Inhibitors of lysosomal function or serum starvation in control or LAMP2 deficient cells do not modify the cellular levels of Parkinson disease-associated DJ-1/PARK 7 protein.

Raúl Sánchez-Lanzas,José G Castaño,Dong-Gyu Jo

doi:10.1371/journal.pone.0201152

Abstract

Mutations in PARK7/DJ-1 gene are associated with familial autosomal recessive Parkinson disease. Recently, lysosomes and chaperone mediated autophagy (CMA) has been reported to participate in the degradation of DJ-1/PARK7 protein. Lamp-2A isoform is considered as the lysosomal receptor for the uptake of proteins being degraded by the CMA pathway. We have used several cell lines with disrupted LAMP2 gene expression and their respective control cells to test the possible role of lysosomal degradation and in particular CMA in DJ-1 /PARK7 degradation. Interruption of LAMP-2 expression did not result in an increase of the steady-state protein levels of DJ-1 /PARK7, as it would have been expected. Furthermore, no change in DJ-1 /PARK7 protein levels were observed upon inhibition of lysosomal function with NH4Cl or NH4Cl plus leupeptin, or after activation of CMA by serum starvation for 24h. Accordingly, we have not found any evidence that DJ-1 /PARK7 protein levels are regulated via lysosomal degradation or the CMA pathway.

Highlights

PARK7 /DJ-1 gene mutations are linked to autosomal recessive and early-onset clinical manifestations of Parkinson’s disease
If Lamp-2A is implicated in the degradation of DJ-1 by the chaperone mediated autophagy (CMA) pathway as reported [12], it would be expected that the interruption of LAMP2 gene expression would produce an increase in DJ-1 protein levels
The results presented here revealed that DJ-1 protein levels did not change in response to LAMP2 gene expression silencing (Fig 1) in different cell types (MEF, N2a and B-lymphoblastoid cell lines (B-LCL))

Summary

Introduction

PARK7 /DJ-1 gene mutations are linked to autosomal recessive and early-onset clinical manifestations of Parkinson’s disease. Pathogenic mutations identified in PARK7 /DJ-1 gene include CNVs (exonic deletions and truncations), and numerous missense mutations [1] [2]. Wang et al [12] recently reported that DJ-1 protein levels increase after treatment of SN4741 cells with NH4Cl or NH4Cl and leupeptin for 18h. They show that >80% of DJ-1 is degraded after prolonged (24 hrs) serum starvation, such treatment is known to activate the pathway of chaperone mediated autophagy (CMA).

Objectives

Methods

Results

Conclusion