Modulation Of Potassium Channels Research Articles

Molecular mapping of KCNE4-dependent regulation of Kv1.3.

The voltage-gated potassium channel Kv1.3 plays a crucial role in the immune system response. In leukocytes, the channel is coexpressed with the dominant negative regulatory subunit KCNE4, which associates with Kv1.3 to trigger intracellular retention and accelerating C-type inactivation of the channel. Previous research has demonstrated that the main association between these proteins occurs through both C-termini. However, these data fail to fully elucidate the KCNE4-dependent modulation of channel kinetics. In the present study, we analyzed the contribution of each KCNE4 domain to the modulation of Kv1.3. Our results further confirmed that the C-terminus of KCNE4 is the main determinant involved in the association-triggered intracellular retention of the channel. Moreover, interactions throughout the transmembrane region were also observed. Both the C-terminus and, especially, the transmembrane domain of KCNE4 accentuated the C-type inactivation of Kv1.3. Our data provide, for the first time, the molecular effects that a KCNE peptide, such as KCNE4, exerts on a Shaker channel, such as Kv1.3. Our results pave the way for understanding the molecular mechanisms underlying potassium channel modulation and suggest that KCNE4 participates in the conformational rearrangement of the Kv1.3 architecture, altering the C-type inactivation of the channel.

Hydroquinidine Demonstrates Remarkable Antineoplastic Effects on Non-small Cell Lung Cancer Cells.

Despite recent progress in drug development, lung cancer remains a complex disease that poses a major public health issue worldwide, and new therapeutic strategies are urgently needed because of the failure of standard treatments. Ion channels play a critical role in various cellular processes that regulate cell proliferation, differentiation, and cell death. The potential of ion channel modulators as tumor growth suppressors has been highlighted in recent studies. Therefore, we hypothesized that hydroquinidine (HQ), a previously understudied potassium channel modulator, might have anticarcinogenic activity against A549 cells. The anticancer potential of HQ was investigated using various wellestablished in vitro assays. HQ significantly decreased colony formation and tumorigenicity and exhibited a significant anti-migratory effect in A549 cells. Our results demonstrated that HQ significantly inhibited the growth of cancer cells by decreasing the proliferation rate while increasing cell death. The altered gene expression profile in response to treatment with HQ was consistent with the observed cellular effects. Incubation of cells with HQ resulted in the downregulation of genes involved in cell division and survival, while genes promoting cell cycle arrest and apoptosis were upregulated. Our findings suggest that HQ has the potential to limit lung cancer growth as a novel potent anticarcinogenic agent. However, more investigations are needed to gain further insight into the mechanism of action of HQ and to evaluate its efficacy in invivo models.

The Multifunctional Role of KCNE2: From Cardiac Arrhythmia to Multisystem Disorders.

The KCNE2 protein is encoded by the kcne2 gene and is a member of the KCNE protein family, also known as the MinK-related protein 1 (MiRP1). It is mostly present in the epicardium of the heart and gastric mucosa, and it is also found in the thyroid, pancreatic islets, liver and lung, among other locations, to a lesser extent. It is involved in numerous physiological processes because of its ubiquitous expression and partnering promiscuity, including the modulation of voltage-dependent potassium and calcium channels involved in cardiac action potential repolarization, and regulation of secretory processes in multiple epithelia, such as gastric acid secretion, thyroid hormone synthesis, generation and secretion of cerebrospinal fluid. Mutations in the KCNE2 gene or aberrant expression of the protein may play a critical role in cardiovascular, neurological, metabolic and multisystem disorders. This article provides an overview of the advancements made in understanding the physiological functions in organismal homeostasis and the pathophysiological consequences of KCNE2 in multisystem diseases.

