Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
Biomed Res Int. 2018 Jun 4;2018:8120263. doi: 10.1155/2018/8120263. eCollection 2018.
Hypocretin system is composed of hypocretins (hcrts) and their receptors (hcrtrs), which has multiple vital functions. Hypocretins work via hypocretin receptors and it is reported that functional differentiation occurred in hcrtrs. It is necessary to figure out the evolution process of hypocretin receptors. In our study, we adopt a comprehensive approach and various bioinformatics tools to analyse the evolution process of HCRTR gene family. It turns out that the second round of whole genome duplication in early vertebrate ancestry and the independent round in fish ancestry may contribute to the diversity of HCRTR gene family. HCRTR1 of fishes and mammals are not the same receptor, which means that there are three members in the family. HCRTR2 is proved to be the most ancient one in HCRTR gene family. After duplication events, the structure of HCRTR1 diverged from HCRTR2 owing to relaxed selective pressure. Negative selection is the predominant evolutionary force acting on the HCRTR gene family but HCRTR1 of mammals is found to be subjected to positive selection. Our study gains insight into the molecular evolution process of HCRTR gene family, which contributes to the further study of the system.
下丘脑分泌素系统由下丘脑分泌素（hcrts）及其受体（hcrtrs）组成，具有多种重要功能。下丘脑分泌素通过下丘脑分泌素受体发挥作用，据报道，hcrtrs 发生了功能分化。有必要弄清楚下丘脑分泌素受体的进化过程。在我们的研究中，我们采用综合方法和各种生物信息学工具来分析 HCRTR 基因家族的进化过程。结果表明，早期脊椎动物祖先的第二轮全基因组复制和鱼类祖先的独立轮次可能导致了 HCRTR 基因家族的多样性。鱼类和哺乳动物的 HCRTR1 不是相同的受体，这意味着该家族有三个成员。HCRTR2 被证明是 HCRTR 基因家族中最古老的一个。在复制事件之后，由于选择压力的放松，HCRTR1 的结构从 HCRTR2 中分化出来。负选择是作用于 HCRTR 基因家族的主要进化力量，但哺乳动物的 HCRTR1 被发现受到正选择的影响。我们的研究深入了解了 HCRTR 基因家族的分子进化过程，这有助于对该系统的进一步研究。
