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Vacuolar protein sorting 35 (VPS35), a critical component of the retromer complex, plays a pivotal role in the pathogenesis of neurodegenerative diseases (NDs). It is involved in protein transmembrane sorting, facilitating the transport from endosomes to the trans‐Golgi network (TGN) and plasma membrane. Recent investigations have compellingly associated mutations in the VPS35 gene with neurodegenerative disorders such as Parkinson's and Alzheimer's disease. These genetic alterations are implicated in protein misfolding, disrupted autophagic processes, mitochondrial dysregulation, and synaptic impairment. Furthermore, VPS35 exerts a notable impact on neurogenesis by influencing neuronal functionality, protein conveyance, and synaptic performance. Dysregulation or mutation of VPS35 may escalate the progression of neurodegenerative conditions, underscoring its pivotal role in safeguarding neuronal integrity. This review comprehensively discusses the role of VPS35 and its functional impairments in NDs. Furthermore, we provide an overview of the impact of VPS35 on neurogenesis and further explore the intricate relationship between neurogenesis and NDs. These research advancements offer novel perspectives and valuable insights for identifying potential therapeutic targets in the treatment of NDs. [ABSTRACT FROM AUTHOR]

The endosomal system maintains cellular homeostasis by coordinating multiple vesicular trafficking events, and the retromer complex plays a critical role in endosomal cargo recognition and sorting. Here, we demonstrate an essential role for the small GTPase RAB21 in regulating retromer-mediated recycling of the glucose transporter SLC2A1/GLUT1 and macroautophagy/autophagy. RAB21 depletion mis-sorts SLC2A1 to lysosomes and affects glucose uptake, thereby activating the AMPK-ULK1 pathway to increase autophagic flux. RAB21 depletion also increases lysosome function. Notably, RAB21 depletion does not overtly affect retrograde transport of IGF2R/CI-M6PR or WLS from endosomes to the trans-Golgi network. We speculate that RAB21 regulates fission of retromer-decorated endosomal tubules, as RAB21 depletion causes accumulation of the SNX27-containing retromer complex on enlarged endosomes at the perinuclear region. Functionally, RAB21 depletion sensitizes cancer cells to energy stress and inhibits tumor growth in vivo, suggesting an oncogenic role for RAB21. Overall, our study illuminates the role of RAB21 in regulating endosomal dynamics and maintaining cellular energy homeostasis and suggests RAB21 as a potential metabolic target for cancer therapy. [ABSTRACT FROM AUTHOR]

Background: The endosomal retromer complex system is a key controller for trafficking of proteins. Downregulation of its recognition core proteins, such as VPS35, is present in Alzheimer's disease (AD) brain, whereas its normalization prevents the development of AD pathology in a transgenic model with amyloid-β deposits and tau tangles.Objective: Assess the effect of targeting VPS35 after the AD pathology and memory impairments have developed.Methods: Twelve-month-old triple transgenic mice were treated with a small pharmacological chaperone, TPT-172, or vehicle for 14 weeks. At the end of this period, the effect of the drug on their phenotype was evaluated.Results: While control mice had a decline of learning and memory, the group receiving the chaperone did not. Moreover, when compared with controls the treated mice had significantly less amyloid-β peptides and phosphorylated tau, elevation of post-synaptic protein, and reduction in astrocytes activation.Conclusion: Taken together, our findings demonstrate that pharmacologic stabilization of the retromer recognition core is beneficial also after the AD-like pathologic phenotype is established. [ABSTRACT FROM AUTHOR]

Intracellular bacterial pathogens secrete a repertoire of effector proteins into host cells that are required to hijack cellular pathways and cause disease. Despite decades of research, the molecular functions of most bacterial effectors remain unclear. To address this gap, we generated quantitative genetic interaction profiles between 36 validated and putative effectors from three evolutionarily divergent human bacterial pathogens and 4,190 yeast deletion strains. Correlating effector-generated profiles with those of yeast mutants, we recapitulated known biology for several effectors with remarkable specificity and predicted previously unknown functions for others. Biochemical and functional validation in human cells revealed a role for an uncharacterized component of the Salmonella SPI-2 translocon, SseC, in regulating maintenance of the Salmonella vacuole through interactions with components of the host retromer complex. These results exhibit the power of genetic interaction profiling to discover and dissect complex biology at the host-pathogen interface.

