SCAMP 3 is a novel regulator of endosomal morphology and composition

The endo-lysosomal system in Parkinson's disease: expanding the horizon

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease, and its prevalence is increasing with age. A wealth of genetic evidence indicates that the endo-lysosomal system is a major pathway driving PD pathogenesis with a growing number of genes encoding endo-lysosomal proteins identified as risk factors for PD, making it a promising target for therapeutic intervention. However, detailed knowledge and understanding of the molecular mechanisms linking these genes to the disease are available for only a handful of them (e.g. LRRK2, GBA1, VPS35). Taking on the challenge of studying poorly characterized genes and proteins can be daunting, due to the limited availability of tools and knowledge from previous literature. This review aims at providing a valuable source of molecular and cellular insights into the biology of lesser-studied PD-linked endo-lysosomal genes, to help and encourage researchers in filling the knowledge gap around these less popular genetic players. Specific endo-lysosomal pathways discussed range from endocytosis, sorting, and vesicular trafficking to the regulation of membrane lipids of these membrane-bound organelles and the specific enzymatic activities they contain. We also provide perspectives on future challenges that the community needs to tackle and propose approaches to move forward in our understanding of these poorly studied endo-lysosomal genes. This will help harness their potential in designing innovative and efficient treatments to ultimately re-establish neuronal homeostasis in PD but also other diseases involving endo-lysosomal dysfunction.

SCAMP3 promotes breast cancer progression through the c-MYC-β-Catenin-SQSTM1 growth and stemness axis

The cellular trafficking protein secretory-carrier-membrane-protein 3 (SCAMP3) has been previously shown to promote hepatocellular carcinoma, melanoma, glioma and pancreatic adenocarcinoma. Moreover, previous work has shown that SCAMP3 regulates the epidermal growth factor receptor (EGFR) in triple negative breast cancer (TNBC). However, the oncogenic role of SCAMP3 in different molecular subtypes of breast cancer (BRCA) remains largely unknown. In this study, the role of SCAMP3 in different molecular subtypes of BRCA was investigated using in silico, in vitro and in vivo approaches. In silico analysis of BRCA patient samples showed that SCAMP3 is highly overexpressed in different BRCA molecular subtypes, advanced disease grades and lymph node metastatic stages. Depletion of SCAMP3 inhibited BRCA cell growth, stemness, clonogenic potential and migration and promoted autophagy and cellular senescence. The expression of stemness markers CD44 and OCT4A was reduced in SCAMP3-silenced MDA-MB-231 cells. SCAMP3 overexpression promoted cell proliferation, clonogenicity, tumor spheroid formation and migration in vitro and tumor growth in vivo. SCAMP3 promoted epithelial-mesenchymal-transition (EMT) by regulating E-cadherin expression. SCAMP3 enhanced in vivo tumor growth in MDA-MB-231 tumor xenograft mouse model. Mechanistically, SCAMP3 depletion inhibited β-Catenin, c-MYC and SQSTM1 expression, while its overexpression increased the expression of the same oncogenic proteins. Increased SCAMP3 expression associated with increased chemoresistance in BRCA cells while its depletion associated with increased sensitivity to chemotherapy. BRCA patients with high SCAMP3 expression showed poor prognosis, decreased overall survival and relapse free survival relative to counterparts with reduced SCAMP3 expression. These findings suggest that SCAMP3 exerts a wide range of oncogenic effects in different molecular subtypes of BRCA by modulating the c-MYC-β-Catenin-SQSTM1 axis that targets tumor growth, metastasis, stemness and chemoresistance.

An Electrophysiological and Proteomic Analysis of the Effects of the Superoxide Dismutase Mimetic, MnTMPyP, on Synaptic Signalling Post-Ischemia in Isolated Rat Hippocampal Slices

