By David N. Leff

A telephone linesman proceeds to his repair job in a telephone company vehicle. A public works crew arrives at the scene of a burst water main in a public works truck. It's most unlikely that the two would swap wheels — or expertise.

Equally improbable is the finding that a protein involved in wiring the developing fetal brain also has a hand in angiogenesis — the formation of blood vessels. In fact, the familiar term blood-brain barrier would seem to rule out such molecular moonlighting.

Yet a paper in the current issue of Cell, dated March 20, 1998, documents the convergence in the human body of angiogenesis and axonal guidance. Its title: "Neuropilin-1 is expressed by endothelial and tumor cells as an isoform-specific receptor for vascular endothelial growth factor." The article's senior author is surgeon Michael Klagsbrun of Harvard Medical School.

Neuropilin-1 is a receptor in the brain implicated in axonal guidance — sorting out how a zillion neurons navigate the developing fetal brain, to assemble the future adult nervous system.

But neuropilin-1 also turns out to be a receptor for vascular endothelial growth factor (VEGF), which honchos the architecture and proliferation of arteries, veins and capillaries. These blood vessels fuel the body — as well as malignant tumors — with oxygen and nutrients. (See BioWorld Today, Dec. 2, 1997.)

Two known VEGF receptors combine to do that growth factor's blood-vessel-building job. Neuropilin-1 was discovered by the Cell paper's first author, surgeon Shay Soker, in Klagsbrun's laboratory at Harvard-affiliated Boston Children's Hospital. This third VEGF receptor does a similar job of pattern-forming on growing brain cells by waving off other nerve cells from wandering into off-limits areas.

Breast and prostate cancers, the co-authors found, also make neuropilin in quantity, thus broadening VEGF's franchise in the body. Klagsburn suggested that besides its certified role in angiogenesis, VEGF helps tumor cells to prevent cell death.

Another speculation is that the third VEGF receptor may endow blood-vessel architecture, which is similar in most people, with the same exquisite structural design as brain cell patterning. *

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