Expression Of Rab7 Research Articles

MiR-409-3p inhibits the proliferation and migration of human ovarian cancer cells by targeting Rab10

Ovarian cancer is a leading cause of gynecological cancer-related mortality. It has been reported that miR-409-3p is involved in the proliferation and migration of cancer cells. However, the role of miR-409-3p in ovarian cancer has not been well studied. The present study aimed to investigate the functional role of miR-409-3p in the pathogenesis of ovarian cancer, and its potential mechanism. It was found that the expression levels of miR-409-3p in 6 ovarian cancer tissues were upregulated. Through proliferation, migration and colony formation assays, it was revealed that overexpression of miR-409-3p inhibited the proliferation and migration of ovarian cancer cells. It was predicted from bioinformatics assays that the complementary binding sites were within miR-409-3p and Rab10. It was also demonstrated that the downregulation of the expression of Rab10 reversed the miR-409-3p downregulation-induced abnormal proliferation of ovarian cancer cells. These results suggest that miR-409-3p expression can be used as a predictive marker for the prognosis of ovarian cancer. Thus, the miR-409-3p/Rab10 axis may be a novel therapeutic target for ovarian cancer.

Rab GTPase Mediating Regulation of NALP3 in Colorectal Cancer.

The NALP3 inflammasome signaling contributes to inflammation within tumor tissues. This inflammation may be promoted by the vesicle trafficking of inflammasome components and cytokines. Rab5, Rab7 and Rab11 regulate vesicle trafficking. However, the role of these proteins in the regulation of inflammasomes remains largely unknown. To elucidate the role of these Rab proteins in inflammasome regulation, HCT-116, a colorectal cancer (CRC) cell line expressing pDsRed-Rab5 wild type (WT), pDsRed-Rab5 dominant-negative (DN), pDsRed-Rab7 WT, pDsRed-Rab7 DN, pDsRed-Rab11 WT and pDsRed-Rab11 DN were treated with lipopolysaccharide (LPS)/nigericin. Inflammasome activation was analyzed by measuring the mRNA expression of NLRP3, Pro-CASP1, RAB39A and Pro-IL-1β, conducting immunofluorescence imaging and western blotting of caspase-1 and analysing the secretion levels of IL-1β using enzyme-linked immunosorbent assay (ELISA). The effects of Rabs on cytokine release were evaluated using MILLIPLEX MAP Human Cytokine/Chemokine Magnetic Bead Panel-Premixed 41 Plex. The findings showed that LPS/nigericin-treated cells expressing Rab5-WT indicated increased NALP3 expression and secretion of the IL-1β as compared to Rab5-DN cells. Caspase-1 was localized in the nucleus and cytosol of Rab5-WT cells but was localized in the cytosol in Rab5-DN cells. There were no any effects of Rab7 and Rab11 expression on the regulation of inflammasomes. Our results suggest that Rab5 may be a potential target for the regulation of NALP3 in the treatment of the CRC inflammation.

Metformin Increases Exosome Biogenesis and Secretion in U87 MG Human Glioblastoma Cells: A Possible Mechanism of Therapeutic Resistance

Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor. Metformin, an anti-diabetic drug, can suppress tumor cells. Exosomes from GBM cells contribute to intercellular communication, tumor aggressiveness, and therapeutic resistance. We studied the effect of metformin on the exosomal secretory pathway in U87MGcells. Cell survival against metformin was investigated using MTT assay. Expression of miRNA-21, miRNA-155, and miRNA-182, as well as the genes involved in exosome biogenesis and secretion such as Rab27a, Rab27b, Rab11, CD63, and Alix were calculated by real time-PCR. The expression of CD63 protein was analyzed by western blotting, while the subcellular distribution of CD63 protein was monitored by flow cytometry. Exosomes were characterized by transmission and scanning electron microscopes, and flow cytometry. Amount of exosomes was assayed using acetylcholinesterase activity assay and ELISA. The expression of autophagic markers LC3 and P62 were assessed using ELISA. Data showed that metformin decreased cell survival and expression of miRNA-21, miRNA-155, and miRNA-182 (p <0.05). Expression of Rab27a, Rab27b, Rab11, CD63, and Alix as well as protein level of CD63 up-regulated in treated cells (p <0.05). Concurrently, flow cytometry analysis showed that surface CD63/total CD63 ratio was increased in treated cells (p <0.05). We found that acetylcholinesterase activity and CD63 protein of exosomes from treated cells increased (p <0.05). The expression of LC3 and P62 was not affected by metformin (p >0.05). Data indicates metformin could promote exosome biogenesis and secretion in U87MGcells, proposing the therapeutic response against metformin.

