Page 53 - 《水产学报》2026年第01期

1 期 严孟芝，等：大口黑鲈 IL-12 表达分析及异构体组成形式鉴定 50 卷

Characterizing IL-12 expression and identifying its isoform profiles in
largemouth bass (Micropterus salmoides)

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YAN Mengzhi , WANG Dandan , YANG Jing , LI Jie , ZENG Hui ,
1,2*
ZHANG Yongan , ZHOU Yang 1,2*
(1. College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China;
2. Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in
the Yangtze River Economic Belt, Ministry of Education, Huazhong Agricultural University, Wuhan 430070, China)
Abstract: Interleukin-12 (IL-12) is a heterodimeric cytokine composed of p40 and p35 subunits linked by an interchain disulf-
ide bond, and it plays a broad and essential role in the immune system. To characterize the molecular composition and function
of IL-12 isoforms in largemouth bass (Micropterus salmoides), we cloned the cDNA sequences of four IL-12 subunits (p35a,
p40a, p40b, and p40c) and analyzed their sequences, revealing conserved cysteine residues that are critical for disulfide bond
formation. We examined the tissue-specific expression profile of IL-12 subunits in M. salmoides using quantitative real-time
PCR (qPCR). Time-series transcriptome analysis was conducted to track expression changes of IL-12 subunit genes in M. sal-
moides following Nocardia seriolae infection. Two fusion proteins of IL-12 were overexpressed to investigate their functional
characteristics. The results indicated that the amino acid sequences of the four IL-12 subunits contain multiple conserved
cysteine residues involved in disulfide bonding. Tissue-specific expression profiling via qPCR revealed differential expression
patterns of these subunits across six organs (liver, spleen, head kidney, etc.). Time-series transcriptome analysis showed that the
p40c gene was persistently suppressed in both the head kidney and spleen, while p40b expression was continuously suppressed
in the head kidney and transiently upregulated in the spleen on the second day post-infection before gradually decreasing. Addi-
tionally, p35a, p40a, and p40b exhibited divergent expression profiles in the head kidney and spleen. Co-IP assays confirmed
interactions between p35a and p40b/p40c. Overexpression of the two fusion proteins p40b-p35a and p40c-p35a in M. sal-
moides demonstrated that both dimers formed by p40b+p35a and p40c+p35a significantly upregulated IFN-γ expression in the
spleen. Our study identifies two functional IL-12 isoforms in M. salmoides, composed of p40b+p35a and p40c+p35a, provid-
ing important insights into IL-12-mediated immune responses in teleost fish.
Key words: Micropterus salmoides; Interleukin-12; isoforms; Nocardia seriolae
Corresponding authors: ZHANG Yongan. E-mail: yonganzhang@hzau.edu.cn;
ZHOU Yang. E-mail: zhouyang@mail.hzau.edu
Funding projects: National Key Research and Development Program of China (2023YFD2400701); China Agriculture
Research System of MOF and MARA (CARS-46)

中国水产学会主办 sponsored by China Society of Fisheries https://www.china-fishery.cn
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