PDZ domains: fundamental building blocks in the organization of protein complexes at the plasma membrane

E4orf1: The triple agent of adenovirus - Unraveling its roles in oncogenesis, infectious obesity and immune responses in virus replication and vector therapy

Human Adenoviruses (HAdV) are nearly ubiquitous pathogens comprising numerous sub-types that infect various tissues and organs. Among many encoded proteins that facilitate viral replication and subversion of host cellular processes, the viral E4orf1 protein has emerged as an intriguing yet under-investigated player in the complex interplay between the virus and its host. E4orf1 has gained attention as a metabolism activator and oncogenic agent, while recent research is showing that E4orf1 may play a more important role in modulating cellular pathways such as PI3K-Akt-mTOR, Ras, the immune response and further HAdV replication stages than previously anticipated. In this review, we aim to explore the structure, molecular mechanisms, and biological functions of E4orf1, shedding light on its potentially multifaceted roles during HAdV infection, including metabolic diseases and oncogenesis. Furthermore, we discuss the role of functional E4orf1 in biotechnological applications such as Adenovirus (AdV) vaccine vectors and oncolytic AdV. By dissecting the intricate relationships between HAdV types and E4orf1 proteins, this review provides valuable insights into viral pathogenesis and points to promising areas of future research.

Nonsynonymous Mutations in Intellectual Disability and Autism Spectrum Disorder Gene PTCHD1 Disrupt N-Glycosylation and Reduce Protein Stability

PTCHD1 has been implicated in Autism Spectrum Disorders (ASDs) and/or intellectual disability, where copy-number-variant losses or loss-of-function coding mutations segregate with disease in an X-linked recessive fashion. Missense variants of PTCHD1 have also been reported in patients. However, the significance of these mutations remains undetermined since the activities, subcellular localization, and regulation of the PTCHD1 protein are currently unknown. This paucity of data concerning PTCHD1 prevents the effective evaluation of sequence variants identified during diagnostic screening. Here, we characterize PTCHD1 protein binding partners, extending previously reported interactions with postsynaptic scaffolding protein, SAP102. Six rare missense variants of PTCHD1 were also identified from patients with neurodevelopmental disorders. After modelling these variants on a hypothetical three-dimensional structure of PTCHD1, based on the solved structure of NPC1, PTCHD1 variants harboring these mutations were assessed for protein stability, post-translational processing, and protein trafficking. We show here that the wild-type PTCHD1 post-translational modification includes complex N-glycosylation and that specific mutant proteins disrupt normal N-link glycosylation processing. However, regardless of their processing, these mutants still localized to PSD95-containing dendritic processes and remained competent for complexing SAP102.

Targeting PKC alleviates iron overload in diabetes and hemochromatosis

Diabetes is one of the most prevalent chronic diseases worldwide. Iron overload increases the incidence of diabetes and aggravates diabetic complications that cause mortality. Reciprocally, diabetes potentially promotes body iron loading, but the mechanism remains not well understood. In this study, we demonstrated systemic iron excess and the upregulation of iron exporter ferroportin (Fpn) in the enterocytes and macrophages of multiple diabetic mouse models. Increased Fpn expression and iron efflux was also seen in the enterocytes of type 2 diabetic human patients. We further showed that protein kinase C (PKC), which is activated in hyperglycemia, was responsible for the sustained membrane expression of Fpn in physiological and in diabetic settings. For the first time, we identified that PKCs were novel binding proteins and positive regulators of Fpn. Mechanistically, hyperactive PKC promoted exocytotic membrane insertion while inhibited the endocytic trafficking of Fpn in the resting state. PKC also protected Fpn from internalization and degradation by its ligand hepcidin dependent on decreased ubiquitination and increased phosphorylation of Fpn. Importantly, the loss-of-function and pharmacological inhibition of PKC alleviated systemic iron overload in diabetes and hemochromatosis. Our study thus highlights PKC as a novel target in the control of systemic iron homeostasis.

PDZ and LIM Domain-Encoding Genes: Their Role in Cancer Development

PDZ-LIM family proteins (PDLIMs) are a kind of scaffolding proteins that contain PDZ and LIM interaction domains. As protein-protein interacting molecules, PDZ and LIM domains function as scaffolds to bind to a variety of proteins. The PDLIMs are composed of evolutionarily conserved proteins found throughout different species. They can participate in cell signal transduction by mediating the interaction of signal molecules. They are involved in many important physiological processes, such as cell differentiation, proliferation, migration, and the maintenance of cellular structural integrity. Studies have shown that dysregulation of the PDLIMs leads to tumor formation and development. In this paper, we review and integrate the current knowledge on PDLIMs. The structure and function of the PDZ and LIM structural domains and the role of the PDLIMs in tumor development are described.

Blocking the functional domain of TIP1 by antibodies sensitizes cancer to radiation therapy

Non-small-cell lung cancer (NSCLC) and glioblastoma (GB) have poor prognoses. Discovery of new molecular targets is needed to improve therapy. Tax interacting protein 1 (TIP1), which plays a role in cancer progression, is overexpressed and radiation-inducible in NSCLC and GB. We evaluated the effect of an anti-TIP1 antibody alone and in combination with ionizing radiation (XRT) on NSCLC and GB in vitro and in vivo. NSCLC and GB cells were treated with anti-TIP1 antibodies and evaluated for proliferation, colony formation, endocytosis, and cell death. The efficacy of anti-TIP1 antibodies in combination with XRT on tumor growth was measured in mouse models of NSCLC and GB. mRNA sequencing was performed to understand the molecular mechanisms involved in the action of anti-TIP1 antibodies. We found that targeting the functional domain of TIP1 leads to endocytosis of the anti-TIP1 antibody followed by reduced proliferation and increased apoptosis-mediated cell death. Anti-TIP1 antibodies bound specifically (with high affinity) to cancer cells and synergized with XRT to significantly increase cytotoxicity in vitro and reduce tumor growth in mouse models of NSCLC and GB. Importantly, downregulation of cancer survival signaling pathways was found in vitro and in vivo following treatment with anti-TIP1 antibodies. TIP1 is a new therapeutic target for cancer treatment. Antibodies targeting the functional domain of TIP1 exhibited antitumor activity and enhanced the efficacy of radiation both in vitro and in vivo. Anti-TIP1 antibodies interrupt TIP1 function and are effective cancer therapy alone or in combination with XRT in mouse models of human cancer.

The impact of interaction between verteporfin and yes-associated protein 1/transcriptional coactivator with PDZ-binding motif-TEA domain pathway on the progression of isocitrate dehydrogenase wild-type glioblastoma

Verteporfin and 5-ALA are used for visualizing malignant tissue components in different body tumors and as photodynamic therapy in treating isocitrate dehydrogenase (IDH) wild-type glioblastoma (GBM). Additionally, verteporfin interferes with Yes-associated protein 1 (YAP)/Transcriptional coactivator with PDZ-binding motif - TEA domain (TAZ-TEAD) pathway, thus inhibiting the downstream effect of these oncogenes and reducing the malignant properties of GBM. Animal studies have shown verteporfin to be successful in increasing survival rates, which have led to the conduction of phase 1 and 2 clinical trials to further investigate its efficacy in treating GBM. In this article, we aimed to review the novel mechanism of verteporfin's action, the impact of its interaction with YAP/TAZ-TEAD, its effect on glioblastoma stem cells, and its role in inducing ferroptosis.

Storming the gate: New approaches for targeting the dynamic tight junction for improved drug delivery

As biologics used in the clinic outpace the number of new small molecule drugs, an important challenge for their efficacy and widespread use has emerged, namely tissue penetrance. Macromolecular drugs - bulky, high-molecular weight, hydrophilic agents - exhibit low permeability across biological barriers. Epithelial and endothelial layers, for example within the gastrointestinal tract or at the blood-brain barrier, present the most significant obstacle to drug transport. Within epithelium, two subcellular structures are responsible for limiting absorption: cell membranes and intercellular tight junctions. Previously considered impenetrable to macromolecular drugs, tight junctions control paracellular flux and dictate drug transport between cells. Recent work, however, has shown tight junctions to be dynamic, anisotropic structures that can be targeted for delivery. This review aims to summarize new approaches for targeting tight junctions, both directly and indirectly, and to highlight how manipulation of tight junction interactions may help usher in a new era of precision drug delivery.

