Biology subjects

Kickinger, S.

Publications and source records attributed to Kickinger, S..

4 recordsLinked to original sources

bioRxiv2025

Coupling between acid-sensing ion channel 1a and the monocarboxylate transporter family shapes cellular pH response

Proton-mediated activation of acid-sensing ion channel 1a (ASIC1a) leads to influx of sodium and, to a lesser extent, calcium, followed by rapid and complete desensitization. However, various ASIC1a-expressing cell types display atypical proton-induced currents characterized by altered proton sensitivity and slow and incomplete desensitization. The origin of this functional diversity and its physiological relevance remain unclear. Here, we show that the monocarboxylate transporter 1 (MCT1) interacts with ASIC1a, leading to subtype-specific modulation of proton sensitivity and desensitization. We delineate the molecular mechanism of the ASIC1a-MCT1 coupling and find that the presence of MCT1 is required for the distinct ASIC1a-mediated currents observed in glioblastoma cells, the most lethal brain cancer in adults. Strikingly, presence of ASIC1a together with MCT1 significantly prolongs the lifespan of mice intracranially injected with glioblastoma cells. We thus uncover the basis for altered ASIC1a function in glioblastoma and highlight the importance of deciphering the cell-type specific ASIC1a interactome.

biophysics↗

bioRxiv2025

Allosteric factors in the calcium/calmodulin-responsive kinase II hub domain determine selectivity of GHB ligands for CaMKIIa

The Ca2+/CaM-dependent protein kinase II alpha (CaMKII) is a highly important synaptic protein, which comprises a unique holoenzyme structure organized via the central hub domain. Recently, a distinct binding pocket in the CaMKII hub domain was identified for the endogenous neuromodulator {gamma}-hydroxybutyric acid (GHB) and related synthetic analogues. Key interacting residues in CaMKII were revealed, but the pronounced selectivity towards the alpha variant of CaMKII has remained unresolved. Aimed at elucidating the molecular determinants for this selectivity, we here conducted binding studies to CaMKII-HEK whole-cell homogenates using two different in-house-developed GHB-related radioligands, [3H]HOCPCA and [3H]O-5-HDC, in combination with site-directed mutagenesis. Binding to CaMKII with the smaller-type radioligand [3H]HOCPCA validated key involvement of the four known residues (His395, Arg433, Arg453 and Arg469), but also revealed a role for the upper hub flexible loop containing the CaMKII-specific residue Trp403 (Leu in all other CaMKII isozymes). Insertion of the corresponding residues (L467W/C533R) into CaMKII{beta} failed to introduce [3H]HOCPCA binding. However, with the larger-type radioligand, [3H]O-5-HDC, specific binding in CaMKII{beta} (L467W/C533R) was achieved. Thus, of the four native CaMKII isozymes, only CaMKII accommodates GHB ligands. The study identifies the CaMKII flexible pocket loop as a distantly located "allosteric" factor in determining selectivity of GHB analogues for CaMKII. It sheds light on a remarkable interplay of the entire hub cavity for accommodation of ligands, and corroborates GHB analogues as CaMKII-selective.

biochemistry↗

bioRxiv2024

Proteochemometric modeling strengthens the role of Q299 for GABA transporter subtype selectivity

Proteochemometric modeling (PCM) combines ligand information as well as target information in order to predict an output variable of interest (e.g. activity of a compound). The big advantage of PCM compared to conventional Quantitative Structure-Activity Relationship (QSAR) modeling is, that by creating a single model one can not only predict the affinity of a diverse set of compounds to a diverse set of targets, but also extrapolate the specific ligand-protein interactions that might be relevant for activity. In this study, we compiled a dataset of 323 compounds and their bioactivity data regarding the inhibition of the four GABA-transporter (GAT1/BGT1/GAT2/GAT3) subtypes, which are potential new drug targets for treating epilepsy. Proteochemometric modeling using partial least squares and random forest provided models which performed equally well than conventional QSAR models for each individual transporter. However, by analyzing the importance of the protein descriptors used in the PCM models, we identified the amino acid Leu300/Q299/L294/L314/ in GAT1/BGT1/GAT2/GAT3 to be relevant for binding and subtype selectivity.

pharmacology and toxicology↗

bioRxiv2019

A widespread role for SLC transmembrane transporters in resistance to cytotoxic drugs

The activity and potency of a drug is inherently affected by the metabolic state of its target cell. Solute Carriers (SLCs) represent the largest family of transmembrane transporters in humans and constitute major determinants of cellular metabolism. Several SLCs have been shown to be required for the uptake of individual chemical compounds into cellular systems, but systematic surveys of transporter-drug relationships in human cells are currently lacking. We performed a series of genetic screens in the haploid human cell line HAP1 using a set of 60 cytotoxic compounds representative of the chemical space populated by approved drugs. By using a SLC-focused CRISPR/Cas9 lentiviral library, we identified transporters whose absence induced resistance to the drugs tested. Among the hundreds of drug-SLC relationships identified, we confirmed the role of the folate transporter SLC19A1 on the activity of antifolates and of SLC29A1 on several nucleoside analogs. Among the newly discovered dependencies, we identified the transporters SLC11A2/SLC16A1 for artemisinin derivatives and SLC35A2/SLC38A5 for cisplatin. The functional dependence on SLCs observed for a significant proportion of the compounds screened suggested a widespread role for SLCs in the uptake and cellular activity of cytotoxic drugs and provided an experimentally validated set of SLC-drug associations for a number of clinically relevant compounds.

cell biology↗