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Background: Neuropilin-1 (NRP1) is a transmembrane protein involved in surface receptor complexes for a variety of extracellular signals. NRP1 expression in human cancers is associated with prominent angiogenesis and advanced progression stage. However, the molecular mechanisms underlying NRP1 activity in the tumor microenvironment remain unclear. Notably, diffusible forms of NRP1 in the extracellular space have been reported, but their functional role is poorly understood. Methods: Extracellular vesicles (EV) were isolated from conditioned media of diverse cancer cells. The quality of exosome-enriched preparations was validated by the presence of specific markers in western blotting, as well as by light scattering and nanoparticle tracking analysis. Wound healing, transwell, and digital real-time migration assays were carried out to assess the activity of cancer cell-derived exosomes in the regulation of endothelial cells. RNA interference was applied to obtain NRP1 knock-down, and cDNA transfer to achieve its overexpression, in exosome-releasing cells. The micro-RNA profile carried by exosomes was investigated by Next Generation Sequencing. miRNA-Scope in situ hybridization was used to assess the transfer of miRNA exosome cargo to target cells, and immunofluorescence analysis revealed expression regulation of targeted proteins. miRNA activity was blocked by the use of specific antago-miRs. Results: In this study, we show that diverse human cancer cells release NRP1 embedded in exosome-like small extracellular vesicles, which mediate a previously unknown NRP1-dependent paracrine signaling mechanism regulating endothelial cell migration. By transcriptomic analysis of the cargo of NRP1-loaded exosomes, we found a significant enrichment of miR-210-3p, known to promote tumor angiogenesis. Gene knock-down and overexpression experiments demonstrated that the loading of miR-210-3p into exosomes is dependent on NRP1. Data furthermore indicate that the exosomes released through this NRP1-driven mechanism effectively transfer miR-210-3p to human endothelial cells, causing paracrine downregulation of the regulatory cue ephrin-A3 and promotion of cell migration. The mechanistic involvement of miR-210-3p in this pathway was confirmed by applying a specific antago-miR. Conclusions: In sum, we unveiled a previously unknown NRP1-dependent paracrine signaling mechanism, mediated by the loading of pro-angiogenic miR-210-3p in exosomes released by cancer cells, which underscores the relevance of NRP1 in controlling the tumor microenvironment. [ABSTRACT FROM AUTHOR]

Abstract In esophageal adenocarcinoma, the presence of lymph node metastases predicts patients' survival even after curative resection. Currently, there is no highly accurate marker for detecting the presence of lymph node metastasis. The SEMA3F/NRP2 axis was initially characterized in axon guidance and recent evidence has revealed its significant involvement in lymphangiogenesis, angiogenesis, and carcinogenesis. Hence, the objective of this study was to elucidate the roles of SEMA3F and its receptor NRP2 in esophageal adenocarcinoma. We conducted an immunohistochemical evaluation of SEMA3F and NRP2 protein expression in 776 patients with esophageal adenocarcinoma who underwent Ivor-Lewis esophagectomy at the University Hospital of Cologne. Total and positive cancer cell counts were digitally analyzed using QuPath and verified by experienced pathologists to ensure accuracy. Positive expression was determined as a cell percentage exceeding the 50th percentile threshold. In our cohort, patients exhibiting SEMA3F positive expression experience significantly lower pT- and pN-stages. In contrast, positive NRP2 expression is associated with the presence of lymph node metastases. Survival analyses showed that the expression status of NRP2 had no impact on patient survival. However, SEMA3F positivity was associated with a favorable patient survival outcome (median OS: 38.9 vs. 26.5 months). Furthermore, SEMA3F could be confirmed as an independent factor for better patient survival in patients with early tumor stage (pT1N0-3: HR = 0.505, p = 0.014, pT1-4N0: HR = 0.664, p = 0.024, pT1N0: HR = 0.483, p = 0.040). In summary, SEMA3F emerges as an independent predictor for a favorable prognosis in patients with early-stage esophageal adenocarcinoma. Additionally, NRP2 expression is linked to a higher risk of lymph node metastases occurrence. We hypothesize that low SEMA3F expression could identify patients with early-stage tumors who might benefit from more aggressive treatment options or intensified follow-up. Furthermore, SEMA3F and its associated pathways should be explored as potential tumor-suppressing agents.

In esophageal adenocarcinoma, the presence of lymph node metastases predicts patients' survival even after curative resection. Currently, there is no highly accurate marker for detecting the presence of lymph node metastasis. The SEMA3F/NRP2 axis was initially characterized in axon guidance and recent evidence has revealed its significant involvement in lymphangiogenesis, angiogenesis, and carcinogenesis. Hence, the objective of this study was to elucidate the roles of SEMA3F and its receptor NRP2 in esophageal adenocarcinoma. We conducted an immunohistochemical evaluation of SEMA3F and NRP2 protein expression in 776 patients with esophageal adenocarcinoma who underwent Ivor-Lewis esophagectomy at the University Hospital of Cologne. Total and positive cancer cell counts were digitally analyzed using QuPath and verified by experienced pathologists to ensure accuracy. Positive expression was determined as a cell percentage exceeding the 50th percentile threshold. In our cohort, patients exhibiting SEMA3F positive expression experience significantly lower pT- and pN-stages. In contrast, positive NRP2 expression is associated with the presence of lymph node metastases. Survival analyses showed that the expression status of NRP2 had no impact on patient survival. However, SEMA3F positivity was associated with a favorable patient survival outcome (median OS: 38.9 vs. 26.5 months). Furthermore, SEMA3F could be confirmed as an independent factor for better patient survival in patients with early tumor stage (pT1N0-3: HR = 0.505, p = 0.014, pT1-4N0: HR = 0.664, p = 0.024, pT1N0: HR = 0.483, p = 0.040). In summary, SEMA3F emerges as an independent predictor for a favorable prognosis in patients with early-stage esophageal adenocarcinoma. Additionally, NRP2 expression is linked to a higher risk of lymph node metastases occurrence. We hypothesize that low SEMA3F expression could identify patients with early-stage tumors who might benefit from more aggressive treatment options or intensified follow-up. Furthermore, SEMA3F and its associated pathways should be explored as potential tumor-suppressing agents. [ABSTRACT FROM AUTHOR]

