Cell permeable ITAM constructs for the modulation of mediator release in mast cells
作者:Joeri Kuil、Marcel J. E. Fischer、Nico J. de Mol、Rob M. J. Liskamp
DOI:10.1039/c0ob00441c
日期:——
Spleen tyrosine kinase (Syk) is essential for high affinity IgE receptor (FcεRI) mediated mast cell degranulation. Once FcεRI is stimulated, intracellular ITAM motifs of the receptor are diphosphorylated (dpITAM) and Syk is recruited to the receptor by binding of the Syk tandem SH2 domain to dpITAM, resulting in activation of Syk and, eventually, degranulation. To investigate intracellular effects of ITAM mimics, constructs were synthesized with ITAM mimics conjugated to different cell penetrating peptides, i.e. Tat, TP10, octa-Arg and K(Myr)KKK, or a lipophilic C12-chain. In most constructs the cargo and carrier were linked to each other through a disulfide bridge, which is convenient for combining different cargos with different carriers and has the advantage that the cargo and the carrier may be separated by reduction of the disulfide once it is intracellular. The ability of these ITAM constructs to label RBL-2H3 cells was assessed using flow cytometry. Fluorescence microscopy showed that the octa-Arg-SS-Flu-ITAM construct was present in various parts of the cells, although it was not homogeneously distributed. In addition, cell penetrating constructs without fluorescent labels were synthesized to examine degranulation in RBL-2H3 cells. Octa-Arg-SS-ITAM stimulated the mediator release up to 140%, indicating that ITAM mimics may have the ability to activate non-receptor bound Syk.
脾酪氨酸激酶(Syk)对高亲和力IgE受体(FcεRI)介导的肥大细胞脱颗粒至关重要。一旦FcεRI被刺激,受体的细胞内ITAM基序会发生双磷酸化(dpITAM),Syk通过其SH2二聚体与dpITAM结合被招募到受体上,导致Syk的激活,并最终导致脱颗粒。为了研究ITAM模仿物的细胞内效应,合成了与不同细胞穿透肽结合的ITAM模仿物构建体,即Tat、TP10、八铵和K(Myr)KKK,或一个亲脂性的C12链。在大多数构建体中,载荷与载体通过二硫化物桥连接,这便于将不同的载荷与不同的载体结合,并且具有优点,即载荷和载体可以在细胞内通过还原二硫化物分开。这些ITAM构建体对RBL-2H3细胞的标记能力通过流式细胞术进行评估。荧光显微镜显示,八铵-SS-Flu-ITAM构建体存在于细胞的多个部分,尽管分布并不均匀。此外,还合成了没有荧光标签的细胞穿透构建体,以检查RBL-2H3细胞的脱颗粒。八铵-SS-ITAM刺激介质释放增加了140%,表明ITAM模仿物可能具有激活非受体结合的Syk的能力。