Studies of Mucosal Irritation and Cellular Uptake Mechanisms of Xingnaojing Nanoemulsion

Abstract Xingnaojing (XNJ) injection was used to treat pneumonia and stroke in clinic in China, but with poor patient compliance. Xingnaojing nanoemulsion for intranasal delivery was developed to improve it. This article tried to evaluate the mucosal irritation of Xingnaojing nanoemulsion and investigate cellular uptake mechanism of its encapsulated lipophilic drugs. The toad palate model and rat nasal mucosa model were used to study the nasal ciliotoxicity and nasal mucosal irritation of nanoemulsion to evaluate its safety intranasally. The cellular uptake mechanism was studied by Calu-3 cell model. Coumarin 6 was encapsulated in nanoemulsion and the endocytic pathways were studied by cellular uptake experiments after being treated with different inhibitors. In toad palate model, the cilia movement of Xingnaojing nanoemulsion group last for 467.40 ± 39.02 min, which was obviously longer than deoxycholate group (90.60 ± 15.40 min). Studies on rats showed that the damage caused by nanemulsion is capable of being recovered. Nanoemulsion uptake was reduced obviously when cells were treated with wortmannin, and it also decreased about 13% when the temperature reduced from 37ºC to 4ºC. Mucosal irritation caused by nanoemulsion is low and the damage is recoverable. The cellular uptake of Xingnaojing nanoemulsion is energy-dependent, and macropinocytosis was the most important pathway for cellular uptake.

Morphology and morphogenesis of SARS-CoV-2 in Vero-E6 cells

BACKGROUND The coronaviruses (CoVs) called the attention of the world for causing outbreaks of severe acute respiratory syndrome (SARS-CoV), in Asia in 2002-03, and respiratory disease in the Middle East (MERS-CoV), in 2012. In December 2019, yet again a new coronavirus (SARS-CoV-2) first identified in Wuhan, China, was associated with a severe respiratory infection, known today as COVID-19. This new virus quickly spread throughout China and 30 additional countries. As result, the World Health Organization (WHO) elevated the status of the COVID-19 outbreak from emergency of international concern to pandemic on March 11, 2020. The impact of COVID-19 on public health and economy fueled a worldwide race to approve therapeutic and prophylactic agents, but so far, there are no specific antiviral drugs or vaccines available. In current scenario, the development of in vitro systems for viral mass production and for testing antiviral and vaccine candidates proves to be an urgent matter. OBJECTIVE The objective of this paper is study the biology of SARS-CoV-2 in Vero-E6 cells at the ultrastructural level. METHODS In this study, we documented, by transmission electron microscopy and real-time reverse transcription polymerase chain reaction (RT-PCR), the infection of Vero-E6 cells with SARS-CoV-2 samples isolated from Brazilian patients. FINDINGS The infected cells presented cytopathic effects and SARS-CoV-2 particles were observed attached to the cell surface and inside cytoplasmic vesicles. The entry of the virus into cells occurred through the endocytic pathway or by fusion of the viral envelope with the cell membrane. Assembled nucleocapsids were verified inside rough endoplasmic reticulum cisterns (RER). Viral maturation seemed to occur by budding of viral particles from the RER into smooth membrane vesicles. MAIN CONCLUSIONS Therefore, the susceptibility of Vero-E6 cells to SARS-CoV-2 infection and the viral pathway inside the cells were demonstrated by ultrastructural analysis.

Research progress of Rab proteins in neurodegenerative diseases / 生理学报

As a member of the Ras superfamily, Rab proteins are small GTP-binding proteins. In the process of endocytosis of macromolecules and substances delivery between organelles, Rab proteins act on vesicle formation, transport, tethering and fusion by recruiting their effectors, therefore being key regulatory factors in vesicle trafficking. Disturbance of localizations and functions of Rab proteins and their effectors are involved in the pathogenesis of several diseases. This review focuses on the main functions of Rab proteins and their possible roles in the onset and progression of neurodegenerative diseases including Parkinson's disease, Alzheimer's disease, and Huntington's disease.

