Characterization of age-related gene expression profiling in bone marrow and epididymal adipocytes

Abstract In multiple myeloma (MM), bone marrow-derived endothelial progenitor cells (EPCs) contribute to tumor neoangiogenesis and their levels covary with tumor mass and prognosis. Recent X-chromosome inactivation studies in female patients showed that, similar to tumor cells, EPCs are clonally restricted in MM. Genomic profiling of MM using high-resolution array comparative genomic hybridization (aCGH) has been previously utilized to mine the genome and find clinical correlates in MM patients. In this study, clonotypic aspects of bone marrow-derived EPCs and MM cells were investigated using aCGH and expression profiling analysis. Confluent EPCs were outgrown from bone marrow aspirates by adherence to laminin. EPCs were >98% vWF/CD133/KDR+ and <1% CD38+. The laminin-nonadherent bone marrow fraction enriched for tumor cells was >50% CD38+. For aCGH and for gene expression profiling, genomic DNA and total RNA from EPCs and MM cells were hybridized to human oligonucleotide arrays (Agilent Technologies) and human cDNA microarrays (Affymetrix), respectively. High resolution aCGH with segmentation analysis showed that EPCs and MM cells in one of ten cases share identical patterns of chromosomal gains and losses, while another 5 cases shared multiple focal copy number alterations (CNAs) including gains and losses. The genomes of EPCs and MM cells additionally displayed exclusive CNAs, but these were far fewer in EPCs than in MM cells. In 3 patients, EPCs harbored a common 0.6Mb deletion at 1q21 not shared by MM cells. Pertinent genes in this region that could affect proliferation and tumor suppression include N2N, NBPF10, and TXNIP. Validation studies of aCGH findings by other methods are ongoing. Gene expression profiling showed decreased expression of 1q21 region genes (e.g., calgranulin C and lamin A/C). A genome-wide comparison of patients’ MM cells and EPCs, which is focused on their shared genetic characteristics, will be presented.

Download Full-text

Nonsense-Mediated mRNA Decay Is Essential for the Hematopietic Compartement.

Blood ◽

10.1182/blood.v110.11.506.506 ◽

2007 ◽

Vol 110 (11) ◽

pp. 506-506

Author(s):

Joachim Weischenfeldt ◽

Inge Damgaard ◽

David Bryder ◽

Claus Nerlov ◽

Bo Porse

Keyword(s):

Gene Expression ◽

Bone Marrow ◽

T Cells ◽

Gene Expression Profiling ◽

Expression Profiling ◽

Mrna Decay ◽

Double Positive ◽

Mrna Pool ◽

Nonsense Mediated Mrna Decay

Abstract Nonsense-mediated mRNA decay (NMD) is a conserved cellular surveillance system that degrades mRNAs with premature termination codons (PTCs). PTC-containing transcripts can arise from faulty events such as erroneous mRNA processing events as well as mutations, and their translation may lead to the synthesis of deleterious proteins. In addition to serving as a genomic protection system, experiments in tissue culture cells have demonstrated that NMD regulates 5% of the normal mRNA pool suggesting that the NMD pathway may have a broader role in gene regulation. Finally, NMD has also been proposed to be important during lymphocyte development as a tool of riding the cells of transcripts resulting from unproductive re-arrangements events of T cell receptor and immunoglobulin genes. Although NMD has been studied extensively at the biochemical level, the actual role and importance of NMD in the mammalian organism has not been investigated. We therefore generated a conditional Upf2 knock-out mouse line (UPF2 being an essential NMD factor) which we crossed to different hematopoietic relevant Cre expressing lines. Full ablation of UPF2 (using the inducible Mx1-Cre deleter) led to complete loss of all nucleated cells in the bone marrow and death of the animals within 10 days. A similar phenotype was observed when Upf2fl/fl; Mx1Cre BM cells were transplanted into lethally irradiated WT recipients and induced with poly-IC, demonstrating the cell autonomous nature of the phenotype. Deletion of UPF2 in the myeloid lineage using the LysM-Cre deleter resulted in efficient ablation of UPF2 and the absence of NMD in reporter transfected bone marrow derived macrophages (BMDMs). However, the steady state levels of myeloid cells appeared unaltered. Finally, deletion of UPF2 in T cells using a Lck-Cre deleter led to a marked reduction of both CD4/CD8 double-positive and single-positive T cells and accumulation of PTC containing transcripts. Gene expression profiling experiments of BMDM and thymocytes from WT and UPF2-ablated animals identified a common core set of 27 up-regulated genes consistent with the role of NMD as a mRNA degrading system. The gene expression profiling data suggest that ablation of NMD leads to accumulation of unfolded proteins. In summary, these studies demonstrate the vital and cell-autonomous role of NMD in the hematopoietic system.

Download Full-text