Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2011) 26 S21.1

ECE2011 Symposia Vitamin D, pregnancy and development (3 abstracts)

Evolutionary perspective in vitamin D and its receptor VDR

Zeev Hochberg


Rambam Medical Centre, Haifa, Israel.


Vitamin D is photosynthesized in all forms of life from the phytoplankton 750 mya. Evolutionary pressures due to variation in climate play an important role in shaping phenotypic variation and influence variation in phenotypes. Migration out-of-Africa and change of living latitude placed human vit D as part of an evolutionary complex that adapted hominids to changing u.v. radiation. The ‘vit D hypothesis’ to explain skin pigmentation is based on the observation that the skin color follows a clinical distribution: the darkest populations inhabit the equatorial and tropical belt; the most pale-skinned the regions above 50°N; and those of intermediate pigmentation the middle latitudes. Exposure to u.v. light has to balance the need for UVB for vit D photosynthesis and damage by u.v. for folic acid generation. This balance is maintained by melanism, which determines skin color, reflecting a compromise solution to the conflicting physiological need for vit D and the detrimental effect of u.v. on folic acid generation. A multi-stage genome-wide association study of natural hair color identified several loci highly associated with hair color. But the strongest determinant of skin color remains MC1R. I propose that the VDR gene is epistatic with skin color-determining genes for the phenotype of fitness; both MC1R and the VDR are strongly implicated in immune system regulation, with obvious fitness consequences. VDR may be the original nuclear receptor gene, functioning initially as pregnane X receptors and constitutive androstane receptors, to induce P450 enzymes for xenobiotic detoxification. The broad abundance of the VDR may be also related to the multitude of recent reports claiming a role for vit D in cell differentiation and proliferation, immune function, muscle strength, blood pressure control and more.

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