Transport Proteins Research Articles

Role of AcrAB-TolC and Its Components in Influx-Efflux Dynamics of QAC Drugs in Escherichia coli Revealed Using SHG Spectroscopy.

Multidrug efflux pumps, especially those belonging to the class of resistance-nodulation-division (RND), are the key contributors to the rapidly growing multidrug resistance in Gram-negative bacteria. Understanding the role of efflux pumps in real-time drug transport dynamics across the complex dual-cell membrane envelope of Gram-negative bacteria is thus crucial for developing efficient antibiotics against them. Here, we employ second harmonic generation-based nonlinear spectroscopy to study the role of the tripartite efflux pump and its individual components. We systematically investigate the effect of periplasmic adaptor protein AcrA, inner membrane transporter protein AcrB, and outer membrane channel TolC on the overall drug transport in live Acr-type Escherichia coli and its mutant strain cells. Our results reveal that when one of its components is missing, the tripartite AcrAB-TolC efflux pump machinery in Escherichia coli can effectively function as a bipartite system, a fact that has never been demonstrated in live Gram-negative bacteria.

Anaplasma phagocytophilum effector EgeA facilitates infection by hijacking TANGO1 and SCFD1 from ER–Golgi exit sites to pathogen-occupied inclusions

The obligatory intracellular bacterium Anaplasma phagocytophilum causes human granulocytic anaplasmosis, an emerging zoonosis. Anaplasma has limited biosynthetic and metabolic capacities, yet it effectively replicates inside of inclusions/vacuoles of eukaryotic host cells. Here, we describe a unique Type IV secretion system (T4SS) effector, ER-Golgi exit site protein of Anaplasma (EgeA). In cells infected by Anaplasma, secreted native EgeA, EgeA-GFP, and the C-terminal half of EgeA (EgeA-C)-GFP localized to Anaplasma-containing inclusions. In uninfected cells, EgeA-C-GFP localized to cis-Golgi, whereas the N-terminal half of EgeA-GFP localized to the ER. Pull-down assays identified EgeA-GFP binding to a transmembrane protein in the ER, Transport and Golgi organization protein 1 (TANGO1). By yeast two-hybrid analysis, EgeA-C directly bound Sec1 family domain-containing protein 1 (SCFD1), a host protein of the cis-Golgi network that binds TANGO1 at ER-Golgi exit sites (ERES). Both TANGO1 and SCFD1 localized to the Anaplasma inclusion surface. Furthermore, knockdown of Anaplasma EgeA or either host TANGO1 or SCFD1 significantly reduced Anaplasma infection. TANGO1 and SCFD1 prevent ER congestion and stress by facilitating transport of bulky or unfolded proteins at ERES. A bulky cargo collagen and the ER-resident chaperon BiP were transported into Anaplasma inclusions, and several ER stress marker genes were not up-regulated in Anaplasma-infected cells. Furthermore, EgeA transfection reduced collagen overexpression-induced BiP upregulation. These results suggest that by binding to the two ERES proteins, EgeA redirects the cargo-adapted ERES to pathogen-occupied inclusions and reduces ERES congestion, which facilitates Anaplasma nutrient acquisition and reduces ER stress for Anaplasma survival and proliferation.

Regulation of cannabinoid and opioid receptor levels by endogenous and pharmacological chaperones.

Cannabinoid and opioid receptor activities can be modulated by a variety of posttranslational mechanisms including the formation of interacting complexes. This study examines the involvement of endogenous and exogenous chaperones in modulating the abundance and activity of cannabinoid CB1 receptor (CB1R), delta opioid receptor (DOR), and CB1R-DOR interacting complexes. Focussing on endogenous protein chaperones namely receptor transporter proteins (RTPs), we examined relative mRNA expression in the mouse spinal cord and found RTP4 to be expressed at higher levels compared to other RTPs. Next, we assessed the effect of RTP4 on receptor abundance by manipulating RTP4 expression in cell lines. Overexpression of RTP4 causes an increase and knock-down causes a decrease in the levels of CB1R, DOR, and CB1R-DOR interacting complexes; this is accompanied by parallel changes in signaling. The ability of small molecule lipophilic ligands to function as exogenous chaperones was examined using receptor-selective antagonists. Long term treatment leads to increases in receptor abundance and activity with no changes in mRNA supporting a role as pharmacological chaperones. Finally, the effect of cannabidiol (CBD), a small molecule ligand and a major active component of Cannabis, on receptor abundance and activity in mice was examined. We find that CBD administration leads to increases in receptor abundance and activity in mouse spinal cord. Together, these results highlight a role for chaperones (proteins and small molecules) in modulating levels and activity of CB1R, DOR, and their interacting complexes potentially through mechanisms including receptor maturation and trafficking. Significance Statement This study highlights a role for chaperones (endogenous and small membrane-permeable molecules) in modulating levels of CB1R, DOR, and their interacting complexes. These chaperones could be developed as therapeutics for pathologies involving these receptors.