The Architecture of the Presynaptic Release Site

The architecture of the presynaptic release site is exquisitely designed to facilitate and regulate synaptic vesicle exocytosis. With the identification of some of the building blocks of the active zone and the advent of super resolution imaging techniques, we are beginning to understand the morphological and functional properties of synapses in great detail. Presynaptic release sites consist of the plasma membrane, the cytomatrix, and dense projections. These three components are morphologically distinct but intimately connected with each other and with postsynaptic specializations, ensuring the fidelity of synaptic vesicle tethering, docking, and fusion, as well as signal detection. Although the morphology and molecular compositions of active zones may vary among species, tissues, and cells, global architectural design of the release sites is highly conserved.

Novel organic selenium source hydroxy-selenomethionine counteracts the blood-milk barrier disruption and inflammatory response of mice under heat stress

Heat stress (HS) in summer has caused huge economic losses to animal husbandry production recently. When mammary gland is exposed to high temperatures, it will cause blood-milk barrier damage. Hydroxy-selenomethionine (HMSeBA) is a new selenium source with better guarantee of animals' production performance under stress, but whether it has protective effect on heat stress-induced blood-milk damage is still unclear. We established mammary epithelial cells and mice heat stress injury models to fill this research gap, and hope to provide theoretical basis for using HMSeBA to alleviate heat stress damage mammary gland. The results showed that (1) Heat stress significantly decreases in vitro transepithelial electrical resistance (TEER) and cell viability (P < 0.01), and significantly decreases clinical score, histological score, and total alveoli area of mice mammary gland tissue (P < 0.01). (2) HMSeBA significantly increases TEER and fluorescein sodium leakage of HS-induced monolayer BMECs (P < 0.01), significantly improves the milk production and total area of alveoli (P < 0.01), and reduces clinical score, histological score, mRNA expression of heat stress-related proteins, and inflammatory cytokines release of heat-stressed mice (P < 0.01). (3) HMSeBA significantly improves tight junction structure damage, and significantly up-regulated the expression of tight junction proteins (ZO-1, claudin 1, and occludin) as well as signal molecules PI3K, AKT, and mTOR (P < 0.01) in heat-stressed mammary tissue. (4) HMSeBA significantly increases glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and superoxide dismutase release (SOD) (P < 0.01) and significantly reduce malondialdehyde (MDA) expression (P < 0.01) in heat-stressed mammary tissue. In conclusion, this study implemented heat-stressed cell and mice model and showed that HMSeBA significantly regulate antioxidant capacity, inhibited inflammation, and regulate tight junction proteins expression in blood-milk barrier via PI3K/AKT/mTOR signaling pathway, so as to alleviate mammary gland damage and ensure its structure and function integrity.

Nuclear entry and egress of parvoviruses

Parvoviruses are small non-enveloped single-stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure of nuclear localization sequence and a phospholipase A₂ domain on the capsid surface, and escape into the cytosol, parvovirus capsids enter the nucleus. Due to the small capsid diameter of 18-26 nm, intact capsids can potentially pass into the nucleus through nuclear pore complexes (NPCs). This might be facilitated by active nuclear import, but capsids may also follow an alternative entry pathway that includes activation of mitotic factors and local transient disruption of the nuclear envelope. The nuclear entry is followed by currently undefined events of viral genome uncoating. After genome release, viral replication compartments are initiated and infection proceeds. Parvoviral genomes replicate during cellular S phase followed by nuclear capsid assembly during virus-induced S/G2 cell cycle arrest. Nuclear egress of capsids occurs upon nuclear envelope degradation during apoptosis and cell lysis. An alternative pathway for nuclear export has been described using active transport through the NPC mediated by the chromosome region maintenance 1 protein, CRM1, which is enhanced by phosphorylation of the N-terminal domain of VP2. However, other alternative but not yet uncharacterized nuclear export pathways cannot be excluded.

Isoflurane Disrupts Postsynaptic Density-95 Protein Interactions Causing Neuronal Synapse Loss and Cognitive Impairment in Juvenile Mice via Canonical NO-mediated Protein Kinase-G Signaling

BACKGROUND

Inhalational anesthetics are known to disrupt PDZ2 domain-mediated protein-protein interactions of the postsynaptic density (PSD)-95 protein. The aim of this study is to investigate the underlying mechanisms in response to early isoflurane exposure on synaptic PSD-95 PDZ2 domain disruption that altered spine densities and cognitive function. The authors hypothesized that activation of protein kinase-G by the components of nitric oxide (NO) signaling pathway constitutes a mechanism that prevents loss of early dendritic spines and synapse in neurons and cognitive impairment in mice in response to disruption of PDZ2 domain of the PSD-95 protein.

METHODS

Postnatal day 7 mice were exposed to 1.5% isoflurane for 4 h or injected with 8 mg/kg active PSD-95 wild-type PDZ2 peptide or soluble guanylyl cyclase activator YC-1 along with their respective controls. Primary neurons at 7 days in vitro were exposed to isoflurane or PSD-95 wild-type PDZ2 peptide for 4 h. Coimmunoprecipitation, spine density, synapses, cyclic guanosine monophosphate-dependent protein kinase activity, and novel object recognition memory were assessed.

RESULTS

Exposure of isoflurane or PSD-95 wild-type PDZ2 peptide relative to controls causes the following. First, there is a decrease in PSD-95 coimmunoprecipitate relative to N-methyl-d-aspartate receptor subunits NR2A and NR2B precipitate (mean ± SD [in percentage of control]: isoflurane, 54.73 ± 16.52, P = 0.001; and PSD-95 wild-type PDZ2 peptide, 51.32 ± 12.93, P = 0.001). Second, there is a loss in spine density (mean ± SD [spine density per 10 µm]: control, 5.28 ± 0.56 vs. isoflurane, 2.23 ± 0.67, P < 0.0001; and PSD-95 mutant PDZ2 peptide, 4.74 ± 0.94 vs. PSD-95 wild-type PDZ2 peptide, 1.47 ± 0.87, P < 0.001) and a decrease in synaptic puncta (mean ± SD [in percentage of control]: isoflurane, 41.1 ± 14.38, P = 0.001; and PSD-95 wild-type PDZ2 peptide, 50.49 ± 14.31, P < 0.001). NO donor or cyclic guanosine monophosphate analog prevents the spines and synapse loss and decline in the cyclic guanosine monophosphate-dependent protein kinase activity, but this prevention was blocked by soluble guanylyl cyclase or protein kinase-G inhibitors in primary neurons. Third, there were deficits in object recognition at 5 weeks (mean ± SD [recognition index]: male, control, 64.08 ± 10.57 vs. isoflurane, 48.49 ± 13.41, P = 0.001, n = 60; and female, control, 67.13 ± 11.17 vs. isoflurane, 53.76 ± 6.64, P = 0.003, n = 58). Isoflurane-induced impairment in recognition memory was preventable by the introduction of YC-1.

CONCLUSIONS

Activation of soluble guanylyl cyclase or protein kinase-G prevents isoflurane or PSD-95 wild-type PDZ2 peptide-induced loss of dendritic spines and synapse. Prevention of recognition memory with YC-1, a NO-independent activator of guanylyl cyclase, supports a role for the soluble guanylyl cyclase mediated protein kinase-G signaling in countering the effects of isoflurane-induced cognitive impairment.

EDITOR’S PERSPECTIVE

Junctional Adhesion Molecules: Potential Proteins in Atherosclerosis

Junctional adhesion molecules (JAMs) are cell-cell adhesion molecules of the immunoglobulin superfamily and are involved in the regulation of diverse atherosclerosis-related processes such as endothelial barrier maintenance, leucocytes transendothelial migration, and angiogenesis. To combine and further broaden related results, this review concluded the recent progress in the roles of JAMs and predicted future studies of JAMs in the development of atherosclerosis.

