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Phosphatidylinositol 3,5-bisphosphate enables transport of proteins to synaptic sites.

Trafficking of cell-surface proteins from endosomes to the plasma membrane is a key mechanism to regulate synaptic function. In non-neuronal cells, proteins recycle to the plasma membrane either via the SNX27-Retromer-WASH pathway or via the recently discovered SNX17-Retriever-CCC-WASH pathway. While SNX27 is responsible for the recycling of key neuronal receptors, the roles of SNX17 in neurons are less understood. Here, using cultured hippocampal neurons, we demonstrate that the SNX17 pathway regulates synaptic function and plasticity. Disruption of this pathway results in a loss of excitatory synapses and prevents structural plasticity during chemical long-term potentiation (cLTP). cLTP drives SNX17 recruitment to synapses, where its roles are in part mediated by regulating the surface expression of β1-integrin. SNX17 recruitment relies on NMDAR activation, CaMKII signaling, and requires binding to the Retriever and PI(3)P. Together, these findings provide molecular insights into the regulation of SNX17 at synapses and define key roles for SNX17 in synaptic maintenance and in regulating enduring forms of synaptic plasticity., (© 2023 Rivero-Ríos et al.)

The Galician Bank (GB) is a seamount located 180 km away from the Galician coast (Northwest Spain), in the Northeast Atlantic Ocean. The summit occurs at a depth between 650 and 1500 m with the maximum depth reaching 4000 m (the abyssal bottom). The water masses, twists, eddies, and geomorphology favour the retention of nutrients and larvae, thus, being an area rich in nutrients. It is a hotspot of biodiversity and an important place for benthic communities. This study aims to inventory and review the asteroid fauna collected during the LIFE+INDEMARES project in GB, compare the new findings with previous studies Official Spanish Checklist (IEEM: "Inventario Español de Especies Marinas", Manjón-Cabeza et al. 2017, 2020) and update our knowledge of the diversity and distribution of known species. In this study a total of 272 asteroid specimens belonging to 19 species were found at 45 stations in depths between 765-1764 m, as part of the LIFE+INDEMARES-Galician Bank (2010-2011) surveys. The most frequently encountered species were Plinthaster dentatus (Perrier, 1884), Peltaster placenta (Müller & Troschel, 1842) and Henricia caudani (Koehler, 1895). Circeaster americanus (A.H. Clark, 1916) and Hymenaster giboryi (Perrier, 1894) are new observations from this area. For several species, including Henricia caudani, Pedicellaster typicus M. Sars, 1861, Podosphaeraster thalassae Cherbonnier, 1970 and Hymenaster giboryi known bathymetric range has been extended.

Many neurodegenerative diseases, including Huntington's disease (HD) and Alzheimer's disease (AD), occur due to an accumulation of aggregation-prone proteins, which results in neuronal death. Studies in animal and cell models show that reducing the levels of these proteins mitigates disease phenotypes. We previously reported a small molecule, NCT-504, which reduces cellular levels of mutant huntingtin (mHTT) in patient fibroblasts as well as mouse striatal and cortical neurons from an Hdh Q111 mutant mouse. Here, we show that NCT-504 has a broader potential, and in addition reduces levels of Tau, a protein associated with Alzheimer's disease, as well as other tauopathies. We find that in untreated cells, Tau and mHTT are degraded via autophagy. Notably, treatment with NCT-504 diverts these proteins to multivesicular bodies (MVB) and the ESCRT pathway. Specifically, NCT-504 causes a proliferation of endolysosomal organelles including MVB, and an enhanced association of mHTT and Tau with endosomes and MVB. Importantly, depletion of proteins that act late in the ESCRT pathway blocked NCT-504 dependent degradation of Tau. Moreover, NCT-504-mediated degradation of Tau occurred in cells where Atg7 is depleted, which indicates that this pathway is independent of canonical autophagy. Together, these studies reveal that upregulation of traffic through an ESCRT-dependent MVB pathway may provide a therapeutic approach for neurodegenerative diseases.

Increased brain iron content has been consistently reported in sporadic Parkinson's disease (PD) patients, and an increase in cytosolic free iron is known to cause oxidative stress and cell death. However, whether iron also accumulates in susceptible brain areas in humans or in mouse models of familial PD remains unknown. In addition, whilst the lysosome functions as a critical intracellular iron storage organelle, little is known about the mechanisms underlying lysosomal iron release and how this process is influenced by lysosome biogenesis and/or lysosomal exocytosis. Here, we report an increase in brain iron content also in PD patients due to the common G2019S-LRRK2 mutation as compared to healthy age-matched controls, whilst differences in iron content are not observed in G2019S-LRRK2 knockin as compared to control mice. Chemically triggering iron overload in cultured cells causes cytotoxicity via the endolysosomal release of iron which is mediated by TRPML1. TFEB expression reverts the iron overload-associated cytotoxicity by causing lysosomal exocytosis, which is dependent on a TRPML1-mediated increase in cytosolic calcium levels. Therefore, approaches aimed at increasing TFEB levels, or pharmacological TRPML1 activation in conjunction with iron chelation may prove beneficial against cell death associated with iron overload conditions such as those associated with PD., (© 2022. The Author(s).)

