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Bu, Xia

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Bu, Xia
Author's Publications: search.filters.isAuthorOfPublication.c17ddf5c-f91d-4d45-967a-65f16fa9ffec

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    Cyclin D-CDK4 kinase destabilizes PD-L1 via Cul3SPOP to control cancer immune surveillance
    (2017) Zhang, Jinfang; Bu, Xia; Wang, Haizhen; Zhu, Yasheng; Geng, Yan; Nihira, Naoe; Tan, Yuyong; Ci, Yanpeng; Wu, Fei; Dai, Xiangpeng; Guo, Jianping; Huang, Yu-Han; Fan, Caoqi; Ren, Shancheng; Sun, Yinghao; Freeman, Gordon; Sicinski, Piotr; Wei, Wenyi
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    RGMb is a novel binding partner for PD-L2 and its engagement with PD-L2 promotes respiratory tolerance
    (The Rockefeller University Press, 2014) Xiao, Yanping; Yu, Sanhong; Zhu, Baogong; Bedoret, Denis; Bu, Xia; Francisco, Loise; Hua, Ping; Duke-Cohan, Jonathan; Umetsu, Dale T.; Sharpe, Arlene; DeKruyff, Rosemarie H.; Freeman, Gordon
    We report that programmed death ligand 2 (PD-L2), a known ligand of PD-1, also binds to repulsive guidance molecule b (RGMb), which was originally identified in the nervous system as a co-receptor for bone morphogenetic proteins (BMPs). PD-L2 and BMP-2/4 bind to distinct sites on RGMb. Normal resting lung interstitial macrophages and alveolar epithelial cells express high levels of RGMb mRNA, whereas lung dendritic cells express PD-L2. Blockade of the RGMb–PD-L2 interaction markedly impaired the development of respiratory tolerance by interfering with the initial T cell expansion required for respiratory tolerance. Experiments with PD-L2–deficient mice showed that PD-L2 expression on non–T cells was critical for respiratory tolerance, but expression on T cells was not required. Because PD-L2 binds to both PD-1, which inhibits antitumor immunity, and to RGMb, which regulates respiratory immunity, targeting the PD-L2 pathway has therapeutic potential for asthma, cancer, and other immune-mediated disorders. Understanding this pathway may provide insights into how to optimally modulate the PD-1 pathway in cancer immunotherapy while minimizing adverse events.
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    TIM-family Proteins Promote Infection of Multiple Enveloped Viruses through Virion-associated Phosphatidylserine
    (Public Library of Science, 2013) Jemielity, Stephanie; Wang, Jinyize J.; Chan, Ying Kai; Ahmed, Asim; Li, Wenhui; Monahan, Sheena; Bu, Xia; Farzan, Michael; Freeman, Gordon; Umetsu, Dale; DeKruyff, Rosemarie H.; Choe, Hyeryun
    Human T-cell Immunoglobulin and Mucin-domain containing proteins (TIM1, 3, and 4) specifically bind phosphatidylserine (PS). TIM1 has been proposed to serve as a cellular receptor for hepatitis A virus and Ebola virus and as an entry factor for dengue virus. Here we show that TIM1 promotes infection of retroviruses and virus-like particles (VLPs) pseudotyped with a range of viral entry proteins, in particular those from the filovirus, flavivirus, New World arenavirus and alphavirus families. TIM1 also robustly enhanced the infection of replication-competent viruses from the same families, including dengue, Tacaribe, Sindbis and Ross River viruses. All interactions between TIM1 and pseudoviruses or VLPs were PS-mediated, as demonstrated with liposome blocking and TIM1 mutagenesis experiments. In addition, other PS-binding proteins, such as Axl and TIM4, promoted infection similarly to TIM1. Finally, the blocking of PS receptors on macrophages inhibited the entry of Ebola VLPs, suggesting that PS receptors can contribute to infection in physiologically relevant cells. Notably, infection mediated by the entry proteins of Lassa fever virus, influenza A virus and SARS coronavirus was largely unaffected by TIM1 expression. Taken together our data show that TIM1 and related PS-binding proteins promote infection of diverse families of enveloped viruses, and may therefore be useful targets for broad-spectrum antiviral therapies.