Integrated cellular response of the zebrafish (Danio rerio) heart to temperature change.

A decrease in environmental temperature represents a challenge to the cardiovascular system of ectotherms. To gain insight into the cellular changes that occur during cold exposure and cold acclimation we characterized the cardiac phosphoproteome and proteome of zebrafish following 24 h or one week exposure to 20 oC from 27 oC; or at multiple points during six weeks of acclimation to 20 oC from 27 oC. Our results indicate that cold exposure causes an increase in mitogen-activated protein kinase signaling, the activation of stretch sensitive pathways, cellular remodeling via ubiquitin-dependent pathways, and changes to the phosphorylation state of proteins that regulate myofilament structure and function including desmin and troponin T. Cold acclimation (2-6 weeks) led to a decrease in multiple components of the electron transport chain through time, but an increase in proteins for lipid transport, lipid metabolism, the incorporation of polyunsaturated fatty acids into membranes and protein turnover. For example, there was an increase in the levels of apolipoprotein C, prostaglandin reductase-3, and surfeit locus protein 4, involved in lipid transport, lipid metabolism, and lipid membrane remodeling. Gill opercular movements suggests that oxygen utilization during cold acclimation is reduced. Neither the amount of food consumed relative to body mass nor body condition were affected by acclimation. These results suggest that while oxygen uptake was reduced, energy homeostasis was maintained. This study highlights that the response of zebrafish to a decrease in temperature is dynamic through time and that investment in the proteomic response increases with the duration of exposure.

Active protein ubiquitination regulates xylem vessel functionality.

Xylem vessels function in the long-distance conduction of water in land plants. The NAC transcription factor VASCULAR-RELATED NAC-DOMAIN7 (VND7) is a master regulator of xylem vessel cell differentiation in Arabidopsis (Arabidopsis thaliana). We previously isolated suppressor of ectopic xylem vessel cell differentiation induced by VND7 (seiv) mutants. Here, we report that the responsible genes for seiv3, seiv4, seiv6, and seiv9 are protein ubiquitination-related genes encoding PLANT U-BOX46 (PUB46), an uncharacterized F-BOX protein (FBX), PUB36, and UBIQUITIN-SPECIFIC PROTEASE1 (UBP1), respectively. We also found decreased expression of genes downstream of VND7 and abnormal xylem transport activity in the seiv mutants. Upon VND7 induction, ubiquitination levels from 492 and 180 protein groups were up- and down-regulated, respectively. VND7 induction resulted in the ubiquitination of proteins for cell wall biosynthesis and protein transport, whereas such active protein ubiquitination did not occur in the seiv mutants. We detected the ubiquitination of three lysine residues in VND7: K94, K105, and K260. Substituting K94 with arginine significantly decreased the transactivation activity of VND7, suggesting that the ubiquitination of K94 is crucial for regulating VND7 activity. Our findings highlight the crucial roles of target protein ubiquitination in regulating xylem vessel activity.