In the deep ocean symbioses between microbes and invertebrates are emerging as key drivers of ecosystem health and services. We present a large-scale analysis of microbial diversity in deep-sea sponges (Porifera) from scales of sponge individuals to ocean basins, covering 52 locations, 1077 host individuals translating into 169 sponge species (including understudied glass sponges), and 469 reference samples, collected anew during 21 ship-based expeditions. We demonstrate the impacts of the sponge microbial abundance status, geographic distance, sponge phylogeny, and the physical-biogeochemical environment as drivers of microbiome composition, in descending order of relevance. Our study further discloses that fundamental concepts of sponge microbiology apply robustly to sponges from the deep-sea across distances of >10,000 km. Deep-sea sponge microbiomes are less complex, yet more heterogeneous, than their shallow-water counterparts. Our analysis underscores the uniqueness of each deep-sea sponge ground based on which we provide critical knowledge for conservation of these vulnerable ecosystems., (© 2022. The Author(s).)

Phosphoinositide signaling lipids are crucial for eukaryotes and regulate many aspects of cell function. These signaling molecules are difficult to study because they are extremely low abundance. Here, we focus on two of the lowest abundance phosphoinositides, PI(3,5)P 2 and PI(5)P, which play critical roles in cellular homeostasis, membrane trafficking and transcription. Their levels are tightly regulated by a protein complex that includes PIKfyve, Fig4 and Vac14. Importantly, mutations in this complex that decrease PI(3,5)P 2 and PI(5)P are linked to human diseases, especially those of the nervous system. Paradoxically, PIKfyve inhibitors which decrease PI(3,5)P 2 and PI(5)P, are currently being tested for some neurodegenerative diseases, as well as other diverse diseases including some cancers, and as a treatment for SARS-CoV2 infection. A more comprehensive picture of the pathways that are regulated by PIKfyve will be critical to understand the roles of PI(3,5)P 2 and PI(5)P in normal human physiology and in disease., Competing Interests: Conflict of interest statement Nothing declared., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Sponges are amongst the most difficult benthic taxa to properly identify, which has led to a prevalence of cryptic species in several sponge genera, especially in those with simple skeletons. This is particularly true for sponges living in remote or hardly accessible environments, such as the deep-sea, as the inaccessibility of their habitat and the lack of accurate descriptions usually leads to misclassifications. However, species can also remain hidden even when they belong to genera that have particularly characteristic features. In these cases, researchers inevitably pay attention to these peculiar features, sometimes disregarding small differences in the other "typical" spicules. The genus Melonanchora Carter, 1874, is among those well suited for a revision, as their representatives possess a unique type of spicule (spherancorae). After a thorough review of the material available for this genus from several institutions, four new species of Melonanchora , M. tumultuosa sp. nov., M. insulsa sp. nov., M. intermedia sp. nov. and M. maeli sp. nov. are formally described from different localities across the Atlanto-Mediterranean region. Additionally, all Melonanchora from the Okhotsk Sea and nearby areas are reassigned to other genera; Melonanchora kobjakovae is transferred to Myxilla ( Burtonanchora ) while two new genera, Hanstoreia gen. nov. and Arhythmata gen. nov. are created to accommodate Melonanchora globogilva and Melonanchora tetradedritifera , respectively. Hanstoreia gen. nov. is closest to Melonanchora , whereas Arhythmata gen. nov., is closer to Stelodoryx , which is most likely polyphyletic and in need of revision., Competing Interests: The authors declare that they have no competing interests., (© 2021 Santín et al.)

The peripheral areas of deep-sea hydrothermal vents are often inhabited by an assemblage of animals distinct to those living close to vent chimneys. For many such taxa, it is considered that peak abundances in the vent periphery relate to the availability of hard substrate as well as the increased concentrations of organic matter generated at vents, compared to background areas. However, the peripheries of vents are less well-studied than the assemblages of vent-endemic taxa, and the mechanisms through which peripheral fauna may benefit from vent environments are generally unknown. Understanding this is crucial for evaluating the sphere of influence of hydrothermal vents and managing the impacts of future human activity within these environments, as well as offering insights into the processes of metazoan adaptation to vents. In this study, we explored the evolutionary histories, microbiomes and nutritional sources of two distantly-related sponge types living at the periphery of active hydrothermal vents in two different geological settings ( Cladorhiza from the E2 vent site on the East Scotia Ridge, Southern Ocean, and Spinularia from the Endeavour vent site on the Juan de Fuca Ridge, North-East Pacific) to examine their relationship to nearby venting. Our results uncovered a close sister relationship between the majority of our E2 Cladorhiza specimens and the species Cladorhiza methanophila , known to harbor and obtain nutrition from methanotrophic symbionts at cold seeps. Our microbiome analyses demonstrated that both E2 Cladorhiza and Endeavour Spinularia sp. are associated with putative chemosynthetic Gammaproteobacteria, including Thioglobaceae (present in both sponge types) and Methylomonaceae (present in Spinularia sp.). These bacteria are closely related to chemoautotrophic symbionts of bathymodiolin mussels. Both vent-peripheral sponges demonstrate carbon and nitrogen isotopic signatures consistent with contributions to nutrition from chemosynthesis. This study expands the number of known associations between metazoans and potentially chemosynthetic Gammaproteobacteria, indicating that they can be incredibly widespread and also occur away from the immediate vicinity of chemosynthetic environments in the vent-periphery, where these sponges may be adapted to benefit from dispersed vent fluids., (Copyright © 2020 Georgieva, Taboada, Riesgo, Díez-Vives, De Leo, Jeffreys, Copley, Little, Ríos, Cristobo, Hestetun and Glover.)

