MSC-derived exosomes protect auditory hair cells from neomycin-induced damage via autophagy regulation

Background Sensorineural hearing loss (SNHL) poses a major threat to both physical and mental health; however, there is still a lack of effective drugs to treat the disease. Recently, novel biological therapies, such as mesenchymal stem cells (MSCs) and their products, namely, exosomes, are showing promising therapeutic potential due to their low immunogenicity, few ethical concerns, and easy accessibility. Nevertheless, the precise mechanisms underlying the therapeutic effects of MSC-derived exosomes remain unclear. Results Exosomes derived from MSCs reduced hearing and hair cell loss caused by neomycin-induced damage in models in vivo and in vitro. In addition, MSC-derived exosomes modulated autophagy in hair cells to exert a protective effect. Mechanistically, exogenously administered exosomes were internalized by hair cells and subsequently upregulated endocytic gene expression and endosome formation, ultimately leading to autophagy activation. This increased autophagic activity promoted cell survival, decreased the mitochondrial oxidative stress level and the apoptosis rate in hair cells, and ameliorated neomycin-induced ototoxicity. Conclusions In summary, our findings reveal the otoprotective capacity of exogenous exosome-mediated autophagy activation in hair cells in an endocytosis-dependent manner, suggesting possibilities for deafness treatment.

YULINK regulates vascular formation in zebrafish and HUVECs

BACKGROUND: The distinct arterial and venous cell fates are dictated by a combination of various genetic factors which form diverse types of blood vessels such as arteries, veins, and capillaries. We report here that YULINK protein is involved in vasculogenesis, especially venous formation. METHODS: In this manuscript, we employed gene knockdown, yeast two-hybrid, FLIM-FRET, immunoprecipitation, and various imaging technologies to investigate the role of YULINK gene in zebrafish and human umbilical vein endothelial cells (HUVECs). RESULTS: Knockdown of YULINK during the arterial-venous developmental stage of zebrafish embryos led to the defective venous formation and abnormal vascular plexus formation. Knockdown of YULINK in HUVECs impaired their ability to undergo cell migration and differentiation into a capillary-like tube formation. In addition, the phosphorylated EPHB4 was decreased in YULINK knockdown HUVECs. Yeast two-hybrid, FLIM-FRET, immunoprecipitation, as well as imaging technologies showed that YULINK colocalized with endosome related proteins (EPS15, RAB33B or TICAM2) and markers (Clathrin and RHOB). VEGF-induced VEGFR2 internalization was also compromised in YULINK knockdown HUVECs, demonstrating to the involvement of YULINK. CONCLUSION: This study suggests that YULINK regulates vasculogenesis, possibly through endocytosis in zebrafish and HUVECs. Key points Knockdown of YULINK with morpholino in embryos of double transgenic zebrafish exhibited abnormal venous formation. Tube formation and phosphorylated EPHB4 were decreased in YULINK knockdown HUVECs. FLIM-FRET, immunoprecipitation, as well as other imaging technologies showed that YULINK colocalized with endosome related proteins (EPS15, RAB33B and TICAM2) and endosome markers (Clathrin and RHOB). Knockdown of YULINK decreased the internalization of VEGF and VEGFR2 in HUVECs.

DYRK1-mediated phosphorylation of endocytic components is required for extracellular lumen expansion in ascidian notochord

BACKGROUND: The biological tube is a basal biology structure distributed in all multicellular animals, from worms to humans, and has diverse biological functions. Formation of tubular system is crucial for embryogenesis and adult metabolism. Ascidian Ciona notochord lumen is an excellent in vivo model for tubulogenesis. Exocytosis has been known to be essential for tubular lumen formation and expansion. The roles of endocytosis in tubular lumen expansion remain largely unclear. RESULTS: In this study, we first identified a dual specificity tyrosine-phosphorylation-regulated kinase 1 (DYRK1), the protein kinase, which was upregulated and required for ascidian notochord extracellular lumen expansion. We demonstrated that DYRK1 interacted with and phosphorylated one of the endocytic components endophilin at Ser263 that was essential for notochord lumen expansion. Moreover, through phosphoproteomic sequencing, we revealed that in addition to endophilin, the phosphorylation of other endocytic components was also regulated by DYRK1. The loss of function of DYRK1 disturbed endocytosis. Then, we demonstrated that clathrin-mediated endocytosis existed and was required for notochord lumen expansion. In the meantime, the results showed that the secretion of noto-chord cells is vigorous in the apical membrane. CONCLUSIONS: We found the co-existence of endocytosis and exocytosis activities in apical membrane during lumen formation and expansion in Ciona notochord. A novel signaling pathway is revealed that DYRK1 regulates the endocytosis by phosphorylation that is required for lumen expansion. Our finding thus indicates a dynamic balance between endocytosis and exocytosis is crucial to maintain apical membrane homeostasis that is essential for lumen growth and expansion in tubular organogenesis.

