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For more than a decade numerous evidence has been reported on the mechanisms of toxicity of α-synuclein (αS) oligomers and aggregates in α-synucleinopathies. These species were thought to form freely in the cytoplasm but recent reports of αS multimer conformations when bound to synaptic vesicles in physiological conditions, have raised the question about where αS aggregation initiates. In this review we focus on recent literature regarding the impact on membrane binding and subcellular localization of αS toxic species to understand how regular cellular function of αS contributes to pathology. Notably αS has been reported to mainly associate with specific membranes in neurons such as those of synaptic vesicles, ER/Golgi and the mitochondria, while toxic species of αS have been shown to inhibit, among others, neurotransmission, protein trafficking and mitochondrial function. Strategies interfering with αS membrane binding have shown to improve αS-driven toxicity in worms and in mice. Thus, a selective membrane binding that would result in a specific subcellular localization could be the key to understand how aggregation and pathology evolves, pointing out to αS functions that are primarily affected before onset of irreversible damage.

Aquaporin-5 (AQP5) is selectively expressed in the apical membrane of exocrine glands, such as salivary, lacrimal, and submucosal glands. It is important for the secretory function of exocrine glands because mice with the knockout of AQP5 exhibit a significant reduction in secretion from these glands. Previous reports indicated that the AQP5 C-terminal domain is crucial for the localization of AQP5 at the plasma membrane, but it remains unclear which motif or amino acid residues in the C-terminal domain are essential for this. In this study, we examined the effects of various AQP5 C-terminal deletions or mutations on the expression of AQP5 on the cell surface. AQP5 C-terminal domain mutants did not localize on the plasma membrane, and Leu262 was shown to be crucial for AQP5′s plasma membrane localization. The mutants localized in the autophagosome or lysosome and showed decreased protein stability via lysosomal degradation. Taking these findings together, our study suggests that the C-terminal domain is required for AQP5 to pass protein quality control and be trafficked to the plasma membrane.

Verticillium wilt caused by Verticillium dahliae is a notorious soil-borne fungal disease and seriously threatens the yield of economic crops worldwide. During host infection, V. dahliae secretes many effectors that manipulate host immunity, among which small cysteine-rich proteins (SCPs) play an important role. However, the exact roles of many SCPs from V. dahliae are unknown and varied. In this study, we show that the small cysteine-rich protein VdSCP23 inhibits cell necrosis in Nicotiana benthamiana leaves, as well as the reactive oxygen species (ROS) burst, electrolyte leakage and the expression of defense-related genes. VdSCP23 is mainly localized in the plant cell plasma membrane and nucleus, but its inhibition of immune responses was independent of its nuclear localization. Site-directed mutagenesis and peptide truncation showed that the inhibition function of VdSCP23 was independent of cysteine residues but was dependent on the N-glycosylation sites and the integrity of VdSCP23 protein structure. Deletion of VdSCP23 did not affect the growth and development of mycelia or conidial production in V. dahliae. Unexpectedly, VdSCP23 deletion strains still maintained their virulence for N. benthamiana, Gossypium hirsutum and Arabidopsis thaliana seedlings. This study demonstrates an important role for VdSCP23 in the inhibition of plant immune responses; however, it is not required for normal growth or virulence in V. dahliae.

Anhydrobiosis, an adaptive ability to withstand complete desiccation, in the nonbiting midge Polypedilum vanderplanki, is associated with the emergence of new multimember gene families, including a group of 27 genes of late embryogenesis abundant (LEA) proteins (PvLea). To obtain new insights into the possible functional specialization of these genes, we investigated the expression and localization of PvLea genes in a P. vanderplanki-derived cell line (Pv11), capable of anhydrobiosis. We confirmed that all but two PvLea genes identified in the genome of P. vanderplanki are expressed in Pv11 cells. Moreover, PvLea genes are induced in Pv11 cells in response to anhydrobiosis-inducing trehalose treatment in a manner highly similar to the larvae of P. vanderplanki during the real induction of anhydrobiosis. Then, we expanded our previous data on PvLEA proteins localization in mammalian cells that were obtained using C-terminal fusions of PvLEA proteins and green fluorescent protein (GFP). We investigated PvLEA localization using N- and C-terminal fusions with GFP in Pv11 cells and the Sf9 insect cell line. We observed an inconsistency of PvLEA localization between different fusion types and different cell cultures, that needs to be taken into account when using PvLEA in the engineering of anhydrobiotic cell lines.

