Transport of polyomavirus across the ER membrane

描述(申请人提供)：病毒是有效的致癌物质。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不完全清楚。在这里，我们建议研究多瘤病毒(Py)的细胞进入机制，Py是一种诱导小鼠癌症的无包膜DNA肿瘤病毒。为了感染细胞，Py与质膜上的一个受体结合，并到达内质网(ER)，在那里它劫持细胞机穿过ER膜到达胞浆。然后病毒被运送到细胞核，在那里病毒DNA的转录和复制接踵而至，导致细胞不受控制的增殖和癌症。Py是如何通过内质网膜转运的仍不清楚，这是一个非常感兴趣的课题。利用体外生化方法，我们建议鉴定促进Py从内质网进入胞浆的ER因子(S)，并阐明这一过程的分子机制。接下来，我们将使用体内细胞生物学方法来探讨这些ER因子在Py感染中的生理作用。病原体与它们各自的宿主细胞之间的相互作用阐述了基本的细胞事件；因此，Py参与细胞机制穿越内质网将阐明基本的膜运输过程。此外，识别Py在感染过程中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Py的许多结构相关病毒是人类病原体，如JC、BK和乳头状瘤病毒，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.