Plasma Membrane Research Articles

The Epitome of Antioxidants Against UV Photodamage: Vitamin E Use in Skin Protection

Since its discovery, there has been ongoing discourse regarding the physiological significance and therapeutic potential of vitamin E, particularly in combating cell damage caused by free radicals. As a prominent antioxidant in the body, vitamin E plays a crucial role in reducing lipid peroxidation within cell membranes, making it a focal point for researchers in dermatology. The unique cellular functions of vitamin E have been linked to its antitumorigenic and photoprotective properties, garnering attention for its potential efficacy in addressing UV-related skin conditions. This literature review aims to illuminate the efficacy of vitamin E, spanning its topical applications to oral supplementation for the protection against photodamage, through an examination of past research in dermatology. A comprehensive analysis of 44 studies from the PubMed database and ScienceDirect, spanning from 1990 to 2022 and references up to 2024, was conducted to gather insights from clinical trials and investigations focusing on potential therapeutic uses of vitamin E in managing UV-induced skin disorders. This review article includes a diverse range of studies-such as experimental research, randomized controlled trials, clinical studies, and double-blind trials-to comprehensively examine the wide-ranging effects of Vitamin E in protecting against UV-induced photodamage. This includes photodamage, nonmelanoma skin cancer, radiodermatitis, and age-related skin changes.

Gasdermin-D pores induce an inactivating caspase-4 cleavage that limits IL-18 production in the intestinal epithelium

Intestinal epithelial-derived IL-18 is critical for homeostatic intestinal barrier function and is secreted through Gasdermin D (GSDMD) pores. Inflammasome activation is a prerequisite for both IL-18 maturation and GSDMD pore formation. However, GSDMD pores also cause pyroptotic cell death, which could be detrimental to the intestinal epithelial barrier. How epithelial cells balance the need to secrete IL-18 and to maintain barrier integrity remains poorly understood. In human intestinal epithelial cell lines and in primary human epithelial intestinal organoids, but not in immune cells, GSDMD plasma membrane pore formation by LPS electroporation and by gram-negative bacterial infection induced a non-conventional p37 caspase-4 fragment that was associated with reduced levels of mature IL-18. By contrast, limiting GSDMD plasma membrane pores pharmacologically and via point-mutagenesis prevented caspase-4 cleavage and increased IL-18 production, suggesting that p37 caspase-4 cleavage may regulate IL-18 maturation in the intestinal epithelium. In support, co-expression of caspase-4 cleavage mutants and IL-18 in HEK293T cells revealed that non-cleavable caspase-4 produced more mature IL-18 than cleaved caspase-4. Overall, these studies suggest that epithelial inflammasomes encode feedback pathways that control the balance between cytokine secretion and cell death. This may be an important mechanism to ensure homeostatic IL-18 production in the intestinal epithelium.

Intracellular Delivery Enabled by Squeezing Mechanoporation.

Squeeze mechanoporation, as an emerging method, plays an important role in intracellular delivery. It brings new opportunities to cutting-edge fields such as cell therapy, gene editing, and vaccine production, and it promises to revolutionize traditional drug delivery and treatment paradigms. By leveraging the viscoelastic properties of cells, this technique induces cell deformation under external force, creating transient micropores in cell membranes for the efficient and high-throughput delivery of diverse exogenous substances, such as nucleic acids, antibodies, nanomaterials, and drugs. This review comprehensively summarizes current advances in mechanical squeezing-mediated intracellular delivery, delving deeply into its fundamental principles, unique advantages, latest applications, optimization strategies, existing challenges, corresponding solutions, and future development directions. With the aim of highlighting the immense potential and promising prospects of these techniques in the field of biomanufacturing and celltherapy.

Semaglutide Aggregates into Oligomeric Micelles and Short Fibrils in Aqueous Solution.

Semaglutide is a lipopeptide with important applications in the treatment of diabetes, obesity, and other conditions. This class of drug (glucagon-like peptide-1 agonists and other lipidated peptides) may be susceptible to aggregation due to the tendency of lipopeptides to self-assemble into various nanostructures. Here, we show using cryogenic-TEM, small-angle X-ray scattering, and molecular dynamics simulations that semaglutide in aqueous solution undergoes slow aggregation into spherical micelles in water at sufficiently high concentration. A small population of needle-shaped fibril aggregates is also observed. At a lower concentration, dimer and trimer structures are formed. The micelles, once formed, are stable toward further aging. The aggregation influences the effect of semaglutide on the permeability of an epithelial gut model membrane of Caco-2 cells. These findings are expected to be important in understanding the long-term stability of semaglutide solutions and the potential effects of aggregation on therapeutic efficacy.