Effects of Interaction Between Carbon Nanotubes on Membrane-Wrapped Carbon Nanotubes / 医用生物力学

Objective For the system of two single-walled carbon nanotubes (CNTs) placed in parallel onto a cell membrane, effects of the interaction between carbon nanotubes on wrapping manner of carbon tubes by the membrane were investigated, and the energy-optimized configurations were obtained. Methods A physical model for membrane-wrapped CNTs considering the interaction between two CNTs, and parameters describing the morphology of cell membrane and positions of CNTs were introduced. The Helfrich model based on continuum mechanics was used to calculate the membrane’s bending energy and the Lennard-Jones potential was introduced to describe the interaction between CNTs. Free energy of the system at different distances of NTs was calculated by the look-up table method, and the typical configurations of the membrane-wrapped CNTs was obtained. Results Compared with the case wherein the interaction between CNTs was not considered, the free energy profile of the system significantly changed. Deep well appeared on energy curve, when the distance between CNTs of carbon was 0.3 times of the tube diameter; as the distance between CNTs increased, the energy returned to the case wherein the interaction between CNTs was not considered. Conclusions With introduction of the interaction between CNTs, the wrapping manner of CNTs by the cell membrane changed, and the two CNTs tended to contact during their endocytosis. These results provide theoretical references for understanding and developing novel nanotube-based system for drug delivery.

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.

Cellular endocytosis and exocytosis of soluble uranium and its damage to HK-2 cells / 中国辐射卫生

Objective To investigate the endocytosis and exocytosis of soluble uranium in human kidney proximal tubular epithelial (HK-2) cells and the cytotoxicity after uranium exposure. Methods Cell Counting Kit-8 assay was used to determine the cell viability after different concentrations of uranium exposure, and optical microscopy and transmission electron microscopy were used to observe the changes in cells after uranium exposure. Inductively coupled plasma mass spectrometry was used to monitor the endocytosis and exocytosis of uranium over time by cells. Flow cytometry was used to assess the changes in cell cycle and apoptosis after uranium exposure. Results After uranium exposure, HK-2 cells showed dose-dependent damage; cell cycle was arrested in G1 phase; cell apoptosis and necrosis occurred; cell proliferation was inhibited. The content of endocytic uranium increased gradually within 24 h, and there was a threshold for uranium endocytosis, while the fraction of uranium binding to cell surface was low (< 0.2%). Over 40% of the endocytic uranium would be exocytosed within 1 h. Uranium could form needle-like precipitates in both intracellular and extracellular areas after uranium exposure. Conclusion After uranium exposure, cells show decreased viability, cell cycle arrest, and cell apoptosis. The process of endocytosis and exocytosis of soluble uranium is very rapid. HK-2 cells can convert soluble uranium into non-toxic precipitates.

Research progress in promotion of peripheral nerve regeneration by regulating macrophages / 中华显微外科杂志

This article reviews the research progress in promotion of peripheral nerve regeneration by regulating macrophages, a new idea for the research and treatment of peripheral nerve injury. The Trauma Center of The First People's Hospital Affiliated to Shanghai Jiao Tong University reviewed the relevant literatures in the regulation of macrophages on peripheral nerve regeneration at home and abroad, from 2013 to 2021, were reviewed and analysed. Of the study from 2013 to 2021, autologous nerve transfer was the main option in the treatment of peripheral nerve injury, but it has many setbacks such as insufficient donor, new nerve injury and local neuroma. Modulating macrophage-related function can effectively improve the prognosis of nerve injury. In recent years, the regulation of macrophages in the treatment of nerve injury is mainly through the mechanism of M1 macrophages polarisation to M2 macrophages, increase of phagocytosis, change of the phenotype of macrophages, and so on. By studying the characteristics of macrophages and regulating the function and phenotype of macrophages, it would provide a new idea and important research direction in the treatment of peripheral nerve injury.

