Search

Intracellular trafficking, an extremely complex network, dynamically orchestrates nearly all cellular activities. A versatile method that enables the manipulation of target transport pathways with high spatiotemporal accuracy in vitro and in vivo is required to study how this network coordinates its functions. Here, a new method called RIVET (Rapid Immobilization of target Vesicles on Engaged Tracks) is presented. Utilizing inducible dimerization between target vesicles and selective cytoskeletons, RIVET can spatiotemporally halt numerous intracellular trafficking pathways within seconds in a reversible manner. Its highly specific perturbations allow for the real‐time dissection of the dynamic relationships among different trafficking pathways. Moreover, RIVET is capable of inhibiting receptor‐mediated endocytosis. This versatile system can be applied from the cellular level to whole organisms. RIVET opens up new avenues for studying intracellular trafficking under various physiological and pathological conditions and offers potential strategies for treating trafficking‐related disorders. [ABSTRACT FROM AUTHOR]

Background: Familial hypercholesterolemia (FH) is an autosomal dominant disorder characterized by increased LDL-cholesterol levels. About 85% of FH cases are caused by LDLR mutations encoding the low-density lipoprotein receptor (LDLR). LDLR is synthesized in the endoplasmic reticulum (ER) where it undergoes post-translational modifications and then transported through Golgi apparatus to the plasma membrane. Over 2900 LDLR variants have been reported in FH patients with limited information on the pathogenicity and functionality of many of them. This study aims to elucidate the cellular trafficking and functional implications of LDLR missense variants identified in suspected FH patients using biochemical and functional methods. Methods: We used HeLa, HEK293T, and LDLR-deficient-CHO-ldlA7 cells to evaluate the subcellular localization and LDL internalization of ten LDLR missense variants (p.C167F, p.D178N, p.C243Y, p.E277K, p.G314R, p.H327Y, p.D477N, p.D622G, p.R744Q, and p.R814Q) reported in multiethnic suspected FH patients. We also analyzed the functional impact of three variants (p.D445E, p.D482H, and p.C677F), two of which previously shown to be retained in the ER. Results: We show that p.D622G, p.D482H, and p.C667F are largely retained in the ER whereas p.R744Q is partially retained. The other variants were predominantly localized to the plasma membrane. LDL internalization assays in CHO-ldlA7 cells indicate that p.D482H, p.C243Y, p.D622G, and p.C667F have quantitatively lost their ability to internalize Dil-LDL with the others (p.C167F, p.D178N, p.G314R, p.H327Y, p.D445E, p.D477N, p.R744Q and p.R814Q) showing significant losses except for p.E277K which retained full activity. However, the LDL internalization assay is only to able evaluate the impact of the variants on LDL internalization and not the exact functional defects such as failure to bind LDL. The data represented illustrate the hypomorphism nature of variants causing FH which may explain some of the variable expressivity of FH. Conclusion: Our combinatorial approach of in silico, cellular, and functional analysis is a powerful strategy to determine pathogenicity and FH disease mechanisms which may provide opportunitites for novel therapeutic strategies. [ABSTRACT FROM AUTHOR]

BackgroundFamilial hypercholesterolemia (FH) is an autosomal dominant disorder characterized by increased LDL-cholesterol levels. About 85% of FH cases are caused by LDLR mutations encoding the low-density lipoprotein receptor (LDLR). LDLR is synthesized in the endoplasmic reticulum (ER) where it undergoes post-translational modifications and then transported through Golgi apparatus to the plasma membrane. Over 2900 LDLR variants have been reported in FH patients with limited information on the pathogenicity and functionality of many of them. This study aims to elucidate the cellular trafficking and functional implications of LDLR missense variants identified in suspected FH patients using biochemical and functional methods.MethodsWe used HeLa, HEK293T, and LDLR-deficient-CHO-ldlA7 cells to evaluate the subcellular localization and LDL internalization of ten LDLR missense variants (p.C167F, p.D178N, p.C243Y, p.E277K, p.G314R, p.H327Y, p.D477N, p.D622G, p.R744Q, and p.R814Q) reported in multiethnic suspected FH patients. We also analyzed the functional impact of three variants (p.D445E, p.D482H, and p.C677F), two of which previously shown to be retained in the ER.ResultsWe show that p.D622G, p.D482H, and p.C667F are largely retained in the ER whereas p.R744Q is partially retained. The other variants were predominantly localized to the plasma membrane. LDL internalization assays in CHO-ldlA7 cells indicate that p.D482H, p.C243Y, p.D622G, and p.C667F have quantitatively lost their ability to internalize Dil-LDL with the others (p.C167F, p.D178N, p.G314R, p.H327Y, p.D445E, p.D477N, p.R744Q and p.R814Q) showing significant losses except for p.E277K which retained full activity. However, the LDL internalization assay is only to able evaluate the impact of the variants on LDL internalization and not the exact functional defects such as failure to bind LDL. The data represented illustrate the hypomorphism nature of variants causing FH which may explain some of the variable expressivity of FH.ConclusionOur combinatorial approach of in silico, cellular, and functional analysis is a powerful strategy to determine pathogenicity and FH disease mechanisms which may provide opportunitites for novel therapeutic strategies.

Extracellular vesicles (EVs) have recently received much attention about the application of drug carriers due to their desirable properties such as nano-size, biocompatibility, and high stability. Herein, we demonstrate orange-derived extracellular vesicles (OEV) nanodrugs (DN@OEV) by modifying cRGD-targeted doxorubicin (DOX) nanoparticles (DN) onto the surface of OEV, enabling significantly enhancing tumor accumulation and penetration, thereby efficiently inhibiting the growth of ovarian cancer. The obtained DN@OEV enabled to inducement of greater transcytosis capability in ovarian cancer cells, which presented the average above 10-fold transcytosis effect compared with individual DN. It was found that DN@OEV could trigger receptor-mediated endocytosis to promote early endosome/recycling endosomes pathway for exocytosis and simultaneously reduce degradation in the early endosomes-late endosomes-lysosome pathway, thereby inducing the enhanced transcytosis. In particular, the zombie mouse model bearing orthotopic ovarian cancer further validated DN@OEV presented high accumulation and penetration in tumor tissue by the transcytosis process. Our study indicated the strategy in enhancing transcytosis has significant implications for improving the therapeutic efficacy of the drug delivery system.