Scavenger Receptor Class A to E Involved in Various Cancers / 전남의대학술지

Scavenger receptors typically bind to multiple ligands on a cell surface, including endogenous and modified host-derived molecules and microbial pathogens. They promote the elimination of degraded or harmful substances such as non-self or altered-self targets through endocytosis, phagocytosis, and adhesion. Currently, scavenger receptors are subdivided into eight classes based on several variations in their sequences due to alternative splicing. Since recent studies indicate targeting scavenger receptors has been involved in cancer prognosis and carcinogenesis, we will focus on the current knowledge about the emerging role of scavenger receptor classes A to E in cancer progression.

Mediated pathways of exosomes uptake by stem cells of apical papilla / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the uptake of exosomes by stem cells from apical papilla (SCAP), thus to provide experimental basis for mechanism of the exosomes endocytosis by SCAP.@*METHODS@#(1) Exosomes of dental pulp stem cells (DPSCs) were isolated by hypercentrifugation combined with ultrafiltration method. The exosomes were identified by transmission electron microscopy, nanoparticle tracking analysis and western blot. (2) PKH-26 membrane labeling technology was used to mark the DPSCs derived exosomes. The labeled exosomes were co-cultured with SCAP at 37 °C as positive control group, and co-cultured with SCAP at 4 °C as the low-temperature treatment group, while the negative control group was set up. (3) Using clathrin-mediated endocytosis inhibitor chlorpromazine (CPZ, 10 μmol /L) as CPZ group, caveolae-mediated endocytosis Genistein (200 μmol/L) as Genistein group, and macropinocytosis inhibitor LY294002 (50 μmol/L) as LY294002 group to treat the SCAP respectively. Solvent control group (DMSO group) was set. Immunofluorescence staining was used to detect the red fluorescence SCAP and flow cytometry was used to analyze the proportion of SCAP labeled with red fluorescence.@*RESULTS@#(1) The bilayer membrane and cup-shaped appearance of representative exosomes were observed. The peak of the size of DPSCs-derived exosomes was at 144 nm. The exosomes expressed exosomal marker proteins TSG101 and CD63, but not GAPDH which was the cellular internal control protein. (2) Immunofluorescence staining showed that after being co-cultured at 37 °C for 6 hours, red fluorescence could be detected in SCAP but it could not be detected after being co-cultured at 4 °C for 6 hours. After endocytosis inhibition, the red fluorescence in SCAP was reduced. Flow cytometry showed that the proportion of SCAP labeled with red fluorescence in positive group was 35.0%, in negative control group was 0.5%, and in solvent control group was 29.7%, in CPZ group, Genistein group and Genistein group were reduced to 13.7%, 16.6%, and 20.9%, respectively.@*CONCLUSION@#SCAP could uptake the DPSCs derived exosomes, and low temperature could inhibit this process. The exosomes uptake of SCAP was mediated by the clathrin endocytosis pathway, caveolae-mediated endocytosis and macropinocytosis pathway.

Method for active ingredients' in vivo target identification of traditional Chinese medicine using magnetic nanoparticles / 中国中药杂志

Target identification is an important prerequisite for the study of medicine action mechanism. Currently,drug target identification is mostly based on various cell models in vitro. However,the growth microenvironment,nutrition metabolism,biological properties as well as functions are quite different between in vitro cell culture and physiological environment in vivo; wherefore,it is a challenging scientific issue to establish an effective method for identifying drug targets in vivo condition. In this study,we successfully prepared a kind of magnetic nanoparticles( MNPs) which can be chemically modified by the hydroxyl structure of natural bioactive compound echinacoside( ECH) via the epoxy group label on the surface of MNPs. Therefore,organ-selective and recoverable nanoscale target-recognizing particles were prepared. We then intravenously injected the ECH-binding MNPs into rats and distributed them to specific organs in vivo. After cell endocytosis,ECH-binding MNPs captured target proteins in situ for further analysis. Based on this method,we discovered several potential target proteins in the spleen lysates for ECH,and preliminarily clarified the immuno-regulation mechanism of ECH. Collectively,our strategy developed a proof-of-concept technology using nanoparticles for in vivo target identification,and also provided a feasible approach for drug target prediction and pharmacological mechanism exploration.

