Genome-wide analysis unveils the differentiated "external" and "internal" lectin system in the tropical sea cucumber Holothuria leucospilota

  • Dev Comp Immunol. 2025 Dec:173:105527. doi: 10.1016/j.dci.2025.105527.
Xinyue Ren  1 ,  Zhou Qin  2 ,  Renhui Liu  1 ,  Ting Chen  2 ,  Tiehao Lin  3 ,  Xinyu Sun  1 ,  Jiasheng Huang  2 ,  Wenjie Pan  2 ,  Caixia Long  1 ,  Chunhua Ren  2 ,  Haipeng Qin  4 ,  Peiming Zheng  5 ,  Aifen Yan  6 ,  Lihong Yuan  7
Affiliations
  • 1. School of Life Sciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, 510006, PR China.
  • 2. State Key Laboratory of Breeding Biotechnology and Sustainable Aquaculture, Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China.
  • 3. Guangdong Institute for Drug Control, Guangzhou, 5106630, PR China.
  • 4. Agro-Tech Extension Center of Guangdong Province, Huizhou, 516081, PR China.
  • 5. Guangdong Jinyang Biotechnology Co., Ltd, Maoming, 525027, PR China.
  • 6. School of Medicine, Foshan University, Foshan, 528000, PR China. Electronic address: [email protected].
  • 7. School of Life Sciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, 510006, PR China. Electronic address: [email protected].
PMID: 41274536 DOI: 10.1016/j.dci.2025.105527
Abstract

To date, the understanding of lectin-related immunity in sea cucumbers remains limited. Through a comprehensive genome-wide analysis, 133 lectin genes were identified from Holothuria leucospilota, a sea cucumber species with high ecological and economic significance in the Pacific and Indian Oceans. These lectins were classified into five subtypes, with C-type lectin being the predominant form, and the presence of SUEL-like lectin and Malectin reported here for the first time in sea cucumbers. Transcriptomic analysis across twelve tissues and sixteen developmental stages revealed ubiquitous expression of H. leucospilota lectins. A key finding was the compartmentalization of lectin systems: SUEL-like lectins expressed in the body wall constitute an "external" defense system, while C-type lectins produced by coelomocytes form an "internal" immune system. This spatial and functional specialization reflects a sophisticated immune strategy in invertebrates, enabling targeted pathogen recognition at different bodily interfaces. Furthermore, distinct immune responses to Vibrio, LPS, and poly(I:C) were observed among different lectins. We also identified an ovary-specific C-type lectin, suggesting a potential role in early embryonic development. This study not only fills a knowledge gap regarding lectin genes in sea cucumbers but also establishes a broader framework for understanding complex immune mechanisms in echinoderms.

Keywords
Holothuria leucospilota; Immune function; Lectin; Pathogenic challenge.
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