Dent disease type 1 is characterized by pathogenic CLCN5 gene variants and impaired receptor-mediated endocytosis in proximal tubules. However, mutation-related abnormalities in proximal tubules have not yet been described. Here, we present three patients with CLCN5 alterations and distinct morphological changes of the apical endocytic-lysosomal apparatus. The proximal tubular ultrastructure was investigated in kidney biopsy samples of three boys genotyped for non-nephrotic proteinuria. Controls: seven patients with nephrotic-range glomerular proteinuria. The genotyping findings revealed an already-known missense mutation in one patient and hitherto undescribed frameshift variants in two patients. Low-molecular-weight proteinuria, focal global glomerulosclerosis, proximal tubular changes, and tubular calcium deposits characterized each case. Three subsets of proximal tubular cells were observed: those without any abnormality, those with aplasia of apical endocytic-lysosomal apparatus and shrinkage of cells, and those with hypoplasia of apical endocytic apparatus, accumulation of proteinaceous substance in dysmorphic lysosomes, and dysmorphic mitochondria. The distribution of subsets varied from patient to patient. In one patient with a frameshift variant, an oxidative stress-like injury of proximal tubular cells and podocytes accompanied the above-mentioned alterations. Focal aplasia/hypoplasia of apical endocytic apparatus and subsequent changes in cytoplasmic organelles characterized proximal tubules in the CLCN5 pathogenic variants. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) have recently received much attention about the application of drug carriers due to their desirable properties such as nano-size, biocompatibility, and high stability. Herein, we demonstrate orange-derived extracellular vesicles (OEV) nanodrugs (DN@OEV) by modifying cRGD-targeted doxorubicin (DOX) nanoparticles (DN) onto the surface of OEV, enabling significantly enhancing tumor accumulation and penetration, thereby efficiently inhibiting the growth of ovarian cancer. The obtained DN@OEV enabled to inducement of greater transcytosis capability in ovarian cancer cells, which presented the average above 10-fold transcytosis effect compared with individual DN. It was found that DN@OEV could trigger receptor-mediated endocytosis to promote early endosome/recycling endosomes pathway for exocytosis and simultaneously reduce degradation in the early endosomes-late endosomes-lysosome pathway, thereby inducing the enhanced transcytosis. In particular, the zombie mouse model bearing orthotopic ovarian cancer further validated DN@OEV presented high accumulation and penetration in tumor tissue by the transcytosis process. Our study indicated the strategy in enhancing transcytosis has significant implications for improving the therapeutic efficacy of the drug delivery system. The enhanced transcytosis of cell-DN@OEV interaction was involved in receptor-mediated endocytosis, intracellular trafficking, and exocytosis. The enhanced transcytosis of extracellular vesicles-based drug delivery system would achieve to improve delivery efficiency by targeting modification. [Display omitted] [ABSTRACT FROM AUTHOR]

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters cells by binding to the angiotensin-converting enzyme 2 (hACE2) receptor. This process is aided by the transmembrane protease serine 2 (TMPRSS2), which enhances entry efficiency and infectiousness by cleaving the SARS-CoV-2 surface glycoprotein (Spike). The cleavage primes the Spike protein, promoting membrane fusion instead of receptor-mediated endocytosis. Despite the pivotal role played by TMPRSS2, our understanding of its non-protease distinct domains remains limited. In this report, we present evidence indicating the potential phosphorylation of a minimum of six tyrosine residues within the cytosolic tail (CT) of TMPRSS2. Via the use of TMPRSS2 CT phospho-mimetic mutants, we observed a reduction in TMPRSS2 protease activity, accompanied by a decrease in SARS-CoV-2 pseudovirus transduction, which was found to occur mainly via the endosomal pathway. We expanded our investigation beyond TMPRSS2 CT and discovered the involvement of other non-protease domains in regulating infection. Our co-immunoprecipitation experiments demonstrated a strong interaction between TMPRSS2 and Spike. We revealed a 21 amino acid long TMPRSS2-Spike-binding region (TSBR) within the TMPRSS2 scavenger receptor cysteine-rich (SRCR) domain that contributes to this interaction. Our study sheds light on novel functionalities associated with TMPRSS2's cytosolic tail and SRCR region. Both of these regions have the capability to regulate SARS-CoV-2 entry pathways. These findings contribute to a deeper understanding of the complex interplay between viral entry and host factors, opening new avenues for potential therapeutic interventions. [ABSTRACT FROM AUTHOR]

Abstract The non-specificity of standard anticancer therapies has profound detrimental consequences in clinical treatment. Therapeutic specificity can be precisely achieved using cutting-edge ligands. Small synthetic oligonucleotide-ligands chosen through Systematic evolution of ligands by exponential enrichment (SELEX) would be an unceasing innovation in using nucleic acids as aptamers, frequently referred to as "chemical antibodies.” Aptamers act as externally controlled switching materials that can attach to various substrates, for example, membrane proteins or nucleic acid structures. Aptamers pose excellent specificity and affinity for target molecules and can be used as medicines to suppress tumor cell growth directly. The creation of aptamer-conjugated nanoconstructs has recently opened up innovative options in cancer therapy that are more effective and target tumor cells with minor toxicity to healthy tissues. This review focuses on a comprehensive description of the most capable classes of aptamer-tethered nanocarriers for precise recognition of cancer cells with significant development in proficiency, selectivity, and targetability for cancer therapy. Existing theranostic applications with the problems and future directions are also highlighted. Graphical Abstract