Yin Yang 1 (YY1) is a multi-functional transcription factor that regulates gene expression in a range of cell types, including neurons. It controls neuronal differentiation, as well as neuronal specification and migration during the development of the mammalian nervous system. Besides, YY1 also mediates the transcription of genes that are required for neuronal survival. An impairment of the transcriptional function of YY1 causes neuronal death. This review summarizes recent research findings that unveil the dysfunction of YY1 in multiple neurodegenerative disorders. The expression of disease proteins perturbs the function of YY1 via distinct molecular mechanisms, including recruitment to protein aggregates, protein degradation and aberrant nuclear/cytoplasmic shuttling. Understanding the pathogenic roles of YY1 will further broaden our knowledge of the disease mechanisms in distinct neurodegenerative disorders.

High mobility group box-1 (HMGB1), a nonhistone chromatin DNA-binding protein, is released from neurons into the extracellular space under ischemic, hemorrhagic, and traumatic insults. However, the details of the time-dependent translocation of HMGB1 and the subcellular localization of HMGB1 through the release process in neurons remain unclear. In the present study, we examined the subcellular localization of HMGB1 during translocation of HMGB1 in the cytosolic compartment using a middle cerebral artery occlusion and reperfusion model in rats. Double immunofluorescence microscopy revealed that HMGB1 immunoreactivities were colocalized with MTCO1(mitochondrially encoded cytochrome c oxidase I), a marker of mitochondria, and catalase, a marker of peroxisomes, but not with Rab5/Rab7 (RAS-related GTP-binding protein), LC3A/B (microtubule-associated protein 1 light chain 3), KDEL (KDEL amino acid sequence), and LAMP1 (Lysosomal Associated Membrane Protein 1), which are endosome, phagosome, endoplasmic reticulum, and lysosome markers, respectively. Immunoelectron microscopy confirmed that immune-gold particles for HMGB1 were present inside the mitochondria and peroxisomes. Moreover, HMGB1 was found to be colocalized with Drp1 (Dynamin-related protein 1), which is involved in mitochondrial fission. These results revealed the specific subcellular localization of HMGB1 during its release process under ischemic conditions.

The phospholipase A2 (PLA2) superfamily of phospholipase enzymes hydrolyzes the ester bond at the sn-2 position of the phospholipids, generating a free fatty acid and a lysophospholipid. The PLA2s are amphiphilic in nature and work only at the water/lipid interface, acting on phospholipid assemblies rather than on isolated single phospholipids. The superfamily of PLA2 comprises at least six big families of isoenzymes, based on their structure, location, substrate specificity and physiologic roles. We are reviewing the secreted PLA2 (sPLA2), cytosolic PLA2 (cPLA2), Ca2+-independent PLA2 (iPLA2), lipoprotein-associated PLA2 (LpPLA2), lysosomal PLA2 (LPLA2) and adipose-tissue-specific PLA2 (AdPLA2), focusing on the differences in their structure, mechanism of action, substrate specificity, interfacial kinetics and tissue distribution. The PLA2s play important roles both physiologically and pathologically, with their expression increasing significantly in diseases such as sepsis, inflammation, different cancers, glaucoma, obesity and Alzheimer’s disease, which are also detailed in this review.

