Pdf p62sqstm1 binds directly to atg8lc3 to facilitate. The p62 protein remains associated with the nuclear pore complexlamina fraction. Protein aggregation in amyotrophic lateral sclerosis. Some proteins aggregate in a regulated manner required for different vital functional processes in the cells whereas other protein aggregates result from misfolding caused by various stressors.
Pdf p62 is a common component of cytoplasmic inclusions in. Nov 21, 2005 the p62 bodies in the cytoplasm of hela cells are ubiquitincontaining protein aggregates. The protein p62 may have an important role in protein aggregation because it has been shown to be a shuttling factor for proteins to be degraded by the proteasome, and because it is a component of aggregates from a number of neurodegenerative diseases babu et al. The p62 protein has been reported to be present in several types of cytoplasmic inclusions in neurodegenerative diseases and other protein aggregation diseases zatloukal et al. As sequestosome 1 sqstm1p62 p62 is the common component of protein aggregates in neurodegenerative diseases 12, the role of p62 in the regulation of the formation of protein aggregates has been studied extensively 14,15. Usp10 is a driver of ubiquitinated protein aggregation and. A further understanding of these processes will not only deepen our understanding of als pathogenesis, but also may aid the development of novel therapeutic. Here, we discuss recent advances in our understanding of the molecular makeup, formation, and mechanismofaction of protein aggregates in als. Cell biology copyright 2019 the protein kinase activity of.
Sequestosome1 is a protein that in humans is encoded by the sqstm1 gene. However, a recent study suggests that p62sqstm1 may link the recognition of polyubiquitinated protein aggregates to the autophagy machinery. Dec 19, 2019 gst p62 was generated by cloning mouse p62 protein orf genebank. Requirement for p62 acetylation in the aggregation of. To test whether keap1 associates with genetic ablation of keap1 significantly compromised the clearance of puromycininduced misfolded protein aggregation. Dec 20, 2005 however, a recent study suggests that p62 sqstm1 may link the recognition of polyubiquitinated protein aggregates to the autophagy machinery. The decision to form an aggregate is largely made by chaperones and chaperoneassisted proteins.
Dec 18, 2017 formation of p62 inclusions in hepatocytes is the critical marker that distinguishes simple fatty liver from nash and predicts a poor prognostic outcome for subsequent liver carcinogenesis. Khka in turn acts as a protein kinase to phosphorylate p62 at s28, thereby blocking p62 ubiquitination and enhancing p62s aggregation with keap1 and nrf2 activation. Oxidative stimulation induces hccspecifically expressed fructokinase a khka phosphorylation at s80 by 5. Gst p62 was generated by cloning mouse p62 protein orf genebank. Ubiquitylates sqstm1p62 and suppresses protein sequestration. Apr 23, 2015 the scaffold protein p62 sqstm1 is involved in protein turnover and signaling and forms a punctate pattern in eukaryotic cells. To rule out that the aggregation of vhl and cul2 was due to p62egfp overexpression, we used p62knockdown cells and then reintroduced p62egfp, p62. An increasing body of evidence indicates that ubiquitinated cargoes are important markers of degradation. Findings reported here are the first to demonstrate that protein aggregation occurs in response to hemodynamic stress, situating pressureoverload heart. Although the concentrations used in the in vitro assays are nonphysiological, these findings have implications for the role of p62 in. Immunocytochemistry immunofluorescence antisqstm1 p62 antibody ab91526 image from traver mk et al, j biol chem. Lipotoxicity induces hepatic protein inclusions through tank. In a previous study, we noted that endogenous as well as ectopically expressed p62 was present in numerous round bodies in. We next analyzed the status of ubp62 doublepositive alisaggresomes formed during oxidative h 2o 2 and as 2o 3 or proteotoxic stress mg2 and puromycin conditions.
Paulanetoc, jennifer dahanb, ellen kiarelya, leticia a. Nucleoporin p62 p62 is a protein complex associated with the nuclear envelope. Protein aggregation is a continuous process in our cells. We next analyzed the status of ub p62 doublepositive alisaggresomes formed during oxidative h 2o 2 and as 2o 3 or proteotoxic stress mg2 and puromycin conditions.
