Identification of a splice variant of optineurin which is defective in autophagy and phosphorylation

Moharir, Shivranjani C; Bansal, Megha; Ramachandran, Gopalakrishna; Ramaswamy, Rajashree; Rawat, Shivali; Raychaudhuri, Santwana; Swarup, Ghanshyam

doi:10.1016/j.bbamcr.2018.08.009

Cited by 15 publications

(15 citation statements)

References 47 publications

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“…Optineurin promotes aggregation of mutant huntingtin and mutant ataxin-3: Optineurin mediates autophagy dependent clearance of protein aggregates formed by mHtt and some other mutant proteins associated with neurodegenerative diseases in neuronal and non-neuronal cells (29,30). Recently we have generated Optn -/mouse embryonic fibroblasts (MEFs) which show reduced non-selective (basal and starvation induced) autophagy as seen by reduced formation of LC3-II, and lower number of autophagosomes and autolysosomes in comparison with wild type cells (36,44). We examined the formation of mHtt aggregates in Optn -/and wild type MEFs by expressing GFP tagged mHtt and observing under a fluorescence microscope.…”

Section: Resultsmentioning

confidence: 99%

“…Mouse Optn ShRNA was described in (47). GFP-mHtt 97Q was described in (36). GFP-mAtax-3 130Q was kindly provided by Dr. Nihar Ranjan Jana (43).…”

Section: Methodsmentioning

confidence: 99%

“…Optn -/and wild type MEFs have been described (36,44). MEFs and N2A cells were maintained in Dulbecco's Modified Eagle Medium (DMEM) supplemented with 10% FBS, 50 IU/ml penicillin and 50 μg/ml streptomycin in a humidified 5% CO2 incubator at 37C.…”

Section: Cell Culture and Transfectionsmentioning

confidence: 99%

“…What role optineurin plays in those aggregates is yet to be explored. The autophagy receptor function of OPTN is involved in clearance of mutant huntingtin (with expanded poly-glutamine repeats) and mutant SOD1 protein aggregates (29,30,36). A study has shown that medium projection neurons, a subset of striatal neurons, which express lower level of optineurin, are more vulnerable in Huntington's disease mouse model as compared to interneurons which express optineurin abundantly (37).…”

Section: Introductionmentioning

confidence: 99%

“…In this study, we have explored the role of optineurin in mutant protein aggregation and in cytoprotection from toxicity of mutant proteins. We have used two mutant protein models, a short fragment of huntingtin protein having 97 glutamine repeats (mHtt) (36) and, a short fragment of ataxin-3 protein having 130 glutamine repeats (mAtax-3) (43) to understand the role of optineurin in protein aggregation and cytoprotection. By using Optn -/and wild type (WT) mouse embryonic fibroblasts (MEFs), we show that optineurin promotes formation of mHtt 97Q and mAtax-3 130Q aggregates.…”

Section: Introductionmentioning

confidence: 99%

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Optineurin promotes aggregation of mutant huntingtin and mutant ataxin-3, and reduces cytotoxicity of aggregates

Moharir¹,

Ak²,

Swarup³

2020

Preprint

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Optineurin (OPTN), a cytoplasmic adaptor protein involved in cargo selective autophagy of bacteria, damaged mitochondria and mutant protein aggregates, is frequently seen in pathological structures containing protein aggregates, associated with several neurodegenerative diseases. However, the function of OPTN in these protein aggregates is not known. Here, we have explored the role of OPTN in mutant protein aggregation and in cytoprotection from toxicity of mutant proteins. Mutant huntingtin (mHtt) and mutant ataxin-3 (mAtax-3) showed reduced formation of aggregates in Optn-/- mouse embryonic fibroblasts as compared with wild type cells. Co-expression of OPTN enhanced aggregate formation by mHtt and mAtax-3 in Optn-/- cells. C-terminal domain of OPTN (412-577 amino acids) was necessary and sufficient to promote aggregate formation by these mutant proteins. The E478G mutant of OPTN, defective in ubiquitin-binding and autophagy, was also able to promote aggregation of mHtt and mAtax-3. OPTN and its C-terminal domain form a complex with the chaperone HSP70 known to promote mutant protein aggregation. Overexpression of mHtt or mAtax-3 induced more cell death in Optn-/- cells compared with wild type cells. Importantly, compared to wild type cells, Optn-deficient cells having mHtt or mAtax-3 aggregates showed higher level of cell death in neuronal (N2A) and non-neuronal cells. Our results show that OPTN promotes formation of mutant huntingtin and mutant ataxin-3 aggregates, and this function of OPTN might be mediated through interaction with HSP70 chaperones. Our results also show that OPTN reduces cytotoxicity caused by these mutant protein aggregates.

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Section: Resultsmentioning

confidence: 99%

“…Mouse Optn ShRNA was described in (47). GFP-mHtt 97Q was described in (36). GFP-mAtax-3 130Q was kindly provided by Dr. Nihar Ranjan Jana (43).…”

Section: Methodsmentioning

confidence: 99%

Section: Cell Culture and Transfectionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Optineurin promotes aggregation of mutant huntingtin and mutant ataxin-3, and reduces cytotoxicity of aggregates

Moharir¹,

Ak²,

Swarup³

2020

Preprint

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Phosphoproteomics analysis of diabetic cardiomyopathy in aging‐accelerated mice and effects of D‐pinitol

et al. 2021

Proteomics Clinical Apps

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Purpose:The molecular mechanisms of diabetic cardiomyopathy (DCM) development and D-pinitol (DP) in its treatment remain unclear. The present study is to explore the underlying mechanism of DCM in an elderly diabetic mouse model and to seek the protective targets of DP by phosphoproteomics. Experimental design:We used streptozotocin to induce diabetes in SAMP8 and DP (150 mg/kg/day) intragastrically administrated to diabetic mice for 8 weeks. The heart tissues were harvested for label-free phosphoproteomic analysis from diabetic mice. Some differentially regulated phosphorylation sites were confirmed by parallel reaction monitoring.Results: Our results showed that 612 phosphorylation sites on 454 proteins had their phosphorylation levels significantly changed in the heart of untreated diabetic mice (DM). Of these phosphorylation sites, 216 phosphorylation sites on 182 proteins were normalized after DP treatment. We analyzed the functional signaling pathways in the heart of DP treated diabetic mice (DMT), including glucagon signaling pathway, insulin signaling pathway, mitophagy, apoptosis, and longevity regulating pathway. Two consensus motifs identified were targeted by Src and epidermal growth factor receptor between DMT and DM groups. Conclusions and clinical relevance:Our study might help to better understand the mechanism of DCM, provide novel targets for estimating the protective effects of DP.

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Optineurin deficiency induces patchy hair loss but it is not sufficient to cause amyotrophic lateral sclerosis in mice

Moharir

Swarup

2022

Biochimica et Biophysica Acta (BBA) - Molecular Basis of Diseas

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Identification of a splice variant of optineurin which is defective in autophagy and phosphorylation

Cited by 15 publications

References 47 publications

Optineurin promotes aggregation of mutant huntingtin and mutant ataxin-3, and reduces cytotoxicity of aggregates

Optineurin promotes aggregation of mutant huntingtin and mutant ataxin-3, and reduces cytotoxicity of aggregates

Phosphoproteomics analysis of diabetic cardiomyopathy in aging‐accelerated mice and effects of D‐pinitol

Optineurin deficiency induces patchy hair loss but it is not sufficient to cause amyotrophic lateral sclerosis in mice

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