The PLEKHA7-PDZD11 complex regulates the localization of the calcium pump PMCA and calcium handling in cultured cells

The plasma membrane calcium ATPase (PMCA) extrudes calcium from the cytosol to the extracellular space to terminate calcium-dependent signaling. Although the distribution of PMCA is crucial for its function, the molecular mechanisms that regulate the localization of PMCA isoforms are not well understood. PLEKHA7 is implicated by genetic studies in hypertension and the regulation of calcium handling. PLEKHA7 recruits the small adapter protein PDZD11 to adherens junctions, and together they control the trafficking and localization of plasma membrane associated proteins, including the Menkes copper ATPase. Since PDZD11 binds to the C-terminal domain of b-isoforms of PMCA, PDZD11 and its interactor PLEKHA7 could control the localization and activity of PMCA. Here, we test this hypothesis using cultured cell model systems. We show using immunofluorescence microscopy and a surface biotinylation assay that KO of either PLEKHA7 or PDZD11 in mouse kidney collecting duct epithelial cells results in increased accumulation of endogenous PMCA at lateral cell–cell contacts and PDZ-dependent ectopic apical localization of exogenous PMCA4x/b isoform. In HeLa cells, coexpression of PDZD11 reduces membrane accumulation of overexpressed PMCA4x/b, and analysis of cytosolic calcium transients shows that PDZD11 counteracts calcium extrusion activity of overexpressed PMCA4x/b, but not PMCA4x/a, which lacks the PDZ-binding motif. Moreover, KO of PDZD11 in either endothelial (bEnd.3) or epithelial (mouse kidney collecting duct) cells increases the rate of calcium extrusion. Collectively, these results suggest that the PLEKHA7–PDZD11 complex modulates calcium homeostasis by regulating the localization of PMCA.

Tight junctions: from molecules to gastrointestinal diseases

Intestinal epithelium functions as a tissue barrier to prevent interaction between the internal compartment and the external milieu. Intestinal barrier function also determines epithelial polarity for the absorption of nutrients and the secretion of waste products. These vital functions require strong integrity of tight junction proteins. In fact, intestinal tight junctions that seal the paracellular space can restrict mucosal-to-serosal transport of hostile luminal contents. Tight junctions can form both an absolute barrier and a paracellular ion channel. Although defective tight junctions potentially lead to compromised intestinal barrier and the development and progression of gastrointestinal (GI) diseases, no FDA-approved therapies that recover the epithelial tight junction barrier are currently available in clinical practice. Here, we discuss the impacts and regulatory mechanisms of tight junction disruption in the gut and related diseases. We also provide an overview of potential therapeutic targets to restore the epithelial tight junction barrier in the GI tract.

The ACE2 Receptor for Coronavirus Entry Is Localized at Apical Cell—Cell Junctions of Epithelial Cells

Transmembrane proteins of adherens and tight junctions are known targets for viruses and bacterial toxins. The coronavirus receptor ACE2 has been localized at the apical surface of epithelial cells, but it is not clear whether ACE2 is localized at apical Cell—Cell junctions and whether it associates with junctional proteins. Here we explored the expression and localization of ACE2 and its association with transmembrane and tight junction proteins in epithelial tissues and cultured cells by data mining, immunoblotting, immunofluorescence microscopy, and co-immunoprecipitation experiments. ACE2 mRNA is abundant in epithelial tissues, where its expression correlates with the expression of the tight junction proteins cingulin and occludin. In cultured epithelial cells ACE2 mRNA is upregulated upon differentiation and ACE2 protein is widely expressed and co-immunoprecipitates with the transmembrane proteins ADAM17 and CD9. We show by immunofluorescence microscopy that ACE2 colocalizes with ADAM17 and CD9 and the tight junction protein cingulin at apical junctions of intestinal (Caco-2), mammary (Eph4) and kidney (mCCD) epithelial cells. These observations identify ACE2, ADAM17 and CD9 as new epithelial junctional transmembrane proteins and suggest that the cytokine-enhanced endocytic internalization of junction-associated protein complexes comprising ACE2 may promote coronavirus entry.

Effects of Selenium as a Dietary Source on Performance, Inflammation, Cell Damage, and Reproduction of Livestock Induced by Heat Stress: A Review

Heat stress as a result of global warming has harmful consequences for livestock and is thus becoming an urgent issue for animal husbandry worldwide. Ruminants, growing pigs, and poultry are very susceptible to heat stress because of their fast growth, rapid metabolism, high production levels, and sensitivity to temperature. Heat stress compromises the efficiency of animal husbandry by affecting performance, gastrointestinal health, reproductive physiology, and causing cell damage. Selenium (Se) is an essential nutritional trace element for livestock production, which acts as a structural component in at least 25 selenoproteins (SELs); it is involved in thyroid hormone synthesis, and plays a key role in the antioxidant defense system. Dietary Se supplementation has been confirmed to support gastrointestinal health, production performance, and reproductive physiology under conditions of heat stress. The underlying mechanisms include the regulation of nutrient digestibility influenced by gastrointestinal microorganisms, antioxidant status, and immunocompetence. Moreover, heat stress damage to the gastrointestinal and mammary barrier is closely related to cell physiological functions, such as the fluidity and stability of cellular membranes, and the inhibition of receptors as well as transmembrane transport protein function. Se also plays an important role in inhibiting cell apoptosis and reducing cell inflammatory response induced by heat stress. This review highlights the progress of research regarding the dietary supplementation of Se in the mitigation of heat stress, addressing its mechanism and explaining the effect of Se on cell damage caused by heat stress, in order to provide a theoretical reference for the use of Se to mitigate heat stress in livestock.

A novel effect of PDLIM5 in α7 nicotinic acetylcholine receptor upregulation and surface expression

Nicotinic acetylcholine receptors (nAChRs) are widespread throughout the central nervous system. Signaling through nAChRs contributes to numerous higher-order functions, including memory and cognition, as well as abnormalities such as nicotine addiction and neurodegenerative disorders. Although recent studies indicate that the PDZ-containing proteins comprising PSD-95 family co-localize with nicotinic acetylcholine receptors and mediate downstream signaling in the neurons, the mechanisms by which α7nAChRs are regulated remain unclear. Here, we show that the PDZ-LIM domain family protein PDLIM5 binds to α7nAChRs and plays a role in nicotine-induced α7nAChRs upregulation and surface expression. We find that chronic exposure to 1 μM nicotine upregulated α7, β2-contained nAChRs and PDLIM5 in cultured hippocampal neurons, and the upregulation of α7nAChRs and PDLIM5 is increased more on the cell membrane than the cytoplasm. Interestingly, in primary hippocampal neurons, α7nAChRs and β2nAChRs display distinct patterns of expression, with α7nAChRs colocalized more with PDLIM5. Furthermore, PDLIM5 interacts with α7nAChRs, but not β2nAChRs in native brain neurons. Knocking down of PDLIM5 in SH-SY5Y abolishes nicotine-induced upregulation of α7nAChRs. In primary hippocampal neurons, using shRNA against PDLIM5 decreased both surface clustering of α7nAChRs and α7nAChRs-mediated currents. Proteomics analysis and isothermal titration calorimetry (ITC) results show that PDLIM5 interacts with α7nAChRs through the PDZ domain, and the interaction between PDLIM5 and α7nAChRs can be promoted by nicotine. Collectively, our data suggest a novel cellular role of PDLIM5 in the regulation of α7nAChRs, which may be relevant to plastic changes in the nervous system.

Dehydration-responsive chickpea chloroplast protein, CaPDZ1, confers dehydration tolerance by improving photosynthesis

The screening of a dehydration-responsive chloroplast proteome of chickpea led us to identify and investigate the functional importance of an uncharacterized protein, designated CaPDZ1. In all, we identified 14 CaPDZs, and phylogenetic analysis revealed that these belong to photosynthetic eukaryotes. Sequence analyses of CaPDZs indicated that CaPDZ1 is a unique member, which harbours a TPR domain besides a PDZ domain. The global expression analysis showed that CaPDZs are intimately associated with various stresses such as dehydration and oxidative stress along with certain phytohormone responses. The CaPDZ1-overexpressing chickpea seedlings exhibited distinct phenotypic and molecular responses, particularly increased photosystem (PS) efficiency, ETR and qP that validated its participation in PSII complex assembly and/or repair. The investigation of CaPDZ1 interacting proteins through Y2H library screening and co-IP analysis revealed the interacting partners to be PSII associated CP43, CP47, D1, D2 and STN8. These findings supported the earlier hypothesis regarding the role of direct or indirect involvement of PDZ proteins in PS assembly or repair. Moreover, the GUS-promoter analysis demonstrated the preferential expression of CaPDZ1 specifically in photosynthetic tissues. We classified CaPDZ1 as a dehydration-responsive chloroplast intrinsic protein with multi-fold abundance under dehydration stress, which may participate synergistically with other chloroplast proteins in the maintenance of the photosystem.

