The Growth Suppressor PML Represses Transcription by Functionally and Physically Interacting with Histone Deacetylases

Abstract

The growth suppressor promyelocytic leukemia protein (PML) is disrupted by the chromosomal translocation t(15;17) in acute promyelocytic leukemia (APL). PML plays a key role in multiple pathways of apoptosis and regulates cell cycle progression. The present study demonstrates that PML represses transcription by functionally and physically interacting with histone deacetylase (HDAC). Transcriptional repression mediated by PML can be inhibited by trichostatin A, a specific inhibitor of HDAC. PML coimmunoprecipitates a significant level of HDAC activity in several cell lines. PML is associated with HDAC in vivo and directly interacts with HDAC in vitro. The fusion protein PML-RAR␣ encoded by the t(15;17) breakpoint interacts with HDAC poorly. PML interacts with all three isoforms of HDAC through specific domains, and its expression deacetylates histone H3 in vivo. Together, the results of our study show that PML modulates histone deacetylation and that loss of this function in APL alters chromatin remodeling and gene expression. This event may contribute to the development of leukemia.The nonrandom chromosomal translocation t(15;17), a cytogenetic hallmark of acute promyelocytic leukemia (APL), fuses the retinoic acid receptor ␣ gene (RAR␣) and the promyelocytic leukemia gene (PML) (8,17,34). The fusion gene PML-RAR␣ encodes a fusion protein that has been shown to interfere with leukemia cell differentiation (25,26) and to cause leukemia in animal models (11,27,32,33). Disruption of PML's growth suppressor function in APL is also believed to play a role in leukemogenesis (51). PML is a nuclear-matrixassociated protein localized in the nucleus in a distinct nuclear speckled pattern designated the PML nuclear body (NB), which is disrupted in the leukemic blasts of APL (14,15,20,75). A significant number (Ͼ90%) of APL patients can be induced to complete clinical remission by high-dose all-transretinoic acid (ATRA) or arsenic trioxide (As 2 O 3 ) therapy (16,59,60,72,74). Retinoic acid (RA) treatment induces differentiation of the leukemic blasts, rapid degradation of the fusion protein PML-RAR␣, and restoration of a normal PML NB (20,75). Recent studies demonstrated that PML-RAR␣ recruits histone deacetylase (HDAC) by directly interacting with the N-CoR-Sin3 complex through the RAR␣ portion of the fusion protein, turning the fusion protein into a strong transcription repressor for RA-responsive genes. Treating APL cells with high-dose ATRA reverses the binding of PML-RAR␣ to the N-CoR-Sin3 corepressor complex and reactivates RA-responsive genes (24,32,45). PML belongs to a family of nuclear proteins consisting of the RING finger motif and two other Cys-His domains designated the B-box motif. The region following is the ␣-helical domain, which is responsible for dimerization (57). PML is the major component of this novel NB, and many proteins associated with PML have been identified. For example, the ubiquitin-like protein modifier SUMO-1 (PIC-1 or sentrin) (7,35,36,53,62), interferon-induced protein ISG20 (23), the im...

Nuclear Domain 10 Components Promyelocytic Leukemia Protein and hDaxx Independently Contribute to an Intrinsic Antiviral Defense against Human Cytomegalovirus Infection

“…While recent work from different groups illustrated that the ability of hDaxx to associate with HDACs (22,33) appears to be responsible for the packaging of viral genomes into a transcriptionally repressive chromatin state almost immediately upon infection (46,50), the exact mechanism of PML-mediated repression still remains elusive. Although PML has likewise been reported to interact with chromatin-modifying enzymes like HDAC1 and HDAC2 (28,51) or transcriptional repressors such as SATB1 (31), conclusive evidence for a direct involvement of PML in the suppression of HCMV replication is still lacking. Since a loss of PML correlates with a dispersal of putative ND10 structures, the augmented replication efficiency of HCMV in PML-kd cells could also be an indirect effect of the dissociation of hDaxx, which might be the actual repressor, from ND10 structures that may constitute the optimal subnuclear site for viral DNA repression.…”

MageA2 restrains cellular senescence by targeting the function of PMLIV/p53 axis at the PML-NBs

“…We have recently reported that MageA2 forms active complexes with HDACs to favor deacetylation of p53; 10 here we show that MageA2 could also be found in PML-NBs impairing PML sumoylation through an HDAC-dependent mechanism. Although it has been reported that PMLIV binds slightly to HDAC3, 35 MageA2 could enhance HDAC recruitment to PML-NBs, suggesting that MageA2/HDAC3 complexes could be assembled and be functional on different nuclear domains and cellular contexts. This mechanism could explain not only the observed reduction in PML acetylation, but also that of p53 at NBs.…”

Histone Deacetylases Augment Cytokine Induction of the iNOS Gene

“…In some experiments, as indicated in the text and figure legends, trichostatin A (TSA; 200 nM) was added after transfection for 24 h before cell lysates were prepared. This concentration of TSA was chosen on the basis of its effectiveness in inhibiting HDAC activity in numerous published studies (20,21,24).…”