Unknown,Transcriptomics,Genomics,Proteomics

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Potential Roles of miR-29a in the Molecular Pathophysiology of T-Cell Acute Lymphoblastic Leukemia

ABSTRACT: The miR-29 family is an important player in the molecular pathophysiology of distinct types of cancer, with roles that seems to depend on cellular context. Reduced miR-29 levels are associated with more aggressive disease and its overexpression in cancer and leukemic cell lines inhibits proliferation. In contrast, its overexpression in hematopoietic progenitors, promotes leukemogenesis. We explored the potential roles of miR-29a in the molecular pathophysiology of T-cell acute lymphoblastic leukemia (T-ALL). As compared to normal T-cells, miR-29a levels are extremely reduced in T-ALL and in the Jurkat cell line. Microarrays analysis in Jurkat cells, following the introduction of synthetic miR-29a mimics, revealed the down-regulation of several predicted targets, including previously described targets (DNMT3a/b, CDK6, PXDN, MCL1, PIK3R1 and CXXC6), and novel targets with roles in active DNA demethylation, such as members of the ten-eleven-translocation (TET) family and TDG. Reduced miR-29a levels contribute to altered epigenetics, as its introduction in Jurkat cells, promotes the demethylation of the AHR gene (commonly methylated in T-ALL). In T-ALL patients, miR-29a levels are significantly associated with blast counts and disease free survival. Our results highlight the relevance of miR-29 in T-ALL physiopathology, and may help to clarify some contrasting findings reported in the literature. In order to identify potential miR-29a targets in T-cell lymphoblastic leukemia, Jurkat cells were electroporated with synthetic RNA molecules corresponding to miR-29a mimics (pre-miR) or inhibitors (anti-miR); and microarray profiles were compared to the profiles of Jurkat cells eletroporated with the corresponding negative controls. Transcripts with levels reduced following the introduction of the pre-miR-29a (as compared to pre-miR-Control), or transcripts acumulated folowing introduction of the anti-miR-29a inhibitor (as compared to anti-miR-Control), were considered potential targets; and were further compared to microRNA target prediction databases. Two paired samples were used for this analysis.

ORGANISM(S): Homo sapiens

SUBMITTER: Rodrigo Panepucci

PROVIDER: E-GEOD-48063 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:MicroRNAs (miRNAs) are an evolutionarily conserved large class of small non-coding RNAs that mediate post-transcriptional silencing of genes and influence a broad spectrum of biological processes ranging from embryonic development to organismal death. Our previous study identified the miR-29 family, three paralogous species of miR-29a/b/c, as the most predominantly expressed small RNA in aged mouse brain compared to neonate one. The mouse brain miR-29 is highly astrocytic. Its expression is quiescent during early brain development, and thereafter steadily increases to a saturating level around the end of the reproductive phase. To explore the functional relevance of miR-29 expression to the neural physiology of mouse brain from the mechanistic perspective of mammalian species-specific lifespan, we here designed a gain-of-function approach through forced expression of miR-29 in astrocyte from mouse fetus and surveyed the resulting alteration in the transcriptional and translational levels. DNA microarray analyses retrieved a total of 5,589 genes showing a temporal significant expression changes in the miR-29-transfected fetal astrocytes, and classified them into two gene groups positively or negatively regulated by miR-29. Mass spectrometry (MS)-based quantification of translational products of miR-29-responsive genes identified 18 species of miR-29 target candidates. We performed functional enrichment analyses using bioinformatics resources to elucidate the biological roles of the gene sets thus identified, and obtained their expression trend that favor the processes for facilitating cell differentiation while supporting normal cell proliferation /survival, which was different from the functional signatures of miR-29 at adult stages, implying the bifunctional property of miR-29 depending on the developmental context. Our present results strongly suggest that miR-29 serves as the central coordinator to shift the global gene expression in the developing mouse brain toward matured phenotype, and through which ensure the programmed transition to the post-developmental stage that is inherently set for the mouse lifespan. DNA microarray experiment: Sample labeling, hybridization and washing were performed following the standard protocol detailed in the Agilent One-Color Microarray-Based Gene Expression Analysis ver.5.7. Briefly, a One-color Spike-Mix was diluted 1000-fold and a 5-μl aliquot of the diluted mix were added to every 0.5 μg of total RNA samples (three each of extraction replicates of miR-29-treated sample and control sample named elsewhere) prior to labeling reaction. The labeling reaction was carried out separately for the RNA samples using a Quick Amp Labeling Kit one-color, in the presence of cyanine 3-CTP. The dye-labeled target (1.6 μg as cRNA) was fragmented and hybridized on an Agilent Whole Mouse Genome 4X44K microarray at 65°C for 17 hr with a Gene Expression Hybridization Kit. The hybridized slide was washed in Gene Expression Wash Buffer 1 at room temperature for 1 min, which was followed by a wash for 1 min in Gene Expression Wash Buffer 2. The processed microarrays were scanned using an Agilent DNA Microarray Scanner. Data extraction from raw image files was done with Agilent Feature Extraction software ver.10.7.

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Potential Roles of miR-29a in the Molecular Pathophysiology of T-Cell Acute Lymphoblastic Leukemia

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