Cytosolic PINK1 promotes the targeting of ubiquitinated proteins to the aggresome-autophagy pathway during proteasomal stress

Gao, Ju; Li, Mengen; Qin, Siyue; Zhang, Ting; Jiang, Si‐Cong; Hu, Yuan; Deng, Yongkang; Zhang, Chenliang; You, Dujuan; Li, Hongchang; Mu, Dezhi; Zhang, Zhuohua; Jiang, Chenfanfu

doi:10.1080/15548627.2016.1147667

Cited by 39 publications

(51 citation statements)

References 55 publications

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“…It is a surprise that phosphorylation of Thr269/Ser272 in SQSTM1 is essential for the transport of the micro-aggregates. SQSTM1 is well known for its activity in the assembly of polyubiquitylated proteins into micro-aggregates and its function as an autophagy receptor to facilitate autophagosome formation around protein aggregates/aggresomes, the first step of their autophagic degradation (Gao et al, 2016;Lim et al, 2015;Matsumoto et al, 2011). Previous studies on micro-aggregate transport have been focused on AT3 and HDAC6.…”

Section: Discussionmentioning

confidence: 99%

“…Since proteins in the aggresome cannot be solubilized by mild detergent, such as 1% Triton X-100 or NP40, it is possible to analyze the localization of endogenous p38 MAPKs biochemically (Gao et al, 2016). In cells under normal physiological conditions, virtually all p38 family members were localized in the NP40-soluble fraction, but in MG132-treated cells, p38δ, but not p38β or p38γ, could be readily detected in the NP40-insoluble fraction (Fig.…”

Section: P38δ Localizes To the Aggresomesmentioning

confidence: 99%

“…SQSTM1 contains a Ub (ubiquitin)-associated domain (UbA domain) at its C-terminus, but under normal physiological conditions, it does not bind polyubiquitin chains because of steric hindrance (Bjørkøy et al, 2005;Lin et al, 2013). Proteasome inhibition stimulates its Ub-binding activity through the activation of three kinases, CK2 (casein kinase 2), ULK1 (unc-51 like autophagy activating kinase 1) and Pink1-s (short form of PTEN-induced putative kinase 1) (Gao et al, 2016;Lim et al, 2015;Matsumoto et al, 2011). After its phosphorylation, SQSTM1 binds the polyubiquitylated proteins and assembles them into micro-aggregates through self-oligomerization (Bjørkøy et al, 2005;Zatloukal et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

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p38δ MAPK regulates aggresome biogenesis by phosphorylating SQSTM1 in response to proteasomal stress

Zhang

Gao

et al. 2018

Journal of Cell Science

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Aggresome formation is a major strategy to enable cells to cope with proteasomal stress. Misfolded proteins are assembled into micro-aggregates and transported to the microtubule organizing center (MTOC) to form perinuclear aggresomes before their degradation through autophagy. So far, multiple factors have been identified as the activators of micro-aggregate formation, but much less is known about the regulatory mechanisms of their transport. Here, we report that proteasomal stress leads to the activation of p38 MAPK family members. Two of them, p38γ (MAPK12) and p38δ (MAPK13), are dispensable for micro-aggregate formation but are required for their targeting to the MTOC. Interestingly, p38δ promotes micro-aggregate transport by phosphorylating SQSTM1, a major scaffold protein that assembles soluble ubiquitylated proteins into micro-aggregates. Expression of the phospho-mimetic mutant of SQSTM1 in p38δ-knockout cells completely rescued their aggresome formation defects and enhanced their resistance to proteasomal stress to wild-type levels. This study reveals p38δ-mediated SQSTM1 phosphorylation as a critical signal for the targeting of micro-aggregates to the MTOC and provides direct evidence for the survival advantages associated with aggresome formation in cells under proteasomal stress.

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Section: Discussionmentioning

confidence: 99%

Section: P38δ Localizes To the Aggresomesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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p38δ MAPK regulates aggresome biogenesis by phosphorylating SQSTM1 in response to proteasomal stress

Zhang

Gao

et al. 2018

Journal of Cell Science

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“…Thus, the pH sensitivity may allow polyUb to perform location-specific functions. Moreover, the kinase of pUb, PINK1, is either anchored at mitochondria or exists as a soluble form in the cytosol (30). Thus, phosphorylated polyUb can be either recruited or generated onsite.…”

