Astragalus Polysaccharide Extends Lifespan via Mitigating Endoplasmic Reticulum Stress in the Silkworm, Bombyx mori
Jiangbo Song, Min Chen, Zhiquan Li, Jianfei Zhang, Hai Hu, Xiaoling Tong*, Fangyin Dai*
State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Biotechnology, Southwest University, Chongqing 400716, China
The traditional Chinese medicine Astragalus polysaccharide (APS) has been widely used to improve glucose homeostasis and immunoregulator properties. In recent years, it has also been shown to extend the lifespan of Caenorhabditis elegans; however, the underlying molecular mechanisms are not fully understood. Here, our study shows that APS could significantly extend adult stage, mean, and maximum lifespan of the silkworm, Bombyx mori and increase body weight without affecting food intake and fecundity. Meanwhile, the activities of glutathione S-transferase and superoxide dismutase are significantly enhanced, and the reaction oxygen species content is reduced concomitantly. Moreover, the activity of lysozyme is increased dramatically. In addition, APS rescues the shortened lifespan by Bacillus thuringiensis infection in silkworm. Furthermore, the transcription of the crucial genes involved in endoplasmic reticulum stress is upregulated upon the endoplasmic reticulum stress stimulation. APS also significantly ameliorates endoplasmic reticulum stress in silkworm cell line and in vivo. Together, the results of this study indicate that APS can prolong the silkworm lifespan by mitigating endoplasmic reticulum stress. This study improves our understanding of the molecular mechanism of APS-induced lifespan extension and highlights the importance of the silkworm as an experimental animal for evaluating the effects and revealing the mechanisms in lifespan extension of traditional Chinese medicine.
Song Jiangbo,Chen Min,Li Zhiquan, et al. Astragalus Polysaccharide Extends Lifespan via Mitigating Endoplasmic Reticulum Stress in the Silkworm, Bombyx mori[J]. Aging and disease,
2019, 10(6): 1187-1198.
Table 1 The primer sets used in this study for RT-qPCR.
Figure 1. The effective concentration of APS. (A-D) Survival curves of different APS concentrations in female and male silkworms. Log-rank test (Mantel-Cox) and Student’s t-test (two tailed) were used to evaluate the difference between the treatment and control groups. *p<0.05. **p<0.01. ***p<0.001.
Figure 2. Effect of APS on the lifespan of the silkworm. (A) Unmated females treated with APS (mean lifespan=41.0 d, n=33) lived longer than control female silkworms (mean lifespan= 39.5 d, n=36), p<0.001; (B) There was no significant difference between unmated males treated with APS (mean lifespan=37.96 d, n=42) and control male silkworms (mean lifespan=37.72 d, n=37), p=0.51. C. Unmated females treated with APS (maximum lifespan=43.79 d, n=4) lived longer than control female silkworms (maximum lifespan=41.28 d, n=4), p=0.0001; (D) There were no significant differences between unmated males treated with APS. (E) The maximum lifespan of treatment and control in female and male silkworm. Log-rank test (Mantel-Cox) and Student’s t-test (two tailed) were employed to evaluate the significance between the control and treatment groups. *p<0.05. **p<0.01. ***p<0.001. n.s., not significant.
Figure 3. Effect of APS on the diet, weight, and fecundity of the silkworm. (A-B) The impact on food intake of female and male silkworm chronically exposed to APS (n=20); (C) The impact on body weight of female silkworm chronically exposed to APS, L5D1 (meanCtrl =0.338 g, meanAPS=0.351 g, p=0.306, n=20), L5D5 (meanCtrl =1.618 g, meanAPS=1.662 g, p=0.025, n=20), P3 (meanCtrl =0.765 g, meanAPS=0.816 g, p=0.039, n=8); (D) The impact on the body weight of male silkworm chronically exposed to APS or respective controls, L5D1 (meanCtrl =0.274 g, meanAPS=0.278 g, p=0.69, n=20), L5D5 (meanCtrl =1.451 g, meanAPS=1.467 g, p=0.93, n=20), P3 (meanCtrl =0.552 g, meanAPS=0.604 g, p=0.020, n=9). Student’s t-test (two tailed) were employed to evaluate the significance. *p<0.05. n.s., not significant. (E) There were no significant differences between females treated with APS (fecundity =329, n=41) and control female silkworms (fecundity =333, n=46), p=0.635. Student’s t-test (two tailed) were employed to evaluate the significance. n.s., not significant.
Figure 4. Effects of APS on SOD and GST activity, and the content of MDA and ROS in the silkworm. (A) The standard curves of the SOD, the SOD activity of the fifth larval silkworm after 0.1% APS chronically treatment, L5D1 (Student’s t-test, two-tailed, n=9), L5D3 (Student’s t-test, two-tailed, n=9), L5D5 (Student’s t-test, two-tailed, n=9). (B) The standard curves of the GST, the GST activity of the fifth larval silkworm after 0.1% APS chronically treatment, L5D1 (Student’s t-test, two-tailed, n=9), L5D3 (Student’s t-test, two-tailed, n=9), L5D5 (Student’s t-test, two-tailed, n=9). (C) The standard curves of the MDA, the MDA content of the fifth larval silkworm after 0.1% APS chronically treatment, L5D1 (Student’s t-test, two-tailed, n=9), L5D3 (Student’s t-test, two-tailed, n=9), L5D5 (Student’s t-test, two-tailed, n=9). (D-E) The ROS content of the fifth larval silkworm after 0.1% APS chronically treatment, L5D3 (Student’s t-test, two-tailed, n=9), L5D5 (Student’s t-test, two-tailed, n=9).
Figure 5. Effect of APS on Att and lysozyme content, and survival condition in the silkworm. (A) Attacin content on day 3 of fifth instar larvae silkworm hemolymph after 0.1% APS chronic treatment, female (Student’s t-test, two-tailed, n=7), male (Student’s t-test, two-tailed, n=7). (B and C) Lysozyme content on day 3 of fifth instar larvae silkworm hemolymph after 0.1% APS chronic treatment in female and males (Student’s t-test, two-tailed, n=7); (D and E) Survival rates of Bacillus thuringiensis (BT)-infected silkworms after chronic exposures to APS, Log-rank test (Mantel-Cox), Female (n=7), Male (n=7).
Figure 6. Effects of APS on thapsigargin-induced ERS in BmN-SWU1 cells. (A) Expression levels of ERS-related genes in BmN-SWU1 cells treated with thapsigargin (n=6); (B and C) Effects of APS on the expression levels of BmBip and BmPERK in BmN-SWU1 cells after thapsigargin treatment (n=6); (D-I) Effects of APS on the expression levels of BmATF6, BmBip, and BmPERK in female and male silkworms (n=9). Student’s t-test, two-tailed, *** p<0.001; ** p<0.01; *p<0.05.
Figure 7. A model illustrating that APS extends lifespan via mitigating ER homeostasis by restricting Bip-PERK pathway activity.
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