Chromatin Context Tip(60)s the Transcriptional Balance in ESCsNovember 12, 2008Unfortunately, the KISS principle (‘keep it simple, stupid’) doesn’t apply to chromatin. Although we’d like to think that certain histone modifications are always “good” for gene transcription and others are invariably “bad,” Barbara Panning and co-workers at the University of California San Francisco have found that in embryonic stem cells (ESCs), the transcriptional outcome of […]
Silencing Is in the AirNovember 12, 2008Everywhere you look, be it Science or Nature, US Weekly (OK, not quite), silencing by ncRNAs is making headlines. But the targets and mechanisms of this silencing are not always clear. A recent report by Peter Fraser and co-workers at The Babraham Institute (UK) and several other universities and centers in Japan and Europe has […]
Epigenetic Changes in a Hard-to-Treat Childhood CancerNovember 5, 2008A very difficult-to-treat childhood leukemia may benefit from the discovery of a small but potent epigenetic change that launches the cancer but could potentially be reversed relatively easily, preventing cancer-promoting genes from being turned on. Children with the subtype of acute lymphoblastic leukemia (ALL) known as MLL-AF4 have a cure rate of just under 50 […]
miRNA Silences Transcription of a Neighboring GeneOctober 22, 2008Like a conscientious librarian, miRNA can’t seem to resist saying “Shhhh!” whenever the opportunity arises, whether in post-transcriptional or, as a new study suggests, in transcriptional silencing of genes. Although miRNAs were initially thought to suppress gene expression primarily through translational inhibition, recent evidence suggests additional roles for miRNAs in regulating gene expression in the […]
Mutant HistonesOctober 15, 2008Over the years mutants like E.T., the Hulk, Yoda, and the X-Men to name a few, have all left a lasting impression in our lives. That’s why when a group of John’s Hopkins researchers, led by Jef Boeke, produced a library of synthetic histone H3 and H4 mutants to probe the function of each residue […]
Intron-Encoded miRNA Sidekick to the RescueOctober 15, 2008Every great star has a sidekick who sometimes threatens to steal the show: Batman had Robin, Sherlock Holmes had Dr. Watson, and Hillary had Bill. Likewise, some proteins appear to have an intron-encoded miRNA sidekick that neutralizes the “bad guys” so that the protein can effectively perform its cellular function, as demonstrated in a recent […]
Good Twin/Bad Twin: Is Epigenetics to Blame?October 13, 2008The Evil Twin is a staple of the soap opera genre—you know, the long-lost, villainous sister who kidnaps her virtuous twin and assumes her life, only to be discovered years later when the Good Twin escapes from imprisonment on an alien-inhabited desert isle. But in real life, how can identical twins with the same genes […]
ncRNAs Pave the Way for Chromatin RemodelingOctober 6, 2008Researchers have been puzzled by the discovery of several-kilobase-long, polyadenylated transcripts that overlap functional coding regions but do not themselves encode proteins. A recent Nature paper by Kouji Hirota, Kunihiro Ohta, and co-workers at the RIKEN Advanced Science Institute (Japan), the University of Tokyo, and Boston College indicates that some of these ncRNAs are transcriptional […]
RNA-Directed DNA deMethylation: An Undiscovered Country in the RNA World?October 1, 2008Let’s face it: it’s an RNA world. In addition to RNA’s many genetic, catalytic, and structural roles, the discovery of small non-coding RNAs has unveiled an entire continent of epigenetic functions. Small RNAs act in processes such as mRNA destruction, translational inhibition, and DNA methylation. Now it appears that, at least in plants, small RNAs […]
How’s That For Gratitude: let-7 miRNA Targets Dicer’s Coding SequenceSeptember 30, 2008Recent evidence has shown that the let-7 miRNA bites the hand that feeds it . . . and in an unconventional way. By searching for short sequences conserved at the nucleotide level in the coding regions of 17 species, Hilary Coller and co-workers at Princeton University identified three let-7 target sites within the coding sequence […]