Metabolic stress and the increased production of reactive oxygen species (ROS) are two main contributors to neuronal damage and synaptic plasticity in acute ischemic stroke. The superoxide scavenger MnTMPyP has been previously reported to have a neuroprotective effect in organotypic hippocampal slices and to modulate synaptic transmission after in vitro hypoxia and oxygen-glucose deprivation (OGD). However, the mechanisms involved in the effect of this scavenger remain elusive. In this study, two concentrations of MnTMPyP were evaluated on synaptic transmission during ischemia and post-ischemic synaptic potentiation. The complex molecular changes supporting cellular adaptation to metabolic stress, and how these are modulated by MnTMPyP, were also investigated. Electrophysiological data showed that MnTMPyP causes a decrease in baseline synaptic transmission and impairment of synaptic potentiation. Proteomic analysis performed on MnTMPyP and hypoxia-treated tissue indicated an impairment in vesicular trafficking mechanisms, including reduced expression of Hsp90 and actin signalling. Alterations of vesicular trafficking may lead to reduced probability of neurotransmitter release and AMPA receptor activity, resulting in the observed modulatory effect of MnTMPyP. In OGD, protein enrichment analysis highlighted impairments in cell proliferation and differentiation, such as TGFβ1 and CDKN1B signalling, in addition to downregulation of mitochondrial dysfunction and an increased expression of CAMKII. Taken together, our results may indicate modulation of neuronal sensitivity to the ischemic insult, and a complex role for MnTMPyP in synaptic transmission and plasticity, potentially providing molecular insights into the mechanisms mediating the effects of MnTMPyP during ischemia.

Fungal antitumor protein D1 is internalized via endocytosis and inhibits non-small cell lung cancer proliferation through MAPK signaling pathway

Lung cancer has the highest mortality among cancer-related deaths worldwide. Among lung cancers, non-small cell lung cancer (NSCLC) is the most common histological type. In the previous research, we isolated a protein (D1) from Boletus bicolor that inhibits the proliferation of NSCLC cell lines. In this study, we elucidated the internalization mechanism and antitumor mechanism of protein D1 in A549 cells. Protein D1 has a strong inhibitory effect on A549 cells. It binds to secretory carrier membrane protein 3 on the A549 cell membrane and enters A549 cells by clathrin-mediated endocytosis. In vitro, protein D1 activates mitogen-activated protein kinase (MAPK) signaling pathway. JNK and p38MAPK are the biological targets for protein D1. In vivo, protein D1 inhibits the tumor growth of NSCLC xenografts by inducing apoptosis and inhibiting cell proliferation. Protein D1 alters the expression of genes related to apoptosis, cell cycle, and MAPK signaling pathway in tumor cells.

Genetic regulation of RNA splicing in human pancreatic islets

BACKGROUND

Non-coding genetic variants that influence gene transcription in pancreatic islets play a major role in the susceptibility to type 2 diabetes (T2D), and likely also contribute to type 1 diabetes (T1D) risk. For many loci, however, the mechanisms through which non-coding variants influence diabetes susceptibility are unknown.

RESULTS

We examine splicing QTLs (sQTLs) in pancreatic islets from 399 human donors and observe that common genetic variation has a widespread influence on the splicing of genes with established roles in islet biology and diabetes. In parallel, we profile expression QTLs (eQTLs) and use transcriptome-wide association as well as genetic co-localization studies to assign islet sQTLs or eQTLs to T2D and T1D susceptibility signals, many of which lack candidate effector genes. This analysis reveals biologically plausible mechanisms, including the association of T2D with an sQTL that creates a nonsense isoform in ERO1B, a regulator of ER-stress and proinsulin biosynthesis. The expanded list of T2D risk effector genes reveals overrepresented pathways, including regulators of G-protein-mediated cAMP production. The analysis of sQTLs also reveals candidate effector genes for T1D susceptibility such as DCLRE1B, a senescence regulator, and lncRNA MEG3.

CONCLUSIONS

These data expose widespread effects of common genetic variants on RNA splicing in pancreatic islets. The results support a role for splicing variation in diabetes susceptibility, and offer a new set of genetic targets with potential therapeutic benefit.

SCAMP3 is a mutant EGFR phosphorylation target and a tumor suppressor in lung adenocarcinoma

Mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain constitutively activate EGFR resulting in lung tumorigenesis. Activated EGFR modulates downstream signaling by altering phosphorylation-driven interactions that promote growth and survival. Secretory carrier membrane proteins (SCAMPs) are a family of transmembrane proteins that regulate recycling of receptor proteins, including EGFR. The potential role of SCAMPs in mutant EGFR function and tumorigenesis has not been elucidated. Using quantitative mass-spectrometry-based phosphoproteomics, we identified SCAMP3 as a target of mutant EGFRs in lung adenocarcinoma and sought to further investigate the role of SCAMP3 in the regulation of lung tumorigenesis. Here we show that activated EGFR, either directly or indirectly phosphorylates SCAMP3 at Y86 and this phosphorylation increases the interaction of SCAMP3 with both wild-type and mutant EGFRs. SCAMP3 knockdown increases lung adenocarcinoma cell survival and increases xenograft tumor growth in vivo, demonstrating a tumor suppressor role of SCAMP3 in lung tumorigenesis. The tumor suppressor function is a result of SCAMP3 promoting EGFR degradation and attenuating MAP kinase signaling pathways. SCAMP3 knockdown also increases multinucleated cells in culture, suggesting that SCAMP3 is required for efficient cytokinesis. The enhanced growth, increased colony formation, reduced EGFR degradation and multinucleation phenotype of SCAMP3-depleted cells were reversed by re-expression of wild-type SCAMP3, but not SCAMP3 Y86F, suggesting that Y86 phosphorylation is critical for SCAMP3 function. Taken together, the results of this study demonstrate that SCAMP3 functions as a novel tumor suppressor in lung cancer by modulating EGFR signaling and cytokinesis that is partly Y86 phosphorylation-dependent.

Exosomes and Cell Communication: From Tumour-Derived Exosomes and Their Role in Tumour Progression to the Use of Exosomal Cargo for Cancer Treatment

Simple Summary

Recently, within the research community, exosomes, transporters of bioactive molecules involved in many signalling pathways and cell-to-cell communication with the capacity to alter the tumour microenvironment, have been attracting increasing interest among oncologists. These molecules can play multiple roles, e.g., as useful biomarkers in diagnosis, modulators of the immune system, promoters of the formation of the pre-metastatic niches and cancer metastasis and carriers of substances or factors with anticancer properties. This review focuses on the use of exosomes as a novel therapeutic strategy for cancer treatment. Particularly, it highlights the potential of exosomes as carriers of stem cell differentiation stage factors (SCDSFs) for “cell reprogramming” therapy, a promising research field on which we have reported previously. Here, the main characteristics of this treatment and the advantages that can be obtained using mesenchymal stem cell-derived exosomes up-loaded with the SCDSFs as carriers of these factors are also discussed.

Abstract

Exosomes are nano-vesicle-shaped particles secreted by various cells, including cancer cells. Recently, the interest in exosomes among cancer researchers has grown enormously for their many potential roles, and many studies have focused on the bioactive molecules that they export as exosomal cargo. These molecules can function as biomarkers in diagnosis or play a relevant role in modulating the immune system and in promoting apoptosis, cancer development and progression. Others, considering exosomes potentially helpful for cancer treatment, have started to investigate them in experimental therapeutic trials. In this review, first, the biogenesis of exosomes and their main characteristics was briefly described. Then, the capability of tumour-derived exosomes and oncosomes in tumour microenvironments (TMEs) remodelling and pre-metastatic niche formation, as well as their interference with the immune system during cancer development, was examined. Finally, the potential role of exosomes for cancer therapy was discussed. Particularly, in addition, their use as carriers of natural substances and drugs with anticancer properties or carriers of boron neutron capture therapy (BNCT) and anticancer vaccines for immunotherapy, exosomes as biological reprogrammers of cancer cells have gained increased consensus. The principal aspects and the rationale of this intriguing therapeutic proposal are briefly considered.

Comprehensive Evaluation of Endocytosis-Associated Protein SCAMP3 in Hepatocellular Carcinoma

Background

Secretory carrier membrane proteins 3 (SCAMP3) is an endocytosis-associated protein involved in regulating endosomal pathways and the trafficking of vital signaling receptors. This study aimed to comprehensively assess the role of SCAMP3 in hepatocellular carcinoma (HCC) by integrated bioinformatics analysis.

Methods

In this study, bioinformatics databases were used to explore the differential expression status and prognostic value of SCAMP3 gene in HCC, and bioinformatics analyses of survival data and interactors of SCAMP3 were conducted to predict the prognostic value of SCAMP3 in HCC.