The upregulated intestinal folate transporters direct the uptake of ligand-modified nanoparticles for enhanced oral insulin delivery

Transporters are traditionally considered to transport small molecules rather than large-sized nanoparticles due to their small pores. In this study, we demonstrate that the upregulated intestinal transporter (PCFT), which reaches a maximum of 12.3-fold expression in the intestinal epithelial cells of diabetic rats, mediates the uptake of the folic acid-grafted nanoparticles (FNP). Specifically, the upregulated PCFT could exert its function to mediate the endocytosis of FNP and efficiently stimulate the traverse of FNP across enterocytes by the lysosome-evading pathway, Golgi-targeting pathway and basolateral exocytosis, featuring a high oral insulin bioavailability of 14.4% in the diabetic rats. Conversely, in cells with relatively low PCFT expression, the positive surface charge contributes to the cellular uptake of FNP, and FNP are mainly degraded in the lysosomes. Overall, we emphasize that the upregulated intestinal transporters could direct the uptake of ligand-modified nanoparticles by mediating the endocytosis and intracellular trafficking of ligand-modified nanoparticles via the transporter-mediated pathway. This study may also theoretically provide insightful guidelines for the rational design of transporter-targeted nanoparticles to achieve efficient drug delivery in diverse diseases.

Effect of AMPA receptor endocytosis inhibitor GluA2-3Y on cognitive function and postsynaptic protein expression in chronic cerebral hypoperfusion rats / 中华行为医学与脑科学杂志

Objective:To investigate the effect of GluA2-3Y which is an inhibitor of AMPA(α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid) receptor internalization on cognitive function and hippocampal postsynaptic protein expression in rats with chronic cerebral hypoperfusion.Methods:Forty-eight adult male SD rats were randomly divided into Sham group, 2VO group, high-dose GluA2-3Y group and low-dose GluA2-3Y group according to random number table, with 12 rats in each group.The chronic cerebral hypoperfusion model of rat was established by two vessel occlusion (2VO) while the Sham operation was performed in rats of Sham group.The rats in high dose GluA2-3Y group and low dose GluA2-3Y group were intraperitoneal injected with 3 μmol/kg and 0.03 μmol/kg GluA2-3Y respectively once a day for 2 weeks. Rats in 2VO group and Sham group were intraperitoneally injected with control peptide. Morris water maze test and new object recognition test were performed to evaluate the learning and memory ability of rats, and Western blot was used to evaluate the expression of Akt1、GSK3β、p-GSK3β、GluA2 and PSD-95 in rat hippocampus. The expressions of GluA2 and PSD-95 in rat hippocampus were evaluated by immunofluorescence. SPSS 23.0 software was used for data analysis. The comparison between multiple groups was analyzed by one-way ANOVA and repeated measurement ANOVA was used to analyze Morris water maze results. And independent-samples t-test was used for pairwise comparisons. Results:(1)In Morris water maze trials, the results of repeated measurement ANOVA showed that the interaction between group and time of escape latency of rats in each group was not significant ( F=0.79, P>0.05), and the group main effect and time main effect were significant ( F=24.44, 40.42, both P<0.05). On the 5th day of navigation trials, the escape latency of rats in 2VO group was longer than that in sham group ( t=5.87, P<0.05). The escape latency of rats in low dose GluA2-3Y group and high dose GluA2-3Y group were significantly shorter than that in 2VO group ( t=2.20, 3.41, both P<0.05), but there was no significant difference between low dose GluA2-3Y group and high dose GluA2-3Y group ( t=1.37, P>0.05). The target quadrant residence time and resolution coefficient ((14.57±1.40)s, (0.15±0.10)) in 2VO group were significantly lower than those in Sham group ((23.71±2.57)s, (0.40±0.06)) ( t=3.23, 2.24, both P<0.05), while the target quadrant residence time in high dose GluA2-3Y group ((20.19±1.53)s) and low dose GluA2-3Y group ((20.31±2.06)s) were longer than that in 2VO group( t=2.71, 2.35, both P<0.05). The discrimination coefficients in high dose GluA2-3Y group (0.47±0.10) and low dose GluA2-3Y group (0.59±0.06) were higher than that of 2VO group ( t=2.21, 3.94, both P<0.05). (2)The Western blot results showed that the expression of PSD-95 and GluA2 in hippocampus of rats in 2VO group were significantly lower than those in Sham group ( t=2.31, 2.20, both P<0.05), and the expression of PSD-95 in high dose GluA2-3Y group (1.026±0.056) was significantly higher than that in 2VO group ((0.760±0.061), t=2.49, P<0.05), while there was no significant difference between low-dose GluA2-3Y group and 2VO group( t=0.96, P>0.05). The expression of GluA2 in low-dose GluA2-3Y group was higher than that in 2VO Group ((1.130±0.087), (0.766±0.080), t=2.37, P<0.05), but there was no significant difference between high-dose GluA2-3Y group and 2VO group( t=1.06, P>0.05). (3) Immunofluorescence showed that compared with Sham group, the expression of PSD-95 and GluA2 in 2VO group decreased ( t=4.23, 2.57, P<0.05). Compared with 2VO group, the expression of PSD-95 and GluA2 in high dose GluA2-3Y group and low dose GluA2-3Y group increased significantly, and the differences were statistically significant (PSD-95: (7.757±0.578), (12.057±0.578), t=3.14, 6.96, both P<0.05; (9.721±0.950), (16.610±0.950), t=4.56, 9.34, both P<0.05). (4) The results of Western blot showed that the expression GSK3β in hippocampus of rats in each group were not statistically different( F=2.03, P>0.05). There were significant differences in the expression of Akt1, p-GSK3β and the percentage of p-GSK3β/GSK3β in hippocampus of rats in each group ( F=8.30, 4.76, 3.57, all P<0.05). Compared with Sham group, the levels of Akt1, p-GSK3β and the percentage of p-GSK3β/GSK3β in 2VO group were significantly lower ( t=3.00, 2.81, 3.17, all P<0.05). Compared with 2VO group, the levels of Akt1, p-GSK3β and p-GSK3β/GSK3β percentage in low dose GluA2-3Y group and high-dose GluA2-3Y group were significantly higher (Akt1: t=2.05, 5.20, both P<0.05; p-GSK3β: t=2.49, 4.15, both P<0.05; p-GSK3β/GSK3β percentage: t=2.30, 2.97, both P<0.05). Conclusion:GluA2-3Y, an AMPA receptor internalization inhibitor, can alleviate the cognitive impairment in rats with chronic cerebral hypoperfusion, which may be related to the increased expression of Akt1, p-GSK3β and postsynaptic proteins.

