Integrated Analysis of mRNA Expression, CpG Island Methylation, and Polymorphisms in the MITF Gene in Ducks (Anas platyrhynchos).

Ruiyi Lin,Jiahua Pan,Zhongbin Huang,Tianfang Xiao,Qiaohui Chen,Yuanxin Miao,Weimin Lin,Shiye Zhou,Mengwen Zhang

doi:10.1155/2019/8512467

Abstract

Microphthalmia-associated transcription factor (MITF) is a key regulator for the development and function of melanocytes in skin, eye, and plumage pigmentations. Thus, the MITF was selected as a candidate gene associated with plumage coloration in ducks. This study analyzed the mRNA expression, promoter methylation, and polymorphisms in the MITF gene in ducks with different plumage colors (Putian Black, Putian White, Liancheng White, and Longsheng Jade-green). No expression of the MITF melanin-specific isoform (MITF-M) was detected in white feather bulbs. By contrast, the mRNA expression levels of MITF-M were high in black feather bulbs. Bioinformatics analysis showed that two CpG islands were present in the promoter region of the MITF gene. The methylation level of the second CpG island was significantly lower in black feather bulbs than in white feather bulbs. However, the methylation level of the first CpG island was not different among the feather bulbs with various colors except Liancheng White feather bulbs. The methylation status of the whole CpG island significantly and negatively correlated with the mRNA expression of MITF-M (P < 0.05). Furthermore, four novel SNPs (single nucleotide polymorphisms) were identified in the 5′UTR, exon 4, intron 7, and intron 8 of the MITF gene. Allele T in g.39807T>G and allele G in g.40862G>A were the predominant alleles only found in Putian White, whereas the variant A allele in g.32813G>A exhibited a high allele frequency in Liancheng White. Collectively, these results contributed to the understanding of the function of the MITF gene in duck plumage coloration.

Highlights

Plumage color is an important characteristic of duck breed
In the process of melanin biosynthesis, tyrosinase, encoded by the TYR gene, is the rate-limiting enzyme affecting the production of melanin pigment [2] and determines which type of melanin can be synthesized [3]. e transcription of TYR family genes is activated by Microphthalmia-associated transcription factor (MITF) through binding to M-box in the upstream regulatory region [4]. e gene encoding MITF is a member of the Myc superfamily, which is part of the basic helix-loop-helix-leucine zipper family [5, 6]
Expression of TYR and MITF Genes in Duck Feather Bulbs. e TYR expression was detected to further confirm the feather bulbs with different colors. e expression pattern of the marker gene was consistent with the difference in plumage color

Summary

Introduction

Plumage color is an important characteristic of duck breed. Plumage color variation is mainly determined by two kinds of melanin, namely, eumelanin and pheomelanin [1]. In the process of melanin biosynthesis, tyrosinase, encoded by the TYR gene, is the rate-limiting enzyme affecting the production of melanin pigment [2] and determines which type of melanin can be synthesized [3]. E transcription of TYR family genes is activated by MITF (microphthalmia-associated transcription factor) through binding to M-box in the upstream regulatory region [4]. E gene encoding MITF is a member of the Myc superfamily, which is part of the basic helix-loop-helix-leucine zipper family [5, 6]. A high Mitf expression is observed in Silky Fowl, which is a natural mutant with hyperpigmentation in various internal tissues [8]

Methods

Results

Conclusion