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.

Extracellular modulation of TREK-2 activity with nanobodies provides insight into the mechanisms of K2P channel regulation

“…Previous studies have demonstrated the usefulness of nanobodies for immunodetection as well as in various immunoassays and other nanobody-based protein targeting strategies (19, 28). The structures determined above show that these TREK-2 nanobodies bind to the extracellular Cap domain indicating that immunodetection of TREK-2 at the cell surface should be possible.…”

“…For some classes of ion channels, the adaptation of channel toxins and the development of RNA-based antagonists has been successful in achieving greater target selectivity (17,18), but perhaps the most promising approaches involve biologics that exploit protein-protein interactions for target recognition (19)(20)(21)(22). Many antibody-based therapies are now in clinical use for the treatment of a variety of disorders and have a number of potential benefits compared to traditional approaches although their identification and development can be costly (23).…”

Long-Term Blockade of Nociceptive Nav1.7 Channels Is Analgesic in Rat Models of Knee Arthritis

“…Antibodies that are directed towards extracellular domains are fraught with reduced specificity and accessible binding sites are limited. Since the majority of the Na v channel occurs in the cytoplasm and the associated subunits are highly conserved, antibodies that target intracellular components offer a more desirable means of selectively modulating the ion channel [ 8 ]. The principal challenge with this approach is that antibodies are not able to pass through cellular membranes to reach intracellular components.…”

“…Carbamazapine, for example, binds to the α-subunit of the channel and keeps it in the closed, inactivated state such that sodium ions cannot flow across the neurolemma and cause depolarisation [ 5 , 6 , 7 ]. Other agents such as tetrodotoxin block the channel pore while antibodies directed towards intracellular subunits can alter channel gating properties [ 8 , 9 ]. The arylsulfonamide inhibitor of Na v 1.7 PF05089771 binds to the extracellular voltage-sensing domain VSD4 of the channel where it blocks action potential generation and reduces afferent firing [ 10 ].…”

“…An alternative approach is to use a biologic directed against Na v 1.7 which has the potential to extend the therapeutic window and improve target selectivity. Antibodies directed towards an external domain have been shown to be effective at modulating ion channel function; however, only a small fraction of the channel protein is available for antibody docking and recognition sites are often shared with other ion channel subtypes [ 8 ]. Intracellular domains are more abundant and channel-specific, but the ability for a large molecule such as an antibody to cross the plasma membrane to reach these elements remains a challenge.…”