Multiple pathogenic mechanisms are found in SARS-CoV2 systemic inflammation. Oxidative stress, altered proteolysis, hypercoagulation, and metabolic disorders are significant in virus-induced lesions. The study aimed to investigate the biochemical mechanism of virus-induced disorders and determine the biochemical features in SARS-CoV2-associated liver damage and intestine lesions. A retrospective case series of ninety-two patients diagnosed with COVID-19 pnemonia. The ACE, α1-proteinase inhibitor, trypsin-like proteinase, and elastase activity were measured. Nitrites level was detected in reaction with Griess reagent. The ELISA kit measured Troponin, C-peptide, leptin, adiponectin, PAR4, and neuropilin level. It was obtained an increase in ACE activity and nitrites ions content in SARS-CoV2 associated patients. The hyperglycemia and an increase in adipose tissue-derived hormones guided the virus-induced metabolic disorders. Proteolysis activation was revealed in SARS-CoV2 pneumonia patients. The found molecular event was accompanied by hyperglycemia induction. Multiorgan lesions manifest in in cardiac failure, which was detected in patients with ARDS. Moreover, high arterial blood pressure in patients with COVID-19 was associated with the hyperglycemia and increased ACE activity and NO ions level. Liver damage was specific for COVID-19-associated patients with severe ARDS and heart failure. Proteolysis overactivation resulting in vasoactive substances imbalance was detected in patients with the intestinal lesions. The obtained data shows the the neuropilin-dependent axis in damage prevalence in the intestine. Metabolic disorders resulting in the growth of adipose-derived tissue hormones, nitrites, and neuropilin levels was triggered by prolonged inflammation. So, the impaired metabolism and SARS-CoV2 associated hyperglycemia influence on SARS-CoV2 multiple mechanisms. Gastrointestinal manifestations in SARS-CoV2 infection was found to be related to various biochemical and molecular tools. ACE2 receptors axis is prevalent for liver damage, but NRP-1 protein (neuropilin), NO derivatives, and adipose tissue-derived hormones are essential for intestinal lesions. [ABSTRACT FROM AUTHOR]

Breast cancer is the most common cancer worldwide and a leading cause of cancer-related deaths in women. The clinical management of breast cancer is further complicated by the heterogeneous nature of the disease, which results in varying prognoses and treatment responses in patients. The semaphorins are a family of proteins with varied roles in development and homoeostasis. They are also expressed in a wide range of human cancers and are implicated as regulators of tumour growth, angiogenesis, metastasis and immune evasion. More recently, semaphorins have been implicated in drug resistance across a range of malignancies. In breast cancer, semaphorins are associated with resistance to endocrine therapy as well as breast cancer chemotherapeutic agents such as taxanes and anthracyclines. This review will focus on the semaphorins involved in breast cancer progression and their association with drug resistance. [ABSTRACT FROM AUTHOR]

Choroidal neovascularization (CNV) is a common ocular pathology that may be associated in a variety of eye diseases. Although intravitreal injection treatment of anti-vascular endothelial growth factor (anti-VEGF) drugs shows significant clinical benefits in CNV treatment, the limitations of the current therapy need to be addressed. The aim of our study was to investigate the potential utility of three C-end Rule (CendR) peptides (RPARPAR, PL3, iRGD) for CNV targeting and to evaluate the efficacy of peptides for treating experimental CNV in mice. We observed that the CendR peptides localize to the CNV lesion sites after intravitreal injection and were mainly found in the outer nuclear cell layer (ONL) of the mouse retina. Interestingly, experimental therapy with tenascin-C (TNC-C) and neuropilin-1 (NRP-1)-targeting PL3 peptide, reduced angiogenesis and decreased vascular leakage. The results suggest that PL3 and potentially other CendR peptides could serve as affinity targeting ligands and therapeutics for ocular diseases that involve pathological CNV. [Display omitted] [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. NRP1-4 is a first-in-class compound uncoupling the neuropilin 1–vascular endothelial growth factor A signaling axis to reduce voltage-gated ion channel function, neuronal excitability, and synaptic activity that curbs chronic pain. Vascular endothelial growth factor A (VEGF-A) is a pronociceptive factor that causes neuronal sensitization and pain. We reported that blocking the interaction between the membrane receptor neuropilin 1 (NRP1) and VEGF-A–blocked VEGF-A–mediated sensory neuron hyperexcitability and reduced mechanical hypersensitivity in a rodent chronic neuropathic pain model. These findings identified the NRP1-VEGF-A signaling axis for therapeutic targeting of chronic pain. In an in-silico screening of approximately 480 K small molecules binding to the extracellular b1b2 pocket of NRP1, we identified 9 chemical series, with 6 compounds disrupting VEGF-A binding to NRP1. The small molecule with greatest efficacy, 4′-methyl-2′-morpholino-2-(phenylamino)-[4,5′-bipyrimidin]-6(1H)-one, designated NRP1-4, was selected for further evaluation. In cultured primary sensory neurons, VEGF-A enhanced excitability and decreased firing threshold, which was blocked by NRP1-4. In addition, NaV1.7 and CaV2.2 currents and membrane expression were potentiated by treatment with VEGF-A, and this potentiation was blocked by NRP1-4 cotreatment. Neuropilin 1-4 reduced VEGF-A–mediated increases in the frequency and amplitude of spontaneous excitatory postsynaptic currents in dorsal horn of the spinal cord. Neuropilin 1-4 did not bind to more than 300 G-protein-coupled receptors and receptors including human opioids receptors, indicating a favorable safety profile. In rats with spared nerve injury–induced neuropathic pain, intrathecal administration of NRP1-4 significantly attenuated mechanical allodynia. Intravenous treatment with NRP1-4 reversed both mechanical allodynia and thermal hyperalgesia in rats with L5/L6 spinal nerve ligation–induced neuropathic pain. Collectively, our findings show that NRP1-4 is a first-in-class compound targeting the NRP1-VEGF-A signaling axis to control voltage-gated ion channel function, neuronal excitability, and synaptic activity that curb chronic pain. [ABSTRACT FROM AUTHOR]

