Dataset Information

Regulation of ?-adrenergic receptor trafficking and lung microvascular endothelial cell permeability by Rab5 GTPase.

ABSTRACT: Rab5 GTPase modulates the trafficking of the cell surface receptors, including G protein-coupled ?-adrenergic receptors (?-ARs). Here, we have determined the role of Rab5 in regulating the internalization of ?-ARs in lung microvascular endothelial cells (LMECs) and in maintaining the integrity and permeability of endothelial cell barrier. Our data demonstrate that lipopolysaccharide (LPS) treatment disrupts LMEC barrier function and reduces the cell surface expression of ?-ARs. Furthermore, the activation of ?-ARs, particularly ?2-AR, is able to protect the LMEC permeability from LPS injury. Moreover, siRNA-mediated knockdown of Rab5 inhibits both the basal and agonist-provoked internalization of ?-ARs, therefore, enhancing the cell surface expression of the receptors and receptor-mediated ERK1/2 activation. Importantly, knockdown of Rab5 not only inhibits the LPS-induced effects on ?-ARs but also protects the LMEC monolayer permeability. All together, these data provide strong evidence indicating a crucial role of Rab5-mediated internalization of ?-ARs in functional regulation of LMECs.

SUBMITTER: Yang J

PROVIDER: S-EPMC4495405 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Regulation of β-adrenergic receptor trafficking and lung microvascular endothelial cell permeability by Rab5 GTPase.

Yang Junjun J Sun Huan H Zhang Jihang J Hu Mingdong M Wang Jianchun J Wu Guangyu G Wang Guansong G

International journal of biological sciences 20150601 8

Rab5 GTPase modulates the trafficking of the cell surface receptors, including G protein-coupled β-adrenergic receptors (β-ARs). Here, we have determined the role of Rab5 in regulating the internalization of β-ARs in lung microvascular endothelial cells (LMECs) and in maintaining the integrity and permeability of endothelial cell barrier. Our data demonstrate that lipopolysaccharide (LPS) treatment disrupts LMEC barrier function and reduces the cell surface expression of β-ARs. Furthermore, the ...[more]

PMID: 26157342

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Project description:The number and activity of Cav1.2 channels in the cardiomyocyte sarcolemma tunes the magnitude of Ca2+-induced Ca2+ release and myocardial contraction. β-Adrenergic receptor (βAR) activation stimulates sarcolemmal insertion of CaV1.2. This supplements the preexisting sarcolemmal CaV1.2 population, forming large "superclusters" wherein neighboring channels undergo enhanced cooperative-gating behavior, amplifying Ca2+ influx and myocardial contractility. Here, we determine this stimulated insertion is fueled by an internal reserve of early and recycling endosome-localized, presynthesized CaV1.2 channels. βAR-activation decreased CaV1.2/endosome colocalization in ventricular myocytes, as it triggered "emptying" of endosomal CaV1.2 cargo into the t-tubule sarcolemma. We examined the rapid dynamics of this stimulated insertion process with live-myocyte imaging of channel trafficking, and discovered that CaV1.2 are often inserted into the sarcolemma as preformed, multichannel clusters. Similarly, entire clusters were removed from the sarcolemma during endocytosis, while in other cases, a more incremental process suggested removal of individual channels. The amplitude of the stimulated insertion response was doubled by coexpression of constitutively active Rab4a, halved by coexpression of dominant-negative Rab11a, and abolished by coexpression of dominant-negative mutant Rab4a. In ventricular myocytes, βAR-stimulated recycling of CaV1.2 was diminished by both nocodazole and latrunculin-A, suggesting an essential role of the cytoskeleton in this process. Functionally, cytoskeletal disruptors prevented βAR-activated Ca2+ current augmentation. Moreover, βAR-regulation of CaV1.2 was abolished when recycling was halted by coapplication of nocodazole and latrunculin-A. These findings reveal that βAR-stimulation triggers an on-demand boost in sarcolemmal CaV1.2 abundance via targeted Rab4a- and Rab11a-dependent insertion of channels that is essential for βAR-regulation of cardiac CaV1.2.

Dataset Information

Regulation of ?-adrenergic receptor trafficking and lung microvascular endothelial cell permeability by Rab5 GTPase.

Publications

Regulation of β-adrenergic receptor trafficking and lung microvascular endothelial cell permeability by Rab5 GTPase.

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