The mitochondrial unfolded protein response (UPRmt) can be triggered in a cell-non-autonomous fashion across multiple tissues in response to mitochondrial dysfunction. The ability to communicate information about the presence of mitochondrial stress enables a global response that can ultimately better protect an organism from local mitochondrial challenges. We find that animals use retromer-dependent Wnt signaling to propagate mitochondrial stress signals from the nervous system to peripheral tissues. Specifically, the polyQ40-triggered activation of mitochondrial stress or reduction of cco-1 (complex IV subunit) in neurons of C. elegans results in the Wnt-dependent induction of cell-non-autonomous UPRmt in peripheral cells. Loss-of-function mutations of retromer complex components that are responsible for recycling the Wnt secretion-factor/MIG-14 prevent Wnt secretion and thereby suppress cell-non-autonomous UPRmt. Neuronal expression of the Wnt ligand/EGL-20 is sufficient to induce cell-non-autonomous UPRmt in a retromer complex-, Wnt signaling-, and serotonin-dependent manner, clearly implicating Wnt signaling as a strong candidate for the "mitokine" signal.

Abstract Parkinson's disease (PD) is a neurodegenerative disease that is common in middle‐aged and elderly people, and its onset is related to multiple factors, such as heredity, environment, and age. The vesicle protein sorting 35 (VPS35) gene was found to be a late‐onset autosomal dominant familial PD (PARK17) causative gene. The protein encoded by this gene is located in the endosome and aggregates with other membrane proteins to form a retromer complex, which participates in the membrane protein cycle between the endosome and the Golgi network. Increasing evidence shows that VPS35 may participate in the pathogenesis of PD by affecting autophagy, mitochondria, neurosynaptic transmission, dopamine signaling pathways, and so forth, and it can interact with other disease‐causing genes of familial PD. This article aimed to review the functions of VPS35 and the mechanism of its mutations in PD that have been discovered in recent years.

Alessia Filippone, Tiffany Smith, Domenico Pratico Alzheimer’s Center at Temple, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USACorrespondence: Domenico PraticoAlzheimer’s Center at Temple, Lewis Katz School of Medicine, Temple University, 3500 North Broad Street, MERB, suite 1160, Philadelphia, PA, 19140, USATel +1 215-707-9380Fax +1 215-707-2746Email praticod@temple.eduIntroduction: Transport through endothelial cells of the blood–brain barrier (BBB) involves a complex group of structures of the endo-lysosome system such as early and late endosomes, and the retromer complex system. Studies show that neuronal dysregulation of the vacuolar protein sorting 35 (VPS35), the main component of the retromer complex recognition core, results in altered protein trafficking and degradation and is involved in neurodegeneration. Since the functional role of VPS35 in endothelial cells has not been fully investigated, in the present study we aimed at characterizing the effect of its downregulation on these pathways.Methods: Genetic silencing of VPS35 in human brain endothelial cells; measurement of retromer complex system proteins, autophagy and ubiquitin-proteasome systems.Results: VPS35-downregulated endothelial cells had increased expression of LC3B2/1 and more ubiquitinated products, markers of autophagy flux and impaired proteasome activity, respectively. Additionally, compared with controls VPS35 downregulation resulted in significant accumulation of tau protein and its phosphorylated isoforms.Discussion: Our findings demonstrate that in brain endothelial cells retromer complex dysfunction by influencing endosome-lysosome degradation pathways results in altered proteostasis. Restoration of the retromer complex system function should be considered a novel therapeutic approach to rescue endothelial protein transport.Keywords: retromer complex, brain endothelial cells, endosomal trafficking, tau protein, autophagy, ubiquitin-proteasome, Alzheimer’s disease