The new coronavirus infection (COVID-19) pandemic caused by SARS-CoV-2 has many times surpassed the epidemics caused by SARS-CoV and MERS-CoV. The reason for this was the presence of sites in the protein sequence of SARS-CoV-2 that provide interaction with a broader range of receptor proteins on the host cell surface. In this review, we consider both already known receptors common to SARS-CoV and SARS-CoV-2 and new receptors specific to SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Billions of years of co-evolution has made mitochondria central to the eukaryotic cell and organism life playing the role of cellular power plants, as indeed they are involved in most, if not all, important regulatory pathways. Neurological disorders depending on impaired mitochondrial function or homeostasis can be caused by the misregulation of "endogenous players", such as nuclear or cytoplasmic regulators, which have been treated elsewhere. In this review, we focus on how exogenous agents, i.e., viral pathogens, or unbalanced microbiota in the gut-brain axis can also endanger mitochondrial dynamics in the central nervous system (CNS). Neurotropic viruses such as Herpes, Rabies, West-Nile, and Polioviruses seem to hijack neuronal transport networks, commandeering the proteins that mitochondria typically use to move along neurites. However, several neurological complications are also associated to infections by pandemic viruses, such as Influenza A virus and SARS-CoV-2 coronavirus, representing a relevant risk associated to seasonal flu, coronavirus disease-19 (COVID-19) and "Long-COVID". Emerging evidence is depicting the gut microbiota as a source of signals, transmitted via sensory neurons innervating the gut, able to influence brain structure and function, including cognitive functions. Therefore, the direct connection between intestinal microbiota and mitochondrial functions might concur with the onset, progression, and severity of CNS diseases. [ABSTRACT FROM AUTHOR]

Abstract Background Triple-negative breast cancers (TNBC) have a relatively poor prognosis and responses to targeted therapies. Between 25 and 39% of TNBCs are claudin-low, a poorly differentiated subtype enriched for mesenchymal, stem cell and mitogen-activated signaling pathways. We investigated the role of the cell-surface co-receptor NRP1 in the biology of claudin-low TNBC. Methods The clinical prognostic value of NRP1 was determined by Kaplan–Meier analysis. GSVA analysis of METABRIC and Oslo2 transcriptomics datasets was used to correlate NRP1 expression with claudin-low gene signature scores. NRP1 siRNA knockdown was performed in MDA-MB-231, BT-549, SUM159 and Hs578T claudin-low cells and proliferation and viability measured by live cell imaging and DNA quantification. In SUM159 orthotopic xenograft models using NSG mice, NRP1 was suppressed by shRNA knockdown or systemic treatment with the NRP1-targeted monoclonal antibody Vesencumab. NRP1-mediated signaling pathways were interrogated by protein array and Western blotting. Results High NRP1 expression was associated with shorter relapse- and metastasis-free survival specifically in ER-negative BrCa cohorts. NRP1 was over-expressed specifically in claudin-low clinical samples and cell lines, and NRP1 knockdown reduced proliferation of claudin-low cells and prolonged survival in a claudin-low orthotopic xenograft model. NRP1 inhibition suppressed expression of the mesenchymal and stem cell markers ZEB1 and ITGA6, respectively, compromised spheroid-initiating capacity and exerted potent anti-tumor effects on claudin-low orthotopic xenografts (12.8-fold reduction in endpoint tumor volume). NRP1 was required to maintain maximal RAS/MAPK signaling via EGFR and PDGFR, a hallmark of claudin-low tumors. Conclusions These data implicate NRP1 in the aggressive phenotype of claudin-low breast cancer and offer a novel targeted therapeutic approach to this poor prognosis subtype.

Background: Angiotensin-converting enzyme 2 (ACE2) is known as the major viral entry site for SARS-CoV-2. However, viral tissue tropism and high rate of infectivity do not directly correspond with the level of ACE2 expression in the organs. It may suggest involvement of other receptors or accessory membrane proteins in SARSCoV-2 cell entry. Methods and Results: A systematic search was carried out in PubMed/Medline, EMBASE, and Cochrane Library for studies reporting SARS-CoV-2 cell entry. We used a group of the MeSH terms including "cell entry", "surface receptor", "ACE2", and "SARS-CoV-2". We reviewed all selected papers published in English up to end of February 2022. We found several receptors or auxiliary membrane proteins (including CD147, NRP-1, CD26, AGTR2, Band3, KREMEN1, ASGR1, ANP, TMEM30A, CLEC4G, and LDLRAD3) along with ACE2 that facilitate virus entry and transmission. Expression of Band3 protein on the surface of erythrocytes and evidence of binding with S protein of SARS-CoV-2 may explain asymptomatic hypoxemia during COVID19 infection. The variants of SARS-CoV-2 including the B.1.1.7 (Alpha), B.1.617.1 (Kappa), B.1.617.2 (Delta), B.1.617.2+ (Delta+), and B.1.1.529 (Omicron) may have different potency to bond with these receptors. Conclusions: The high rate of infectivity of SARS-CoV-2 may be due to its ability to enter the host cell through a group of cell surface receptors. These receptors are potential targets to develop novel therapeutic agents for SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Semaphorins (Semas), which belongs to the axonal guidance molecules, include 8 classes and could affect axon growth in the nervous system. Recently, semaphorins were found to regulate other pathophysiological processes, such as immune response, oncogenesis, tumor angiogenesis, and bone homeostasis, through binding with their plexin and neuropilin receptors. In this review, we summarized the detailed role of semaphorins and their receptors in the pathological progression of various cardiovascular diseases (CVDs), highlighting that semaphorins may be potential therapeutic targets and novel biomarkers for CVDs. [ABSTRACT FROM AUTHOR]

Semaphorins are a large family of secreted and/or transmembrane proteins, originally identified as proteins that function in axon guidance during neuronal development. However, semaphorins play crucial roles in other physiological and pathological processes, including immune responses, angiogenesis, maintenance of tissue homeostasis, and cancer progression. Class IV semaphorins may be present as transmembrane and soluble forms and are implicated in the pathogenesis of various diseases. This review discusses recent progress on the roles of class IV semaphorins determined by clinical and experimental pathology studies. [ABSTRACT FROM AUTHOR]