Mutations in the gene encoding leucine-rich repeat kinase 2 (LRRK2) cause familial Parkinson's disease, and sequence variations are associated with the sporadic form of the disease. LRRK2 phosphorylates a subset of RAB proteins implicated in secretory and recycling trafficking pathways, including RAB8A and RAB10. Another RAB protein, RAB29, has been reported to recruit LRRK2 to the Golgi, where it stimulates its kinase activity. Our previous studies revealed that G2019S LRRK2 expression or knockdown of RAB8A deregulate epidermal growth factor receptor (EGFR) trafficking, with a concomitant accumulation of the receptor in a RAB4-positive recycling compartment. Here, we show that the G2019S LRRK2-mediated EGFR deficits are mimicked by knockdown of RAB10 and rescued by expression of active RAB10. By contrast, RAB29 knockdown is without effect, but expression of RAB29 also rescues the pathogenic LRRK2-mediated trafficking deficits independently of Golgi integrity. Our data suggest that G2019S LRRK2 deregulates endolysosomal trafficking by impairing the function of RAB8A and RAB10, while RAB29 positively modulates non-Golgi-related trafficking events impaired by pathogenic LRRK2.

Mutations in the gene encoding for leucine-rich repeat kinase 2 (LRRK2) are associated with both familial and sporadic Parkinson's disease (PD). LRRK2 encodes a large protein comprised of a GTPase and a kinase domain. All pathogenic variants converge on enhancing LRRK2 kinase substrate phosphorylation, and distinct LRRK2 kinase inhibitors are currently in various stages of clinical trials. Although the precise pathophysiological functions of LRRK2 remain largely unknown, PD-associated mutants have been shown to alter various intracellular vesicular trafficking pathways, especially those related to endolysosomal protein degradation events. In addition, biochemical studies have identified a subset of Rab proteins, small GTPases required for all vesicular trafficking steps, as substrate proteins for the LRRK2 kinase activity in vitro and in vivo . Therefore, it is crucial to evaluate the impact of such phosphorylation on neurodegenerative mechanisms underlying LRRK2-related PD, especially with respect to deregulated Rab-mediated endolysosomal membrane trafficking and protein degradation events. Surprisingly, a significant proportion of PD patients due to LRRK2 mutations display neuronal cell loss in the substantia nigra pars compacta in the absence of any apparent α-synuclein-containing Lewy body neuropathology. These findings suggest that endolysosomal alterations mediated by pathogenic LRRK2 per se are not sufficient to cause α-synuclein aggregation. Here, we will review current knowledge about the link between pathogenic LRRK2, Rab protein phosphorylation and endolysosomal trafficking alterations, and we will propose a testable working model whereby LRRK2-related PD may present with variable LB pathology., (Copyright © 2020 Rivero-Ríos, Romo-Lozano, Fasiczka, Naaldijk and Hilfiker.)

Background: Lithistid demosponges, also known as rock sponges, are a polyphyletic group of sponges which are widely distributed. In the Northeast Atlantic (NEA), 17 species are known and the current knowledge on their distribution is mainly restricted to the Macaronesian islands. In the Mediterranean Sea, 14 species are recorded and generally found in marine caves., Methods: Lithistids were sampled in nine NEA seamounts during the scientific expeditions Seamount 1 (1987) and Seamount 2 (1993) organized by the MNHN of Paris. Collected specimens were identified through the analyses of external and internal morphological characters using light and scanning electron microscopy, and compared with material from various museum collections as well as literature records., Results: A total of 68 specimens were analysed and attributed to 17 species across two orders, seven families, and seven genera, representing new records of distribution. Ten of these species are new to science, viz. Neoschrammeniella inaequalis sp. nov., N. piserai sp. nov., N. pomponiae sp. nov., Discodermia arbor sp. nov., D. kellyae sp. nov., Macandrewia schusterae sp. nov., M. minima sp. nov., Exsuperantia levii sp. nov., Leiodermatium tuba sp. nov. and Siphonidium elongatus sp. nov., and are here described and illustrated. New bathymetric records were also found for D. ramifera , D. verrucosa and M. robusta . The Meteor seamount group has a higher species richness (15 species) compared to the Lusitanian seamount group (six species). The majority of the species had their distribution restricted to one seamount, and ten are only known from a single locality, but this can be a result of sample bias., Discussion: The number of species shared between the seamounts and the Macaronesian islands is very reduced. The same pattern repeats between the NEA and Mediterranean Sea. This study demonstrates that NEA seamounts are ecosystems with a higher diversity of lithistids than previously thought, increasing the number of lithistids known to occur in the NEA and Mediterranean Sea from 26 to 36 species., Competing Interests: The authors declare that they have no competing interests., (© 2020 Carvalho et al.)

