Grand Rapids, Mich. (March 17, 2011) In a recently-published study mapping the structure and function of the so-called "orphan" nuclear receptor TR4, Van Andel Research Institute (VARI) investigators suggest that Vitamin A may play a more direct role than was previously known in certain physiological functions including sperm cell formation and the development of the central nervous system.
Scientists had previously determined that Vitamin A derivatives such as retinal and the retinoic acids are involved in physiological functions in the human body. But there has been little direct evidence to show that Vitamin A, or retinol, the most common dietary form of the vitamin and the parental compound of the retinoid group, is directly involved in nuclear receptor signaling pathways a process which activates genes in the human body.
"Our study found that Vitamin A itself is active for activating nuclear receptor TR4," said VARI Research Scientist Edward Zhou, Ph.D. "Because TR4 plays roles in sperm cell production, lipid and lipoprotein regulation, the development of the central nervous system, and the regulation of hemoglobin production in the embryo, we can imagine that Vitamin A may play more important roles in human physiology than was previously believed."
The study, published in the Journal of Biological Chemistry, was named by the journal as a "Paper of the Week," indicating that the study is in the top 1 percent of published papers in terms of significance and overall importance. About 50 to 100 such studies are selected from the more than 6,600 published by the journal each year.
Nuclear receptors activate genes in important biological processes in the human body. Orphan nuclear receptors are a group of nuclear receptors whose ligands, or the substance to which receptors bind, have not yet been identified, and whose physiological functions have not been very well investigated.
"Recent evidence has show
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Van Andel Research Institute