The CXC Chemokine Receptors in Four-Eyed Sleeper (<i>Bostrychus sinensis</i>) and Their Involvement in Responding to Skin Injury

• Main Authors: Mengdan Dong, Hong Zhang, Chengyu Mo, Wenjing Li, Wanwan Zhang, Kuntong Jia, Wei Liu, Meisheng Yi
• Format: Article
• Language: English
• Published: MDPI AG 2021-09-01
• Series: International Journal of Molecular Sciences
• Subjects: four-eyed sleeper; CXC chemokine receptors; CXCR6; skin injury
• Online Access: https://www.mdpi.com/1422-0067/22/18/10022
• ISSN: 1661-6596; 1422-0067

CXC Chemokine signaling plays an important role in wound healing. The four-eyed sleeper (<i>Bostrychus sinensis</i>) is a commercially important marine fish, which is prone to suffer skin ulceration at high temperature seasons, leading to mass mortality of fish in aquaculture farms. The genetic background related to skin ulceration and wound healing has remained unknown in this fish. Herein, we identified 10 differentially expressed <i>Bostrychus sinensis</i> CXC chemokine receptors (<i>BsCXCRs</i>) in skin ulcerated fish by de novo transcriptome sequencing. The transcripts of these <i>BsCXCRs</i> were classified in seven types, including <i>BsCXCR1a/1b</i>, <i>BsCXCR2</i>, <i>BsCXCR3a1/3a2</i>, <i>BsCXCR4a/4b</i>, and <i>BsCXCR5-7</i>, and <i>BsCXCR6</i> was the first <i>CXCR6</i> homologue experimentally identified in teleost fish. These BsCXCRs were further characterized in gene and protein structures, as well as phylogenetics, and the results revealed that BsCXCRs have expanded to divergent homologues. Our results showed that, in healthy fish, the <i>BsCXCR</i> transcripts was mainly distributed in the muscle and immune related organs, and that BsCXCR1a/1b proteins located in the cytomembrane, BsCXCR4a/4b/5/6 in the cytomembrane and perinuclear region, and BsCXCR3a1/3a2/7 in the cytomembrane, perinuclear region, and nuclear membrane, respectively. In skin injured fish, the transcripts of all <i>BsCXCRs</i> were transiently increased within one hour after injury, suggesting the involvement of <i>BsCXCRs</i> into the early inflammatory response to skin injury in the four-eyed sleeper. These results are valuable for understanding the evolutionary events of fish <i>CXCR</i> genes and provide insights into the roles of CXCR family in fish skin injury.