Induction and Evasion of Type-I Interferon Responses during Influenza A Virus Infection

Influenza A viruses (IAVs) are contagious pathogens and one of the leading causes of respiratory tract infections in both humans and animals worldwide. Upon infection, the innate immune system provides the first line of defense to neutralize or limit the replication of invading pathogens, creating a fast and broad response that brings the cells into an alerted state through the secretion of cytokines and the induction of the interferon (IFN) pathway. At the same time, IAVs have developed a plethora of immune evasion mechanisms in order to avoid or circumvent the host antiviral response, promoting viral replication. Herein, we will review and summarize already known and recently described innate immune mechanisms that host cells use to fight IAV viral infections as well as the main strategies developed by IAVs to overcome such powerful defenses during this fascinating virus-host interplay.

PDLIM2: Signaling pathways and functions in cancer suppression and host immunity

PDZ and LIM domains-containing proteins play pivotal functions in cell cytoskeleton organization, cell polarization and differentiation. As a key member of the family, PDLIM2 regulates stability and activity of transcription factors such as NF-κB, STATs and β-catenin, and thus exert it functions in inflammation, immunity, and cancer. PDLIM2 functions as a tumor suppressor in multiple tissues and it is often genetically mutated or epigenetically silenced in human cancers derived from lung, breast, ovarian and other histologies. However, in certain types of cancers, PDLIM2 may promote cancer cell proliferation and metastases. Therefore, PDLIM2 is added to a long list of genes that can function as tumor suppressor or oncogenic protein. During tumorigenesis induced by oncogenic viruses, PDLIM2 is a key target. Through promotion of NF-κB/RelA and STAT3 degradation, PDLIM2 enhances expression of proteins involved in antigen presentation and promotes T-cell activation while repressing multidrug resistance genes, thereby rendering mutated cells susceptible to immune surveillance and cytotoxicity mediated by immune cells and chemotherapeutic drugs. Intriguingly, PDLIM2 in alveolar macrophages (AMs) plays key roles in monitoring lung tumorigenesis, as its selective genetic deletion leads to constitutive activation of STAT3, driving monocyte differentiation to AMs with pro-tumorigenic polarization and activation. PDLIM2 has also been explored as a therapeutic target for cancer therapy. At the end of this review, we provide perspectives on this important molecule and discuss the future directions of both basic and translational studies.

JAK-STAT Pathway Regulation of Intestinal Permeability: Pathogenic Roles and Therapeutic Opportunities in Inflammatory Bowel Disease

The epithelial barrier forms the interface between luminal microbes and the host immune system and is the first site of exposure to many of the environmental factors that trigger disease activity in chronic inflammatory bowel disease (IBD). Disruption of the epithelial barrier, in the form of increased intestinal permeability, is a feature of IBD and other inflammatory diseases, including celiac disease and type 1 diabetes. Variants in genes that regulate or belong to the JAK-STAT signaling pathway are associated with IBD risk. Inhibitors of the JAK-STAT pathway are now effective therapeutic options in IBD. This review will discuss emerging evidence that JAK inhibitors can be used to improve defects in intestinal permeability and how this plays a key role in resolving intestinal inflammation.

Physiological and Pathological Functions of SLC26A6

Solute Carrier Family 26 (SLC26) is a conserved anion transporter family with 10 members in human (SLC26A1-A11, A10 being a pseudogene). All SLC26 genes except for SLC26A5 (prestin) are versatile anion exchangers with notable ability to transport a variety of anions. SLC26A6 has the most extensive exchange functions in the SLC26 family and is widely expressed in various organs and tissues of mammals. SLC26A6 has some special properties that make it play a particularly important role in ion homeostasis and acid-base balance. In the past few years, the function of SLC26A6 in the diseases has received increasing attention. SLC26A6 not only participates in the development of intestinal and pancreatic diseases but also serves a significant role in mediating nephrolithiasis, fetal skeletal dysplasia and arrhythmia. This review aims to explore the role of SLC26A6 in physiology and pathophysiology of relative mammalian organs to guide in-depth studies about related diseases of human.

A long isoform of GIV/Girdin contains a PDZ-binding module that regulates localization and G-protein binding

PDZ domains are one of the most abundant protein domains in eukaryotes and are frequently found on junction-localized scaffold proteins. Various signaling molecules bind to PDZ proteins via PDZ-binding motifs (PBM) and fine-tune cellular signaling. However, how such interaction affects protein function is difficult to predict and must be solved empirically. Here we describe a long isoform of the guanine nucleotide exchange factor GIV/Girdin (CCDC88A) that we named GIV-L, which is conserved throughout evolution, from invertebrates to vertebrates, and contains a PBM. Unlike GIV, which lacks PBM and is cytosolic, GIV-L localizes onto cell junctions and has a PDZ interactome (as shown through annotating Human Cell Map and BioID-proximity labeling studies), which impacts GIV-L's ability to bind and activate trimeric G-protein, Gαi, through its guanine-nucleotide exchange modulator (GEM) module. This GEM module is found exclusively in vertebrates. We propose that the two functional modules in GIV may have evolved sequentially: the ability to bind PDZ proteins via the PBM evolved earlier in invertebrates, whereas G-protein binding and activation may have evolved later only among vertebrates. Phenotypic studies in Caco-2 cells revealed that GIV and GIV-L may have antagonistic effects on cell growth, proliferation (cell cycle), and survival. Immunohistochemical analysis in human colon tissues showed that GIV expression increases with a concomitant decrease in GIV-L during cancer initiation. Taken together, these findings reveal how regulation in GIV/CCDC88A transcript helps to achieve protein modularity, which allows the protein to play opposing roles either as a tumor suppressor (GIV-L) or as an oncogene (GIV).

Dual Role of the PTPN13 Tyrosine Phosphatase in Cancer

In this review article, we present the current knowledge on PTPN13, a class I non-receptor protein tyrosine phosphatase identified in 1994. We focus particularly on its role in cancer, where PTPN13 acts as an oncogenic protein and also a tumor suppressor. To try to understand these apparent contradictory functions, we discuss PTPN13 implication in the FAS and oncogenic tyrosine kinase signaling pathways and in the associated biological activities, as well as its post-transcriptional and epigenetic regulation. Then, we describe PTPN13 clinical significance as a prognostic marker in different cancer types and its impact on anti-cancer treatment sensitivity. Finally, we present future research axes following recent findings on its role in cell junction regulation that implicate PTPN13 in cell death and cell migration, two major hallmarks of tumor formation and progression.

Usher Syndrome: Genetics and Molecular Links of Hearing Loss and Directions for Therapy

Usher syndrome (USH) is an autosomal recessive (AR) disorder that permanently and severely affects the senses of hearing, vision, and balance. Three clinically distinct types of USH have been identified, decreasing in severity from Type 1 to 3, with symptoms of sensorineural hearing loss (SNHL), retinitis pigmentosa (RP), and vestibular dysfunction. There are currently nine confirmed and two suspected USH-causative genes, and a further three candidate loci have been mapped. The proteins encoded by these genes form complexes that play critical roles in the development and maintenance of cellular structures within the inner ear and retina, which have minimal capacity for repair or regeneration. In the cochlea, stereocilia are located on the apical surface of inner ear hair cells (HC) and are responsible for transducing mechanical stimuli from sound pressure waves into chemical signals. These signals are then detected by the auditory nerve fibers, transmitted to the brain and interpreted as sound. Disease-causing mutations in USH genes can destabilize the tip links that bind the stereocilia to each other, and cause defects in protein trafficking and stereocilia bundle morphology, thereby inhibiting mechanosensory transduction. This review summarizes the current knowledge on Usher syndrome with a particular emphasis on mutations in USH genes, USH protein structures, and functional analyses in animal models. Currently, there is no cure for USH. However, the genetic therapies that are rapidly developing will benefit from this compilation of detailed genetic information to identify the most effective strategies for restoring functional USH proteins.