Annexin, a Protein for All Seasons: From Calcium Dependent Membrane Metabolism to RNA Recognition.

Annexins are a protein family well known to bind to phospholipids in a calcium-dependent way. They are involved in several different crucial cellular processes such as cell division, calcium signaling, membrane repair, vesicle trafficking, and apoptosis. Although RNA binding for some members of the family was reported long ago, it was only recently that it was shown that a common feature of the family is also the ability to bind RNA, a discovery that has added significantly to our perception of the cellular role of these proteins. In the present review, we discuss the properties of annexins under an updated light and the current knowledge on the RNA binding properties of annexins. We then focus specifically on annexin A11, because this is a less characterized member of the family but, at the same time, a potentially important component of the mRNA transport machinery in neurons. We hope to offer to the reader a more complete picture of the annexins' binding properties and new tools to evaluate the multifaceted functions of this important protein family.

METTL3 promotes gastric cancer progression via modulation of FNTA-mediated KRAS/ERK signaling activation.

As a vital form of post-transcriptional modification, RNA N6-methyladenosine methylation (m6A) dysregulation is usually associated with the pathogenesis of a range of diseases, including cancer, but the function and underlying mechanisms of m6A in regulating gastric cancer initiation and progression are still poorly understood. Here, we have found methytransferase like 3 (METTL3) and the level of RNA m6A modification were significantly upregulated in gastric cancerous tissues relative to their normal counterparts. In addition, higher METTL3 expression always predicted poorer outcomes for patients with gastric cancer. Methylated RNA sequencing revealed that METTL3 deposited m6A modification on FNTA (farnesyltransferase, subunit alpha) mRNA and accelerated its translation relying on YTH N6-methyladenosine RNA binding protein 1 (YTHDF1) recognition. When METTL3 or FNTA expression was silenced in gastric cancer cells, the FNTA-mediated KRAS plasma membrane distribution was disrupted, resulting in downstream MEK/ERK signaling inactivation, which finally contributed to gastric cancer suppression in vitro and in vivo. In summary, our studies revealed a crosstalk between METTL3-mediated RNA methylation and FNTA-mediated protein modification which synergized to drive gastric cancer progression through orchestrating KRAS/ERK signaling activity. Implications: Targeting METTL3/FNTA pathway will provide an alternative to overcome the resistance of gastric cancer to canonical KRAS inhibitors.

Mechanisms for enhancing ethanol tolerance of Saccharomyces cerevisiae through nano-selenium supplementation during Chinese rice wine brewing.

The toxic environment created by elevated ethanol levels presents significant challenges to Saccharomyces cerevisiae, leading to incomplete fermentation of the raw materials, poor flavor of the product, and even increased difficulty in post-processing of the product. Therefore, enhancing the ethanol tolerance and metabolic capacity of strains is critical for the brewing of Chinese rice wine. Results revealed that 1-3 mg L-1 nano-selenium significantly increased viable bacteria counts, reproduction rates and antioxidant enzyme activities, while reducing malondialdehyde levels and lipid peroxidation of S. cerevisiae. Notably, a concentration of 2 mg L-1 nano-selenium improved the cell membrane integrity and morphology under ethanol stress. Transcriptome analysis revealed that nano-selenium influenced gene expression related to cell wall repair, ribosome synthesis, carbon cycle and energy metabolism, and stress response. These changes represent a coordinated response to ethanol stress, enhancing the ability of yeast to cope with ethanol stress. Our results indicated that an optimal concentration of nano-selenium can effectively boost the metabolic capacity of S. cerevisiae, improving fermentation efficiency and product quality. © 2025 Society of Chemical Industry.

Physiological and biochemical responses of cotton (Gossypium hirsutum) seedlings to NaCl stress and analysis of salt tolerance thresholds.

