Transport of polyomavirus across the ER membrane

性状（由申请方提供）：病毒是强效致癌剂。虽然癌症的临床影响是显而易见的，但其细胞和分子原因尚未完全了解。在这里，我们建议研究多瘤病毒（Py），一种无包膜的DNA肿瘤病毒，在小鼠中诱导癌症的细胞进入机制。为了感染细胞，Py与质膜上的受体结合并行进到内质网（ER），在内质网中它劫持细胞机器以穿过ER膜并到达胞质溶胶。然后病毒被运送到细胞核中，在那里病毒DNA的转录和复制随之发生，导致不受控制的细胞增殖和癌症。Py如何穿过ER膜转运仍不清楚，并且是一个非常感兴趣的主题。使用体外生化方法，我们建议鉴定促进Py从ER转运到细胞质的ER因子，并阐明该过程的分子机制。接下来，我们将采用体内细胞生物学方法来探测这些ER因子在Py感染中的生理作用。病原体和它们各自的宿主细胞之间的相互作用阐明了基本的细胞事件;因此，Py参与细胞机器穿过ER膜将阐明基本的膜转运过程。此外，确定Py在感染期间选择的细胞靶点可能会导致允许选择性干扰的药物的开发。由于许多与Py结构相关的病毒都是人类病原体，如JC、BK和乳头状瘤病毒，因此从Py的细胞进入机制中获得的经验教训可能适用于更广泛的人类疾病。

DESCRIPTION (provided by applicant): Viruses are potent cancer-inducing agents. While the clinical effects of cancer are obvious, its cellular and molecular causes are not fully understood. Here we propose to study the cellular entry mechanisms of polyomavirus (Py), a non-enveloped DNA tumor virus that induces cancer in mice. To infect cells, Py binds to a receptor at the plasma membrane and travels to the endoplasmic reticulum (ER) where it hijacks cellular machineries to cross the ER membrane and reach the cytosol. The virus is then transported into the nucleus where transcription and replication of the viral DNA ensue, leading to uncontrolled cell proliferation and cancer. How Py is transported across the ER membrane remains unclear and is a subject of intense interest. Using an in vitro biochemical approach, we propose to identify the ER factor(s) that facilitate the transport of Py from the ER into the cytosol and to clarify the molecular mechanism of this process. Next, we will employ an in vivo cell biological method to probe the physiological role of these ER factors in Py infection. Interactions between pathogens and their respective host cells expound on basic cellular events; thus, Py's engagement of cellular machineries to cross the ER membrane will elucidate fundamental membrane transport processes. Moreover, identifying the cellular targets that Py co-opts during infection may lead to the development of drugs that allow selective interference. As many of Py's structurally-related viruses are human pathogens, such as the JC, BK, and papilloma viruses, the lessons gleaned from the cellular entry mechanism of Py may be applied to a broader spectrum of human diseases.