Characterization and modulation of voltage-gated potassium channels in human lymphocytes in schizophrenia

BackgroundIt is known that the immune system is dysregulated in schizophrenia, having a state similar to chronic neuroinflammation. The origin of this process is unknown, but it is known that T and B lymphocytes, which are components of the adaptive immune system, play an important role in the pathogenic mechanisms of schizophrenia. MethodsWe analysed the membrane of PBMCs from patients diagnosed with schizophrenia through proteomic analysis (n = 5 schizophrenia and n = 5 control). We found the presence of the Kv1.3 voltage-gated potassium channel and its auxiliary subunit β1 (KCNAB1) and β2 (KCNAB2). From a sample of 90 participants, we carried out a study on lymphocytes with whole-cell patch-clamp experiments (n = 7 schizophrenia and n = 5 control), western blot (n = 40 schizophrenia and n = 40 control) and confocal microscopy to evaluate the presence and function of different channels. Kv in both cells. ResultsWe demonstrated the overexpression of Kv1.1, Kv1.2, Kv1.3, Kv1.6, Kv4.2, Kv4.3 and Kv7.2 channels in PBMCs from patients with schizophrenia. This study represents a groundbreaking exploration, as it involves an electrophysiological analysis performed on T and B lymphocytes from patients diagnosed of schizophrenia compared to healthy participants. We observed that B lymphocytes exhibited an increase in output current along with greater peak current amplitude and voltage conductance curves among patients with schizophrenia compared with healthy controls. ConclusionsThis study showed the importance of the B lymphocyte in schizophrenia. We know that the immune system is altered in schizophrenia, but the physiological mechanisms of this system are not very well known. We suggest that the B lymphocyte may be relevant in the pathophysiology of schizophrenia and that it should be investigated in more depth, opening a new field of knowledge and possibilities for new treatments combining antipsychotics and immunomodulators. The limitation is that all participants received antipsychotic medication, which may have influenced the differences observed between patients and controls. This implies that more studies need to be done where the groups can be separated according to the antipsychotic drug.

The A-kinase anchoring protein Yotiao decrease the ER calcium content by inhibiting the store operated calcium entry

The meticulous regulation of ER calcium (Ca2+) homeostasis is indispensable for the proper functioning of numerous cellular processes. Disrupted ER Ca2+ balance is implicated in diverse diseases, underscoring the need for a systematic exploration of its regulatory factors in cells. Our recent genomic-scale screen identified a scaffolding protein A-kinase anchoring protein 9 (AKAP9) as a regulator of ER Ca2+ levels, but the underlying molecular mechanisms remain elusive. Here, we reveal that Yotiao, the smallest splicing variant of AKAP9 decreased ER Ca2+ content in animal cells. Additional testing using a combination of Yotiao truncations, knock-out cells and pharmacological tools revealed that, Yotiao does not require most of its interactors, including type 1 inositol 1,4,5-trisphosphate receptors (IP3R1), protein kinase A (PKA), protein phosphatase 1 (PP1), adenylyl cyclase type 2 (AC2) and so on, to reduce ER Ca2+ levels. However, adenylyl cyclase type 9 (AC9), which is known to increases its cAMP generation upon interaction with Yotiao for the modulation of potassium channels, plays an essential role for Yotiao's ER-Ca2+-lowering effect. Mechanistically, Yotiao may work through AC9 to act on Orai1-C terminus and suppress store operated Ca2+ entry, resulting in reduced ER Ca2+ levels. These findings not only enhance our comprehension of the interplay between Yotiao and AC9 but also contribute to a more intricate understanding of the finely tuned mechanisms governing ER Ca2+ homeostasis.

Electro-Metabolic Coupling of Cumulus-Oocyte Complex.

Oocyte-cumulus cell interaction is essential for oocyte maturation and competence. The bidirectional crosstalk network mediated by gap junctions is fundamental for the metabolic cooperation between these cells. As cumulus cells exhibit a more glycolytic phenotype, they can provide metabolic substrates that the oocyte can use to produce ATP via oxidative phosphorylation. The impairment of mitochondrial activity plays a crucial role in ovarian aging and, thus, in fertility, determining the success or failure of assisted reproductive techniques. This review aims to deepen the knowledge about the electro-metabolic coupling of the cumulus-oocyte complex and to hypothesize a putative role of potassium channel modulators in order to improve fertility, promote intracellular Ca2+ influx, and increase the mitochondrial biogenesis and resulting ATP levels in cumulus cells.