Results

Using the TCGA data, our data shows that SCAMP3 mRNA expression is most significantly different between liver and hepatocellular carcinoma tissues and higher expression of SCAMP3 has unfavorable prognostic significance in HCC. Tumor grade, stage, and gender also showed a significant relevance with SCAMP3 expression. High SCAMP3 expression of males revealed significantly poorer survival and progression compared with low SCAMP3 expression of males. BioGRID statistics explores 79 unique interactions with SCAMP3 and multiple post translational modifications. Further analysis finds that SOCS2 may negatively correlate with SCAMP3, while GBA, MX1, and DDOST positively correlate with SCAMP3. Moreover, ncRNA analysis shows that SCAMP3 gene expression is positively associated with lncRNA SBF2-AS1 and negatively related with Has-miR-145. The expressions of SBF2-AS1 and Has-miR-145 are also significantly related with survival in HCC.

Discussion

SCAMP3 expression can be affected by multiple genes or ncRNAs expression that are associated with survival, thus suggesting that SCAMP3 can be used as a clinical diagnosis and prognostic biomarker in HCC.

Delineating WWOX Protein Interactome by Tandem Affinity Purification-Mass Spectrometry: Identification of Top Interactors and Key Metabolic Pathways Involved

It has become clear from multiple studies that WWOX (WW domain-containing oxidoreductase) operates as a "non-classical" tumor suppressor of significant relevance in cancer progression. Additionally, WWOX has been recognized for its role in a much wider array of human pathologies including metabolic conditions and central nervous system related syndromes. A myriad of putative functional roles has been attributed to WWOX mostly through the identification of various binding proteins. However, the reality is that much remains to be learned on the key relevant functions of WWOX in the normal cell. Here we employed a Tandem Affinity Purification-Mass Spectrometry (TAP-MS) approach in order to better define direct WWOX protein interactors and by extension interaction with multiprotein complexes under physiological conditions on a proteomic scale. This work led to the identification of both well-known, but more importantly novel high confidence WWOX interactors, suggesting the involvement of WWOX in specific biological and molecular processes while delineating a comprehensive portrait of WWOX protein interactome. Of particular relevance is WWOX interaction with key proteins from the endoplasmic reticulum (ER), Golgi, late endosomes, protein transport, and lysosomes networks such as SEC23IP, SCAMP3, and VOPP1. These binding partners harbor specific PPXY motifs which directly interact with the amino-terminal WW1 domain of WWOX. Pathway analysis of WWOX interactors identified a significant enrichment of metabolic pathways associated with proteins, carbohydrates, and lipids breakdown. Thus, suggesting that WWOX likely plays relevant roles in glycolysis, fatty acid degradation and other pathways that converge primarily in Acetyl-CoA generation, a fundamental molecule not only as the entry point to the tricarboxylic acid (TCA) cycle for energy production, but also as the key building block for de novo synthesis of lipids and amino acids. Our results provide a significant lead on subsets of protein partners and enzymatic complexes with which full-length WWOX protein interacts with in order to carry out its metabolic and other biological functions while also becoming a valuable resource for further mechanistic studies.

Endosomal Size and Membrane Leakiness Influence Proton Sponge-Based Rupture of Endosomal Vesicles

In gene therapy, endosomal escape represents a major bottleneck since nanoparticles often remain entrapped inside endosomes and are trafficked toward the lysosomes for degradation. A detailed understanding of the endosomal barrier would be beneficial for developing rational strategies to improve transfection and endosomal escape. By visualizing individual endosomal escape events in live cells, we obtain insight into mechanistic factors that influence proton sponge-based endosomal escape. In a comparative study, we found that HeLa cells treated with JetPEI/pDNA polyplexes have a 3.5-fold increased endosomal escape frequency compared to ARPE-19 cells. We found that endosomal size has a major impact on the escape capacity. The smaller HeLa endosomes are more easily ruptured by the proton sponge effect than the larger ARPE-19 endosomes, a finding supported by a mathematical model based on the underlying physical principles. Still, it remains intriguing that even in the small HeLa endosomes, <10% of the polyplex-containing endosomes show endosomal escape. Further experiments revealed that the membrane of polyplex-containing endosomes becomes leaky to small compounds, preventing effective buildup of osmotic pressure, which in turn prevents endosomal rupture. Analysis of H1299 and A549 cells revealed that endosomal size determines endosomal escape efficiency when cells have comparable membrane leakiness. However, at high levels of membrane leakiness, buildup of osmotic pressure is no longer possible, regardless of endosomal size. Based on our findings that both endosomal size and membrane leakiness have a high impact on proton sponge-based endosomal rupture, we provide important clues toward further improvement of this escape strategy.