Perturbations of the endolysosomal pathway have been suggested to play an important role in the pathogenesis of several neurodegenerative diseases, including Parkinson's disease (PD) and Alzheimer's disease (AD). Specifically, VPS35 and the retromer complex play an important role in the endolysosomal system and are implicated in the pathophysiology of these diseases. A single missense mutation in VPS35, Asp620Asn (D620N), is known to cause late-onset, autosomal dominant familial PD. In this review, we focus on the emerging role of the PD-linked D620N mutation in causing retromer dysfunction and dissect its implications in neurodegeneration. Additionally, we will discuss how VPS35 and the retromer are linked to AD, amyotrophic lateral sclerosis, and primary tauopathies. Interestingly, reduced levels of VPS35 and other retromer components have been observed in post-mortem brain tissue, suggesting a role for the retromer in the pathophysiology of these diseases. This review will provide a comprehensive dive into the mechanisms of VPS35 dysfunction in neurodegenerative diseases. Furthermore, we will highlight outstanding questions in the field and the retromer as a therapeutic target for neurodegenerative disease at large.

Vesicle Protein Sorting 35 (VPS35) is a novel oncogene that promotes tumor growth through the PI3K/AKT signaling in hepatocellular carcinoma (HCC). However, the role of VPS35 in HCC metastasis and the underlying mechanisms remain largely unclear. In this study, we observed that overexpression of VPS35 enhanced hepatoma cell invasion and metastasis by inducing epithelial–mesenchymal transition (EMT)-related gene expression. Conversely, knockout of VPS35 significantly inhibited hepatoma cell migration and invasion. Furthermore, depletion of VPS35 decreased the lung metastasis of HCC in nude mice. By transcriptome analysis, we determined that VPS35 promoted HCC metastasis by activating the Wnt/non-canonical planar cell polarity (PCP) pathway. Mechanistically, VPS35 activated the PCP pathway by regulating membrane sorting and trafficking of Frizzled-2 (FZD2) and ROR1 in hepatoma cells. Collectively, our results indicate that VPS35 promotes HCC metastasis via enhancing the Wnt/PCP signaling, thus providing a potential prognostic marker and therapeutic target for HCC.

Neuronal aging is associated with numerous diseases resulting in memory impairment and functional decline. A common hallmark of these disorders is the accumulation of intracellular and extracellular protein aggregates. The retromer complex plays a central role in sorting proteins by marking them for reuse rather than degradation. Retromer dysfunction has been shown to induce protein aggregates and neurodegeneration, suggesting that it may be important for age-related neuronal decline and disease progression. Despite this, little is known about how aging influences retromer stability and the proteins with which it interacts. Detailed insights into age-dependent changes in retromer structure and function could provide valuable information towards treating and preventing many age-related neurodegenerative disorders. Here, we visit age-related pathways which interact with retromer function that ought to be further explored to determine its role in age-related neurodegeneration. [ABSTRACT FROM AUTHOR]

Plasma membrane protein trafficking is of fundamental importance for cell function and cell integrity of neurons and includes regulated protein recycling. In this work, we report a novel role of the endoplasmic reticulum (ER) for protein recycling as discovered in trafficking studies of the ion channel TRPL in photoreceptor cells of Drosophila. TRPL is located within the rhabdomeric membrane from where it is endocytosed upon light stimulation and stored in the cell body. Conventional immunohistochemistry as well as stimulated emission depletion super‐resolution microscopy revealed TRPL storage at the ER after illumination, suggesting an unusual recycling route of TRPL. Our results also imply that both phospholipase D (PLD) and retromer complex are required for correct recycling of TRPL to the rhabdomeric membrane. Loss of PLD activity in PLD3.1 mutants results in enhanced degradation of TRPL. In the retromer mutant vps35MH20, TRPL is trapped in a Rab5‐positive compartment. Evidenced by epistatic analysis in the double mutant PLD3.1vps35MH20, PLD activity precedes retromer function. We propose a model in which PLD and retromer function play key roles in the transport of TRPL to an ER enriched compartment. [ABSTRACT FROM AUTHOR]