Advances in the research and application of cell penetrating peptides / 生物工程学报

Cell-penetrating peptides (CPPs) are short peptides that can penetrate the cell membrane or tissue barrier. CPPs can deliver a variety of biomacromolecules, such as proteins, RNA and DNA, into cells to produce intracellular functional effects. Endocytosis and direct penetration have been suggested as the two major uptake mechanisms for CPPs-mediated cargo delivery. Compared with other non-natural chemical molecules-based delivery reagents, the CPPs have better biocompatibility, lower cytotoxicity, are easily degraded after cargo delivery, and can be fused and recombined expressed with bioactive proteins. Because of these advantages, the CPPs have become an important potential tool for delivery of developing drugs which targets intracellular factors. As a novel delivery tool, the CPPs also show promising application prospects in biomedical researches. This review summarized recent advances regarding the classification characteristics, the cellular uptake mechanisms and therapeutic application potentials of CPPs.

Justicidin A Reduces β-Amyloid via Inhibiting Endocytosis of β-Amyloid Precursor Protein

β-amyloid precursor protein (APP) can be cleaved by α-, and γ-secretase at plasma membrane producing soluble ectodomain fragment (sAPPα). Alternatively, following endocytosis, APP is cleaved by β-, and γ-secretase at early endosomes generating β-amyloid (Aβ), the main culprit in Alzheimer's disease (AD). Thus, APP endocytosis is critical for Aβ production. Recently, we reported that Monsonia angustifolia, the indigenous vegetables consumed in Tanzania, improved cognitive function and decreased Aβ production. In this study, we examined the underlying mechanism of justicidin A, the active compound of M. angustifolia, on Aβ production. We found that justicidin A reduced endocytosis of APP, increasing sAPPα level, while decreasing Aβ level in HeLa cells overexpressing human APP with the Swedish mutation. The effect of justicidin A on Aβ production was blocked by endocytosis inhibitors, indicating that the decreased APP endocytosis by justicidin A is the underlying mechanism. Thus, justicidin A, the active compound of M. angustifolia, may be a novel agent for AD treatment.

Role of endocytosis in cell surface CXC chemokine receptor 4 expression of stem cells from apical papilla / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the change of cell surface CXC chemokine receptor 4 (CXCR4) expression of stem cells from apical papilla (SCAP) after the inhibition of endocytotic pathway, thus to provide experimental basis for the mechanism of SCAP migration.@*METHODS@#The immunofluorescence analysis was conducted to examine the co-expression of CXCR4 and endocytotic compartments, including early endosomes, recycling endosomes and lysosomes in SCAP. Several Rab proteins were applied as markers of organelles in the endocytotic pathway, including Rab5 for early endosomes, Rab11A for recycling endosomes, and Lamp1 for lysosomes. The co-localization of CXCR4 with these endodontic compartments was further observed by proximity ligation assay (PLA). SCAP was treated with two kinds of endocytotic inhibitors, Blebbistatin and Dynasore, at a concentration of 80 μmol/L, respectively. The conditioning time was 1 hour. Flow cytometry was carried out to evaluate the proportion of SCAP that expressed CXCR4 on cell surface. The data were analysed by analysis of variance (ANOVA).@*RESULTS@#The red staining of CXCR4 on immunofluorescence confocal microscopy predominantly overlapped with the green staining of Rab5 and Rab11A, and partly overlapped with Lamp1. It indicated that most CXCR4 molecules were located in early endosomes and recycling endosomes, and some were located in lysosomes. The PLA results revealed that the co-localizaiton of CXCR4 with endocytotic compartments could be observed in early endosomes, recycling endosomes and lysosomes. According to the results of flow cytometry, the proportion of SCAP that expressed CXCR4 on cell surface was as low as 0.13%±0.10%. After the inhibition of endocytosis by pretreating the cells with the following two inhibitors, Blebbistatin and Dynasore, the percentage of SCAP that positively expressed CXCR4 on cell surface was significantly increased to 13.34%±1.31% in Blebbistatin group and 4.03%±0.92% in Dynasore group (F=16.721, P<0.001). Moreover, the number of SCAP that expressed CXCR4 on cell surface in Blebbistatin group was significantly higher than that in Dynasore group (P<0.001).@*CONCLUSION@#The inhibition of endocytotic pathway could increase the number of SCAP that expressed CXCR4 on cell surface, and provide potency for the migration of SCAP.

