Interaction of major coat color gene functions in mice as studied by chemical analysis of eumelanin and pheomelanin
Interaction of major coat color gene functions in mice as studied by chemical analysis of eumelanin and pheomelanin
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DOI：
10.1034/j.1600-0749.2001.140105.x
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发表时间：
2001-02-01
期刊：
影响因子：
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通讯作者：
Ito, S
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文献类型：
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作者：
Lamoreux, ML;Wakamatsu, K;Ito, S
黑素细胞产生两种化学上不同类型的黑色素，真黑素和褐黑素。这些色素可通过酸性高锰酸盐氧化或用异碘酸还原水解分别形成吡咯-2，3，5-三羧酸或氨基羟基苯丙氨酸进行定量分析。目前已克隆了约30个小鼠毛色基因，其中许多基因的功能已被阐明。然而，很少有人知道这些位点的相互作用的功能。在本研究中，我们使用同源小鼠来消除遗传变异，并分析了在一个或多个主要色素位点（即编码酪氨酸酶的白化病（C）位点、编码酪氨酸酶相关蛋白2的slaty（Slt）位点）突变的小鼠毛发中真黑素和褐黑素的含量（TRP 2，也称为多巴色素互变异构酶，DCT），编码TRP 1的棕色（B）基因座，编码黑素体银蛋白的银（Si）基因座，编码银蛋白信号蛋白（ASP）的银蛋白（A）基因座，编码黑皮质素-1的延伸（E）基因座。受体和桃花心木（Mg）基因座编码吸引。我们还测量了头发在热Soluene-350加水中溶解后的总黑色素含量。从2-3月龄的同类C57 BL/6 J小鼠剃毛。已知灰鼠（ch）等位基因编码酪氨酸酶，其活性约为野生型（C）的三分之一。栗鼠（c（ch）/c（ch））小鼠的表型是野生型或突变体在棕色和/或板色基因座表明，功能TRP 2和TRP 1是必要的，除了高水平的酪氨酸酶，一个完整的生产真黑素。灰鼠等位基因被发现减少数量的褐黑素在致命的黄色和隐性的黄色小鼠到不到五分之一的同类黄色小鼠是野生型的白化病基因座。这表明酪氨酸酶活性的降低与真黑素生成相比更深刻地影响了褐黑素生成。在板状基因座突变纯合的毛发含有5，6-二羟基吲哚-2-羧酸（DHICA）-贫黑色素，并且这种化学表型保留在棕色基因座和板状莲花突变的毛发中。来自棕色基因座突变而非板色基因座突变的小鼠的毛发不含DHICA贫乏的黑色素。这表明DHICA在真黑素中的比例由TRP 2决定，而不是由TRP 1决定。在slaty基因座（Slt（lt））的突变被发现有没有影响pheomelanogenesis，支持的作用TRP 2只在真黑素生成。银（si）位点的突变表现出类似于棕色的效应，即部分抑制真黑素的生成。桃花心木（mg）位点的突变部分抑制了致死黄（A（y））对褐黑质发生的影响，支持桃花心木在干扰agglutinin信号传导中的作用。这些结果表明，同源小鼠的双突变研究与黑色素的化学分析相结合，是有用的评估色素基因功能的相互作用。
Melanocytes produce two chemically distinct types of melanin pigments, eumelanin and pheomelanin. These pigments can be quantitatively analyzed by acidic permanganate oxidation or reductive hydrolysis with hydriodic acid to form pyrrole-2,3,5-tricarboxylic acid or aminohydroxyphenylalanine, respectively. About 30 coat color genes in mice have been cloned, and functions of many of those genes have been elucidated. However, little is known about the interacting functions of these loci. In this study, we used congenic mice to eliminate genetic variability, and analyzed eumelanin and pheomelanin contents of hairs from mice mutant at one or more of the major pigment loci, i.e,, the albino (C) locus that encodes tyrosinase, the slaty (Slt) locus that encodes tyrosinase-related protein 2 (TRP2 also known as dopachrome tautomerase, DCT), the brown (B) locus that encodes TRP1, the silver (Si) locus that encodes a melanosomal silver protein, the agouti (A) locus that encodes agouti signaling protein (ASP), the extension (E) locus that encodes melanocortin-1. receptor, and the mahogany (Mg) locus that encodes attractin. We also measured total melanin contents after solubilization of hairs in hot Soluene-350 plus water. Hairs were shaved from 2-3-month-old congenic C57BL/6J mice. The chinchilla ((ch)) allele is known to encode tyrosinase, whose activity is about one third that of wild type (C). Phenotypes of chinchilla (c(ch)/c(ch)) mice that are wild type or mutant at the brown and/or slaty loci indicate that functioning TRP2 and TRP1 are necessary, in addition to high levels of tyrosinase, for a full production of eumelanin. The chinchilla allele was found to reduce the amount of pheomelanin in lethal yellow and recessive yellow mice to less than one fifth of that in congenic yellow mice that were wild type at the albino locus. This indicates that reduction in tyrosinase activity affects pheomelanogenesis more profoundly compared with eumelanogenesis. Hairs homozygous for mutation at the slaty locus contain 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-poor melanin, and this chemical phenotype was retained in hairs that were mutant at both the brown locus and the slaty lotus. Hair from mice mutant at the brown locus, but not at the slaty locus, do not contain DHICA-poor melanin. This indicates that the proportion of DHICA in eumelanin is determined by TRP2, but not by TRP1. Mutation at the slaty locus (Slt(lt)) was found to have no effect on pheomelanogenesis, supporting a role of TRP2 only in eumelanogenesis. The mutation at silver (si) locus showed an effect similar to brown, a partial suppression of eumelanogenesis. The mutation at mahogany (mg) locus partially suppressed the effect of lethal yellow (A(y)) On pheomelanogenesis, supporting a role of mahogany in interfering with agouti signaling. These results show that combination of double mutation study of congenic mice with chemical analysis of melanins is useful in evaluating the interaction of pigment gene functions.