Exploring intermolecular interaction between transporter protein, bovine serum albumin and antitumor drug Lorlatinib: Multispectral approaches combined with molecular simulation

In this paper, the intermolecular interaction of antitumor drug loratinib (LOR) with the transporter protein, bovine serum albumin (BSA) was researched utilizing multiple spectroscopic approaches combined with molecular modeling. The experimental outcomes showed that LOR entered the hydrophobic gap between the two subintervals of BSA (site II '), formed the ground-state complex with a stoichiometric ratio of 1:1, and statically quenched the endogenous fluorescence of BSA protein. During the intermolecular interaction between the two, the binding constant was with the interval of 104-106 M−1, indicating a moderate to strong affinity between the two. In addition, there was a non-radiative energy transfer from BSA to LOR, and binding with LOR diminished the α-helix content of BSA protein and affected slightly on the microenvironment surrounding the aromatic amino acids like Trp and Tyr residues. The binding of LOR to BSA was inhibited by most common metal ions, and only the Fe3+ ion promoted it. The outcomes of experiments as well as molecular dynamics simulation showed that the primary binding forces between LOR and BSA were hydrogen bonding, hydrophobic force and van der Waals force.

Unravelling transcriptional responses of the willow to Fusarium kuroshium infection

Fusarium kuroshium and the ambrosia beetle Euwallacea kuroshio attack several tree species, including the arroyo willow (Salix lasiolepis). Despite the importance of this pest, there is no molecular information about this plant-fungus interaction. Using an in vitro pathosystem of S. lasiolepis leaves – F. kurosihum and the RNA-seq approach, this study analyzed for the first time the transcriptome of both organisms at 4-, 8-, and 12-days post-inoculation. De novo assembly was done to generate the willow transcriptome, and a total of 361,2151 unique transcripts (UniGenes) were found. 4,583 UniGenes responded to the infection, and the posterior analysis showed that it contains the molecular elements to develop both pattern- and effector-triggered immunity responses (PTI and ETI, respectively). Significant expression changes of genes involved in an oxidative burst, Ca2+ signaling, and mutually antagonistic interaction between salicylic acid- and jasmonic acid/ethylene-dependent signaling suggest that the willow recognized the fungus and triggered downstream responses. Additionally, chromatin remodelers and non-coding RNA play a significant role in plant defense. Concerning F. kuroshium, 178 induced UniGenes that show homology with genes involved in the pathogenicity in other ascomycetes fungi plus transport proteins, ribosomal proteins, and uncharacterized proteins with specific domains were identified. Collectively these data provide a basis for future research on the molecular response of this transcendental tree during biotic stress, specifically during Fusarium dieback disease.

LINC01503 promotes the cell proliferation, migration and invasion of triple-negative breast cancer as a ceRNA to elevate SPNS2 expression by sponging miR-335-5p

ObjectiveTriple-negative breast cancer (TNBC) is a common cancer with high aggressiveness and high mortality in women. Recently, a plenty of studies have indicated that long non-coding RNAs (lncRNAs) exert the crucial function in human cancers, TNBC is included. The carcinogenicity of lncRNA long intergenic non-protein coding RNA 1503 (LINC01503) has been confirmed in several cancers, nevertheless, its function in TNBC still unclear. Therefore, our study aimed to reveal the underlying mechanism of LINC01503 in TNBC. MethodsIn our study, RT-qPCR was performed to detect the expression of LINC01503 in TNBC cells. The proliferative, invasive, migratory and apoptotic abilities of TNBC cells were detected by functional assay such as CCK-8, clone formation, EdU staining, transwell, and flow cytometry. RIP, RNA pull down, and luciferase assay revealed interactions between LINC01503, miR-335-5p, and sphingolipid transporter protein 2 (SPNS2). Finally, rescue experiments were performed to validate the previous results. ResultsLINC01503 expression was singularly high in TNBC cells. LINC01503 knockdown could restrain cell proliferation, invasion and migration, but accelerated cell apoptosis in TNBC. What’s more, miR-335-5p could be sponged by LINC01503 in TNBC. We also found that overexpressed miR-335-5p could inhibit cell proliferation, migration and invasion and facilitates cell apoptosis. Moreover, SPNS2 was the target gene of miR-335-5p and it functioned as an oncogene in TNBC cells. Finally, we found that overexpressed SPNS2 or inhibited miR-335-5p could reverse the suppressive function of silencing LINC01503 on TNBC progression. ConclusionLINC01503 could facilitate cell proliferation, migration and invasion of TNBC by sponging miR-335-5p to elevate SPNS2 expression.

