The swine acute diarrhea syndrome coronavirus spike protein promotes syncytial formation via upregulation of cellular cholesterol synthesis

ABSTRACT Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a novel coronavirus that causes acute diarrhea, vomiting, and high mortality in suckling piglets. Research has demonstrated that certain viruses enhance their replication by modulating intracellular cholesterol metabolism. However, the...

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Main Authors: Dakai Liu, Miaomiao Zeng, Jiyu Zhang, Liaoyuan Zhang, Hongyan Shi, Xin Zhang, Jialin Zhang, Jianfei Chen, Zhaoyang Ji, Xiuwen Li, Gengting Gu, Tingshuai Feng, Da Shi, Dongbo Sun, Li Feng
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Language:English
Published: American Society for Microbiology 2025-08-01
Series:mBio
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Online Access:https://journals.asm.org/doi/10.1128/mbio.00976-25
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author Dakai Liu
Miaomiao Zeng
Jiyu Zhang
Liaoyuan Zhang
Hongyan Shi
Xin Zhang
Jialin Zhang
Jianfei Chen
Zhaoyang Ji
Xiuwen Li
Gengting Gu
Tingshuai Feng
Da Shi
Dongbo Sun
Li Feng
author_facet Dakai Liu
Miaomiao Zeng
Jiyu Zhang
Liaoyuan Zhang
Hongyan Shi
Xin Zhang
Jialin Zhang
Jianfei Chen
Zhaoyang Ji
Xiuwen Li
Gengting Gu
Tingshuai Feng
Da Shi
Dongbo Sun
Li Feng
author_sort Dakai Liu
collection DOAJ
description ABSTRACT Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a novel coronavirus that causes acute diarrhea, vomiting, and high mortality in suckling piglets. Research has demonstrated that certain viruses enhance their replication by modulating intracellular cholesterol metabolism. However, the impact of SADS-CoV infection on cellular cholesterol synthesis remains unclear. Here, we found that SADS-CoV Spike (S) protein promoted syncytium formation by positively regulating cholesterol synthesis. Specifically, the virus upregulated the rate-limiting enzyme 3-hydroxy-3-methyl-glutaryl-CoA reductase through the inhibition of AMP-activated protein kinase (AMPK) activity. This inhibition was mediated by the activation of AKT-dependent phosphorylation of AMPKα at Ser485. Further investigation revealed that SADS-CoV S protein activated the PI3K/AKT pathway to promote cholesterol synthesis, a process that required the membrane protein integrin β1 (ITGB1). Importantly, we discovered that cholesterol facilitated cell-to-cell fusion mediated by the viral S protein, which enhanced syncytium formation. In summary, our findings demonstrate that the SADS-CoV S protein enhances cellular cholesterol accumulation by activating the PI3K/AKT/AMPK pathway through ITGB1, and that cholesterol facilitates syncytium formation mediated by the viral S protein. These insights contribute to a better understanding of SADS-CoV infection mechanisms and may inform future therapeutic strategies.IMPORTANCECholesterol, a vital component of cellular membranes, is crucial for maintaining cell structure and function. It also acts as an essential host factor for the entry, replication, and propagation of various viruses. In this study, we show that the Spike protein of swine acute diarrhea syndrome coronavirus (SADS-CoV) promotes syncytial formation by upregulating cellular cholesterol synthesis. The viral Spike protein activates the PI3K/AKT signaling pathway, leading to increased cholesterol production through the inhibition of AMP-activated protein kinase (AMPK). This upregulation of cholesterol facilitates cell-to-cell fusion, a process that enhances viral spread and pathogenesis. Moreover, we demonstrate that integrin β1 (ITGB1) acts as a critical host factor that links the viral Spike protein to the activation of the PI3K/AKT pathway. ITGB1 interacts with the S protein, playing a pivotal role in viral replication and cholesterol synthesis regulation. Our findings highlight the critical role of cholesterol in SADS-CoV infection and provide a deeper understanding of the molecular mechanisms behind viral replication. This research opens up potential therapeutic strategies targeting cholesterol metabolism to mitigate the effects of SADS-CoV and similar viral infections.