Effective chemotherapy for clinical treatment of brain diseases is still lacking due to the poor penetration of the blood-brain barrier (BBB). The aim of this study was to construct a folate modified pterostilbene (Pt) loaded polymeric micellar delivery system (F-Pt/M) with mPEG-PCL as carrier material to aim at penetrating the BBB for brain tissue targeting via receptor-mediated endocytosis. In this study, F-Pt/M was prepared using thin-film hydration method and then optimized by response surface methodology (RSM) with the entrapment efficiency (EE), drug loading (DL) and hydrodynamic diameter (HD) as indexes. The average hydrodynamic diameter and zeta potential of optimal F-Pt/M were 133.2 nm and 24.6 mV, respectively. DL (18.3%) and EE (98.6%) made the solubility of Pt in water about 25 times higher than that of crude Pt. Results of DSC evaluation revealed that drugs were successfully encapsulated inside the polymeric micelles. TEM images showed that homogeneous spherical micellar structures with a narrow size distribution were developed. The release result in vitro showed that F-Pt/M presented sustained release behavior compared to control free Pt solution. Compared to non-targeted Pt/M, F-Pt/M had a significantly higher cytotoxicity against FR-overexpressing A172 cells. In vitro cellular uptake tests illustrated that the micellar delivery system could significantly improve the accumulation of drugs in target cells via receptor-mediated endocytosis. BBB penetration value (P) of F-Pt/M was about 4 folds higher than that of free Pt group. In addition, drug targeting index (DTI) was calculated to determine targeting of F-Pt/M to the brain which was found to be 4.89, implying improved brain targeting was achieved. Hence, the developed F-Pt/M exhibited great potential for delivering more drug molecules across the BBB for the treatment of brain diseases.

Electric and electromagnetic pulses have been shown to enhance the endocytosis rate, with all-or-nothing responses beyond a field strength threshold and linear responses as a function of field strength and treatment duration utilizing bipolar symmetrical and monopolar pulses, respectively. Malignant glioma (MG) is resistant to chemotherapy. The present study looked for a new electrical impulse that can aid electrochemotherapy to deliver anticancer drugs while using less electrical energy. Bipolar asymmetric electric pulses were applied to U251MG cells suspended in physiologically conductive media in the presence of molecular probes, including Bleomycin. The delivered electric pulses with a pulse duration range of 180-500 µs and a frequency range of 100-400 Hz had a low field intensity ranging from 1.5 V/cm to 7.3 V/cm. Spectrophotometric and spectrofluorometric measurements were used to investigate the impact of these variables on cancer cell survival and the molecular probe uptake induced by the electric pulses. An all-or-nothing response was observed above a specified threshold of electric field intensity of 4 V/cm. This threshold was unaffected by changes in repetition frequency or pulse duration. It was not a temperature effect that caused the molecular probe uptake to increase. When bipolar asymmetric electric pulses were applied just before electroporation, the effectiveness of the cytotoxic impact of bleomycin was increased from 80%, when employing electroporation pulses alone, to 100%.

Peptide–drug conjugates are delivery systems for selective delivery of cytotoxic agents to target cancer cells. In this work, the optimized synthesis of JH-VII-139-1 and its c(RGDyK) peptide conjugates is presented. The low nanomolar SRPK1 inhibitor, JH-VII-139-1, which is an analogue of Alectinib, was linked to the ανβ3 targeting oligopeptide c(RGDyK) through amide, carbamate and urea linkers. The chemostability, cytotoxic and antiangiogenic properties of the synthesized hybrids were thoroughly studied. All conjugates retained mid nanomolar-level inhibitory activity against SRPK1 kinase and two out of four conjugates, geo75 and geo77 exhibited antiproliferative effects with low micromolar IC50 values against HeLa, K562, MDA-MB231 and MCF7 cancer cells. The activities were strongly related to the stability of the linkers and the release of JH-VII-139-1. In vivo zebrafish screening assays demonstrated the ability of the synthesized conjugates to inhibit the length or width of intersegmental vessels (ISVs). Flow cytometry experiments were used to test the cellular uptake of a fluorescein tagged hybrid in MCF7 and MDA-MB231 cells that revealed a receptor-mediated endocytosis process. In conclusion, most conjugates retained the inhibitory potency against SRPK1 as JH-VII-139-1 and demonstrated antiproliferative and antiangiogenic activities. Further animal model experiments are needed to uncover the full potential of such peptide conjugates in cancer therapy and angiogenesis-related diseases. [ABSTRACT FROM AUTHOR]

Innumerable people worldwide die of cancer every year, although pharmaceutical therapy has actualized many benefits in human health. For background, anti-cancer drug development is difficult due to the multifactorial pathogenesis and complicated pathology of cancers. Cancer cells excrete hydrophobic low-molecular anti-cancer drugs by overexpressed efflux transporters such as multiple drug resistance 1 (MDR1) at the apical membrane. Mutation-driven drug resistance is also developed in cancer. Moreover, the poor distribution of drug to cancer cells is a serious problem, because patients suffer from off-target side effects. Thus, highly selective and effective drug delivery into solid cancer cells across the membrane should be established. It is known that substances (10–100 nm in diameter) such as monoclonal antibodies (mAbs) (approximately 14.2 nm in diameter) or nanoparticles spontaneously gather in solid tumor stroma or parenchyma through the capillary endothelial fenestration, ranging from 200–2000 nm, in neovasculatures due to the enhanced permeability and retention (EPR) effect. Furthermore, cancer antigens, such as HER2, Nectin-4, or TROP2, highly selectively expressed on the surface of cancer cells act as a receptor for receptor-mediated endocytosis (RME) using mAbs against such antigens. Thus, antibody–drug conjugates (ADCs) are promising anti-cancer pharmaceutical agents that fulfill accurate distribution due to the EPR effect and due to antibody–antigen binding and membrane permeability owing to RME. In this review, I introduce the implementation and possibility of highly selective anti-cancer drug delivery into solid cancer cells based on the EPR effect and RME using anti-cancer antigens ADCs with payloads through suitable linkers. [ABSTRACT FROM AUTHOR]