Fasting time after feeding affects the evaluation of metabolic response in abalone Haliotis discus hannai to nutrients using dietary methionine as an example

As one of the essential amino acid, methionine (Met) is the initiating amino acid for proteins synthesis, and it can also act as a molecular signal regulating various metabolic processes. Meanwhile, the postprandial metabolic responses varied greatly among different species, nutrients and fasting time. In the present study, postprandial metabolic responses of abalone Haliotis discus hannai fed with different levels of dietary methionine (0.46%, 1.19% and 2.07%, respectively) for 84 days were investigated. Compared with the group with 0.46% of dietary methionine, 2.07% of dietary methionine significantly increased the concentration of glucose in CFH at 0 h, 12 h, 24 h, 36 h, 60 h and 84 h, while the concentrations of ammonia were significantly decreased by 2.07% of dietary methionine at each time point after feeding (P < 0.05). The 1.19% of dietary methionine significantly increased the activity of trypsin at 0 h, 24 h 60 h and 84 h after feeding (P < 0.05). The phosphorylation levels of protein kinase B (AKT), mechanistic target of rapamycin (mTOR) and ribosomal s6 protein (S6) peaked at 12 h and then dropped to base level at 36–84 h. Compared with the group with 0.46% of dietary methionine, 1.19% of dietary methionine significantly increased the phosphorylation levels of AKT at 12 h and 24 h, and extended the phosphorylation time of AKT (P < 0.05). And the phosphorylation level of mTOR was significantly increased by 1.19% of dietary methionine at 12 h, 24 h and 36 h after feeding (P < 0.05). Significant activation or repression of the mRNA levels related to glucose and lipid metabolism were observed at 12–24 h after feeding, and most of which were remain stable at 36–84 h (P < 0.05). The expressions of genes related of insulin signaling pathway (phosphoinositide 3-kinase and protein kinase B), glycolysis (hexokinase) and transport of lipid (fatty acid transport protein) were significantly increased by 1.19% of dietary methionine, while the key gene of gluconeogenesis (glucose-6-phosphatase) were decreased. In summary, 1.19% of dietary methionine could enhance digestive and absorptive capacity, protein synthesis, glucose metabolism and fatty acid transportation of abalone. Take long-term feeding trial with dietary methionine as an example and combine the results of data analysis, it is suggested to analyze the protein level of mTOR signaling pathway within 36 h after feeding, assess the biochemical parameters in CFH and the mRNA levels of nutrient metabolism related genes within 36–84 h, and detect the activities of digestive and absorptive enzymes within 60–84 h.

Studies on pharmacokinetic properties and intestinal absorption mechanism of sanguinarine chloride: in vivo and in situ

Sanguinarine (SAN) is an alkaloid with multiple biological activities, mainly extracted from Sanguinaria canadensis or Macleaya cordata. The low bioavailability of SAN limits its utilization. At present, the nature and mechanism of SAN intestinal absorption are still unclear. The pharmacokinetics, single-pass intestinal perfusion test (SPIP), and equilibrium solubility test of SAN in rats were studied. The absorption of SAN at 20, 40, and 80 mg/L in different intestinal segments was investigated, and verapamil hydrochloride (P-gp inhibitor), celecoxib (MPR2 inhibitor), and ko143 (BCRP inhibitor) were further used to determine the effect of efflux transporter proteins on SAN absorption. The equilibrium solubility of SAN in three buffer solutions (pH 1.2, 4.5 and 6.8) was investigated. The oral pharmacokinetic results in rats showed that SAN was rapidly absorbed (Tmax=0.5 h), widely distributed (Vz/F = 134 L/kg), rapidly metabolized (CL = 30 L/h/kg), and had bimodal phenomena. SPIP experiments showed that P-gp protein could significantly affect the effective permeability coefficient (Peff) and apparent absorption rate constant (Ka) of SAN. Equilibrium solubility test results show that SAN has the best solubility at pH 4.5. In conclusion, SAN is a substrate of P-gp, and its transport modes include efflux protein transport, passive transport and active transport.