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publisher American Society for Microbiology
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spelling doaj-art-79033ceef24542a2b528e83ae962ae082025-08-20T03:36:01ZengAmerican Society for MicrobiologymBio2150-75112025-08-0116810.1128/mbio.00976-25The swine acute diarrhea syndrome coronavirus spike protein promotes syncytial formation via upregulation of cellular cholesterol synthesisDakai Liu0Miaomiao Zeng1Jiyu Zhang2Liaoyuan Zhang3Hongyan Shi4Xin Zhang5Jialin Zhang6Jianfei Chen7Zhaoyang Ji8Xiuwen Li9Gengting Gu10Tingshuai Feng11Da Shi12Dongbo Sun13Li Feng14State Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaCollege of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang, ChinaState Key Laboratory for Animal Disease Control and Prevention, Chinese Academy of Agricultural Sciences, Harbin Veterinary Research Institute, Harbin, ChinaABSTRACT Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a novel coronavirus that causes acute diarrhea, vomiting, and high mortality in suckling piglets. Research has demonstrated that certain viruses enhance their replication by modulating intracellular cholesterol metabolism. However, the impact of SADS-CoV infection on cellular cholesterol synthesis remains unclear. Here, we found that SADS-CoV Spike (S) protein promoted syncytium formation by positively regulating cholesterol synthesis. Specifically, the virus upregulated the rate-limiting enzyme 3-hydroxy-3-methyl-glutaryl-CoA reductase through the inhibition of AMP-activated protein kinase (AMPK) activity. This inhibition was mediated by the activation of AKT-dependent phosphorylation of AMPKα at Ser485. Further investigation revealed that SADS-CoV S protein activated the PI3K/AKT pathway to promote cholesterol synthesis, a process that required the membrane protein integrin β1 (ITGB1). Importantly, we discovered that cholesterol facilitated cell-to-cell fusion mediated by the viral S protein, which enhanced syncytium formation. In summary, our findings demonstrate that the SADS-CoV S protein enhances cellular cholesterol accumulation by activating the PI3K/AKT/AMPK pathway through ITGB1, and that cholesterol facilitates syncytium formation mediated by the viral S protein. These insights contribute to a better understanding of SADS-CoV infection mechanisms and may inform future therapeutic strategies.IMPORTANCECholesterol, a vital component of cellular membranes, is crucial for maintaining cell structure and function. It also acts as an essential host factor for the entry, replication, and propagation of various viruses. In this study, we show that the Spike protein of swine acute diarrhea syndrome coronavirus (SADS-CoV) promotes syncytial formation by upregulating cellular cholesterol synthesis. The viral Spike protein activates the PI3K/AKT signaling pathway, leading to increased cholesterol production through the inhibition of AMP-activated protein kinase (AMPK). This upregulation of cholesterol facilitates cell-to-cell fusion, a process that enhances viral spread and pathogenesis. Moreover, we demonstrate that integrin β1 (ITGB1) acts as a critical host factor that links the viral Spike protein to the activation of the PI3K/AKT pathway. ITGB1 interacts with the S protein, playing a pivotal role in viral replication and cholesterol synthesis regulation. Our findings highlight the critical role of cholesterol in SADS-CoV infection and provide a deeper understanding of the molecular mechanisms behind viral replication. This research opens up potential therapeutic strategies targeting cholesterol metabolism to mitigate the effects of SADS-CoV and similar viral infections.https://journals.asm.org/doi/10.1128/mbio.00976-25swine acute diarrhea syndrome coronaviruscholesterolspike proteinsyncytia
spellingShingle Dakai Liu
Miaomiao Zeng
Jiyu Zhang
Liaoyuan Zhang
Hongyan Shi
Xin Zhang
Jialin Zhang
Jianfei Chen
Zhaoyang Ji
Xiuwen Li
Gengting Gu
Tingshuai Feng
Da Shi
Dongbo Sun
Li Feng
The swine acute diarrhea syndrome coronavirus spike protein promotes syncytial formation via upregulation of cellular cholesterol synthesis
mBio
swine acute diarrhea syndrome coronavirus
cholesterol
spike protein
syncytia
title The swine acute diarrhea syndrome coronavirus spike protein promotes syncytial formation via upregulation of cellular cholesterol synthesis
title_full The swine acute diarrhea syndrome coronavirus spike protein promotes syncytial formation via upregulation of cellular cholesterol synthesis
title_fullStr The swine acute diarrhea syndrome coronavirus spike protein promotes syncytial formation via upregulation of cellular cholesterol synthesis
title_full_unstemmed The swine acute diarrhea syndrome coronavirus spike protein promotes syncytial formation via upregulation of cellular cholesterol synthesis
title_short The swine acute diarrhea syndrome coronavirus spike protein promotes syncytial formation via upregulation of cellular cholesterol synthesis
title_sort swine acute diarrhea syndrome coronavirus spike protein promotes syncytial formation via upregulation of cellular cholesterol synthesis
topic swine acute diarrhea syndrome coronavirus
cholesterol
spike protein
syncytia
url https://journals.asm.org/doi/10.1128/mbio.00976-25
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