Riazanski Vladimir, Gabdoulkhakova Aida G, Boynton Lin S, Eguchi Raphael R, Deriy Ludmila V, Hogarth D Kyle, Loaëc Nadège, Oumata Nassima, Galons Hervé, Brown Mary E, Shevchenko Pavel, Gallan Alexander J, Yoo Sang Gune, Naren Anjaparavanda P, Villereal Mitchel L, Beacham Daniel W, Bindokas Vytautas P, Birnbaumer Lutz, Meijer Laurent, Nelson Deborah J
Department of Pharmacological and Physiological Sciences and Department of Medicine, University of Chicago, Chicago, IL 60637;
Department of Research and Development, ManRos Therapeutics, Hôtel de Recherche, Centre de Perharidy, 29680 Roscoff, France;
Proc Natl Acad Sci U S A. 2015 Nov 24;112(47):E6486-95. doi: 10.1073/pnas.1518966112. Epub 2015 Nov 10.
Defects in the innate immune system in the lung with attendant bacterial infections contribute to lung tissue damage, respiratory insufficiency, and ultimately death in the pathogenesis of cystic fibrosis (CF). Professional phagocytes, including alveolar macrophages (AMs), have specialized pathways that ensure efficient killing of pathogens in phagosomes. Phagosomal acidification facilitates the optimal functioning of degradative enzymes, ultimately contributing to bacterial killing. Generation of low organellar pH is primarily driven by the V-ATPases, proton pumps that use cytoplasmic ATP to load H(+) into the organelle. Critical to phagosomal acidification are various channels derived from the plasma membrane, including the anion channel cystic fibrosis transmembrane conductance regulator, which shunt the transmembrane potential generated by movement of protons. Here we show that the transient receptor potential canonical-6 (TRPC6) calcium-permeable channel in the AM also functions to shunt the transmembrane potential generated by proton pumping and is capable of restoring microbicidal function to compromised AMs in CF and enhancement of function in non-CF cells. TRPC6 channel activity is enhanced via translocation to the cell surface (and then ultimately to the phagosome during phagocytosis) in response to G-protein signaling activated by the small molecule (R)-roscovitine and its derivatives. These data show that enhancing vesicular insertion of the TRPC6 channel to the plasma membrane may represent a general mechanism for restoring phagosome activity in conditions, where it is lost or impaired.
肺部先天性免疫系统缺陷伴随细菌感染，在囊性纤维化（CF）的发病机制中导致肺组织损伤、呼吸功能不全，并最终导致死亡。包括肺泡巨噬细胞（AM）在内的专职吞噬细胞具有专门的途径，可确保在吞噬小体中有效杀灭病原体。吞噬体酸化有助于降解酶的最佳功能，最终有助于杀灭细菌。低细胞器pH的产生主要由V-ATP酶驱动，V-ATP酶是利用细胞质ATP将H(+)加载到细胞器中的质子泵。对吞噬体酸化至关重要的是源自质膜的各种通道，包括阴离子通道囊性纤维化跨膜传导调节因子，它可分流质子移动产生的跨膜电位。在这里，我们表明AM中的瞬时受体电位经典型6（TRPC6）钙通透性通道也具有分流质子泵产生的跨膜电位的功能，并且能够恢复CF中受损AM的杀菌功能，并增强非CF细胞的功能。响应小分子（R）-roscovitine及其衍生物激活的G蛋白信号，TRPC6通道活性通过易位到细胞表面（然后在吞噬过程中最终易位到吞噬体）而增强。这些数据表明，增强TRPC6通道向质膜的囊泡插入可能代表了一种在吞噬体活性丧失或受损的情况下恢复其活性的普遍机制。
