in the brain of SALS patients were noticeably negative for Smurf2 and pSmad2/3. In addition, pSmad2/3 immunoreactivity was preserved in the nuclei of inclusion-bearing cells.
  
  
  CONCLUSIONS
  This regional difference in the expression of Smurf2 and pSmad2/3 within TDP-43-positive inclusions might be one of the pathomechanisms underlying the loss of lower motor neurones and comparatively spared cortical neurones seen in ALS.
authors.affiliation: Department of Neurology, Kansai Medical University, OsakaDepartment of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Neurology, Kansai Medical University, OsakaDepartment of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kaneko
authors.affiliation: Department of Neurology, Kansai Medical University, OsakaDepartment of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Wate
authors.affiliation: Department of Neurology, Kansai Medical University, OsakaDepartment of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Asayama
authors.affiliation: Department of Neurology, Kansai Medical University, OsakaDepartment of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: Department of Neurology, Kansai Medical University, OsakaDepartment of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Department of Neurology, Kansai Medical University, OsakaDepartment of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ito
authors.affiliation: Department of Neurology, Kansai Medical University, OsakaDepartment of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kusaka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D002479:Inclusion Bodies / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000378:metabolism*; D051899:Smad2 Protein / Q000378:metabolism*; D051900:Smad3 Protein / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein; D025801:Ubiquitin; C471641:SMURF2 protein, human; D044767:Ubiquitin-Protein Ligases