A new method promises to cut through the stubborn problem of determining the precise targets of microRNAs – the tiny but powerful bits of nucleic acid that tweak gene expression to influence many aspects of health and human disease, from early development and aging to cancer, heart disease, and diabetes. 

Researchers using the new technique, called HITS-CLIP, showed that in a single experiment they could map the binding points of scores of different microRNAs throughout a genome in living mouse or human tissue.  The research by Howard Hughes Medical Institute investigator Robert Darnell and his colleagues Sung Wook Chi, Julie Zang, and Aldo Mele at The Rockefeller University was reported June 17, 2009, in an advanced online publication of the journal Nature. 

Although they have no sensory organs, bacteria can get a good idea about what's going on in their neighborhood and communicate with each other, mainly by secreting and taking in chemicals from their surrounding environment.  Even though there are millions of different kinds of bacteria with their own ways of sensing the world around them, Duke University bioengineers believe they have found a principle common to all of them. 

A new zinc finger protein, perhaps the first of many, silences integrated viruses

When induced pluripotent stem cells were first made, keen-eyed researchers rejoiced that the viruses required to reprogram the cells did not need to stay active indefinitely.  As the cells reprogram, the viruses are silenced.  That opened the door to reprogramming cells without genetic engineering, which meant that the resultant cells would be more applicable to drug screening and cell therapies. 

For the first time, human skin cells have been reprogrammed to pluripotency without requiring genetic elements to insert themselves into the reprogrammed cells.  Though so-called induced pluripotent stem cells promise to be as powerful as embryonic stem cells in their ability to differentiate into all cell types, standard techniques use viruses to insert multiple copies of reprogramming genes into the cells; this makes the cells less predictable, and it creates a higher risk of a cancerous growth.  As a result, many laboratories have been racing to publish techniques to reprogram cells without permanent genetic modification. 

Cells that behave like embryonic stem cells can be made from cultured skin, liver and stomach cells.  All techniques used so far require the addition of at least two pluripotency genes, which makes the cells much less attractive for use in cell therapy and drug screening.  Now, researchers led by Hans Schöler of the Max Planck Institute for Molecular Biomedicine in Münster, Germany, show that cells can be reprogrammed to pluripotency using just one of the standard four genes1. " With only one 'switch' — the gene Oct4 — we have turned adult somatic cells into stem cells that are very similar to embryonic stem cells", he explains. 

In 2006, stem cell scientists were shocked by the discovery that differentiated mouse cells can be reprogrammed to behave like embryonic stem cells.  All it took was the addition of a few pluripotency genes.  The following year, reports came that human cells can also be reprogrammed.  This year, a third species has joined the ranks.  A study published in Cell Stem Cell shows that a similar approach used for mouse and human cells can generate induced pluripotent stem cells from adult skin fibroblasts of the rhesus macaque.