Increased RAB31 Expression in Cancer-Associated Fibroblasts Promotes Colon Cancer Progression Through HGF-MET Signaling.

RAB family proteins participate in the dynamic regulation of cellular membrane compartments and are dysregulated in a variety of tumor types, which may alter the biological properties of cancer cells such as proliferation, migration, and invasion. In our previous study, we found that Ras-related protein Rab-31 (RAB31) expression was increased in late-stage colorectal cancer (CRC). The role of RAB31 has never been investigated in CRC. In this study, we found that expression of RAB31 in the tumor stroma but not cancer cells of colon cancer predicted poor survival. RAB31 can be detected in primary cancer-associated fibroblasts (CAFs) and paired normal fibroblasts. Conditioned medium (CM) from RAB31 overexpressing CAFs significantly promoted migration of colon cancer cell lines in vitro and in vivo. This process may be mediated by paracrine action of hepatocyte growth factor (HGF), which was increased in the CM of RAB31-overexpressing CAFs. Blockade of HGF/MET signaling by drug inhibition, knockdown of mesenchymal to epithelial transition factor (MET) in RKO, or antibody neutralization of HGF abolished migration of RKO cells mediated by RAB31 expression in CAFs. We propose that in colon cancer, increased RAB31 expression in CAFs may contribute to tumor progression by regulating the secretion of HGF in the tumor stroma.

IKKβ activation promotes amphisome formation and extracellular vesicle secretion in tumor cells

Intracellular organelle cross-talk is a new and important research area. Under stress conditions, the coordinated action of the autophagy and endosomal systems in tumor cells is essential for maintaining cellular homeostasis and survival. The activation of the IκB kinase (IKK) complex is also involved in the regulation of stress and homeostasis in tumor cells. Here, we try to explore the effects of constitutively active IKKβ subunits (CA-IKKβ) on autophagy and endosomal system interactions. We confirm that CA-IKKβ induces accumulation of autophagosomes and their fusion with MVBs to form amphisomes in cancer cells, and also drives the release of EVs containing autophagy components through an amphisome-dependent mechanism. We further demonstrate that CA-IKKβ inhibits the expression of RAB7, thereby weakening the lysosomal-dependent degradation pathway. CA-IKKβ also induces phosphorylation of SNAP23 at Ser95 instead of Ser110, which further promotes amphisome-plasma membrane fusion and sEV secretion. These results indicate that CA-IKKβ drives the formation and transport of amphisomes, thereby regulating tumor cell homeostasis, which may illuminate a special survival mechanism in tumor cells under stress.

RAB31 is targeted by miR-26b and serves a role in the promotion of osteosarcoma.

Ras-related protein Rab-31 (RAB31), a small guanosine 5'-triphosphate-binding protein, is a member of the Rab family and has been demonstrated to serve an oncogenic role in several common types of human cancer. However, the function of RAB31 in osteosarcoma (OS) has not been previously studied. The present study identified that the expression levels of RAB31 were significantly higher in OS tissue samples compared with matched adjacent non-tumor tissue samples, and high RAB31 expression was associated with malignant progression and a poor prognosis for patients with OS. Furthermore, it was identified that the expression levels of RAB31 were increased in OS cell lines compared with normal osteoblast cells. Silencing of RAB31 expression significantly inhibited OS cell proliferation, cell cycle progression, migration and invasion, and significantly increased the rate of cell apoptosis. In addition, the present study used a luciferase reporter assay to demonstrate that RAB31 was a direct target gene of microRNA-26b (miR-26b), which is a known tumor suppressor in OS. The expression levels of RAB31 were negatively associated with miR-26b expression in OS cells. Finally, miR-26b was demonstrated to be significantly decreased in OS tissues compared with adjacent non-tumor tissues, and an inverse correlation was observed between the expression levels of RAB31 and miR-26b in OS tissues. In summary, to the best of our knowledge, the present study is the first to report that RAB31 is a target gene of miR-26b, and silencing of RAB31 may inhibit OS growth and progression.

