Fate in fly sensory organ precursor cells could explain human immun...( HOUSTON (June 21 2009) Notch signa...)

HOUSTON (June 21, 2009) Notch signaling helps determine the fate of a number of different cell types in a variety of organisms, including humans. In an article that appears in the current issue of Nature Cell Biology, researchers at Baylor College of Medicine report that a new finding about the Notch signaling pathway in sensory organ precursor cells in the fruit fly could explain the mystery behind an immunological disorder called Wiskott-Aldrich syndrome.

"This finding provides a model for how Wiskott Aldrich syndrome a form of selective immunodeficiency in children occurs," said Dr. Hugo Bellen (http://www.bcm.edu/db/db_fac-bellen.html), professor of molecular and human genetics and director of the Program in Developmental Biology at BCM. (http://www.bcm.edu/db/) He is also a Howard Hughes Medical Institute investigator.

It all begins with the Notch pathway, which controls cell fate.

In the fly peripheral nervous system, two daughter cells arise from a single sensory organ precursor mother cell. Among the daughter cells, Notch is activated in one and not in the other. This differential activation of signaling results in two different kinds of cells which arise from the same mother cell. Thus the fruit flies sensory organ precursor cell division has been used as a model to understand how Notch signaling is activated during asymmetric cell division.

In a screen of fruit fly mutants that have disrupted peripheral nervous system development, Akhila Rajan and An-chi Tien, two graduate students in Bellen's laboratory, identified a mutant with a cluster of neurons. This occurs when there is a problem in Notch signaling.

Ordinarily, the sensory organ progenitor cell uses the Notch pathway to specify the fate of two daughter cells called pIIa and pIIb, which arise from a single mother cell. The pIIa cells go on to be
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