Cytoskeleton/Endoplasmic Reticulum Collapse Induced by Prostaglandin J2 Parallels Centrosomal Deposition of Ubiquitinated Protein Aggregates

Maria E Figueiredo-Pereira,Kenyon D Ogburn

doi:10.1074/jbc.m600635200

Abstract

Many neurodegenerative disorders, such as Parkinson disease, exhibit inclusion bodies containing ubiquitinated proteins. The mechanisms implicated in this aberrant protein deposition remain elusive. In these disorders signs of inflammation are also apparent in the affected central nervous system areas. We show that prostaglandin J2 (PGJ2), an endogenous product of inflammation, disrupts the cytoskeleton in neuronal cells. Furthermore, PGJ2 perturbed microtubule polymerization in vitro and decreased the number of free sulfhydryl groups on tubulin cysteines. A direct effect of PGJ2 on actin was not apparent, although actin filaments were altered in cells treated with PGJ2. This cyclopentenone prostaglandin triggered endoplasmic reticulum (ER) collapse and the redistribution of ER proteins, such as calnexin and catechol-O-methyltransferase, into a large centrosomal aggregate containing ubiquitinated proteins and alpha-synuclein. The PGJ2-dependent cytoskeletal rearrangement paralleled the development of the large centrosomal aggregate. Both of these events were replicated by treating cells with colchicine, which disrupts the microtubule/ER network, but not with brefeldin A, which impairs ER/Golgi transport. PGJ2 also perturbed 26 S proteasome assembly and activity, which preceded the accumulation of ubiquitinated proteins as detergent/salt-insoluble aggregates. Our data support a mechanism by which, upon PGJ2 treatment, cytoskeleton/ER collapse coincides with the relocation of ER proteins, other potentially neighboring proteins, and ubiquitinated proteins into centrosomal aggregates. Development of these large perinuclear aggregates is associated with disruption of the microtubule/ER network. This aberrant protein deposition, triggered by a product of inflammation, may be common to other compounds that disrupt microtubules and induce protein aggregation, such as MPP+ and rotenone, found to be associated with neurodegeneration.

Highlights

Parkinson disease, amyotrophic lateral sclerosis, and Huntington disease, to liver diseases, such as Wilson disease and alcoholic hepatitis, to name a few [1]
The protein aggregates, are indicative of a malfunction of the normal process of protein turnover because they are not prevalent in healthy cells. Most of these protein aggregates are detectable with antibodies that react with ubiquitinated proteins but their major structural components vary from cell type to cell type
Our studies focus on one of the products of inflammation, prostaglandin J2 (PGJ2),3 because recent reports indicate that these cyclopentenone prostaglandins may play an important role in neurodegeneration

Summary

Introduction

Amyotrophic lateral sclerosis, and Huntington disease, to liver diseases, such as Wilson disease and alcoholic hepatitis, to name a few [1]. We found that the large perinuclear aggregate detected with the anti-calnexin (Fig. 4J) and anti-COMT (Fig. 4K) antibodies in PGJ2-treated cells was co-localized with ␥-tubulin, a centrosome marker (Fig. 5, E–H).

Results

Conclusion