A team of Brooklyn College researchers has shattered a long-held belief that no direct pathway exists between material outside of a cell and the cell nucleus. (The cell is the smallest metabolically functional unit of life.)
It was already known that material outside of a cell can migrate into a cell. This occurs through processes known as endocytosis and phagocytosis, in which extracellular material is captured by a pinched-in segment of the cell membrane. This extracellular material then becomes trapped inside the resulting membrane-bound intracellular compartment, which is known as an endosome or phagosome.
It was also already known that material can migrate out of an endosome or phagosome and eventually enter the cell nucleus. But the Brooklyn College team has discovered that a phagosome and its contents can enter the cell's nucleus, where genetic information is stored and processed.
The team's discovery of the existence of direct pathways between extracellular material and cell nuclei will be published on August 10, 2007 in Cell Motility and the Cytoskeleton. The team was led by Ray Gavin and funded by the National Science Foundation (NSF).
Gavin says that these newly discovered direct pathways mean that "internalized material does not necessarily have to exit the phagosome before entering the nucleus." Therefore, his discovery means that "one less step is needed for extracellular material to get into the nucleus, and so it is far easier than previously thought for this material to get into the nucleus."
Eve Barak, an NSF program director, describes Gavin's discovery as "an amazing and potentially paradigm-changing observation," and predicts that it "will have an enormous impact on how scientists think about how cellular functions are regulated."
Gavin has only observed direct pathways from the extracellular environment to the nucleus in the one-celled protozoan Tetrahymena thermophila. But Gavin says
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National Science Foundation