Ubiquilin immunoreactivity in cytoplasmic and nuclear inclusions in synucleinopathies, polyglutamine diseases and intranuclear inclusion body disease

Abstract

Ubiquilin-1 (UBQLN1), a member of the ubiquitin-like protein family (UBQLN1-4), is associated with neurofibrillary tangles in Alzheimer's disease (AD) and with Lewy bodies (LBs) in Parkinson's disease (PD) [7]. Mutations in UBQLN2 cause dominant X-linked amyotrophic lateral sclerosis (ALS) [4]. UBQLN2-immunoreactive neuronal cytoplasmic inclusions (NCIs) are found in the hippocampus and spinal cord in ALS with or without UBQLN2 mutation. Moreover, a distinct pattern of UBQLN2 pathology is seen in cases of ALS and frontotemporal lobar degeneration with TDP-43-positive inclusions (FTLD-TDP) showing C9ORF72-hexanucleotide repeat expansion [2], which is the most common genetic abnormality in ALS/ FTLD [3,12]. Here we report that UBQLN2 immunoreactivity is present in cytoplasmic and nuclear inclusions in various neurodegenerative diseases.Post-mortem cases of sporadic ALS (n = 5), FTLD-TDP type B (n = 4), PD (n = 5), neocortical-type DLB (n = 5), multiple system atrophy (MSA; n = 5), AD (n = 5), Pick's disease (n = 4), progressive supranuclear palsy (n = 4), corticobasal degeneration (n = 4), argyrophilic grain disease (n = 4), Huntington's disease (HD; n = 3), dentatorubral-pallidoluysian atrophy (DRPLA; n = 5), spinal and bulbar muscular atrophy (SBMA; n = 3), spinocerebellar ataxia type 1 (SCA1; n = 3), SCA2 (n = 1), SCA3 (n = 5), intranuclear inclusion body disease (INIBD; n = 5) and controls (n = 5) were utilized. Immunohistochemistry was performed as described previously [10] with the following antibodies: UBQLN2, UBQLN1, phosphorylated a-synuclein, phosphorylated tau, ubiquitin, polyglutamine and TDP-43 (Online Resource). The total number of inclusions immunostained with each antibody was counted in contiguous sections.In controls, neuronal nuclei were weakly immunolabeled with anti-UBQLN2 (Fig. 1a). UBQLN2-immunoreactive NCIs were found in the temporal cortex in FTLD-TDP (25 % relative to TDP-43-positive inclusions) as well as in the spinal cord in ALS (14 %) (Fig. 1b). In PD/DLB, both brainstem type and cortical LBs were intensely stained (Fig. 1c, d). Contiguous sections stained with anti-UB-QLN2 and anti-a-synuclein revealed that 21 % of brainstem-type LBs and 48 % of cortical LBs were positive for UBQLN2. In MSA, 82 % of glial cytoplasmic inclusions (GCIs) were positive for UBQLN2 (Fig. 1e). In HD, DRPLA, SBMA, SCA1-3 and INIBD, more than 95 % of neuronal nuclear inclusions (NNIs) were strongly immunolabeled ( Fig. 1f-l). In addition, Marinesco bodies (MBs)

Dominant-negative function of the C-terminal fragments of NBR1 and SQSTM1 generated during enteroviral infection

“…Autophagy-mediated selective recycling of the terminally misfolded proteins/aggregates serves as a key component of protein quality control and defects in this pathway have been linked to protein conformation diseases, such as bone, liver, heart and neurodegenerative diseases. 3,[19][20][21][22][23][24][25][26] Misfolded and ubiquitinated proteins are commonly detected in CVB3-infected cells and tissues, suggesting that dysfunction of the protein degradation pathway may have a role in viral pathogenesis. 7,9 We have previously demonstrated that autophagy adapter protein SQSTM1 is cleaved following CVB3 infection, resulting in the loss-of-function of SQSTM1 in selective autophagy.…”

Signature changes in ubiquilin expression in the R6/2 mouse model of Huntington’s disease

“…Longer polyglutamine tracts increase the propensity of mutant Htt protein to aggregate, forming ubiquitin-positive inclusion bodies that are a pathological hallmark of HD (Finkbeiner, 2011). Several reports indicate that Htt inclusions contain ubiquilin, a protein that functions in protein clearance through the proteasome and autophagy pathways (Doi et al, 2004; Mori et al, 2012; Rutherford et al, 2013). Interestingly, in R6/2 mice, which recapitulate many features of HD, ubiquilin proteins are not only present in Htt inclusions, but their levels decline progressively during disease progression (Safren et al, 2014).…”

Differential recruitment of UBQLN2 to nuclear inclusions in the polyglutamine diseases HD and SCA3

“…In contrast, even in 100-week-old SCA3 KI mice, when intranuclear and extranuclear inclusion pathology in the brain is maximally robust, UBQLN2 did not colocalize to nuclear inclusions in the CA1 region (Fig.3C) or to extranuclear inclusions in the striatum radiatum (Fig.3D). UBQLN1, closely related to UBQLN2, has been reported to localize to SCA3 nuclear inclusions (Mori et al, 2012). However, immunostaining with an anti-UBQLN antibody that recognizes both UBQLN1 and UBQLN2 (Fig.S1) in 50 and 100-week-old SCA3-KI mice showed neither UBQLN1 nor UBQLN2 colocalization to SCA3 nuclear inclusions (Fig.…”

“…Mutations in this protein directly cause hereditary neurodegenerative disease along the amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD) spectrum (Deng et al, 2011; Zhang and Saunders, 2009). Furthermore, studies of human brain tissue indicate that UBQLN1 and/or UBQLN2 localize to many different types of inclusions including neurofibrillary tangles in AD, Lewy bodies in Parkinson disease, and neuronal nuclear inclusions in polyQ diseases (Mori et al, 2012). There are, however, inconsistencies among published reports regarding the aggregate pathologies sequestering UBQLNs.…”

“…There are, however, inconsistencies among published reports regarding the aggregate pathologies sequestering UBQLNs. These discrepancies may reflect use of different antibodies to define co-localization (Mori et al, 2012; Rutherford et al, 2013). Pathological screening of several mouse models of neurodegenerative disease and human disease brains indicates that UBQLN2 is likely associated with polyQ disease protein aggregates but does not associate with Lewy bodies in PD, tau pathology in AD, progressive supranuclear palsy or FTD (Nolle et al, 2013; Rutherford et al, 2013).…”