BACKGROUND Dicer, an RNAse III endonuclease critical for processing of pre-microRNAs (miRNAs) into mature 22-nucleotide miRNAs, has proven a useful target to dissect the significance of miRNAs biogenesis in mammalian biology. METHODS AND RESULTS To circumvent the embryonic lethality associated with germline null mutations for Dicer, we triggered conditional Dicer loss through the use of a tam...

MicroRNAs (miRNAs) are small RNAs that control gene expression through silencing of target mRNAs. Mature miRNAs are processed from primary miRNA transcripts by the endonuclease activity of the DICER-LIKE1 (DCL1) protein complex. Mechanisms exist that allow the DCL1 complex to precisely excise the miRNA from its precursor. Our understanding of miRNA biogenesis, particularly its intersection with...

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at the transcriptional or posttranscriptional level. Many miRNAs are found to play a significant role in cancer development either as tumor suppressor genes or as oncogenes. Examination of tumor-specific miRNA expression profiles in diverse cancers has revealed widespread deregulation of these molecules, whose loss and o...

MicroRNAs (miRNAs) are single-stranded, non-coding RNA molecules that regulate gene expression post-transcriptionally by binding to messenger RNAs. miRNAs important regulators of expression, and their dysregulation is implicated in many human canine diseases. Most cancers tested date have been shown express altered miRNA levels, which indicates potential importance the oncogenic process. Based ...

Kaposi's sarcoma-associated herpesvirus (KSHV), the causative agent of Kaposi's sarcoma, encodes 25 mature viral miRNAs. MCP-1-induced protein-1 (MCPIP1), a critical regulator of immune homeostasis, has been shown to suppress miRNA biosynthesis via cleavage of precursor miRNAs through its RNase domain. We demonstrate that MCPIP1 can directly cleave KSHV and EBV precursor miRNAs and that MCPIP1 ...

MicroRNAs (miRNAs) are 18- to 24-nt RNA molecules that regulate messenger RNAs (mRNAs). Posttranscriptional mechanisms regulate miRNA abundance during development as well as in cancer cells where miRNAs frequently exhibit dysregulated expression. The molecular mechanisms that govern the global efficiency of miRNA biogenesis in these settings remain incompletely understood, and experimental syst...

Stringent regulation of biochemical signalling pathways involves feedback and feedforward loops, which underlie robust cellular responses to external stimuli. Regulation occurs in all horizontal layers of signalling networks, primarily by proteins that mediate internalization of receptor-ligand complexes, dephosphorylation of kinases and their substrates, as well as transcriptional repression. ...

MicroRNAs (miRNAs) originate from stem-loop-containing precursors (pre-miRNAs, pri-miRNAs) and mature by means of the Drosha and Dicer endonucleases and their associated factors. The let-7 miRNAs have prominent roles in developmental differentiation and in regulating cell proliferation. In cancer, the tumor suppressor function of let-7 is abrogated by overexpression of Lin28, one of several RNA...

Encoded by the genome of most eukaryotes examined so far, microRNAs (miRNAs) are small approximately 21-nucleotide (nt) noncoding RNAs (ncRNAs) derived from a biosynthetic cascade involving sequential processing steps executed by the ribonucleases (RNases) III Drosha and Dicer. Following their recent identification, miRNAs have rapidly taken the center stage as key regulators of gene expression...