title: Regulation of epithelial ion channels by Rab GTPases.
abstract: Epithelial ion channels are crucial to many of life's processes and disruption of their functions can lead to several disorders. Cystic fibrosis, an autosomal recessive disorder, is caused by defects in the biosynthesis or function of the CFTR chloride channel. Similarly, mutations in certain ENaC genes leading to increased or reduced channel activity cause diseases such as Liddle's syndrome or PHA. In order for ion channel proteins to be functional they need to be expressed on the plasma membrane. Thus, molecules that modulate the trafficking of ion channels to and from the membrane are of utmost significance. Among the numerous factors that regulate their functioning is a family of small GTPases known as Rab proteins. While Rabs have always played a pivotal role in membrane trafficking, their diversity of functions and plethora of interacting partners have lately been brought to light. Recent studies reveal that multiple Rab isoforms physically interact with and/or modulate the activity of several ion channels. Rab proteins have the ability to serve as molecular switches and many of the ion channels are regulated differentially by the GTP- or GDP-bound Rab isoforms. This review examines the role of Rab GTPases in the trafficking of ion channels, including CFTR, ENaC, TRPV5/6, and aquaporins, based on recent evidence.
authors.affiliation: Center for Cell and Molecular Biology, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, NJ 07030, USA. ssaxena@stevens.edu
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Saxena
authors.forename: Simarna
authors.initials: S
authors.lastname: Kaur
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism*; D004847:Epithelial Cells / Q000502:physiology*; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D005246:Feedback / Q000502:physiology; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D008954:Models, Biological; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D015220:Calcium Channels; D053503:Epithelial Sodium Channels; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D020691:rab GTP-Binding Proteins