Effects of Rab7 gene up-regulation on renal fibrosis induced by unilateral ureteral obstruction

Rab7, an important member of the Rab family, is closely related to autophagy, endocytosis, apoptosis, and tumor suppression but few studies have described its association with renal fibrosis. In the early stage, our group studied the effects of Rab7 on production and degradation of extracellular matrix in hypoxic renal tubular epithelial cells. Because cell culture in vitro is different from the environment in vivo, it is urgent to understand the effects in vivo. In our current study, we established a renal fibrosis model in Rab7-knock-in mice (prepared by CRISPR/Cas9 technology) and wild type (WT) C57BL/6 mice using unilateral ureteral obstruction (UUO). Seven and 14 days after UUO, the expression of the Rab7 protein in WT mice, as well as the autophagic activity, renal function, and the degree of renal fibrosis in WT and Rab7-knock-in mice were examined by blood biochemical assay, hematoxylin-eosin and Masson staining, immunohistochemistry, and western blotting. We found that the Rab7 expression in WT mice increased over time. Furthermore, the autophagic activity constantly increased in both groups, although it was higher in the Rab7-knock-in mice than in the WT mice at the same time point. Seven days after UUO, the degree of renal fibrosis was milder in the Rab7-knock-in mice than in the WT mice, but it became more severe 14 days after surgery. Similar results were found for renal function. Therefore, Rab7 suppressed renal fibrosis in mice initially, but eventually it aggravated fibrosis with the activation of autophagy.

The screening and identification of internalized nanobody against EpCAM / 药学学报

Epithelial cell adhesion molecule (EpCAM) is a popular target for cancer therapy. In this research, 3 nanobodies with high specificity and endocytosis activity against EpCAM were developed, which provides a basis for the study of immunotoxin based on EpCAM. In our preliminary experiments, we have immunized a camel with EpCAM-Fc antigen and constructed a high-quality phage display library. Seventeen nanobodies with different complementarity determining region (CDR) 3 sequences have been screened after 3 rounds of biopanning by phage display technology. The animal procedures were approved by the Institutional Animal Care and Use Committee (IACUC) of Fudan University School of Pharmacy. After purification, 7 nanobodies showed high cell binding activity by fluorescent activated cell sorting (FACS) identification. Furthermore, 3 nanobodies presented high endocytosis activity based on FACS and laser confocal microscopy, which also showed high affinity to EpCAM measured by ForteBio. According to this study, we aimed to provide a novel alternative approach to the EpCAM-targeted therapy and to provide guidance for the study of nanobody based immunotoxins for other targets.

