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Archive - May 29, 2011

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E-Cadherin Is a Key Molecule for Stem Cell Pluripotency

Researchers at the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch and collaborating institutions have discovered what enables embryonic stem cells to differentiate into diverse cell types and thus to be pluripotent. This pluripotency depends on a specific molecule – E-cadherin – hitherto primarily known for its role in mediating cell-cell adhesion as a kind of “intracellular glue”. If E-cadherin is absent, the stem cells lose their pluripotency. The molecule also plays a crucial role in the reprogramming of somatic cells (body cells) into pluripotent stem cells. The work was reported online in EMBO Reports on May 27, 2011. Dr. Daniel Besser, Prof. Walter Birchmeier, and Torben Redmer from the MDC, a member of the Helmholtz Association, used mouse embryonic fibroblasts (MEFs) in their stem cell experiments. In a first step they showed that the pluripotency of these stem cells is directly associated with the cell-adhesion molecule E-cadherin. If E-cadherin is absent, the stem cells lose their pluripotency. In a second step, the researchers investigated what happens when somatic cells that normally neither have E-cadherin nor are pluripotent are reprogrammed into a pluripotent stem cell state. In this reprogramming technique, somatic cells are converted into induced pluripotent stem cells (iPSCs). This new technique may help researchers avoid the controversies that come with the use of human embryos to produce human embryonic stem cells for research purposes. The MDC researchers found that in contrast to the original cells, the new pluripotent cells derived from mouse connective tissue contained E-cadherin. “Thus, we have double proof that E-cadherin is directly associated with stem-cell pluripotency.

Low Vitamin D Levels a Risk Factor for MS in African Americans

In the first major study exploring the connection between vitamin D and multiple sclerosis in African Americans, a team of scientists at the University of California, San Francisco has discovered that vitamin D levels in the blood are lower in African Americans who have the disease, compared to African Americans who do not. “It seems relatively clear,” said Dr. Ari Green, who is the assistant director of the UCSF Multiple Sclerosis Center, director of the UCSF Neurodiagnostics Center and the senior author on the study. “Low vitamin D levels are a risk factor for developing multiple sclerosis.” Published online on May 24, 2011, in the journal Neurology, the results of the study are consistent with observations in Caucasian populations that link low vitamin D levels to having multiple sclerosis. However, the research could not explain why multiple sclerosis tends to be more severe in African Americans even though the disease is less common than in Caucasian populations. Earlier work by the same UCSF team established that African Americans tend to become disabled faster with multiple sclerosis, more frequently having to rely on canes and wheel chairs. “If we can understand why, we may be able to improve treatment for those patients,” said neurologist Dr. Bruce Cree, another author of the paper and one of the primary investigators. Vitamin D levels alone could not account for this apparent difference in severity, the study found. “There are likely other factors that drive the severity of the disease including genes and other environmental factors such as smoking,” said Dr, Jeffrey Gelfand, the first author on the study. Work is now underway to determine how genetic differences may affect the severity of multiple sclerosis.