KCNJ15/Kir4.2 couples with polyamines to sense weak extracellular electric fields in galvanotaxis

• Published in: Nature communications 2015-10, Vol.6 (1), p.8532-8532, Article 8532
• Main Authors: Nakajima, Ken-ichi, Zhu, Kan, Sun, Yao-Hui, Hegyi, Bence, Zeng, Qunli, Murphy, Christopher J., Small, J. Victor, Chen-Izu, Ye, Izumiya, Yoshihiro, Penninger, Josef M., Zhao, Min
• Format: Article
• Language: English
• Subjects: 13/109; 13/89; 14/1; 14/34; 14/63; 38/77; 631/45/269; 631/57/2270/1140; 631/80/84; 82/51; 9/74; Cell adhesion & migration; Cell Line, Tumor; Cell migration; Coupling (molecular); Defective mutant; Depletion; Electric fields; Electricity; Humanities and Social Sciences; Humans; Ion Transport; multidisciplinary; Phosphatidylinositol 3,4,5-triphosphate; Polyamines; Polyamines - metabolism; Potassium channels; Potassium channels (inwardly-rectifying); Potassium Channels, Inwardly Rectifying - genetics; Potassium Channels, Inwardly Rectifying - metabolism; RNA-mediated interference; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms9532

Weak electric fields guide cell migration, known as galvanotaxis/electrotaxis. The sensor(s) cells use to detect the fields remain elusive. Here we perform a large-scale screen using an RNAi library targeting ion transporters in human cells. We identify 18 genes that show either defective or increased galvanotaxis after knockdown. Knockdown of the KCNJ15 gene (encoding inwardly rectifying K + channel Kir4.2) specifically abolishes galvanotaxis, without affecting basal motility and directional migration in a monolayer scratch assay. Depletion of cytoplasmic polyamines, highly positively charged small molecules that regulate Kir4.2 function, completely inhibits galvanotaxis, whereas increase of intracellular polyamines enhances galvanotaxis in a Kir4.2-dependent manner. Expression of a polyamine-binding defective mutant of KCNJ15 significantly decreases galvanotaxis. Knockdown or inhibition of KCNJ15 prevents phosphatidylinositol 3,4,5-triphosphate (PIP 3 ) from distributing to the leading edge. Taken together these data suggest a previously unknown two-molecule sensing mechanism in which KCNJ15 /Kir4.2 couples with polyamines in sensing weak electric fields. Directed cell migration in weak electric fields is known as galvanotaxis, but the cellular sensor and mechanism is not known. Here Nakajima et al. identify inwardly rectifying K + channel Kir4.2 as an important mediator of galvanotaxis, that depends on the cytoplasmic distribution of intracellular polyamines.