Approaches to Investigating the Protein Interactome of PTEN

The tumor suppressor phosphatase and tensin homologue (PTEN) is a redox-sensitive dual specificity phosphatase with an essential role in the negative regulation of the PI3K-AKT signaling pathway, affecting metabolic and cell survival processes. PTEN is commonly mutated in cancer, and dysregulation in the metabolism of PIP₃ is implicated in other diseases such as diabetes. PTEN interactors are responsible for some functional roles of PTEN beyond the negative regulation of the PI3K pathway and are thus of great importance in cell biology. Both high-data content proteomics-based approaches and low-data content PPI approaches have been used to investigate the interactome of PTEN and elucidate further functions of PTEN. While low-data content approaches rely on co-immunoprecipitation and Western blotting, and as such require previously generated hypotheses, high-data content approaches such as affinity pull-down proteomic assays or the yeast 2-hybrid system are hypothesis generating. This review provides an overview of the PTEN interactome, including redox effects, and critically appraises the methods and results of high-data content investigations into the global interactome of PTEN. The biological significance of findings from recent studies is discussed and illustrates the breadth of cellular functions of PTEN that can be discovered by these approaches.

Evolution of Modularity, Interactome and Functions of GIV/Girdin (CCDC88A) from Invertebrates to Vertebrates.. [DOI: 10.1101/2020.09.28.317172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

PDZ domains are one of the most abundant protein domains in eukaryotes and frequently found on junction-localized scaffold proteins. Various signaling molecules bind to PDZ proteins via PDZ-binding motifs (PBM) and finetune cellular signaling. Here we describe the presence of a PBM on GIV/Girdin (CCDC88A) that is conserved throughout evolution, from invertebrates to vertebrates, and is generated as a long isoform-variant in humans, which we named GIV-L. Unlike GIV, which lacks PBM and is cytosolic, GIV-L localizes to the cell junctions, and has a unique PDZ-interactome, which impacts GIV-L’s ability to bind and activate trimeric G-protein, Gi through its guanine-nucleotide exchange modulator (GEM) module; the GEM module is found exclusively in vertebrates. Thus, the two functional modules in GIV evolved sequentially: the ability to bind PDZ proteins via the PBM evolved earlier in invertebrates, whereas G-protein binding and activation may have evolved later only among vertebrates. Phenotypic studies in Caco-2 cells revealed that GIV and GIV-L may have antagonistic effects on cell growth, proliferation (cell cycle), and survival. Immunohistochemical analyses in human colon tissues showed that GIV expression increases with a concomitant decrease in GIV-L during cancer initiation. Taken together, these findings reveal how GIV/CCDC88A in humans displays evolutionary flexibility in modularity, which allows the resultant isoforms to play opposing roles either as a tumor suppressor (GIV-L) or as an oncogene (GIV).

An Overview of the Cytoskeleton-Associated Role of PDLIM5

Regenerative medicine represented by stem cell technology has become one of the pillar medical technologies for human disease treatment. Cytoskeleton plays important roles in maintaining cell morphology, bearing external forces, and maintaining the effectiveness of cell internal structure, among which cytoskeleton related proteins are involved in and play an indispensable role in the changes of cytoskeleton. PDLIM5 is a cytoskeleton-related protein that, like other cytoskeletal proteins, acts as a binding protein. PDZ and LIM domain 5 (PDLIM5), also known as ENH (Enigma homolog), is a cytoplasmic protein with a molecular mass of about 63 KDa that consists of a PDZ domain at the N-terminus and three LIM domains at the C-terminus. PDLIM5 binds to the cytoskeleton and membrane proteins through its PDZ domain and interacts with various signaling molecules, including protein kinases and transcription factors, through its LIM domain. As a cytoskeleton-related protein, PDLIM5 plays an important role in regulating cell proliferation, differentiation and cell fate decision in multiple tissues and cell types. In this review, we briefly summarize the state of knowledge on the PDLIM5 gene, structural properties, and molecular functional mechanisms of the PDLIM5 protein, and its role in cells, tissues, and organ systems, and describe the possible underlying molecular signaling pathways. In the last part of this review, we will focus on discussing the limitations of existing research and the future prospects of PDLIM5 research in turn.

A Preliminary Study of the Virome of the South American Free-Tailed Bats (Tadarida brasiliensis) and Identification of Two Novel Mammalian Viruses

Bats provide important ecosystem services as pollinators, seed dispersers, and/or insect controllers, but they have also been found harboring different viruses with zoonotic potential. Virome studies in bats distributed in Asia, Africa, Europe, and North America have increased dramatically over the past decade, whereas information on viruses infecting South American species is scarce. We explored the virome of Tadarida brasiliensis, an insectivorous New World bat species inhabiting a maternity colony in Rosario (Argentina), by a metagenomic approach. The analysis of five pooled oral/anal swab samples indicated the presence of 43 different taxonomic viral families infecting a wide range of hosts. By conventional nucleic acid detection techniques and/or bioinformatics approaches, the genomes of two novel viruses were completely covered clustering into the Papillomaviridae (Tadarida brasiliensis papillomavirus type 1, TbraPV1) and Genomoviridae (Tadarida brasiliensis gemykibivirus 1, TbGkyV1) families. TbraPV1 is the first papillomavirus type identified in this host and the prototype of a novel genus. TbGkyV1 is the first genomovirus reported in New World bats and constitutes a new species within the genus Gemykibivirus. Our findings extend the knowledge about oral/anal viromes of a South American bat species and contribute to understand the evolution and genetic diversity of the novel characterized viruses.

Impact of high dietary plant protein with or without marine ingredients in gut mucosa proteome of gilthead seabream (Sparus aurata, L.)

The digestive tract, particularly the intestine, represents one of the main sites of interactions with the environment, playing the gut mucosa a crucial role in the digestion and absorption of nutrients, and in the immune defence. Previous researches have proven that the fishmeal replacement by plant sources could have an impact on the intestinal status at both digestive and immune level, compromising relevant productive parameters, such as feed efficiency, growth or survival. In order to evaluate the long-term impact of total fishmeal replacement on intestinal mucosa, the gut mucosa proteome was analysed in fish fed with a fishmeal-based diet, against plant protein-based diets with or without alternative marine sources inclusion. Total fishmeal replacement without marine ingredients inclusion, reported a negative impact in growth and biometric parameters, further an altered gut mucosa proteome. However, the inclusion of a low percentage of marine ingredients in plant protein-based diets was able to maintain the growth, biometrics parameters and gut mucosa proteome with similar values to FM group. A total fishmeal replacement induced a big set of underrepresented proteins in relation to several biological processes such as intracellular transport, assembly of cellular macrocomplex, protein localization and protein catabolism, as well as several molecular functions, mainly related with binding to different molecules and the maintenance of the cytoskeleton structure. The set of downregulated proteins also included molecules which have a crucial role in the maintenance of the normal function of the enterocytes, and therefore, of the epithelium, including permeability, immune and inflammatory response regulation and nutritional absorption. Possibly, the amino acid imbalance presented in VM diet, in a long-term feeding, may be the main reason of these alterations, which can be prevented by the inclusion of 15% of alternative marine sources. SIGNIFICANCE: Long-term feeding with plant protein based diets may be considered as a stress factor and lead to a negative impact on digestive and immune system mechanisms at the gut, that can become apparent in a reduced fish performance. The need for fishmeal replacement by alternative ingredients such as plant sources to ensure the sustainability of the aquaculture sector has led the research assessing the intestinal status of fish to be of increasing importance. This scientific work provides further knowledge about the proteins and biologic processes altered in the gut in response to plant protein based diets, suggesting the loss of part of gut mucosa functionality. Nevertheless, the inclusion of alternative marine ingredients was able to reverse these negative effects, showing as a feasible option to develop sustainable aquafeeds.

The gene structure and hypervariability of the complete Penaeus monodon Dscam gene

Using two advanced sequencing approaches, Illumina and PacBio, we derive the entire Dscam gene from an M2 assembly of the complete Penaeus monodon genome. The P. monodon Dscam (PmDscam) gene is ~266 kbp, with a total of 44 exons, 5 of which are subject to alternative splicing. PmDscam has a conserved architectural structure consisting of an extracellular region with hypervariable Ig domains, a transmembrane domain, and a cytoplasmic tail. We show that, contrary to a previous report, there are in fact 26, 81 and 26 alternative exons in N-terminal Ig2, N-terminal Ig3 and the entirety of Ig7, respectively. We also identified two alternatively spliced exons in the cytoplasmic tail, with transmembrane domains in exon variants 32.1 and 32.2, and stop codons in exon variants 44.1 and 44.2. This means that alternative splicing is involved in the selection of the stop codon. There are also 7 non-constitutive cytoplasmic tail exons that can either be included or skipped. Alternative splicing and the non-constitutive exons together produce more than 21 million isoform combinations from one PmDscam locus in the P. monodon gene. A public-facing database that allows BLAST searches of all 175 exons in the PmDscam gene has been established at http://pmdscam.dbbs.ncku.edu.tw/.