Lipoxygenases (LOXs) are enzymes involved in lipid peroxidation. Here we reported the identification, molecular and functional characterization of the gene encoding rice (Oryza sativa L.) seed LOX3 (sLOX3). Via a map-based cloning strategy we identified Os03g0700400 as the candidate gene encoding sLOX3. Further functional complementary test and biochemical characterization of the recombinant Os03g0700400 protein verified the identification. The sLOX3 gene was highly expressed in roots, moderately in embryos and very weakly in leaves, leaf sheaths and stems. Transient expression experiment (in rice protoplasts) and subsequent laser confocal microscopic analysis demonstrated that the sLOX3 protein was localized into the cytosol. We next showed that overexpression of sLOX3 in a japonica sLOX3-normal rice cultivar, Wuyunjing 7 accelerated the decrease of seed germination ability when the seeds were routinely stored, which demonstrated that sLOX3 had a negative effect on seed longevity (storability). Meanwhile, an increased occurrence of embryo decay was observed in the same transgenic seeds, suggesting that sLOX3 might negatively affect seed longevity by facilitating colonization of particular seed pathogens. Our result forwarded the understanding of the effects of 9-LOX on rice seed longevity.

Subcellular localization critically influences protein function, and cells control protein localization to regulate biological processes. We have developed and applied Dynamic Organellar Maps, a proteomic method that allows global mapping of protein translocation events. We initially used maps statically to generate a database with localization and absolute copy number information for over 8700 proteins from HeLa cells, approaching comprehensive coverage. All major organelles were resolved, with exceptional prediction accuracy (estimated at >92%). Combining spatial and abundance information yielded an unprecedented quantitative view of HeLa cell anatomy and organellar composition, at the protein level. We subsequently demonstrated the dynamic capabilities of the approach by capturing translocation events following EGF stimulation, which we integrated into a quantitative model. Dynamic Organellar Maps enable the proteome-wide analysis of physiological protein movements, without requiring any reagents specific to the investigated process, and will thus be widely applicable in cell biology. The interior of every cell is highly organised, and contains many compartments, called organelles, that are dedicated to specific roles. Proteins are the tools and machines of the cell, and each organelle has its own set of proteins that it requires to work correctly. Each cell contains ten or more organelles, and several thousand different types of proteins. The exact location of proteins in the cell is important; once we know what compartment a protein is in, it is easier to narrow down what it might be doing. The location of many proteins in a cell is unclear or simply not known. Moreover, since changing the location of a protein can change its activity, it is also important to be able to detect changes in the location of proteins under different circumstances, such as before and after drug treatment. Itzhak et al. set out to develop a method that reveals the locations of all the proteins in a cell at any given time. The resulting technique maps the location of most of the proteins in a human cancer cell line and, in addition, determines how many copies of each protein there are. Combining these two types of information produces a model of the cell’s architecture. Importantly, Itzhak et al. were able to compare such a model of the cell under normal circumstances to a model made after the cell had been stimulated with a growth factor. This revealed which proteins had changed location, identifying these proteins as important for the cell’s response to the growth factor. The new mapping method could be used in the future to analyse the anatomy of different cell types, such as nerve cells and cells of the immune system. Itzhak et al. also want to investigate the differences between healthy cells and cells from people with neurological disorders to understand how such diseases arise.

Over the past decades, research on cancer biology has focused on the involvement of protein-coding genes in cancer development. Long noncoding RNAs (lncRNAs), which are transcripts longer than 200 nucleotides that lack protein-coding potential, are an important class of RNA molecules that are involved in a variety of biological functions. Although the functions of a majority of lncRNAs have yet to be clarified, some lncRNAs have been shown to be associated with human diseases such as cancer. LncRNAs have been shown to contribute to many important cancer phenotypes through their interactions with other cellular macromolecules including DNA, protein and RNA. Here we describe the literature regarding the biogenesis and features of lncRNAs. We also present an overview of the current knowledge regarding the roles of lncRNAs in cancer from the view of various aspects of cellular homeostasis, including proliferation, survival, migration and genomic stability. Furthermore, we discuss the methodologies used to identify the function of lncRNAs in cancer development and tumorigenesis. Better understanding of the molecular mechanisms involving lncRNA functions in cancer is critical for the development of diagnostic and therapeutic strategies against tumorigenesis.