title: Rab27a GTPase modulates L-type Ca2+ channel function via interaction with the II-III linker of CaV1.3 subunit.
abstract: In a variety of cells, secretory processes require the activation of both Rab27a and L-type channels of the Ca(V)1.3 subtype. In the retinal pigment epithelium (RPE), Rab27a and Ca(V)1.3 channels regulate growth-factor secretion towards its basolateral side. Analysis of murine retina sections revealed a co-localization of both Rab27a and Ca(V)1.3 at the basolateral membrane of the RPE. Heterologously expressed Ca(V)1.3/β3/α2δ1 channels showed negatively shifted voltage-dependence and decreased current density of about 70% when co-expressed with Rab27a. However, co-localization analysis using α(5)β(1) integrin as a membrane marker revealed that Rab27a co-expression reduced the surface expression of Ca(V)1.3 only about 10%. Physical binding of heterologously expressed Rab27a with Ca(V)1.3 channels was shown by co-localization in immunocytochemistry as well as co-immunoprecipitation which was abolished after deletion of a MyRIP-homologous amino acid sequence at the II-III linker of the Ca(V)1.3 subunit. Rab27a over-expression in ARPE-19 cells positively shifted the voltage dependence, decreased current density of endogenous Ca(V)1.3 channels and reduced VEGF-A secretion. We show the first evidence of a direct functional modulation of an ion channel by Rab27a suggesting a new mechanism of Rab and ion channel interaction in the control of VEGF-A secretion in the RPE.
authors.affiliation: Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany; Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Reichhart
authors.affiliation: Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Markowski
authors.affiliation: Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany.
authors.forename: Shimpei
authors.initials: S
authors.lastname: Ishiyama
authors.affiliation: Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Wagner
authors.affiliation: Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany.
authors.forename: Sergio
authors.initials: S
authors.lastname: Crespo-Garcia
authors.affiliation: Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany.
authors.forename: Talitha
authors.initials: T
authors.lastname: Schorb
authors.affiliation: CEDOC, Faculdade de Ciências Médicas (FCM), Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: José S
authors.initials: JS
authors.lastname: Ramalho
authors.affiliation: Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany; Department of Psychiatry and Psychotherapy, Molecular Neuroscience, University of Regensburg, Germany.
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Milenkovic
authors.affiliation: Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Föckler
authors.affiliation: CEDOC, Faculdade de Ciências Médicas (FCM), Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: Miguel C
authors.initials: MC
authors.lastname: Seabra
authors.affiliation: Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany; Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany. Electronic address: olaf.strauss@charite.de.
authors.forename: Olaf
authors.initials: O
authors.lastname: Strauß
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D015220:Calcium Channels / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002460:Cell Line; D003412:Cricetulus; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018408:Patch-Clamp Techniques; D017434:Protein Structure, Tertiary; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000075745:rab27 GTP-Binding Proteins
chemical_list: C512066:CACNA2D1 protein, mouse; C485995:Cacna1d protein, mouse; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D042461:Vascular Endothelial Growth Factor A; D000075745:rab27 GTP-Binding Proteins; C512962:Rab27a protein, mouse; D020691:rab GTP-Binding Proteins
keywords: Ca(v)1.3; MyRIP; Protein interaction; Rab GTPase; Rab27a; Voltage dependence