Enhanced apoptosis and inhibition of gastric cancer cell invasion following treatment with LDH@Au loaded Doxorubicin

Background: The suppression of cancer cell growth and invasion has become a challenging clinical issue. In this study, we used nanotechnology to create a new drug delivery system to enhance the efficacy of existing drugs. We developed layered double hydroxide by combing Au nanosol (LDH@Au) and characterized the compound to prove its function as a drug delivery agent. The anti-cancer drug Doxorubicin was loaded into the new drug carrier to assess its quality. We used a combination of apoptosis assays, cell cycle assays, tissue distribution studies, cell endocytosis, transwell invasion assays, and immunoblotting to evaluate the characteristics of LDH@Au as a drug delivery system. Results: Our results show that the LDH@Au-Dox treatment significantly increased cancer cell apoptosis and inhibited cell invasion compared to the control Dox group. Additionally, our data indicate that LDH@Au-Dox has a better target efficiency at the tumor site and improved the following: cellular uptake, anti-angiogenesis action, changes in the cell cycle, and increased caspase pathway activation. Conclusions: Our findings suggest the nano drug is a promising anti-cancer agent and has potential clinical applications.

El síndrome urémico hemolítico y manejo renal de proteínas / Hemolytic uremic syndrome and renal handling of proteins

El síndrome urémico hemolítico (SUH) está definido por la tríada de anemia hemolítica microangiopática, trombocitopenia e insuficiencia renal aguda. En Argentina constituye la primera causa de insuficiencia renal aguda en pediatría. Aproximadamente, del 2% al 4% de los pacientes mueren durante la fase aguda de la enfermedad, y solo un tercio del 96% restante que sobrevive lo hace con secuelas renales, como la persistencia de la proteinuria. Un individuo adulto sano filtra alrededor de 5000 mg/día de proteínas, si bien la excreción en orina es escasa (150 mg/día). La escasa cantidad de proteínas excretadas indica la presencia de un mecanismo de reabsorción a nivel del túbulo proximal. Por lo tanto, la reabsorción tubular renal desempeña un papel muy importante ya que, ante una función glomerular normal, es el principal mecanismo encargado de evitar la depleción proteica corporal. Desde hace aproximadamente 30 años se sabe que la albúmina es reabsorbida en el túbulo proximal. La reabsorción proteica se produce por un mecanismo de endocitosis mediada por el receptor dependiente de clatrina y por endocitosis de fase líquida. Clásicamente se ha descrito que el mecanismo básico del daño renal en el SUH típico y en el atípico es una microangiopatía trombótica, pero de diferentes causas. Sin embargo, debe tenerse en cuenta que la fisiopatología de esta enfermedad es más compleja de lo que se creía, ya que la alteración tubular que surge va a evolucionar en fallas en el mecanismo de endocitosis de proteínas que se suman a las eliminadas por las alteraciones a nivel de la barrera de filtración glomerular.