Keap1 facilitates p62mediated ubiquitin aggregate clearance. The precise pathological effects of protein aggregation remain largely unknown, but experimental evidence hints at both gain and lossoffunction mechanisms. Protein aggregation as a cellular response to oxidative stress induced by heme and iron luiz r. However, the molecular mechanism by which lipotoxicity induces protein aggregation is currently unknown. Activated nrf2 promotes expression of genes involved in reactive oxygen species reduction, cell survival, and hcc development in mice. Doxycycline attenuates protein aggregation in cardiomyocytes. In a previous study, we noted that endogenous as well as ectopically expressed p62 was present in numerous round bodies in the perinuclear area of human hela cells lamark et al. Upregulation of p62 promotes caspase8 selfaggregation and activation by abt263, resulting in apoptosis that can be disrupted by p62 mutations at.
Request pdf p62 is a common component of cytoplasmic inclusions in protein aggregation diseases exposure of cells to stress, particularly oxidative stress, leads to misfolding of proteins and. In a previous study, we noted that endogenous as well as ectopically expressed p62 was present in numerous round bodies. In a previous study, we noted that endogenous as well as ectopically expressed p62 was present in. It is thought that the protein p62sqstm1 may play a key role in this process, based on its ability to bind both ubl domain protein lc3 and the polyubiquinated proteins in the aggresome through its uba domain 30. Aggregation of neurodegenerative diseaseassociated proteins. The selective autophagy receptor p62 forms a flexible. Reduction of p62 protein levels or interference with p62 function.
Liang zhou, hongfeng wang, haigang ren, qingsong hu, zheng ying and guanghui wang, bcl2 decreases the affinity of sqstm1 p62 to polyubiquitin chains and suppresses the aggregation of misfolded protein in neurodegenerative disease, molecular neurobiology, 10. Processes underlying aggregation in als include enhanced intrinsic aggregation propensity of als proteins, rna granule dysregulation and dysfunction of protein degradation pathways. Nrf2, keap1, and p62 direct the formation of protein aggregates. Usp10 interacted with the ubiquitin receptor p62 and the interaction augmented p62 dependent ubiquitinated protein aggregation and aggresome formation, thereby cooperatively inhibiting apoptosis. It can thus function as the missing link between protein aggregation and macroautophagy. The p62 bodies in the cytoplasm of hela cells are ubiquitincontaining protein aggregates. We provide evidence that usp10 p62 induced protein aggregates inhibit proteasome activity, which increases the amount of ubiquitinated proteins and. The p62 protein was identified in the 60kda protein band using a p62 antibody fig. The protein kinase activity of fructokinase a specifies the. We provide evidence that usp10p62induced protein aggregates inhibit proteasome activity, which increases the amount of ubiquitinated proteins and. Finally, human embryonic kidney hek cells that overexpress gfpp62 were analyzed to examine the relationship between p62 aggregation and cell survival. The human p62 protein gene is located on chromosome 5 with 8 exons and 440 amino acid residues. Regulation of glucose metabolism by p62sqstm1 through hif1. Nacyldopamine induces aggresome formation without proteasome inhibition and enhances protein aggregation via p62sqstm1 expression.
Autophagy inhibition upregulates p62 sequestosome1, an ubiquitinbinding and multifunctional protein. Pdf synergistic antibreast cancer effect of pulsatilla. Usp10 interacted with the ubiquitin receptor p62 and the interaction augmented p62dependent ubiquitinated protein aggregation and aggresome formation, thereby cooperatively inhibiting apoptosis. However, a recent study suggests that p62 sqstm1 may link the recognition of polyubiquitinated protein aggregates to the autophagy machinery. Western blotting analysis showed the protein levels of lc3i, lc3ii and p62 in mcf7 d and mdamb231 e cells treated with psd 1.
