Defining the mechanism of arsenic-induced degradation of PML
type: CreativeWork
description: Arsenic trioxide is a clinically effective treatment for the disease acute promyelocytic leukaemia (APL) which is caused by the chromosomal translocation t(15;17) which fuses the promyelocytic leukaemia (PML) protein to the retinoic receptor alpha (RARa). The PML-RARa oncoprotein disrupts normal retinoic acid signalling and the function of PML nuclear bodies (PML-NBs), subnuclear protein complexes with roles in control of apoptosis and cellular senescence. Treatment with arsenic induces rapid post translational modification of PML and with the small ubiquitin like modifier (SUMO). SUMO modification of PML recruits the SUMO targeted ubiquitin E3 ligase RNF4 via four SUMO interaction motifs within the N-terminal region of RNF4. PML is then ubiquitylated and targeted for proteasomal degradation. In APL, these events trigger degradation of PML-RARa, curing the disease. To further investigate the process of arsenic induced degradation of PML, a high content siRNA screen was designed to monitor the fate of a YFP linked version of PML after siRNA mediated knockdown of components of the ubiquitin system and arsenic treatment. RNF4 depletion prior to arsenic treatment prevented PML degradation and resulted in accumulation of PML in large, bright PML-NBs. This was used as a positive control. A library of siRNAs targeting 1067 gene products were screened to identify those which perturbed the process of arsenic mediated degradation of PML, and those which affected the stability of PML in untreated cells. A number of putative hits were identified. Depletion of the cullin RING ligase scaffold CUL3, and the NEDD8 E3 ligase DCUN1D1 resulted in striking accumulation of PML, suggesting PML may be a substrate of a CUL3 RING ligase complex. Further experiments using the inhibitor of neddylation, MLN4924 support this hypothesis. PML is expressed as a various isoforms which encode a unique C-terminal region, due to alternative splicing. The second part of this study investigated the role…
abstract: Arsenic trioxide is a clinically effective treatment for the disease acute promyelocytic leukaemia (APL) which is caused by the chromosomal translocation t(15;17) which fuses the promyelocytic leukaemia (PML) protein to the retinoic receptor alpha (RARa). The PML-RARa oncoprotein disrupts normal retinoic acid signalling and the function of PML nuclear bodies (PML-NBs), subnuclear protein complexes with roles in control of apoptosis and cellular senescence. Treatment with arsenic induces rapid post translational modification of PML and with the small ubiquitin like modifier (SUMO). SUMO modification of PML recruits the SUMO targeted ubiquitin E3 ligase RNF4 via four SUMO interaction motifs within the N-terminal region of RNF4. PML is then ubiquitylated and targeted for proteasomal degradation. In APL, these events trigger degradation of PML-RARa, curing the disease. To further investigate the process of arsenic induced degradation of PML, a high content siRNA screen was designed to monitor the fate of a YFP linked version of PML after siRNA mediated knockdown of components of the ubiquitin system and arsenic treatment. RNF4 depletion prior to arsenic treatment prevented PML degradation and resulted in accumulation of PML in large, bright PML-NBs. This was used as a positive control. A library of siRNAs targeting 1067 gene products were screened to identify those which perturbed the process of arsenic mediated degradation of PML, and those which affected the stability of PML in untreated cells. A number of putative hits were identified. Depletion of the cullin RING ligase scaffold CUL3, and the NEDD8 E3 ligase DCUN1D1 resulted in striking accumulation of PML, suggesting PML may be a substrate of a CUL3 RING ligase complex. Further experiments using the inhibitor of neddylation, MLN4924 support this hypothesis. PML is expressed as a various isoforms which encode a unique C-terminal region, due to alternative splicing. The second part of this study investigated the role…
author: Hands, Katherine J.
language: eng
keywords: PML, Arsenic, SUMO
date published: 2012
date modified: 2026-07-24T02:07:39Z
provider: University of Dundee
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Dundee