Non-small cell lung cancer (NSCLC) is an aggressive lung cancer accounting for approximately 85% of all lung cancer patients. For the patients with Stages IIIA, IIIB, and IIIC, the 5-year survival is low though with the combination with radiotherapy and chemotherapy. In addition, the occurrence of tumor cells (repopulated tumors) that survive irradiation remains a challenge. In our previous report, we subcloned the radiation-surviving tumor cells (IR cells) using the human NSCLC cell line, H1299, and found that the expression of neuropilin-1 (NRP-1) was upregulated in IR cells by the microarray analysis. Here, we investigated the contribution of neuropilin-1 to changes in the characteristics of IR cells. Although there were no differences in angiogenic activity in the tube formation assay between parental and IR cells, the cell motility was increased in IR cells compared to parental cells in the cell migration assay. This enhanced cell motility was suppressed by pretreatment with anti-NRP-1 antibody. Although further studies are necessary to identify other molecules associated with NRP-1, the increase in cellular motility in IR cells might be due to the contribution of NRP-1. Inhibition of NRP-1 would help control tumor malignancy in radiation-surviving NSCLC.

The term “molecular ZIP (or area) codes” refers to an originally hypothetical system of cell adhesion molecules that would control cell trafficking in the body. Subsequent discovery of the integrins, cadherins, and other cell adhesion molecules confirmed this hypothesis. The recognition system encompassing integrins and their ligands came particularly close to fulfilling the original ZIP code hypothesis, as multiple integrins with closely related specificities mediate cell adhesion by binding to an RGD or related sequence in various extracellular matrix proteins. Diseased tissues have their own molecular addresses that, although not necessarily involved in cell trafficking, can be made use of in targeted drug delivery. This article discusses the molecular basis of ZIP codes and the extensive effort under way to harness themfor drug delivery purposes. [ABSTRACT FROM AUTHOR]

Viral internalization is aided by host cell surface receptors. In the case of SARS-CoV-2 and SARS-CoV, the primary host receptor is the angiotensin-converting enzyme 2 (ACE2). Considering the disparities in the transmission rate and viral tropism of the two coronaviruses, additional host factors were suspected. Recently, a novel host factor for SARS-CoV-2 entry, neuropilin-1 (NRP-1) has been identified. These receptors potentiate viral infection in the presence of other host factors like ACE2. Through its C-end rule (CendR) motif exposed following furin processing, the SARS-CoV-2 spike protein binds to the CendR pocket of NRP-1 and achieves cell entry through endocytosis. The binding of SARS-CoV-2 spike protein to the NRP-1 receptor interferes with the docking of its endogenous ligand VEGF-A, signaling that would otherwise promote nociception. This review looks at the function of neuropilins and how it contributes to SARS-CoV-2 infection and nociception.

Tumor-associated macrophages (TAMs) exert profound influence over breast cancer progression, promoting immunosuppression, angiogenesis, and metastasis. Neuropilin-2 (NRP2), consisting of the NRP2a and NRP2b isoforms, is a co-receptor for heparin-binding growth factors including VEGF-C and Class 3 Semaphorins. Selective upregulation in response to environmental stimuli and independent signaling pathways endow the NRP2 isoforms with unique functionality, with NRP2b promoting increased Akt signaling via receptor tyrosine kinases including VEGFRs, MET, and PDGFR. Although NRP2 has been shown to regulate macrophage/TAM biology, the role of the individual NRP2a/NRP2b isoforms in TAMs has yet to be evaluated. Using transcriptional profiling and spectral flow cytometry, we show that NRP2 isoform expression was significantly higher in TAMs from murine mammary tumors. NRP2a/NRP2b levels in human breast cancer metastasis were dependent upon the anatomic location of the tumor and significantly correlated with TAM infiltration in both primary and metastatic breast cancers. We define distinct phenotypes of NRP2 isoform-expressing TAMs in mouse models of breast cancer and within malignant pleural effusions from breast cancer patients which were exclusive of neuropilin-1 expression. Genetic depletion of either NRP2 isoform in macrophages resulted in a dramatic reduction of LPS-induced IL-10 production, defects in phagosomal processing of apoptotic breast cancer cells, and increase in cancer cell migration following co-culture. By contrast, depletion of NRP2b, but not NRP2a, inhibited production of IL-6. These results suggest that NRP2 isoforms regulate both shared and unique functionality in macrophages and are associated with distinct TAM subsets in breast cancer. [ABSTRACT FROM AUTHOR]

Vascular endothelial growth factors (VEGFs) are the key regulators of blood and lymphatic vessels' formation and function. Each of the proteins from the homologous family VEGFA, VEGFB, VEGFC and VEGFD employs a core cysteine-knot structural domain for the specific interaction with one or more of the cognate tyrosine kinase receptors. Additional diversity is exhibited by the involvement of neuropilins–transmembrane co-receptors, whose b1 domain contains the binding site for the C-terminal sequence of VEGFs. Although all relevant isoforms of VEGFs that interact with neuropilins contain the required C-terminal Arg residue, there is selectivity of neuropilins and VEGF receptors for the VEGF proteins, which is reflected in the physiological roles that they mediate. To decipher the contribution made by the C-terminal sequences of the individual VEGF proteins to that functional differentiation, we determined structures of molecular complexes of neuropilins and VEGF-derived peptides and examined binding interactions for all neuropilin-VEGF pairs experimentally and computationally. While X-ray crystal structures and ligand-binding experiments highlighted similarities between the ligands, the molecular dynamics simulations uncovered conformational preferences of VEGF-derived peptides beyond the C-terminal arginine that contribute to the ligand selectivity of neuropilins. The implications for the design of the selective antagonists of neuropilins' functions are discussed. [ABSTRACT FROM AUTHOR]

