Qiu Jian-Feng, Cui Wen-Zhao, Zhang Qiang, Dai Tai-Ming, Liu Kai, Li Jiang-Lan, Wang Yu-Jun, Sima Yang-Hu, Xu Shi-Qing
School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, China, Jiangsu Province.
Institute of Agricultural Biotechnology & Ecology (IABE), Soochow University, Suzhou, China, Jiangsu Province.
Insect Sci. 2023 Feb;30(1):31-46. doi: 10.1111/1744-7917.13043. Epub 2022 May 17.
The circadian clock plays a critical role in the regulation of host immune defense. However, the mechanistic basis for this regulation is largely unknown. Herein, the core clock gene cryptochrome1 (cry1) knockout line in Bombyx mori, an invertebrate animal model, was constructed to obtain the silkworm with dysfunctional molecular clock, and the dynamic regulation of the circadian clock on the immune responsiveness within 24 h of Staphylococcus aureus infection was analyzed. We found that deletion of cry1 decreased viability of silkworms and significantly reduced resistance of larvae to S. aureus. Time series RNA-seq analysis identified thousands of rhythmically expressed genes, including immune response genes, in the larval immune tissue, fat bodies. Uninfected cry1 knockout silkworms exhibited expression patterns of rhythmically expressed genes similar to wild-type (WT) silkworms infected with S. aureus. However, cry1 knockout silkworms exhibited a seriously weakened response to S. aureus infection. The immune response peaked at 6 and 24 h after infection, during which "transcription storms" occurred, and the expression levels of the immune response genes, PGRP and antimicrobial peptides (AMPs), were significantly upregulated in WT. In contrast, cry1 knockout did not effectively activate Toll, Imd, or NF-κB signaling pathways during the immune adjustment period from 12 to 18 h after infection, resulting in failure to initiate the immune responsiveness peak at 24 h after infection. This may be related to inhibited silkworm fat body energy metabolism. These results demonstrated the dynamic regulation of circadian clock on silkworm immune response to bacterial infection and provided important insights into host antimicrobial defense mechanisms.
生物钟在宿主免疫防御的调节中起着关键作用。然而，这种调节的机制基础在很大程度上尚不清楚。在此，构建了无脊椎动物模型家蚕的核心生物钟基因隐花色素1（cry1）敲除系，以获得分子生物钟功能失调的家蚕，并分析了金黄色葡萄球菌感染后24小时内生物钟对免疫反应性的动态调节。我们发现，cry1的缺失降低了家蚕的活力，并显著降低了幼虫对金黄色葡萄球菌的抵抗力。时间序列RNA测序分析在幼虫免疫组织脂肪体中鉴定出数千个节律性表达的基因，包括免疫反应基因。未感染的cry1敲除家蚕表现出与感染金黄色葡萄球菌的野生型（WT）家蚕相似的节律性表达基因表达模式。然而，cry1敲除家蚕对金黄色葡萄球菌感染的反应严重减弱。免疫反应在感染后6小时和24小时达到峰值，在此期间发生“转录风暴”，WT中免疫反应基因、肽聚糖识别蛋白（PGRP）和抗菌肽（AMPs）的表达水平显著上调。相比之下，cry1敲除在感染后12至18小时的免疫调节期内没有有效激活Toll、Imd或NF-κB信号通路，导致在感染后24小时未能引发免疫反应峰值。这可能与家蚕脂肪体能量代谢受抑制有关。这些结果证明了生物钟对家蚕细菌感染免疫反应的动态调节，并为宿主抗菌防御机制提供了重要见解。
