Idiosyncrasies of Viral Noncoding RNAs Provide Insights into Host Cell Biology.

Like their host cells, many viruses express noncoding RNAs (ncRNAs). Despite the technical challenge of ascribing function to ncRNAs, diverse biological roles for virally expressed ncRNAs have been described, including regulation of viral replication, modulation of host gene expression, host immune evasion, cellular survival, and cellular transformation. Insights into conserved interactions between viral ncRNAs and host cell machinery frequently lead to novel findings concerning host cell biology.

Splicing remodels the let-7 primary microRNA to facilitate Drosha processing in Caenorhabditis elegans.

MicroRNAs (miRNAs) are a class of small noncoding RNAs that use partial base-pairing to recognize and regulate the expression of messenger RNAs (mRNAs). Mature miRNAs arise from longer primary transcripts (pri-miRNAs) that are processed to a shorter hairpin precursor miRNA (pre-miRNA) by the Microprocessor complex. In Caenorhabditis elegans the primary let-7 (pri-let-7) transcript undergoes trans-splicing, where pri-let-7 is cleaved at a 3' splice site and the splice-leader-1 (SL1) sequence is appended at the 5' end.

A Heritable Recombination system for synthetic Darwinian evolution in yeast.

Genetic recombination is central to the generation of molecular diversity and enhancement of evolutionary fitness in living systems. Methods such as DNA shuffling that recapitulate this diversity mechanism in vitro are powerful tools for engineering biomolecules with useful new functions by directed evolution. Synthetic biology now brings demand for analogous technologies that enable the controlled recombination of beneficial mutations in living cells.

The miR-35-41 family of microRNAs regulates RNAi sensitivity in Caenorhabditis elegans.

RNA interference (RNAi) utilizes small interfering RNAs (siRNAs) to direct silencing of specific genes through transcriptional and post-transcriptional mechanisms. The siRNA guides can originate from exogenous (exo-RNAi) or natural endogenous (endo-RNAi) sources of double-stranded RNA (dsRNA). In Caenorhabditis elegans, inactivation of genes that function in the endo-RNAi pathway can result in enhanced silencing of genes targeted by siRNAs from exogenous sources, indicating cross-regulation between the pathways.

Let's make it happen: the role of let-7 microRNA in development.

Noncoding RNAs have emerged as an integral part of posttranscriptional gene regulation. Among that class of RNAs are the microRNAs (miRNAs), which posttranscriptionally regulate target mRNAs containing complementary sequences. The broad presence of miRNAs in lower eukaryotes, plants, and mammals highlights their importance throughout evolution.

Regulation of lin-4 miRNA expression, organismal growth and development by a conserved RNA binding protein in C. elegans.

Transcription and multiple processing steps are required to produce specific 22 nucleotide microRNAs (miRNAs) that can regulate the expression of target genes. In C. elegans, mature lin-4 miRNA accumulates at the end of the first larval stage to repress its direct targets lin-14 and lin-28, allowing the progression of several somatic cell types to later larval fates.