Project description:miR-146a is a NF-κB induced microRNA that serves as a feedback regulator of this critical pathway. In mice, deficiency of miR-146a results in hematolymphoid cancer at advanced ages as a consequence of constitutive NF-κB activity. In this study, we queried whether the deficiency of miR-146a contributes to B-cell oncogenesis. Combining miR-146a deficiency with transgenic expression of c-Myc led to the development of highly aggressive B-cell malignancies. Mice transgenic for c-Myc and deficient for miR-146a were characterized by significantly shortened survival, increased lymph node involvement, differential involvement of the spleen and a mature B-cell phenotype. High-throughput sequencing of the tumors revealed significant dysregulation of approximately 250 genes. Amongst these, the transcription factor Egr1 was consistently upregulated in mice deficient for miR-146a. Interestingly, transcriptional targets of Egr1 were enriched in both the high-throughput dataset and in a larger set of miR-146a-deficient tumors. miR-146a overexpression led to downregulation of Egr1 and downstream targets with concomitant decrease in cell growth. Direct targeting of the human EGR1 by miR-146a was seen by luciferase assay. Together our findings illuminate a bona fide role for miR-146a in the modulation of B-cell oncogenesis and reveal the importance of understanding microRNA function in a cell- and disease-specific context.
Project description:Purpose: To find out the global transcriptomic change induced by overexpression of miR-146a in thymus Methods:Thymic mRNA profile of two pools from age (five to six-week old)- and gender (one male and one female for each pool)- matched wild-type (WT) and miR-146a transgenic (Tg) mice were generated by deep sequencing using Illumina HiSeq 2500. The clean reads that passed quality filters were mapped against Mus musculus genome using HotHap2, and the only uniquely mapped reads were used to calculate reads per kilobase of exon per million fragment (RPKM) values for each sample. The transcript isoform with a fold-change over 2 and q<0.001 were considered differentially expressed. Conclusion: Our study identified 101 differently expressed transcripts in thymus from miR-146a Tg mice, including 56 down-regulated transcripts covering 49 genes which are the candidate targets of miR-146a
Project description:MiR-146a is an important regulator of innate inflammatory responses and is also implicated in cell death and survival. Here, we identified microglia as the main cellular source of miR-146a among mouse CNS resident cells. We further characterized the phenotype of miR-146a KO microglia cells during in vivo demyelination induced by cuprizone (CPZ) and found reduced number of CD11c+ microglia in the KO compared to WT mice. Microglia were also isolated from the brain, and the proteome was analyzed by liquid chromatography mass spectrometry.
Project description:miR-146a acts as a negative feedback regulator of inflammation. To investigate the role of miR-146a in psoriasis psoriasiform skin inflammation was indeuced in Mir-146a-/- and wild type mice (C57BL6J) by topical applciation of imiquimod (IMQ)-cream (Aldara). Gene expression profiling (Affymetrix) was used to identify transcriptomic changes associated with psoriasis-like skin inflammation in wild type vs. miR-146a -/-mice.