RAB25 confers resistance to chemotherapy by altering mitochondrial apoptosis signaling in ovarian cancer cells.

Ovarian cancer remains one of the most frequent causes of cancer-related death in women. Many patients with ovarian cancer suffer from de novo or acquired resistance to chemotherapy. Here, we report that RAB25 suppresses chemotherapy-induced mitochondrial apoptosis signaling in ovarian cancer cell lines and primary ovarian cancer cells. RAB25 blocks chemotherapy-induced apoptosis upstream of mitochondrial outer membrane permeabilization by either increasing antiapoptotic BCL-2 proteins or decreasing proapoptotic BCL-2 proteins. In particular, BAX expression negatively correlates with RAB25 expression in ovarian cancer cells. BH3 profiling assays corroborated that RAB25 decreases mitochondrial cell death priming. Suppressing RAB25 by means of RNAi or RFP14 inhibitory hydrocarbon-stapled peptide sensitizes ovarian cancer cells to chemotherapy as well as RAB25-mediated proliferation, invasion and migration. Our data suggest that RAB25 is a potential therapeutic target for ovarian cancer.

UNC0321 inhibits high glucose induced apoptosis in HUVEC by targeting Rab4

The vascular complications in heart, brain, kidney and retina are the most common chronic complications of diabetes mellitus (DM). At present, it has become a research hotspot to regulate the abnormal apoptosis of vascular endothelial cells for DM treatment. UNC0321 is a high affinity GPCRs inhibitor, and has potential practical value in chromatin remodeling. In this study, we treated HUVEC with UNC0321 in vitro, and found that UNC0321 inhibit the level of Cleaved-Caspase3 and Bax, thus inhibiting the apoptosis caused by high glucose. In addition, UNC0321 also promoted cell proliferation and migration by activating Akt / mTOR pathway. The transcriptome changes of HUVEC cells cultured with high glucose with or without the treatment of UNC0321 were analysis using sequencing. It was found that Rab4 expression was significantly inhibited after UNC0321 treatment. Subsequently, we overexpressed Rab4 in HUVEC cells cultured with high glucose, and found that overexpression of Rab4 promoted the apoptosis, and inhibited cell proliferation and migration. At the same time, after overexpression of Rab4 in HUVEC cells treated with UNC0321, the number of apoptosis was significantly increased, cell proliferation and migration were inhibited, and the activity of Akt / mTOR pathway decreased. These data suggested that overexpression of Rab4 effectively blocked the inhibition of apoptosis and the increase of cell proliferation induced by UNC0321. In conclusion, we found that UNC0321 inhibits the apoptosis of HUVEC cells caused by high glucose through inhibiting Rab4 expression, providing new potential drugs and targets for the treatment of diabetic vascular complications.

Abstract 2601: Expression and clinicopathological association of RABs in pancreatic cancer

Abstract Rab proteins form the largest subfamily of small GTPases and play an indispensable role in the regulation of vesicle trafficking. They control a wide variety of endocytic, transcytic and exocytic transport pathways and thus play important roles in cellular growth and behavior. Altered expression and functions of Rab proteins have been reported in various malignancies and implicated in tumorigenic processes. Pancreatic cancer (PC) is a highly lethal malignancy and molecular mechanisms associated with its pathobiology are relatively less understood. Here we mined The Cancer Genome Atlas (TCGA) Database for differential expression and clinicopathological association of RAB genes in pancreatic cancer. Out of the 62 RAB genes analyzed, 5 (RAB3A, RAB26, RAB25, RAB21, and RAB22A) were found to have significant upregulation in cancer, while 5 (RAB6B, RAB8B, RABL2A, RABL2B and RAB32) exhibited significant downregulation. Racially disparate expression was also reported for some RABs. RAB3A and RAB26 had significantly higher and lower expression, respectively, in African American (AA) and Asian PC as compared to Caucasian Americans (CA) PC, whereas RAB25 was significantly higher in Asian PC than CA PC. No clear trend of altered expression was observed with increasing stage and grade, although stage- and grade-specific differences were recorded for some RABs. RAB21, RAB22A, and RAB8B showed significantly higher expression in PC from middle-aged patients (41-60 years) compared to older age groups, but no gender-associated differential expression was observed. PC from occasional drinkers had significantly higher expression of RAB21 compared to daily or weekly drinker, whereas RAB25 expression was significantly higher in social drinkers, compared to occasional ones. Expression of RABL2A was significantly reduced in PC of diabetic patients whereas RAB26 was significantly down in pancreatitis patients. Most importantly, a significant association of high expression of RAB21, RAB22A and RAB25, and low expression of RAB6B, RABL2A, and RABL2B was observed with poorer survival of PC patients. Together, our study is suggestive of potential diagnostic and prognostic significance of RABs in PC and warrants further investigations to define their functional and mechanistic significance. Citation Format: Shashi Anand, Haseeb Zubair, Mohammad Aslam Khan, Seema Singh, Ajay P. Singh. Expression and clinicopathological association of RABs in pancreatic cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2601.

