Weigel-Kelley Kirsten A, Yoder Mervin C, Chen Linyuan, Srivastava Arun
Division of Cellular and Molecular Therapy, Department of Pediatrics, Powell Gene Therapy Center, University of Florida College of Medicine, Gainesville, FL 32610, USA.
Hum Gene Ther. 2006 Sep;17(9):909-20. doi: 10.1089/hum.2006.17.909.
Most viral vectors used for gene therapy lack the ability to target a defined cell population. Parvovirus B19 has a restricted tropism for human erythroid progenitor cells and uses activated alpha5beta1 integrins as coreceptors for entry [Weigel-Kelley, K.A., Yoder, M.C., and Srivastava, A. (2003). Blood 102, 3927-3933]. In this study we examined the role of coexpressed integrins in alpha5beta1 integrin coreceptor function. Antibody-mediated cross-linking of beta1, beta2, and beta3 integrins and the integrin-associated protein (IAP) increased parvovirus B19 entry into nontarget K562 cells. Functional silencing of one integrin group, however, reduced the virus uptake- promoting function of a subsequently activated integrin group, indicating that the three integrins did not operate in isolation but through shared signaling pathways. This was further corroborated by direct competition between simultaneously clustered beta2 and beta1 integrins that could be overcome by stabilizing clustered beta1 integrins in a high-affinity conformation. In contrast, parvovirus B19 entry into primary erythroid progenitor cells was characterized by strong clustering-induced beta1 integrin coreceptor activity that was not abolished by subsequent beta2 and beta3 integrin activation and was, in fact, substantially increased in the presence of preclustered beta2 and beta3 integrins. Thus, integrin function is regulated in a cell type-specific manner through coexpressed integrins and preferential parvovirus B19 entry into erythroid progenitor cells is promoted by a robust beta1 integrin response that is enhanced through stable preclustering of coexpressed integrins. These results have implications for other viral vectors that use integrins as receptors/coreceptors and for gene therapy of hematopoietic progenitor cells using parvovirus B19 vectors.
大多数用于基因治疗的病毒载体缺乏靶向特定细胞群体的能力。细小病毒B19对人类红系祖细胞具有受限的嗜性，并利用活化的α5β1整合素作为进入的共受体[Weigel-Kelley, K.A., Yoder, M.C., and Srivastava, A. (2003). Blood 102, 3927 - 3933]。在本研究中，我们检测了共表达的整合素在α5β1整合素共受体功能中的作用。抗体介导的β1、β2和β3整合素以及整合素相关蛋白（IAP）的交联增加了细小病毒B19进入非靶K562细胞的能力。然而，一个整合素组的功能沉默降低了随后活化的整合素组促进病毒摄取的功能，这表明这三种整合素并非独立发挥作用，而是通过共享的信号通路起作用。同时聚集的β2和β1整合素之间的直接竞争进一步证实了这一点，这种竞争可通过将聚集的β1整合素稳定在高亲和力构象中得以克服。相反，细小病毒B19进入原代红系祖细胞的特征是强烈的聚集诱导的β1整合素共受体活性，随后的β2和β3整合素活化并不能消除这种活性，事实上，在预先聚集的β2和β3整合素存在的情况下，这种活性会显著增加。因此，整合素功能通过共表达的整合素以细胞类型特异性的方式受到调节，并且通过共表达整合素的稳定预先聚集增强的强大β1整合素反应促进了细小病毒B19优先进入红系祖细胞。这些结果对其他使用整合素作为受体/共受体的病毒载体以及使用细小病毒B19载体对造血祖细胞进行基因治疗具有启示意义。