Megalin and cubilin, endocytic proteins present in the proximal tubule of the kidney, are responsible for reabsorbing filtered proteins from urine. Our hypothesis was that potential substrates of megalin/cubilin could be identified by examining urinary protein differences between control (WT) mice and kidney-specific megalin knockdown (KD) mice. Using the IonStar proteomics approach, 877 potential megalin/cubilin substrates were discovered, with 23 of these compounds representing known megalin/cubilin substrates. Some of the proteins with the largest fold changes in the urine between KD and WT included the known megalin substrates retinol-binding protein and vitamin D-binding protein. Of the total proteins identified as novel substrates, about three-quarters of compounds had molecular weights (MWs) below 69 kDa, the MW of albumin, and the remaining had higher MWs, with about 5% of the proteins having MWs greater than 150 kDa. Sex differences in the number of identified substrates occurred, but this may be due to differences in kidney megalin expression between both male and female megalin KD and WT animals, with the ratio of megalin between WT and KD being 2.76 and 2.14 for female and male mice, respectively. The top three ingenuity canonical pathways based on the urinary proteins in both female and male KD mice were acute phase response signaling, liver X receptor/retinoid X receptor activation, and intrinsic prothrombin activation pathways. In conclusion, analysis of urine samples from kidney-specific megalin KD and WT mice was found to be useful for the identification of potential endogenous substrates for megalin and cubilin. [ABSTRACT FROM AUTHOR]

Efficient conventional chemotherapy is limited by its nonspecific nature, which causes severe systemic toxicity that can lead to patient discomfort and low therapeutic efficacy. The emergence of smart drug delivery systems (SDDSs) utilizing nanoparticles as drug nanocarriers has shown great potential in enhancing the targetability of anticancer agents and limiting their side effects. Liposomes are among the most investigated nanoplatforms due to their promising capabilities of encapsulating hydrophilic, lipophilic, and amphiphilic drugs, biocompatibility, physicochemical and biophysical properties. Liposomal nanodrug systems have demonstrated the ability to alter drugs' biodistribution by sufficiently delivering the entrapped chemotherapeutics at the targeted diseased sites, sparing normal cells from undesired cytotoxic effects. Combining liposomal treatments with ultrasound, as an external drug release triggering modality, has been proven effective in spatially and temporally controlling and stimulating drug release. Therefore, this paper reviews recent literature pertaining to the therapeutic synergy of triggering nanodrugs from liposomes using ultrasound. It also highlights the effects of multiple physical and chemical factors on liposomes' sonosensetivity, several ultrasound-induced drug release mechanisms, and the efficacy of ultrasound-responsive liposomal systems in cancer therapy. Overall, liposomal nanodrug systems triggered by ultrasound are promising cancer therapy platforms that can potentially alleviate the detriments of conventional cancer treatments. [ABSTRACT FROM AUTHOR]

Abstract Magnetite (Fe3O4)-gold (Au) core-shell nanoparticles (NPs) have unique magnetic and optical properties. When combined with biological moieties, these NPs can offer new strategies for biomedical applications, such as drug delivery and cancer targeting. Here, we present an effective method for the controllable cellular uptake of magnetic core-shell NP systems combined with biological moieties. Vimentin, which is the structural protein, has been biochemically confirmed to affect phagocytosis potently. In addition, vimentin affects exogenic materials internalization into cells even though under multiple inhibitions of biological moieties. In this study, we demonstrate the cellular internalization performance of Fe3O4-Au core-shell NPs with surface modification using a combination of biological moieties. The photofluorescence of vimentin-tagged NPs remained unaffected under multiple inhibition tests, indicating that the NPs were minimally influenced by nystatin, dynasore, cytochalasin D, and even the Muc1 antibody (Ab). Consequently, this result indicates that the Muc1 Ab can target specific molecules and can control specific endocytosis. Besides, we show the possibility of controlling specific endocytosis in colorectal cancer cells.

Clathrin-mediated endocytosis (CME) is the major route through which cells internalise various substances and recycle membrane components. Via the coordinated action of many proteins, the membrane bends and invaginates to form a vesicle that buds off—along with its contents—into the cell. The contribution of the actin cytoskeleton to this highly dynamic process in mammalian cells is not well understood. Unlike in yeast, where there is a strict requirement for actin in CME, the significance of the actin cytoskeleton to mammalian CME is variable. However, a growing number of studies have established the actin cytoskeleton as a core component of mammalian CME, and our understanding of its contribution has been increasing at a rapid pace. In this review, we summarise the state-of-the-art regarding our understanding of the endocytic cytoskeleton, its physiological significance, and the questions that remain to be answered.

Receptor-mediated endocytosis has been used for tissue targeted delivery of short interfering RNA (siRNA) drugs. Herein, we investigated adenosine receptor (AR) as a candidate for receptor-mediated siRNA internalization. We synthesized adenosine functionalized cationic curdlan derivatives (denote CuAMP polymers). One of these polymers, CuAMP4, efficiently delivered siRNA to breast cancer cells expressing high level of A 2B receptor. The internalization of siRNA loaded CuAMP4 by cancer cells was inhibited by free AMP as well as endocytosis inhibitors. Moreover, knockdown of A 2B R by siRNA, or pre-treatment of the cells with anti-A 2B R antibody, strongly inhibited the cellular uptake of CuAMP4. Our findings confirmed that A 2B R can be utilized for cell type specific siRNA delivery, and CuAMP4 NP may be a promising delivery system for cancer cell targeted delivery of therapeutic siRNAs. [Display omitted] • Adenosine functionalized cationic curdlan has been successfully synthesized. • CuAMP4-based nanoparticles delivered siRNA to cell and induced RNAi. • siRNA/CuAMP4 was internalized via A 2B receptor mediated endocytosis. • A 2B receptor can be utilized for cell type specific siRNA delivery. [ABSTRACT FROM AUTHOR]

The pathogenesis of Parkinson's disease (PD), which is a progressive neurodegenerative disease, is associated with the formation of protein inclusion bodies called Lewy bodies (LB) or Lewy neurites (LN). α‐Synuclein (α‐Syn) is a major component of LB and LN. The formation of LB or LN is mediated by formation of α‐Syn fibrils, which are formed from α‐Syn monomers and oligomers. Additionally, intercellular α‐Syn propagation has been proposed to be important for the progression of PD. Thus, various studies have focused on elucidating the role of α‐Syn propagation in the pathogenesis of PD. Previous studies have reported that α‐Syn species are released from the cells through various pathways, including the unconventional secretion pathways. The released α‐Syn species are internalized by the cells through multiple mechanisms, including receptor‐mediated endocytosis. Some molecular processes involved in intercellular α‐Syn propagation have been recently elucidated. This review discusses the current studies on the molecular mechanisms underlying the release and uptake of α‐Syn and their physiological relevance. [ABSTRACT FROM AUTHOR]