Electroacupuncture intervention relieves pain possibly by promoting MOR endocytosis in locus coeruleus in bone cancer pain rats with morphine tolerance / 针刺研究

OBJECTIVE: To observe the effect of electroacupuncture (EA) on pain behavior and expression of µ-opioid receptor (MOR) and Rab5 (an important protein molecule for internalization of MOR) in the locus coeruleus (LC) region in bone cancer pain (BCP) rats with morphine tolerance (MT), so as to explore its mechanisms underlying improvement of BCP and MT. METHODS: The present study included two parts. In the first part, 23 female SD rats were randomized into sham BCP (n＝6), BCP (n＝9) and BCP＋MT (n＝8) groups, and in the second part, 61 female SD rats were randomized into 5 groups: sham BCP (n＝11), BCP (n＝11), BCP＋MT (n＝13), BCP＋MT＋EA (n＝13) and BCP＋MT＋sham EA (n＝13). The BCP morphine tolerance (BCP＋MT) model was established by injection of 10 µL of human Walker 256 breast cancer cells (MRMT-1 breast cancer cells, 1 x104 cells/µL) into the bone marrow cavity at the upper part of the left tibia and intraperitoneal injection of morphine hydrochloride (10 mg/kg, once per 12 h, for 11 successive days). On day 21 after inoculation, EA (2 Hz/100 Hz, 0.5－1.5 mA, increasing 0.5 mA every 10 min) was began to applied to bilateral "Zusanli" (ST30) and "Kunlun" (BL60) immediately after the first intraperitoneal injection of morphine. The treatment was performed for 30 min every time, once daily for 7 successive days. The paw withdrawal threshold (PWT) was detected before and 10, 11, 21, 22, 24, 26 and 28 days after inoculation. The immunoactivity of MOR and Rab5 proteins in the LC region was detected by immunofluorescence histochemistry. RESULTS: In the first part of the study, at the 10th day after inoculation of cancer cells, the PWT of the BCP and BCP＋MT groups was significantly lower than that of the sham BCP group (P0.05) but significantly lower than that of the sham BCP group (P0.05). CONCLUSION: EA intervention can relieve pain and MT in bone cancer pain rats with MT, which may be related to its effects in increasing MOR expression and promoting endocytosis of MOR in LC region.

Role of intracellular Ca2+ in regulating NHE3 expression in Caco-2 cells during rotavirus infection / 中华微生物学和免疫学杂志

Objective To investigate the effects of rotavirus ( RV) on the expression and bioactiv-ity of Na+-H+ exchanger 3 ( NHE3 ) in Caco-2 cells and the possible regulatory mechanism. Methods Caco-2 cells expressing NHE3 were constructed and divided into four groups as follows: control ( CTL ) group, RV group, BAPTA-AM ( a Ca2+ chelator) group and BAPTA-AM+RV group. Na+-H+ exchanger ac-tivity and NHE3 expression on cell surface were determined using BCECF-AM and biotinylation assay, re-spectively. Expression of Cdc42 at protein level was measured by Western blot. Results Compared with the control group, RV infection significantly decreased the activity of NHE3 and its expression on cell surface. BATPA-AM antagonized the inhibitory effects on NHE3. Moreover, the expression of Cdc42 at protein level was increased following RV infection, which was also antagonized by BATPA-AM. Conclusions Intracellu-lar Ca2+-mediated Cdc42-dependent endocytosis pathway might be involved in regulating the expression and bioactivity of NHE3 during RV infection.

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.

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.