Integration of highly sensitive large-area graphene-based biosensors in an automated sensing platform

Graphene-based biosensors, featuring exceptional electronic, mechanical, and surface properties, have emerged as frontrunners in advanced sensing technologies. However, to achieve widespread industrial adoption, advancements in the fabrication and integration of large-area graphene devices are essential. Critical parameters such as enhanced sensitivity, scalable production methods, economic viability, integration capabilities, and consistent uniformity must be meticulously addressed. In this work, we demonstrate that our ultra-clean, chemical wet transfer protocol of large-area graphene enables a scalable, smooth integration of graphene into an established assay platform for transporter protein drug discovery. Furthermore, we demonstrate sensitive detection of electrolytic buffers, varying pH, bovine serum albumin (BSA) and single-stranded DNA (ssDNA) adsorption, using our large-area graphene solution-gated field-effect transistor (SGFET) sensors, thereby proving their robust and reliable performance. The sensors’ biocompatibility and ion sensitivity, down to the picomolar range, substantiate their suitability for the investigation of electroactive transport in ion channels and membrane transporters.

Genome-wide analysis of Citrus medica ABC transporters reveals the regulation of fruit development by CmABCB19 and CmABCC10

ATP-binding cassette (ABC) transporters are vital for plant growth and development as they facilitate the transport of essential molecules. Despite the family's significance, limited information exists about its functional distinctions in Citrus medica. Our study identified 119 genes encoding ABC transporter proteins in the C. medica genome. Through an evolutionary tree and qPCR analysis, two ABC genes, CmABCB19 and CmABCC10, were implicated in C. medica fruit development, showing upregulation in normal fruits compared to malformed fruits. CmABCB19 was found to localize to the plasma membrane of Nicotiana tabacum, exhibiting indole-3-acetic acid (IAA) efflux activity in the yeast mutant strain yap1. CmABCC10, a tonoplast-localized transporter, exhibited efflux of diosmin, nobiletin, and naringin, with rutin influx in strain ycf1. Transgenic expression of CmABCB19 and CmABCC10 in Arabidopsis thaliana induced alterations in auxin and flavonoid content, impacting silique and seed size. This effect was attributed to the modulation of structural genes in the auxin biosynthesis (YUC5/9, CYP79B2, CYP83B1, SUR1) and flavonoid biosynthesis (4CL2/3, CHS, CHI, FLS1/3) pathways. In summary, the functional characterization of CmABCB19 and CmABCC10 illuminates auxin and flavonoid transport, offering insights into their interplay with biosynthetic pathways and providing a foundation for understanding the transporter's role in fruit development.

Pan-Cancer Analysis Reveals copper transporters as Promising Potential Targets

BackgroundCopper transport proteins (SLC31A1, ATP7A, ATP7B) regulate copper levels in the body and may be involved in tumor development. However, their comprehensive expression and function across various cancers remain unclear. MethodsCopper transporter expressions in 33 tumors and normal tissues were analyzed using TCGA, GTEx, CCLE, ULCAN, and HPA databases. Cox regression assessed their impact on patient survival. Gene alterations were explored using cBioPortal. Spearman correlation tests were performed to investigate the associations between copper transporters and tumor mutation burden (TMB), microsatellite instability (MSI), and infiltration of immune cells. Gene functions were analyzed using STRING and GeneMANIA databases. Drug sensitivity was assessed using GSCALite database. ATP7B expression in lung squamous cell carcinoma (LUSC) was validated by immunohistochemical staining. ResultsCopper transporters exhibited variable expression patterns across various cancer types, indicating their potential dual role as either oncogenes or tumor suppressor genes, depending on the cancer type. Significant associations were found between these transporters and tumor stage, as well as prognosis in most tumors studied. Pathway analysis identified links between copper transporters and tumor-related pathways like apoptosis and RAS/MAPK. Copy number variation (CNV) analysis revealed varying degrees of gene amplification and deletion of copper transporters in most tumors. Copper transporters exhibited strong correlations with immune features, including tumor mutational burden (TMB), microsatellite instability (MSI), and immune-infiltrating cells, suggesting their potential role in guiding immunotherapy. They were also associated with sensitivity to various chemotherapeutic and immunotherapeutic drugs. Immunohistochemical tests validated the correlation between elevated ATP7B level and progression-free survival (PFS) in LUSC. ConclusionCopper transporters may serve as potential tumor markers and therapeutic targets.