Objectives. Over the last few years, medicinal chemistry research has been focusing on the creation of molecules that can target particular body systems, organs and tissues, thus abating systemic toxicity and side effects, and, most of all, boosting therapeutic potential. This goal can be achieved through the specific interaction of such drugs with active sites of cellular receptors. For example, glycoprotein receptors that can be found on cellular surfaces in neural tissues and liver parenchyma, selectively bind various glycoproteins and glycosides, facilitating their penetration into cells. This review describes how certain parameters of ligand structure (the nature and length of the spacer between carbohydrate and non-carbohydrate fragments of the molecule, number of carbohydrate residues per molecule, etc.) influence the penetration efficiency of synthetic glycoconjugates into liver cells.Methods. This review article summarizes 75 research papers and discusses data from in vitro and in vivo experiments showing which structures of synthetic carbohydrate derivatives are optimal for targeted drug delivery into liver cells.Results. The surface of liver cells (hepatocytes) contains a significant number of asialoglycoprotein receptors (ASGP-R) that are almost never found elsewhere. This makes ASGP-R an ideal target for the directed treatment of liver diseases, including such difficult, socially important conditions as hepatocellular carcinoma and Hepatitis C. A number of various ligands and targeted (to ASGP-R) delivery systems have been designed. Such molecules always contain derivatives of mono- and disaccharides, most commonly D-glucose, D-galactose, D-lactose and N-acetylglucosamines. This review contains the chemical structures of carbohydrate-based ligands.Conclusions. Glycolipids based on D-carbohydrates, when in liposomes, facilitate penetration into liver cells by a receptor-mediated, clathrin-dependent endocytosis mechanism that is activated upon contact of the carbohydrate-containing ligand fragment with the active site of ASGP-R. It can be addressed by the use of monovalent derivatives of carbohydrates as well as polyvalent glycoconjugates. Alterations in the ligand structure and the number of liposomal modifications can boost the therapeutic effect. The distance between the liposomal surface and the carbohydrate residue (spacer length), as well as the hydrophilic-lipophilic balance of the ligand molecule, have a great effect on the affinity and cellular response.

Tumor-sensitivity, effective transport, and precise delivery to tumor cells of nano drug delivery systems (NDDs) have been great challenges to cancer therapy in recent years. The conventional targeting approach involves actively installing the corresponding ligand on the nanocarriers, which is prone to recognize the antigen blasts overexpressed on the surface of tumor cells. However, there are some probable limitations for the active tumor-targeting systems in vivo as follows: a. the limited ligand amount of modifications; b. possible steric hindrance, which was likely to prevent ligand-receptor interaction during the delivery process. c. the restrained antigen saturation highly expressed on the cell membrane, will definitely decrease the specificity and often lead to "off-target" effects of NDDs; and d. water insolubility of nanocarriers due to excess of ligands modification. Obviously, any regulation of receptors on surface of tumor cells exerted an important influence on the delivery of targeting systems. Herein, receptor upregulation was mostly desired for enhancing targeted therapy from the cellular level. This technique with the amplification of receptors has the potential to enhance tumor sensitivity towards corresponding ligand-modified nanoparticles, and thereby increasing the effective therapeutic concentration as well as improving the efficacy of chemotherapy. The enhancement of positively expressed receptors on tumor cells and receptor-dependent therapeutic agents or NDDs with an assembled "self-promoting" effect contributes to increasing cell sensitivity to NPs, and will provide a basic platform for clinical therapeutic practice. In this review, we highlight the significance of modulating various receptors on different types of cancer cells for drug delivery and therapeutic benefits. [Display omitted] • Any regulation of receptor on surface of tumor cells exerted important influence on the targeting delivery systems. • The weak tumor-targeting could be overcome by increasing cancer cells sensitivity to NDDs via the amplification of surface receptors. In addition, Receptors contributing to apoptosis may also lead to tumor shrinkage via specific signaling pathway. • The significance of modulating receptors on different types of cancer cells was proposed for drug delivery. • The strategy was mostly propitious for enhancing efficacy of targeted-small molecules, anti-body or NDDs, providing platform for clinical therapeutic practice. [ABSTRACT FROM AUTHOR]

Therapeutic immunoglobulin G (IgG) antibodies comprise the largest class of protein therapeutics. Several factors that influence their overall disposition have been well-characterized, including target-mediated mechanics and convective flow. What remains poorly defined is the potential for non-targeted entry into various tissues or cell types by means of uptake via cell surface receptors at those sites. Megalin and cubilin are large endocytic receptors whose cooperative function plays important physiological roles at the tissues in which they are expressed. One such example is the kidney, where loss of either results in significant declines in proximal tubule protein reabsorption. Due to their diverse ligand profile and broad tissue expression, megalin and cubilin represent potential candidates for receptor-mediated uptake of IgG into various epithelia. Therefore, the objective of the current work was to determine if IgG was a novel ligand of megalin and/or cubilin. Direct binding was measured for human IgG with both megalin and the cubilin/amnionless complex. Additional work focusing on the megalin-IgG interaction was then conducted to build upon these findings. Cell uptake studies using megalin ligands for competitive inhibition or proximal tubule cells stably transduced with megalin-targeted shRNA constructs supported a role for megalin in the endocytosis of human IgG. Furthermore, a pharmacokinetic study using transgenic mice with a kidney-specific mosaic knockout of megalin demonstrated increased urinary excretion of human IgG in megalin knockout mice when compared to wild-type controls. These findings indicate that megalin is capable of binding and internalizing IgG via a high affinity interaction. [ABSTRACT FROM AUTHOR]