Mutations in the gene encoding for leucine-rich repeat kinase 2 (LRRK2) are a common cause of hereditary Parkinson's disease. LRRK2 regulates various intracellular vesicular trafficking pathways, including endolysosomal degradative events such as epidermal growth factor receptor (EGFR) degradation. Recent studies have revealed that a subset of RAB proteins involved in secretory and endocytic recycling are LRRK2 kinase substrates in vivo However, the effects of LRRK2-mediated phosphorylation of these substrates on membrane trafficking remain unknown. Here, using an array of immunofluorescence and pulldown assays, we report that expression of active or phosphodeficient RAB8A variants rescues the G2019S LRRK2-mediated effects on endolysosomal membrane trafficking. Similarly, up-regulation of the RAB11-Rabin8-RAB8A cascade, which activates RAB8A, also reverted these trafficking deficits. Loss of RAB8A mimicked the effects of G2019S LRRK2 on endolysosomal trafficking and decreased RAB7A activity. Expression of pathogenic G2019S LRRK2 or loss of RAB8A interfered with EGFR degradation by causing its accumulation in a RAB4-positive endocytic compartment, which was accompanied by a deficit in EGFR recycling and was rescued upon expression of active RAB7A. Dominant-negative RAB7A expression resulted in similar deficits in EGF degradation, accumulation in a RAB4 compartment, and deficits in EGFR recycling, which were all rescued upon expression of active RAB8A. Taken together, these findings suggest that, by impairing RAB8A function, pathogenic G2019S LRRK2 deregulates endolysosomal transport and endocytic recycling events., (© 2019 Rivero-Ríos et al.)

Artemisina Vosmaer, 1885 is a poecilosclerid microcionoid sponge genus with 20 valid species, seven of which have been recorded in the Atlantic Ocean.The present study describes Artemisina sponge grounds in Iberia Peninsula. A. transiens is a sponge described in 1890 by Topsent in Galicia (Spain); A. hispanica was also collected in the north of Spain by Ferrer-Hernández (1917); World Porifera Database (WPD) considers at the moment both mushroom-shaped species as synonyms (van Soest et al., 2018), but we have only been able to check the types of A. hispanica. The studied samples were collected in Somos Llungo station and they correspond clearly to those described as A. hispanica by Ferrer-Hernández (1917) and it presents differences in the skeleton with respet to description of A. transiens in the literture. There are no more records after 1917 and there are no data of ecological characterisation nor is there a detailed description of its skeletal composition with Scanning Electron Microscopy. In the previous records the formation of sponge grounds of these species was not known.                                                                                                                          Oceana, the largest international organization focused solely on protecting the world's oceans, has recorded the habitat of Artemisina in Atlantic and Cantabrian waters during a series of ROV cruises for the identification of marine areas with high ecological value that need protection. Its life conditions and associated fauna are described from direct observations for the first time.

This study describes a new species of carnivorous sponge (Family Cladorhizidae) collected in Patagonia, SW Atlantic, off Argentinean waters and the North of the Falkland Islands (Malvinas). The species described here, belongs to the genus Abyssocladia and was collected by dredging and trawling during IEO (Spanish Institute of Oceanography) cruises in the South West Atlantic Ocean from 2007 to 2010 under the Atlantis Project. Abyssocladia vaceleti sp. nov. is characterised by the possession of a long peduncle and flat body with bilaterally symmetrical and apical filaments with a skeleton of tornotes (often polytylotes), styles, abyssochelae, arcuate chelae, sigmancistras and acanthotylostrongyles. This species lives at depths of 901-1547 m.

Sponges are a dominant element of the Antarctic benthic communities, posing both high species richness and large population densities. Despite their importance in Antarctic ecosystems, very little is known about their reproductive patterns and strategies. In our study, we surveyed the tissue of six different species for reproductive elements, namely, Dendrilla antarctica Topsent, 1905 (order Dendroceratida), Phorbas areolatus (Thiele, 1905), Kirkpatrickia variolosa (Kirkpatrick, 1907), and Isodictya kerguelenensis (Ridley & Dendy, 1886) (order Poecilosclerida), and Hemigellius pilosus (Kirkpatrick, 1907) and Haliclona penicillata (Topsent, 1908) (Haplosclerida). Samples of these six species containing various reproductive elements were collected in Deception Island and were processed for both light and transmission electron microscopy (TEM). Even though we were not able to monitor the entire reproductive cycle, due to time and meteorological conditions, we report important aspects of the reproduction of these species. This includes oocyte and embryo morphology and cell ultrastructure, follicular structures and nurse cell activity, as well as vitellogenesis. All species were brooding their embryos within their mesohyl. Both oocytes and embryos were registered in the majority of the studied species, and a single sperm cell being carried to an egg for fertilization was observed in H. penicillata. While the reproductive periods of all species coincided temporally, some of them seemed to rely on a single spawning event, this being suggested by the synchronic oogenesis and embryogenesis occurrence of D. antarctica, P. areolatus and I. kerguelenensis. In contrast, K. variolosa had an asynchronous embryo development, which suggests several larval release events. Our results suggest that differences in the reproductive strategies and morphological traits might succeed in the coexistence of these species at the same habitat avoiding the direct competition between them.

