We investigated a family manifesting amyotrophic lateral sclerosis (ALS) with a heterozygous E478G mutation in the optineurin (OPTN) gene. Clinically, slow deterioration of motor function, mood and personality changes, temporal lobe atrophy on neuroimaging, and bizarre finger deformity were noted. Neuropathologically, TAR DNA-binding protein 43 (TDP-43)-positive neuronal intracytoplasmic inclusions were observed in the spinal and medullary motor neurons. In these cells, the immunoreactivity of nuclear TDP-43 was reduced. Consecutive sections revealed that the inclusions were also reactive with anti-ubiquitin and anti-p62 antibodies, but noticeably negative for OPTN. In addition, TDP-43/p62-positive glial cytoplasmic inclusions (GCIs) were scattered throughout the spinal cord and the medullary motor nuclei. Furthermore, Golgi fragmentation was identified in 70% of the anterior horn cells (AHCs). The presence of AHCs with preserved nuclear TDP-43 and a fragmented Golgi apparatus, which are unrecognizable in sporadic ALS, indicates that patients with the E4787G OPTN mutation would manifest Golgi fragmentation before loss of nuclear TDP-43. In the neocortex, GCIs were sparsely scattered among the primary motor and temporal cortices, but no neuronal TDP-43-positive inclusions were detected. In the amygdala and the ambient gyrus, argyrophilic grains and ballooned neurons were seen. The thorough neuropathologic investigations performed in this work demonstrated that OPTN-positive inclusion bodies, if any, were not prominent. We postulate that optineurinopathy is closely linked with TDP-proteinopathy and speculate that this heterozygous E478G mutation would cause ALS by acting through a dominant-negative mechanism.
"Golgi fragmentation is a frequent feature in motor neurons of ALS patients, where it may occur in 10-50% of motor neurons in sporadic and SOD1-ALS patients [6,20,21] and up to 70% of the motor neurons in some patients with familial ALS and ALS-like disorders [22,23]. The occurrence of Golgi fragmentation correlates with nuclear-to-cytoplasmic redistribution of TDP-43 and the presence of TDP-43 positive inclusions in sporadic ALS motor neurons . "
[Show abstract][Hide abstract] ABSTRACT: Fragmentation of stacked cisterns of the Golgi apparatus into dispersed smaller elements is a feature associated with degeneration of neurons in amyotrophic lateral sclerosis (ALS) and some other neurodegenerative disorders. However, the role of Golgi fragmentation in motor neuron degeneration is not well understood.
Here we use a SOD1-ALS mouse model (low-copy Gurney G93A-SOD1 mouse) to show that motor neurons with Golgi fragmentation are retrogradely labeled by intramuscularly injected CTB (beta subunit of cholera toxin), indicating that Golgi fragmentation precedes neuromuscular denervation and axon retraction. We further show that Golgi fragmentation may occur in the absence of and precede two other pathological markers, i.e. somatodendritic SOD1 inclusions, and the induction of ATF3 expression. In addition, we show that Golgi fragmentation is associated with an altered dendritic organization of the Golgi apparatus, does not depend on intact apoptotic machinery, and is facilitated in transgenic mice with impaired retrograde dynein-dependent transport (BICD2-N mice). A connection to altered dynein-dependent transport also is suggested by reduced expression of endosomal markers in neurons with Golgi fragmentation, which also occurs in neurons with impaired dynein function.
Together the data indicate that Golgi fragmentation is a very early event in the pathological cascade in ALS that is associated with altered organization of intracellular trafficking.
"E478G, a missense mutation in the UBD region, is associated with ALS. Patients with heterozygous E478G mutation had later onset with slower progression (Ito et al. 2011). It was suggested that the E478G mutant might have a dominant-negative effect. "
[Show abstract][Hide abstract] ABSTRACT: Optineurin is a gene associated with normal tension glaucoma (NTG) and amyotrophic lateral sclerosis (ALS). Foci formation and functional consequences including Golgi fragmentation, impairment of vesicle trafficking and apoptosis were observed previously upon overexpression and/or mutation of optineurin.
In the current study, a total of 15 GFP tagged constructs that included NTG (E50K and 2 bp-AG insertion), ALS (exon 5 deletion, R96L, Q398X, and E478G) and non-disease (L157A and D474N) associated mutants and a series of deletion fragments were cloned into mammalian expression vectors and transfected into RGC5 and/or Neuro2A cells to evaluate whether their expression confer the optineurin phenotypes. The cells were monitored for foci formation and stained by immunofluorescence with anti-GM130 to analyze the Golgi integrity. Transferrin uptake experiments were performed to evaluate the protein trafficking process and apoptosis was assessed with the active caspase 3/7 detection kit. We demonstrated that cells expressing E50K and R96L optineurin exhibited all of the optineurin phenotypes. Q398X mutant did not induce foci formation, but triggered Golgi fragmentation, impairment of transferrin uptake and increase in apoptosis. The 2 bp-AG insertion mutant had a nuclear localization, compromised the transferrin uptake and strongly induced apoptosis. The foci formation, which might not predict the rest of the phenotypes, appeared to require both the leucine zipper and ubiquitin binding domains of the optineurin sequence. Interactions of optineurin with proteins including Rab8, myosin VI, huntingtin and transferrin receptor might directly determine whether the Golgi and protein trafficking phenotypes would be manifested. Examination of mutants and deletion fragments located at various sites of optineurin gene provide clues as to what regions of the gene may play a critical role in the development of pathologic consequences.
"Ito et al.  investigated Family 4  with a heterozygous E478G missense type OPTN mutation, and reported that neuroimaging showed medial temporal lobe atrophy. The pathomechanism causing the disease may be different dependent on a recessive and dominant mutations; ALS due to a recessive mutation is speculated to show a loss of function resulting from nonsense-mediated mRNA decay of transcription . "
[Show abstract][Hide abstract] ABSTRACT: Previous studies have shown widespread multisystem degeneration in patients with sporadic amyotrophic lateral sclerosis who develop a total locked-in state and survive under mechanical ventilation for a prolonged period of time. However, the disease progressions reported in these studies were several years after disease onset. There have been no reports of long-term follow-up with brain imaging of patients with familial amyotrophic lateral sclerosis at an advanced stage of the disease. We report the cases of siblings with amyotrophic lateral sclerosis with homozygous deletions of the exon 5 mutation of the gene encoding optineurin, in whom brain computed tomography scans were followed up for more than 20 years.
The patients were a Japanese brother and sister. The elder sister was 33 years of age at the onset of disease, which began with muscle weakness of her left lower limb. Two years later she required mechanical ventilation. She became bedridden at the age of 34, and died at the age of 57. A computed tomography scan of her brain at the age of 36 revealed no abnormality. Atrophy of her brain gradually progressed. Ten years after the onset of mechanical ventilation, atrophy of her whole brain, including the cerebral cortex, brain stem and cerebellum, markedly progressed. Her younger brother was 36 years of age at the onset of disease, which presented as muscle weakness of his left upper limb. One year later, he showed dysphagia and dysarthria, and tracheostomy ventilation was performed. He became bedridden at the age of 37 and died at the age of 55. There were no abnormal intracranial findings on brain computed tomography scans obtained at the age of 37 years. At the age of 48 years, computed tomography scans showed marked brain atrophy with ventricular dilatation. Subsequently, atrophy of the whole brain rapidly progressed as in his elder sister.
We conclude that a homozygous deletion-type mutation in the optineurin gene may be associated with widespread multisystem degeneration in amyotrophic lateral sclerosis.
Journal of Medical Case Reports 12/2011; 5(1):573. DOI:10.1186/1752-1947-5-573
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