p300/CBP-associated Factor Drives DEK into Interchromatin Granule Clusters

Abstract

DEK is a mammalian protein that has been implicated in the pathogenesis of autoimmune diseases and cancer, including acute myeloid leukemia, melanoma, glioblastoma, hepatocellular carcinoma, and bladder cancer. In addition, DEK appears to participate in multiple cellular processes, including transcriptional repression, mRNA processing, and chromatin remodeling. Sub-nuclear distribution of this protein, with the attendant functional ramifications, has remained a controversial topic. Here we report that DEK undergoes acetylation in vivo at lysine residues within the first 70 N-terminal amino acids. Acetylation of DEK decreases its affinity for DNA elements within the promoter, which is consistent with the involvement of DEK in transcriptional repression. Furthermore, deacetylase inhibition results in accumulation of DEK within interchromatin granule clusters (IGCs), sub-nuclear structures that contain RNA processing factors. Overexpression of P/CAF acetylase drives DEK into IGCs, and addition of a newly developed, synthetic, cellpermeable P/CAF inhibitor blocks this movement. To our knowledge, this is the first reported example of acetylation playing a direct role in relocation of a protein to IGCs, and this may explain how DEK can function in multiple pathways that take place in distinct sub-nuclear compartments. These findings also suggest that DEK-associated malignancies and autoimmune diseases might be amenable to treatment with agents that alter acetylation.The mammalian nuclear protein DEK is associated with the pathogenesis of autoimmune diseases and cancer (1-3).Autoantibodies specific for DEK are present in patients with juvenile rheumatoid arthritis and other inflammatory diseases (4, 5), and fusion of dek and can by translocation of chromosomes 6 and 9 results in acute myeloid leukemia (6). DEK expression is also increased in multiple malignancies, including bladder cancer, hepatocellular carcinoma, glioblastoma, melanoma, T-cell large granular lymphocyte leukemia, and acute myeloid leukemia, independent of the t(6,9) chromosomal translocation (1, 2, 7-9). Indeed, a gene profile analysis of 41 adult patients with acute myeloid leukemia using quantitative real-time PCR showed that DEK is overexpressed in 98% of the cases (10). Most recently, quantitative multiplex PCR was used to precisely map the focal region of genomic gain on chromosome 6p22 in bladder cancer cells (7). Genomic mapping data identified the dek gene as being centrally located within this minimal region, suggesting DEK as an important candidate for involvement in pathogenesis of bladder cancer.DEK does not belong to any characterized protein family, and sequence similarity with other factors is limited to the SAF (scaffold attachment factor) box (11, 12), also known as the SAP domain (from SAF-A/B, acinus and PIAS) (13), a 34-amino acid motif found in nuclear factors that participates in chromatin organization, mRNA processing, and transcription. Interestingly, DEK has been implicated in all three of these nuclear events. We have previou...

The DEK Nuclear Autoantigen Is a Secreted Chemotactic Factor

“…Cells migrating to the lower chambers (ϳ10 6 ) collected from a 5-m-pore-size Transwell chemotaxis insert were washed three times with fluorescence-activated cell sorting (FACS) buffer (Dulbecco's PBS, 3% fetal bovine serum, and 0.09% NaN 3 ) and then incubated on ice with antibodies in 100 l of FACS buffer for 60 min. Cells were washed again three times in FACS buffer, fixed in 1 ml of PBS with 1% paraformaldehyde overnight at 4°C, washed three times with FACS buffer, and analyzed by EPICS XL Flow Cytometer System II software (Coulter, Miami, FL).…”

DEK over-expression promotes mitotic defects and micronucleus formation

“…20,[33][34][35][36][37] DEK is a highly modified protein, containing 57 potential phosphorylated sites and over 70 lysine residues with the potential to be poly ADPribosylated and ubiquitinated. 26,27,[38][39][40] Such modifications alter its ability to bind chromatin, re-localize, and carry out specific biological functions in a manner that remain poorly understood and have been studied primarily in cancer cells wherein DEK is over-expressed. 41 For example, DEK is phosphorylated by CK2 during interphase and phosphorylation levels appear to peak in G1.…”

Negative Regulation of the RelA/p65 Transactivation Function by the Product of the DEK Proto-oncogene

“…However, unlike the HMGI(Y) proteins, association of DEK with these promoters results in repression of transcription, possibly in association with corepressors such as HDAC2 (25) and/or through the inhibition of p300/CBP and P/CAF HAT activity (49). Interestingly, it was recently shown that P/CAF acetylates DEK at lysine residues within the first 70 amino acids of DEK resulting in decreased affinity of DEK for DNA and its accumulation in IGCs (28). Since P/CAF is required for NF-B-dependent activation of transcription (7), it is possible that the recruitment of P/CAF to promoters by activated NF-B results in the subsequent acetylation of DEK and its dissociation from the promoter.…”

“…The Absence of DEK Enhances P/CAF Recruitment to the Mcp-1 and IB␣ Promoters-Previously it was shown that P/CAF-mediated acetylation of DEK results in decreased affinity of DEK for DNA (28), indicating a functional interaction between P/CAF and DEK in transcriptional regulation. We performed ChIP assays to determine if the absence of DEK affected the recruitment of P/CAF to the Mcp-1 and IB␣ promoters.…”

“…DEK was recently shown to be acetylated by the P/CAF transcriptional coactivator protein within its N terminus resulting in a decreased affinity for DNA and accumulation in interchromatin granule clusters (IGCs) (28). Based on these results, it was proposed that coactivator-mediated acetylation of DEK displaces DEK from promoters to allow transcriptional activation (28).…”