The impact of ATP-sensitive potassium channel modulation on mitochondria in a Parkinson’s disease model using SH-SY5Y cells depends on their differentiation state

Inward rectifying potassium channels sensitive to ATP levels (KATP) have been the subject of investigation for several decades. Modulators of KATP channels are well-established treatments for metabolic as well as cardiovascular diseases. Experimental studies have also shown the potential of KATP modulation in neurodegenerative disorders. However, to date, data regarding the effects of KATP antagonists/agonists in experiments related to neurodegeneration remain inconsistent. The main source of confusion in evaluating available data seems to be the choice of experimental models. The present study aims to provide a comprehensive understanding of the effects of both opening and blocking KATP channels in two forms of SH-SY5Y cells. Our results offer valuable insights into the significance of metabolic differences between differentiated and non-differentiated SH-SY5Y cells, particularly in the context of glibenclamide and diazoxide effects under normal conditions and during the initiation of pathological events simulating Parkinson’s disease in vitro. We emphasize the analysis of mitochondrial functions and changes in mitochondrial network morphology. The heightened protein expression of KATP channels identified in non-differentiated SH-SY5Y cells seems to be a platform for a more significant impact of KATP modulators in this cell type. The efficiency of rotenone treatment in inducing morphological changes in the mitochondrial network depends on the differentiation status of SH-SY5Y cells.

Redox Regulation of Mitochondrial Potassium Channels Activity.

Redox reactions exert a profound influence on numerous cellular functions with mitochondria playing a central role in orchestrating these processes. This pivotal involvement arises from three primary factors: (1) the synthesis of reactive oxygen species (ROS) by mitochondria, (2) the presence of a substantial array of redox enzymes such as respiratory chain, and (3) the responsiveness of mitochondria to the cellular redox state. Within the inner mitochondrial membrane, a group of potassium channels, including ATP-regulated, large conductance calcium-activated, and voltage-regulated channels, is present. These channels play a crucial role in conditions such as cytoprotection, ischemia/reperfusion injury, and inflammation. Notably, the activity of mitochondrial potassium channels is intricately governed by redox reactions. Furthermore, the regulatory influence extends to other proteins, such as kinases, which undergo redox modifications. This review aims to offer a comprehensive exploration of the modulation of mitochondrial potassium channels through diverse redox reactions with a specific focus on the involvement of ROS.

Modulation of potassium channels by transmembrane auxiliary subunits via voltage-sensing domains.

Voltage-gated K+ (KV ) and Ca2+ -activated K+ (KCa ) channels are essential proteins for membrane repolarization in excitable cells. They also play important physiological roles in non-excitable cells. Their diverse physiological functions are in part the result of their auxiliary subunits. Auxiliary subunits can alter the expression level, voltage dependence, activation/deactivation kinetics, and inactivation properties of the bound channel. KV and KCa channels are activated by membrane depolarization through the voltage-sensing domain (VSD), so modulation of KV and KCa channels through the VSD is reasonable. Recent cryo-EM structures of the KV or KCa channel complex with auxiliary subunits are shedding light on how these subunits bind to and modulate the VSD. In this review, we will discuss four examples of auxiliary subunits that bind directly to the VSD of KV or KCa channels: KCNQ1-KCNE3, Kv4-DPP6, Slo1-β4, and Slo1-γ1. Interestingly, their binding sites are all different. We also present some examples of how functionally critical binding sites can be determined by introducing mutations. These structure-guided approaches would be effective in understanding how VSD-bound auxiliary subunits modulate ion channels.

