To dissect the role of PERK-mediated apoptosis in the pathogenesis of MERS-CoV

Professor Chu, Hin   (Principal Investigator (PI))

24

2019-05-01

2021-04-30

53260

To dissect the role of PERK-mediated apoptosis in the pathogenesis of MERS-CoV

apoptosis, MERS-CoV, PERK

VirologyMicrobiology

201811159126

Seed Fund for PI Research – Basic Research

2018

Completed

Middle East respiratory syndrome coronavirus (MERS-CoV) was first identified in 2012 in Saudi Arabia (1). As of September 2018, the virus has resulted in 2229 cases with 791 deaths in 27 countries. Despite extensive research effort, currently there is no specific medical countermeasure proven to be effective against MERS-CoV infection. Corticosteroid therapy, which has been used to treat severe MERS-CoV infections, may not improve the clinical outcome and is associated with a longer duration of viral clearance (2). MERS-CoV infection results in severe acute respiratory syndrome (SARS)-like disease including pneumonia, acute respiratory distress syndrome (ARDS), as well as extrapulmonary manifestations (3). Despite the high resemblance between MERS and SARS, the case-fatality rate of MERS is approximately 35%, which is three times than that of SARS. To date, the high pathogenicity of MERS-CoV infection remains poorly understood. Histopathological studies demonstrated pneumocyte damage and suggested direct cytopathic effects contributed to MERS symptoms (4, 5). An earlier study utilizing ex vivo lung tissue and patient bronchoalveolar lavage (BAL) samples similarly observed detachment and disruption of the alveolar membrane upon MERS-CoV infection and suggested that virus-induced apoptosis contributed to the alveolar damage and lung injury upon MERS-CoV infection (6). In line with this observation, others and us have previously demonstrated that MERS-CoV triggered apoptosis in human lung epithelial cells (7), human primary T cells (8) as well as the lung and kidney of MERS-CoV-infected marmosets (9). Apoptosis is a highly regulated form of cell death that can be initiated by the host to limit virus propagation. However, excessive apoptosis at the alveolar epithelium contributes to lung injury and ARDS (10). Most of the current knowledge on human coronavirus-related apoptosis was from studies on SARS-CoV. SARS-CoV-induced apoptosis was described in multiple tissues in infected patients (11-13) and a number of diverse mechanisms have been proposed for SARS-CoV-induced apoptosis (14-16). In contrast, although recent reports recognized that MERS-CoV infections resulted in apoptosis (6-9), the mechanism of MERS-CoV-induced apoptosis remains largely unexplored. Most importantly, despite apoptosis has been described in SARS-CoV and MERS-CoV infections, the role of apoptosis on the pathogenesis of the highly pathogenic human coronaviruses has never been evaluated. With a series of preliminary experiments, we demonstrated that the membrane (M) protein of MERS-CoV potently triggered apoptosis. Next, with confocal microscopy of M-expressing cells, we noticed that MERS-CoV M colocalized with and redistributed the key endoplasmic reticulum (ER) stress regulator, 78-kDa glucose-regulated protein (GRP78). In parallel, MERS-CoV infection or M protein expression significantly upregulated the protein kinase R-like endoplasmic reticulum kinase (PERK) pathway, which is an ER stress sensing pathway regulated by GRP78. Importantly, inhibiting the activity of PERK with a recently developed selective small molecular inhibitor potently attenuated MERS-CoV-induced apoptosis, suggesting the PERK-signaling played a predominant role MERS-CoV-induced apoptosis. In the present study, we aim to further dissect the mechanism of PERK-mediated apoptosis and investigate the physiopathological relevance of apoptosis in the pathogenesis of MERS-CoV with a combination of in vitro, human primary airway epithelial cell, and in vivo transgenic mouse models. REFERENCE: 1. Zaki AM, van Boheemen S, Bestebroer TM, et al. Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. N Engl J Med 2012; 367: 1814-1820. 2. Arabi YM, Mandourah Y, Al-Hameed F, et al. Corticosteroid Therapy for Critically Ill Patients with Middle East Respiratory Syndrome. Am J Respir Crit Care Med 2018; 197: 757-767. 3. Assiri A, Al-Tawfiq JA, Al-Rabeeah AA, et al. Epidemiological, demographic, and clinical characteristics of 47 cases of Middle East respiratory syndrome coronavirus disease from Saudi Arabia: a descriptive study. Lancet Infect Dis 2013; 13: 752-761. 4. Alsaad KO, Hajeer AH, Al Balwi M, et al. Histopathology of Middle East respiratory syndrome coronovirus (MERS-CoV) infection - clinicopathological and ultrastructural study. Histopathology 2018; 72: 516-524. 5. Ng DL, Al Hosani F, Keating MK, et al. Clinicopathologic, Immunohistochemical, and Ultrastructural Findings of a Fatal Case of Middle East Respiratory Syndrome Coronavirus Infection in the United Arab Emirates, April 2014. Am J Pathol 2016; 186: 652-658. 6. Hocke AC, Becher A, Knepper J, et al. Emerging human middle East respiratory syndrome coronavirus causes widespread infection and alveolar damage in human lungs. Am J Respir Crit Care Med 2013; 188: 882-886. 7. Tao X, Hill TE, Morimoto C, et al. Bilateral entry and release of Middle East respiratory syndrome coronavirus induces profound apoptosis of human bronchial epithelial cells. J Virol 2013; 87: 9953-9958. 8. Chu H, Zhou J, Wong BH, et al. Middle East Respiratory Syndrome Coronavirus Efficiently Infects Human Primary T Lymphocytes and Activates the Extrinsic and Intrinsic Apoptosis Pathways. J Infect Dis 2016; 213: 904-914. 9. Yeung ML, Yao Y, Jia L, et al. MERS coronavirus induces apoptosis in kidney and lung by upregulating Smad7 and FGF2. Nat Microbiol 2016; 1: 16004. 10. Matthay MA, Zemans RL. The acute respiratory distress syndrome: pathogenesis and treatment. Annu Rev Pathol 2011; 6: 147-163. 11. Chau TN, Lee KC, Yao H, et al. SARS-associated viral hepatitis caused by a novel coronavirus: report of three cases. Hepatology 2004; 39: 302-310. 12. Ding Y, Wang H, Shen H, et al. The clinical pathology of severe acute respiratory syndrome (SARS): a report from China. J Pathol 2003; 200: 282-289. 13. Wei L, Sun S, Xu CH, et al. Pathology of the thyroid in severe acute respiratory syndrome. Hum Pathol 2007; 38: 95-102. 14. Kopecky-Bromberg SA, Martinez-Sobrido L, Palese P. 7a protein of severe acute respiratory syndrome coronavirus inhibits cellular protein synthesis and activates p38 mitogen-activated protein kinase. J Virol 2006; 80: 785-793. 15. Tan YX, Tan TH, Lee MJ, et al. Induction of apoptosis by the severe acute respiratory syndrome coronavirus 7a protein is dependent on its interaction with the Bcl-XL protein. J Virol 2007; 81: 6346-6355. 16. Krahling V, Stein DA, Spiegel M, et al. Severe acute respiratory syndrome coronavirus triggers apoptosis via protein kinase R but is resistant to its antiviral activity. J Virol 2009; 83: 2298-2309.