Prajakta Tambe,1,2,* Pramod Kumar,1,2,* Kishore M Paknikar,1,2 Virendra Gajbhiye1,2 1Nanobioscience Group, Agharkar Research Institute, Pune, India; 2Savitribai Phule Pune University, Pune, India *These authors contributed equally to this work Background: Considering the increase in cancer cases and number of deaths per year worldwide, development of potential therapeutics is imperative. Mesoporous silica nanoparticles (MSNPs) are among the potential nanocarriers having unique properties for drug delivery. Doxorubicin (DOX), being the most commonly used drug, can be efficiently delivered to gonadotropin-releasing hormone (GnRH)-overexpressing cancer cells using functionalized MSNPs.Aim: We report the development of decapeptide-conjugated MSNPs loaded with DOX for the targeted drug delivery in breast and prostate cancer cells.Materials and methods: MSNPs were synthesized and subsequently functionalized with an analog of GnRH by using a heterobifunctional polyethylene glycol as a linker. These targeted MSNPs were then characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. An anticancer drug DOX was loaded and then characterized for drug loading. DOX-loaded nanocarriers were then studied for their cellular uptake using confocal microscopy. The cytotoxicity of DOX-loaded targeted MSNPs and DOX-loaded bare MSNPs was studied by performing MTT assay on MCF-7 (breast cancer) and LNCaP (prostate cancer) cells. Further, acridine orange/ethidium bromide staining, as well as flow cytometry, was performed to confirm the apoptotic mode of cancer cell death.Results: MSNPs were conjugated with polyethylene glycol as well as an agonist of GnRH and subsequently loaded with DOX. These targeted and bare MSNPs showed excellent porous structure and loading of DOX. Further, higher uptake of DOX-loaded targeted MSNPs was observed as compared to DOX-loaded bare MSNPs in GnRH-overexpressing breast (MCF-7) and prostate (LNCaP) cancer cells. The targeted MSNPs also showed significantly higher (P

Key points: The presence of plasma proteins in urine is difficult to interpret quantitatively. It may be a result of impaired glomerular filtration or impaired proximal tubule (PT) reabsorption, or both.Dent1 disease (CLCN5 mutation) abolishes PT protein reabsorption leaving glomerular function intact. Using urine protein measurements from patients with Dent1 disease and normal individuals, we devised a mathematical model that incorporates two PT transport processes with distinct kinetics. This model predicts albumin, α1‐microglobulin (α1‐m), β2‐microglobulin (β2‐m) and retinol‐binding protein 4 (RBP4) urine concentrations.Our results indicate that the urinary excretion of β2‐m and RBP4 differs from that of albumin and α1‐m in their sensitivity to changes in the glomerular filtration rate, glomerular protein leak, tubular protein uptake via endocytosis and PT water reabsorption.The model predicts quantitatively how hyperfiltration and glomerular leak interact to promote albuminuria.Our model should contribute to improved understanding and interpretation of urine protein measurements in renal disease. To clarify the relative contributions of glomerular filtration and tubular uptake to urinary protein excretion, we developed a mathematical model of protein reabsorption in the human proximal tubule (PT) using Michaelis–Menten kinetics and molar urinary protein measurements taken from human Dent1 disease (CLCN5 loss‐of‐function mutation). β2‐Microglobulin (β2‐m) and retinol‐binding protein 4 (RBP4) are normally reabsorbed with 'very high' efficiency uptake kinetics and fractional urinary excretion of 0.025%, whereas albumin and α1‐microglobulin (α1‐m) are reabsorbed by 'high' efficiency uptake kinetics and 50‐fold higher fractional urinary excretion of 1.15%. Our model correctly predicts the urinary β2‐m, RBP4 and α1‐m content in aristolochic acid nephropathy, and elevated β2‐m excretion with increased single nephron glomerular filtration rate (SNGFR) following unilateral‐nephrectomy. We explored how altered endocytic uptake, water reabsorption, SNGFR and glomerular protein filtration affect excretion. Our results help to explain why β2‐m and RBP4 are more sensitive markers of PT dysfunction than albumin or α1‐m, and suggest that reduced PT sodium and water reabsorption in Fanconi syndrome may contribute to proteinuria. Transition of albumin excretion from normal to microalbuminuria, a 5‐fold increase, corresponds to a 3.5‐fold elevation in albumin glomerular filtration, supporting the use of microalbuminuria screening to detect glomerular leak in diabetes. In macroalbuminuria, small albumin permeability changes produce large changes in excretion. However, changes in SNGFR can alter protein excretion, and hyperfiltration with glomerular leak can combine to increase albuminuria. Our model provides a validated quantitative description of the transport processes underlying the protein composition of human urine in normal and pathophysiological states. Key points: The presence of plasma proteins in urine is difficult to interpret quantitatively. It may be a result of impaired glomerular filtration or impaired proximal tubule (PT) reabsorption, or both.Dent1 disease (CLCN5 mutation) abolishes PT protein reabsorption leaving glomerular function intact. Using urine protein measurements from patients with Dent1 disease and normal individuals, we devised a mathematical model that incorporates two PT transport processes with distinct kinetics. This model predicts albumin, α1‐microglobulin (α1‐m), β2‐microglobulin (β2‐m) and retinol‐binding protein 4 (RBP4) urine concentrations.Our results indicate that the urinary excretion of β2‐m and RBP4 differs from that of albumin and α1‐m in their sensitivity to changes in the glomerular filtration rate, glomerular protein leak, tubular protein uptake via endocytosis and PT water reabsorption.The model predicts quantitatively how hyperfiltration and glomerular leak interact to promote albuminuria.Our model should contribute to improved understanding and interpretation of urine protein measurements in renal disease. [ABSTRACT FROM AUTHOR]

Background and Aim: Mitochondrial damage is commonly involved in liver injury. We have previously shown that normal mitochondria can be coated with a carrier protein to form complexes that are specifically taken up by liver cells in culture. The aim of the current study was to determine whether mitochondrial complexes could be specifically delivered to the livers of living rats by intravenous injection. Methods: Mitochondria were harvested from fresh mouse liver, mixed with an asialoglycoprotein‐based carrier, asialoorosomucoid‐polylysine (AsOR‐PL), and purified to form complexes. To facilitate the release of internalized mitochondria from endosomes, an endosomolytic peptide, listeriolysin O (LLO), was coupled to AsOR to form AsOR‐LLO. Mitochondria alone, mitochondrial complexes with AsOR‐PL, and mitochondrial complexes plus AsOR‐LLO conjugate all containing the same number of mitochondria were injected intravenously. Animals were killed, and organs were removed and analyzed by quantitative polymerase chain reaction of mouse mitochondrial DNA, electron microscopy (EM), and in situ polymerase chain reaction and hybridization followed by immunohistochemical analyses. Results: Calculations revealed that approximately 27% of the total injected mitochondria was detected in the liver, while less than 2% was found in spleen, and < 1% in lungs. Immunohistochemistry showed that mouse mitochondrial DNA staining was minimal with mitochondrial complexes alone, strong periportal with mitochondrial complexes co‐injected with AsOR‐LLO, and absent with mitochondria alone. Conclusions: Targetable mitochondrial complexes can be delivered to rat liver, and the efficiency of that process is greatly enhanced by co‐injection of a targetable endosomal release agent, AsOR‐LLO. [ABSTRACT FROM AUTHOR]

