Bortezomib (Velcade) is widely used for the treatment of various human cancers, however, its mechanisms of action are not fully understood, particularly in myeloid malignancies. Bortezomib is a selective and reversible inhibitor of the proteasome. Paradoxically, we find that Bortezomib induces proteasome-independent degradation of TRAF6 protein, but not mRNA, in Myelodysplastic syndrome (MDS) and Acute Myeloid Leukemia (AML) cell lines and primary cells. The reduction in TRAF6 protein coincides with Bortezomib-induced autophagy, and subsequently with apoptosis in MDS/AML cells. RNAi-mediated knockdown of TRAF6 sensitized Bortezomib-sensitive and -resistant cell lines, underscoring the importance of TRAF6 in Bortezomib-induced cytotoxicity. Bortezomib-resistant cells expressing an shRNA targeting TRAF6 were resensitized to the cytotoxic effects of Bortezomib due to down-regulation of the proteasomal subunit alpha-1 (PSMA1). To uncover the molecular consequences following loss of TRAF6 in MDS/AML cells, we applied gene expression profiling and identified an apoptosis gene signature. Knockdown of TRAF6 in MDS/AML cell lines or patient samples resulted in rapid apoptosis and impaired malignant hematopoietic stem/progenitor function. In summary, we describe novel mechanisms by which TRAF6 is regulated through Bortezomib/autophagy-mediated degradation and by which it alters MDS/AML sensitivity to Bortezomib by controlling PSMA1 expression.
Cytotoxic effects of bortezomib in myelodysplastic syndrome/acute myeloid leukemia depend on autophagy-mediated lysosomal degradation of TRAF6 and repression of PSMA1.
Treatment
View SamplesWe sought to more precisely characterize the different alpha-synuclein (aSyn) 3’UTR mRNA species in normal and PD human brain. High-throughput, whole-transcriptome sequencing of the 3’UTR ends of polyadenylated mRNA transcripts (termed pA-RNAseq; see Methods) was performed on a cohort of 17 unaffected and 17 PD cerebral cortical tissue samples. This revealed 5 aSyn 3’UTR isoforms, with lengths of 290, 480, 560, 1070 and 2520 nt. Of these, the 560 nt and 2520 nt forms were predominant. The existence and relative preponderance of these species was further confirmed by Northern Blot. We next hypothesized, that aSyn 3’UTR selection might be altered in PD. Comparison of pA-RNAseq profiles from PD and unaffected cerebral cortex samples revealed an increase in the preponderance of the long 3’UTR species (>560 nt) relative to shorter species (<560 nt). Such a relative increase in aSynL was confirmed by Quantitative real-time RT-PCR (rt-qPCR) and appeared specific for PD, as the increase was also observed by comparison to RNA from amyotrophic lateral sclerosis patient samples. We note that the modified aSyn 3’UTR selection associated with PD patient tissue was detected in cerebral cortex tissue, which typically harbors pathological evidence of the disease process without frank cell loss; thus, this phenotype is unlikely to be a secondary consequence of neurodegeneration. Overall design: Comparison of 3''UTR ends of alpha-synuclein in PD and unaffected brain cortex
Alternative α-synuclein transcript usage as a convergent mechanism in Parkinson's disease pathology.
Sex, Specimen part, Disease, Disease stage, Subject
View SamplesRetinoic acid (RA), an active derivative of the liposoluble vitamin A (retinol), acts as an important signaling molecule during embryonic development, regulating phenomenons as diverse as anterior-posterior axial patterning, forebrain and optic vesicle development, specification of hindbrain rhombomeres, pharyngeal arches and second heart field, somitogenesis, and differentiation of spinal cord neurons. This small molecule directly triggers gene activation by binding to nuclear receptors (RARs), switching them from potential repressors to transcriptional activators. The repertoire of RA-regulated genes in embryonic tissues is poorly characterized. We performed a comparative analysis of the transcriptomes of murine wild-type and Retinaldehyde Dehydrogenase 2 null-mutant (Raldh2-/-) embryos - unable to synthesize RA from maternally-derived retinol - using Affymetrix DNA microarrays. Transcriptomic changes were analyzed in two embryonic regions: anterior tissues including forebrain and optic vesicle, and posterior (trunk) tissues, at early stages preceding the appearance of overt phenotypic abnormalities. Several genes expected to be downregulated under RA deficiency appeared in the transcriptome data (e.g. Emx2, Foxg1 anteriorly, Cdx1, Hoxa1, Rarb posteriorly), whereas reverse-transcriptase-PCR and in situ hybridization performed for additional selected genes validated the changes identified through microarray analysis. Altogether, the affected genes belonged to numerous molecular pathways and cellular/organismal functions, demonstrating the pleiotropic nature of RA-dependent events. In both tissue samples, genes upregulated were more numerous than those downregulated, probably due to feedback regulatory loops. Bioinformatic clustering analysis allowed us to extract groups of genes displaying similar behaviors in mutant tissue samples. These data give an overview of the gene expression changes occurring under a state of embryonic RA deficiency, and provide new candidate genes and pathways for a better understanding of retinoid-dependent molecular events.
