alpha-internexin is present in the pathological inclusions of neuronal intermediate filament inclusion disease.
Neuronal intermediate filament (IF) inclusion disease (NIFID) is a novel neurological disease of early onset with a variable clinical phenotype including frontotemporal dementia, pyramidal, and extrapyramidal signs. Pathologically, in affected areas, there is neuronal loss, astrocytosis, and neuronal intracytoplasmic aggregates of abnormal neuronal IFs that contain neither tau nor alpha-synuclein. Thus, to characterize the neuronal IF protein profile of inclusions in NIFID, immunohistochemistry (IHC) was performed on 10 cases of NIFID, four normal aged controls (NL), and two cases of Alzheimer's disease (AD) using a panel of anti-neuronal IF proteins. Immunoelectron microscopy was performed on selected cases and frozen tissue from the frontal lobe of four cases was used for biochemical studies including sequential extractions and Western blotting. Based on these studies, we report here for the first time that alpha-internexin, a neuronal IF protein, is present within the inclusions of NIFID as are all three neurofilament subunits: heavy, medium, and light. Thus, all class IV neuronal IF proteins are present within the pathological inclusions of this disease. Biochemistry revealed that IF aggregates were soluble in sodium dodecyl sulfate (SDS) and no post-translational modification was detected when compared with Alzheimer's disease or aged control brains. Hence, we conclude that NIFID is characterized by the pathological cytoplasmic aggregation of all class IV neuronal IF proteins in brain. The discovery of alpha-internexin in the cytoplasmic inclusions implicates novel mechanisms of pathogenesis in NIFID and other neurological diseases with pathological accumulations of IFs.
Cairns
Nigel J
NJ
Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-4283, USA. cairns@mail.med.upenn.edu
Zhukareva
Victoria
V
Uryu
Kunihiro
K
Zhang
Bin
B
Bigio
Eileen
E
Mackenzie
Ian R A
IR
Gearing
Marla
M
Duyckaerts
Charles
C
Yokoo
Hideaki
H
Nakazato
Yoichi
Y
Jaros
Evelyn
E
Perry
Robert H
RH
Lee
Virginia M-Y
VM
Trojanowski
John Q
JQ
D000328:Adult; D017668:Age of Onset; D000544:Alzheimer Disease / Q000473:pathology; D001921:Brain / Q000033:anatomy & histology / Q000473:pathology / Q000648:ultrastructure; D002352:Carrier Proteins / Q000032:analysis*; D003586:Cytomegalovirus Infections / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000032:analysis; D007382:Intermediate Filaments / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000032:analysis; D009929:Organ Size; D016019:Survival Analysis
D002352:Carrier Proteins; D007381:Intermediate Filament Proteins; D009419:Nerve Tissue Proteins; C046643:alpha-internexin