Soil salinisation is increasing in extent and area, which seriously limits the growth of crops. In this experiment, we investigated the differences in physiological responses and salt (NaCl) tolerance thresholds between salt-tolerant ('Xinluzao 53') and salt-sensitive ('Xinluzao 60') varieties of cotton (Gossypium hirsutum ). Peroxidase activity of 'Xinluzao 53' and 'Xinluzao 60' increased by 29.37% and 59.35%, compared with the control, respectively. Catalase activity of 'Xinluzao 53' and 'Xinluzao 60' was 101.00% and 61.59% higher than that of the control, respectively. Overall increase of malondialdehyde (MDA) content in the leaves of 'Xinluzao 53' was less than 'Xinluzao 60', which was lower in 'Xinluzao 53' than 'Xinluzao 60' under the salt treatments of 8g kg-1 (32.59% lower) and 10g kg-1 (35.27% lower). Net photosynthetic rate (Pn) of 'Xinluzao 60' was reduced by 13.31%, 22.83%, and 21.52% compared to 'Xinluzao 53' at salt concentrations of 2, 8, and 10g kg-1 , respectively. 'Xinluzao 53' protected the cell membrane structure by maintaining higher antioxidant enzyme activities, lower MDA content, and electrolyte leakage under salt stress. Higher SPAD values, chlorophyll fluorescence parameters and photosynthetic rates were further maintained to safeguard normal physiological metabolism and photosynthetic system, higher salt tolerance than 'Xinluzao 60'. The orrelation analysis and quadratic regression equation established an integrated, comprehensive, and reliable screening method for cotton seedling salt tolerance threshold in combination with the actual growth of seedlings. The salt tolerance threshold of salt-tolerant 'Xinluzao 53' seedlings was 10.1g kg-1 , and the salt tolerance threshold of sensitive 'Xinluzao 60' seedlings was 8.5g kg-1 .

The Role of a Glucal-Based Molecule in the Reduction of Pancreatic Adenocarcinoma—An In Vitro and In Silico Approach

Background/Objectives: Pancreatic cancer is the seventh most lethal type of cancer in the world, and its treatment, which is largely inefficient, is based on surgery and/or non-specific chemotherapy. Its malignant features are characterized by complex cell signaling pathways, which can be used as targets for new drugs. Methods: In this study, glucal-based compounds were synthetized, with substitution based on fluorine, nitrogen and aromatic ring addition. The compounds were tested in the pancreatic cell culture Mia-PaCa-2 and cell viability was assessed, with further IC50 calculation, stability and selectivity. Molecular docking was performed to evaluate the probable molecular target for 5b and in silico physicochemical properties were determined. Results: One molecule, named 5b, with two fluorine atoms inserted in the aromatic ring, exerted potent inhibitory activity on cell growth (IC50 = 1.39 µM), which was selective for pancreatic cells. Through molecular docking studies, the compound was found to be positioned in the active site of JAK3, indicating inhibition of such protein, which has a role in tumoral cell growth. Moreover, 5b was stable for 24 months and had physicochemical properties to permeate cell membranes, good oral absorption, and low potential to cause toxicity. Conclusions: These data suggest that 5b can be druggable and can be considered as a prototype for a new course of treatment in pancreatic cancer.

Refining Single-Atom Catalytic Kinetics for Tumor Homologous-Targeted Catalytic Therapy

Single-atom nanozymes (SAzymes) hold significant potential for tumor catalytic therapy, but their effectiveness is often compromised by low catalytic efficiency within tumor microenvironment. This efficiency is mainly influenced by key factors including hydrogen peroxide (H2O2) availability, acidity, and temperature. Simultaneous optimization of these key factors presents a significant challenge for tumor catalytic therapy. In this study, we developed a comprehensive strategy to refine single-atom catalytic kinetics for enhancing tumor catalytic therapy through dual-enzyme-driven cascade reactions. Iridium (Ir) SAzymes with high catalytic activity and natural enzyme glucose oxidase (GOx) were utilized to construct the cascade reaction system. GOx was loaded by Ir SAzymes due to its large surface area. Then, the dual-enzyme-driven cascade reaction system was modified by cancer cell membranes for improving biocompatibility and achieving tumor homologous targeting ability. GOx catalysis reaction could produce abundant H2O2 and lower the local pH, thereby optimizing key reaction-limiting factors. Additionally, upon laser irradiation, Ir SAzymes could raise local temperature, further enhancing the catalytic efficiency of dual-enzyme system. This comprehensive optimization maximized the performance of Ir SAzymes, significantly improving the efficiency of catalytic therapy. Our findings present a strategy of refining single-atom catalytic kinetics for tumor homologous-targeted catalytic therapy.

Piezo Channels in Dentistry: Decoding the Functional Effects of Forces.

