title: Potassium-chloride cotransporter 3 interacts with Vav2 to synchronize the cell volume decrease response with cell protrusion dynamics.
abstract: Loss-of-function of the potassium-chloride cotransporter 3 (KCC3) causes hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC), a severe neurodegenerative disease associated with defective midline crossing of commissural axons in the brain. Conversely, KCC3 over-expression in breast, ovarian and cervical cancer is associated with enhanced tumor cell malignancy and invasiveness. We identified a highly conserved proline-rich sequence within the C-terminus of the cotransporter which when mutated leads to loss of the KCC3-dependent regulatory volume decrease (RVD) response in Xenopus Laevis oocytes. Using SH3 domain arrays, we found that this poly-proline motif is a binding site for SH3-domain containing proteins in vitro. This approach identified the guanine nucleotide exchange factor (GEF) Vav2 as a candidate partner for KCC3. KCC3/Vav2 physical interaction was confirmed using GST-pull down assays and immuno-based experiments. In cultured cervical cancer cells, KCC3 co-localized with the active form of Vav2 in swelling-induced actin-rich protruding sites and within lamellipodia of spreading and migrating cells. These data provide evidence of a molecular and functional link between the potassium-chloride co-transporters and the Rho GTPase-dependent actin remodeling machinery in RVD, cell spreading and cell protrusion dynamics, thus providing new insights into KCC3's involvement in cancer cell malignancy and in corpus callosum agenesis in HMSN/ACC.
authors.affiliation: Centre of Excellence in Neuroscience of University of Montreal, Montréal, Québec, Canada.
authors.forename: Adèle
authors.initials: A
authors.lastname: Salin-Cantegrel
authors.forename: Masoud
authors.initials: M
authors.lastname: Shekarabi
authors.forename: Sarah
authors.initials: S
authors.lastname: Rasheed
authors.forename: François M
authors.initials: FM
authors.lastname: Charron
authors.forename: Janet
authors.initials: J
authors.lastname: Laganière
authors.forename: Rebecca
authors.initials: R
authors.lastname: Gaudet
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Dion
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Lapointe
authors.forename: Guy A
authors.initials: GA
authors.lastname: Rouleau
mesh_terms: D000199:Actins / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D048429:Cell Size / Q000187:drug effects; D022081:Cell Surface Extensions / Q000187:drug effects / Q000378:metabolism*; D017124:Conserved Sequence; D006367:HeLa Cells; D006801:Humans; D007038:Hypotonic Solutions / Q000494:pharmacology; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D051567:Proto-Oncogene Proteins c-vav / Q000378:metabolism*; D027981:Symporters / Q000737:chemistry / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D000199:Actins; D007038:Hypotonic Solutions; D050505:Mutant Proteins; D051567:Proto-Oncogene Proteins c-vav; D027981:Symporters; C093651:VAV2 protein, human