Abstract 1520: RAB31 triggers oxaliplatin resistance in colorectal cancer via epithelial-mesenchymal transition

Abstract Colorectal tumorigenesis during Epithelial-Mesenchymal transition (EMT) is associated with cancer metastasis and drug resistance. The small G-proteins family has been implicated in the regulation of cell cytoskeleton, cell movement, and vesicle transport. Small G-proteins family is divided into five main families. The Rab protein family is a member of the Ras superfamily of small G-proteins. We analyzed all probes of the Rab family members from microarray datasets and RNA-sequencing. We further calculated the EMT scores by using an algorithm. Our results showed that the RAB31 expression levels of the three probes are positively correlated with EMT score (Pearson rho=0.72, 0.71 and 0.68, respectively). Compared with other family members, RAB31 had most significantly value in colorectal cancer cell lines. We established several two-way model with cDNA and shRNAs of RAB31, respectively. Furthermore, we observed that the expression of epithelial type marker CDH1 was inhibited, and mesenchymal type markers SNAI1 and SNAI2 were upregulated in RAB31 overexpression models. Moreover, we found that the protein level of RAB31 was correlated with several clinicopathological parameters (N status, M status) and disease-free survival in tissue arrays through immunohistochemistry staining. According to The Cancer Genome Atlas Program (TCGA) and online meta-database, high RNA level of RAB31 was consistent in colorectal cancer (HR=1.38, n=466 and HR=1.29, n=482) and correlated with poor prognosis of patients. In addition, we identified that RAB31 may associated with IC50 of oxaliplatin and EGFR trafficking. We concluded that RAB31 regulates the sensitivity of oxaliplatin, an additional chemotherapy strategy and an independent prognostic factor for colorectal cancer. Citation Format: Chi-Long Chen, Yu-Chan Chang, Michael Hsiao. RAB31 triggers oxaliplatin resistance in colorectal cancer via epithelial-mesenchymal transition [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1520.

Comprehensive Analysis of Expression, Clinicopathological Association and Potential Prognostic Significance of RABs in Pancreatic Cancer.

RAB proteins (RABs) represent the largest subfamily of Ras-like small GTPases that regulate a wide variety of endosomal membrane transport pathways. Their aberrant expression has been demonstrated in various malignancies and implicated in pathogenesis. Using The Cancer Genome Atlas (TCGA) database, we analyzed the differential expression and clinicopathological association of RAB genes in pancreatic ductal adenocarcinoma (PDAC). Of the 62 RAB genes analyzed, five (RAB3A, RAB26, RAB25, RAB21, and RAB22A) exhibited statistically significant upregulation, while five (RAB6B, RAB8B, RABL2A, RABL2B, and RAB32) were downregulated in PDAC as compared to the normal pancreas. Racially disparate expression was also reported for RAB3A, RAB25, and RAB26. However, no clear trend of altered expression was observed with increasing stage and grade, age, and gender of the patients. PDAC from occasional drinkers had significantly higher expression of RAB21 compared to daily or weekly drinkers, whereas RAB25 expression was significantly higher in social drinkers, compared to occasional ones. The expression of RABL2A was significantly reduced in PDAC from diabetic patients, whereas RAB26 was significantly lower in pancreatitis patients. More importantly, a significant association of high expression of RAB21, RAB22A, and RAB25, and low expression of RAB6B, RABL2A, and RABL2B was observed with poorer survival of PC patients. Together, our study suggests potential diagnostic and prognostic significance of RABs in PDAC, warranting further investigations to define their functional and mechanistic significance.

