Biology subjects

Sych, T.

Publications and source records attributed to Sych, T..

11 recordsLinked to original sources

bioRxiv2026

Dehydration triggers anomalous subdiffusion in biomimetic cell membranes

Lipid diffusion plays a central role in shaping the structural organization of cell membranes, maintaining lipid homeostasis, and facilitating cellular transport and signaling. The lateral mobility of phospholipids in membranes depends heavily on their hydration state. Furthermore, the activation energy of diffusion increases in conditions of reduced membrane hydration, suggesting that the underlying diffusion mechanism changes upon dehydration. Using two variants of fluorescence correlation spectroscopy (point FCS and scanning FCS) and two membrane reporters, we demonstrate that mild dehydration of phase-separated biomimetic cell membranes alters the lipid diffusion mechanism, resulting in anomalous subdiffusion rather than free Brownian motion. Importantly, the anomalous diffusion parameter, , decreases significantly upon the initial reduction of the membrane hydration layer, and the effect is fully reversible upon rehydration. These observations strongly indicate the reversible shift in lipid diffusion mode rather than irreversible membrane damage. We propose that this anomalous subdiffusion is caused by the formation of temporarily immobile lipid pockets in the membrane upon dehydration. These results therefore provide important insights into the mechanism of lipid diffusion in membranes undergoing local and transient dehydration, which is an important intermediate step in various biological processes associated with membrane fusion, such as neurotransmission, fertilization, and viral entry.

biophysics↗

bioRxiv2026

Cell surface remodeling caused by the loss of TMEM30A in immune cells

Plasma membrane lipid asymmetry is tightly regulated and fundamental to mammalian cell physiology. TMEM30A is the {beta}-subunit of P4-ATPases, flippase enzymes that maintain strict phosphatidylserine (PS) asymmetry by pumping it from the outer to the cytosolic leaflet. Loss of TMEM30A function causes constitutive PS externalization and has been implicated in diseases such as diffuse large B-cell lymphoma and tumour immune evasion. Here, we systematically define the biophysical and molecular consequences of TMEM30A deletion in immune cells. Using a live-cell lipid reporter, membrane order probe, and surface proteome mapping, we show that TMEM30A-knockout cells display robust PS externalization accompanied by faster lateral diffusion of membrane constituents and decreased plasma membrane order. Surface proteome reorganization includes increased abundance of tetraspanins and CD47. Further, TMEM30A loss triggers glycocalyx remodeling via ADAM10-dependent shedding that removes major transmembrane mucins, including CD43 and CD162. Together, these data reveal a coordinated reorganization of lipids, glycans, and proteins upon TMEM30A loss, suggesting mechanistic links between flippase dysfunction and increased plasma membrane dynamics and potential sensitization to immune therapy. Furthermore, our study provides an integrated surfaceome framework that might shed light on the relationship between TMEM30A expression and clinical outcomes in cancer.

immunology↗

bioRxiv2025

LipiGo: A Versatile DNA-Lipid Nanoparticle Hybrid for Precision Drug Delivery

Lipid nanoparticles (LNPs) are established carriers for nucleic acid delivery, however, achieving efficient delivery to non-hepatic tissues remains a major challenge. Here, we present LipiGo, a nanocarrier platform engineered by integrating short single stranded DNA molecules into the lipid nanoparticle structure. Using whole body tissue clearing, advanced imaging and AI-based analysis, we show that LipiGo redirects functional mRNA delivery to lymphoid organs, particularly the spleen. Immune cell profiling further reveals enhanced uptake within key immune populations, including antigen-presenting cells, compared to standard LNPs. Beyond passive redistribution, LipiGo leverages DNA hybridization to enable modular attachment of targeting ligands for active targeting as demonstrated by cell-specific delivery to white adipocytes. Overall, the dual-purpose design principle of LipiGo demonstrates high modularity and efficiency, enabling tissue and cell specific delivery beyond hepatic applications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/676334v2_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@9b69eorg.highwire.dtl.DTLVardef@1b45bd0org.highwire.dtl.DTLVardef@1f7b79dorg.highwire.dtl.DTLVardef@37a673_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Pretreatment with estrogen enhances the therapeutic efficacy of cardiac progenitor cells and improves cardiac recovery in a failing heart model