Background: The vacuolar protein sorting 35 (VPS35) is the main component of the retromer recognition core complex system which regulates intracellular cargo protein sorting and trafficking. Downregulation of VPS35 has been linked to the pathogenesis of neurodegenerative disorders such Alzheimer's and Parkinson's diseases via endosome dysregulation.Objective: Here we show that the genetic manipulation of VPS35 affects intracellular degradation pathways.Methods: A neuronal cell line expressing human APP Swedish mutant was used. VPS35 silencing was performed treating cells with VPS35 siRNA or Ctr siRNA for 72 h.Results: Downregulation of VPS35 was associated with alteration of autophagy flux and intracellular accumulation of acidic and ubiquitinated aggregates suggesting that dysfunction of the retromer recognition core leads to a significant alteration in both pathways.Conclusion: Taken together, our data demonstrate that besides cargo sorting and trafficking, VPS35 by supporting the integral function of the retromer complex system plays an important role also as a critical regulator of intracellular degradation pathways. [ABSTRACT FROM AUTHOR]

Abstract Background The vacuolar protein sorting 35 (VPS35) is a major component of the retromer complex system, an ubiquitous multiprotein assembly responsible for sorting and trafficking protein cargos out of the endosomes. VPS35 can regulate APP metabolism and Aβ formation, and its levels are reduced in Alzheimer’s disease (AD) brains. We and others demonstrated that VPS35 genetic manipulation modulates the phenotype of mouse models of AD. However, the translational value of this observation remains to be investigated. Methods Triple transgenic mice were randomized to receive a pharmacological chaperone, which stabilizes the retromer complex, and the effect on their AD-like phenotype assessed. Results Compared with controls, treated mice had a significant improvement in learning and memory, an elevation of VPS35 levels, and improved synaptic integrity. Additionally, the same animals had a significant decrease in Aβ levels and deposition, reduced tau phosphorylation and less astrocytes activation. Conclusions Our study demonstrates that the enhancement of retromer function by pharmacological chaperones is a potentially novel and viable therapy against AD.

Aberrations in membrane trafficking pathways have profound effects in cellular dynamics of cellular sorting processes and can drive severe physiological outcomes. Sorting nexin 27 (SNX27) is a metazoan-specific sorting nexin protein from the PX-FERM domain family and is required for endosomal recycling of many important transmembrane receptors. Multiple studies have shown SNX27-mediated recycling requires association with retromer, one of the best-known regulators of endosomal trafficking. SNX27/retromer downregulation is strongly linked to Down’s Syndrome (DS) via glutamate receptor dysfunction and to Alzheimer’s Disease (AD) through increased intracellular production of amyloid peptides from amyloid precursor protein (APP) breakdown. SNX27 is further linked to addiction via its role in potassium channel trafficking, and its over-expression is linked to tumorigenesis, cancer progression, and metastasis. Thus, the correct sorting of multiple receptors by SNX27/retromer is vital for normal cellular function to prevent human diseases. The role of SNX27 in regulating cargo recycling from endosomes to the cell surface is firmly established, but how SNX27 assembles with retromer to generate tubulovesicular carriers remains elusive. Whether SNX27/retromer may be a putative therapeutic target to prevent neurodegenerative disease is now an emerging area of study. This review will provide an update on our molecular understanding of endosomal trafficking events mediated by the SNX27/retromer complex on endosomes.

The vacuolar protein sorting 35 (VPS35) gene located on chromosome 16 has recently emerged as a cause of late-onset familial Parkinson's disease (PD) (PARK17). The gene encodes a 796-residue protein nearly ubiquitously expressed in human tissues. The protein localizes on endosomes where it assembles with other peripheral membrane proteins to form the retromer complex. How VPS35 mutations induce dopaminergic neuron degeneration in humans is still unclear. Because the retromer complex recycles the receptors that mediate the transport of hydrolase to lysosome, it has been suggested that VPS35 mutations lead to impaired lysosomal and autophagy function. Recent studies also demonstrated that VPS35 and the retromer complex influence mitochondrial homeostasis, suggesting that VPS35 mutations elicit mitochondrial dysfunction. More recent studies have identified a key role of VPS35 in neurotransmission, whilst others reported a functional interaction between VPS35 and other genes associated with familial PD, including α-SYNUCLEIN-PARKIN–LRRK2. Here, we review the biological role of VPS35 protein, the VPS35 mutations identified in human PD patients, and the potential molecular mechanism by which VPS35 mutations can induce progressive neurodegeneration in PD. [ABSTRACT FROM AUTHOR]