CNTNAP4 Impacts Epilepsy Through GABAA Receptors Regulation: Evidence From Temporal Lobe Epilepsy Patients and Mouse Models

Epilepsy is a serious neurological condition characterized by recurrent unprovoked seizures. The exact etiology of epilepsy is not fully understood. Here, we demonstrated that the expression of contactin-associated protein-like 4 (CNTNAP4) was decreased in the temporal neocortex of epileptic patients and in the hippocampus and cortex of epileptic mice. Lentivirus-mediated knock-down of CNTNAP4 in the hippocampus increased mice susceptibility to epilepsy. Conversely, lentivirus-mediated overexpression of CNTNAP4 decreased epileptic behavior in mice. CNTNAP4 affected neuronal excitability and inhibitory synaptic transmission via postsynaptic receptors in Mg2+-free epilepsy cell model. Down-regulation or overexpression of CNTNAP4 in the hippocampus influenced the expression of gamma-aminobutyric acid A receptor β2/3 (GABAARβ2/3) membrane protein, without affecting total GABAARβ2/3 protein concentration in epileptic mice. Protein interactions between CNTNAP4, GABAARβ2/3 and gamma-aminobutyric acid receptor-associated protein (GABARAP) were observed in the hippocampus of epileptic mice. These findings suggest CNTNAP4 may be involved in the occurrence and development of epilepsy through the regulation of GABAAR function, and may be a promising target for the development of epilepsy treatment.

Ligand-dependent intra- and interdomain motions in the PDZ12 tandem regulate binding interfaces in postsynaptic density protein-95

The postsynaptic density protein-95 (PSD-95) regulates synaptic plasticity through interactions mediated by its peptide-binding PDZ domains. The two N-terminal PDZ domains of PSD-95 form an autonomous structural unit, and their interdomain orientation and dynamics depend on ligand binding. To understand the mechanistic details of the effect of ligand binding, we generated conformational ensembles using available experimentally determined nuclear Overhauser effect interatomic distances and S² order parameters. In our approach, the fast dynamics of the two domains is treated independently. We find that intradomain structural changes induced by ligand binding modulate the probability of the occurrence of specific domain-domain orientations. Our results suggest that the β2-β3 loop in the PDZ domains is a key regulatory region, which influences both intradomain motions and supramodular rearrangement.

The protective effect of selenium from heat stress-induced porcine small intestinal epithelial cell line (IPEC-J2) injury is associated with regulation expression of selenoproteins

The present study compared the protective effect of sodium selenite (SS) and selenomethionine (SeMet) on heat stress (HS)-invoked porcine IPEC-J2 cellular damage and integrate potential roles of corresponding selenoprotein. Cells were cultured at 37°C until 80 % confluence and then subjected to four different conditions for 24 h: at 37°C (control), 41·5°C (HS), 41·5°C supplied with 0·42 µmol Se/L SS (SS), or SeMet (SeMet). HS significantly decreased cell viability, up-regulated mRNA and protein levels of heat shock protein 70 (HSP70) and down-regulated mRNA and protein levels of tight junction-related proteins (claudin-1 (CLDN-1) and zonula occludens-1 (ZO-1)). HS-induced cell injury was associated with the up-regulation (P < 0·05) of six inflammation-related genes and fourteen selenoprotein encoding genes and down-regulation (P < 0·05) of two inflammation-related genes and five selenoprotein encoding genes. Compared with the HS group, SS and SeMet supplementation resulted in an increase (P < 0·05) in cell viability, decreased (P < 0·05) mRNA expression of HSP70 and six inflammation-related genes and rescue (P < 0·05) of mRNA and protein levels of CLDN-1 and ZO-1. SS and SeMet supplementation changes the expressions of nineteen selenoprotein encoding genes in cells affected by HS. Both Se supplementation significantly recovered the protein level of glutathione peroxidase-1 and increased selenoprotein P in the IPEC-J2 cells under HS, respectively. In summary, Se supplementation alleviated the negative impact of HS on IPEC-J2 cells, and their cellular protective effect was associated with regulation expression of selenoproteins, and SeMet exhibited a better protective effect.

Perspectives of small molecule inhibitors of activin receptor‑like kinase in anti‑tumor treatment and stem cell differentiation (Review)

Activin receptor‑like kinases (ALKs), members of the type I activin receptor family, belong to the serine/threonine kinase receptors of the transforming growth factor‑β (TGF‑β) superfamily. ALKs mediate the roles of activin/TGF‑β in a wide variety of physiological and pathological processes, ranging from cell differentiation and proliferation to apoptosis. For example, the activities of ALKs are associated with an advanced tumor stage in prostate cancer and the chondrogenic differentiation of mesenchymal stem cells. Therefore, potent and selective small molecule inhibitors of ALKs would not only aid in investigating the function of activin/TGF‑β, but also in developing treatments for these diseases via the disruption of activin/TGF‑β. In recent studies, several ALK inhibitors, including LY‑2157299, SB‑431542 and A‑83‑01, have been identified and have been confirmed to affect stem cell differentiation and tumor progression in animal models. This review discusses the therapeutic perspective of small molecule inhibitors of ALKs as drug targets in tumor and stem cells.

Proteomic Analysis of Biomphalaria glabrata Hemocytes During in vitro Encapsulation of Schistosoma mansoni Sporocysts

Circulating hemocytes of the snail Biomphalaria glabrata, a major intermediate host for the blood fluke Schistosoma mansoni, represent the primary immune effector cells comprising the host's internal defense system. Within hours of miracidial entry into resistant B. glabrata strains, hemocytes infiltrate around developing sporocysts forming multi-layered cellular capsules that results in larval death, typically within 24–48 h post-infection. Using an in vitro model of hemocyte-sporocyst encapsulation that recapitulates in vivo events, we conducted a comparative proteomic analysis on the responses of hemocytes from inbred B. glabrata strains during the encapsulation of S. mansoni primary sporocysts. This was accomplished by a combination of Laser-capture microdissection (LCM) to isolate sections of hemocyte capsules both in the presence and absence of sporocysts, in conjunction with mass spectrometric analyses to establish protein expression profiles. Comparison of susceptible NMRI snail hemocytes in the presence and absence of sporocysts revealed a dramatic downregulation of proteins in during larval encapsulation, especially those involved in protein/CHO metabolism, immune-related, redox and signaling pathways. One of 4 upregulated proteins was arginase, competitor of nitric oxide synthetase and inhibitor of larval-killing NO production. By contrast, when compared to control capsules, sporocyst-encapsulating hemocytes of resistant BS-90 B. glabrata exhibited a more balanced profile with enhanced expression of shared proteins involved in protein synthesis/processing, immunity, and redox, and unique expression of anti-microbial/anti-parasite proteins. A final comparison of NMRI and BS-90 host hemocyte responses to co-cultured sporocysts demonstrated a decrease or downregulation of 77% of shared proteins by NMRI cells during encapsulation compared to those of the BS-90 strain, including lipopolysaccharide-binding protein, thioredoxin reductase 1 and hemoglobins 1 and 2. Overall, using this in vitro model, results of our proteomic analyses demonstrate striking differences in proteins expressed by susceptible NMRI and resistant BS-90 snail hemocytes to S. mansoni sporocysts during active encapsulation, with NMRI hemocytes exhibiting extensive downregulation of protein expression and a lower level of constitutively expressed immune-relevant proteins (e.g., FREP2) compared to BS-90. Our data suggest that snail strain differences in hemocyte protein expression during the encapsulation process account for observed differences in their cytotoxic capacity to interact with and kill sporocysts.

