Laboratory of Quality and Safety Risk Assessment for Agro-Products of the Ministry of Agriculture (Jinan), Institute of Quality Standard and Testing Technology for Agro-Products, Shandong Academy of Agricultural Sciences, Jinan 250100, China.
Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
Int J Mol Sci. 2023 Jun 27;24(13):10700. doi: 10.3390/ijms241310700.
C-type lectins (CTLs) are a class of proteins containing carbohydrate recognition domains (CRDs), which are characteristic modules that recognize various glycoconjugates and function primarily in immunity. CTLs have been reported to affect growth and development and positively regulate innate immunity in . However, the regulatory mechanisms of TcCTL16 proteins are still unclear. Here, spatiotemporal analyses displayed that was highly expressed in late pupae and early adults. RNA interference in early larvae shortened their body length and narrowed their body width, leading to the death of 98% of the larvae in the pupal stage. Further analysis found that the expression level of muscle-regulation-related genes, including , , , , and , and muscle-composition-related genes, including and , were obviously down-regulated after silencing in . In addition, the transcription of was mainly distributed in the hemolymph. was significantly upregulated after challenges with lipopolysaccharides, peptidoglycans, , and . Recombinant CRDs of TcCTL16 bind directly to the tested bacteria (except ); they also induce extensive bacterial agglutination in the presence of Ca. On the contrary, after silencing in the late larval stage, were able to develop normally. Moreover, the transcript levels of seven antimicrobial peptide genes (, , , , , , and ) and one transcription factor gene () were significantly increased under challenge and led to an increased survival rate of when infected with or , suggesting that TcCTL16 deficiency could be compensated for by increasing AMP expression via the IMD pathways in . In conclusion, this study found that TcCTL16 could be involved in developmental regulation in early larvae and compensate for the loss of CTL function by regulating the expression of AMPs in late larvae, thus laying a solid foundation for further studies on CTLs.
C 型凝集素（CTLs）是一类含有碳水化合物识别结构域（CRDs）的蛋白质，CRDs 是识别各种糖缀合物的特征模块，主要在免疫中发挥作用。CTLs 被报道影响生长和发育，并正向调节先天免疫。然而，TcCTL16 蛋白的调控机制尚不清楚。本研究时空分析显示 在晚期蛹和早期成虫中高度表达。早期幼虫的 RNA 干扰缩短了其体长并使其体宽变窄，导致 98%的幼虫在蛹期死亡。进一步分析发现，肌肉调节相关基因（包括 、 、 、 、和 ）和肌肉组成相关基因（包括 和 ）的表达水平在 沉默后明显下调。此外， 的转录主要分布在血淋巴中。在受到脂多糖、肽聚糖、酵母聚糖和 等刺激后， 的转录水平显著上调。TcCTL16 的 CRDs 重组蛋白直接结合测试细菌（除 外）；它们在存在 Ca 的情况下还会引起广泛的细菌凝集。相反，在晚期幼虫期沉默后， 能够正常发育。此外，在 或 感染后，七种抗菌肽基因（ 、 、 、 、 、 和 ）和一个转录因子基因（ ）的转录水平显著增加，导致 的存活率提高，这表明 TcCTL16 缺陷可以通过 IMD 途径增加 AMP 表达来得到补偿。总之，本研究发现 TcCTL16 可能参与早期幼虫的发育调控，并通过调节晚期幼虫 AMP 的表达来补偿 CTL 功能的丧失，为进一步研究 CTLs 奠定了基础。
