- Details
- Parent Category: Chemistry
- Category: Medicinal
by Monya Baker
An analysis of when and where pluripotency factors bind indicate that c-Myc shuts down specialization and the remaining three turn on pluripotency
Scientists are still shocked that only a handful of introduced genes can turn a specialized cell's clock back so far that it behaves like an embryonic stem cell. Even with current established techniques, such reprogramming is a rare event, and researchers around the world are trying to figure out exactly how reprogramming can be triggered by genes for the pluripotency factors, which encode the transcription factors Oct4, Sox2, Klf4 and c-Myc. Publishing in Cell, researchers led by Kathrin Plath of the University of California, Los Angeles, show which genes are bound by the transcription factors in mouse embryonic stem cells, fully reprogrammed cells (induced pluripotent stem cells) and partially reprogrammed cells. The results, she believes, will help researchers find small molecules to replace the viral vectors currently used in the reprogramming process, which could result in more homogenous cells that are better suited for clinical applications.
- Details
- Parent Category: Chemistry
- Category: Organic
by Monya Baker
In the quest to switch one cell type to another, how far can tweaking transcription factors go? Thomas Graf, of the Centre for Genomic Regulation in Barcelona, is known for his work on converting one blood cell type to another. Monya Baker spoke to him about how this can be done — and why. How do you turn one cell type into another?
It's a matter of learning the changes in transcription factor networks that are instrumental in dictating cell fate. As cells develop away from each other, the transcription factor networks are more and more different, and we have to do more and more to turn one into the other.
Read more: Thomas Graf: Cellular Identity and Transdifferentiation
- Details
- Parent Category: Chemistry
- Category: Medicinal
by Monya Baker
G9a silences gene expression two ways
As embryonic stem cells differentiate, the pluripotency gene known as Oct4 goes on lockdown. In fact, the gates to gene expression are doublelocked: the gene-encoding DNA strands are wound up into a structure called heterochromatin, in which the DNA is complexed with histones and other proteins in such a way that it is inaccessible to the transcriptional machinery. Furthermore, gene-expression machinery is kept at bay by chemical modifications to the DNA that signals the start of a gene. New work published in Nature Structural and Molecular Biology1 shows not only that both of these modifications are regulated by a single master protein, the histone methyltransferase G9a, but that this enzyme apparently brings about the inactivation of many early embryonic genes.
- Details
- Parent Category: Chemistry
- Category: Medicinal
by Monya Baker
Making blood stem cell niches in vivo and in vitro
Two independent groups of researchers have made artificial versions of the stem cell niches where blood forms. Irving Weissman and colleagues at Stanford University in California found that with the right population of cells, bone can be made to grow in the kidney. What's more, that bone can recruit a vasculature and establish a blood-forming niche, complete with haematopoietic stem cells. This marks the first in vivo assay to assess the formation and maintenance of a blood-forming niche at a site outside its natural location, and the researchers were able to use the assay to assess the ability of various soluble proteins to help establish the niche1.
- Details
- Parent Category: Chemistry
- Category: Environmental
By William Booth
"I admit it does sound crazy," says Michael Wong of his idea to use gold to clean up toxic waste. Wong plans to combine gold with palladium—an even more precious metal—to treat polluted groundwater beneath waste dumps and contaminated factories and military sites. "It not only works faster [than current methods], but a hundred times faster," Wong says, "and I bet it will be cheaper too."
A golden detergent? Here is Wong's trick: he creates nanoparticles of gold. In his realm, the work product is measured not in carats but in atoms. A thimbleful of coffee-colored solution contains 100 trillion gold spheres—each only 15 atoms wide, or about the width of a virus. Upon every golden nanosphere, Wong and his team dust a dash of palladium atoms. Think of an infinitely small ice-cream scoop flecked with sprinkles.
- Details
- Parent Category: Chemistry
- Category: Environmental