Several symptomatic treatments for Parkinson's disease (PD) are currently available. Still, the challenge today is to find a therapy that might reduce degeneration and slow down disease progression. The identification of pathogenic mutations in familial Parkinsonism (fPD) associated to the monogenic forms of PD provided pathophysiological insights and highlighted novel targets for therapeutic intervention. Mutations in the VPS35 gene have been associated with autosomal dominant fPD and a clinical phenotype indistinguishable from idiopathic PD. Although VPS35 mutations are relatively rare causes of PD, their study may help understanding specific cellular and molecular alterations that lead to accumulation α-synuclein in neurons of PD patients. Interacting with such mechanisms may provide innovative therapeutic approaches. We review here the evidence on the physiological role of VPS35 as a key intracellular trafficking protein controlling relevant neuronal functions. We further analyze VPS35 activity on α-synuclein degradation pathways that control the equilibrium between α-synuclein clearance and accumulation. Finally, we highlight the strategies for increasing VPS35 levels as a potential tool to treat PD.

Sodium metabisulfite (Na2S2O5) is widely used as a preservative in the food and wine industry. However, it causes varying degrees of cellular damage to organisms. In order to improve our knowledge regarding its cyto-toxicity, a genome-wide screen using the yeast single deletion collection was performed. Additionally, a total of 162 Na2S2O5-sensitive strains and 16 Na2S2O5-tolerant strains were identified. Among the 162 Na2S2O5 tolerance-related genes, the retromer complex was the top enriched cellular component. Further analysis demonstrated that retromer complex deletion leads to increased sensitivity to Na2S2O5, and that Na2S2O5 can induce mislocalization of retromer complex proteins. Notably, phosphatidylinositol 3-monophosphate kinase (PI3K) complex II, which is important for retromer recruitment to the endosome, might be a potential regulator mediating retromer localization and the yeast Na2S2O5 tolerance response. Na2S2O5 can decrease the protein expressions of Vps34, which is the component of PI3K complex. Therefore, Na2S2O5-mediated retromer redistribution might be caused by the effects of decreased Vps34 expression levels. Moreover, both pharmaceutical inhibition of Vps34 functions and deletions of PI3K complex II-related genes affect cell tolerance to Na2S2O5. The results of our study provide a global picture of cellular components required for Na2S2O5 tolerance and advance our understanding concerning Na2S2O5-induced cytotoxicity effects.

Background: The vacuolar protein sorting 35 (VPS35) is a major component of the retromer complex system, an ubiquitous multiprotein assembly responsible for sorting and trafficking protein cargos out of the endosomes. VPS35 can regulate APP metabolism and Aβ formation, and its levels are reduced in Alzheimer's disease (AD) brains. We and others demonstrated that VPS35 genetic manipulation modulates the phenotype of mouse models of AD. However, the translational value of this observation remains to be investigated. Methods: Triple transgenic mice were randomized to receive a pharmacological chaperone, which stabilizes the retromer complex, and the effect on their AD-like phenotype assessed. Results: Compared with controls, treated mice had a significant improvement in learning and memory, an elevation of VPS35 levels, and improved synaptic integrity. Additionally, the same animals had a significant decrease in Aβ levels and deposition, reduced tau phosphorylation and less astrocytes activation. Conclusions: Our study demonstrates that the enhancement of retromer function by pharmacological chaperones is a potentially novel and viable therapy against AD. [ABSTRACT FROM AUTHOR]

