Analysis of the ISG15 conjugation and deconjugation system in vivo

干扰素刺激基因15(ISG15)的蛋白质修饰是由特异的E1激活酶Ube1L、E2连接酶UbCH8和HERC5作为主要的人类E3连接酶介导的。半胱氨酸蛋白酶UBP43可以抑制ISG化，据报道它参与了多种生物学过程，如天然免疫、病毒防御和控制恶性增殖。我们确定mHERC6是主要的小鼠ISG15 E3连接酶，目前建立了条件基因敲除小鼠来分析该蛋白在体内的功能。为了评估ISG15去结合的作用，我们建立了UBP43异肽酶活性被特异性灭活的小鼠。因此，ISG化水平提高，伴随着对病毒感染的更高抵抗力。我们将继续分析这些小鼠，以确定ISG15去卷曲的作用，从而评估UBP43治疗抑制的可能性。为了研究分子功能，新的UBP43相互作用伙伴被确定并将被分析。

Protein modification by the Interferon Stimulated Gene 15 (ISG15) is mediated by the specific E1 activating enzyme Ube1L, the E2 ligase UbCH8 and HERC5 as the major human E3 ligase. ISGylation is counteracted by the cysteine protease UBP43 and reported to be involved in multiple biological processes like innate immunity, viral defence and the control of malignant proliferation. We identified mHERC6 as the major murine ISG15 E3 ligase and currently generate conditional knockout mice to analyze the function of this protein in vivo. To evaluate the role of ISG15 deconjugation we generated mice where the isopeptidase activity of UBP43 was specifically inactivated. As a consequence levels of ISGylation are enhanced, accompanied by higher resistance to viral infection. We will continue to analyze these mice to determine the role of ISG15 deconjugation and thus evaluate the potential for therapeutic inhibition of UBP43. To investigate molecular functions, new UBP43 interaction partners were identified and will be analyzed.