Hemolytic uremic syndrome (HUS) is defined by the triad of hemolytic anemia microangiopathic, thrombocytopenia and acute renal failure. In Argentina it constitutes the first cause of acute renal failure in Pediatrics. Approximately 2-4% of patients die during the acute phase of the disease, and only a third of the remaining 96% survive with renal sequelae, such as the persistence of proteinuria. A healthy adult filters around 5000 mg/day of proteins, with an excretion in urine of 150 mg/day. The little quantity of proteins excreted indicates the presence of a reabsorption mechanism at the level of the proximal tubule. Therefore, the tubular reabsorption plays a very important role since it is the main mechanism responsible for preventing the depletion of protein. For approximately 30 years, it has been known that albumin is reabsorbed in the proximal tubule. Protein reabsorption occurs by a clathrin-dependent receptor mediated endocytosis mechanism and by fluid phase endocytosis. The basic mechanism of renal damage in typical and atypical HUS has been described as a thrombotic microangiopathy, but of different causes. However, the pathophysiology of this disease is more complex than what was believed since the emerging tubular alteration will ewvolve into failures of the protein endocytosis mechanism that are added to the alterations at the level of the glomerular filtration barrier.

Novel Cell Permeable Peptide Based on Multi Basic Furin-dependent Cleavage Site of Respiratory Syncytial Virus Fusion Protein

Cell permeable peptide (CPP) is able to transport itself or conjugated molecules such as nucleotides, peptides, and proteins into cells. Since short peptide of human immunodeficiency virus-1 Tat has been discovered as CPP, it has been continuously studied for their ability to transport heterologous cargoes into cells. In this study, we have focused on the fusion protein of respiratory syncytial virus (RSV), which has six basic amino acids in multi basic furin-dependent cleavage site (MBFCS) required to be cationic CPP. To develop more efficient CPP, the sequence, which linked two MBFCS, was synthesized (called RS-CPP). To assess cell permeable efficiency of RS-CPP or MBFCS, the peptides was conjugated with fluorescein isothiocyanate, and cell permeable efficiency was measured by fluorescence-activated cell sorting. Cell permeability of RS-CPP or MBFCS was increased in a dose-dependent manner, but RS-CPP showed more efficient cell permeability than MBFCS in MDCK, HeLa, Vero E6, and A549 cells. To evaluate whether RS-CPP can transport its conjugated functional peptide (VIVIT) in CD8+ T cell, it was confirmed that IL-2 and β-galactosidase expression were significantly inhibited through selective block of nuclear factor activated T-cell. To investigate endocytic pathways, Cre-mediated DNA recombination (loxP-STOP-loxP-LacZ reporter system) was investigated with divergent endocytosis inhibitors in TE671 cells, and RS-CPP endocytosis is occurred via binding cell surface glycosaminoglycan and clathrin-mediated endocytosis, or macropinocytosis. These results indicated that RS-CPP could be a novel cationic CPP, and it would help understanding for delivery of biologically functional molecules based on viral basic amino acids.

Ubiquitin C-terminal Hydrolase L1 Regulates Lipid Raft-dependent Endocytosis

Ubiquitin C-terminal hydrolase L1 (UCH-L1) is a deubiquitinating enzyme that is highly expressed in neurons, and gathering evidence indicates that UCH-L1 may play pathogenic roles in many neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease (PD). Additionally, lipid rafts have attracted interest in neurodegeneration as playing a common role in many neurodegenerative diseases. In the present study, we demonstrated that UCH-L1 associates with lipid rafts as with other PD-associated gene products. In addition, UCH-L1 regulates lipid raft-dependent endocytosis and it is not dependent on the expression and degradation of caveolin-1 or flotillin-1. Finally, UCH-L1 regulates cell-to-cell transmission of α-synuclein. This study provides evidence that many PD-associated gene products share common signaling pathways to explain the pathogenesis of PD.