Leucine-rich repeat kinase 2 (LRRK2) is a key player in the pathogenesis of Parkinson's disease. Mutations in LRRK2 are associated with increased kinase activity that correlates with cytotoxicity, indicating that kinase inhibitors may comprise promising disease-modifying compounds. However, before embarking on such strategies, detailed knowledge of the cellular deficits mediated by pathogenic LRRK2 in the context of defined and pathologically relevant kinase substrates is essential. LRRK2 has been consistently shown to impair various intracellular vesicular trafficking events, and recent studies have shown that LRRK2 can phosphorylate a subset of proteins that are intricately implicated in those processes. In light of these findings, we here review the link between cellular deficits in intracellular trafficking pathways and the LRRK2-mediated phosphorylation of those newly identified substrates., (© 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.)

Two-pore channels are endolysosomal Ca 2+ release channels involved in proper trafficking to and from those organelles. They are the likely targets for the Ca 2+ -mobilizing messenger NAADP, and are further regulated by a variety of mechanisms including phosphoinositide levels and Rab proteins. As discussed here, recent studies highlight a role for these channels in the pathomechanism(s) underlying Parkinson's disease, with important implications for possible alternative treatment strategies.

Carnivorous sponges are characterized by their unique method of capturing mesoplanktonic prey coupled with the complete or partial reduction of the aquiferous system characteristic of the phylum Porifera. Current systematics place the vast majority of carnivorous sponges within Cladorhizidae, with certain species assigned to Guitarridae and Esperiopsidae. Morphological characters have not been able to show whether this classification is evolutionary accurate, and whether carnivory has evolved once or in several lineages. In the present paper we present the first comprehensive molecular phylogeny of the carnivorous sponges, interpret these results in conjunction with morphological characters, and propose a revised classification of the group. Molecular phylogenies were inferred using 18S rDNA and a combined dataset of partial 28S rDNA, COI and ALG11 sequences. The results recovered carnivorous sponges as a clade closely related to the families Mycalidae and Guitarridae, showing family Cladorhizidae to be monophyletic and also including carnivorous species currently placed in other families. The genus Lycopodina is resurrected for species currently placed in the paraphyletic subgenus Asbestopluma (Asbestopluma) featuring forceps spicules and lacking sigmas or sigmancistras. The genera Chondrocladia and Cladorhiza are found to be monophyletic. However, results indicate that the subgenus Chondrocladia is polyphyletic with respect to the subgenera Meliiderma and Symmetrocladia. Euchelipluma, formerly Guitarridae, is retained, but transferred to Cladorhizidae. The four known carnivorous species currently in Esperiopsis are transferred to Abyssocladia. Neocladia is a junior homonym and is here renamed Koltunicladia. Our results provide strong evidence in support of the hypothesis that carnivory in sponges has evolved only once. While spicule characters mostly reflect monophyletic groups at the generic level, differences between genera represent evolution within family Cladorhizidae rather than evolution of carnivory in separate lineages. Conflicting spicule characters can be reinterpreted to support the inclusion of all carnivorous sponges within Cladorhizidae, and a carnivorous habit should thus be considered the main diagnostic character in systematic classification., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Autophagy is a cellular quality control mechanism crucial for neuronal homeostasis. Defects in autophagy are critically associated with mechanisms underlying Parkinson's disease (PD), a common and debilitating neurodegenerative disorder. Autophagic dysfunction in PD can occur at several stages of the autophagy/lysosomal degradative machinery, contributing to the formation of intracellular protein aggregates and eventual neuronal cell death. Therefore, autophagy inducers may comprise a promising new therapeutic approach to combat neurodegeneration in PD. Several currently available FDA-approved drugs have been shown to enhance autophagy, which may allow for their repurposing for use in novel clinical conditions including PD. This review summarizes our current knowledge of deficits in the autophagy/lysosomal degradation pathways associated with PD, and highlight current approaches which target this pathway as possible means towards novel therapeutic strategies.