Dual Extracellular Recordings in the Mouse Hippocampus and Prefrontal Cortex.

The technique of recording local field potentials (LFPs) is an electrophysiological method used to measure the electrical activity of localized neuronal populations. It serves as a crucial tool in cognitive research, particularly in brain regions like the hippocampus and prefrontal cortex. Dual LFP recordings between these areas are of particular interest as they allow the exploration of interregional signal communication. However, methods for performing these recordings are rarely described, and most commercial recording devices are either expensive or lack adaptability to accommodate specific experimental designs. This study presents a comprehensive protocol for performing dual-electrode LFP recordings in the mouse hippocampus and the prefrontal cortex to investigate the effects of antipsychotic drugs and potassium channel modulators on LFP properties in these areas. The technique enables the measurement of LFP properties, including power spectra within each brain region and coherence between the two. Additionally, a low-cost, custom-designed recording device has been developed for these experiments. In summary, this protocol provides a means to record signals with high signal-to-noise ratios in different brain regions, facilitating the investigation of interregional information communication within the brain.

Potassium channel modulation in macrophages sensitizes dorsal root ganglion neurons after nerve injury.

Macrophages and satellite glial cells are found between injured and uninjured neurons in the lumbar dorsal root ganglia (DRG). We explored the mechanism of neuro-immune and neuron-glia crosstalk leading to hyperexcitability of DRG neurons. After spared nerve injury (SNI), CX3CR1+ resident macrophages became activated, proliferated, and increased inward-rectifying potassium channel Kir 2.1 currents. Conditioned medium (CM) by macrophages, obtained from DRG of SNI mice, sensitized small DRG neurons from naïve mice. However, treatment with CM from GFAP+ glial cells did not affect neuronal excitability. When subjected to this macrophage-derived CM, DRG neurons had increased spontaneous activity, current-evoked responses and voltage-gated NaV 1.7 and NaV 1.8 currents. Silencing Kir 2.1 in macrophages after SNI prevented the induction of neuronal hyperexcitability from their CM. Blocking vesicular exocytosis or soluble tumor necrosis factor in CM or interfering with the downstream intracellular p38 pathway in neurons, also prevented neuronal hyperexcitability. Blocking protein trafficking in neurons reduced the effect of CM, suggesting that the hyperexcitable state resulted from changes in NaV channel trafficking. These results suggest that DRG macrophages, primed by peripheral nerve injury, contribute to neuron-glia crosstalk, NaV channel dysregulation and neuronal hyperexcitability implicated in the development of neuropathic pain.

Modulation of Mechanosensitive Potassium Channels by a Membrane-targeted Nongenetic Photoswitch.

Mechanosensitive ion channels are present in the plasma membranes of all cells. They play a fundamental role in converting mechanical stimuli into biochemical signals and are involved in several physiological processes such as touch sensation, hearing, and blood pressure regulation. This protein family includes TWIK-related arachidonic acid-stimulated K+ channel (TRAAK), which is specifically implicated in the maintenance of the resting membrane potential and in the regulation of a variety of important neurobiological functions. Dysregulation of these channels has been linked to various diseases, including blindness, epilepsy, cardiac arrhythmia, and chronic pain. For these reasons, mechanosensitive channels are targets for the treatment of several diseases. Here, we propose a new approach to investigate TRAAK ion channel modulation that is based on nongenetic photostimulation. We employed an amphiphilic azobenzene, named Ziapin2. In the dark, Ziapin2 preferentially dwells in the plasma membrane, causing a thinning of the membrane. Upon light irradiation, an isomerization occurs, breaking the dimers and inducing membrane relaxation. To study the effect of Ziapin2 on the mechanosensitive channels, we expressed human TRAAK (hTRAAK) channels in HEK293T cells. We observed that Ziapin2 insertion in the membrane is able per se to recruit hTRAAK, permitting the exit of K+ ions outside the cells with a consequent hyperpolarization of the cell membrane. During light stimulation, membrane relaxation induces hTRAAK closure, generating a consistent and compensatory depolarization. These results add information to the Ziapin2 mechanism and suggest that membrane deformation can be a tool for the nonselective modulation of mechanosensitive channels.

