Molecular Determinants of Kv1.3 Potassium Channels-induced Proliferation

Abstract

Changes in voltage-dependent potassium channels (Kv channels) associate to proliferation in many cell types, including transfected HEK293 cells. In this system Kv1.5 overexpression decreases proliferation, whereas Kv1.3 expression increases it independently of K ؉ fluxes. To identify Kv1.3 domains involved in a proliferation-associated signaling mechanism(s), we constructed chimeric Kv1.3-Kv1.5 channels and point-mutant Kv1.3 channels, which were expressed as GFP-or cherry-fusion proteins. We studied their trafficking and functional expression, combining immunocytochemical and electrophysiological methods, and their impact on cell proliferation. We found that the C terminus is necessary for Kv1.3-induced proliferation. We distinguished two residues (Tyr-447 and Ser-459) whose mutation to alanine abolished proliferation. The insertion into Kv1.5 of a sequence comprising these two residues increased proliferation rate. Moreover, Kv1.3 voltage-dependent transitions from closed to open conformation induced MEK-ERK1/2-dependent Tyr-447 phosphorylation. We conclude that the mechanisms for Kv1.3-induced proliferation involve the accessibility of key docking sites at the C terminus. For one of these sites (Tyr-447) we demonstrated the contribution of MEK/ERK-dependent phosphorylation, which is regulated by voltage-induced conformational changes.

Ionic immune suppression within the tumour microenvironment limits T cell effector function

“…Packaging cells were transfected with 20µg of retroviral plasmid DNA encoding MSGV-Thy1.1, MSGV- Kcna3 -Thy1.1, MSGV- Kcna3 -Thy1.1 (W389F) (referred to as Kcna3_PD ) 25, 40, MSGV- Ppp2r1a (K416E) -Thy1.1 (referred to as PP2A_DN41,42), MSCV-IRES-Thy1.1 (pMIT), or pMIT Akt1- CA43 where indicated along with 6µg pCL-Eco plasmid DNA using 60µL Lipofectamine 2000 in OptiMEM (Invitrogen) for 8 hours in antibiotic-free media. Media was replaced 8h after transfection and cells were incubated for a further 48 hours.…”

Human immunodeficiency virus protein Tat induces oligodendrocyte injury by enhancing outward K+ current conducted by KV1.3

“…K V 1.3 is positively associated with apoptosis in different types of cells, including retinal ganglion cell (Jimenez-Perez et al, 2016), lymphocytes (Bock et al, 2002; Valencia-Cruz et al, 2009), and various cancer cells (Abdul and Hoosein, 2006; Brevet et al, 2008; Brevet et al, 2009). In agreement with these studies, our results showed Tat-induced apoptosis in cultured Ols was attenuated either by knockdown K V 1.3 gene or by specific K V 1.3 antagonists, but not by a K V 2.1 antagonist (Fig.…”

Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth

“…Studies in human VSM cells also confirm a role for K V 1.3 in proliferation (Cheong et al, 2011; Cidad et al, 2015). Interestingly, K V 1.3 may contribute to VSM proliferation by ion-permeation-independent mechanisms (Cidad et al, 2012; Cidad et al, 2015; Jimenez-Perez et al, 2016). The pro-proliferative effects of K V 1.3 are mediated by voltage-dependent exposure of key residues in the channel’s C-terminus (Tyr-447 and Ser-459) (Jimenez-Perez et al, 2016).…”

“…H. Liu et al, 2009; Mahaut-Smith, Martinez-Pinna, & Gurung, 2008; Okada, Yanagisawa, & Taira, 1993; Urena, del Valle-Rodriguez, & Lopez-Barneo, 2007; Yamagishi, Yanagisawa, & Taira, 1992; Yamamura, Ohya, Muraki, & Imaizumi, 2012; Yanagisawa, Yamagishi, & Okada, 1993). Potassium channels also contribute to the regulation of proliferation of VSM cells through membrane potential-dependent (Bi et al, 2013; Miguel-Velado et al, 2005; Miguel-Velado et al, 2010) and membrane potential-independent mechanisms (Cidad et al, 2012; Cidad et al, 2015; Jimenez-Perez et al, 2016). …”