Neural stem cell differentiation factor discoveredJune 30, 2009Why neural stem cells divide and differentiate Neural stem cells represent the cellular backup of our brain. These cells are capable of self-renewal to form new stem cells or differentiate into neurons, astrocytes or oligodendrocytes. Astrocytes have supportive functions in the environment of neurons, while oligodendrocytes form the myelin layer around axons in order to accelerate neuronal signal transmission. But how does a neural stem cell „know" which way it is supposed to develop? On the molecular level receptors of the Notch family play a significant role in this process. So far, only stimulating extracellular ligands of Notch receptors had been described. Biochemists of Goethe University Medical School now describe a long time assumed but not yet identified soluble Notch inhibitor. Franfurt scientists led by Mirko Schmidt and Ivan Dikic reported in the renowned journal „Nature Cell Biology" that the secreted protein EGFL7 (Epidermal Growth Factor-like domain 7) is such an inhibitory factor. EGFL7 had already been known from its involvement in the development of blood vessels. „It was a surprise when we discovered that EGFL7 bound the extracellular domains of Notch receptors and competed with known Notch ligands" explains Ivan Dikic from the Institute of Biochemistry and CEF Institute in Frankfurt. Researchers analyzed the antagonistic effects of EGFL7 in adult neural stem cells. The self-renewal potential of these cells depends on an intact interaction of the ligand Jagged1 and its receptor Notch1. Addition of EGFL7 blocked the essential interaction and reduced the division of neural stem cells. At the same time, EGFL7 stimulated the differentiation of neural stem cells into neurons. „ It has been well defined that Notch signaling drives the formation of astrocytes from neural stem cells while it suppresses the formation of neurons and the maturation of oligodendrocytes" explains Mirko Schmidt at the Institute of Neurology. Inhibition of Notch signaling reverses the situation and more neural stem cells differentiate into neurons. This is exactly what happened upon the addition of EGFL7. In order to verify their findings in vivo, the researchers analyzed mouse brains and identified mature neurons as a source of EGFL7 in the adult brain. The distribution of these cells in the brain was biologically significant, as EGFL7 was absent from regions with high amounts of neural stem cells, e.g. the subventricular zone. „This way EGFL7 may promote the formation of new neurons" suggests Schmidt. The findings of Schmidt and Dikic offer a plethora of medical applications. Maturation of adult stem or precursor cells is significant for the development of multiple tissues, e.g. in the central nerve system or in the heart. Moreover, cancer stem cells have been described, which are important for the formation of tumors, especially in the human brain. EGFL7 might also be applied as a neuronal differentiation factor in ischemic insults or neurodegenerative diseases such as Alzheimer or Parkinson predict both researchers. Future work will unravel in which diseases EGFL7 can unfold its therapeutic potential. Goethe University Frankfurt |
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| Related Neural Stem Cells Current Events and Neural Stem Cells News Articles Scientists demonstrate link between genetic defect and brain changes in schizophrenia Researchers at the University of North Carolina at Chapel Hill School of Medicine have found that the 22q11 gene deletion - a mutation that confers the highest known genetic risk for schizophrenia - is associated with changes in the development of the brain that ultimately affect how its circuit elements are assembled. UNC study pinpoints gene controlling number of brain cells In populating the growing brain, neural stem cells must strike a delicate balance between two key processes - proliferation, in which the cells multiply to provide plenty of starting materials - and differentiation, in which those materials evolve into functioning neurons. Neural stem cells offer potential treatment for Alzheimer's disease UC Irvine scientists have shown for the first time that neural stem cells can rescue memory in mice with advanced Alzheimer's disease, raising hopes of a potential treatment for the leading cause of elderly dementia that afflicts 5.3 million people in the U.S. Blood stem cell growth factor reverses memory decline in mice A human growth factor that stimulates blood stem cells to proliferate in the bone marrow reverses memory impairment in mice genetically altered to develop Alzheimer's disease, researchers at the University of South Florida and James A. Haley Hospital found. Tumor suppressor gene in flies may provide insights for human brain tumors In the fruit fly's developing brain, stem cells called neuroblasts normally divide to create one self-renewing neuroblast and one cell that has a different fate. But neuroblast growth can sometimes spin out of control and become a brain tumor. Most common brain cancer may originate in neural stem cells University of Michigan scientists have found that a deficiency in a key tumor suppressor gene in the brain leads to the most common type of adult brain cancer. Human ES cells progress slowly in myelin's direction Scientists from the University of Wisconsin, USA, report in the journal Development the successful generation from human embryonic stem cells of a type of cell that can make myelin, a finding that opens up new possibilities for both basic and clinical research. Eye cells believed to be retinal stem cells are misidentified Cells isolated from the eye that many scientists believed were retinal stem cells are, in fact, normal adult cells, investigators at St. Jude Children's Research Hospital have found. Well-known enzyme is unexpected contributor to brain growth An enzyme researchers have studied for years because of its potential connections to cancer, diabetes, heart disease, hypertension and stroke, appears to have yet another major role to play: helping create and maintain the brain. Stem cells replace stroke-damaged tissue in rats Effective stem cell treatment for strokes has taken a significant step forward today (09 March) as scientists reveal how they have replaced stroke-damaged brain tissue in rats. More Neural Stem Cells Current Events and Neural Stem Cells News Articles |
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