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene comprise the most common cause of familial Parkinson's disease (PD), and variants increase the risk for sporadic PD. LRRK2 displays kinase and GTPase activity, and altered catalytic activity correlates with neurotoxicity, making LRRK2 a promising therapeutic target. Despite the importance of LRRK2 for disease pathogenesis, its normal cellular function, and the mechanism(s) by which pathogenic mutations cause neurodegeneration remain unclear. LRRK2 seems to regulate a variety of intracellular vesicular trafficking events to and from the late endosome in a manner dependent on various Rab proteins. At least some of those events are further regulated by LRRK2 in a manner dependent on two-pore channels (TPCs). TPCs are ionic channels localized to distinct endosomal structures and can cause localized calcium release from those acidic stores, with downstream effects on vesicular trafficking. Here, we review current knowledge about the link between LRRK2, TPC- and Rab-mediated vesicular trafficking to and from the late endosome, highlighting a possible cross-talk between endolysosomal calcium stores and Rab proteins underlying pathomechanism(s) in LRRK2-related PD.

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene cause late-onset autosomal dominant Parkinson's disease (PD), and sequence variations at the LRRK2 locus are associated with increased risk for sporadic PD. LRRK2 contains both GTPase and kinase domains flanked by protein interaction motifs, and mutations associated with familial PD have been described for both catalytic domains. LRRK2 has been implicated in diverse cellular processes, and recent evidence pinpoints to an important role for LRRK2 in modulating a variety of intracellular membrane trafficking pathways. However, the underlying mechanisms are poorly understood. Here, by studying the classical, well-understood, degradative trafficking pathway of the epidermal growth factor receptor (EGFR), we show that LRRK2 regulates endocytic membrane trafficking in an Rab7-dependent manner. Mutant LRRK2 expression causes a slight delay in early-to-late endosomal trafficking, and a pronounced delay in trafficking out of late endosomes, which become aberrantly elongated into tubules. This is accompanied by a delay in EGFR degradation. The LRRK2-mediated deficits in EGFR trafficking and degradation can be reverted upon coexpression of active Rab7 and of a series of proteins involved in bridging the EGFR to Rab7 on late endosomes. Effector pulldown assays indicate that pathogenic LRRK2 decreases Rab7 activity both in cells overexpressing LRRK2, as well as in fibroblasts from pathogenic mutant LRRK2 PD patients when compared with healthy controls. Together, these findings provide novel insights into a previously unknown regulation of Rab7 activity by mutant LRRK2 which impairs membrane trafficking at very late stages of the endocytic pathway., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Parkinson's disease (PD) is a major health problem affecting millions of people worldwide. Recent studies provide compelling evidence that altered Ca(2) (+) homeostasis may underlie disease pathomechanism and be an inherent feature of all vulnerable neurons. The downstream effects of altered Ca(2) (+) handling in the distinct subcellular organelles for proper cellular function are beginning to be elucidated. Here, we summarize the evidence that vulnerable neurons may be exposed to homeostatic Ca(2) (+) stress which may determine their selective vulnerability, and suggest how abnormal Ca(2) (+) handling in the distinct intracellular compartments may compromise neuronal health in the context of aging, environmental, and genetic stress. Gaining a better understanding of the varied effects of Ca(2) (+) dyshomeostasis may allow novel combinatorial therapeutic strategies to slow PD progression.

Hexactinellids (glass sponges) are an understudied class with syncytial organization and poor procariotic associations, thought to lack defensive secondary metabolites. Poriferans, though, are outstanding sources of bioactive compounds; nonetheless, a growing suspicion suggests that many of these chemicals could be symbiont-derived. In Polar latitudes, sponges are readily invaded by diatoms, which could provide natural products. Hexactinellids are typical of deep waters; but in Antarctica, they dominate the upper shelf providing shelter and food supply to many opportunistic mesograzers and macroinvertebrates, which exert strong ecological pressures on them. Aiming to examine the incidence of defensive activities of hexactinellids against consumption, feeding experiments were conducted using their lipophilic fractions. Antarctic hexactinellid and demosponge extracts were tested against the asteroid Odontaster validus and the amphipod Cheirimedon femoratus as putative sympatric, omnivorous consumers. Hexactinellids yielded greater unpalatable activities towards the amphipod, while no apparent allocation of lipophilic defenses was noted. After chemical analyses on the lipophilic fractions from these Antarctic glass sponges, quite similar profiles were revealed, and no peculiar secondary metabolites, comparable to those characterizing other poriferans, were found. Instead, the lipidic compounds 5α(H)-cholestan-3-one and two glycoceramides were isolated for their particular outspread presence in our samples. The isolated compounds were further assessed in asteroid feeding assays, and their occurrence was evaluated for chemotaxonomical purposes in all the Antarctic samples as well as in glass sponges from other latitudes by NMR and MS. Characteristic sphingolipids are proposed as chemical markers in Hexactinellida, with possible contributions to the classification of this unsettled class.