Transcriptomic analysis of murine embryos lacking endogenous retinoic acid signaling.
Specimen part
View SamplesWe determined the Taf4 dependent differential expression of RNAs in WT as well as KO cells in their pluripotent state, before and after treatment with retinoic acid and immediately before plating to form neuronal precursors. Overall design: Examination of RNA expression in 4 different cell lines (2 independent Taf4 WT and 2 independent Taf4 KO) in ES cells and at 3 timepoints during differentiation into neurons.
Essential role of the TFIID subunit TAF4 in murine embryogenesis and embryonic stem cell differentiation.
No sample metadata fields
View SamplesWe determined the Taf4 dependent differential expression of RNAs in WT as well as KO cells at day 9 of the differentiation into the cardiac lineage. Overall design: Examination of RNA expression in 4 different cell lines (2 independent Taf4 WT and 2 independent Taf4 KO) in 1 timepoint during cardiac differentiation.
Essential role of the TFIID subunit TAF4 in murine embryogenesis and embryonic stem cell differentiation.
No sample metadata fields
View SamplesAneuploidy, a state of karyotype imbalance, is a hallmark of cancer. Changes in chromosome copy number have been proposed to drive disease by modulating the dosage of cancer driver genes and by promoting cancer genome evolution. Given the potential of cells with abnormal karyotypes to become cancerous, do pathways exist that limit the prevalence of such cells? By investigating the immediate consequences of aneuploidy on cell physiology, we identified mechanisms that eliminate aneuploid cells. We find that chromosome mis-segregation leads to replication stress, generating further genomic instability, increased karyotype complexity, and ultimately cell cycle arrest. Cells with complex karyotypes exhibit features of senescence and a pro-inflammatory response that promotes their clearance by the immune system. We propose that cells with abnormal karyotypes generate a signal for their own elimination that might well be a source of cancer cell immunosurveillance that must be overcome during malignant transformation. Overall design: Assay the transcriptional impact of aneuploidy by comparing the transcriptomes Euploid control RPE-1 cells in Aneuploid cycling RPE-1 cells and Aneuploid arrested RPE-1 cells using RNA-Seq.
Chromosome Mis-segregation Generates Cell-Cycle-Arrested Cells with Complex Karyotypes that Are Eliminated by the Immune System.
Cell line, Treatment, Subject
View SamplesAfrican-American (AA) men experience increased risk of developing prostate cancers as well as increased mortality following treatment as compared to European-American (EA) men. The aim of our study was to identify biological factors with potential to predispose AA men to prostate tumor progression and metastasis.
Enhanced expression of SOS1 is detected in prostate cancer epithelial cells from African-American men.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Identification and Functional Validation of Reciprocal microRNA-mRNA Pairings in African American Prostate Cancer Disparities.
Specimen part
View SamplesProstate cancer (PCa) tends to be more aggressive and lethal in African Americans (AA) compared to European Americans (EA). To further understand the biological factors accounting for the PCa disparities observed in AA and EA patients, we performed gene profiling using Affymetrix human exon 1.0 ST arrays to identify the differentially expressed genes beween AA cancer and patient matched normal tissues.
Identification and Functional Validation of Reciprocal microRNA-mRNA Pairings in African American Prostate Cancer Disparities.
Specimen part
View SamplesProstate cancer (PCa) tends to be more aggressive and lethal in African Americans (AA) compared to European Americans (EA). To further understand the biological factors accounting for the PCa disparities observed in AA and EA patients, we performed gene profiling analysis using Affymetrix human exon 1.0 ST arrays to identify the differentially expressed genes in AA and EA patients.
Identification and Functional Validation of Reciprocal microRNA-mRNA Pairings in African American Prostate Cancer Disparities.
Specimen part
View Samples