Uptake of DNA by cancer cells without a transfection reagent

BACKGROUND: Cancer cells exhibit elevated levels of glucose uptake and may obtain pre-formed, diet-derived fatty acids from the bloodstream to boost their rapid growth; they may also use nucleic acid from their microenvironment. The study of processing nucleic acid by cancer cells will help improve the understanding of the metabolism of cancer. DNA is commonly packaged into a viral or lipid particle to be transferred into cells; this process is called transfection in laboratory. Cancer cells are known for having gene mutations and the evolving ability of endocytosis. Their uptake of DNAs might be different from normal cells; they may take in DNAs directly from the environment. In this report, we studied the uptake of DNAs in cancer cells without a transfection reagent. METHODS: A group of DNA fragments were prepared with PCR and labeled with isotope phosphorous-32 to test their uptake by Huh 7 (liver cancer) and THLE3 (normal liver cells) after incubation overnight by counting radioactivity of the cells' genomic DNA. Multiple cell lines including breast cancer and lung cancer were tested with the same method. DNA molecules were also labeled with fluorescence to test the location in the cells using a kit of "label it fluorescence in situ hybridization (FISH)" from Mirus (USA). RESULTS: The data demonstrated that hepatocellular carcinoma cells possess the ability to take in large DNA fragments directly without a transfection reagent whereas normal liver cells cannot. Huh7 and MDA-MB231 cells displayed a significantly higher Rhodamine density in the cytoplasmic phagosomes and this suggests that the mechanism of uptake of large DNA by cancer cells is likely endocytosis. The efficacy of uptake is related to the DNA's size. Some cell lines of lung cancer and breast cancer also showed similar uptake of DNA. CONCLUSIONS: In the present study, we have revealed the evidence that some cancer cells, but not nontumorigenic cells, can take DNA fragments directly from the environment without the aid of the transfecting reagent.

Versatile Functions of Caveolin-1 in Aging-related Diseases / 전남의대학술지

Caveolin-1 (Cav-1) is a trans-membrane protein that is a major component of the caveolae structure on the plasma membrane. Cav-1 is involved in the regulation of various cellular processes, including cell growth, differentiation, endocytosis, and in particular it has been implied in cellular senescence. Here we review current knowledge about Cav-1 in cellular signaling and discuss the role of Cav-1 in aging-related diseases.

Cryo-EM structures of the mammalian endo-lysosomal TRPML1 channel elucidate the combined regulation mechanism

TRPML1 channel is a non-selective group-2 transient receptor potential (TRP) channel with Ca permeability. Located mainly in late endosome and lysosome of all mammalian cell types, TRPML1 is indispensable in the processes of endocytosis, membrane trafficking, and lysosome biogenesis. Mutations of TRPML1 cause a severe lysosomal storage disorder called mucolipidosis type IV (MLIV). In the present study, we determined the cryo-electron microscopy (cryo-EM) structures of Mus musculus TRPML1 (mTRPML1) in lipid nanodiscs and Amphipols. Two distinct states of mTRPML1 in Amphipols are added to the closed state, on which could represent two different confirmations upon activation and regulation. The polycystin-mucolipin domain (PMD) may sense the luminal/extracellular stimuli and undergo a "move upward" motion during endocytosis, thus triggering the overall conformational change in TRPML1. Based on the structural comparisons, we propose TRPML1 is regulated by pH, Ca, and phosphoinositides in a combined manner so as to accommodate the dynamic endocytosis process.

