c-Jun is a negative regulator of myelination
May 19, 2008
Schwann cell myelination depends on Krox-20/Egr2 and other promyelin transcription factors that are activated by axonal signals and control the generation of myelin-forming cells. Myelin-forming cells remain remarkably plastic and can revert to the immature phenotype, a process which is seen in injured nerves and demyelinating neuropathies.

In this research, authors report that c-Jun is an important regulator of this plasticity. At physiological levels, c-Jun inhibits myelin gene activation by Krox-20 or cyclic adenosine monophosphate. c-Jun also drives myelinating cells back to the immature state in transected nerves in vivo. Enforced c-Jun expression inhibits myelination in cocultures. Furthermore, c-Jun and Krox-20 show a cross-antagonistic functional relationship. c-Jun therefore negatively regulates the myelinating Schwann cell phenotype, representing a signal that functionally stands in opposition to the promyelin transcription factors. Negative regulation of myelination is likely to have significant implications for three areas of Schwann cell biology: the molecular analysis of plasticity, demyelinating pathologies, and the response of peripheral nerves to injury.
[Journal of Cell Biology]
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Gene regulating heart development in mammals identified
May 15, 2008
Researchers for the first time have successfully identified the factors responsible for the onset of heart formation in the mammalian embryo. Until now, no single mutation had been identified that was thought to be responsible for blocking proper development of the heart in mammalian embryos. The identification of these major developmental switches will allow researchers to unravel the fundamental mechanisms that define heart cell formation. As congenital heart defects are common in the US, understanding of these molecular pathways could be helpful in the development of effective treatments.
[Developmental Biology]
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Biology of fat storage in cells revealed
May 21, 2008
To identify novel genes involved in fat storage, the laboratories of Drs. Farese and Peter Walter (University of California, San Francisco) initiated a major discovery project, in which they used RNAi screens to individually inactivate all the genes in cells from fruit flies. Drs. Yi Guo and Tobias Walther, from the Farese and Walter laboratories, respectively, completed the initial survey, and identified the genes that have the most striking effects on fat storage. Surprisingly, they found that ~1.5% of all genes function in lipid-droplet formation and regulation. These genes proved to be determinants of the size, numbers, and physical locations of lipid droplets in cells. This research on biology of fat storage may have significant applications in obesity, diabetes, and heart disease.
[Nature]
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