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Cholecalciferol is a form of vitamin D which is naturally synthesized in skin and functions as a pro-hormone, being converted to calcitriol. This is important for maintaining calcium levels and promoting bone health and development. [4] As a medication, cholecalciferol may be taken as a dietary supplement to prevent or to treat vitamin D ...
7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is photochemically converted to vitamin D 3 in the skin, therefore functioning as provitamin-D 3. The presence of this compound in human skin enables humans to manufacture vitamin D 3 (cholecalciferol).
Calcifediol is further hydroxylated by the kidneys and certain immune cells to form calcitriol (1,25-dihydroxycholecalciferol; 1,25(OH) 2 D), the biologically active form of vitamin D. [3] Calcitriol attaches to vitamin D receptors, which are nuclear receptors found in various tissues throughout the body.
Sterols and related compounds play essential roles in the physiology of eukaryotic organisms, and are essential for normal physiology of plants, animals, and fungi. [8] For example, cholesterol forms part of the cellular membrane in animals, where it affects the cell membrane's fluidity and serves as secondary messenger in developmental signaling.
In humans, the vitamin D receptor is encoded by the VDR gene located on chromosome 12q13.11. [7] VDR is expressed in most tissues of the body, and regulates transcription of genes involved in intestinal and renal transport of calcium and other minerals. [8] Glucocorticoids decrease VDR expression. [8] Many types of immune cells also express VDR ...
Calcitriol is a hormone and the active form of vitamin D, normally made in the kidney. [8] [9] [10] It is also known as 1,25-dihydroxycholecalciferol.It binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. [11]
Cholesterol is the principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. [3] [4]Cholesterol is biosynthesized by all animal cells [citation needed] and is an essential structural and signaling component of animal cell membranes.
Calcifediol is the precursor for calcitriol, the active form of vitamin D. [3] [4] It is synthesized in the liver, by hydroxylation of cholecalciferol (vitamin D 3) at the 25-position. [3] This enzymatic 25-hydroxylase reaction is mostly due to the actions of CYP2R1 , present in microsomes , although other enzymes such as mitochondrial CYP27A1 ...