Background: Hepatitis delta virus (HDV) has a unique replication process that requires coinfection with hepatitis B virus (HBV). Treatment is currently limited to interferon therapy. The role of potent nucleos(t)ide analogues active against HBV has not been well examined in chronic delta hepatitis (CDH)., Methods: HIV-positive patients with CDH attending our hospital were identified and longitudinally studied. Serum HBV DNA, HDV RNA and HIV RNA, treatment regimens, and biochemical and serological markers were assessed at yearly intervals. Liver fibrosis was measured by transient elastography during the last 2 years., Results: Sixteen patients were identified and treated with anti-HBV therapy (median time 6.1 years). The majority were male and previous intravenous drug users. Median baselines were: HDV RNA 7 log10 copies/ml, HIV RNA 1.7 log10 copies/ml, HBV DNA 1.1 log10 IU/ml and alanine aminotransferase (ALT) 98 IU/ml. A significant correlation was found between HDV RNA and HBV DNA (r=0.226, P=0.015), aspartate aminotransferase (r=0.430, P<0.0001), ALT (r=0.441, P<0.0001) and hepatitis B surface antigen (HBsAg) (r=0.557, P<0.0001). Overall, 13 patients showed a reduction in HDV viraemia and ALT levels, and three of them achieved undetectable HDV RNA and normal ALT levels., Conclusion: Patients undergoing successful anti-HBV therapy with potent nucleos(t)ide analogues seem to indirectly benefit from suppression of HDV replication, albeit not very efficiently. Hypothetically, a significant and sustained reduction in serum HDV RNA might only be seen when a reduction in HBV covalently closed circular DNA or HBV surface antigen is achieved, which may require long periods of successful anti-HBV therapy. To our knowledge, this is the first evidence of the benefit of potent anti-HBV nucleos(t)ide analogue therapy in CDH.

Background: Changes in the prevalence of distinct hepatitis C virus (HCV) genotypes and subtypes over time have not been explored in detail., Methods: A retrospective analysis was carried out in all specimens from subjects with chronic hepatitis C sent for testing to a reference laboratory in Spain since 1998-2004., Results: A total of 1226 distinct subjects were analyzed. The most frequent HCV genotype was 1 (64.1%), followed by 3 (20.9%) and 4 (11.7%). The most frequent HCV subtype was 1b (32.4%). A total of 797 patients (65%) were HIV-positive. Although genotype 1 was the most frequent, it represented 74.6% of HIV-negative and 58.5% of HIV-positive patients (p<0.01). While HCV subtype 1a was the most frequent among HIV-positive subjects (32.1%), 1b was the most common in HIV-negative patients (53.8%). There was a significant increase in the prevalence of genotype 4 and conversely a decline in genotype 3 among HIV-positive patients over time., Conclusion: Genotype 1 is the most frequent HCV variant circulating in Spain. Genotypes 3 and 4 are significantly more prevalent in HIV/HCV-coinfected than in HCV-monoinfected patients. However, HCV-3 has declined and HCV-4 is increasing in the former group. These findings are relevant given their different susceptibility to interferon-based therapies.

Purpose: A cross-sectional study was performed during 2004 at a large HIV clinic in Spain to identify HIV-HCV coinfected individuals who might be candidates for HCV therapy., Method: Plasma HCV RNA levels were measured in 405 anti-HCV antibody positive patients. Spontaneous HCV clearance had occurred in 11.4%. Overall, 165 (40.1%) of HCV-HIV coinfected patients had already been exposed to interferon (IFN)-based therapies. Excluding those currently on treatment, the majority of them had either failed (64/142; 45.1%) or not completed therapy (25/142; 17.6%). Other 103 (25.4%) chronic HCV carriers refused treatment or were not considered as appropriate candidates, most often due to low CD4 counts or severe neuropsychiatric conditions. Treatment was deemed feasible and planned in the near future in 91 (22.5%) patients. Unfavorable HCV genotypes (1 and 4) were significantly more frequent in this group of individuals ready for HCV treatment compared to those who had cleared HCV in the past following IFN-based therapies., Results: Spontaneous clearance of the HCV infection was low in HIV-coinfected patients. One third of our HIV-HCV coinfected population had already been exposed to HCV therapy, but only a minority had achieved sustained HCV clearance. Half of patients with active HCV replication never exposed to IFN were not considered as appropriate candidates for HCV therapy., Conclusion: More flexible criteria would considerably increase the number of patients to be treated with IFN-based therapy. The majority of patients ready to initiate HCV therapy have a poor therapeutic profile.

