Departments of Pharmacology, Physiology and Biophysics, Boston University, Boston, MA 02215, USA.
Center for Network Systems Biology, Boston University, Boston, MA 02215, USA.
Hum Mol Genet. 2023 Oct 4;32(20):2966-2980. doi: 10.1093/hmg/ddad122.
Aggregation of TAR DNA-binding protein 43 kDa (TDP-43) is thought to drive the pathophysiology of amyotrophic lateral sclerosis and some frontotemporal dementias. TDP-43 is normally a nuclear protein that in neurons translocates to the cytoplasm and can form insoluble aggregates upon activation of the integrated stress response (ISR). Viruses evolved to control the ISR. In the case of Herpesvirus 8, the protein ORF57 acts to bind protein kinase R, inhibit phosphorylation of eIF2α and reduce activation of the ISR. We hypothesized that ORF57 might also possess the ability to inhibit aggregation of TDP-43. ORF57 was expressed in the neuronal SH-SY5Y line and its effects on TDP-43 aggregation characterized. We report that ORF57 inhibits TDP-43 aggregation by 55% and elicits a 2.45-fold increase in the rate of dispersion of existing TDP-43 granules. These changes were associated with a 50% decrease in cell death. Proteomic studies were carried out to identify the protein interaction network of ORF57. We observed that ORF57 directly binds to TDP-43 as well as interacts with many components of the ISR, including elements of the proteostasis machinery known to reduce TDP-43 aggregation. We propose that viral proteins designed to inhibit a chronic ISR can be engineered to remove aggregated proteins and dampen a chronic ISR.
聚集的 TAR DNA 结合蛋白 43 kDa（TDP-43）被认为是肌萎缩侧索硬化症和一些额颞叶痴呆的病理生理学的驱动因素。TDP-43 通常是一种核蛋白，在神经元中转位到细胞质中，并在整合应激反应（ISR）激活时可以形成不溶性聚集体。病毒进化来控制 ISR。在疱疹病毒 8 的情况下，蛋白 ORF57 作用于结合蛋白激酶 R，抑制 eIF2α 的磷酸化，并减少 ISR 的激活。我们假设 ORF57 也可能具有抑制 TDP-43 聚集的能力。ORF57 在神经元 SH-SY5Y 系中表达，并对 TDP-43 聚集进行了特征描述。我们报告说，ORF57 通过 55%抑制 TDP-43 聚集，并使现有的 TDP-43 颗粒的分散速度增加 2.45 倍。这些变化与细胞死亡减少 50%相关。进行了蛋白质组学研究以鉴定 ORF57 的蛋白质相互作用网络。我们观察到 ORF57 直接与 TDP-43 结合，并且与 ISR 的许多成分相互作用，包括已知可减少 TDP-43 聚集的蛋白稳态机制的元素。我们提出，设计用于抑制慢性 ISR 的病毒蛋白可以被工程化以去除聚集的蛋白质并抑制慢性 ISR。
