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Theranostics 2020; 10(20):9032-9049. doi:10.7150/thno.46921 This issue Cite

Research Paper

Autophagic degradation of PML promotes susceptibility to HSV-1 by stress-induced corticosterone

Wen Li^1,2,3#, Zhuo Luo^1,2,3#, Chang-Yu Yan^1,2,3, Xiao-Hua Wang^1,2,3, Zheng-Jie He^4,5, Shu-Hua Ouyang^1,2,3, Chang Yan^1,2,3, Li-Fang Liu^1,2,3, Qing-Qing Zhou^1,2,3, Han-Lu Mu^1,2,3, Hai-Biao Gong^1,2,3, Wen-Jun Duan^1,2,3, Lei Liang^1,2,3, Hiroshi Kurihara^1,2,3, Du Feng^4,5✉, Yi-Fang Li^1,2,3✉, Rong-Rong He^1,2,3✉

1. Guangdong Engineering Research Center of Chinese Medicine & Disease Susceptibility, Jinan University, Guangzhou 510632, China.
2. International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, Guangzhou 510632, China.
3. Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China.
4. Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou; Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.
5. State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China.
#These authors contributed equally to this work.

✉ Corresponding authors: E-mail: rongrongheedu.cn (R.R.H.); Tel.: +86-208-522-7791; Fax: +86-208-522-1559. E-mail: liyifang706edu.cn (Y.F.L.) or Fenglabedu.cn (D.F.).

Abstract

Rationale: Herpes simplex virus type 1 (HSV-1) is a neurotropic virus that can cause a variety of clinical syndromes including mucocutaneous disease and HSV-1 encephalitis (HSE). Here, we characterize the molecular mechanisms underlying the susceptibility to HSV-1 under stressful conditions.

Methods: Restraint stress and corticosterone (CORT, a primary stress hormone) were respectively used to establish HSV-1 susceptible model in vivo and in vitro. Viral titers were determined by plaque assay. Western blotting, immunofluorescence, transmission electron microscopy (TEM), qRT-PCR, H&E staining, IHC staining and flow cytometry were employed to evaluate virus-related protein expressions and detect the activation of autophagy. Loss- and gain-function assays, co-immunoprecipitation (co-IP) technique and autophagy agonist/antagonist treatments were applied in mechanistic experiments.

Results: Restraint stress increased the susceptibility of mouse brain to HSV-1. Similarly, CORT treatment enhanced the susceptibility of neural cells to HSV-1. Furthermore, PML protein level in HSV-1 infected brain tissues and neural cells was remarkably decreased by stress treatment in vivo or CORT treatment in vitro, while its transcriptional level was not affected. Notably, a striking decline in protein expressions of ICP27 and gB was observed in PML-overexpressing cells, which was reversed by CORT treatment. By contrast, protein expression of gB was increased by knockdown with si-PML in virus-infected SH-SY5Y cells. We further discovered that CORT-driven PML degradation was dependent on the activation of autophagy in a ULK1-independent manner, rather than proteasome pathway. Bafilomycin A1 (BaF1) attenuated the augmentation effect of CORT on HSV-1 infection. The expressions of viral proteins were reduced in LC3-depleted cells, and the degradation of PML by CORT-induced autophagy was prevented in cells with LC3 knockdown by RNAi. Interestingly, PML was revealed to interact with the autophagic cargo receptor P62 and the autophagic effector protein LC3. Additionally, CORT failed to increase gB protein level when PML was silenced, providing direct evidence linking autophagic degradation of PML and CORT-induced virus susceptibility.

Conclusion: Our results revealed that restraint stress/CORT increased HSV-1 susceptibility by delivering PML into autolysosomes for degradation. The results obtained from in vitro and in vivo models not only demonstrated the adverse effects of stress on HSV-1 infection, but also systematically investigated the underlying molecular mechanisms. These discoveries broaden our understanding of the interplay between host and viruses, and a comprehensive understanding of the role of autophagy in viral infection will provide information for future development of innovative drugs against viral infection.

Keywords: Stress, CORT, HSV-1, Autophagy, PML

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