Cai Rui, Chen Xinyu, Yang Wan, Wang Xin, Sun Le, Zhao Ping, Xia Qingyou, He Huawei, Wang Yejing
State Key Laboratory of Silkworm Genome Biology, Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing, China.
State Key Laboratory of Silkworm Genome Biology, Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing, China; Chongqing Key Laboratory of Sericultural Science, Chongqing Engineering and Technology Research Center for Novel Silk Materials, Southwest University, Chongqing, China.
Int J Biol Macromol. 2023 Jan 15;225:715-729. doi: 10.1016/j.ijbiomac.2022.11.135. Epub 2022 Nov 18.
Tissue/organ remodeling and cells fate determination play key roles in the life cycle of animals. However, they are still poorly understood in insects, especially in the silkworm. The anterior silk gland (ASG) of the silkworm is essential for the formation and performance of silk fibers, but the regulatory mechanism of ASG remodeling and cells fate determination is less known. Here we found that silencing of POUM2 caused shorter ASG length, intimal structural defects, silkworm spinning failure, and the resultant naked pupae death, but cells number was not affected. Cells staining showed that DNA endoreduplication was not affected in the ASG. Transmission electron microscopy and chitin staining showed cuticle proteins and chitin were greatly reduced in the ASG during the molting period. Transcriptional analysis showed the expression profiles of cuticle proteins and chitin synthase were similar to that of POUM2 during the molting period, and POUM2 down-regulation reduced the expression of cuticle proteins, chitin synthase, autophagy and apoptosis-related genes. While the phenotype resulting from POUM2 over-expression was similar to that of POUM2 down-regulation. Cells staining revealed marked cells apoptosis with cells number reduction and inhibition of DNA endoreduplication in the ASG. Transcriptional analysis showed the expression of autophagy and apoptosis-related genes, and some cuticle proteins and chitin synthase were significantly up-regulated. The results suggest that POUM2 homeostasis regulates ASG intimal remodeling and cells fate, thus affecting ASG development, silkworm spinning and metamorphosis. Our studies not only offer potential molecular targets for genetic improvement of silk performance and molecular breeding of the silkworm, but also provide new insights into POU factor-mediated tissue remodeling and cells fate determination in insects.
组织/器官重塑和细胞命运决定在动物生命周期中起着关键作用。然而，在昆虫中，尤其是在家蚕中，人们对它们的了解仍然很少。家蚕的前部丝腺对于丝纤维的形成和性能至关重要，但前部丝腺重塑和细胞命运决定的调控机制却鲜为人知。在这里，我们发现沉默POUM2会导致前部丝腺长度缩短、内膜结构缺陷、家蚕吐丝失败以及裸蛹死亡，但细胞数量不受影响。细胞染色显示前部丝腺中的DNA核内复制不受影响。透射电子显微镜和几丁质染色显示，在蜕皮期，前部丝腺中的表皮蛋白和几丁质大大减少。转录分析表明，在蜕皮期，表皮蛋白和几丁质合酶的表达谱与POUM2相似，POUM2下调会降低表皮蛋白、几丁质合酶、自噬和凋亡相关基因的表达。而POUM2过表达产生的表型与POUM2下调相似。细胞染色显示前部丝腺中明显的细胞凋亡，细胞数量减少且DNA核内复制受到抑制。转录分析表明自噬和凋亡相关基因以及一些表皮蛋白和几丁质合酶的表达显著上调。结果表明，POUM2的稳态调节前部丝腺内膜重塑和细胞命运，从而影响前部丝腺发育、家蚕吐丝和变态。我们的研究不仅为蚕丝性能的遗传改良和家蚕分子育种提供了潜在的分子靶点，也为昆虫中POU因子介导的组织重塑和细胞命运决定提供了新的见解。
