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AJP Cell Physiology
Article . 2011 . Peer-reviewed
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Small GTPase Rab11b regulates degradation of surface membrane L-type Cav1.2 channels

Authors: Jabe M, Best; Jason D, Foell; Courtney R, Buss; Brian P, Delisle; Ravi C, Balijepalli; Craig T, January; Timothy J, Kamp;

Small GTPase Rab11b regulates degradation of surface membrane L-type Cav1.2 channels

Abstract

L-type Ca2+ channels (LTCCs) play a critical role in Ca2+-dependent signaling processes in a variety of cell types. The number of functional LTCCs at the plasma membrane strongly influences the strength and duration of Ca2+ signals. Recent studies demonstrated that endosomal trafficking provides a mechanism for dynamic changes in LTCC surface membrane density. The purpose of the current study was to determine whether the small GTPase Rab11b, a known regulator of endosomal recycling, impacts plasmalemmal expression of Cav1.2 LTCCs. Disruption of endogenous Rab11b function with a dominant negative Rab11b S25N mutant led to a significant 64% increase in peak L-type Ba2+ current ( IBa,L) in human embryonic kidney (HEK)293 cells. Short-hairpin RNA (shRNA)-mediated knockdown of Rab11b also significantly increased peak IBa,L by 66% compared when with cells transfected with control shRNA, whereas knockdown of Rab11a did not impact IBa,L. Rab11b S25N led to a 1.7-fold increase in plasma membrane density of hemagglutinin epitope-tagged Cav1.2 expressed in HEK293 cells. Cell surface biotinylation experiments demonstrated that Rab11b S25N does not significantly impact anterograde trafficking of LTCCs to the surface membrane but rather slows degradation of plasmalemmal Cav1.2 channels. We further demonstrated Rab11b expression in ventricular myocardium and showed that Rab11b S25N significantly increases peak IBa,L by 98% in neonatal mouse cardiac myocytes. These findings reveal a novel role for Rab11b in limiting, rather than promoting, the plasma membrane expression of Cav1.2 LTCCs in contrast to its effects on other ion channels including human ether-a-go-go-related gene (hERG) K+ channels and cystic fibrosis transmembrane conductance regulator. This suggests Rab11b differentially regulates the trafficking of distinct cargo and extends our understanding of how endosomal transport impacts the functional expression of LTCCs.

Keywords

Calcium Channels, L-Type, Electrophysiological Phenomena, Mice, Protein Transport, HEK293 Cells, Barium, rab GTP-Binding Proteins, Mutation, Animals, Humans, Biotinylation, Myocytes, Cardiac, RNA, Small Interfering, Cells, Cultured, Monomeric GTP-Binding Proteins

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    This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
    Top 10%
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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
33
Top 10%
Top 10%
Top 10%
bronze