Viruses are the simplest of pathogens, but possess sophisticated molecular mechanisms to manipulate host behavior, frequently utilizing molecular mimicry. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been shown to bind to the host receptor neuropilin-1 in order to gain entry into the cell. To do this, the virus utilizes its spike protein polybasic cleavage site (PCS), which mimics the CendR motif of neuropilin-1’s endogenous ligands. In addition to facilitating cell entry, binding to neuropilin-1 has analgesic effects. We discuss the potential impact of neuropilin-1 binding by SARS-CoV-2 in ameliorating sickness behavior of the host, and identify a convergent evolutionary strategy of PCS cleavage and subsequent neuropilin binding in other human viruses. In addition, we discuss the evolutionary leap of the ancestor of SARS-COV-2, which involved acquisition of the PCS thus faciliting binding to the neuropilin-1 receptor. Acquisition of the PCS by the ancestor of SARS-CoV-2 appears to have led to pleiotropic beneficial effects including enhancement of cell entry via binding to ACE2, facilitation of cell entry via binding to neuropilin-1, promotion of analgesia, and potentially the formation of decoy epitopes via enhanced shedding of the S1 subunit. Lastly, other potential neuromanipulation strategies employed by SARS-CoV-2 are discussed, including interferon suppression and the resulting reduction in sickness behavior, enhanced transmission through neurally mediated cough induction, and reduction in sense of smell. [ABSTRACT FROM AUTHOR]

Abstract Background Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults, with a median survival of approximately 15 months. Semaphorin 3A (Sema3A), known for its axon guidance and antiangiogenic properties, has been implicated in GBM growth. We hypothesized that Sema3A directly inhibits brain tumor stem cell (BTSC) proliferation and drives invasion via Neuropilin 1 (Nrp1) and Plexin A1 (PlxnA1) receptors. Methods GBM BTSC cell lines were assayed by immunostaining and PCR for levels of Semaphorin 3A (Sema3A) and its receptors Nrp1 and PlxnA1. Quantitative BrdU, cell cycle and propidium iodide labeling assays were performed following exogenous Sema3A treatment. Quantitative functional 2-D and 3-D invasion assays along with shRNA lentiviral knockdown of Nrp1 and PlxnA1 are also shown. In vivo flank studies comparing tumor growth of knockdown versus control BTSCs were performed. Statistics were performed using GraphPad Prism v7. Results Immunostaining and PCR analysis revealed that BTSCs highly express Sema3A and its receptors Nrp1 and PlxnA1, with expression of Nrp1 in the CD133 positive BTSCs, and absence in differentiated tumor cells. Treatment with exogenous Sema3A in quantitative BrdU, cell cycle, and propidium iodide labeling assays demonstrated that Sema3A significantly inhibited BTSC proliferation without inducing cell death. Quantitative functional 2-D and 3-D invasion assays showed that treatment with Sema3A resulted in increased invasion. Using shRNA lentiviruses, knockdown of either NRP1 or PlxnA1 receptors abrogated Sema3A antiproliferative and pro-invasive effects. Interestingly, loss of the receptors mimicked Sema3A effects, inhibiting BTSC proliferation and driving invasion. Furthermore, in vivo studies comparing tumor growth of knockdown and control infected BTSCs implanted into the flanks of nude mice confirmed the decrease in proliferation with receptor KD. Conclusions These findings demonstrate the importance of Sema3A signaling in GBM BTSC proliferation and invasion, and its potential as a therapeutic target.

Tumor-associated macrophages (TAMs) exert profound influence over breast cancer progression, promoting immunosuppression, angiogenesis, and metastasis. Neuropilin-2 (NRP2), consisting of the NRP2a and NRP2b isoforms, is a co-receptor for heparin-binding growth factors including VEGF-C and Class 3 Semaphorins. Selective upregulation in response to environmental stimuli and independent signaling pathways endow the NRP2 isoforms with unique functionality, with NRP2b promoting increased Akt signaling via receptor tyrosine kinases including VEGFRs, MET, and PDGFR. Although NRP2 has been shown to regulate macrophage/TAM biology, the role of the individual NRP2a/NRP2b isoforms in TAMs has yet to be evaluated. Using transcriptional profiling and spectral flow cytometry, we show that NRP2 isoform expression was significantly higher in TAMs from murine mammary tumors. NRP2a/NRP2b levels in human breast cancer metastasis were dependent upon the anatomic location of the tumor and significantly correlated with TAM infiltration in both primary and metastatic breast cancers. We define distinct phenotypes of NRP2 isoform-expressing TAMs in mouse models of breast cancer and within malignant pleural effusions from breast cancer patients which were exclusive of neuropilin-1 expression. Genetic depletion of either NRP2 isoform in macrophages resulted in a dramatic reduction of LPS-induced IL-10 production, defects in phagosomal processing of apoptotic breast cancer cells, and increase in cancer cell migration following co-culture. By contrast, depletion of NRP2b, but not NRP2a, inhibited production of IL-6. These results suggest that NRP2 isoforms regulate both shared and unique functionality in macrophages and are associated with distinct TAM subsets in breast cancer.

Background: Triple-negative breast cancers (TNBC) have a relatively poor prognosis and responses to targeted therapies. Between 25 and 39% of TNBCs are claudin-low, a poorly differentiated subtype enriched for mesenchymal, stem cell and mitogen-activated signaling pathways. We investigated the role of the cell-surface co-receptor NRP1 in the biology of claudin-low TNBC.Methods: The clinical prognostic value of NRP1 was determined by Kaplan-Meier analysis. GSVA analysis of METABRIC and Oslo2 transcriptomics datasets was used to correlate NRP1 expression with claudin-low gene signature scores. NRP1 siRNA knockdown was performed in MDA-MB-231, BT-549, SUM159 and Hs578T claudin-low cells and proliferation and viability measured by live cell imaging and DNA quantification. In SUM159 orthotopic xenograft models using NSG mice, NRP1 was suppressed by shRNA knockdown or systemic treatment with the NRP1-targeted monoclonal antibody Vesencumab. NRP1-mediated signaling pathways were interrogated by protein array and Western blotting.Results: High NRP1 expression was associated with shorter relapse- and metastasis-free survival specifically in ER-negative BrCa cohorts. NRP1 was over-expressed specifically in claudin-low clinical samples and cell lines, and NRP1 knockdown reduced proliferation of claudin-low cells and prolonged survival in a claudin-low orthotopic xenograft model. NRP1 inhibition suppressed expression of the mesenchymal and stem cell markers ZEB1 and ITGA6, respectively, compromised spheroid-initiating capacity and exerted potent anti-tumor effects on claudin-low orthotopic xenografts (12.8-fold reduction in endpoint tumor volume). NRP1 was required to maintain maximal RAS/MAPK signaling via EGFR and PDGFR, a hallmark of claudin-low tumors.Conclusions: These data implicate NRP1 in the aggressive phenotype of claudin-low breast cancer and offer a novel targeted therapeutic approach to this poor prognosis subtype. [ABSTRACT FROM AUTHOR]

