Two mechanisms involving the autophagic and proteasomal pathways process the metastasis suppressor protein, N-myc downstream regulated gene 1
File version
Author(s)
Park, Kyung Chan
Kovacevic, Zaklina
Richardson, Des R
Griffith University Author(s)
Primary Supervisor
Other Supervisors
Editor(s)
Date
Size
File type(s)
Location
License
Abstract
N-myc downstream regulated gene 1 (NDRG1) is an intriguing metastasis suppressor protein, which plays an important role in suppressing multiple oncogenic signaling pathways. Interestingly, multiple isoforms of NDRG1 have been identified, although the molecular mechanisms involved in their generation remains elusive. Herein, we demonstrate the role of two mechanisms involving autophagic and proteasomal machinery as part of an intricate system to generate different NDRG1 isoforms. Examining multiple pancreatic cancer cell-types using immunoblotting demonstrated three major isoforms of NDRG1 at approximately 41-, 46- and 47-kDa. The top NDRG1 band at 47-kDa was shown to be processed by the proteasome, followed by autophagic metabolism of the middle NDRG1 band at 46-kDa. The role of the proteasomal and autophagic pathways in NDRG1 processing was further confirmed by co-localization analysis of confocal images using PSMD9 and LC3 as classical markers of these respective pathways. All NDRG1 isoforms were demonstrated to be, at least in part, phosphorylated forms of the protein. Inhibition of two well-characterized upstream kinases of NDRG1, namely GSK3β and SGK1, resulted in decreased levels of the top NDRG1 band. Studies demonstrated that inhibition of GSK3β decreased levels of the top 47-kDa NDRG1 band, independent of its kinase activity, and this effect was not mediated via the proteasomal pathway. In contrast, the decrease in the top NDRG1 band at 47-kDa after SGK1 inhibition, was due to suppression of its kinase activity. Overall, these studies elucidated the complex and intricate regulatory pathways involving both proteasomal and autophagic processing of the metastasis suppressor protein, NDRG1.
Journal Title
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease
Conference Title
Book Title
Edition
Volume
1865
Issue
6
Thesis Type
Degree Program
School
Publisher link
Patent number
Funder(s)
Grant identifier(s)
Rights Statement
Rights Statement
Item Access Status
Note
Access the data
Related item(s)
Subject
Biochemistry and cell biology
Medical biochemistry and metabolomics
Clinical sciences
Science & Technology
Life Sciences & Biomedicine
Biophysics
Molecular Biology
Persistent link to this record
Citation
Sahni, S; Park, KC; Kovacevic, Z; Richardson, DR, Two mechanisms involving the autophagic and proteasomal pathways process the metastasis suppressor protein, N-myc downstream regulated gene 1, Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 2019, 1865 (6), pp. 1361-1378