Studies of Optineurin, a Glaucoma Gene

Park, Bum-Chan; Shen, Xiang; Samaraweera, Mishan; Yue, Beatrice Y.J.T.

doi:10.2353/ajpath.2006.060400

Cited by 82 publications

(74 citation statements)

References 55 publications

(100 reference statements)

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“…E50K is a mutation prevalent in patients with NTG (Rezaie et al 2002) who often suffer glaucomatous defects more severe than those without E50K mutation (Aung et al 2005). The current data, in agreement with those published previously by our laboratory and by others (Park et al 20062010; Nagabhushana et al 2010; Kryndushkin et al 2012), indicate that E50K is a gain-of-function mutation. A stronger-than-the-wild type interaction of the E50K mutant with Rab8 and TfR was observed (Figure 7A, B, C) (Nagabhushana et al 2010; Park et al 2010).…”

Section: Discussionsupporting

confidence: 94%

Effects of mutations and deletions in the human optineurin gene

et al. 2014

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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.

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Section: Discussionsupporting

confidence: 94%

Effects of mutations and deletions in the human optineurin gene

et al. 2014

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“…3A, insert, bottom right panel). The lack of major colocalization, confirmed by confocal microscopy after sequential scanning, was also demonstrated previously in human RPE and trabecular meshwork cells [17]. Golgi fragmentation (Fig.…”

Section: Resultssupporting

confidence: 85%

“…It has been noted that optineurin may form complexes with Rab8 and myosin VI [17]–[20], mediating the targeting of myosin VI to the Golgi complex and may be involved in organization of the Golgi apparatus [17], [18]. siRNA studies also suggested a role of optineurin in the exocytosis of vesicular-stomatitis-virus G protein [18].…”

Section: Introductionmentioning

confidence: 99%

Posttranslational Modifications, Localization, and Protein Interactions of Optineurin, the Product of a Glaucoma Gene

et al. 2010

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BackgroundGlaucoma is a major blinding disease. The most common form of this disease, primary open angle glaucoma (POAG), is genetically heterogeneous. One of the candidate genes, optineurin, is linked principally to normal tension glaucoma, a subtype of POAG. The present study was undertaken to illustrate the basic characteristics of optineurin.Methodology/Principal FindingsLysates from rat retinal ganglion RGC5 cells were subjected to N- or O-deglycosylation or membrane protein extraction. The phosphorylation status was evaluated after immunoprecipitation. It was found that while phosphorylated, optineurin was neither N- nor O-glycosylated, and was by itself not a membrane protein. RGC5 and human retinal pigment epithelial cells were double stained with anti-optineurin and anti-GM130. The endogenous optineurin exhibited a diffuse, cytoplasmic distribution, but a population of the protein was associated with the Golgi apparatus. Turnover experiments showed that the endogenous optineurin was relatively short-lived, with a half-life of approximately 8 hours. Native blue gel electrophoresis revealed that the endogenous optineurin formed homohexamers. Optineurin also interacted with molecules including Rab8, myosin VI, and transferrin receptor to assemble into supermolecular complexes. When overexpressed, optineurin–green fluorescence protein (GFP) fusion protein formed punctate structures termed “foci” in the perinuclear region. Treatment of nocadazole resulted in dispersion of the optineurin foci. In addition, tetracycline-regulated optineurin-GFPs expressing RGC5 stable cell lines were established for the first time.Conclusions/SignificanceThe present study provides new information regarding basic characteristics of optineurin that are important for future efforts in defining precisely how optineurin functions normally and how mutations may result in pathology. The inducible optineurin-GFP–expressing cell lines are also anticipated to facilitate in-depth studies of optineurin. Furthermore, the demonstrations that optineurin is an aggregation-prone protein and that the foci formation is microtubule-dependent bear similarities to features documented in neurodegenerative diseases, supporting a neurodegenerative paradigm for glaucoma.

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“…64 Optn was initially reported to be present in the aqueous humor, suggesting that it may be a secreted protein, although this observation has not been confirmed. 2,65,66 The molecular mechanisms by which Optn mutations lead to POAG has not been established so far. It was observed that overexpression of Optn can protect cells from hydrogen peroxide-induced cell death and can block Cytochrome C release from mitochondria, a Figure 5.…”

Section: Optn and Diseasesmentioning

confidence: 99%