Controlling ion channel function with renewable recombinant antibodies

Abstract

Selective ion channel modulators play a critical role in physiology in defining the contribution of specific ion channels to physiological function and as proof of concept for novel therapeutic strategies. Antibodies are valuable research tools that have broad uses including defining the expression and localization of ion channels in native tissue, and capturing ion channel proteins for subsequent analyses. In this review, we detail how renewable and recombinant antibodies can be used to control ion channel function. We describe the different forms of renewable and recombinant antibodies that have been used and the mechanisms by which they modulate ion channel function. We highlight the use of recombinant antibodies that are expressed intracellularly (intrabodies) as genetically encoded tools to control ion channel function. We also offer perspectives of avenues of future research that may be opened by the application of emerging technologies for engineering recombinant antibodies for enhanced utility in ion channel research. Overall, this review provides insights that may help stimulate and guide interested researchers to develop and incorporate renewable and recombinant antibodies as valuable tools to control ion channel function.

Keywords: antibody; intrabody; ion channel modulation; nanobody; scFv.

Figure 1.

Forms of antibodies used to control ion channels. Panel A. Left. A typical mammalian IgG antibody. Light chains comprise one variable (V_L, pink) and one constant (C_L, light grey) domain. Heavy chains comprise one variable domain (V_H, red) and three constant (C_H1–3, dark grey) domains. The antigen binding surface is formed by the assembled V_L and V_H domains. Typical mammalian H + L chain IgGs can be miniaturized to various forms. These include single chain variable fragments or ScFvs (middle), which can be tethered to V_H domains to yield scFv-Fc fusions. Panel B. Camelid HC-only IgGs exist as a homodimer of two identical H chains. The antigen-binding surface is contained within a single V_HH domain, which can function autonomously as a nanobody (nAb).

Figure 2.

Extracellular antibody-mediated control of ion channels. Schematic depicts from left to right the anti-Kv10.1 mAb56 (dark blue) mediating inhibition of the Kv10.1 K⁺ channel (tan), the scFv62-TRAIL fusion (the anti-Kv10.1 scFv62 is in light purple, TRAIL is in pink) mediating apoptosis of Kv10.1-expressing cancer cells, the K57/1-porphyrin conjugate (the anti-Kv4.2 mAb K57/1 is in purple, porphyrin is in red) mediating reactive oxygen species (ROS)-induced photoablation of the activity of the Kv4.2 K⁺ channel (light blue), and the anti-Fluc L3 monobody (grey) mediating inhibition of the Fluc F⁻ channel (green).

Figure 3.

Intracellular antibody-mediated control of ion channels. Schematic depicts from left to right the anti-Kv2.1 mAb K89/34 (dark green) mediating inhibition of the Kv2.1 K⁺ channel (light green), the anti-KChIP3 mAb K66/38 (purple) mediating inhibition of the Cav2/Cav3 Ca²⁺ channel (light orange) mediated Ca²⁺-dependent modulation of Kv4.2/KChIP3 K⁺ channels (Kv4.2 in light purple, KChIP3 in dark blue).

Figure 4.

Genetically-encoded intrabody-mediated control of ion channels. Schematic depicts from left to right the anti-hERG scFvs 2.10 and 2.12 (tan) mediating inhibition of the hERG K+ channel (light green), the T2a-USP21 fusion (the anti-CFTR nanobody T2a is in tan, the USP21 deubiquitinase catalytic domain is in dark blue) catalyzing the deubiquitination of DF508 mutant CFTR channels (purple) leading to their enhanced surface expression, and the nb.F3 nAb-Nedd4L fusion (the anti-Cavβ nanobody nb.F3 is in green, the catalytic HECT domain of the Nedd4L E3 ubiquitin ligase Nedd4L is in red) catalyzing the ubiquitination of the Cav1.2/Cavβ Ca2+ channel leading to their inhibition (the Cav1.2 α1 subunit is in light blue, and the Cavβ subunit is in dark blue).