24 research outputs found

    Sub-Nuclear Localization and Tumorigenic Function of the Oncoprotein Dek.

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    The human DEK gene is overexpressed in a number of malignancies, however its potential function in the context of cancer remains unknown. DEK has been implicated in a diverse set of cellular processes, including regulation of transcription, chromatin architecture, mRNA processing, and cell signaling. Regulation of the participation of DEK in these disparate functions is thought to be achieved through differential post-translational modification. We demonstrate that a fraction of nuclear DEK is acetylated in vivo. Acetylation of DEK results in the accumulation of DEK in interchromatin granule clusters, dense sub-nuclear structures enriched in mRNA processing factors. Overexpression of the acetylase p300/CBP-associated factor was sufficient to cause migration of DEK into interchromatin granule clusters. Inhibition of transcription similarly altered the sub-nuclear distribution of DEK, causing accumulation of DEK in both interchromatin granule clusters, as well as other sub-nuclear structures. The significance of DEK overexpression in melanoma was also addressed. Metastatic melanoma lines displayed remarkably increased expression of DEK as compared to normal melanocytes. Inhibition of DEK expression by shRNA interference revealed two oncogenic contributions of DEK. Knockdown of DEK expression resulted in the induction of the cyclin-dependent kinase inhibitor p21CIP1. In some, but not all melanomas, the expression of p21CIP1 was accompanied by the induction of cellular senescence. These findings suggest that overexpression of DEK may represent an event in melanoma development required to evade tumor suppression through cell cycle arrest and senescence. In addition to its anti-senescence function, DEK overexpression in melanoma also conferred remarkable chemoresistance to both the DNA damaging agent doxorubicin and the BH3 mimetic compound TW-37. This effect was independent of p53, as inhibition of DEK expression did not alter p53 accumulation or activity in response to doxorubicin. Instead, knockdown of DEK expression sensitized melanoma through downregulation of a member of the anti-apoptotic Bcl-2 family, Mcl-1. Knockdown of DEK expression resulted in reduced activity of the mcl-1 promoter and consequently reduced mcl-1 mRNA. These results demonstrate a novel transcriptional mechanism of Mcl-1 overexpression in melanoma that confers remarkable chemoresistance. This work establishes DEK as a melanoma oncoprotein with both anti-senescence and anti-apoptotic functions.Ph.D.ImmunologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/75982/1/mkhodado_1.pd

    Transcript-indexed ATAC-seq for precision immune profiling.

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    T cells create vast amounts of diversity in the genes that encode their T cell receptors (TCRs), which enables individual clones to recognize specific peptide-major histocompatibility complex (MHC) ligands. Here we combined sequencing of the TCR-encoding genes with assay for transposase-accessible chromatin with sequencing (ATAC-seq) analysis at the single-cell level to provide information on the TCR specificity and epigenomic state of individual T cells. By using this approach, termed transcript-indexed ATAC-seq (T-ATAC-seq), we identified epigenomic signatures in immortalized leukemic T cells, primary human T cells from healthy volunteers and primary leukemic T cells from patient samples. In peripheral blood CD4+ T cells from healthy individuals, we identified cis and trans regulators of naive and memory T cell states and found substantial heterogeneity in surface-marker-defined T cell populations. In patients with a leukemic form of cutaneous T cell lymphoma, T-ATAC-seq enabled identification of leukemic and nonleukemic regulatory pathways in T cells from the same individual by allowing separation of the signals that arose from the malignant clone from the background T cell noise. Thus, T-ATAC-seq is a new tool that enables analysis of epigenomic landscapes in clonal T cells and should be valuable for studies of T cell malignancy, immunity and immunotherapy

    Low-Frequency Flow Oscillation over Airfoils near Stall

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    Low-Dose Total Skin Electron Beam Therapy Combined With Mogamulizumab for Refractory Mycosis Fungoides and Sézary Syndrome

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    Purpose: Management of patients with refractory mycosis fungoides and Sézary syndrome (SS) is often challenging, as available therapies lack durable response and consistent activity across disease compartments. Combining low-dose total skin electron beam therapy (LD-TSEBT) upfront with mogamulizumab could optimize the clinical outcome of these patients. LD-TSEBT is effective in clearing skin disease, and mogamulizumab is an antitumor immunotherapy with long-term tolerability, suggesting its potential as a maintenance therapy after maximal response. We examine the combination regimen in patients with SS who were previously treated. Methods and Materials: Two patients with SS were treated with combination LD-TSEBT and mogamulizumab. Both patients received mogamulizumab 1 mg/kg weekly × 4 and then bi-weekly; LD-TSEBT (12 Gy) was initiated within 2 days of starting mogamulizumab and given over 2-3 weeks. Safety and clinical response were evaluated. Results: Total skin electron beam therapy plus mogamulizumab (TSE-Moga) was well-tolerated without any unanticipated adverse events. Patient 1 (T4N2bM0B2) was a 63-year-old woman with 4 prior systemic therapies; time to global response with TSE-Moga was 9 weeks. Patient 2 (T4NxM0B2) was a 75-year-old man with 5 prior systemic therapies; time to global response was 4 weeks. Both patients lacked global response to their prior therapies but achieved global complete response (blood and skin) with TSE-Moga. After a follow-up of 72 weeks and 43 weeks, respectively, global complete response continued. Conclusions: TSE-Moga demonstrated excellent tolerability and promising clinical activity with ongoing global complete responses in 2 patients with refractory SS. This encouraging experience supports our ongoing clinical trial evaluating the efficacy and safety of TSE-Moga in mycosis fungoides and SS

    The DEK Nuclear Autoantigen Is a Secreted Chemotactic Factor

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    The nuclear DNA-binding protein DEK is an autoantigen that has been implicated in the regulation of transcription, chromatin architecture, and mRNA processing. We demonstrate here that DEK is actively secreted by macrophages and is also found in synovial fluid samples from patients with juvenile arthritis. Secretion of DEK is modulated by casein kinase 2, stimulated by interleukin-8, and inhibited by dexamethasone and cyclosporine A, consistent with a role as a proinflammatory molecule. DEK is secreted in both a free form and in exosomes, vesicular structures in which transcription-modulating factors such as DEK have not previously been found. Furthermore, DEK functions as a chemotactic factor, attracting neutrophils, CD8(+) T lymphocytes, and natural killer cells. Therefore, the DEK autoantigen, previously described as a strictly nuclear protein, is secreted and can act as an extracellular chemoattractant, suggesting a direct role for DEK in inflammation

    The DEK oncoprotein is a Su(var) that is essential to heterochromatin integrity

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    Heterochromatin integrity is crucial for genome stability and regulation of gene expression, but the factors involved in mammalian heterochromatin biology are only incompletely understood. Here we identify the oncoprotein DEK, an abundant nuclear protein with a previously enigmatic in vivo function, as a Suppressor of Variegation [Su(var)] that is crucial to global heterochromatin integrity. We show that DEK interacts directly with Heterochromatin Protein 1 α (HP1α) and markedly enhances its binding to trimethylated H3K9 (H3K9me3), which is key for maintaining heterochromatic regions. Loss of Dek in Drosophila leads to a Su(var) phenotype and global reduction in heterochromatin. Thus, these findings show that DEK is a key factor in maintaining the balance between heterochromatin and euchromatin in vivo
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