Section: Discussionmentioning

confidence: 99%

Ubiquitin S65 phosphorylation engenders a pH-sensitive conformational switch

Gong

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Ubiquitin (Ub) is an important signaling protein. Recent studies have shown that Ub can be enzymatically phosphorylated at S65, and that the resulting pUb exhibits two conformational states-a relaxed state and a retracted state. However, crystallization efforts have yielded only the structure for the relaxed state, which was found similar to that of unmodified Ub. Here we present the solution structures of pUb in both states obtained through refinement against state-specific NMR restraints. We show that the retracted state differs from the relaxed state by the retraction of the last β-strand and by the extension of the second α-helix. Further, we show that at 7.2, the pK a value for the phosphoryl group in the relaxed state is higher by 1.4 units than that in the retracted state. Consequently, pUb exists in equilibrium between protonated and deprotonated forms and between retracted and relaxed states, with protonated/relaxed species enriched at slightly acidic pH and deprotonated/retracted species enriched at slightly basic pH. The heterogeneity of pUb explains the inability of phosphomimetic mutants to fully mimic pUb. The pHsensitive conformational switch is likely preserved for polyubiquitin, as single-molecule FRET data indicate that pH change leads to quaternary rearrangement of a phosphorylated K63-linked diubiquitin. Because cellular pH varies among compartments and changes upon pathophysiological insults, our finding suggests that pH and Ub phosphorylation confer additional target specificities and enable an additional layer of modulation for Ub signals., a 76-residue signaling protein, is found ubiquitously in cells. Two or more Ub molecules can be covalently linked to form a diubiquitin (diUb) and then a polyubiquitin (polyUb), as an isopeptide bond is formed between the carboxylate group of one Ub (called the distal Ub) and the amine group of another Ub (called the proximal Ub). Owing to the characteristic quaternary structures of polyUb and specific interactions between polyUb and its target proteins (1, 2), a polyUb with a specific linkage can be involved in a distinctive set of cellular functions (3).The heterogeneity of Ub also arises from other types of covalent modifications. Proteomics studies have indicated that Ub is phosphorylated at multiple sites (4, 5). However, PINK1 is the only Ub kinase known to date, which specifically phosphorylates Ub at S65 (6, 7). Under normal conditions, only a fraction of Ub is S65-phosphorylated. However, upon oxidative stress, neurodegeneration, or aging, the level of S65 phosphorylation increases significantly (4, 8). S65-phosphorylated Ub (pUb) in turn can activate PARKIN, a ubiquitin ligase, and induce mitophagy (9-12). However, no other pUb-specific targets have been clearly identified, and how phosphorylation affects Ub signaling in general remains unclear.Previously, Komander and coworkers showed that pUb gives two distinct sets of NMR peaks, which correspond to the two conformational states of pUb exchanging at a slow timescale (13). Based on NMR long-r...

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“…The aggresome–autophagy system is induced as a protein quality control mechanism. When cells are no longer stressed, the aggresome is broken down into microaggregates which can be digested by autophagy (Gao et al., 2016). …”

Section: Discussionmentioning

confidence: 99%

Acute exposure to organic and inorganic sources of copper: Differential response in intestinal cell lines

Keenan

O’Sullivan

Henry

et al. 2018

Food Science & Nutrition

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ScopeCopper supplementation in nutrition has evolved from using inorganic mineral salts to organically chelated minerals but with limited knowledge of the impact at the cellular level.MethodsHere, the impact of inorganic and organic nutrient forms (glycinate, organic acid, and proteinate) of copper on the cellular level is investigated on intestinal cell lines, HT29 and Caco‐2, after a 2‐hr acute exposure to copper compounds and following a 10‐hr recovery.ResultsFollowing the 10‐hr recovery, increases were observed in proteins involved in metal binding (metallothioneins) and antioxidant response (sulfiredoxin 1 and heme oxygenase 1), and global proteomic analysis suggested recruitment of the unfolded protein response and proteosomal overloading. Copper organic acid chelate, the only treatment to show striking and sustained reactive oxygen species generation, had the greatest impact on ubiquitinated proteins, reduced autophagy, and increased aggresome formation, reducing growth in both cell lines. The least effect was noted in copper proteinate with negligible impact on aggresome formation or extended growth for either cell line.ConclusionThe type and source of copper can impact significantly at the cellular level.

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Cytosolic PINK1 promotes the targeting of ubiquitinated proteins to the aggresome-autophagy pathway during proteasomal stress

Cited by 39 publications

References 55 publications

p38δ MAPK regulates aggresome biogenesis by phosphorylating SQSTM1 in response to proteasomal stress

p38δ MAPK regulates aggresome biogenesis by phosphorylating SQSTM1 in response to proteasomal stress

Ubiquitin S65 phosphorylation engenders a pH-sensitive conformational switch

Acute exposure to organic and inorganic sources of copper: Differential response in intestinal cell lines

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