Vitamin A Plays Major Roles
In the Human Body
Crucial For Key Physiological Functions Including:
Sperm Cell Formation and theDevelopment of the
Central Nervous System.
In a recently-published study mapping the structure
and function of the “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 retinoid group, is directly involved
in nuclear receptor signaling pathways, a key process
which activates genes in the human body.
“Our study found that Vitamin A itself is active for
activating nuclear receptor TR4,” said VARI
Researchers “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
now believe that Vitamin A may play more important
roles in human physiology than was previously believed.”
The study, published in the Journal of Biological
Chemistry, 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
nuclearreceptors 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
“Recent evidence has shown that orphan nuclear
receptors are required for many essential
physiological functions in the human body, and can
be used to help discover drug targets for human
diseases,” explained the research scientists.
“Additionally, the identification of ligands for nuclear
receptors usually leads to the discovery of new types
of therapeutic drugs for human diseases. A very
successful example is PPARs (peroxisome proliferator-
activated receptors), whose ligands are used for the
treatment of diabetes.” the research team in VARI’s
Laboratory of Structural Sciences, under the direction
of VARI Center for Structural Biology and Drug
Discovery used X-ray crystallography to determine
the structure of TR4′s ligand binding domain. They also
identified small molecules involved in TR4 transcription,
the synthesis of RNA using DNA as the blueprint, that
could serve as potential drug targets.
Van Andel Research Institute.
Journal Reference: The Orphan Nuclear Receptor TR4
Is a Vitamin A-activated Nuclear Receptor. Journal of
Biological Chemistry, 2010;
A recent study from Solae backs up these claims for
soy protein’s cholesterol lowering effect, but says the
mechanism behind benefits is ‘yet to be determined’.
The study published in the Journal of Clinical
Lipidology, suggests that soy protein lowers total
cholesterol and non-HDL cholesterol, in patients with
moderately high cholesterol levels, but said that a
mechanism for such benefits could not be determined.
Editor’s Note: This article is not intended to provide medical advice,
diagnosis or treatment.