Liu Ruiqi, Kinoshita Masato, Adolfi Mateus C, Schartl Manfred
Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany.
Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
Front Endocrinol (Lausanne). 2019 Apr 5;10:213. doi: 10.3389/fendo.2019.00213. eCollection 2019.
In mammals the melanocortin 4 receptor (Mc4r) signaling system has been mainly associated with the regulation of appetite and energy homeostasis. In fish of the genus (platyfish and swordtails) puberty onset is genetically determined by a single locus, which encodes the . Wild populations of are polymorphic for early and late-maturing individuals. Copy number variation of different alleles is responsible for the difference in puberty onset. To answer whether this is a special adaptation of the Mc4r signaling system in the lineage of or a more widely conserved mechanism in teleosts, we studied the role of Mc4r in reproductive biology of medaka (), a close relative to and a well-established model to study gonadal development. To understand the potential role of Mc4r in medaka, we characterized the major features of the Mc4r signaling system (). In medaka, all these genes are expressed before hatching. In adults, they are mainly expressed in the brain. The transcript of the receptor accessory protein co-localizes with in the hypothalamus in adult brains indicating a conserved function of modulating Mc4r signaling. Comparing growth and puberty between wild-type and knockout medaka revealed that absence of Mc4r does not change puberty timing but significantly delays hatching. Embryonic development of knockout animals is retarded compared to wild-types. In conclusion, the Mc4r system in medaka is involved in regulation of growth rather than puberty.
在哺乳动物中，黑皮质素4受体（Mc4r）信号系统主要与食欲调节和能量稳态相关。在剑尾鱼属鱼类（孔雀鱼和剑尾鱼）中，青春期开始由一个单一位点基因决定，该基因编码[具体内容缺失]。剑尾鱼属的野生种群在早熟和晚熟个体方面存在多态性。不同[具体内容缺失]等位基因的拷贝数变异导致青春期开始时间的差异。为了回答这是剑尾鱼属谱系中Mc4r信号系统的特殊适应性，还是硬骨鱼中更广泛保守的机制，我们研究了Mc4r在青鳉（一种与剑尾鱼亲缘关系密切且是研究性腺发育的成熟模型）生殖生物学中的作用。为了了解Mc4r在青鳉中的潜在作用，我们对Mc4r信号系统的主要特征进行了表征（[具体内容缺失]）。在青鳉中，所有这些基因在孵化前就已表达。在成体中，它们主要在大脑中表达。受体辅助蛋白[具体内容缺失]的转录本在成体大脑的下丘脑中与[具体内容缺失]共定位，表明其在调节Mc4r信号方面具有保守功能。比较野生型和Mc4r基因敲除青鳉的生长和青春期发现，Mc4r缺失不会改变青春期时间，但会显著延迟孵化。与野生型相比，基因敲除动物的胚胎发育受到阻碍。总之，青鳉中的Mc4r系统参与生长调节而非青春期调节。
