Zhong Li, Zhao Weihong, Wu Jianqing, Li Baozheng, Zolotukhin Sergei, Govindasamy Lakshmanan, Agbandje-McKenna Mavis, Srivastava Arun
Division of Cellular and Molecular Therapy, Department of Pediatrics, University of Florida College of Medicine, Gainesville, Florida, USA.
Mol Ther. 2007 Jul;15(7):1323-30. doi: 10.1038/sj.mt.6300170. Epub 2007 Apr 17.
A 52 kd cellular protein, FK506-binding protein (FKBP52), phosphorylated at tyrosine residues by epidermal growth factor receptor protein tyrosine kinase (EGFR-PTK), inhibits adeno-associated virus 2 (AAV2) second-strand DNA synthesis and transgene expression. FKBP52 is dephosphorylated at tyrosine residues by T-cell protein tyrosine phosphatase (TC-PTP), and TC-PTP over-expression leads to improved viral second-strand DNA synthesis and improved transgene expression. In these studies, we observed that perturbation of EGFR-PTK signaling by a specific inhibitor, Tyrphostin 23 (Tyr23), augmented the transduction efficiency of the single-stranded AAV (ssAAV) vector as well as the self-complementary AAV (scAAV) vector. Similarly, tyrosine-dephosphorylation of FKBP52 by TC-PTP resulted in increased transduction by both vectors. These data suggested that EGFR-PTK signaling also affects aspects of AAV transduction other than viral second-strand DNA synthesis. We document that inhibition of EGFR-PTK signaling leads to decreased ubiquitination of AAV2 capsids which, in turn, facilitates nuclear transport by limiting proteasome-mediated degradation of AAV vectors. We also document that Tyr23-mediated increase in AAV2 transduction efficiency is not further enhanced by a specific proteasome inhibitor, MG132. Thus, EGFR-PTK signaling modulates ubiquitin (Ub)/proteasome pathway-mediated intracellular trafficking as well as FKBP52-mediated second-strand DNA synthesis of AAV2 vectors. This has implications in the optimal use of AAV vectors in gene therapy.
一种52千道尔顿的细胞蛋白,FK506结合蛋白(FKBP52),被表皮生长因子受体蛋白酪氨酸激酶(EGFR-PTK)在酪氨酸残基处磷酸化,可抑制腺相关病毒2(AAV2)的第二链DNA合成及转基因表达。FKBP52在酪氨酸残基处被T细胞蛋白酪氨酸磷酸酶(TC-PTP)去磷酸化,TC-PTP的过表达会导致病毒第二链DNA合成及转基因表达的改善。在这些研究中,我们观察到,一种特异性抑制剂酪氨酸磷酸化抑制剂23(Tyr23)对EGFR-PTK信号通路的干扰,增强了单链AAV(ssAAV)载体以及自我互补AAV(scAAV)载体的转导效率。同样,TC-PTP使FKBP52的酪氨酸去磷酸化导致两种载体的转导增加。这些数据表明,EGFR-PTK信号通路也影响AAV转导中除病毒第二链DNA合成之外的其他方面。我们证明,抑制EGFR-PTK信号通路会导致AAV2衣壳的泛素化减少,这反过来又通过限制蛋白酶体介导的AAV载体降解促进核转运。我们还证明,Tyr23介导的AAV2转导效率增加不会被特异性蛋白酶体抑制剂MG132进一步增强。因此,EGFR-PTK信号通路调节泛素(Ub)/蛋白酶体途径介导的细胞内运输以及FKBP52介导的AAV2载体第二链DNA合成。这对基因治疗中AAV载体的最佳使用具有重要意义。