The oral system is a highly complex mechanosensory structure that continuously adapts to changes in mechanical stimuli, exerting mechanical forces on cells and tissues. Understanding how these forces are converted into biochemical signals and how they mediate gene expression and cellular activities has been a significant focus in dentistry. Piezo channels, including Piezo1 and Piezo2, are mechanically activated cation channels characterized by an extracellular "cap" domain and 3 peripheral mechanosensitive blades. Recent research has demonstrated that mechanical forces applied to tissues can induce deformation of cell membranes, leading to conformational changes in Piezo channels that facilitate cation influx, thereby regulating cellular activities. The influx of Ca2+, the most discussed outcome of Piezo channel activation, initiates diverse signaling pathways that regulate dentin hypersensitivity, alveolar bone remodeling, and temporomandibular joint (TMJ) osteoarthritis. The chemical inhibition of Piezo channels has been shown to alleviate dentinal hypersensitivity, reduce the rate of orthodontic tooth movement, and slow the progression of TMJ osteoarthritis in rat models. Mice deficient in piezo channels exhibit impaired reactive dentin formation, reduced alveolar bone volume, and developmental deformities of the jawbone. Considering their roles in decoding the functional effects of mechanical forces, this review summarizes the involvement of Piezo channels in dentistry, organized by anatomical sites, to provide comprehensive knowledge of Piezo channels and their mediated signal crosstalk, which offers promising therapeutic prospects for the treatment of various force-related oral diseases.

Fusogenic Lipid Nanovesicles as Multifunctional Immunomodulatory Platforms for Precision Solid Tumor Therapy.

Although immunotherapy demonstrates considerable prospect in overcoming solid tumors, its clinical efficacy is limited by several factors, such as poor tumor immunogenicity, inadequate immune activation, and immunosuppressive tumor microenvironment (TME). To overcome these challenges, a versatile and universal immune modulation platform should be developed, and lipid nanovesicles with membrane fusion capabilities (LNV-Fs) have attracted great attention for this purpose. By mimicking natural membrane fusion processes, LNV-Fs enable the precise presentation of immunogenic components on tumor cell membranes, effectively activating anti-tumor immune surveillance. Similarly, LNV-Fs can equip multiple functionalities on autologous and adoptive effector cells for enhanced cell therapies. Additionally, LNV-Fs function as vaccines that elicit robust autologous anti-tumor immunity while promoting long-term immune memory. Furthermore, different LNV-Fs with powerful ability in reprogramming TME have been reported. Given the recent advancements and the absence of comprehensive reviews on this topic, a comprehensive analysis of LNV-F systems, including their structural classifications, membrane fusion mechanisms, and recent applications in cancer immunotherapy is provided. Furthermore, the future prospects of LNV-Fs, with particular emphasis on artificial intelligence-assisted design are explored. This review is intended to engage researchers from diverse interdisciplinary fields and provide valuable insights for advancing precision immunotherapy.

Digoxin promotes anoikis of circulating cancer cells by targeting Na+/K+-ATPase α3-isoform

Abstract Circulating cancer cells (CCCs) are closely related to the process of distant metastasis. In early step of the metastasis cascade, CCCs must evade the detachment-induced cell death (anoikis) for their survival. Here, we examined whether Na+/K+-ATPase α3-isoform (α3NaK) in CCCs contributes to avoidance of anoikis. In CCCs isolated from gastric cancer patients, α3NaK was predominantly localized in the plasma membrane (PM), but it moved to the cytoplasm when the CCCs were attached to culture dishes. The CCCs showed significant expression of integrin α5 but not fibronectin, one of components of the extracellular matrix (ECM). In human gastric cancer MKN45 cells, digoxin (20 and 50 nM), a cardiac glycoside, significantly inhibited the enzyme activity and translocation (from cytoplasm to PM) of α3NaK, while they had no significant effect on ubiquitous Na+/K+-ATPase α1-isoform (α1NaK) in the PM. The translocation of α3NaK required the loss of ECM components from the cells. Additionally, digoxin significantly enhanced caspase 3/7 activity, as well as the expression of cleaved caspase 3, while reducing the viability of detached (floating) cells. In the MKN45 xenograft mouse model, intraperitoneal administration of digoxin (2 mg/kg/day) significantly decreased the number of CCCs and suppressed their liver metastasis. Our results suggest that α3NaK plays an essential role in the survival of CCCs in gastric cancer, and that digoxin enhances anoikis in detached (metastatic) gastric cancer cells by inhibiting the α3NaK translocation from cytoplasm to PM, thereby reducing CCCs. Targeting α3NaK may be a promising therapeutic strategy against CCC survival.

Label-Free Quantification of Nanoplastic-Cell Membrane Interaction by Single Cell Deformation Plasmonic Imaging.