Cdc42-dependent endocytosis pathway in the regulation of Na+/H+exchanger 3 (NHE3) expression on rotavirus-infected Caco-2 cells / 中华微生物学和免疫学杂志

Objective To observe the effects and regulatory mechanism of rotavirus infection on the expression and bioactivity of Na+/H+exchanger 3 (NHE3) on Caco-2 cells. Methods A cell model of Caco-2 cells expressing NHE3 was constructed. Four groups were set up,which were control(CTL) group, rotavirus(RV) infection group, Cdc42 inhibitor (Pirl-1) group and Pirl-1+RV group. Bioactivity and ex-pression of NHE3 on the surface of Caco-2 cells were determined by BCECF-AM and biotinylation method, respectively. Expression of Cdc42 protein was measured by Western blot. Co-immunoprecipitation was per-formed to detect the interaction between NHE3 and Cdc42. Results Compared with the CTL group,RV in-fection significantly inhibited the bioactivity and expression of NHE3 on Caco-2 cells. These inhibitory effects were antagonized by Pirl-1. Moreover,RV infection enhanced the expression of Cdc42 protein and promoted the interaction between NHE3 and Cdc42, which were also antagonized by Pirl-1. Conclusion RV infec-tion might regulate the expression and bioactivity of NHE3 through Cdc42-dependent endocytosis pathway.

Progress in synaptic mechanism in epileptogenesis / 中南大学学报(医学版)

Recurrent seizures lead to abnormal expression of synaptic proteins,reorganization of synapse and formation of abnormal neuron network.Recently,it is identified that the synaptic proteins are involved in epileptogenesis.The abnormal expression of several synaptic regulatory proteins and postsynaptic membrane receptor proteins may result in epilepsy.The ion channels usually are the action target of most antiepileptic drugs.However,carbamazepine and zonisamide may interact with syntaxin and/or soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex to exert its function of anti-epilepsy.The synaptic vesicle protein 2A is the action target for new anti-epileptic drugs,including levetiracetam,brivaracetam and seletracetam.

Caveolin-1 involvement of albumin in improving blood-brain barrier permeability after subarachnoid hemorrhage / 国际脑血管病杂志

Objective To investigate the effect of human serum albumin (Alb) on the permeability of blood-brain barrier (BBB) after subarachnoid hemorrhage (SAH) and the pathways for Alb uptake in endothelial cells.Methods Mouse brain endothelial cells (bEnd.3) were cultured in the Transwell chamber was used to induce a BBB model.A SAH in vitro model was induced by adding 10 μmol/L oxyhemoglobin into the culture medium.The cells were divided into 3 groups:control group,SAH group,and Alb group (10 mg/ml).Transendothelial electric resistance (TEER) was used to detect the permeability of BBB.A confocal microscope was used to observe whether the fluorescent labeled Alb could be uptaken by bEnd.3cells.Immunoprecipitation was used to detect whether Alb could interact with the cells of caveolin 1 (Cav-1).According to the principle of siRNA,Cav-1 siRNA was transfected into bEnd.3 cells to inhibit the expression of Cav-1.Western blot analysis was used to detect whether bEnd.3 cells could uptake Alb.TEER was used to detect the permeability of BBB.Results Compared with the SAH group,the TEER value of the Alb group increased significantly (P =0.011).Alb was uptaken by bEnd.3 cells and interacted with Cav-1 in bEnd.3 cells.Cav-1 siRNA transfection could significantly inhibit the expression of Cav-1 in bEnd.3cells and reduce the uptake ability of Alb by cells (P=0.025),resulting in a significant decrease in the protective effect of Alb on BBB (P ＜ 0.001).Conclusion Cav-1 may be uptaken by endothelial cells under the participation of Cav-1 and improve the permeability of BBB after SAH.

Effect of rotavirus infection on regulating the expression of Na+-H+ exchanger 3 in Caco-2 cells via clathrin dependent endocytosis pathway / 中国感染与化疗杂志

Objective To observe the effect of rotavirus (RV) infection on expression level and bioactivity of Na+-H+ exchanger 3 (NHE3) in Caco-2 cells. Methods Model of NHE3-expressing Caco-2 cells was constructed and studied in terms of intervention: control, RV, clathrin antagonist chlorpromazine (CPZ), and CPZ + RV. NHE3 activity and NHE3 protein amount on cell surface were determined by BCECF-AM and biotinylation, respectively. Expression level of clathrin was assayed by Western blot. Results Compared with control group, NHE3 activity and NHE3 surface protein level significantly decreased when the cells were treated with RV. These effects could not be completely cancelled by clathrin antagonist CPZ. Moreover, RV treatment could increase cellular protein level of clathrin, which was cancelled by CPZ. Conclusions The effect of RV infection on NHE3 expression level and biological activity may be related to clathrin-dependent endocytosis pathway, and may be also affected by other endocytosis pathways.

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.