Direct detection of the chloride release and uptake reactions of Natronomonas pharaonis halorhodopsin

Membrane transport proteins undergo multistep conformational changes to fulfill the transport of substrates across biological membranes. Substrate release and uptake are the most important events of these multistep reactions that accompany significant conformational changes. Thus, their relevant structural intermediates should be identified to better understand the molecular mechanism. However, their identifications have not been achieved for most transporters due to the difficulty of detecting the intermediates. Herein, we report the success of these identifications for a light-driven chloride transporter halorhodopsin (HR). We compared the time course of two flash-induced signals during a single transport cycle. One is a potential change of Cl--selective membrane, which enabled us to detect tiny Cl--concentration changes due to the Cl- release and the subsequent Cl--uptake reactions by HR. The other is the absorbance change of HR reflecting the sequential formations and decays of structural intermediates. Their comparison revealed not only the intermediates associated with the key reactions but also the presences of two additional Cl--binding sites on the Cl--transport pathways. The subsequent mutation studies identified one of the sites locating the protein surface on the releasing side. Thus, this determination also clarified the Cl--transport pathway from the initial binding site until the release to the medium.

Effects of cholesterol and soy lecithin interaction on growth performance, physiology and biochemistry, and serum metabolomics of Cyprinus carpio var

This study investigated the effects of adding various concentrations of cholesterol and soy lecithin to feed on the growth performance, physiology, biochemistry, and serum metabolomics of Cyprinus carpio var. Two cholesterol concentrations (1 % and 2 %) and four soy lecithin concentrations (0 %, 2 %, 4 %, and 6 %) were employed, resulting in eight experimental groups (C1S0, C1S2, C1S4, C1S6, C2S0, C2S2, C2S4, and C2S6) that were cultivated for 60 days. The addition of C2S2 to the feeds enhanced the growth (WGR and SGR), antioxidant capacity (CAT, SOD, MDA, T-AOC, and GSH-Px), and lipid metabolism (TG, LDL-C, HDL-C, LPL, and HL) in C. carpio var. A significant interaction (P < 0.05) was observed between cholesterol and soy lecithin concentrations for WGR, SGR, and FCR, and a highly significant interaction (P < 0.01) was observed for CAT, SOD, T-AOC, GSH-Px, TG, LDL-C, and HDL-C in C. carpio var. Based on these results, three comparisons (C1S4-vs-C1S0, C2S2-vs-C2S0, and C2S2-vs-C1S2) were selected to analyze the serum metabolic profiles of C. carpio var. through LC-MS. The differential metabolites screened included amino acids and their metabolites, nucleotides and their metabolites, bile acids, fatty acids, carbohydrates and their metabolites. The metabolic pathways involved were purine metabolism, glycine, serine, and threonine metabolism, arginine and proline metabolism, and ABC transporter proteins. In summary, the interaction between cholesterol and soy lecithin significantly influenced the growth performance, antioxidant capacity, and cholesterol metabolism of C. carpio var. The most beneficial effects on growth and lipid metabolism were observed when both cholesterol and soy lecithin were added at a concentration of 2 %. The present study provides theoretical guidance for the appropriate concentrations of cholesterol and lecithin in aquafeeds.

Imaging macular carotenoids and their related proteins in the human retina with confocal resonance Raman and fluorescence microscopy

Lutein and zeaxanthin are highly concentrated at the central region of the human retina, forming a distinct yellow spot known as the macula lutea. The delivery and retention of the macular pigment carotenoids in the macula lutea involves many proteins, but their exact roles remain incompletely understood. In our study, we examined the distribution of the twelve known macular carotenoid-related proteins within the human macula and the underlying retinal pigment epithelium (RPE) using both fluorescence and Raman modes on our confocal resonance Raman microscope. Additionally, we assessed protein and gene expression through Western blot analysis and a single-cell RNA sequencing database. Our findings revealed that GSTP1, BCO2, and Aster-B exhibited distribution patterns similar to the macular carotenoids, with higher expression levels within the macular region compared to the periphery, while SR-BI and ABCA1 did not exhibit specific distribution patterns within the macula or RPE. Interestingly, LIPC, SR-BI's partner, accumulated specifically in the sub-foveal RPE. All three of these carotenoid transport proteins were found to be highly expressed in the RPE. These results offer valuable insights into the roles these proteins play in the formation of the macula lutea.