BackgroundIn recent years, cardiac progenitor cells (CPCs) are considered as a potential source of cell therapy for the treatment of heart failure. Despite the encouraging results of clinical trials showing that transplantation of CPCs improves function of infarcted hearts, reduced cell survival and inefficient engraftment into host tissue are still challenging issues. MethodsCPCs were isolated from a male mouse heart and incubated with estrogen (10-7M for 48 hours) in vitro. The heart failure model was generated by intraperitoneally isoproterenol (ISO) treatment (200mg/kg for 6 days) in the female mouse. Either estrogen pretreated-CPC (E2-CPC) or untreated-CPCs (Control-CPC) were intramyocardially transplanted into the failure heart. Engraftment of transplanted cells were visualized by in vivo imaging, Y-chromosome staining (by Fluorescence In Situ Hybridization) and SRY gene for expression analysis. Cardiac functions were determined by analyzing electrophysiological changes. Pathological changes following the transplantation were also examined at the molecular level by immunostaining and western blotting from isolated heart samples and on heart tissue sections to address the efficiency of the E2-CPC transplantation. In addition to regenerative outcomes at animal level, the enhancing effect of estrogen on the therapeutic potential of CPC was examined through changes in migration, proliferation and mitochondrial energetics by in vitro experiments. The effects of estrogen in transcriptome profiling was also evaluated by RNA sequencing (RNA-seq) in CPCs. ResultsIn vivo results demonstrated that estrogen pretreatment increased the retention rate of transplanted CPCs in failing heart. E2-CPC transplantation enhanced cardiac function and ameliorated pathological cardiac remodelling via inducing revascularization, proliferation while attenuating collagen formation and hypertrophy in failing heart. Our in vitro results have shown that estrogen treatment promotes migration, angiogenesis and proliferation capacities and adenosine triphosphate (ATP) production of CPCs in vitro. RNA sequencing provided further evidence that the change in the transcriptome profile of CPCs upon estrogen treatment improved their ability to cause reverse cardiac remodelling in the failing heart after transplantation. ConclusionOur data indicated that estrogen-pretreatment significantly improves cardiac recovery in a failing heart through enhancing efficacy of CPC transplantation. This study also emphasized underyling mechanisms of the improvement in function in CPC-based therapies which remain poorly understood.

molecular biology↗

bioRxiv2025

Sheathless elasto-inertial focusing of sub-25 nm particles in straight microchannels

Nanoscale biological particles, such as lipoproteins (10-80 nm) or extracellular vesicles (30-200 nm), play pivotal roles in health and disease, including conditions like cardiovascular disorders and cancer. Their effective analysis is crucial for applications in diagnostics, quality control, and nanomedicine development. While elasto-inertial focusing offers a powerful method to manipulate particles without external fields, achieving consistent focusing of nanoparticles (<500 nm) has remained a challenge. In this study, we experimentally demonstrate elasto-inertial focusing of nanoparticles as small as 25 nm using straight high-aspect-ratio microchannels in a sheathless flow. Systematic investigations reveal the influence of channel width, particle size, viscoelastic concentration, and flow rate on focusing behavior. Additionally, through numerical simulations and experimental validation, we provide insights into particle migration dynamics and viscoelastic forces governing nanoparticle focusing. Finally, we successfully focus biological particles, including liposomes (90-140 nm), extracellular vesicles (100 nm), and lipoproteins (10-25 nm), under optimized conditions, showcasing potential applications in medical diagnostics and targeted drug delivery. These findings mark a significant advancement toward size-based high-resolution particle separation, with implications for biomedicine and environmental sciences.

bioengineering↗

bioRxiv2024

Imaging single particle profiler to study nanoscale bioparticles using conventional confocal microscopy

Single particle profiler is a unique methodology to study nanoscale bioparticles such as liposomes, lipid nanoparticles, extracellular vesicles and lipoproteins in single particle and high throughput manner. The original version requires the single photon counting modules for data acquisition. Here, we present imaging-based SPP (iSPP) which can be performed by imaging a spot over time in common imaging mode with photomultiplier tubes. We also provide a user-friendly software with graphical user interface to facilitate the application of this technique. We demonstrate that iSPP can be used to decipher lipid-protein interactions, membrane modifications by drugs and the heterogeneity of extracellular vesicles isolated from cells lines and urine of human donors.

biophysics↗

bioRxiv2023

A cholesterol switch controls phospholipid scrambling by G protein-coupled receptors

Class A G protein-coupled receptors (GPCRs), a superfamily of cell membrane signaling receptors, moonlight as constitutively active phospholipid scramblases. The plasma membrane of metazoan cells is replete with GPCRs, yet has a strong resting trans-bilayer phospholipid asymmetry, with the signaling lipid phosphatidylserine confined to the cytoplasmic leaflet. To account for the persistence of this lipid asymmetry in the presence of GPCR scramblases, we hypothesized that GPCR-mediated lipid scrambling is regulated by cholesterol, a major constituent of the plasma membrane. We now present a technique whereby synthetic vesicles reconstituted with GPCRs can be supplemented with cholesterol to a level similar to that of the plasma membrane and show that the scramblase activity of two prototypical GPCRs, opsin and the {beta}1-adrenergic receptor, is impaired upon cholesterol loading. Our data suggest that cholesterol acts as a switch, inhibiting scrambling above a receptor-specific threshold concentration to disable GPCR scramblases at the plasma membrane.