To evaluate if the ponceau sstained 60kda protein band could be a mixture of several proteins, we immunoprecipitated triple flagtagged lc3b, coomassiestained the gel after electrophoresis, and excised the 60kda band. Conclusions we conclude that protein aggregation is a proximal trigger of cardiomyocyte autophagy and that autophagic activity functions to attenuate aggregateaggresome formation in heart. P62 induced autophagy failure significantly accelerates misfolded protein aggregation. Liang zhou, hongfeng wang, haigang ren, qingsong hu, zheng ying and guanghui wang, bcl2 decreases the affinity of sqstm1p62 to polyubiquitin chains and suppresses the aggregation of misfolded protein in neurodegenerative disease, molecular neurobiology, 10. The expression of p62 is induced by cellular stress such as protein aggregation14,15 that is also regulated by cellular oxygen tension. The different domains of p62 endow its diverse functions. However, the molecular mechanism by which lipotoxicity induces protein aggregation is. Finally, human embryonic kidney hek cells that overexpress gfp p62 were analyzed to examine the relationship between p62 aggregation and cell survival. Protein aggregation in amyotrophic lateral sclerosis pdf. Protein aggregation as a cellular response to oxidative. To determine the potential mechanism of the inhibition of protein aggregation by doxy, we examined the protein expression of heat shock protein 25 hsp25 and p62sqstm1. The p62 has also been identified as a common component in protein aggregates in neurodegenerative diseases. Intracellular protein aggregation is a proximal trigger of. Mitophagy is the special autophagy, functions as the selective scavenger towards the impaired mitochondria.
Significant increases in protein aggregation and colocalization with p62 were observed in the cells of the hg group, compared with those in the cells of the ng group fig. Gstp62 was generated by cloning mouse p62 protein orf genebank. In this study we took advantage of an aggregationprone protein, comprising a novel. A missing link between protein aggregates and the autophagy machinery.
Early accumulation of p62 in neurofibrillary tangles in. Nacyldopamine induces aggresome formation without proteasome. Autophagy and p62 in cardiac proteinopathy circulation research. Strikingly, p62 and lc3 formed a shell surrounding aggregates of mutant huntingtin. Cell biology copyright 2019 the protein kinase activity. Formation of p62 inclusions in hepatocytes is the critical marker that distinguishes simple fatty liver from nash and predicts a poor prognostic outcome for subsequent liver carcinogenesis. Upregulation of p62 promotes caspase8 self aggregation and activation by abt263, resulting in apoptosis that can be disrupted by p62 mutations at its functional domains. They play critical roles in cell survival under normal conditions and during stress. It is thought that the protein p62 sqstm1 may play a key role in this process, based on its ability to bind both ubl domain protein lc3 and the polyubiquinated proteins in the aggresome through its uba domain 30. Autophagy inhibition upregulates p62sequestosome1, an ubiquitinbinding and multifunctional protein. Mitochondrial dysfunction was confirmed greatly contribute to the occurrence of neurodegenerative diseases. Formation of neurodegenerative aggresome and death.
Restoring sod activity lowered superoxide levels and rescued the defects of fip200deficient nscs. Trim16 controls assembly and degradation of protein. To answer this question, we used a mouse model of lbd that lacks p62, and found that lb. Nacyldopamine induces aggresome formation without proteasome inhibition and enhances protein aggregation via p62 sqstm1 expression.
Key words autophagy, lc3, protein aggregates, p62sqstm1. Dec 20, 2017 as sequestosome 1 sqstm1 p62 p62 is the common component of protein aggregates in neurodegenerative diseases 12, the role of p62 in the regulation of the formation of protein aggregates has been studied extensively 14,15. The scaffold protein p62sqstm1 is involved in protein turnover and signaling and forms a punctate pattern in eukaryotic cells. The ubiquitinproteasome system ups and autophagy are two distinct and interacting proteolytic systems. Cereblon suppresses the formation of pathogenic protein. Hsps play a critical role in preventing protein aggregation,14. Nov 14, 2005 the p62 protein has been reported to be present in several types of cytoplasmic inclusions in neurodegenerative diseases and other protein aggregation diseases zatloukal et al. The p62 protein interacts with ubiquitinated misfolded proteins and promotes aggresomesalis formation seibenhener et al, 2004. Pdf in eukaryotic cells shortlived proteins are degraded in a specific process by the ubiquitinproteasome system ups, whereas longlived proteins.
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