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The Inhibition of Heat Shock Protein 90 Facilitates the Degradation of Poly-Alanine Expanded Poly (A) Binding Protein Nuclear 1 via the Carboxyl Terminus of Heat Shock Protein 70-Interacting Protein.

Shi C, Huang X, Zhang B, Zhu D, Luo H, Lu Q, Xiong WC, Mei L, Luo S - PLoS ONE (2015)

Bottom Line: Treatment with the HSP90 inhibitor 17-AAG disrupted the interaction of mutant PABPN1 with HSP90 and reduced the formation of intranuclear inclusions (INIs).Furthermore, mutant PABPN1 was preferentially degraded in the presence of 17-AAG compared with wild-type PABPN1 in vitro and in vivo.The effect of 17-AAG was mediated through an increase in the interaction of PABPN1 with the carboxyl terminus of heat shock protein 70-interacting protein (CHIP).

View Article: PubMed Central - PubMed

Affiliation: Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China.

ABSTRACT

Background: Since the identification of poly-alanine expanded poly(A) binding protein nuclear 1 (PABPN1) as the genetic cause of oculopharyngeal muscular dystrophy (OPMD), considerable progress has been made in our understanding of the pathogenesis of the disease. However, the molecular mechanisms that regulate the onset and progression of the disease remain unclear.

Results: In this study, we show that PABPN1 interacts with and is stabilized by heat shock protein 90 (HSP90). Treatment with the HSP90 inhibitor 17-AAG disrupted the interaction of mutant PABPN1 with HSP90 and reduced the formation of intranuclear inclusions (INIs). Furthermore, mutant PABPN1 was preferentially degraded in the presence of 17-AAG compared with wild-type PABPN1 in vitro and in vivo. The effect of 17-AAG was mediated through an increase in the interaction of PABPN1 with the carboxyl terminus of heat shock protein 70-interacting protein (CHIP). The overexpression of CHIP suppressed the aggregation of mutant PABPN1 in transfected cells.

Conclusions: Our results demonstrate that the HSP90 molecular chaperone system plays a crucial role in the selective elimination of abnormal PABPN1 proteins and also suggest a potential therapeutic application of the HSP90 inhibitor 17-AAG for the treatment of OPMD.

No MeSH data available.


Related in: MedlinePlus

A model for the HSP90-mediated regulation of PABPN1.The blockade of HSP90 activity induces the ubiquitination and degradation of mutant A17-PABPN1 in a CHIP-dependent manner. Our findings establish that both HSP90 and CHIP play critical roles in the process of ubiquitination and degradation of mutant A17-PABPN1 proteins.
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pone.0138936.g007: A model for the HSP90-mediated regulation of PABPN1.The blockade of HSP90 activity induces the ubiquitination and degradation of mutant A17-PABPN1 in a CHIP-dependent manner. Our findings establish that both HSP90 and CHIP play critical roles in the process of ubiquitination and degradation of mutant A17-PABPN1 proteins.

Mentions: Because CHIP co-immunoprecipitates with A10-PABPN1 and A17-PABPN1 and this interaction is increased by 17-AAG (Fig 6A and 6B), we further tested the potential involvement of CHIP in the ubiquitination of the PABPN1 proteins. A17-PABPN1 was transfected into C2C12 cells with or without the CHIP construct. The cell lysates were then processed for immunoprecipitation using an anti-GFP antibody. As shown in (Fig 6D), CHIP enhanced the level of ubiquitination of A17-PABPN1. This enhancing effect was further increased by treatment with MG-132. Consistent with these results, overexpression of ubiquitin facilitated the degradation of A17-PABPN1 (S3 Fig). Because CHIP promotes the ubiquitination of mutant A17-PABPN1 proteins, we expected that its overexpression would increase the rate of degradation of mutant A17-PABPN1 proteins by proteasomes. As shown in (Fig 6E), the overexpression of CHIP reduced the aggregation of mutant A17-PABPN1. The K30A and H260Q mutants of CHIP [40, 41] lacked this suppressive effect on aggregation. Taken together, these results suggest that the blockade of HSP90 activity by 17-AAG induces A17-PABPN1 ubiquitination and degradation in a CHIP-dependent manner (Fig 7).


