Proteasome Composition and Activity Changes in Cultured Fibroblasts Derived From Mucopolysaccharidoses Patients and Their Modulation by Genistein.

Karolina Pierzynowska,Magdalena Podlacha,Lidia Gaffke,Grzegorz Węgrzyn,Ewa Wieczerzak,Estera Rintz,Elżbieta Jankowska,Julia Witkowska

doi:10.3389/fcell.2020.540726

Karolina Pierzynowska, Magdalena Podlacha + Show 6 more

Open Access

https://doi.org/10.3389/fcell.2020.540726

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Abstract

In this study, we have asked whether proteasome composition and function are affected in cells derived from patients suffering from all types of mucopolysaccharidosis (MPS), an inherited metabolic disease caused by accumulation of undegraded glycosaminoglycans (GAGs). Moreover, we have tested if genistein, a small molecule proposed previously as a potential therapeutic agent in MPS, can modulate proteasomes, which might shed a new light on the molecular mechanisms of action of this isoflavone as a potential drug for macromolecule storage diseases. Significant changes in expression of various proteasome-linked genes have been detected during transcriptomic (RNA-seq) analyses in vast majority of MPS types. These results were corroborated by demonstration of increased proteasomal activities in MPS cells. However, GAGs were not able to stimulate the 26S proteasome in vitro, suggesting that the observed activation in cells is indirect rather than arising from direct GAG-proteasome interactions. Genistein significantly reduced proteasomal activities in fibroblasts derived from patients suffering from all MPS types, while its effects on in vitro 26S proteasome activity were negligible. Unexpectedly, levels of many proteasomal subunits were increased in genistein-treated MPS cells. On the other hand, this ostensible discrepancy between results of experiments designed for estimation of effects of genistein on proteasome activities and abundance of proteasomal subunits can be explained by demonstration that in the presence of this isoflavone, levels of ubiquitinated proteins were decreased. The genistein-mediated reduction of proteasomal activities might have beneficial effects in cells of MPS patients due to potential increasing of residual activities of defective lysosomal enzymes which would otherwise be subjected to efficient ubiquitination and proteasomal degradation as misfolded proteins. These results indicate another activity of genistein (apart from previously demonstrated reduction of GAG synthesis efficiency, stimulation of lysosomal biogenesis, and activation of the autophagy process) which can be beneficial in the use of this small molecule in treatment of MPS.

Highlights

Mucopolysaccharidoses (MPS) consist of a group of macromolecule storage disorders in which mutations in single genes coding for enzymes responsible for degradation of glycosaminoglycans (GAGs) cause accumulation of these compounds in lysosomes (Tomatsu et al, 2018)
To test if proteasome composition and activity can be changed in MPS, we have started our study from performing largescale transcriptomic analysis
MPS is a group of monogenic diseases (Tomatsu et al, 2018), recent studies indicated that in each MPS type there are significant changes in expression of hundreds of genes (Gaffke et al, 2020)

Summary

Introduction

Mucopolysaccharidoses (MPS) consist of a group of macromolecule storage disorders in which mutations in single genes coding for enzymes responsible for degradation of glycosaminoglycans (GAGs) cause accumulation of these compounds in lysosomes (Tomatsu et al, 2018). Depending on specific enzymatic deficits and storage of particular GAGs [dermatan sulfate (DS), heparan sulfate (HS), keratan sulfate (KS), chondroitin sulfate (CS), hyaluronate), there are 11 types and subtypes of MPS distinguished (Tomatsu et al, 2018). Other potential therapies for MPS have been tested, with small molecule-mediated substrate reduction therapy (SRT) giving promising results in experiments on animal models (Malinowska et al, 2010; Jakóbkiewicz-Banecka et al, 2011; Derrick-Roberts et al, 2017; Gaffke et al, 2018)

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