Regulated transcription controls the diversity, developmental pathways and spatial organization of the hundreds of cell types that make up a mammal. Using single-molecule cDNA sequencing, we mapped transcription start sites (TSSs) and their usage in human and mouse primary cells, cell lines and tissues to produce a comprehensive overview of mammalian gene expression across the human body. We find that few genes are truly ‘housekeeping’, whereas many mammalian promoters are composite entities composed of several closely separated TSSs, with independent cell-type-specific expression profiles. TSSs specific to different cell types evolve at different rates, whereas promoters of broadly expressed genes are the most conserved. Promoter-based expression analysis reveals key transcription factors defining cell states and links them to binding-site motifs. The functions of identified novel transcripts can be predicted by coexpression and sample ontology enrichment analyses. The functional annotation of the mammalian genome 5 (FANTOM5) project provides comprehensive expression profiles and functional annotation of mammalian cell-type-specific transcriptomes with wide applications in biomedical research.

MicroRNAs (miRNAs) are short non-coding RNAs with key roles in cellular regulation. As part of the fifth edition of the Functional Annotation of Mammalian Genome (FANTOM5) project, we created an integrated expression atlas of miRNAs and their promoters by deep-sequencing 492 short RNA (sRNA) libraries, with matching Cap Analysis Gene Expression (CAGE) data, from 396 human and 47 mouse RNA samples. Promoters were identified for 1,357 human and 804 mouse miRNAs and showed strong sequence conservation between species. We also found that primary and mature miRNA expression levels were correlated, allowing us to use the primary miRNA measurements as a proxy for mature miRNA levels in a total of 1,829 human and 1,029 mouse CAGE libraries. We thus provide a broad atlas of miRNA expression and promoters in primary mammalian cells, establishing a foundation for detailed analysis of miRNA expression patterns and transcriptional control regions.

To comprehensively characterize microRNA (miRNA) expression in breast cancer, we performed the first extensive next-generation sequencing expression analysis of this disease. We sequenced small RNA from tumors with paired samples of normal and tumor-adjacent breast tissue. Our results indicate that tumor identity is achieved mainly by variation in the expression levels of a common set of miRNAs rather than by tissue-specific expression. We also report 361 new, well-supported miRNA precursors. Nearly two-thirds of these new genes were detected in other human tissues and 49% of the miRNAs were found associated with Ago2 in MCF7 cells. Ten percent of the new miRNAs are located in regions with high-level genomic amplifications in breast cancer. A new miRNA is encoded within the ERBB2/Her2 gene and amplification of this gene leads to overexpression of the new miRNA, indicating that this potent oncogene and important clinical marker may have two different biological functions. In summary, our work substantially expands the number of known miRNAs and highlights the complexity of small RNA expression in breast cancer. Cancer Res; 71(1); 78-86. Ó2011 AACR.

We analyzed 34 cases of urothelial carcinomas by miRNA, mRNA and genomic profiling. Unsupervised hierarchical clustering using expression information for 300 miRNAs produced 3 major clusters of tumors corresponding to Ta, T1 and T2-T3 tumors, respectively. A subsequent SAM analysis identified 51 miRNAs that discriminated the 3 pathological subtypes. A score based on the expression levels of the 51 miRNAs, identified muscle invasive tumors with high precision and sensitivity. MiRNAs showing high expression in muscle invasive tumors included miR-222 and miR125b and in Ta tumors miR-10a. A miRNA signature for FGFR3 mutated cases was also identified with miR-7 as an important member. MiR-31, located in 9p21, was found to be homozygously deleted in 3 cases and miR-452 and miR-452* were shown to be over expressed in node positive tumors. In addition, these latter miRNAs were shown to be excellent prognostic markers for death by disease as outcome. The presented data shows that pathological subtypes of urothelial carcinoma show distinct miRNA gene expression signatures.

