Regulatory Role of Retinoic Acid in Male Pregnancy of the Seahorse

• Main Authors: Chunyan Li, Yongxin Li, Geng Qin, Zelin Chen, Meng Qu, Bo Zhang, Xue Han, Xin Wang, Pei-yuan Qian, Qiang Lin
• Format: Article
• Language: English
• Published: Elsevier 2020-11-01
• Series: The Innovation
• Subjects: seahorse; male pregnancy; brood pouch; integrative omics; retinoic acid; antioxidant defense
• Online Access: http://www.sciencedirect.com/science/article/pii/S2666675820300552

Summary: Seahorses epitomize the exuberance of evolution. They have the unique characteristic of male pregnancy, which includes the carrying of many embryos in a brood pouch that incubates and nourishes the embryos, similar to the mammalian placenta. However, the regulatory networks underlying brood pouch formation and pregnancy remain largely unknown. In this study, comparative transcriptomic and metabolomic profiling on the lined seahorse Hippocampus erectus, with unformed, newly formed, and pregnant brood pouches identified a total of 141 and 2,533 differentially expressed genes together with 73 and 121 significantly differential metabolites related to brood pouch formation and pregnancy, respectively. Specifically, integrative omics analysis revealed that retinoic acid (RA) synthesis and signaling pathway played essential roles in the formation of the brood pouch and pregnancy. RA might function upstream of testosterone and progesterone, thereby directly influencing brood pouch formation by regulating the expression of fshr and cyp7a1. Our results also revealed that RA regulates antioxidant defenses, particularly during male pregnancy. Alternatively, pregnancy caused a consistent decrease in RA, canthaxanthin, astaxanthin, and glutathione synthetase, and an increase in susceptibility to oxidative stress, which may balance brood pouch development and reproduction in seahorses and pave the way to successful gestation.