KV10.1 K(+)-channel plasma membrane discrete domain partitioning and its functional correlation in neurons

Abstract

KV10.1 potassium channels are implicated in a variety of cellular processes including cell proliferation and tumour progression. Their expression in over 70% of human tumours makes them an attractive diagnostic and therapeutic target. Although their physiological role in the central nervous system is not yet fully understood, advances in their precise cell localization will contribute to the understanding of their interactions and function. We have determined the plasma membrane (PM) distribution of the KV10.1 protein in an enriched mouse brain PM fraction and its association with cholesterol- and sphingolipid-rich domains. We show that the KV10.1 channel has two different populations in a 3:2 ratio, one associated to and another excluded from Detergent Resistant Membranes (DRMs). This distribution of KV10.1 in isolated PM is cholesterol- and cytoskeleton-dependent since alteration of those factors changes the relationship to 1:4. In transfected HEK-293 cells with a mutant unable to bind Ca(2+)/CaM to KV10.1 protein, Kv10.1 distribution in DRM/non-DRM is 1:4. Mean current density was doubled in the cholesterol-depleted cells, without any noticeable effects on other parameters. These results demonstrate that recruitment of the KV10.1 channel to the DRM fractions involves its functional regulation.

Keywords: Alf1; BTX; Ca-CaM; CaMKII; Cav-1; Cholesterol; Cyclodextrin; DRM; Eag1; Flot-2; GM1; GM130; GalCer; Gfap; Golgi marker 130; HERG; HIF; K(V)10.1; LPR-1; Lat-A; MBP; Membrane; Olig2; PLP; PM; RSA; SNARE; Soluble NSF Attachment Protein; Syn; TCA; TRAPα; TfR; allograft inflammatory factor1; bungarotoxin; calcium calmodulin; calcium calmodulin kinase II; caveolin-1; detergent resistant membrane; flotilin-2; galactosylceramide; glial fibrillary acidic protein; human EAG related gene, HEK, human embryonic kidney; hypoxia inducible factor; latrunculin A; lipoprotein receptor-1; monosialotetrahexosylganglioside1; myelin basic protein; oligodendrocyte transcription factor2, Mtap1, microtubule associated protein1; plasma membrane; proteolipid protein; relative specific activity; synaptophysin; transferrin receptor; translocon associated protein alpha; trichloroacetic acid.