Hypoxia Promotes Atrial Tachyarrhythmias via Opening of ATP-Sensitive Potassium Channels.

Hypoxia-ischemia predisposes to atrial arrhythmia. Atrial ATP-sensitive potassium channel (KATP) modulation during hypoxia has not been explored. We investigated the effects of hypoxia on atrial electrophysiology in mice with global deletion of KATP pore-forming subunits. Whole heart KATP RNA expression was probed. Whole-cell KATP current and action potentials were recorded in isolated wild-type (WT), Kir6.1 global knockout (6.1-gKO), and Kir6.2 global knockout murine atrial myocytes. Langendorff-perfused hearts were assessed for atrial effective refractory period (ERP), conduction velocity, wavefront path length (WFPL), and arrhymogenicity under normoxia/hypoxia using a microelectrode array and programmed electrical stimulation. Heart histology was assessed. Expression patterns were essentially identical for all KATP subunit RNA across human heart, whereas in mouse, Kir6.1 and SUR2 (sulphonylurea receptor) were higher in ventricle than atrium, and Kir6.2 and SUR1 were higher in atrium. Compared with WT, Kir6.2 global knockout atrial myocytes had reduced tolbutamide-sensitive current and action potentials were more depolarized with slower upstroke and reduced peak amplitude. Action potential duration was prolonged in 6.1-gKO atrial myocytes, absent of changes in other ion channel gene expression or atrial myocyte hypertrophy. In Langendorff-perfused hearts, baseline atrial ERP was prolonged and conduction velocity reduced in both KATP knockout mice compared with WT, without histological fibrosis. Compared with baseline, hypoxia led to conduction velocity slowing, stable ERP, and WFPL shortening in WT and 6.1-gKO hearts, whereas WFPL was stable in Kir6.2 global knockout hearts due to ERP prolongation with conduction velocity slowing. Tolbutamide reversed hypoxia-induced WFPL shortening in WT and 6.1-gKO hearts through ERP prolongation. Atrial tachyarrhythmias inducible with programmed electrical stimulation during hypoxia in WT and 6.1-gKO mice correlated with WFPL shortening. Spontaneous arrhythmia was not seen. KATP block/absence leads to cellular and tissue level atrial electrophysiological modification. Kir6.2 global knockout prevents hypoxia-induced atrial WFPL shortening and atrial arrhythmogenicity to programmed electrical stimulation. This mechanism could be explored translationally to treat ischemically driven atrial arrhythmia.

Pharmacological modulation of Kv3 voltage-gated potassium channels regulates fear discrimination and expression in a response-dependent manner

Various psychiatric diseases are characterized by aberrant cognition and emotional regulation. This includes inappropriately attributing affective salience to innocuous cues, which can be investigated using translationally relevant preclinical models of fear discrimination. Activity in the underpinning corticolimbic circuitry is governed by parvalbumin-expressing GABAergic interneurons, which also regulate fear discrimination. Kv3 voltage-gated potassium channels are highly expressed in these neurons and are important for controlling their activity, suggesting that pharmacological Kv3 modulation may regulate fear discrimination. We determined the effect of the positive Kv3 modulator AUT00206 given systemically to female rats undergoing limited or extended auditory fear discrimination training, which we have previously shown results in more discrimination or generalization, respectively, based on freezing at retrieval. We also characterized darting and other active fear-related responses. We found that limited training resulted in more discrimination based on freezing, which was unaffected by AUT00206. In contrast, extended training resulted in more generalization based on freezing and the emergence of discrimination based on darting during training and, to a lesser extent, at retrieval. Importantly, AUT00206 given before extended training had dissociable effects on fear discrimination and expression at retrieval depending on the response examined. While AUT00206 mitigated generalization without affecting expression based on freezing, it reduced expression without affecting discrimination based on darting, although darting levels were low overall. These results indicate that pharmacological Kv3 modulation regulates fear discrimination and expression in a response-dependent manner. They also raise the possibility that targeting Kv3 channels may ameliorate perturbed cognition and emotional regulation in psychiatric disease.