LINC00441 promotes cervical cancer progression by modulating miR-450b-5p/RAB10 axis

BackgroundAs one of the most common gynaecological malignant tumors, cervical cancer (CC) has become an important public health issue. Emerging evidence has revealed long non-coding RNAs (lncRNAs) are crucial regulators of biological functions in cancers, including CC. And the oncogenic role of LINC00441 has been verified in hepatocellular carcinoma (HCC). But the molecular mechanism and biological functions of LINC00441 in CC remain unknown.MethodsqRT-PCR analysis detected the expression of genes in CC tissues or cells. CCK-8, colony formation, flow cytometry, transwell, western blot assays as well as animal studies were conducted to analyze the function of LINC00441 in CC. Luciferase reporter, RIP and RNA pull down assays were applied to verify the binding relations among the indicated genes.ResultsLINC00441 was upregulated in CC tissues and cells. Further, LINC00441 depletion repressed cell proliferation and motility in vitro as well as tumor growth in vivo. LINC00441 could sponge miR-450b-5p to upregulate RAB10 expression. Finally, miR-450b-5p inhibitor or RAB10 upregulation counteracted LINC00441 knockdown-mediated function on the development of CC.ConclusionsLINC00441 drives CC progression by targeting miR-450b-5p/RAB10 axis, which might provide new idea for researching CC-related molecular mechanism.

Upregulation of Rab31 is associated with poor prognosis and promotes colorectal carcinoma proliferation via the mTOR/p70S6K/Cyclin D1 signalling pathway

AimsRab31, a Rab5 subfamily member, has emerged as a modulator of membrane trafficking. Our study serves to clarify the role and mechanism of Rab31 in colorectal carcinoma (CRC) pathogenesis. Materials and methodsThe differential expression of Rab31 was examined in paired normal and cancerous colonic tissues by quantitative PCR, western blot and immunochemistry. The prognostic significance of Rab31 was analysed by univariate and multivariate survival analyses. We also investigated the effects of Rab31 on tumour growth in vitro. Key findingsWe observed that Rab31, which is related to histological differentiation in CRC, was markedly overexpressed in CRC cells. Moreover, patients who showed higher Rab31 levels had a shortened survival period relative to those with low Rab31 levels. Rab31 knockdown significantly downregulated cyclin D1, p-mTOR, and p-p70S6K expression. Moreover, the expression of Rab31-induced p-p70S6K was almost inhibited by rapamycin, a well-established inhibitor of mTOR. Similarly, rapamycin also significantly decreased the stimulatory effect of Rab31 on the expression of cyclin D1. SignificanceThese findings suggested that Rab31 enhanced proliferation, promoted cell cycle progression, and inhibited apoptosis of colorectal carcinoma cells through the mTOR pathway.

FCHSD2 controls oncogenic ERK1/2 signaling outcome by regulating endocytic trafficking

The evolution of transformed cancer cells into metastatic tumors is, in part, driven by altered intracellular signaling downstream of receptor tyrosine kinases (RTKs). The surface levels and activity of RTKs are governed mainly through clathrin-mediated endocytosis (CME), endosomal recycling, or degradation. In turn, oncogenic signaling downstream of RTKs can reciprocally regulate endocytic trafficking by creating feedback loops in cells to enhance tumor progression. We previously showed that FCH/F-BAR and Double SH3 Domain-Containing Protein (FCHSD2) has a cancer-cell specific function in regulating CME in non-small-cell lung cancer (NSCLC) cells. Here, we report that FCHSD2 loss impacts recycling of the RTKs, epidermal growth factor receptor (EGFR) and proto-oncogene c-Met (MET), and shunts their trafficking into late endosomes and lysosomal degradation. Notably, FCHSD2 depletion results in the nuclear translocation of active extracellular signal-regulated kinase 1 and 2 (ERK1/2), leading to enhanced transcription and up-regulation of EGFR and MET. The small GTPase, Ras-related protein Rab-7A (Rab7), is essential for the FCHSD2 depletion-induced effects. Correspondingly, FCHSD2 loss correlates to higher tumor grades of NSCLC. Clinically, NSCLC patients expressing high FCHSD2 exhibit elevated survival, whereas patients with high Rab7 expression display decreased survival rates. Our study provides new insight into the molecular nexus for crosstalk between oncogenic signaling and RTK trafficking that controls cancer progression.

