Project description:This SuperSeries is composed of the following subset Series: GSE32364: Murine blood monocyte subsets GSE32370: Regulation of monocyte functional heterogeneity by miR-146a Refer to individual Series
Project description:Monocytes and their lineage descendants serve as a central defense system against infection and injury but if uncontrolled can also promote an excessive pathological inflammatory response. Therefore a current research goal is to understand how the organism controls the number and function of monocytes and how these variables can be tailored in therapy. Considering the evidence that monocytes are heterogeneous and exist in at least two subsets committed to divergent functions, we investigated whether distinct factors regulate the balance between monocyte subset responses in vivo. We identified a microRNA (miRNA), miR-146a, which is differentially regulated both in mouse (Ly-6Chi and Ly-6Clo) and human (CD14hi and CD14lo CD16+) monocyte subsets. The single miRNA was found to significantly control the amplitude of the Ly-6Chi monocyte response during inflammatory challenge whereas it did not affect Ly-6Clo cells. miR-146a–mediated regulation was cell-intrinsic and depended on Relb, a member of the non-canonical NF-κB/Rel family, which is identified here as a novel miR-146a target. These observations provide novel mechanistic insights into the molecular events that regulate monocyte functional heterogeneity and identify therapeutic targets that can influence the quality and quantity of monocyte responses.
Project description:Monocytes and their lineage descendants serve as a central defense system against infection and injury but if uncontrolled can also promote an excessive pathological inflammatory response. Therefore a current research goal is to understand how the organism controls the number and function of monocytes and how these variables can be tailored in therapy. Considering the evidence that monocytes are heterogeneous and exist in at least two subsets committed to divergent functions, we investigated whether distinct factors regulate the balance between monocyte subset responses in vivo. We identified a microRNA (miRNA), miR-146a, which is differentially regulated both in mouse (Ly-6Chi and Ly-6Clo) and human (CD14hi and CD14lo CD16+) monocyte subsets. The single miRNA was found to significantly control the amplitude of the Ly-6Chi monocyte response during inflammatory challenge whereas it did not affect Ly-6Clo cells. miR-146a–mediated regulation was cell-intrinsic and depended on Relb, a member of the non-canonical NF-κB/Rel family, which is identified here as a novel miR-146a target. These observations provide novel mechanistic insights into the molecular events that regulate monocyte functional heterogeneity and identify therapeutic targets that can influence the quality and quantity of monocyte responses. 4 samples of splenic Ly-6Chi monocytes, 4 samples of splenic Ly-6Clo monocytes; both isolated from C57BL/6 mice. Each sample was generated by fluorecsence activated cell sorting from the pooled spleens of 10 mice.
Project description:To gain insight into the mechanisms underlying miR-146a-mediated modulation of Ly6Chigh monocyte function, we compared the expression profiles of Ly6Chigh and Ly6Clow monocytes in miR-146a+/+ (WT) versus miR-146a-/- (KO) conditions.
