Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, 210098, China.
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
Mol Biol Rep. 2021 Aug;48(8):6035-6046. doi: 10.1007/s11033-021-06606-4. Epub 2021 Aug 3.
Anti-Mullerian hormone receptor type II (Amhr2) is a key receptor of Amh signaling in regulating gonad development. The amhr2 gene has been identified in numerous species, including a few teleost fishes. However, the roles of Amhr2 in Amh signaling in fish are poorly studied.
In this study, an amhr2 homolog from obscure puffer (Takifugu obscurus) was identified, and its molecular characteristics were systematically analyzed. Expression analysis revealed that amhr2 was highly expressed in the gonads of adult pufferfish and significantly upregulated during sex differentiation. Significantly, a sex-linked SNP site was verified in obscure puffer amhr2. Females exhibited a homozygous genotype (C/C), while males possessed a heterozygous genotype (C/G), resulting in an amino acid variation (His/Asp384) in the kinase domain of Amhr2. Then, the functions of the different Amhr2 genotypes were further investigated. The male genotype protein (Amhr2) showed an enhanced ability to interact with the type I receptor (Bmpr1a) compared to the female genotype (Amhr2). The phosphorylation levels of Smads and activity of the target gene (id3) induced by the male genotype were also much higher than those induced by the female genotype. These results confirmed that the male genotype had an enhanced effect on the Amh signaling pathway compared with the female genotype.
This study provides direct experimental evidence for the roles of different Amhr2 genotypes in pufferfish and suggests that amhr2 is responsible for male sex differentiation in obscure puffer.
抗缪勒氏管激素受体 II 型（Amhr2）是调节性腺发育的 Amh 信号转导的关键受体。amhr2 基因已在许多物种中被鉴定出来，包括一些硬骨鱼。然而，Amhr2 在鱼类 Amh 信号转导中的作用研究甚少。
本研究从暗纹东方鲀（Takifugu obscurus）中鉴定出一个 amhr2 同源物，并对其分子特征进行了系统分析。表达分析显示，amhr2 在成年东方鲀的性腺中高度表达，并在性别分化过程中显著上调。值得注意的是，在暗纹东方鲀的 amhr2 中验证了一个性连锁 SNP 位点。雌性表现为纯合基因型（C/C），而雄性则具有杂合基因型（C/G），导致 Amhr2 激酶结构域中的一个氨基酸变异（His/Asp384）。然后，进一步研究了不同 Amhr2 基因型的功能。与女性基因型（Amhr2）相比，男性基因型蛋白（Amhr2）与 I 型受体（Bmpr1a）的相互作用能力增强。由男性基因型诱导的 Smads 磷酸化水平和靶基因（id3）的活性也明显高于由女性基因型诱导的水平。这些结果证实，与女性基因型相比，男性基因型对 Amh 信号通路具有更强的作用。
本研究为不同 Amhr2 基因型在河豚中的作用提供了直接的实验证据，并表明 amhr2 负责暗纹东方鲀的雄性性别分化。
