Hsa-miR-34b is a plasma-stable microRNA that is elevated in pre-manifest Huntington's disease.

Huntington's disease (HD) is a devastating, neurodegenerative condition, which lacks effective treatment. Normal Huntingtin (HTT) and mutant Huntingtin (mHTT) are expressed in multiple tissues and can alter transcription of microRNAs (miRs). Importantly, miRs are present in a bio-stable form in human peripheral blood plasma and have recently been shown to be useful biomarkers in other diseases. We therefore sought to identify potential miR biomarkers of HD that are present in, and have functional consequences for, neuronal and non-neuronal tissues. In a cell line over-expressing mHTT-Exon-1, miR microarray analysis was used to identify candidate miRs. We then examined their presence and bio-stability in control and HD plasma. We found that miR-34b is significantly elevated in response to mHTT-Exon-1, and its blockade alters the toxicity of mHTT-Exon-1 in vitro. We also show that miR-34b is detectable in plasma from small input volumes and is insensitive to freeze-thaw-induced RNA degradation. Interestingly, miR-34b is significantly elevated in plasma from HD gene carriers prior to symptom onset. This is the first study suggesting that plasma miRs might be used as biomarkers for HD.

Conserved long noncoding RNAs transcriptionally regulated by Oct4 and Nanog modulate pluripotency in mouse embryonic stem cells.

The genetic networks controlling stem cell identity are the focus of intense interest, due to their obvious therapeutic potential as well as exceptional relevance to models of early development. Genome-wide mapping of transcriptional networks in mouse embryonic stem cells (mESCs) reveals that many endogenous noncoding RNA molecules, including long noncoding RNAs (lncRNAs), may play a role in controlling the pluripotent state. We performed a genome-wide screen that combined full-length mESC transcriptome genomic mapping data with chromatin immunoprecipitation genomic location maps of the key mESC transcription factors Oct4 and Nanog. We henceforth identified four mESC-expressed, conserved lncRNA-encoding genes residing proximally to active genomic binding sites of Oct4 and Nanog. Accordingly, these four genes have potential roles in pluripotency. We show that two of these lncRNAs, AK028326 (Oct4-activated) and AK141205 (Nanog-repressed), are direct targets of Oct4 and Nanog. Most importantly, we demonstrate that these lncRNAs are not merely controlled by mESC transcription factors, but that they themselves regulate developmental state: knockdown and overexpression of these transcripts lead to robust changes in Oct4 and Nanog mRNA levels, in addition to alterations in cellular lineage-specific gene expression and in the pluripotency of mESCs. We further characterize AK028326 as a co-activator of Oct4 in a regulatory feedback loop. These results for the first time implicate lncRNAs in the modulation of mESC pluripotency and expand the established mESC regulatory network model to include functional lncRNAs directly controlled by key mESC transcription factors.