Project description:The Epstein Barr virus (EBV) encoded latent membrane protein-1 (LMP1) is a functional homologue of the tumor necrosis factor receptor family and contributes substantially to the oncogenic potential of EBV through activation of Nuclear Factor-kappaB (NF-kappaB). MicroRNAs (miRNAs) are a class of small RNA molecules that are involved in the regulation of cellular processes such as growth, development, and apoptosis, and have recently been linked to cancer phenotypes. Through miRNA microarray analysis, we demonstrate that LMP1 dysregulates the expression of several cellular miRNAs, including the most highly regulated of these, miR-146a. Quantitative RT-PCR analysis confirmed induced expression of miR-146a by LMP1. Analysis of miR-146a expression in EBV latency type III and type I cell lines revealed substantial expression of miR-146a in type III (which express LMP1) but not in type I cell lines. Reporter studies demonstrated that LMP1 induces miR-146a predominantly through two NF-kappaB binding sites in the miR-146a promoter and identified a role for an OCT-1 site in conferring basal and induced expression. Array analysis of cellular mRNAs expressed in Akata cells transduced with an miR-146a expressing retrovirus identified genes that are directly or indirectly regulated by miR-146a, including a group of interferon responsive genes that are inhibited by miR-146a. Since miR-146a is known to be induced by agents that activate the interferon response pathway (including LMP1), these results suggest that miR-146a functions in a negative feedback loop to modulate the intensity and/or duration of the interferon response. Keywords: microRNA expression modified by EBV encoded oncogene, LMP1
Project description:The tumor suppressor p53 is the most frequently mutated gene in human cancers, mutated in 25-30% of breast cancers. However, mutation rates differ according to breast cancer subtype, being more prevalent in aggressive estrogen receptor (ER) negative tumors, basal-like and HER2 amplified subtypes. This heterogeneity suggests that p53 may function differently across breast cancer subtypes. We used RNAi-mediated p53 knockdown (KD) and antagomir-mediated KD of microRNAs to study how gene expression and cellular response to p53 loss differ in luminal vs. basal-like breast cancer. As expected, p53 loss caused down regulation of established p53 targets (e.g. p21 and miR-34 family) and increased proliferation in both luminal and basal-like cell lines. However, some p53-dependent changes were subtype-specific, including expression of miR-134, miR-146a, and miR-181b. To study the cellular response to miR-146a upregulation in p53-impaired basal-like lines, antagomir knockdown of miR-146a was performed. KD of miR-146a caused decreased proliferation and increased apoptosis, effectively ablating the effects of p53 loss. Furthermore, we found that miR-146a upregulation decreased NF-kB expression and downregulated the NF-kB-dependent extrinsic apoptotic pathway (including TNF, FADD, and TRADD) and antagomir-mediated miR-146a KD restored expression of these components, suggesting a plausible mechanism for miR-146a-dependent cellular responses. These findings are relevant to human basal-like tumor progression in vivo, since miR-146a is highly expressed in p53-mutant basal-like breast cancers. These findings suggest that targeting miR-146a expression may have value for altering the aggressiveness of p53 mutant basal-like tumors. reference x sample
Project description:Endotoxin/LPS tolerance is a tightly regulated phenomenon, which, during infection, prevents systemic hyper-inflammation. Here we report for the first time that morphine reversal of endotoxin tolerance resulting in persistent inflammation thus contributing to septicemia and septic shock. We further report that this regulation is mediated by LPS-induced down-regulation of microRNAs 146a and 155. However, only over-expression of miR-146a, but not miR-155 abrogates morphine mediated hyper-inflammation, while antagonizing miR-146a (but not miR-155) augments morphine mediated hyper-inflammation. Hence, miR-146a could be the potential therapeutic target for morphine-mediated abrogation of endotoxin tolerance.
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:The tumor suppressor p53 is the most frequently mutated gene in human cancers, mutated in 25-30% of breast cancers. However, mutation rates differ according to breast cancer subtype, being more prevalent in aggressive estrogen receptor (ER) negative tumors, basal-like and HER2 amplified subtypes. This heterogeneity suggests that p53 may function differently across breast cancer subtypes. We used RNAi-mediated p53 knockdown (KD) and antagomir-mediated KD of microRNAs to study how gene expression and cellular response to p53 loss differ in luminal vs. basal-like breast cancer. As expected, p53 loss caused down regulation of established p53 targets (e.g. p21 and miR-34 family) and increased proliferation in both luminal and basal-like cell lines. However, some p53-dependent changes were subtype-specific, including expression of miR-134, miR-146a, and miR-181b. To study the cellular response to miR-146a upregulation in p53-impaired basal-like lines, antagomir knockdown of miR-146a was performed. KD of miR-146a caused decreased proliferation and increased apoptosis, effectively ablating the effects of p53 loss. Furthermore, we found that miR-146a upregulation decreased NF-kB expression and downregulated the NF-kB-dependent extrinsic apoptotic pathway (including TNF, FADD, and TRADD) and antagomir-mediated miR-146a KD restored expression of these components, suggesting a plausible mechanism for miR-146a-dependent cellular responses. These findings are relevant to human basal-like tumor progression in vivo, since miR-146a is highly expressed in p53-mutant basal-like breast cancers. These findings suggest that targeting miR-146a expression may have value for altering the aggressiveness of p53 mutant basal-like tumors.