Circ-SNAP47 (hsa_circ_0016760) and miR-625-5p are regulators of WEE1 in regulation of chemoresistance, growth and invasion of DDP-tolerant NSCLC cells via ceRNA pathway.

Circular RNA-synaptosome associated protein 47 (circ-SNAP47; Hsa_circ_0016760) is oncogenic in non-small-cell lung cancer (NSCLC); however, its role is undescribed in cis-diamminedichloroplatinum II (DDP) resistance. We attempted to investigate its expression, role and mechanism in DDP-tolerant NSCLC. As a result, circ-SNAP47 expression was upregulated in human DDP-tolerant NSCLC tissues and cells, accompanied with WEE1 G2 checkpoint kinase (WEE1) upregulation and microRNA (miR)-625-5p downregulation. Functionally, interfering circ-SNAP47 and/or restoring miR-625-5p curbed the 50% inhibitory concentration of DDP, colony formation, cell proliferation and invasion, accompanied with apoptotic rate promotion and depressions of multidrug resistance (MDR) markers MDR1 and MRP1, anti-apoptosis protein Bcl-2, and pro-invasion protein MMP9. Notably, circ-SNAP47 interference suppressed xenograft tumor growth of DDP-tolerant NSCLC cells by elevating miR-625-5p and descending WEE1. Mechanistically, circ-SNAP47 directly targeted miR-625-5p, and miR-625-5p further targeted WEE1. Therefore, circ-SNAP47-miR-625-5p-WEE1 axis might participate in chemoresistance and progression of DDP-tolerant NSCLC.

SNAP47 Interacts with ATG14 to Promote VP1 Conjugation and CVB3 Propagation.

Coxsackievirus B3 (CVB3), an enterovirus (EV) in the family of Picornaviridae, is a global human pathogen for which effective antiviral treatments and vaccines are lacking. Previous research demonstrated that EV-D68 downregulated the membrane fusion protein SNAP47 (synaptosome associated protein 47) and SNAP47 promoted EV-D68 replication via regulating autophagy. In the current study, we investigated the interplay between CVB3 and cellular SNAP47 using HEK293T/HeLa cell models. We showed that, upon CVB3 infection, protein levels of SNAP47 decreased independent of the activity of virus-encoded proteinase 3C. We further demonstrated that the depletion of SNAP47 inhibited CVB3 infection, indicating a pro-viral function of SNAP47. Moreover, we found that SNAP47 co-localizes with the autophagy-related protein ATG14 on the cellular membrane fractions together with viral capsid protein VP1, and expression of SNAP47 or ATG14 enhanced VP1 conjugation. Finally, we revealed that disulfide interactions had an important role in strengthening VP1 conjugation. Collectively, our study elucidated a mechanism by which SNAP47 and ATG14 promoted CVB3 propagation through facilitating viral capsid assembly.

SPIB promotes anoikis resistance via elevated autolysosomal process in lung cancer cells.

Anoikis (detachment-induced cell death) is a specific type of programmed cell death which occurs in response to the loss of the correct extracellular matrix connections. Anoikis resistance is an important mechanism in cancer invasiveness and metastatic behavior. Autophagy, on the other hand, involves the degradation of damaged organelles and the recycling of misfolded proteins and intracellular components. However, the intersection of these two cellular responses in lung cancer cells has not been extensively studied. Here, we identified that upon matrix deprivation, the lymphocyte lineage-specific Ets transcription factor SPIB was activated and directly enhanced SNAP47 transcription in certain lung cancer cells. Loss of attachment-induced autophagy significantly increased anoikis resistance by SPIB activation. Consistent with this function, SPIB depletion by short hairpin RNA abrogated SNAP47 transcriptional activation upon matrix deprivation. Therefore, these data delineate an important role of SPIB in autophagy-mediated anoikis resistance in lung cancer cells. Accordingly, these findings suggest that manipulating SPIB-regulated pathways in vivo and evaluating the impact of anoikis resistance warrant further investigation. DATABASE: RNA sequencing and ChIP sequencing data are available in Gene Expression Omnibus database under the accession numbers GSE106592 and GSE125561, respectively.

The SNAP-25 Protein Family.