Transforming growth factor‐β (TGF‐β) superfamily signaling via their cognate receptors is frequently modified by TGF‐β superfamily co‐receptors. Signaling through SMAD‐mediated pathways may be enhanced or depressed depending on the specific co‐receptor and cell context. This dynamic effect on signaling is further modified by the release of many of the co‐receptors from the membrane to generate soluble forms that are often antagonistic to the membrane‐bound receptors. The co‐receptors discussed here include TβRIII (betaglycan), endoglin, BAMBI, CD109, SCUBE proteins, neuropilins, Cripto‐1, MuSK, and RGMs. Dysregulation of these co‐receptors can lead to altered TGF‐β superfamily signaling that contributes to the pathophysiology of many cancers through regulation of growth, metastatic potential, and the tumor microenvironment. Here we describe the role of several TGF‐β superfamily co‐receptors on TGF‐β superfamily signaling and the impact on cellular and physiological functions with a particular focus on cancer, including a discussion on recent pharmacological advances and potential clinical applications targeting these co‐receptors. Key Findings: TGF‐β superfamily co‐receptors primarily modify ligand interactions with their cognate receptor complexes to enhance or suppress downstream SMAD signaling.Many TGF‐β superfamily co‐receptors are secreted or shed from the cell surface to further modify surface receptor signaling via ligand sequestration.Dysregulation of TGF‐β superfamily co‐receptors contribute to the pathophysiology of many cancers and a rational for the pharmacological targeting of these co‐receptors is on the rise. [ABSTRACT FROM AUTHOR]

Many phylogenetically distant animal viruses, including the new coronavirus severe acute respiratory syndrome coronavirus 2, have surface proteins with polybasic sites that are cleaved by host furin and furin-like proteases. Other than priming certain viral surface proteins for fusion, cleavage generates a carboxyterminal RXXR sequence. This C-end Rule (CendR) motif is known to bind to neuropilin (NRP) receptors on the cell surface. NRPs are ubiquitously expressed, pleiotropic cell surface receptors with important roles in growth factor signaling, vascular biology, and neurobiology, as well as immune homeostasis and activation. The CendR-NRP receptor interaction promotes endocytic internalization and tissue spreading of different cargo, including viral particles. We propose that the interaction between viral surface proteins and NRPs plays an underappreciated and prevalent role in the transmission and pathogenesis of diverse viruses and represents a promising broad-spectrum antiviral target. [ABSTRACT FROM AUTHOR]

Peritoneal carcinomatosis is a major source of morbidity and mortality in patients with advanced abdominal neoplasms. Intraperitoneal chemotherapy (IPC) is an area of intense interest given its efficacy in ovarian cancer. However, IPC suffers from poor drug penetration into peritoneal tumors. As such, extensive cytoreductive surgery is required prior to IPC. Here, we explore the utility of iRGD, a tumor-penetrating peptide, for improved tumor-specific penetration of intraperitoneal compounds and enhanced IPC in mice. Intraperitoneally administered iRGD significantly enhanced penetration of an attached fluorescein into disseminated peritoneal tumor nodules. The penetration was tumor-specific, circulation-independent, and mediated by the neuropilin-binding RXXK tissue-penetration peptide motif of iRGD. Q-iRGD, which fluoresces upon cleavage, including the one that leads to RXXK activation, specifically labeled peritoneal metastases displaying different growth patterns in mice. Importantly, iRGD enhanced intratumoral entry of intraperitoneally co-injected dextran to approximately 300% and doxorubicin to 250%. Intraperitoneal iRGD/doxorubicin combination therapy inhibited the growth of bulky peritoneal tumors and reduced systemic drug toxicity. iRGD delivered attached fluorescein and co-applied nanoparticles deep into fresh human peritoneal metastasis explants. These results indicate that intraperitoneal iRGD co-administration serves as a simple and effective strategy to facilitate tumor detection and improve the therapeutic index of IPC for peritoneal carcinomatosis.

The ongoing coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a global health concern. It is now well established that the spike (S) protein of SARS-CoV-2 interacts with its primary host receptor, the angiotensin converting enzyme 2 (ACE2). Additionally, the interaction of S with the neuropilin (NRP) receptor has been reported to facilitate viral entry. SARS-CoV-2 S protein binds to neuropilin-1 (NRP1) by virtue of a CendR motif which terminates with either an arginine or lysine. Furthermore, a number of different peptide sequences have been reported to bind to the same site in NRP1 including vascular endothelial growth factor A and other viral proteins. To gain a deeper understanding of additional factors besides the C-terminal arginine that may favour high NRP1 binding, several modelled peptides were investigated using triplicate 1 μs molecular dynamics simulations. A C-end histidine failed to exhibit strong NRP1 affinity. Some previously reported factors that increase binding affinity and secure NRP1 receptor activation was observed in the NRP1-peptide complexes studied and such complexes had higher molecular mechanics-generalized Born surface area based free energy of binding. Additionally, the results also highlight the relevance of an exposed arginine at its canonical location as capping it blocked arginine from engaging key residues at the NRP1 receptor site that are indispensable for functional binding; and that the presence of proline reinforces the C-terminal arginine. Given that stable NRP1 binding is crucial for viral uptake, stable interactions should be accounted for in the design of potential drugs and treatment routes to target or disrupt this interface, considering the S1-NRP1 interaction as well as its endogenous VEGF-A ligand that is associated with nociception.

