Fbxo45-mediated degradation of the tumor-suppressor Par-4 regulates cancer cell survival

X Chen; A A Sahasrabuddhe; P Szankasi; F Chung; V Basrur; V M Rangnekar; M Pagano; M S Lim; K S J Elenitoba-Johnson

doi:10.1038/cdd.2014.92

Fbxo45-mediated degradation of the tumor-suppressor Par-4 regulates cancer cell survival

Cell Death Differ. 2014 Oct;21(10):1535-45. doi: 10.1038/cdd.2014.92. Epub 2014 Jul 4.

Authors

X Chen¹, A A Sahasrabuddhe¹, P Szankasi², F Chung¹, V Basrur¹, V M Rangnekar³, M Pagano⁴, M S Lim⁵, K S J Elenitoba-Johnson⁶

Affiliations

¹ Department of Pathology, University of Michigan Medical School, 2037 BSRB 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
² ARUP Laboratories, 500 Chipeta Way, Salt Lake City, UT 84108, USA.
³ Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY 40508, USA.
⁴ 1] Department of Pathology, NYU Cancer Institute, New York University School of Medicine, 522 First Avenue, SRB1107, New York, NY 10016, USA [2] Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
⁵ 1] Department of Pathology, University of Michigan Medical School, 2037 BSRB 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA [2] Protein Folding Disease Initiative, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
⁶ 1] Department of Pathology, University of Michigan Medical School, 2037 BSRB 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA [2] Protein Folding Disease Initiative, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA [3] Center for Computational Medicine and Bioinformatics, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.

Abstract

Prostate apoptosis response protein 4 (Par-4) also known as PRKC apoptosis WT1 regulator is a tumor suppressor that selectively induces apoptosis in cancer cells. However, its post-translational regulation by ubiquitin-mediated proteolysis and the cellular machinery that is responsible for its proteasomal degradation are unknown. Using immunopurification and an unbiased mass spectrometry-based approach, we show that Par-4 interacts with the SPRY-domain containing E3 ubiquitin ligase Fbxo45 through a short consensus sequence motif. Fbxo45 interacts with Par-4 in the cytoplasm and mediates its ubiquitylation and proteasomal degradation. Fbxo45 silencing results in stabilization of Par-4 with increased apoptosis. Importantly, a Par-4 mutant that is unable to bind Fbxo45 is stabilized and further enhances staurosporine-induced apoptosis. Co-expression of Fbxo45 with Par-4 protects cancer cells against Par-4-induced apoptosis. Our studies reveal that Fbxo45 is the substrate-receptor subunit of a functional E3 ligase for Par-4 that has a critical role in cancer cell survival.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Amino Acid Sequence
Apoptosis / genetics
Apoptosis Regulatory Proteins / genetics
Apoptosis Regulatory Proteins / metabolism*
Cell Line, Tumor
Cell Survival / genetics
DEAD-box RNA Helicases / genetics
Enzyme Inhibitors / pharmacology
F-Box Proteins / genetics
F-Box Proteins / metabolism*
HEK293 Cells
HeLa Cells
Humans
Molecular Sequence Data
Mutation
Neoplasms / metabolism*
Proteasome Endopeptidase Complex / metabolism
Protein Binding / genetics
Protein Structure, Tertiary
RNA Interference
RNA, Small Interfering
Staurosporine / pharmacology
Ubiquitin-Protein Ligases / metabolism
Ubiquitination

Substances

Apoptosis Regulatory Proteins
Enzyme Inhibitors
F-Box Proteins
FBXO45 protein, human
RNA, Small Interfering
prostate apoptosis response-4 protein
Ubiquitin-Protein Ligases
Proteasome Endopeptidase Complex
DDX4 protein, human
DEAD-box RNA Helicases
Staurosporine

Abstract

Publication types

MeSH terms

Substances

Grants and funding