Down-regulation of circ-PTN suppresses cell proliferation, invasion and glycolysis in glioma by regulating miR-432-5p/RAB10 axis

BackgroundCircular RNAs (circRNAs) are related to the carcinogenesis of cancers, including glioma. However, the role and mechanism of circRNA pleiotrophin (circ-PTN) remain largely unknown. MethodsGlioma tissues (n = 30) and normal tissues were obtained. Glioma cell lines LN229 and A172 were cultured for experiments in vitro. circ-PTN, microRNA-432-5p (miR-432-5p) and Ras-related protein Rab-10 (RAB10) levels were examined via quantitative reverse transcription polymerase chain reaction or western blot. Cell proliferation, invasion and glycolysis were examined via 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide, colony formation analysis, transwell invasion analysis, specific glucose, lactate or adenosine triphosphate assay kit and western blot. The relationship of miR-432-5p and circ-PTN or RAB10 was analyzed via dual-luciferase reporter analysis. The effect of circ-PTN on glioma development in vivo was explored by a murine xenograft model. Resultscirc-PTN expression was enhanced and miR-432-5p abundance was reduced in glioma tissues and cells. circ-PTN silence suppressed cell proliferation, invasion and glycolysis. circ-PTN regulated glioma development by directly sponging miR-432-5p. RAB10 was a target of miR-432-5p and miR-432-5p inhibited cell proliferation, invasion and glycolysis by targeting RAB10. circ-PTN could modulate RAB10 expression via miR-432-5p. circ-PTN knockdown reduced glioma cell xenograft tumor growth in vivo. Conclusioncirc-PTN knockdown repressed cell proliferation, invasion and glycolysis in glioma via modulating miR-432-5p and RAB10.

LncRNA PVT1 promotes exosome secretion through YKT6, RAB7, and VAMP3 in pancreatic cancer.

Pancreatic cancer (PC) is one of the deadliest cancers worldwide. Cancer cells secrete excessive numbers of exosomes that play essential roles in tumorigenesis. Long non-coding RNAs (lncRNAs) are essential non-coding RNAs for cancer progression. However, the role of lncRNA plasmacytoma variant translocation 1 (PVT1) in exosome secretion of PC remains to be comprehensively investigated. Thus, nanoparticle tracking analysis and transmission electron microscopy were performed to determine exosome secretion. Confocal microscopy, western blots, real-time PCR, immunofluorescence, pull-down and RNA immunoprecipitation assays, and rescue experiments were applied to investigate the mechanism underlying the role of PVT1 in exosome secretion. The results showed that PVT1 was upregulated in PC cells, along with increased levels of YKT6 v-SNARE homolog (YKT6), ras-related protein Rab-7 (RAB7), and vesicle-associated membrane protein 3 (VAMP3). Also, PVT1 promoted the transportation of multivesicular bodies (MVBs) towards the plasma membrane. In addition, PVT1 promoted the docking of MVBs by altering RAB7 expression and localization. Moreover, PVT1 promoted the fusion of MVBs with the plasma membrane through regulating YKT6 and VAMP3 colocalization and the palmitoylation of YKT6. Taken together, the results suggest that PVT1 promoted exosome secretion of PC cells and thus, can expand the understanding of PVT1 in tumor biology.

Rab5 regulates the proliferation, migration and invasion of glioma cells via cyclin E.

Glioma is the most common and lethal type of primary brain tumor, with a high mortality and recurrence rate. Rab5, which serves as a classic ontogenetic gene, is highly expressed in various types of tumor, including lung cancer, hepatocellular carcinoma and ovarian cancer. However, the exact role and the underlying mechanism of Rab5 in glioma remain unknown. Herein, the role of Rab5 in the tumorigenesis and metastasis of glioma cells was investigated. The upregulation of Rab5 in glioma tissues and cells was observed. The expression of Rab5 was positively associated with proliferation, migration and invasion of glioma cells. Moreover, Rab5 was involved in the cell cycle of glioma cells via the regulation of cyclin E. Data presented in the present study suggest Rab5 as a potential novel diagnostic and prognosis marker of glioma.