Oligodendrocyte precursor cells (OPCs) are glial cells that differentiate into mature oligodendrocytes (OLs) to generate new myelin sheaths. While OPCs are distributed uniformly throughout the gray and white matter in the developing and adult brain, those in white matter proliferate and differentiate into oligodendrocytes at a greater rate than those in gray matter. There is currently lack of evidence to suggest that OPCs comprise genetically and transcriptionally distinct subtypes. Rather, the emerging view is that they exist in different cell and functional states, depending on their location and age. Contrary to the normal brain, demyelinated lesions in the gray matter of multiple sclerosis brains contain more OPCs and OLs and are remyelinated more robustly than those in white matter. The differences in the dynamic behavior of OL lineage cells are likely to be influenced by their microenvironment. There are regional differences in astrocytes, microglia, the vasculature, and the composition of the extracellular matrix (ECM). We will discuss how the regional differences in these elements surrounding OPCs might shape their phenotypic variability in normal and demyelinated states. [ABSTRACT FROM AUTHOR]

The SARS‐CoV‐2 pandemic has significantly impacted global health. Research on viral mechanisms, highly effective vaccines, and other therapies is in progress. Neuropilins have recently been identified as host cell receptors enabling viral fusion. Here, we provide context to neuropilin's tissue‐specific role in infection and the potential impact of NRP‐based therapeutics. We conclude that the central roles of neuropilins in vascular, neural, and other pathways may render it a less suitable target for treating SARS‐CoV‐2 than agents that target its binding partner, the viral spike protein. [ABSTRACT FROM AUTHOR]

Bone remodeling is the balance between osteoblasts and osteoclasts. Bone diseases such as osteoporosis and osteoarthritis are associated with imbalanced bone remodeling. Skeletal injury leads to limited motor function and pain. Neurophilin was initially identified in axons, and its various ligands and roles in bone remodeling, angiogenesis, neuropathic pain and immune regulation were later discovered. Neurophilin promotes osteoblast mineralization and inhibits osteoclast differentiation and its function. Neuropolin-1 provides channels for immune cell chemotaxis and cytokine diffusion and leads to pain. Neuropolin-1 regulates the proportion of T helper type 17 (Th17) and regulatory T cells (Treg cells), and affects bone immunity. Vascular endothelial growth factors (VEGF) combine with neuropilin and promote angiogenesis. Class 3 semaphorins (Sema3a) compete with VEGF to bind neuropilin, which reduces angiogenesis and rejects sympathetic nerves. This review elaborates on the structure and general physiological functions of neuropilin and summarizes the role of neuropilin and its ligands in bone and cartilage diseases. Finally, treatment strategies and future research directions based on neuropilin are proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

The neuropilins NRP1 and NRP2 are multifunctional glycoproteins that have been implicated in several cancer-related processes including cell survival, migration, and invasion in various tumor types. Here, we examine the role of neuropilins in hepatoblastoma (HB), the most common pediatric liver malignancy. Using a combination of immunohistochemistry, RNA analysis and western blotting, we observed high level expression of NRP1 and NRP2 in 19 of 20 HB specimens and in a majority of human HB cell lines (HUH6 and five cell lines established from patient-derived xenografts) studied but not in normal hepatocytes. Silencing of NRP2 expression in HUH6 and HB-282 HB cells resulted in decreased cell viability, impaired cytoskeleton remodeling, and reduced cell motility, suggesting that NRP2 contributes to the malignant phenotype. We propose that neuropilins warrant further investigation as biomarkers of HB and potential therapeutic targets.

Semaphorins are a group of proteins that have been studied extensively for their critical function in neuronal development. They have been shown to regulate airway development, tumorigenesis, autoimmune diseases, and the adaptive immune response. Notably, emerging literature describes the role of immunoregulatory semaphorins and their receptors, plexins and neuropilins, as modulators of innate immunity and diseases defined by acute injury to the kidneys, abdomen, heart and lungs. In this review we discuss the pathogenic functions of semaphorins in clinical conditions of acute inflammation, including sepsis and acute lung injury, with a focus on regulation of the innate immune response as well as potential future therapeutic targeting.

Semaphorins are a group of proteins that have been studied extensively for their critical function in neuronal development. They have been shown to regulate airway development, tumorigenesis, autoimmune diseases, and the adaptive immune response. Notably, emerging literature describes the role of immunoregulatory semaphorins and their receptors, plexins and neuropilins, as modulators of innate immunity and diseases defined by acute injury to the kidneys, abdomen, heart and lungs. In this review we discuss the pathogenic functions of semaphorins in clinical conditions of acute inflammation, including sepsis and acute lung injury, with a focus on regulation of the innate immune response as well as potential future therapeutic targeting. [ABSTRACT FROM AUTHOR]

Higher grade meningiomas tend to recur. We aimed to evaluate protein levels of vascular endothelial growth factor (VEGF)-A with the VEGF-receptors 1-3 and the co-receptors Neuropilin (NRP)-1 and -2 in WHO grade II and III meningiomas to elucidate the rationale for targeted treatments. We investigated 232 specimens of 147 patients suffering from cranial meningioma, including recurrent tumors. Immunohistochemistry for VEGF-A, VEGFR-1-3, and NRP-1/-2 was performed on tissue micro arrays. We applied a semiquantitative score (staining intensity x frequency). VEGF-A, VEGFR-1-3, and NRP-1 were heterogeneously expressed. NRP-2 was mainly absent. We demonstrated a significant increase of VEGF-A levels on tumor cells in WHO grade III meningiomas (p = 0.0098). We found a positive correlation between expression levels of VEGF-A and VEGFR-1 on tumor cells and vessels (p < 0.0001). In addition, there was a positive correlation of VEGF-A and VEGFR-3 expression on tumor vessels (p = 0.0034). VEGFR-2 expression was positively associated with progression-free survival (p = 0.0340). VEGF-A on tumor cells was negatively correlated with overall survival (p = 0.0084). The VEGF-A-driven system of tumor angiogenesis might still present a suitable target for adjuvant therapy in malignant meningioma disease. However, its role in malignant tumor progression may not be as crucial as expected. The value of comprehensive testing of the ligand and all receptors prior to administration of anti-angiogenic therapy needs to be evaluated in clinical trials. [ABSTRACT FROM AUTHOR]

