In Vitro Анализ PDZ-зависимый CFTR высокомолекулярных комплексов сигнализации
Summary
Муковисцидоз трансмембранной проводимости регулятора (CFTR), эпителиальный канал хлорид, как сообщается, взаимодействуют с различными белками и регулировать важные клеточные процессы, среди которых CFTR PDZ мотив-опосредованного взаимодействия были хорошо документированы. Этот протокол описывает методы, которые мы разработали, чтобы собрать PDZ-зависимый CFTR макромолекулярных сигнализации комплекс<em> В пробирке</em>.
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel located primarily at the apical membranes of epithelial cells, plays a crucial role in transepithelial fluid homeostasis1-3. CFTR has been implicated in two major diseases: cystic fibrosis (CF)4 and secretory diarrhea5. In CF, the synthesis or functional activity of the CFTR Cl- channel is reduced. This disorder affects approximately 1 in 2,500 Caucasians in the United States6. Excessive CFTR activity has also been implicated in cases of toxin-induced secretory diarrhea (e.g., by cholera toxin and heat stable E. coli enterotoxin) that stimulates cAMP or cGMP production in the gut7.
Accumulating evidence suggest the existence of physical and functional interactions between CFTR and a growing number of other proteins, including transporters, ion channels, receptors, kinases, phosphatases, signaling molecules, and cytoskeletal elements, and these interactions between CFTR and its binding proteins have been shown to be critically involved in regulating CFTR-mediated transepithelial ion transport in vitro and also in vivo8-19. In this protocol, we focus only on the methods that aid in the study of the interactions between CFTR carboxyl terminal tail, which possesses a protein-binding motif [referred to as PSD95/Dlg1/ZO-1 (PDZ) motif], and a group of scaffold proteins, which contain a specific binding module referred to as PDZ domains. So far, several different PDZ scaffold proteins have been reported to bind to the carboxyl terminal tail of CFTR with various affinities, such as NHERF1, NHERF2, PDZK1, PDZK2, CAL (CFTR-associated ligand), Shank2, and GRASP20-27. The PDZ motif within CFTR that is recognized by PDZ scaffold proteins is the last four amino acids at the C terminus (i.e., 1477-DTRL-1480 in human CFTR)20. Interestingly, CFTR can bind more than one PDZ domain of both NHERFs and PDZK1, albeit with varying affinities22. This multivalency with respect to CFTR binding has been shown to be of functional significance, suggesting that PDZ scaffold proteins may facilitate formation of CFTR macromolecular signaling complexes for specific/selective and efficient signaling in cells16-18.
Multiple biochemical assays have been developed to study CFTR-involving protein interactions, such as co-immunoprecipitation, pull-down assay, pair-wise binding assay, colorimetric pair-wise binding assay, and macromolecular complex assembly assay16-19,28,29. Here we focus on the detailed procedures of assembling a PDZ motif-dependent CFTR-containing macromolecular complex in vitro, which is used extensively by our laboratory to study protein-protein or domain-domain interactions involving CFTR16-19,28,29.
Protocol
Discussion
В этом протоколе мы показали метод в пробирке сборки и обнаружения CFTR содержащие высокомолекулярные сигнализации комплексного использования очищенных белков (или фрагменты белка) и / или клеточных лизатов, как сообщалось ранее 16-19,29,30. Для достижения наилучших результатов с…
Divulgations
The authors have nothing to disclose.
Acknowledgements
Наша работа была поддержана грантами от Американской ассоциации сердца (Большой Юго-Восточной Партнерская) Начало-грантов в помощь 0765185B, Эльза У. Парди фонда грант, и Wayne State University очной запуске фонда и научно-исследовательского института сердечно-сосудистой Isis инициативы награду. Этот метод экстракорпорального CFTR сборки сложных высокомолекулярных изначально первым доктором AP Naren (Университет Теннесси Научного центра здоровья).
Materials
| Name of the reagent | Company | Catalog number | Comments |
| pGEX4T-1 vector | GE Healthcare | 28-9545-49 | formerly Amersham Biosciences |
| pMAL-C2 vector | New England BioLabs | ||
| pET30 vector | EMD Chemicals | 69077-3 | formerly Novagen |
| Glutathione agarose beads | BD Biosciences | 554780 | |
| Amylose resin | New England BioLabs | E8021S | |
| Talon beads | Clontech | 635501 | |
| reduced glutathione | BD Biosciences | 554782 | |
| imidazole | Fisher | BP305-50 | |
| maltose | Fisher | BP684-500 | |
| S-protein agarose | EMD Chemicals | 69704-3 | formerly Novagen |
| Anti-Flag HRP | Sigma | A8592 | |
| Anti-CFTR IgG | Custom-made | R1104 | mAb recognizing CFTR epitope at a.a. 722-734 |
| Anti-MRP2 IgG | Chemicon International | MAB4148 | Now a part of Millipore |
Table 2. Specific reagents and equipment.
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