M206. EFFECTS OF RISPERIDONE ON THE MRNA EXPRESSION OF PROTEINS INVOLVED IN INTRACELLULAR TRAFFICKING IN THE MICE EXPOSED TO SOCIAL DEFEAT STRESS

BackgroundImpaired intracellular trafficking has been proposed as a new key pathophysiology for neuropsychiatric disorders. The present study investigated the effects of risperidone on the mRNA levels of various proteins involved in intracellular trafficking, and dopaminergic receptors [long and short forms of the dopamine receptor D2 (DRD2) and dopamine receptor D1 (DRD1)] in several key brain regions of wild type adult mice exposed to social defeat stress.MethodsC57BL/6J mice were subjected to chronic social defeat procedure for 10 consecutive days. The defeated mice were categorized into unsusceptible (UNS) and susceptible (SUS) groups based on performance in the social avoidance test. Animals were randomly divided into two groups, vehicle (VEH) and drug (DRUG) groups. Risperidone (RIS) was administered to the DRUG group at the dosage of 0.2 mg/kg, i.p. for 7days. After sacrifice and brain extraction, prefrontal cortex (PFC), hippocampus (HIP) and amygdala (AMY) were obtained. The mRNA levels of our target genes were measured by real time- PCR.ResultsIn the VEH group, mRNA expression levels of GASP1 and ARF6 were decreased in the PFC and HIP, and AMY of UNS mice respectively compared to control mice. The mRNA expression of Rab4 was rather increased in the PFC of UNS mice compared to control mice. In the DRUG group, only mRNA expression level of GASP1 was decreased in the PFC of UNS mice compared to control mice.DiscussionOur results indicate that social defeat stress induces changes in expression levels of GASP1, ARF6 and Rab4 in several key brain regions and these effects are blocked by risperidone. It may suggest that risperidone can prevent or treat an impairment of intracellular trafficking caused by defeat stress. As ARF6 is known to mediate recycling of D2 receptors and GASP-1 is involved in the lysosomal sorting of D2 receptor, our findings should be discussed with regard to the changes of mRNA expression levels of DRD2 and DRD1.

Efficient entry of budded virions of Autographa californica multiple nucleopolyhedrovirus into Spodoptera frugiperda cells is dependent on dynamin, Rab5, and Rab11

Autographa californica multiple nucleopolyhedrovirus (AcMNPV), a member of the Alphabaculovirus genus of the family Baculoviridae, is an enveloped double-stranded DNA virus. Budded virions (BVs) of AcMNPV enter host cells via clathrin-mediated endocytosis. However, the route of functional intracellular trafficking of AcMNPV BVs during entry is not well established. In the current study, we found that entering BVs were colocalized mainly with cellular Rab5 and Rab11. Expression of dominant-negative (DN) Rab5 and Rab11 or RNAi-mediated down regulation of these two cellular transcripts significantly reduced BVs entry into but not egress from Spodoptera frugiperda cells (Sf9), whereas similar treatments for Rab4 and Rab7 had no apparent effect on virus infection. Combined with data from RNAi knockdowns of dynamin, and dynasore inhibition assays, our results support a model in which AcMNPV BVs enter permissive host cells by clathrin-mediated endocytosis, followed by de-envelopment of BVs predominantly within early and maturing endosomes rather than within late endosomes. Additionally, Rab11 suppression studies suggest the Rab11-dependent recycling endosomal pathway is involved in virion entry.

Decrease of Rab11 prevents the correct dendritic arborization, synaptic plasticity and spatial memory formation

Emerging evidence shows that Rab11 recycling endosomes (REs Rab11) are essential for several neuronal processes, including the proper functioning of growth cones, synapse architecture regulation and neuronal migration. However, several aspects of REs Rab11 remain unclear, such as its sub-cellular distribution across neuronal development, contribution to dendritic tree organization and its consequences in memory formation. In this work we show a spatio-temporal correlation between the endogenous localization of REs Rab11 and developmental stage of neurons. Furthermore, Rab11-suppressed neurons showed an increase on dendritic branching (without altering total dendritic length) and misdistribution of dendritic proteins in cultured neurons. In addition, suppression of Rab11 in adult rat brains in vivo (by expressing shRab11 through lentiviral infection), showed a decrease on both the sensitivity to induce long-term potentiation and hippocampal-dependent memory acquisition. Taken together, our results suggest that REs Rab11 expression is required for a proper dendritic architecture and branching, controlling key aspects of synaptic plasticity and spatial memory formation.