Transport of polyomavirus across the ER membrane

描述（由申请人提供）：病毒是强效的致癌剂。虽然癌症的临床效应是明显的，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，多瘤病毒是一种诱导小鼠癌症的非包膜DNA肿瘤病毒。为了感染细胞，Py与质膜上的受体结合并进入内质网（ER），在那里它劫持细胞机器穿过内质网膜并到达细胞质溶胶。然后，病毒被运送到细胞核中，在那里病毒DNA的转录和复制随之而来，导致不受控制的细胞增殖和癌症。Py如何通过内质网膜运输仍不清楚，这是一个非常有趣的话题。使用体外生化方法，我们建议确定内质网因子(s)，促进Py从内质网转运到细胞质，并阐明这一过程的分子机制。接下来，我们将采用体内细胞生物学的方法来探讨这些内质网因子在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述了基本的细胞事件；因此，Py参与细胞机械穿越内质网膜将阐明基本的膜运输过程。此外，确定Py在感染过程中所选择的细胞靶标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病毒、BK病毒和乳头状瘤病毒，从Py的细胞进入机制中收集的经验教训可能应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.