Single Neuron Modeling Identifies Potassium Channel Modulation as Potential Target for Repetitive Head Impacts.

Traumatic brain injury (TBI) and repetitive head impacts can result in a wide range of neurological symptoms. Despite being the most common neurological disorder in the world, repeat head impacts and TBI do not have any FDA-approved treatments. Single neuron modeling allows researchers to extrapolate cellular changes in individual neurons based on experimental data. We recently characterized a model of high frequency head impact (HFHI) with a phenotype of cognitive deficits associated with decreases in neuronal excitability of CA1 neurons and synaptic changes. While the synaptic changes have been interrogated in vivo, the cause and potential therapeutic targets of hypoexcitability following repetitive head impacts are unknown. Here, we generated in silico models of CA1 pyramidal neurons from current clamp data of control mice and mice that sustained HFHI. We use a directed evolution algorithm with a crowding penalty to generate a large and unbiased population of plausible models for each group that approximated the experimental features. The HFHI neuron model population showed decreased voltage gated sodium conductance and a general increase in potassium channel conductance. We used partial least squares regression analysis to identify combinations of channels that may account for CA1 hypoexcitability after HFHI. The hypoexcitability phenotype in models was linked to A- and M-type potassium channels in combination, but not by any single channel correlations. We provide an open access set of CA1 pyramidal neuron models for both control and HFHI conditions that can be used to predict the effects of pharmacological interventions in TBI models.

XEN1101, a Novel Potassium Channel Modulator: Interim Data From an Ongoing, Long-Term, Open-Label Extension of a Phase 2b study (X-TOLE) in Adults with Focal Epilepsy (S44.008)

XEN1101, a Novel Potassium Channel Modulator: Interim Data From an Ongoing, Long-Term, Open-Label Extension of a Phase 2b study (X-TOLE) in Adults with Focal Epilepsy (S44.008)

Validation of TREK1 ion channel activators as an immunomodulatory and neuroprotective strategy in neuroinflammation.

Modulation of two-pore domain potassium (K2P) channels has emerged as a novel field of therapeutic strategies as they may regulate immune cell activation and metabolism, inflammatory signals, or barrier integrity. One of these ion channels is the TWIK-related potassium channel 1 (TREK1). In the current study, we report the identification and validation of new TREK1 activators. Firstly, we used a modified potassium ion channel assay to perform high-throughput-screening of new TREK1 activators. Dose-response studies helped to identify compounds with a high separation between effectiveness and toxicity. Inside-out patch-clamp measurements of Xenopus laevis oocytes expressing TREK1 were used for further validation of theseactivators regarding specificity and activity. These approaches yielded three substances, E1, B3 and A2 that robustly activate TREK1. Functionally, we demonstrated that these compounds reduce levels of adhesion molecules on primary human brain and muscle endothelial cells without affecting cell viability. Finally, we studied compound A2 via voltage-clamp recordings as this activator displayed the strongest effect on adhesion molecules. Interestingly, A2 lacked TREK1 activation in the tested neuronal cell type. Taken together, this study provides data on novel TREK1 activators that might be employed to pharmacologically modulate TREK1 activity.

Identification of Biologically Diverse Tetrahydronaphthalen-2-ols through the Synthesis and Phenotypic Profiling of Chemically Diverse, Estradiol-Inspired Compounds.