We analyzed the association of the level of mRNA expression of the main endocytosis receptor LRP1 and actin-binding proteins (ezrin, profilin-1, cofilin-1, and adenylyl cyclase-associated protein 1) with the development and metastasis of laryngeal and laryngopharyngeal squamous cell carcinoma. The mRNA expression was evaluated in paired tissue samples using quantitative reverse transcription real-time PCR (RT-qPCR) and SYBR Green reagents. The study included 38 patients with stage T1-4N0-1M0 laryngeal and laryngopharyngeal squamous cell carcinoma and 10 patients with chronic hyperplastic laryngitis or grade II-III epithelial dysplasia. The expression of LRP1 in patients with laryngeal and laryngopharyngeal squamous cell carcinoma depended on the stage of the tumor process. Against the background of low expression of LRP1 mRNA, the relationship between cofilin 1 and profilin 1 expression became stronger (r=0.08; p=0.05) and a correlation between cofilin 1 and esrin expression (r=0.7; p=0.05) appeared. Studies on a larger patient cohort are required to make a definite conclusion on the role of LRP1 in the development of laryngeal and laryngopharyngeal squamous cell carcinoma. [ABSTRACT FROM AUTHOR]

• Construct an agent-target binding model based on stochastic differential equations. • Determine conditions to apply stochastic quasi steady state approximation. • Compare parameter estimation with maximum likelihood estimation and Euler–Maruyama approximation for sparse data. • Strengths and weaknesses of the reduced model for the endocytosis and lysosome processes using an age-structured model. • Comparing the reduced model with the full system of the released payload by identifying the mean retention time. In this paper, we propose mathematical models to describe receptor-mediated endocytosis processes. One is a stochastic differential model for the agent-target binding process. The mean extinction time and a standard variation over time profile are evaluated. The other is an age-structured model for demonstrating endocytosis and lysosome processes. A targeted drug delivery system has a complex process in how it is to deliver drug molecules in terms of administration, transportation in blood and across membranes to intracellular space, and inhibition to microtubule polymerization. In particular, receptor-mediated endocytosis of targeted therapeutic agents, such as antibody drug conjugates or ligand-targeted liposome encapsulated nanoparticles, is a key step in understanding the drug delivery mechanism. We discuss stochastic quasi steady state approximation when agent-target complex does not appreciably vary compared with the free agents. This reduces the number of the systems and the parameters; however, an initial time phase cannot be captured. In addition, we discuss the strengths and weaknesses when the age-structured model induces the reduced model compared with the full model that considers endocytosis and lysosome processes. If the total mean retention time until payload release in intracellular space is known, then the age-structured model with the Erlang distribution may fairly predict data of the released payload over time profile with far fewer parameters; however, induced compartments lose their physical meaning and describe only a delay. [ABSTRACT FROM AUTHOR]

We recently described a basic technology to efficiently combine compacted DNA with phospholipids and hydrophobic peptides, to produce homogenous complexes that are completely resistant to nuclease. We have developed this technology further to form gene delivery complexes that transfect cells effectively in vitro. In addition to plasmid DNA, the complexes contained two basic components: (i) a DNA compacting peptide (-CGKKKFKLKH), either conjugated to lipid or extended to contain (WLPLPWGW-) and (ii) either phosphatidylethanolamine or phosphatidylcholine. Complexes containing a 5.5-fold charge equivalence (peptide charge/DNA charge) of WLPLPWGWCGKKKFKLKH and 5 nmol dimyristoleoylphosphatidylethanolamine/µg DNA produced the highest luciferase gene expression, exceeding 1 × 109 relative light units/s/mg protein (>3 µg luciferase per mg protein). These complexes transfected OVCAR-3, COS-7 and HeLa cells at either similar or superior levels when compared to polyethylenimine or lipofectamine complexes. With green fluorescent protein reporter gene, >50% of HeLa cells were positive 30 h after addition of these complexes. Furthermore, these optimal complexes were the least sensitive to pre-treatment of cells with chloroquine, indicating efficient endosomal escape. Our results indicated that self-assembling complexes of plasmid DNA, amphiphilic peptide and phosphatidylethanolamine are highly effective non-viral gene delivery systems.

