The biological role of interferon y induced 65 kDa GBPs as effector molecules in host defense

干扰素γ (IFNγ)是一种促炎细胞因子，在抑制和清除感染中起着至关重要的作用。IFNγ激活许多基因的表达使应答细胞能够建立有效的抗菌效应系统，从而成功消除病原体或抑制复制。IFNγ诱导的一些效应分子目前已被表征；然而，对IFNγ介导的效应细胞的抗菌反应的理解仍然很大程度上是不完整的。特别是65kda的鸟苷酸结合蛋白（GBPs）被IFNγ大量诱导，但其功能仍然是谜。在我们最近的研究中，我们鉴定出了mGBP家族的6个新成员（mGBP 6、-7、-8、-9、-10和-11）。我们可以确定，mGBP家族的所有11个成员都是由IFNγ诱导的，并且在感染单核细胞增生乳杆菌和弓形虫后在小鼠中迅速诱导。值得注意的是，一些mGBPs （mGBP 1、-2、-3、-6、-7和-9）在弓形虫主动入侵后表现出亚细胞再分布和与寄生液泡的直接共定位。核苷酸结合基序的突变导致蛋白质在未感染细胞中的异常定位，并大大降低了重新定位到细胞内病原体的能力。在最后一个资助期，成功地产生了几种mGBPs （mGBP1, -2， -3和5）的基因缺陷小鼠。这些小鼠系是可存活的，将用于鉴定单个mGPBs的非冗余功能。我们已经证明mGBP1-/-胚胎成纤维细胞抑制弓形虫细胞内复制的能力显著降低。此外，mGBP 6、-7、-8、-9和-10的基因靶向正在进行中，本文提出了3号和5号染色体上mGBP基因簇的复合靶向。拟建项目的目的是表征mGBP蛋白对不同病原体的分子效应及其在体内防御细菌、病毒和寄生虫感染中的作用。

Interferon γ (IFNγ) is a proinflammatory cytokine which plays a crucial role in the containment and clearance of infections. The IFNγ activated expression of numerous genes enables responsive cells to establish potent antimicrobial effector systems, leading to successful pathogen elimination or inhibition of replication. Some effector molecules induced by IFNγ have been characterized so far; however, the understanding of the IFNγ mediated antimicrobial response of effector cells is still largely incomplete. In particular, the 65 kDa guanylate-binding proteins (GBPs) are abundantly induced by IFNγ, but their functions are still enigmatic. In our recent studies, we could identify 6 novel members of the mGBP family (mGBP 6, -7, -8, -9, -10, and -11). We could establish that all 11 members of the mGBP family are inducible by IFNγ and are rapidly induced in mice after infection with L. monocytogenes and T. gondii. Remarkably, several mGBPs (mGBP 1, -2, -3, -6, -7, and -9) show a subcellular redistribution and direct colocalization with the parasitophorous vacuole after active invasion of T. gondii parasites. Mutations of the nucleotide binding motifs lead to an aberrant localization of the proteins in uninfected cells and to a dramatically reduced capability to relocalize to intracellular pathogens. During the last funding period gene-deficient mice for several mGBPs (mGBP1, -2, -3, and 5) were successfully generated. These mouse lines are viable and will be employed to identify non-redundant functions of individual mGPBs. We could already demonstrate that mGBP1-/- embryonic fibroblasts show a significantly reduced capability to restrain the intracellular replication of T.gondii. Furthermore, gene targeting of mGBP 6, -7, -8, -9, and -10 is ongoing and the compound targeting of the mGBP gene clusters on chromosomes 3 and 5 are proposed here. The aim of the proposed project is the characterization of the molecular effects of the mGBP proteins on diverse pathogens and their in vivo role in the defence against bacterial, viral, and parasitic infections.