Nanoplastics are a growing environmental concern due to their potential to disrupt cellular functions. Understanding how these particles interact with cell membranes is crucial for assessing their biological effects. In this study, we present a label-free, quantitative method─Single Cell Deformation Plasmonic Imaging (SCDPI)─to measure real-time membrane interaction dynamics at the single-cell level. By examining both fixed and live cells, we characterized the binding behaviors of nanoplastics with varying sizes, surface chemistries, and materials. Our findings show that nanoplastic binding induces cell membrane deformation ranging from a few to tens of nanometers, depending on nanoplastic type and concentration (0-250 μg/mL), influencing membrane-surface interactions. This work provides new mechanistic insights into nanoplastic-cell interactions, demonstrating the potential of SCDPI as a powerful tool for evaluating the cellular impacts of environmental pollutants.

The SlDOF9-SlSWEET17 Module: a Switch for Controlling Sugar Distribution Between Nematode Induced Galls and Roots in Tomato.

In the complex interactions between plants and pathogens, the regulation of nutrient allocation plays a critical role in determining plant health and susceptibility to diseases. Root-knot nematodes (RKNs, Meloidogyne incognita) extract sugar from plants during their interactions with the hosts. SWEET (Sugars Will Eventually be Exported Transporters) proteins are a class of non-energy-consuming sugar uniporters that regulate the allocation of sugars in plant. Here, it is find that SlSWEET17 (Solanum lycopersicum SWEET17), a member of the SWEET family in tomato, is localized to the plasma membrane, Golgi body and small vacuoles, and is highly expressed in galls. Further studies show that SlSWEET17 negatively regulates the sugar transport capacity of other SlSWEETs via protein interactions. Overexpression of SlSWEET17 significantly decreases the soluble sugar content in galls and susceptibility to RKNs, while SlSWEET17 knockout-mutation (ko-mutation) has the opposite effect. It is also identified SlDOF9 (Solanum lycopersicum DNA binding with one finger 9), an upstream negative regulator of SlSWEET17, using ChIP (chromatin immunoprecipitation) analysis, electrophoretic mobility shift assays and dual-Luciferase assays. SlDOF9-overexpressing plants show increased sugar content in galls and susceptibility to RKNs, and sldof9cr ko-mutants have the opposite phenotype. This results show how SlDOF9-SlSWEET17 affects RKN infection through sugar partitioning from roots to galls.

Exploring the antimicrobial potential of the articaine derivative in oral infections

ABSTRACT Objective Postoperative infection is one of the most common complications in dental procedures. During local anesthesia in dental treatments, the risk of postoperative infections increases if the oral mucosa is infected, the anesthesia injection site is inadequately disinfected, or the injection needle and anesthetic drugs are contaminated. Thus, developing new oral local anesthetics that offer superior anesthesia, enhanced safety, and antimicrobial properties could greatly enhance their clinical value. Methods The anesthetic effects and antibacterial properties of articaine derivatives were screened using membrane chromatography techniques, animal experiments, and cellular molecular assays. Safety assessments were conducted on the selected target compounds. Additionally, the antibacterial mechanisms of the compounds were investigated through molecular dynamics simulations and cryo-electron microscopy. Results Through the screening of articaine derivatives, a novel local anesthetic, AT-15, was identified, which combines effective anesthetic properties with antibacterial activity. This compound exhibits strong pharmacological activity and high safety. Its antibacterial effect is believed to result from the disruption of bacterial cell membranes and the inhibition of topoisomerase, an enzyme essential for bacterial DNA synthesis. Conclusion AT-15 discovered in this study is a promising candidate for further development in clinical settings.

Mesoporous Gold Nanospheres Confined Platinum Nanoclusters as Robust ROS and Oxygen Nanogenerators for NIR-II Hyperthermia Cancer Therapy.

While massive studies are focused on platinum (Pt)-based nanozyme for antitumor therapies, their therapeutic efficiency is deficient due to the weak catalytic activity in the highly complex tumor microenvironment. Herein, mesoporous gold nanospheres confined platinum nanoclusters (MGNSs@Pt) as robust hydroxyl radical and oxygen nanogenerators are achieved for multimodal therapies. Benefiting from the confinement effect of the mesopores in the MGNSs, the Pt nanoclusters (Pt NCs) demonstrate enhanced stability and catalytic activity, with a catalytic constant (Kcat) of 1.42×106s-1, which is 2 and 5 orders magnitude higher than Kcat values of Pt-decorated non-porous gold nanoparticles and pure Pt NCs respectively. Density functional theory (DFT) calculations reveal the proper interaction of intermediates contributes to the ultra-high catalytic activity of MGNSs@Pt. Meanwhile, owing to the local surface plasmon resonance (LSPR) effect in the second near-infrared (NIR-II) bio-window of MGNSs, the nanozymes exhibited high photothermal conversion efficiency up to 43.4%, which enhanced the nanocatalytic damage on cancer cells. This process can induce robust oxidative stress and oxygenation within the tumor, thereby activating the apoptosis pathway for tumor eradication by mitochondrial dysfunction, cell membrane disruption, HIF-1α downregulation as well as caspase 3 activation, which pave the way for multimodal and effective cancer treatment.