The Inhibition of Heat Shock Protein 90 Facilitates the Degradation of Poly-Alanine Expanded Poly (A) Binding Protein Nuclear 1 via the Carboxyl Terminus of Heat Shock Protein 70-Interacting Protein.

Shi C, Huang X, Zhang B, Zhu D, Luo H, Lu Q, Xiong WC, Mei L, Luo S - PLoS ONE (2015)

A model for the HSP90-mediated regulation of PABPN1.The blockade of HSP90 activity induces the ubiquitination and degradation of mutant A17-PABPN1 in a CHIP-dependent manner. Our findings establish that both HSP90 and CHIP play critical roles in the process of ubiquitination and degradation of mutant A17-PABPN1 proteins.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4587574&req=5

pone.0138936.g007: A model for the HSP90-mediated regulation of PABPN1.The blockade of HSP90 activity induces the ubiquitination and degradation of mutant A17-PABPN1 in a CHIP-dependent manner. Our findings establish that both HSP90 and CHIP play critical roles in the process of ubiquitination and degradation of mutant A17-PABPN1 proteins.
Mentions: Because CHIP co-immunoprecipitates with A10-PABPN1 and A17-PABPN1 and this interaction is increased by 17-AAG (Fig 6A and 6B), we further tested the potential involvement of CHIP in the ubiquitination of the PABPN1 proteins. A17-PABPN1 was transfected into C2C12 cells with or without the CHIP construct. The cell lysates were then processed for immunoprecipitation using an anti-GFP antibody. As shown in (Fig 6D), CHIP enhanced the level of ubiquitination of A17-PABPN1. This enhancing effect was further increased by treatment with MG-132. Consistent with these results, overexpression of ubiquitin facilitated the degradation of A17-PABPN1 (S3 Fig). Because CHIP promotes the ubiquitination of mutant A17-PABPN1 proteins, we expected that its overexpression would increase the rate of degradation of mutant A17-PABPN1 proteins by proteasomes. As shown in (Fig 6E), the overexpression of CHIP reduced the aggregation of mutant A17-PABPN1. The K30A and H260Q mutants of CHIP [40, 41] lacked this suppressive effect on aggregation. Taken together, these results suggest that the blockade of HSP90 activity by 17-AAG induces A17-PABPN1 ubiquitination and degradation in a CHIP-dependent manner (Fig 7).

Bottom Line: Treatment with the HSP90 inhibitor 17-AAG disrupted the interaction of mutant PABPN1 with HSP90 and reduced the formation of intranuclear inclusions (INIs).Furthermore, mutant PABPN1 was preferentially degraded in the presence of 17-AAG compared with wild-type PABPN1 in vitro and in vivo.The effect of 17-AAG was mediated through an increase in the interaction of PABPN1 with the carboxyl terminus of heat shock protein 70-interacting protein (CHIP).

View Article: PubMed Central - PubMed

Affiliation: Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China.

ABSTRACT

Background: Since the identification of poly-alanine expanded poly(A) binding protein nuclear 1 (PABPN1) as the genetic cause of oculopharyngeal muscular dystrophy (OPMD), considerable progress has been made in our understanding of the pathogenesis of the disease. However, the molecular mechanisms that regulate the onset and progression of the disease remain unclear.

Results: In this study, we show that PABPN1 interacts with and is stabilized by heat shock protein 90 (HSP90). Treatment with the HSP90 inhibitor 17-AAG disrupted the interaction of mutant PABPN1 with HSP90 and reduced the formation of intranuclear inclusions (INIs). Furthermore, mutant PABPN1 was preferentially degraded in the presence of 17-AAG compared with wild-type PABPN1 in vitro and in vivo. The effect of 17-AAG was mediated through an increase in the interaction of PABPN1 with the carboxyl terminus of heat shock protein 70-interacting protein (CHIP). The overexpression of CHIP suppressed the aggregation of mutant PABPN1 in transfected cells.

Conclusions: Our results demonstrate that the HSP90 molecular chaperone system plays a crucial role in the selective elimination of abnormal PABPN1 proteins and also suggest a potential therapeutic application of the HSP90 inhibitor 17-AAG for the treatment of OPMD.

No MeSH data available.


Related in: MedlinePlus