Protein Critical for Development of Body Identified

Researchers at the Salk Institute have identified a critical protein involved in early development of the human body, raising the possibility of at least a partial answer to one of the most profound puzzles of human biology.

The protein appears to play a central role in prompting cells in an embryo to differentiate and develop into limbs and organs. The new research, to be published this month in the British scientific journal Nature, appears to confirm theories explaining early development.

“It should provide some fundamental principles about development itself, about the process of how an organism forms,” said Ronald Evans, the researcher who runs the lab where the work was done.

“That is important not only to address basic questions in biology,” Evans added. “It has long been believed that an understanding of these basic rules will shed light on a variety of human diseases and how they came about.”

The team’s findings concern the chemical signals that are believed to direct the location and role of newly formed cells, guiding the formation of limbs and the function of such things as liver and brain cells.

Until recently, little was known about those signals--what they are and how they operate. Then earlier this year, researchers at Harvard identified the first so-called morphogen, a substance emitted from a central point to influence the development of cells.

The substance the Harvard group identified was Vitamin A or its metabolic derivative, retinoic acid. Its identification represented the first time a morphogen had been identified in a vertebrate.

Now, the team at Salk has identified that morphogen’s so-called receptor, a protein whose activity is triggered by retinoic acid. The team’s identification of the retinoic acid receptor helps explain how that morphogen works.

“The identification of a receptor for the morphogen completes the theory,” Evans said.

In a telephone interview Wednesday, Evans said the molecule also may be associated with certain types of cancers, including liver tumors. For that reason, its identification offers new insight into that disease.

The retinoic acid receptor is the most recent in a growing number of receptors identified in the laboratory of Evans, a professor at the biological research institute in La Jolla and an investigator of the Howard Hughes Medical Institute.