Biology subjects

Light, P. E.

Publications and source records attributed to Light, P. E..

3 recordsLinked to original sources

bioRxiv2026

Computational modelling of natural cell-to-cell heterogeneity reveals key parameters that control the diversity of human pancreatic islet β-cell excitability in response to glucose

Insulin-producing {beta}-cells demonstrate remarkable heterogeneity in their individual responsiveness to glucose, and that cellular heterogeneity contributes to coordinating islet activity and glucose homeostasis. Our current understanding of how variation in cell-intrinsic factors control cellular excitability and insulin secretion is informed by foundational experiments conducted on dispersed single {beta}-cells. Such studies are limited in their ability to link multiple electrical or metabolic properties within a single cell and preclude the ability to relate, post hoc, each parameters contribution to glucose responsiveness. Computational modelling represents a unique and underutilized tool to integrate and investigate the role of natural {beta}-cell heterogeneity in physiologic glucose responses. Herein, we utilize a high-volume single-cell electrophysiology "patch-seq" dataset to define the physiologically relevant sources of variability in human {beta}-cell electrophysiology and model their influence on single-cell glucose responses. Three thousand in silico human {beta}-cells were fitted to physiologically relevant variations in glucokinase activity, K+ current, Na+ current, Ca2+ current, and exocytotic function. Four dominant electrical phenotypes arose at low (2 mM) and high (20 mM) glucose: silent, bursting, spiking, and depolarized. Approximately 50% of uncoupled {beta}-cells remained electrically silent at high glucose. Furthermore, Na+ channel half-inactivation voltage was a major predictor of the silent and spiking phenotypes at each glucose concentration, and of cells that transition from silent to spiking when glucose increased. Indeed, experimentally observed variation in Na+ channel voltage dependence was second only to variation in ATP-sensitive potassium channel conductance in determining {beta}-cell excitability. Our data-driven computational modelling highlights the functional importance of electrical heterogeneity in human {beta}-cell glucose responses, and provides a useful tool for generating testable hypotheses.

physiology↗

bioRxiv2024

The Sodium/Glucose Cotransporter 2 Inhibitor Empagliflozin Inhibits Long QT 3 Late Sodium Currents in a Mutation Specific Manner

BackgroundSodium/glucose cotransporter 2 inhibitors (SGLT2is) such as empagliflozin have demonstrated substantial cardioprotective effects in patients with or without diabetes. The SGLT2is have been shown to selectively inhibit the late component of cardiac sodium current (late INa). Induction of late INa is also the primary mechanism involved in the pathophysiology of congenital long QT syndrome type 3 (LQT3) gain-of-function mutations in the SCN5A gene that encodes the major cardiac sodium channel isoform Nav1.5. Therefore, we investigated the effect of empagliflozin on late INa in thirteen known LQT3 mutations located in distinct regions of the channel structure. MethodsThe whole-cell patch-clamp technique was used to investigate the effect of empagliflozin (10 {micro}M) on late INa in recombinantly expressed Nav1.5 channels containing different LQT3 mutations. Molecular modeling of human Nav1.5 and simulations in a mathematical model of human ventricular myocytes were used to extrapolate our experimental results to excitation contraction coupling. ResultsEmpagliflozin selectively inhibited late INa in LQT3 mutations residing in the inactivation gate region of Nav1.5, with no effect on either peak current or channel kinetics. In contrast, empagliflozin caused inhibition of both peak and late INa in mutations in the S4 voltage-sensing regions as well as changes in activation and inactivation kinetics and a slowing of recovery from inactivation. Empagliflozin had no effect on late/peak INa or channel kinetics in channels containing LQT3 mutations located in the putative empagliflozin binding region. Simulation of our experimental findings in a mathematical model of human ventricular myocytes predicts that empagliflozin may have a desirable therapeutic effect in LQT3 mutations located in the inactivation gate region. ConclusionsOur results show that empagliflozin selectively inhibits late INa, without affecting gating kinetics, in LQT3 mutations residing in the inactivation gate region. Patients with mutations in voltage-sensing regions are less suitable candidates as empagliflozin may prevent action potential firing. The SGLT2is may therefore be a promising novel precision medicine approach for patients with certain LQT3 mutations.

pharmacology and toxicology↗

bioRxiv2021

TACAN is a novel regulator of PKD2

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in membrane receptor PKD1 or cation channel PKD2. TACAN (also named TMEM120A), recently reported as an ion channel in neuron cells for mechano and pain sensing, is also distributed in diverse non-neuronal tissues such as kidney, heart and intestine, suggesting its involvement in other functions. In this study, we found that TACAN is in complex with PKD2 in native renal cell lines. Using the two-electrode voltage clamp in Xenopus oocytes we found that TACAN inhibited the channel activity of PKD2 gain-of-function mutant F604P. The first and last transmembrane domains of TACAN were found to interact with the PKD2 C-and N-terminal portions, respectively. We showed that the TACAN N-terminus acted as a blocking peptide and that TACAN inhibits the PKD2 function through the PKD2/TACAN binding. By patch clamping in mammalian cells, we found that TACAN inhibits both the single channel conductance and open probability of PKD2 and mutant F604P. PKD2 co-expressed with TACAN, but not PKD2 alone, exhibited pressure sensitivity. Furthermore, we also found that TACAN aggravates PKD2-dependent tail curvature and pronephric cysts in larval zebrafish, in support of the in vitro inhibitory effects of TACAN. In summary, this study revealed that TACAN acts as a PKD2 inhibitor and mediates mechano sensitivity of the PKD2/TACAN channel complex.

physiology↗