Spectroscopic and computational study of molecular interaction of Pexidartinib with homologous mammalian transport proteins

Spectroscopic and computational study of molecular interaction of Pexidartinib with homologous mammalian transport proteins

Daily exposure to chlordecone, an organochlorine pesticide, increases cardiac fibrosis and atrial fibrillation vulnerability

ContextChlordecone (CLD) is a carcinogenic organochlorine pesticide. CLD was shown to disturb the activity of cardiac Na+-K+-ATPase and Ca2+-Mg2+-ATPase. Conditions affecting these transmembrane pumps are often associated with cardiac arrhythmias (CA). However, little is known about the role of CLD on atrial fibrillation (AF) incidence, the most common type of CA. Hypotheses1) Daily ingestion of CLD induces arrhythmogenic cardiac remodeling. 2) A phase of CLD withdrawal can reduce CLD-induced AF susceptibility. MethodsAdult male Wistar rats (250 g-275 g) ingested daily-doses of CLD (0 μg/L, 0.1 μg/L, or 1 μg/L) diluted in their quotidian water for 4 weeks. From day (D)29 to D56, all rats received CLD-free water. Vulnerability to AF and cardiac function were evaluated at D28 and D56 by electrophysiological study, echocardiography, and optical-mapping. Levels of genes and proteins related to inflammation, fibrosis, and senescence were quantified by qPCR and immunoassays. ResultsTwenty-eight days of CLD exposure were associated with significantly increased AF vulnerability compared to CLD-free rats. Contamination with 1 μg/L CLD significantly reduced atrial conduction velocity (ERP, APD). CLD-weaning normalized food consumption and weight intake. However, after the CLD-withdrawal period of 28 days, AF inducibility, atrial inflammation (IL6, IL1β), and atrial fibrosis (Masson’s trichrome staining) remained significantly higher in rats exposed to 1 μg/L CLD compared to 0 μg/L. ConclusionsProlonged CLD ingestion provokes atrial conduction slowing and increased risk of AF. Although CLD-weaning, some persistent damages occurred in the atrium like atrial fibrosis and atrial senescence signals, which are accompanied by atrial inflammation and arrhythmogenicity.

The role of membrane transport proteins in 5-ALA-induced accumulation of protoporphyrin iX in tumor cells

Features of the expression of membrane importers of 5-ALA, as well as transporters involved in the removal of photoactive precursors of protoporphyrin IX (PPIX) (uro-, copro- and protoporphyrinogens), may cause differences in the effectiveness of photodynamic therapy of malignant neoplasms using 5-aminolevulinic acid (5-ALA). Increased expression of ALA transporters is associated with an increase in the intensity of PPIX synthesis. When the expression of PPIX exporters increases, there is a decrease in PPIX concentration. The review describes the main transporters of 5-ALA, uro-, copro- and protoporphyrinogens, provides data on their expression in various tissues, and discusses the possibility of predicting the effectiveness of photodynamic therapy considering the expression of the corresponding transport proteins in malignant tissues.

Static magnetic field-modulated mesenchymal stem cell-derived mitochondria-containing microvesicles for enhanced intervertebral disc degeneration therapy

Intervertebral disc degeneration (IVDD) is characterized by the senescence and declining vitality of nucleus pulposus cells (NPCs), often driven by mitochondrial dysfunction. This study elucidates that mesenchymal stem cells (MSCs) play a crucial role in attenuating NPC senescence by secreting mitochondria-containing microvesicles (mitoMVs). Moreover, it demonstrates that static magnetic fields (SMF) enhance the secretion of mitoMVs by MSCs. By distinguishing mitoMV generation from exosomes, this study shifts focus to understanding the molecular mechanisms of SMF intervention, emphasizing cargo transport and plasma membrane budding processes, with RNA sequencing indicating the potential involvement of the microtubule-based transport protein Kif5b. The study further confirms the interaction between Rab22a and Kif5b, revealing Rab22a’s role in sorting mitoMVs into microvesicles (MVs) and potentially mediating subsequent plasma membrane budding. Subsequent construction of a gelatin methacrylate (GelMA) hydrogel delivery system further addresses the challenges of in vivo application and verifies the substantial potential of mitoMVs in delaying IVDD. This research not only sheds light on the molecular intricacies of SMF-enhanced mitoMV secretion but also provides innovative perspectives for future IVDD therapeutic strategies.