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 have found.
Van Andel Research Institute (VARI) investigators came to the conclusion after mapping the structure and function of the so-called "orphan" nuclear receptor TR4.
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 Edward Zhou, one of the investigators.
"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," he added.
The study was published in the Journal of Biological Chemistry.