Project description:miRNAs are short regulatory single stranded RNA sequences that upon complementary binding to mRNAs lead to the inhibition or degradation of their targets. This regulatory mechanisms has been shown to play crucial roles throughout the whole life cycle of animals and plants as well as in disease. While a plethora of methods exist to predict targets of miRNA, which suggest that up to 80% of the genome is miRNA regulated, it has recently been reported that many of these predictions are false positives, cell type specific or represent non-functional binding. In order to identify the subset of real functional miRNAs and their targets, we established miRNA pathway mutants in mouse embryonic stem cells (mESC), allowing the dissection of canonical and non-canonical functions of pathway members. Additional data integration of downstream regulatory layers (CLIP-seq, ribosome profiling and MS) enabled us to follow and track down real functional miRNA-gene interactions, which reduced the miRNA genome regulation to approximately 1%.
Project description:We have identified several nucleotide motifs (caug, cgggag=S2) that promote exosome sorting of miRNA in different cell types including brown adipocytes. In order to identify which proteins might recognize and bind to these motifs, we have performed co-precipitations of proteins binding biotinylated forms of miRNAs containing the aforementioned motifs or none - using streptavidin beads incubated with brown adipocytes cell lysates. We have included two types of controls: negative poly-A control and a scramble miRNA.
Project description:Renal cell carcinoma (RCC) is one of the most common cancers worldwide with nearly non-symptomatic course till advanced stage of disease. RCC can be distinguished into three subtypes: papillary (pRCC), chromophobe (chRCC) and clear cell renal cell carcinoma (ccRCC) representing up to 75% of all RCC cases. Detection and RCC monitoring tools are limited to standard imaging techniques, in combination with non-RCC specific morphological and biochemical read-outs. RCC subtype identification relays mainly on results of pathological examination of tumor slides. Molecular, clinically applicable and ideally non-invasive tools aiding RCC management are still non-existent, although molecular characterization of RCC is relatively advanced. Hence many research efforts concentrate on identification of molecular markers that will assist with RCC sub-classification and monitoring. Due to stability and tissue-specificity miRNAs are promising candidates for such biomarkers. Here we performed a meta-analysis study, utilized seven available NGS and seven microarray RCC studies in order to identify subtype-specific expression of miRNAs. We concentrated on four potentially oncocytoma-specific miRNAs (miRNA-424-5p, miRNA-146b-5p, miRNA-183-5p, miRNA-218-5p), two pRCC (miRNA-127-3p, miRNA-139-5p) and eight ccRCC specific miRNAs (miRNA-200c-3p, miRNA-362-5p, miRNA-363-3p and miRNA-204-5p, 21-5p, miRNA-224-5p, miRNA-155-5p, miRNA-210-3p) and validated their expression in an independent sample set. Additionally, we found ccRCC-specific miRNAs to be differentially expressed in ccRCC Fuhrman grades and identified alterations in their isoform composition in tumor tissue. Our results revealed that changes in expression of selected miRNA might be potentially utilized as a tool aiding ccRCC subclass discrimination and propose a miRNA panel aiding RCC subtype distinction.