Vault particles are conserved organelles implicated in multidrug resistance and intracellular transport. They contain three different proteins and non-coding vault RNAs (vRNAs). Here we show that human vRNAs produce several small RNAs (svRNAs) by mechanisms different from those in the canonical microRNA (miRNA) pathway. At least one of these svRNAs, svRNAb, associates with Argonaute proteins to guide sequence-specific cleavage and regulate gene expression similarly to miRNAs. We demonstrate that svRNAb downregulates CYP3A4, a key enzyme in drug metabolism. Our findings expand the repertoire of small regulatory RNAs and assign, for the first time, a function to vRNAs that may help explain the association between vault particles and drug resistance.

Next-generation sequencing experiments have shown that microRNAs (miRNAs) are expressed in many different isoforms (isomiRs), whose biological relevance is often unclear. We found that mature miR-21, the most widely researched miRNA because of its importance in human disease, is produced in two prevalent isomiR forms that differ by 1 nt at their 3′ end, and moreover that the 3′ end of miR-21 is posttranscriptionally adenylated by the noncanonical poly(A) polymerase PAPD5. PAPD5 knockdown caused an increase in the miR-21 expression level, suggesting that PAPD5-mediated adenylation of miR-21 leads to its degradation. Exoribonuclease knockdown experiments followed by small-RNA sequencing suggested that PARN degrades miR-21 in the 3′-to-5′ direction. In accordance with this model, microarray expression profiling demonstrated that PAPD5 knockdown results in a down-regulation of miR-21 target mRNAs. We found that disruption of the miR-21 adenylation and degradation pathway is a general feature in tumors across a wide range of tissues, as evidenced by data from The Cancer Genome Atlas, as well as in the noncancerous proliferative disease psoriasis. We conclude that PAPD5 and PARN mediate degradation of oncogenic miRNA miR-21 through a tailing and trimming process, and that this pathway is disrupted in cancer and other proliferative diseases.nucleotidyl transferase | microRNA processing

UruguayMicroRNAs (miRNAs) are a novel class of small noncoding RNA molecules that regulate gene expression by inducing degradation or translational inhibition of target mRNAs. There are more than 500 miRNA genes reported in the human genome, constituting one of the largest classes of regulatory genes. Increasing experimental evidence supports the idea of aberrant miRNA expression in cancer pathogenesis. We analyzed the pattern of miRNA expression in chronic lymphocytic leukemia (CLL) cells and our results showed a global reduction in miRNA expression levels in CLL cells associated to a consistent underexpression of miR-181a, let-7a and miR-30d. We observed overexpression of miR-155 and a set of five miRNAs that are differentially expressed between patients with different clinical outcomes. Five novel miRNA candidates cloned from leukemic cells are reported. Surprisingly, predicted mRNA targets for these novel miRNA revealed a high proportion of targets located in a small region of chromosome 1, which is frequently altered in human cancer. Additionally, several targets were shared by at least two of miRNA candidates. Predicted targets included several genes recently described as tumor suppressors. These data could afford new avenues for exploring innovative pathways in CLL biology and therapy.

Numerous plant species reproduce mainly by clonal growth, implying that levels of genetic variation may be comparatively low. In this study we describe the genetic and genotypic diversity within and between four Swedish populations of the clonal shrub lingonberry, Vaccinium vitis-idaea L. Two approaches were used to assess the amount and partitioning of variation: automated image analysis of leaf shape and random amplified polymorphic DNA (RAPD) analysis. Morphometric analyses, using moment invariants and elliptic Fourier coefficients, revealed that most of the variation could be attributed to within-population variation. With the use of 43 polymorphic RAPD markers, we were able to identify 29 different genotypes (i.e. putative clones) among 129 plants from two populations. The genotypic diversity (D: mean 0.84) and evenness (E: mean 0.81) were higher than the average for clonal plant species. Within-population gene diversity was similar to values reported in nonclonal plants, suggesting that sexual reproduction has played a significant role in these populations despite low levels of seedling recruitment in present-day populations. An analysis of molecular variance revealed that most of the variation (89.2%) resided within populations. Comparisons between the different suites of characters indicated a congruent pattern of partitions of diversity, particularly when comparing moment invariants and RAPDs. When comparing the ability of the two descriptor suites to assign the plants to the RAPD-defined clones, elliptic Fourier coefficients yielded the best result; a classification test correctly reassigned 96.9% and 98.1% of the plant material in the two respective populations.