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Mol Biol Evol:V60L突变增加皮肤癌易感性

  1. V60L突变
  2. 皮肤癌

来源:生物谷 2014-01-19 07:40

2014年1月18日讯 /生物谷BIOON/--当智人(Homo sapiens)离开非洲,不得不适应阳光较少的气候,其中负责调节黑色素合成的基因之一MC1R基因会发生突变,MC1R基因涉及皮肤的变色。这种皮肤变色允许更好地吸收维生素D,维生素D是生长所必需的,MC1R基因发生突变也增加了皮肤癌在成年期的风险。这种突变称为“V60L”,在地中海地区,如西班牙,葡萄牙,意大利和以色列人民中最常见。

Universitat Jaume I和Basque Country大学研究人员对西班牙不同地区的1000人进行研究,发现突变存在率约为10-20%。V60L突变多见于浅色头发和肤色的人中,在夏天容易晒黑。这种突变对于地中海地区气候是有利的,因为它有利于维生素D在冬季吸收,而冬季的紫外线辐射较低。

在夏季,辐射较大,容易变黑的皮肤色素沉着提供了一定的保障。然而,该研究还发现,有这种突变的人更大的皮肤癌易感性。这一发现可能会在医疗预防领域非常有用。该研究成果发表在Molecular Biology and Evolution杂志,揭示了MC1R基因(调节黑色素的合成),在撒哈拉以南非洲的欧亚人群中更加多样化。

研究发现:白皙的皮肤促进了合成维生素D,维生素在妊娠和成长的关键时期非常重要,在某种程度上,它的正常吸收对物种生存至关重要。然而,白皙的皮肤也与黑色素易感性增加瘤相关联。

然而,研究人员澄清,有许多因素而不仅是遗传对皮肤癌有影响,如过度暴露于紫外线的风险,遭受晒伤的童年等等。Basque Country大学和Universitat Jaume I之间的合作也有助于确定西班牙人口中这种基因遗传变异的存在。(生物谷Bioon.com)

 

Simultaneous purifying selection on the ancestral MC1R allele and positive selection on the melanoma-risk allele V60L in south Europeans

Conrado Martínez-Cadenas, et al.

In humans, the geographical apportionment of the coding diversity of the pigmentary locus melanocortin-1 receptor (MC1R) is, unusually, higher in Eurasians than in Africans. This atypical observation has been interpreted as the result of purifying selection due to functional constraint on MC1R in high UV-B radiation environments. By analyzing 3,142 human MC1R alleles from different regions of Spain in the context of additional haplotypic information from the 1000 Genomes (1000G) Project data, we show that purifying selection is also strong in southern Europe, but not so in northern Europe. Furthermore, we show that purifying and positive selection act simultaneously on MC1R. Thus, at least in Spain, regions at opposite ends of the incident UV-B radiation distribution show significantly different frequencies for the melanoma-risk allele V60L (a mutation also associated to red hair and fair skin and even blonde hair), with higher frequency of V60L at those regions of lower incident UV-B radiation. Besides, using the 1000G south European data, we show that the V60L haplogroup is also characterized by an extended haplotype homozygosity (EHH) pattern indicative of positive selection. We, thus, provide evidence for an adaptive value of human skin depigmentation in Europe and illustrate how an adaptive process can simultaneously help to maintain a disease-risk allele. In addition, our data support the hypothesis proposed by Jablonski and Chaplin (Human skin pigmentation as an adaptation to UVB radiation. Proc Natl Acad Sci U S A. 2010;107:8962–8968), which posits that habitation of middle latitudes involved the evolution of partially depigmented phenotypes that are still capable of suitable tanning.

 

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