Background: Atazanavir (ATV) is the latest approved HIV protease inhibitor (PI). Even though it is very convenient (only two capsules once a day), concerns have risen about its potency., Method: The clinical performance of ATV 400 mg once a day was examined in all PI-experienced patients who were included in the ATV expanded access program conducted in a single institution. The predictive value of baseline drug resistance HIV genotypes, ATV plasma trough levels, and the genotypic inhibitory quotient (GIQ) on the virological response at week 24 was assessed., Results: Data from 92 patients were analyzed. ATV was prescribed as part of a rescue intervention (45%), a simplification strategy (11%), or an attempt to ameliorate hyperlipidemias (23%) or other toxicities (16%). Tenofovir (TDF) was concomitantly used with ATV in 78% of patients. None received ritonavir boosting. In patients with detectable viremia at baseline (65%), the median HIV RNA drop was 0.7 logs. The median ATV Cmin was 0.12 microg/mL (IQR, 0.05-0.22 microg/mL), which is clearly above the IC90 (90% inhibitory concentration) for ATV in wild-type viruses. The virological response did not correlate significantly with ATV Cmin. The median number of protease resistance mutations was lower in patients showing virological response than in nonresponders (1 vs. 5; p=.07). A higher HIV RNA drop was associated with a higher GIQ (p=.02; beta=-5.4; 95% CI, -10 to -1). Only 4 patients (4%) discontinued treatment due to ATV-related toxicities (hyperbilirubinemia in 1). Bilirubin levels were associated with ATV plasma concentrations (p=.05; beta=3.2; 95% CI, -0.1 to 6.5). The rate of hypertriglyceridemia and hypercholesterolemia declined significantly with respect to baseline., Conclusion: ATV is relatively safe and provides significant virological response in PI-experienced patients, mainly among those with a low number of protease resistance mutations. The GIQ predicts accurately the virological response in patients receiving ATV. Hyperbilirubinemia is associated with higher ATV plasma levels.

The response to standard or pegylated interferon (IFN) plus ribavirin (RBV) seems to be lower in hepatitis C virus (HCV)/HIV-coinfected subjects than in HCV-monoinfected patients. Thus, the principles guiding anti-HCV therapy in HIV-negative patients may not apply in the setting of HIV infection. We examined the rate of HCV relapse in 58 HCV/HIV-coinfected subjects who showed undetectable HCV-RNA (<600 IU/ml) at the end of anti-HCV combination therapy. Overall, 19 (32.8%) patients relapsed after discontinuing treatment, a rate significantly higher than that seen in HIV negatives, which is in the range of 15-20%. There were no significant differences between HCV genotypes (33.3% for HCV genotypes 2-3 versus 31.8% for HCV genotypes 1-4) and/or the use of either standard or pegylated IFN (37% versus 29%, respectively). Thus, extended periods of anti-HCV therapy might reduce HCV relapses in HIV-coinfected patients initially responding to therapy.

Hepatitis B virus (HBV) genotypes were examined in HIV-infected patients with chronic HBV infection seen in our clinic during 2002. A total of 28 of 1100 individuals (prevalence 2.5%) were found to be HBsAg and HBV-DNA positive. HBV genotypes could be determined in 23 of them. HBV-A was the most common (57%), followed by HBV-D (39%). HBV-A predominated among homosexual men (67%) while HBV-D predominated among intravenous drug users (67%). The presence of serum HBeAg was significantly associated with the HBV-A genotype.

Treatment of hepatitis B virus (HBV) with lamivudine may not completely suppress viral replication and often fails as a result of lamivudine resistance. Tenofovir is a new HIV inhibitor with further activity against HBV, which was explored in 12 HBV/HIV-co-infected patients with detectable levels of serum HBV-DNA, despite receiving a lamivudine-containing antiretroviral regimen. Lamivudine-resistance mutations were found in HBV from seven patients. HBV-DNA levels dropped a median of 3.78 logs from baseline to 24 weeks. Tenofovir was very effective at reducing HBV-DNA levels in HIV/HBV-co-infected patients carrying either wild-type or lamivudine-resistant viruses.

Objective: To assess the role of different hepatitis C virus (HCV) genotypes in the development of transaminase elevation after treatment with highly active antiretroviral therapy (HAART)., Design: Retrospective cohort study at one referral HIV outpatient clinic., Methods: HCV genotype was determined in plasma samples from all consecutive HCV-HIV coinfected patients initiating HAART between March 1998 and January 2000. Clinical and laboratory data were recorded during the following 9 months. Severe transaminase elevation was defined as > or = fivefold increase over upper normal limits (AIDS Clinical Trials Group grades 3 or 4) when baseline alanine transaminase (ALT) and aspartate transaminase (AST) values were normal, and as > or = 3.5-fold increase above baseline ALT and AST values if they were abnormal., Results: Twelve of 70 subjects (17%) developed severe transaminase elevation. Their HCV genotypes were distributed as follows: type 1, 5/39 (13%); type 2, 0/3 (0%); type 3, 7/21 (33%); and type 4, 0/7 (0%). The incidence of severe transaminase elevation was significantly higher among subjects with HCV genotype 3 (HCV-3) compared with those with non-type 3 (OR, 4.4 [95%CI, 1.2-16.1]; P =.02). In the multivariate analysis, HCV-3 remained associated with severe transaminase elevation when adjusted for baseline HCV viral load and degree of immune recovery seen during follow-up evaluation., Conclusions: HCV-3 is an independent risk factor for developing severe transaminase elevation after HAART. HCV genotyping before initiating antiretroviral therapy may be useful for assessing the risk of hepatotoxicity and for choosing the most appropriate drugs to prescribe for HIV-HCV coinfected patients. Given that the best response to interferon plus ribavirin occurs in patients with HCV-3, treatment should be specially encouraged in coinfected persons carrying HCV-3.