期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2019
卷号：116
期号：49
页码：24527-24532
DOI：10.1073/pnas.1915442116
出版社：The National Academy of Sciences of the United States of America
摘要：Vitamin D is produced in the skin following exposure to sunlight. Ultraviolet (UV) B (UVB, 280–310 nm) results in isomerization of 7-dehydrocholesterol to previtamin D that spontaneously isomerizes to vitamin D. This pool of skin-derived vitamin D is the major source of vitamin D for animals. However, the mechanisms by which it becomes available remain undefined. It has been assumed that cutaneous vitamin D is transported into the circulation by vitamin D binding protein (DBP), but experimental evidence is lacking. To determine whether cutaneous vitamin D is transported by DBP, we utilized DBP −/− mice that were made vitamin D-deficient. These animals lack measurable 25(OH)D in blood and are hypocalcemic. As controls, DBP +/+ animals were vitamin D depleted and made equally hypocalcemic. UV irradiation of DBP +/+ animals restored serum calcium and serum 25(OH)D while the same treatment of DBP −/− animals failed to show either a serum calcium or 25(OH)D response despite having normal vitamin D production in skin. Intravenous injection of small amounts of recombinant DBP to the vitamin D-deficient DBP −/− mice restored the response to UV light. These results demonstrate a requirement for DBP to utilize cutaneously produced vitamin D..
关键词：vitamin D ; vitamin D binding protein ; UV light