SNARE-complexes drive the fusion of membrane-bound vesicles with target membranes or with each other (homotypic fusion). The SNARE-proteins are subdivided into Qa, Qb, Qc and R-SNAREs depending on their position in the four-helical SNARE-bundle. Here, we review the SNAP-25 protein sub-family, which includes both the Qb and Qc SNARE-domains within a single protein. In vertebrates, this sub-family consists of SNAP-25, SNAP-23, SNAP-29 and SNAP-47, named for their apparent molecular weights. SNAP-25 and SNAP-23 are specialized for driving regulated exocytosis. SNAP-25 performs this function in the nervous system, and in neuroendocrine cells, where fast Ca2+-dependent triggering is required in order to synchronize release with an electrical signal, whereas SNAP-23 drives regulated exocytosis in most other cases that have been studied, e.g. platelet exocytosis or glucose transporter trafficking. SNAP-25 is regulated by alternative splicing, phosphorylation and by G-protein binding, and it regulates Ca2+-channels, neuronal survival and postsynaptic spine development. SNAP-23 is primarily regulated by phosphorylation within the linker connecting Qb to Qc. Cross-rescue experiments show that SNAP-25 and SNAP-23 can (at least partly) substitute for each other, whereas SNAP-29 and SNAP-47 cannot. SNAP-29 is present on intracellular membranes and performs functions in autophagosome-to-lysosome fusion, among others. An overlapping function for SNAP-47 was described; in addition, SNAP-47 mediates postsynaptic AMPA-receptor insertion. Overall, the presence of two SNARE-domains confers members of this family the ability to associate to different Qa and R-SNAREs and drive diverse membrane fusion reactions; one member of the family, SNAP-25, has been devoted entirely to Ca2+-triggered fusion and has taken on a number of additional, regulatory roles.

Oh, SNAP! How enteroviruses redirect autophagic traffic away from degradation.

Picornaviruses, one of the major causes of human diseases ranging from the common cold to acute flaccid paralysis, have a short cytosolic lifecycle that, in cultured cells, ends in cell lysis. For years, the prevailing model was that these viruses exit from cells exclusively through cell lysis. However, over the last several years it has become apparent that for some picornaviruses, a macroautophagy/autophagy-related pathway can result in release of virus particles wrapped in a membrane containing autophagic markers. It has been proposed that this enveloped release predominates within hosts, allowing cell-to-cell movement of virus while minimizing exposure to the immune system. One reason that picornaviruses induce the autophagy pathway is to provide membrane scaffolds for RNA replication complexes. Perhaps more importantly, acidified autophagosomes (known as amphisomes) provide havens for maturation of new viral particles into infectious viruses. In back-to-back papers recently published in Cell Reports, our labs investigated a basic question: if picornavirus particles are maturing inside amphisomes, then how are they avoiding the typical degradative fate of autophagic cargo and exiting the cell intact?

Enteroviruses Remodel Autophagic Trafficking through Regulation of Host SNARE Proteins to Promote Virus Replication and Cell Exit.

Enterovirus D68 (EV-D68) is a medically important respiratory plus-strand RNA virus of children that has been linked to acute flaccid myelitis. We have determined that EV-D68 induces autophagic signaling and membrane formation. Autophagy, a homeostatic degradative process that breaks down protein aggregates and damaged organelles, promotes replication of multiple plus-strand viruses. Induction of autophagic signals promotes EV-D68 replication, but the virus inhibits the downstream degradative steps of autophagy in multiple ways. EV-D68 proteases cleave a major autophagic cargo adaptor and the autophagic SNARE SNAP29, which reportedly regulates fusion between autophagosome to amphisome/autolysosome. Although the virus inhibits autophagic degradation, SNAP29 promotes virus replication early in infection. An orphan SNARE, SNAP47, is shown to have a previously unknown role in autophagy, and SNAP47 promotes the replication of EV-D68. Our study illuminates a mechanism for subversion of autophagic flux and redirection of the autophagic membranes to benefit EV-D68 replication.

Distinct Localization of SNAP47 Protein in GABAergic and Glutamatergic Neurons in the Mouse and the Rat Hippocampus.