Owing to its intricate autoimmune pathophysiology and significant risks of progression to other rheumatic co-morbidities (i.e., osteoporosis and osteoarthritis), a plausible therapeutic regimen is mandatory for early-stage management of rheumatoid arthritis (RA). Nevertheless, the conventional therapeutic agents particularly the corticosteroids and disease-modifying anti-rheumatic drugs (DMARDs) have shown grander success in the treatment of RA; however, long-term use of these agents is also associated with serious adverse events. To combat these issues and optimize therapeutic efficacy, nanotechnology-based interventions have been emerged as viable option. While, nanomedicines signposted superiority over the conventional pharmacological moieties; there are still many pharmacokinetic and pharmacodynamic challenges to nanomedicines following their intravenous or intra-articular administration. To circumvent these challenges, significant adaptations such as PEGylation, surface conjugation of targeting ligand(s), and site- responsive behavior (i.e., pH-, biochemical-, or thermal-responsiveness) have been implemented. Besides, multi-functionalization of nanomedicines has been emerging as an exceptional strategy to overcome pharmacokinetic challenges, improve targetability to inflamed synovium, maximise internalisation into the activated macrophages, and improved therapeutic outcomes for treatment of RA. Therefore, this review aims to conceptualize and recapitulate the substantial evidences regarding the pharmacokinetic and pharmacodynamic superiority of multi-functionalized nanomedicines over the naked nanomedicines for site-selective targeting to inflamed synovium and rational treatment of RA and other rheumatic co-morbidities. Pharmaceutical sustainability of the multi-functionalized nanomedicines for improved biocompatibility, profound interaction with the targeting tissue/cells/sub-cellular domain, and diminished systemic toxicity has also been pondered. Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract Natural carbohydrate polymer-based nanoparticles have great biocompatibility that is required for the safe delivery of various drugs including nucleic acid therapeutics. Herein, we designed curdlan-based nanoparticles for cancer cell targeted delivery of short interfering RNA (siRNA). iRGD peptide conjugated 6-amino-6-deoxy curdlan specifically delivered siRNA to integrin expressing cancer cells. Incubation of cancer cells with free iRGD peptide competitively blocked cellular uptake of the iRGD functionalized curdlan nanoparticles. Chloroquine but not nystatin inhibited cellular uptake of iRGD functionalized curdlan nanoparticles, indicating that the iRGD peptide conjugated curdlan nanoparticles were internalized through the receptor (clathrin)-mediated endocytosis. Moreover, a disease related gene Plk1 was substantially knocked down by siRNA carried by 6AC-iRGD nanoparticles in HepG2 cells. Our data suggested that iRGD functionalized curdlan may provide a biocompatible carrier for siRNA delivery. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The mechanism of the uptake and drug release of HA nanoparticles are elaborated. • The synthesis of HA nanoparticles is reviewed in detail from several aspects. • The latest applications of HA nanoparticles in delivery are summarized clearly. • Some modification strategies are discussed for further improving the targeting and drug releasing characteristics. Abstract In recent years, biomacromolecules have been widely used in anti-tumor delivery systems due to the biocompatibility and biodegradability. However, their applications are limited due to the lack of specific targeting. Hyaluronic acid (HA) is a natural polysaccharide and presents in extracellular matrix and synovial fluid which can specifically recognize receptors over-expressed by tumor cells. In addition, they can self-assemble into nanoparticles. HA nanoparticles provide new hierarchical targeting strategies: passively targeting tumor tissue by enhanced permeability and retention effect, actively targeting tumor cells by cluster determinant 44 (CD44) receptor, and then entering cells through receptor-mediated endocytosis. In this review, the synthesis of HA nanoparticles is described in detail from several aspects and applications are also discussed for improving the delivery of hydrophobic drugs, nucleic acids and photosensitizers into the tumor cells. In addition, the modification of HA for improving the targeting and drug releasing characteristics are also discussed. [ABSTRACT FROM AUTHOR]

A role for dynamin in clathrin-mediated endocytosis is now well established. However, mammals express three closely related, tissue-specific dynamin isoforms, each with multiple splice variants. Thus, an important question is whether these isoforms and splice variants function in vesicle formation from distinct intracellular organelles. There are conflicting data as to a role for dynamin-2 in vesicle budding from the TGN. To resolve this issue, we compared the effects of overexpression of dominant-negative mutants of dynamin-1 (the neuronal isoform) and dynamin-2 (the ubiquitously expressed isoform) on endocytic and biosynthetic membrane trafficking in HeLa cells and polarized MDCK cells. Both dyn1(K44A) and dyn2(K44A) were potent inhibitors of receptor-mediated endocytosis; however neither mutant directly affected other membrane trafficking events, including transport mediated by four distinct classes of vesicles budding from the TGN. Dyn2(K44A) more potently inhibited receptor-mediated endocytosis than dyn1(K44A) in HeLa cells and at the basolateral surface of MDCK cells. In contrast, dyn1(K44A) more potently inhibited endocytosis at the apical surface of MDCK cells. The two dynamin isoforms have redundant functions in endocytic vesicle formation, but can be targeted to and function differentially at subdomains of the plasma membrane.

Scavenger receptors perform essential functions, critical to maintaining mammalian physiologic homeostasis by continuously clearing vast numbers of biomolecules from blood, interstitial fluid and lymph. Stabilin-2 (Stab2) and the Hyaluronic Acid Receptor for Endocytosis (HARE), a proteolytic isoform of Stab2, are important scavenger receptors responsible for the specific binding and internalization (leading to degradation) of 22 discrete molecules, macromolecular complexes and cell types. One-third of these ligands are glycosaminoglycans (GAGs). Full-length Stab2, but not HARE, mediates efficient phagocytosis of apoptotic cells and bacteria via binding to target surface ligands. HARE, the C-terminal half of Stab2, mediates endocytosis of all the known soluble ligands. HA was the first ligand identified, in 1981, prior to receptor purification or cloning. Seven other GAG ligands were subsequently identified: heparin, dermatan sulfate, chondroitin and chondroitin sulfates A, C, D and E. Synthetic dextran sulfate is also a GAG mimic and ligand. HARE signaling during HA endocytosis was first discovered in 2008, and we now know that activation of HARE/Stab2 signaling is stimulated by receptor-mediated endocytosis or phagocytosis of many, but not all, of its ligands. This review focuses on the HARE-mediated GAG activation of intracellular signaling, particularly the Extracellular Signal-Regulated Kinase 1/2 pathway.

Mammalian cell membranes are very dynamic where they respond to several environmental stimuli by rearranging the membrane composition by basic biological processes, including endocytosis. In this context, receptor-mediated endocytosis, either clathrin-dependent or caveolae-dependent, is involved in different physiological and pathological conditions. In the last years, an important amount of evidence has been reported that kidney function involves the modulation of different types of endocytosis, including renal protein handling. In addition, the dysfunction of the endocytic machinery is involved with the development of proteinuria as well as glomerular and tubular injuries observed in kidney diseases associated with hypertension, diabetes, and others. In this present review, we will discuss the mechanisms underlying the receptor-mediated endocytosis in different glomerular cells and proximal tubule epithelial cells as well as their modulation by different factors during physiological and pathological conditions. These findings could help to expand the current understanding regarding renal protein handling as well as identify possible new therapeutic targets to halt the progression of kidney disease., (Copyright © 2024. Published by Elsevier Inc.)