Several symptomatic treatments for Parkinson's disease (PD) are currently available. Still, the challenge today is to find a therapy that might reduce degeneration and slow down disease progression. The identification of pathogenic mutations in familial Parkinsonism (fPD) associated to the monogenic forms of PD provided pathophysiological insights and highlighted novel targets for therapeutic intervention. Mutations in the VPS35 gene have been associated with autosomal dominant fPD and a clinical phenotype indistinguishable from idiopathic PD. Although VPS35 mutations are relatively rare causes of PD, their study may help understanding specific cellular and molecular alterations that lead to accumulation α-synuclein in neurons of PD patients. Interacting with such mechanisms may provide innovative therapeutic approaches. We review here the evidence on the physiological role of VPS35 as a key intracellular trafficking protein controlling relevant neuronal functions. We further analyze VPS35 activity on α-synuclein degradation pathways that control the equilibrium between α-synuclein clearance and accumulation. Finally, we highlight the strategies for increasing VPS35 levels as a potential tool to treat PD. [ABSTRACT FROM AUTHOR]

Vps35 (vacuolar protein sorting 35) is a key component of retromer that consists of Vps35, Vps26, and Vps29 trimers, and sortin nexin dimers. Dysfunctional Vps35/retromer is believed to be a risk factor for development of various neurodegenerative diseases. Vps35Neurod6 mice, which selectively knock out Vps35 in Neurod6-Cre+ pyramidal neurons, exhibit age-dependent impairments in terminal differentiation of dendrites and axons of cortical and hippocampal neurons, neuro-degenerative pathology (i.e., increases in P62 and Tdp43 (TAR DNA-binding protein 43) proteins, cell death, and reactive gliosis), and neonatal death. The relationships among these phenotypes and the underlying mechanisms remain largely unclear. Here, we provide evidence that expression of low level of VPS35-mCherry fusion protein in Vps35Neurod6 mice could diminish the phenotypes in an age-dependent manner. Specifically, we have generated a conditional transgenic mouse line, LSL-Vps35-mCherry, which expresses VPS35-mCherry fusion protein in a Cre-dependent manner. Crossing LSL-Vps35-mCherry with Vps35Neurod6 to obtain TgVPS35-mCherry, Vps35Neurod6 mice prevent the neonatal death and diminish the dendritic morphogenesis deficit and gliosis at the neonatal, but not the adult age. Further studies revealed that the Vps35-mCherry transgene expression was low, and the level of Vps35 mRNA comprised only ~5–7% of the Vps35 mRNA of control mice. Such low level of VPS35-mCherry could restore the amount of other retromer components (Vps26a and Vps29) at the neonatal age (P14). Importantly, the neurodegenerative pathology presented in the survived adult TgVps35-mCherry; Vps35Neurod6 mice. These results demonstrate the sufficiency of low level of VPS35-mCherry fusion protein to diminish the phenotypes in Vps35Neurod6 mice at the neonatal age, verifying a key role of neuronal Vps35 in stabilizing retromer complex proteins, and supporting the view for Vps35 as a potential therapeutic target for neurodegenerative diseases.

Parkinson's disease (PD) is one of the most common neurodegenerative disorders, affecting 1–1.5% of the total population. While progress has been made in understanding the neurodegenerative mechanisms that lead to cell death in late stages of PD, mechanisms for early, causal pathogenic events are still elusive. Recent developments in PD genetics increasingly point at endolysosomal (E‐L) system dysfunction as the early pathomechanism and key pathway affected in PD. Clathrin‐mediated synaptic endocytosis, an integral part of the neuronal E‐L system, is probably the main early target as evident in auxilin, RME‐8, and synaptojanin‐1 mutations that cause PD. Autophagy, another important pathway in the E‐L system, is crucial in maintaining proteostasis and a healthy mitochondrial pool, especially in neurons considering their inability to divide and requirement to function an entire life‐time. PINK1 and Parkin mutations severely perturb autophagy of dysfunctional mitochondria (mitophagy), both in the cell body and synaptic terminals of dopaminergic neurons, leading to PD. Endolysosomal sorting and trafficking is also crucial, which is complex in multi‐compartmentalized neurons. VPS35 and VPS13C mutations noted in PD target these mechanisms. Mutations in GBA comprise the most common risk factor for PD and initiate pathology by compromising lysosomal function. This is also the case for ATP13A2 mutations. Interestingly, α‐synuclein and LRRK2, key proteins involved in PD, function in different steps of the E‐L pathway and target their components to induce disease pathogenesis. In this review, we discuss these E‐L system genes that are linked to PD and how their dysfunction results in PD pathogenesis. This article is part of the Special Issue "Synuclein". [ABSTRACT FROM AUTHOR]