Decreased expression of ZO-1 is associated with tumor metastases in liver cancer

Certain types of cancer exhibit downregulated expression of zonula occludens-1 (ZO-1), which serves an important function in tumor progression; however, the underlying molecular mechanisms that lead to this downregulation in cancer remain unclear. In the present study, the expression of ZO-1 in liver cancer (LC) tissues was investigated. Western blot and reverse transcription-quantitative polymerase chain reaction assays were used to detect the expression of ZO-1 protein and mRNA in LC tissues and paired adjacent non-tumorous tissues. The results indicated that, compared with non-tumorous tissues, the expression of ZO-1 was significantly downregulated at the protein (P<0.001) and mRNA (P=0.006) levels in LC tissue samples. In addition, various cellular and molecular methods were applied, including MTT, colony formation, flow cytometry and Transwell assays. The results indicated that overexpression of ZO-1 inhibited cell viability, proliferation and migration, and induced G₀/G₁ phase arrest in vitro.

High prevalence of Gammapapillomaviruses (Gamma-PVs) in pre-malignant cutaneous lesions of immunocompetent individuals using a new broad-spectrum primer system, and identification of HPV210, a novel Gamma-PV type

Genus Gammapapillomavirus (Gamma-PV) is the most diverse and largest clade within the Papillomaviridae family. A novel set of degenerate primers targeting the E1 gene was designed and further used in combination with the well-known CUT PCR assay to assess HPV prevalence and genus distribution in a variety of cutaneous samples from 448 immunocompetent individuals. General HPV, Gamma-PV and mixed infections prevalence were significantly higher in actinic keratosis with respect to benign and malignant neoplasms, respectively (p = 0.0047, p = 0.0172, p = 0.00001). Gamma-PVs were significantly more common in actinic keratosis biopsies than Beta- and Alpha-PVs (p = 0.002). The full-length genome sequence of a novel putative Gamma-PV type was amplified by 'hanging droplet' long-range PCR and cloned. The novel virus, designated HPV210, clustered within species Gamma-12. This study provides an additional tool enabling detection of HPV infections in skin and adds new insights about possible early roles of Gamma-PVs in the development of cutaneous malignant lesions.

65 YEARS OF THE DOUBLE HELIX: One gene, many endocrine and metabolic syndromes: PTEN-opathies and precision medicine

An average of 10% of all cancers (range 1-40%) are caused by heritable mutations and over the years have become powerful models for precision medicine practice. Furthermore, such cancer predisposition genes for seemingly rare syndromes have turned out to help explain mechanisms of sporadic carcinogenesis and often inform normal development. The tumor suppressor PTEN encodes a ubiquitously expressed phosphatase that counteracts the PI3K/AKT/mTOR cascade - one of the most critical growth-promoting signaling pathways. Clinically, individuals with germline PTEN mutations have diverse phenotypes and fall under the umbrella term PTEN hamartoma tumor syndrome (PHTS). PHTS encompasses four clinically distinct allelic overgrowth syndromes, namely Cowden, Bannayan-Riley-Ruvalcaba, Proteus and Proteus-like syndromes. Relatedly, mutations in other genes encoding components of the PI3K/AKT/mTOR pathway downstream of PTEN also predispose patients to partially overlapping clinical manifestations, with similar effects as PTEN malfunction. We refer to these syndromes as 'PTEN-opathies.' As a tumor suppressor and key regulator of normal development, PTEN dysfunction can cause a spectrum of phenotypes including benign overgrowths, malignancies, metabolic and neurodevelopmental disorders. Relevant to clinical practice, the identification of PTEN mutations in patients not only establishes a PHTS molecular diagnosis, but also informs on more accurate cancer risk assessment and medical management of those patients and affected family members. Importantly, timely diagnosis is key, as early recognition allows for preventative measures such as high-risk screening and surveillance even prior to cancer onset. This review highlights the translational impact that the discovery of PTEN has had on the diagnosis, management and treatment of PHTS.

Increased systemic zonula occludens 1 associated with inflammation and independent biomarker in patients with hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is a frequent type of primary liver cancer, and its prevalence is increasing worldwide. Indeed, the underlying molecular mechanism is not well understood. Previous studies have shown evidence that tight junction (TJ) components were correlated with carcinogenesis and tumor development. Our aims were to determine the serum levels of tight junction protein Zonula Occludens (ZO)-1 and an inflammatory marker such as high-sensitive C-reactive protein (hs-CRP) in HCC patients compared to healthy volunteers and also to identify the association between ZO-1 and inflammation in HCC.

Methods

Thirty HCC patients and 30 healthy volunteers were recruited in the current study. Clinical data regarding child class, BCLC staging, the number of lesions, tumor size, absence or presence of metastasis, cirrhosis and hepatitis infection were also collected in HCC patients. Plasma ZO-1 and serum hsCRP were analyzed by EIA and ELISA respectively and biochemical parameters by autoanalyser (AU680 Beckman Coulter, USA). Furthermore, hepatic ZO-1 protein expression and tissue localization were examined.

Results

Compared to healthy individuals, the serum levels of bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT) and alkaline phosphatase (ALP) were elevated significantly (P < 0.0001) whilst serum albumin level was significantly (P < 0.0001) decreased in HCC patients. Furthermore, tight junction protein ZO-1 concentration was significantly elevated in HCC patients compared to control subjects (648 ± 183.8 vs. 396.4 ± 135.8 pg/ml, respectively; P < 0.0001). Serum hsCRP level was also significantly increased in HCC patients compared to control subjects (17.25 ± 3.57 vs. 5.54 ± 2.62 mg/L, respectively; P < 0.0001). Moreover, decreased protein expression of ZO-1 was found in liver tissue obtained from HCC patients.

Conclusion

Our findings show for the first time that the systemic concentration of ZO-1 was significantly elevated in HCC patients and is positively correlated with inflammatory markers. Thus, the current study showing evidence that inflammation promotes plasma ZO-1 concentration and raises the possibility that it could be used as a potential diagnostic biomarker for HCC progression.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4484-5) contains supplementary material, which is available to authorized users.

α6-Integrin alternative splicing: distinct cytoplasmic variants in stem cell fate specification and niche interaction

α6-Integrin subunit (also known as CD49f) is a stemness signature that has been found on the plasma membrane of more than 30 stem cell populations. A growing body of studies have focused on the critical role of α6-containing integrins (α6β1 and α6β4) in the regulation of stem cell properties, lineage-specific differentiation, and niche interaction. α6-Integrin subunit can be alternatively spliced at the post-transcriptional level, giving rise to divergent isoforms which differ in the cytoplasmic and/or extracellular domains. The cytoplasmic domain of integrins is an important functional part of integrin-mediated signals. Structural changes in the cytoplasmic domain of α6 provide an efficient means for the regulation of stem cell responses to biochemical stimuli and/or biophysical cues in the stem cell niche, thus impacting stem cell fate determination. In this review, we summarize the current knowledge on the structural variants of the α6-integrin subunit and spatiotemporal expression of α6 cytoplasmic variants in embryonic and adult stem/progenitor cells. We highlight the roles of α6 cytoplasmic variants in stem cell fate decision and niche interaction, and discuss the potential mechanisms involved. Understanding of the distinct functions of α6 splicing variants in stem cell biology may inform the rational design of novel stem cell-based therapies for a range of human diseases.

Phosphorylation of the Unique C-Terminal Tail of the Alpha Isoform of the Scaffold Protein SH2B1 Controls the Ability of SH2B1α To Enhance Nerve Growth Factor Function

The scaffold protein SH2B1, a major regulator of body weight, is recruited to the receptors of multiple cytokines and growth factors, including nerve growth factor (NGF). The β isoform but not the α isoform of SH2B1 greatly enhances NGF-dependent neurite outgrowth of PC12 cells. Here, we asked how the unique C-terminal tails of the α and β isoforms modulate SH2B1 function. We compared the actions of SH2B1α and SH2B1β to those of the N-terminal 631 amino acids shared by both isoforms. In contrast to the β tail, the α tail inhibited the ability of SH2B1 to both cycle through the nucleus and enhance NGF-mediated neurite outgrowth, gene expression, phosphorylation of Akt and phospholipase C-gamma (PLC-γ), and autophosphorylation of the NGF receptor TrkA. These functions were restored when Tyr753 in the α tail was mutated to phenylalanine. We provide evidence that TrkA phosphorylates Tyr753 in SH2B1α, as well as tyrosines 439 and 55 in both SH2B1α and SH2B1β. Finally, coexpression of SH2B1α but not SH2B1α with a mutation of Y to F at position 753 (Y753F) inhibited the ability of SH2B1β to enhance neurite outgrowth. These results suggest that the C-terminal tails of SH2B1 isoforms are key determinants of the cellular role of SH2B1. Furthermore, the function of SH2B1α is regulated by phosphorylation of the α tail.

