title: Vitamin D3: an ever green molecule.
abstract: Vitamin D3 is a key regulator of vertebrates homeostasis. It is synthesized from the precursor 7-dehydrocholesterol upon UVB exposure in the skin and then hydrolyzed in the liver in position 25, to be finally converted into its active form, 1,25-dihydroxyvitamin D (1,25(OH)2D or calcitriol), in the kidneys. The biological activity of this molecule depends on its binding to the nuclear receptor VDR, which binds VDRE once complexed with RXR-alpha. Despite being present in different types of food, the best way to assume it at physiological levels remains the exposure to UVB radiation at certain hours of the day and at particular angles of the Earth's crust. There is plenty of evidence that altered levels of vitamin D3 are associated with pathological conditions, such as osteoporosis, cancer, immunological and infectious diseases. In this review, we discuss vitamin D3 metabolism, its role in several diseases and the link between vitamin D3 and immune cells.
authors.affiliation: Department of Biomedical Sciences, University of Catania, Catania, Italy. miky.dirosa@hotmail.it
authors.forename: Michele
authors.initials: M
authors.lastname: Di Rosa
authors.forename: Lucia
authors.initials: L
authors.lastname: Malaguarnera
authors.forename: Anna
authors.initials: A
authors.lastname: Nicolosi
authors.forename: Cristina
authors.initials: C
authors.lastname: Sanfilippo
authors.forename: Clorinda
authors.initials: C
authors.lastname: Mazzarino
authors.forename: Piero
authors.initials: P
authors.lastname: Pavone
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Berretta
authors.forename: Stefano
authors.initials: S
authors.lastname: Cosentino
authors.forename: Bruno
authors.initials: B
authors.lastname: Cacopardo
authors.forename: Marilia Rita
authors.initials: MR
authors.lastname: Pinzone
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Nunnari
mesh_terms: D000818:Animals; D002762:Cholecalciferol / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007239:Infections / Q000378:metabolism; D009369:Neoplasms / Q000378:metabolism; D010024:Osteoporosis / Q000378:metabolism; D012867:Skin / Q000276:immunology / Q000378:metabolism
chemical_list: D002762:Cholecalciferol