Inhibitory Effects of Methanol Extract from Nardostachys chinensis on 27-hydroxycholesterol-induced Differentiation of Monocytic Cells

27-Hydroxycholesterol (27OHChol) has been reported to induce differentiation of monocytic cells into a mature dendritic cell phenotype. We examined the effect of methanol extract of Nardostachys chinensis (Nard) on 27OHChol-induced differentiation using THP-1, a human monocytic cell line. Treatment of monocytic cells with methanol extract of Nard resulted in decreased transcription and surface expression of CD80, CD83, and CD88 elevated by 27OHChol in a dose-dependent manner. Surface levels of MHC class I and II molecules elevated by 27OHChol were also reduced to basal levels by treatment with the Nard extract. Decreased endocytosis activity caused by 27OHChol was recovered by treatment with the Nard extract. CD197 expression and cell attachment were attenuated by the Nard extract. In addition, levels of transcription and surface expression of CD molecules involved in atherosclerosis, such as CD105, CD137, and CD166 upregulated by 27OHChol were significantly decreased by treatment with methanol extract of Nard. These results indicate that methanol extract of Nard down-regulates 27OHChol-induced differentiation of monocytic cells into a mature dendritic cell phenotype and expression of CD molecules associated with atherosclerosis. The current study suggests that biological activity of oxygenated cholesterol derivatives can be inhibited by herbal medication.

Multifactorial Regulation of G Protein-Coupled Receptor Endocytosis

Endocytosis is a process by which cells absorb extracellular materials via the inward budding of vesicles formed from the plasma membrane. Receptor-mediated endocytosis is a highly selective process where receptors with specific binding sites for extracellular molecules internalize via vesicles. G protein-coupled receptors (GPCRs) are the largest single family of plasma-membrane receptors with more than 1000 family members. But the molecular mechanisms involved in the regulation of GPCRs are believed to be highly conserved. For example, receptor phosphorylation in collaboration with β-arrestins plays major roles in desensitization and endocytosis of most GPCRs. Nevertheless, a number of subsequent studies showed that GPCR regulation, such as that by endocytosis, occurs through various pathways with a multitude of cellular components and processes. This review focused on i) functional interactions between homologous and heterologous pathways, ii) methodologies applied for determining receptor endocytosis, iii) experimental tools to determine specific endocytic routes, iv) roles of small guanosine triphosphate-binding proteins in GPCR endocytosis, and v) role of post-translational modification of the receptors in endocytosis.

Versatile Functions of Caveolin-1 in Aging-related Diseases / 전남의대학술지

Caveolin-1 (Cav-1) is a trans-membrane protein that is a major component of the caveolae structure on the plasma membrane. Cav-1 is involved in the regulation of various cellular processes, including cell growth, differentiation, endocytosis, and in particular it has been implied in cellular senescence. Here we review current knowledge about Cav-1 in cellular signaling and discuss the role of Cav-1 in aging-related diseases.

Interaction between functional nano-hydroxyapatite and cells and the underlying mechanisms / 中南大学学报(医学版)

OBJECTIVE@#To explore the interaction between arginine functionalized hydroxyapatite (HAP/Arg) nanoparticles and endothelial cells, and to investigate mechanisms for endocytosis kinetics and endocytosis.
@*METHODS@#Human umbilical vein endothelial cells (HUVECs) were selected as the research model.Cellular uptake of HAP/Arg nanoparticles were observed by laser scanning confocal microscopy.Average fluorescence intensity of cells after ingestion with different concentrations of HAP/Arg nanoparticles were determined by flow cytometer and atomic force microscopy.
@*RESULTS@#The HAP/Arg nanoparticles with doped terbium existed in cytoplasm, and most of them distributed around the nucleus area after cellular uptake by HUVECs. Cellular uptake process of HAP/Arg nanoparticles in HUVECs was in a time and concentration dependent manner. 4 h and 50 mg/L was the best condition for uptake. HAP/Arg nanoparticles were easier to be up-taken into the cells than HAP nanoparticles without arginine functionalized.
@*CONCLUSION@#HAP/Arg nanoparticles are internalized by HUVECs cells through an active transport and energy-dependent endocytosis process, and it is up-taken by cells mainly through caveolin-mediated endocytosis, but the clathrin-dependent endocytic pathway is also involved..