Interference of HTLV-1 Tax Protein with Cell Polarity Regulators: Defining the Subcellular Localization of the Tax-DLG1 Interaction

Human T cell leukemia virus (HTLV)-1 Tax (Tax) protein is very important in viral replication and cell transformation. Tax localizes in the nucleus and cytoplasm in association with organelles. Some activities of Tax depend on interactions with PDZ (PSD-95/Discs Large/Z0-1) domain-containing proteins such as Discs large protein 1 (DLG1) which is involved in cell polarity and proliferation. The DLG1 interaction results in a cytoplasmic co-localization pattern resembling vesicular aggregates, the nature of which is still unknown. To further explore the role of PDZ proteins in HTLV-1 cell transformation, we deeply investigated the Tax-DLG1 association. By fluorescence resonance energy transfer (FRET), we detected, for the first time, the direct binding of Tax to DLG1 within the cell. We showed that the interaction specifically affects the cellular distribution of not only DLG1, but also Tax. After studying different cell structures, we demonstrated that the aggregates distribute into the Golgi apparatus in spatial association with the microtubule-organizing center (MTOC). This study contributes to understand the biological significance of Tax-PDZ interactions.

Natural history of human papillomavirus infection of sun-exposed healthy skin of immunocompetent individuals over three climatic seasons and identification of HPV209, a novel betapapillomavirus

We present the first longitudinal study reporting the natural history of human papillomavirus (HPV) infection in sun-exposed skin of healthy individuals living in a geographical area in which solar UV radiation is influenced by the ozone content of the atmosphere. During three climatic seasons, skin swab samples were obtained from 78 healthy individuals and the prevalence of cutaneous HPVs was assessed with broad-spectrum FAP and CUT primers and determined at 54, 45 and 47 % in spring, summer and winter, respectively. Frequencies of mixed HPV infections were significantly higher in spring with respect to summer and winter (P=0.02). Seventy-one different HPV types/putative types were identified. While 62 volunteers were HPV-infected in at least one season, 23 had persistent infections. β-PVs (β-1) were the most prevalent and persistent. Age was associated with both the infection status (P=0.01) and the type of HPV infection (no infection, indeterminate/transient, persistent P=0.02). The molecular/phylogenetic analysis of the newly identified β-PV, officially designated as HPV209, showed that the virus has a typical genomic organization of cutaneous HPVs with five early (E6, E7, E1, E2 and E4) and two late genes (L2 and L1), which clusters to the species β-2. This provides useful data on cutaneous HPV infections in high UV-exposed regions.

Clinical Implications for Germline PTEN Spectrum Disorders

Patients with PTEN hamartoma tumor syndrome (PHTS) may present to a variety of different subspecialties with benign and malignant clinical features. They have increased lifetime risks of breast, endometrial, thyroid, renal, and colon cancers, as well as neurodevelopmental disorders such as autism spectrum disorder. Patients and affected family members can be offered gene-directed surveillance and management. Patients who are unaffected can be spared unnecessary investigations. With longitudinal follow-up, we are likely to identify other non-cancer manifestations associated with PHTS such as metabolic, immunologic, and neurologic features.

Proteomic mapping of cytosol-facing outer mitochondrial and ER membranes in living human cells by proximity biotinylation

The cytosol-facing membranes of cellular organelles contain proteins that enable signal transduction, regulation of morphology and trafficking, protein import and export, and other specialized processes. Discovery of these proteins by traditional biochemical fractionation can be plagued with contaminants and loss of key components. Using peroxidase-mediated proximity biotinylation, we captured and identified endogenous proteins on the outer mitochondrial membrane (OMM) and endoplasmic reticulum membrane (ERM) of living human fibroblasts. The proteomes of 137 and 634 proteins, respectively, are highly specific and highlight 94 potentially novel mitochondrial or ER proteins. Dataset intersection identified protein candidates potentially localized to mitochondria-ER contact sites. We found that one candidate, the tail-anchored, PDZ-domain-containing OMM protein SYNJ2BP, dramatically increases mitochondrial contacts with rough ER when overexpressed. Immunoprecipitation-mass spectrometry identified ribosome-binding protein 1 (RRBP1) as SYNJ2BP's ERM binding partner. Our results highlight the power of proximity biotinylation to yield insights into the molecular composition and function of intracellular membranes.

Comparative Study of the Collective Dynamics of Proteins and Inorganic Nanoparticles

Molecular dynamics simulations of ubiquitin in water/glycerol solutions are used to test the suggestion by Karplus and coworkers that proteins in their biologically active state should exhibit a dynamics similar to 'surface-melted' inorganic nanoparticles (NPs). Motivated by recent studies indicating that surface-melted inorganic NPs are in a 'glassy' state that is an intermediate dynamical state between a solid and liquid, we probe the validity and significance of this proposed analogy. In particular, atomistic simulations of ubiquitin in solution based on CHARMM36 force field and pre-melted Ni NPs (Voter-Chen Embedded Atom Method potential) indicate a common dynamic heterogeneity, along with other features of glass-forming (GF) liquids such as collective atomic motion in the form of string-like atomic displacements, potential energy fluctuations and particle displacements with long range correlations ('colored' or 'pink' noise), and particle displacement events having a power law scaling in magnitude, as found in earthquakes. On the other hand, we find the dynamics of ubiquitin to be even more like a polycrystalline material in which the α-helix and β-sheet regions of the protein are similar to crystal grains so that the string-like collective atomic motion is concentrated in regions between the α-helix and β-sheet domains.

Mechanisms of Intestinal Epithelial Barrier Dysfunction by Adherent-Invasive Escherichia coli

Pathobiont expansion, such as that of adherent-invasive Escherichia coli (AIEC), is an emerging factor associated with inflammatory bowel disease. The intestinal epithelial barrier is the first line of defense against these pathogens. Inflammation plays a critical role in altering the epithelial barrier and is a major factor involved in promoting the expansion and pathogenesis of AIEC. AIEC in turn can exacerbate intestinal epithelial barrier dysfunction by targeting multiple elements of the barrier. One critical element of the epithelial barrier is the tight junction. Increasing evidence suggests that AIEC may selectively target protein components of tight junctions, leading to increased barrier permeability. This may represent one mechanism by which AIEC could contribute to the development of inflammatory bowel disease. This review article discusses potential mechanisms by which AIEC can disrupt epithelial tight junction function and intestinal barrier function.

The differential role of HTRA1 in HPV-positive and HPV-negative cervical cell line proliferation

BACKGROUND

High-risk human papillomaviruses (HPVs) are strongly associated with the development of some malignancies. The E6 and E7 viral oncoproteins are the primary proteins responsible for cell homeostasis alteration and immortalization. Furthermore, the E6 protein from high-risk HPVs can interact with the PDZ (PSD-90/Dlg/ZO-1) domains of cellular proteins, triggering cell transformation. One protein that is associated with pathological conditions and has a PDZ domain is the protease HTRA1 (high temperature requirement 1). This protein is poorly expressed in some cancers, suggesting a tumor suppressor role. The aim of this study was to evaluate the effect of HTRA1 overexpression in HPV16-positive (CasKi) and HPV-negative (C33) cervical cell lines.

METHODS

The cells were transfected with a vector containing the HTRA1 ORF or an empty vector. HTRA1 overexpression was confirmed by qRT-PCR. The cells were subjected to cell proliferation, colony formation, apoptosis and cell cycle assays.

RESULTS

C33 cells expressing HTRA1 grew significantly fewer colonies and showed less proliferation than cells without HTRA1 expression. In contrast, in the CasKi cells overexpressing HTRA1, there was an increase in the cell growth rate and in the colonies density compared to cells expressing low levels of HTRA1. An apoptosis assay showed that HTRA1 does not interfere with the apoptosis rate in these cells. A cell cycle immunofluorescence assay revealed more CasKi cells overexpressing HTRA1 in the S phase and more C33 HTRA1-transfected cells in the G0/G1 phase, suggesting that HTRA1 plays different roles in the cell cycle progression of these cells.

CONCLUSIONS

HTRA1 overexpression prevents cell proliferation in the HPV-negative cell line and increases cell proliferation in the HPV-positive cell line. Although the E6/HTRA1 interaction has already been described in the literature, more studies are required to confirm whether the present functional findings are a result of this interaction.