biochemistry↗

bioRxiv2022

Single particle profiler for measuring properties of nano-sized bioparticles

It is technically challenging to study the content and properties of nanoscale bioparticles in a high-throughput and single-molecule manner. We developed a high-throughput analysis method, called single particle profiler (SPP) that provides single-particle information on content and biophysical properties of thousands of particles. We applied SPP to measure the mRNA encapsulation efficiency of lipid nanoparticles, viral binding efficiency of different nanobodies and biophysical heterogeneity of liposomes, lipoproteins, exosomes and viruses.

biophysics↗

bioRxiv2022

The bacterial lectin LecA from P. aeruginosa alters membrane organization by dispersing ordered domains

The assembly and dynamic reorganization of plasma membrane nanodomains (also known as "lipid rafts") play key roles in host cell infection by human pathogens (e.g. viruses and bacteria). Viruses and bacteria can trigger the reorganization of lipid rafts which leads to membrane invaginations and downstream signaling that promote infection. Such reorganizations can be induced by interactions of bacterial or viral carbohydrate proteins (so-called lectins) with lipid raft glycosphingolipids (GSLs). Here, we studied the GSL globotriaosylceramide (Gb3) which is a key receptor involved in the cellular uptake of the gram-negative bacterium P. aeruginosa. The bacterial surface lectin LecA targets Gb3 and promotes bacterial invasion via the "lipid zipper" mechanism. However, the impact of LecA on the organization of membrane nanodomains is unknown yet. We mimicked of the plasma membrane using supported lipid bilayers (SLBs) that contained liquid-ordered (Lo, "raft-like", enriched in sphingolipids and GSLs) and liquid-disordered (Ld, "non-raft-like" enriched in DOPC) lipid domains. Upon interaction with LecA, the Lo domains in the SLBs reshaped and dispersed. Moreover, deformation of SLBs was observed as LecA formed membrane multilayers on SLBs surface. We further dissected this process to reveal the impact of Gb3 structure, bilayer composition and LecA valence on the Lo reorganization.

biophysics↗

bioRxiv2021

The influence of the extracellular domains on the dynamic behavior of membrane proteins

The dynamic behavior of plasma membrane proteins mediates various cellular processes such as cellular motility, communication, and signaling. It is widely accepted that the dynamics of the membrane proteins is determined either by the interactions of the transmembrane domain with the surrounding lipids or by the interactions of the intracellular domain with cytosolic components such as cortical actin. Although initiation of different cellular signaling events at the plasma membrane has been attributed to the extracellular domain (ECD) properties recently, the impact of ECDs on the dynamic behavior of membrane proteins is rather unexplored. Here, we investigate how the ECD properties influence protein dynamics in the lipid bilayer by reconstituting ECDs of different sizes or glycosylation in model membrane systems and analyzing ECD-driven protein sorting in lipid domains as well as protein mobility. Our data shows that increasing the ECD mass or glycosylation leads to a decrease in ordered domain partitioning and diffusivity. Our data reconciles different mechanisms proposed for the initiation of cellular signaling by linking the ECD size of membrane proteins with their localization and diffusion dynamics in the plasma membrane. SIGNIFICANCE STATEMENTWe studied how the size and glycosylation of the proteins influences their dynamic behavior in a lipid bilayer by reconstituting the ECDs of different sizes or glycosylation in model membrane systems and analyzing their sorting into lipid domains as well as their mobility. We observe that increasing the ECD apparent mass leads to a decrease in membrane ordered domain partitioning and diffusivity. Our data reconciles multiple mechanisms proposed for the initiation of cellular signaling by linking the ECD properties of membrane proteins with their localization and diffusion dynamics in the plasma membrane.

biophysics↗

bioRxiv2020

Lipoprotein particles interact with membranes and transfer their cargo without receptors

Lipid transfer from lipoprotein particles to cells is essential for lipid homeostasis. High density lipoprotein (HDL) particles are mainly captured by cell-membrane-associated scavenger receptor class B type 1 (SR-B1) from the blood stream while low and very low density lipoprotein (LDL, VLDL) particles are mostly taken up by receptor-mediated endocytosis. However, the role of the target lipid membrane itself in the transfer process has been largely neglected so far. Here, we study how lipoprotein particles (HDL, LDL and VLDL) interact with synthetic lipid bilayers and cell-derived membranes and transfer their cargo subsequently. Employing cryo-electron microscopy, spectral imaging and fluorescence (cross) correlation spectroscopy allowed us to observe integration of all major types of lipoprotein particles into the membrane and delivery of their cargo in a receptor-independent manner. Importantly, biophysical properties of the target cell membranes change upon cargo delivery. The concept of receptor-independent interaction of lipoprotein particles with membranes helps to better understand lipoprotein particle biology and can be exploited for novel treatments of dyslipidemia diseases.

biophysics↗