Sorting nexin 27 (SNX27), a PDZ (Postsynaptic density-95/Discs large/Zonula occludens 1) domain-containing protein, cooperates with a retromer complex, which regulates intracellular trafficking and the abundance of membrane proteins. Since the carboxyl terminus of aquaporin-2 (AQP2c) has a class I PDZ-interacting motif (X-T/S-X-Φ), the role of SNX27 in the regulation of AQP2 was studied. Co-immunoprecipitation assay of the rat kidney demonstrated an interaction of SNX27 with AQP2. Glutathione S-transferase (GST) pull-down assays revealed an interaction of the PDZ domain of SNX27 with AQP2c. Immunocytochemistry of HeLa cells co-transfected with FLAG-SNX27 and hemagglutinin (HA)-AQP2 also revealed co-localization throughout the cytoplasm. When the PDZ domain was deleted, punctate HA-AQP2 labeling was localized in the perinuclear region. The labeling was intensively overlaid by Lysotracker staining but not by GM130 labeling, a cis-Golgi marker. In rat kidneys and primary cultured inner medullary collecting duct cells, the subcellular redistribution of SNX27 was similar to AQP2 under 1-deamino-8-D-arginine vasopressin (dDAVP) stimulation/withdrawal. Cell surface biotinylation assay showed that dDAVP-induced AQP2 translocation to the apical plasma membrane was unaffected after SNX27 knockdown in mpkCCD cells. In contrast, the dDAVP-induced AQP2 protein abundance was significantly attenuated without changes in AQP2 mRNA expression. Moreover, the AQP2 protein abundance was markedly declined during the dDAVP withdrawal period after stimulation under SNX27 knockdown, which was inhibited by lysosome inhibitors. Autophagy was induced after SNX27 knockdown in mpkCCD cells. Lithium-induced nephrogenic diabetes insipidus in rats revealed a significant downregulation of SNX27 in the kidney inner medulla. Taken together, the PDZ domain-containing SNX27 interacts with AQP2 and depletion of SNX27 contributes to the autophagy-lysosomal degradation of AQP2.

Retromer complex plays a crucial role in intracellular protein trafficking and is conserved throughout the eukaryotes including malaria parasite, Plasmodium falciparum , where it is partially conserved. The assembly of retromer complex in RBC stages of malarial parasite is extremely difficult to explore because of its complicated physiology, small size, and intra-erythrocytic location. Nonetheless, understanding of retromer assembly may pave new ways for the development of novel antimalarials targeting parasite-specific protein trafficking pathways. Here, we investigated the assembly of retromer complex in P . falciparum , by an immunosensing method through highly sensitive Surface Plasmon Resonance (SPR) technique. After taking leads from the bioinformatics search and literature, different interacting proteins were identified and specific antibodies were raised against them. The sensor chip was prepared by covalently linking antibody specific to one component and the whole cell lysate was passed through it in order to trap the interacting complex. Antibodies raised against other interacting components were used to detect them in the trapped complex on the SPR chip. We were able to detect three different components in the retromer complex trapped by the immobilized antibody specific against a different component on a sensor chip. The assay was reproduced and validated in a different two-component CD74-MIF system in mammalian cells. We, thus, illustrate the assembly of retromer complex in P . falciparum through a bio-sensing approach that combines SPR with immunosensing requiring a very small amount of sample from the native source. [ABSTRACT FROM AUTHOR]

