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These are differentiating mouse embryonic stem cells (green = mesoderm progenitor cells, red = endoderm progenitor cells). The microRNAs identified in this study block endoderm formation, while enhancing mesoderm formation. An embryo is an amazing thing. From just one initial cell, an entire living, breathing body emerges, full of working cells and organs. It comes as no surprise that embryonic development is a very carefully orchestrated process—everything has to fall into the right place at the right time. Developmental and cell biologists study this very thing, unraveling the molecular cues that determine how we become human. "One of the first,...

The heart does have a limited ability to heal itself — and a genetic 'trick' can harness this. Can heart cells renew themselves, and can scientists help them do so? Two papers published online in Nature today suggest that heart muscle cells can make copies of themselves at a very low rate1, but that a genetic trick can prompt them to do a better job2. Those results give hope that hearts damaged by cardiovascular disease — which causes the deaths of almost 17 million people a year — could be coaxed to regenerate themselves. Heart muscle cannot renew itself very...

As anyone familiar with the phrase 'man-flu' will know women consider themselves to be the more robust side of the species when it comes to health and illness. Now new research, published in BioEssays, seems to support the idea. The research focuses on the role of MicroRNAs encoded on the X chromosome to explain why women have stronger immune systems to men and are less likely to develop cancer. The research, led by Dr Claude Libert from Ghent University in Belgium, focused on MicroRNA, tiny strains of ribonucleic acid which alongside DNA and proteins, make up the three major macromolecules...

Scientists identify an RNA molecule as a potential target for new Alzheimer's therapies Göttingen, September 23rd, 2011. Proteins are the molecular machines of the cell. They transport materials, cleave products or transmit signals – and for a long time, they have been a main focus of attention in molecular biology research. In the last two decades, however, another class of critically important molecules has emerged: small RNA molecules, including micro-RNAs. It is now well established that micro-RNAs play a key role in the regulation of cell function."A micro-RNA regulates the production of an estimated 300-400 proteins. This class of molecules...

Abstract Toll-like receptors (TLRs) in innate immune cells are the prime cellular sensors for microbial components. TLR activation leads to the production of proinflammatory mediators and thus TLR signaling must be properly regulated by various mechanisms to maintain homeostasis. TLR4-ligand lipopolysaccharide (LPS)-induced tolerance or cross-tolerance is one such mechanism, and it plays an important role in innate immunity. Tolerance is established and sustained by the activity of the microRNA miR-146a, which is known to target key elements of the myeloid differentiation factor 88 (MyD88) signaling pathway, including IL-1 receptor-associated kinase (IRAK1), IRAK2 and tumor-necrosis factor (TNF) receptor-associated factor 6 (TRAF6)....

Elevating a model in rats' brains blunted cocaine use Little things can make a big difference in the brain. Case in point: A tiny snippet of RNA may help guard cocaine-using rats against addiction to the drug, a new study shows. The minuscule molecular guard is a hairpin-shaped piece of RNA known as a microRNA. Raising levels of a microRNA called miR-212 in the brains of cocaine-using rats led the animals to take less of the drug than rats with normal microRNA levels, researchers report in the July 8 Nature. Similarly, blocking the microRNA’s action increased the rats’ cocaine use....

miRNA-145 represses Klf-4, Oct4 and Sox2, and is repressed by Oct4How pluripotency is controlled is one of biology's major puzzles. New research led by Kenneth Kosik of the University of California, Santa Barbara reveals not only a new piece in the puzzle but also how some major pieces fit together.A set of transcription factors — Klf4, Oct4 and Sox2 — is sufficient to reprogram specialized cells to pluripotency. As pluripotent cells take on a differentiated fate, these transcription factors disappear. Kosik found that one microRNA (miRNA) is able to repress all three of these proteins.Although these small RNA molecules can...

According to Darwinian theory, in the past we had a common ancestor with baboons, further back with bananas and still further with bacteria. This dogma has spread like a ‘meme’, which is a contagious idea that propagates in a similar way as a virus by infecting brains, according to inventor of the word, Richard Dawkins.1 In 2002, Roy Britten dispelled the first monkey meme that human and chimpanzee DNA sequences are 98.5% identical.2 He showed that when indelmutations were also taken into account, the difference suddenly became about 5%. The fact that chimpanzee genomes are about 10% larger than that...