PATROL1-mediated H+-ATPase translocation boosts plant growth under drought by optimizing root and leaf functions

Abstract Optimizing leaf photosynthesis and root water and mineral uptake in crops during drought is crucial for enhancing agricultural productivity under climate change. Although plasma membrane H+-ATPase plays a key role in plant physiological processes, its overexpression alone does not consistently improve growth. While PROTON ATPASE TRANSLOCATION CONTROL 1 (PATROL1) regulates H+-ATPase translocation in response to various environmental stimuli in leaves, its function in roots remains largely unknown. Here we show that H+-ATPase was coimmunoprecipitated with PATROL1 in roots of Arabidopsis thaliana. Under hyperosmotic stress, PATROL1 overexpression line had significantly greater root length and lateral root numbers than wild type and knockout lines. Micrografting between wild type and PATROL1 knockout or overexpression lines showed that PATROL1 is indispensable in both shoots and roots, indicating that root uptake and leaf photosynthesis are simultaneous limiting factors for plant growth under soil water deficit. Compared to the wild type, PATROL1 overexpression in whole plants resulted in a 41% increase in shoot dry weight and a 43% increase in shoot nitrogen content under drought conditions. These findings highlight the potential of H+-ATPase regulation in both roots and shoots as a new strategy to improve plant productivity, particularly under drought conditions.

BiDAC-dependent degradation of plasma membrane proteins by the endolysosomal system

The discovery of bifunctional degradation activating compounds (BiDACs) has led to the development of a new class of drugs that promote the clearance of their protein targets. BiDAC-induced ubiquitination is generally believed to direct cytosolic and nuclear proteins to proteolytic destruction by proteasomes. However, pathways that govern the degradation of other classes of BiDAC targets, such as integral membrane and intraorganellar proteins, have not been investigated in depth. In this study we use morphological profiling and CRISPR/Cas9 genetic screens to investigate the mechanisms by which BiDACs induce the degradation of plasma membrane receptor tyrosine kinases (RTKs) EGFR and Her2. We find that BiDAC-dependent ubiquitination triggers the trafficking of RTKs from the plasma membrane to lysosomes for degradation. Notably, functional proteasomes are required for endocytosis of RTKs upstream of the lysosome. Additionally, our screen uncovers a non-canonical function of the lysosome-associated arginine/lysine transporter PQLC2 in EGFR degradation. Our data show that BiDACs can target proteins to proteolytic machinery other than the proteasome and motivate further investigation of mechanisms that govern the degradation of diverse classes of BiDAC targets.

Mapping the interaction surface between CaVβ and actin and its role in calcium channel clearance

Defective ion channel turnover and clearance of damaged proteins are associated with aging and neurodegeneration. The L-type CaV1.2 voltage-gated calcium channel mediates depolarization-induced calcium signals in heart and brain. Here, we determined the interaction surface between actin and two calcium channel subunits, CaVβ2 and CaVβ4, using cross-linking mass spectrometry and protein-protein docking, and uncovered a role in replenishing conduction-defective CaV1.2 channels. Computational and in vitro mutagenesis identified hotspots in CaVβ that decreased the affinity for actin but not for CaV1.2. When coexpressed with CaV1.2, none of the tested actin-association-deficient CaVβ mutants altered the single-channel properties or the total number of channels at the cell surface. However, coexpression with the CaVβ2 hotspot mutant downregulated current amplitudes, and with a concomitant reduction in the number of functionally available channels, indicating that current inhibition resulted from a build-up of conduction silent channels. Our findings established CaVβ2–actin interaction as a key player for clearing the plasma membrane of corrupted CaV1.2 proteins to ensure the maintenance of a functional pool of channels and proper calcium signal transduction. The CaVβ–actin molecular model introduces a potentially druggable protein-protein interface to intervene CaV-mediated signaling processes.