During endocytosis, molecules are internalized by the cell through the invagination of the plasma membrane. Endocytosis is required for proper cell function and for normal development in Drosophila . One component of the endocytic pathway is the retromer complex, which recycles transmembrane proteins to other parts of the cell such as the plasma membrane and the trans -Golgi network. Previous studies have shown that mutations to the retromer complex result in developmental defects in Drosophila . In humans, retromer dysfunction has been implicated in Alzheimer's and Parkinson's disease, but little is known about the role of the retromer complex in Drosophila oogenesis. In the current project, we examined the role of the retromer protein Vps26 in oogenesis by characterizing the phenotype of vps26 germline clones. Immunofluorescence was used to visualize the expression of membrane proteins and vesicular trafficking markers in mutant egg chambers. We find that vps26 germline clones exhibit a signaling defect between the germline cells and follicle cells indicated by an increase in LysoTracker staining of the border cells in the mutants. We show that this signaling defect in vps26 mutants may be the result of impaired Notch signaling based on the misexpression of multiple proteins in the Notch signaling pathway in vps26 mutants. [ABSTRACT FROM AUTHOR]

Deficiencies of the retrograde transport mediated by the retromer complex have been described in Alzheimer's disease (AD). Genetic manipulation of retromer modulates brain amyloidosis in Tg2576 mice. However, whether the complex is altered during the development of the AD-like phenotype remains unknown. In this study we assayed the expression levels of the vacuolar sorting protein 35 (VPS35), VPS26, VPS29, and its cargo proteins, cation independent mannose 6-phosphate receptor, sortilin-related receptor in brains of Tg2576 and controls at the ages of 3, 8, and 14 months. While cortex showed an age-dependent decrease in all but VPS29, levels of the same proteins in the cerebellum were unchanged at any age. Neuronal cells expressing human amyloid beta precursor protein Swedish mutant had also reduced retromer complex levels. However, incubation with a pharmacological chaperone dose-dependently restored these levels together with a reduction in amyloid beta. Our study is the first to show that in a transgenic mouse model of AD the changes in the expression levels of the retromer complex are age and region dependent, and that the complex is a viable therapeutic target since its deficiency can be restored pharmacologically by a retromer chaperone. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a neurodegenerative disorder involving the loss of dopaminergic neurons in the brain. Following the discovery of the PD-causing D620N mutation in the VPS35 (Vacuolar sorting protein 35) gene, dysfunction in the subcellular retromer complex has been strongly implicated in pathogenesis of PD. Although the function and dysfunction of the retromer has been a focus of study for some time, the role of this complex in the development of PD is not fully understood. Investigating cellular alterations that occur when the retromer is rendered dysfunctional, such as when the D620N disease-causing mutation is introduced into various model systems, shows that endosomal processing defects are major contributors to the disease phenotype. Altered trafficking of retromer cargo molecules, reduced cellular survival and altered processing of alpha-synuclein have all been observed in the presence of the D620N mutation. In addition, interactions between the retromer and the protein products of other familial Parkinsonism-related genes, has made the retromer a prime target of research in PD. This review gives an overview of the changes in retromer function, identified thus far, that may contribute to the neurodegeneration observed in PD. [ABSTRACT FROM AUTHOR]

Retromer is a protein complex that plays a central role in endosomal trafficking, and retromer dysfunction has been linked to a growing number of neurological disorders. The process of intracellular trafficking and recycling is crucial for maintaining normal intracellular homeostasis, which is partly achieved through retromer complex. The retromer complex plays a primary role in sorting out the cargoes from endosomes back to the cell surface for reuse, to the trans-Golgi network (TGN) or alternatively to specialized endomembrane compartments away from lysosomal-mediated degradation. In most cases, the retromer acts as a core that interacts with associated proteins such as sorting nexin family member 27 (SNX27), the members of the vacuolar protein sorting 10 (VPS10) receptor family, the major endosomal actin polymerization-promoting complex known as wiskott-aldrich syndrome protein and scar homologue (WASH) or other proteins together in sorting the cargoes through various pathways, and some of these cargoes are risk factors for neurodegenerative diseases. Normally, there is a coordinated relationship between these pathways, however, when there is a defect such as haplo-insufficiency or mutation in itself or one or several units of retromer; it will lead to various pathologies.Here, we will summarize the molecular architecture of retromer complex and the roles of this system in intracellular trafficking signaling on pathogenesis of neurodegenerative diseases.