Synaptosomal-associated protein of 47 kDa (SNAP47) isoform is an atypical member of the SNAP family, which does not contribute directly to exocytosis and synaptic vesicle (SV) recycling. Initial characterization of SNAP47 revealed a widespread expression in nervous tissue, but little is known about its cellular and subcellular localization in hippocampal neurons. Therefore, in the present study we applied multiple-immunofluorescence labeling, immuno-electron microscopy and in situ hybridization (ISH) and analyzed the localization of SNAP47 in pre- and postsynaptic compartments of glutamatergic and GABAergic neurons in the mouse and rat hippocampus. While the immunofluorescence signal for SNAP47 showed a widespread distribution in both mouse and rat, the labeling pattern was complementary in the two species: in the mouse the immunolabeling was higher over the CA3 stratum radiatum, oriens and cell body layer. In contrast, in the rat the labeling was stronger over the CA1 neuropil and in the CA3 stratum lucidum. Furthermore, in the mouse high somatic labeling for SNAP47 was observed in GABAergic interneurons (INs). On the contrary, in the rat, while most INs were positive, they blended in with the high neuropil labeling. ISH confirmed the high expression of SNAP47 RNA in INs in the mouse. Co-staining for SNAP47 and pre- and postsynaptic markers in the rat revealed a strong co-localization postsynaptically with PSD95 in dendritic spines of pyramidal cells and, to a lesser extent, presynaptically, with ZnT3 and vesicular glutamate transporter 1 (VGLUT1) in glutamatergic terminals such as mossy fiber (MF) boutons. Ultrastructural analysis confirmed the pre- and postsynaptic localization at glutamatergic synapses. Furthermore, in the mouse hippocampus SNAP47 was found to be localized at low levels to dendritic shafts and axon terminals of putative INs forming symmetric synapses, indicating that this protein could be trafficked to both post- and presynaptic sites in both major cell types. These results reveal divergent localization of SNAP47 protein in mouse and rat hippocampus indicating species- and cell type-specific differences. SNAP47 is likely to be involved in unique fusion machinery which is distinct from the one involved in presynaptic neurotransmitter release. Nonetheless, our data suggest that SNAP47 may be involved not only postsynaptic, but also in presynaptic function.

The Q-soluble N-Ethylmaleimide-sensitive Factor Attachment Protein Receptor (Q-SNARE) SNAP-47 Regulates Trafficking of Selected Vesicle-associated Membrane Proteins (VAMPs).

SNAREs constitute the core machinery of intracellular membrane fusion, but vesicular SNAREs localize to specific compartments via largely unknown mechanisms. Here, we identified an interaction between VAMP7 and SNAP-47 using a proteomics approach. We found that SNAP-47 mainly localized to cytoplasm, the endoplasmic reticulum (ER), and ERGIC and could also shuttle between the cytoplasm and the nucleus. SNAP-47 preferentially interacted with the trans-Golgi network VAMP4 and post-Golgi VAMP7 and -8. SNAP-47 also interacted with ER and Golgi syntaxin 5 and with syntaxin 1 in the absence of Munc18a, when syntaxin 1 is retained in the ER. A C-terminally truncated SNAP-47 was impaired in interaction with VAMPs and affected their subcellular distribution. SNAP-47 silencing further shifted the subcellular localization of VAMP4 from the Golgi apparatus to the ER. WT and mutant SNAP-47 overexpression impaired VAMP7 exocytic activity. We conclude that SNAP-47 plays a role in the proper localization and function of a subset of VAMPs likely via regulation of their transport through the early secretory pathway.

Expression of synaptosomal-associated protein in non-small cell lung cancer / 医学研究生学报

[Abstract ] Objective Numerous studies had shown that synaptic-associated proteins (SNAPs) were closely related to the occurrence and development of tumors .The aim of this study was to investigate the expression of synaptosomal-associated protein 47 (SNAP47) and its correlation with the clinicopathological features in non-small cell lung cancer(NSCLC). Methods The expres-sions of SNAP family (SNAP23, SNAP25, SNAP29 and SNAP47) were extracted and analyzed through the gene expression microarray and the cancer genome atlas ( TCGA) data-base.SNAP47 mRNA expression in 52 cases of lung adenocarcinoma and their correspond-ing normal tissues were detected by quantitative real-time PCR ( qRT-PCR) . Results Among 52 cases of lung adenocarcinoma , SNAP47 mRNA expression levels of 41 cases(78.9%) were significantly higher than the adjacent lung tissue (P<0.05).The mRNA level of SNAP47 was associated with lymph node invasion and advanced clinical patho-logical stage .The mRNA levels of SNAP47 of patients in II/III stage were significantly higher than those of I stage patients ( 6.558 ± 4.730 vs 2.718 ±2.370, P<0.05).The mRNA levels of N1+N2 were higher than those of N0 (6.609 ±4.942 vs 3.360 ±2.987,P<0.05). Conclusion The high specificity of SNAP47 expression in lung cancer tissues might be associated with the invasion and lymph node metastasis of NSCLC , which is the potential therapeutic target of lung cancer .