Combining natural product fragments to design new scaffolds with unprecedented bioactivity is a powerful strategy for the discovery of tool compounds and potential therapeutics. However, the choice of fragments to couple and the biological screens to employ remain open questions in the field. By choosing a primary fragment containing the A/B ring system of estradiol and fusing it to nine different secondary fragments, we were able to identify compounds that modulated four different phenotypes: inhibition of autophagy and osteoblast differentiation, as well as potassium channel and tubulin modulation. The latter two were uncovered by using unbiased morphological profiling with a cell-painting assay. The number of hits and variety in bioactivity discovered validates the use of recombining natural product fragments coupled to phenotypic screening for the rapid identification of biologically diverse compounds.

Modulation of heteromeric Kv1 channels by transmembrane lectins and redox.

Voltage-gated potassium channels regulate cellular electrical activity and are influenced by a variety of stimuli including redox and accessory proteins. Kv1.2 channels are exquisitely sensitive to reducing agents, which promote an ‘inhibited’ gating mode characterized by a large depolarizing shift of voltage-dependence, decelerated activation kinetics, and use-dependent activation. Similarly, overexpression of Kv1.2 channels with transmembrane lectin LMAN2 recapitulates these functional outcomes. Kv1 family subunits assemble as heterotetramers with potential tremendous diversity of function and sensitivity. It is unclear whether or how redox or LMAN2 sensitivity of Kv1.2 influences other insensitive Kv1 subtypes when assembled in heteromeric channels. In this study, we tested the redox and LMAN2 sensitivity of a series of homomeric Kv1 and tandem-linked Kv1.2-1.X heteromeric channels. We report that among homomeric channels, redox and LMAN2 sensitivity is exclusive to Kv1.2, while in Kv1.2-containing heteromeric channels, this sensitivity persists. Redox and LMAN2 decelerated the activation kinetics of Kv1.2-containing channels but had no effect on the deactivation kinetics. Interestingly, some Kv1 subtypes (notably Kv1.1 and Kv1.4) appear to be more sensitive than others to Kv1.2-mediated modulation. In summary, these data indicate that Kv1.2 acts as an adaptor subunit capable of recruiting sensitivity to redox and certain accessory proteins. These findings broaden our understanding of the mechanism of modulation of heteromeric voltage-gated potassium channels.

Regulation of Kir2.1 channels by ubiquitin-like modifier proteins.

The strong inward-rectifying subclass of potassium channel Kir2.1 produces IK1 current in the human myocardium which stabilizes the resting membrane potential of the heart and shapes the cardiac action potential. Perturbation or disruption of IK1 is associated with various arrhythmic phenotypes. Multiple studies have provided extensive evidence for the modulation of potassium channels by endogenous regulatory proteins. This group has studied extensively the relationship between the small ubiquitin-like modifier SUMO and Kir2.1 biophysical properties. Using patch clamp and Förster resonance energy transfer (FRET) studies in heterologous cells and rat ventricular cardiomyocytes (RVCM), we have demonstrated that SUMO interacts with Kir2.1 at a key lysine residue K49; the proximate physical association of which SUMO associates with the channel interferes with the binding pocket for phosphatidylinositol bisphosphate 2 (PIP2) required for channel gating, resulting in decreased IK1 current. Recent studies have posited an important role for another ubiquitin-like modifier, FAT10 in the regulation of ion channels that are expressed in the myocardium. While our group has characterized that acute hypoxia inhibits IK1 current in RVCM by an increased SUMOylation mechanism, another group has shown that FAT10 expression is markedly increased in hypoxia RVCMs. Together with studies showing evidence of competition for common target proteins between SUMO and FAT10, we seek to elucidate a mechanism of FAT10ylation of Kir2.1. Using FRET, we show disrupted SUMOylation in the presence of FAT10 in the heterologous cell system. Using electrophysiological techniques, we also demonstrate a change in Kir2.1 channel dynamics when FAT10 is co-expressed in both Xenopus laevis oocytes and HEK293T cells. Lastly, this work establishes a foundation for the study of Kir2.1 channel FAT10ylation in the native cardiomyocyte system in which FAT10 is posited to have a cardioprotective effect.