• Beyond their role in development, Semaphorins are involved in adult neural plasticity, in neural regeneration after injury, and in neurodegenerative diseases. • Semaphorins control cardiovascular development, both physiological and pathological angiogenesis, and bone homeostasis. • Semaphorins regulate innate and adaptive immune responses and are implicated in immunopathologies. • Semaphorins control cancer cell behavior and hijack the function of normal cells in the tumor microenvironment. Cell-cell communication is pivotal to guide embryo development, as well as to maintain adult tissues homeostasis and control immune response. Among extracellular factors responsible for this function, are the Semaphorins, a broad family of around 20 different molecular cues conserved in evolution and widely expressed in all tissues. The signaling cascades initiated by semaphorins depend on a family of conserved receptors, called Plexins, and on several additional molecules found in the receptor complexes. Moreover, multiple intracellular pathways have been described to act downstream of semaphorins, highlighting significant diversity in the signaling cascades controlled by this family. Notably, semaphorin expression is altered in many human diseases, such as immunopathologies, neurodegenerative diseases and cancer. This underscores the importance of semaphorins as regulatory factors in the tissue microenvironment and has prompted growing interest for assessing their potential relevance in medicine. This review article surveys the main contexts in which semaphorins have been found to regulate developing and healthy adult tissues, and the signaling cascades implicated in these functions. Vis a vis, we will highlight the main pathological processes in which semaphorins are thought to have a role thereof. [ABSTRACT FROM AUTHOR]

Background: Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults, with a median survival of approximately 15 months. Semaphorin 3A (Sema3A), known for its axon guidance and antiangiogenic properties, has been implicated in GBM growth. We hypothesized that Sema3A directly inhibits brain tumor stem cell (BTSC) proliferation and drives invasion via Neuropilin 1 (Nrp1) and Plexin A1 (PlxnA1) receptors.Methods: GBM BTSC cell lines were assayed by immunostaining and PCR for levels of Semaphorin 3A (Sema3A) and its receptors Nrp1 and PlxnA1. Quantitative BrdU, cell cycle and propidium iodide labeling assays were performed following exogenous Sema3A treatment. Quantitative functional 2-D and 3-D invasion assays along with shRNA lentiviral knockdown of Nrp1 and PlxnA1 are also shown. In vivo flank studies comparing tumor growth of knockdown versus control BTSCs were performed. Statistics were performed using GraphPad Prism v7.Results: Immunostaining and PCR analysis revealed that BTSCs highly express Sema3A and its receptors Nrp1 and PlxnA1, with expression of Nrp1 in the CD133 positive BTSCs, and absence in differentiated tumor cells. Treatment with exogenous Sema3A in quantitative BrdU, cell cycle, and propidium iodide labeling assays demonstrated that Sema3A significantly inhibited BTSC proliferation without inducing cell death. Quantitative functional 2-D and 3-D invasion assays showed that treatment with Sema3A resulted in increased invasion. Using shRNA lentiviruses, knockdown of either NRP1 or PlxnA1 receptors abrogated Sema3A antiproliferative and pro-invasive effects. Interestingly, loss of the receptors mimicked Sema3A effects, inhibiting BTSC proliferation and driving invasion. Furthermore, in vivo studies comparing tumor growth of knockdown and control infected BTSCs implanted into the flanks of nude mice confirmed the decrease in proliferation with receptor KD.Conclusions: These findings demonstrate the importance of Sema3A signaling in GBM BTSC proliferation and invasion, and its potential as a therapeutic target. [ABSTRACT FROM AUTHOR]

Reelin plays versatile roles in neocortical development. The C-terminal region (CTR) of Reelin is required for the correct formation of the superficial structure of the neocortex; however, the mechanisms by which this position-specific effect occurs remain largely unknown. In this study, we demonstrate that Reelin with an intact CTR binds to neuropilin-1 (Nrp1), a transmembrane protein. Both male and female mice were used. Nrp1 is localized with very-low-density lipoprotein receptor (VLDLR), a canonical Reelin receptor, in the superficial layers of the developing neocortex. It forms a complex with VLDLR, and this interaction is modulated by the alternative splicing of VLDLR. Reelin with an intact CTR binds more strongly to the VLDLR/Nrp1 complex than to VLDLR alone. Knockdown of Nrp1 in neurons leads to the accumulation of Dab1 protein. Since the degradation of Dab1 is induced by Reelin signaling, it is suggested that Nrp1 augments Reelin signaling. The interaction between Reelin and Nrp1 is required for normal dendritic development in superficial-layer neurons. All of these characteristics of Reelin are abrogated by proteolytic processing of the six C-terminal amino acid residues of Reelin (0.17% of the whole protein). Therefore, Nrp1 is a coreceptor molecule for Reelin and, together with the proteolytic processing of Reelin, can account for context-specific Reelin function in brain development. [ABSTRACT FROM AUTHOR]

Objective: Neuropilin-2 (NRP2) is a coreceptor of vascular endothelial growth factor-C/D (VEGF-C/D) and plays the important role in the development of lymphatic endothelial cells, as well as neuronal development. NRP2 is known to affect aggressiveness by increasing expression in various human cancers, but the role of NRP2 in thyroid cancer is not fully understood. The purpose of this study was to investigate the NRP2 expression and its role in regulating the tumor aggressiveness in the papillary thyroid carcinoma (PTC).Methods: The NRP2 expression and its clinicopathologic correlation to PTC was determined using the data from the 262 PTC patients at a tertiary referral medical center and The Cancer Genome Atlas (TCGA) database. The potential role of NRP2 in modulating tumor growth, invasion, and metastasis in PTC was examined by using small interfering RNA (siRNA)-mediated knockdown of NRP2.Results: High expression of NRP2 was significantly associated with capsular invasion, lymphovascular invasion, lymph node metastasis, 5 or more metastatic lymph nodes, and recurrence in PTC patients. In TCGA data, the higher NRP2 expression group was significantly associated with extrathyroid extension, lymph node metastasis, and BRAFV600E mutation. The siRNA mediated knockdown of NRP2 in the PTC cells reduced the cell proliferation, migration and invasion. We also have confirmed that NRP2 knockdown suppressed epithelial-mesenchymal transition (EMT) by regulating AKT and ERK phosphorylation signaling pathways.Conclusion: Our results suggest that NRP2 regulates tumor progression in PTC and may act as a predictive factor for aggressiveness of PTC. [ABSTRACT FROM AUTHOR]

Herpesviruses are ubiquitous human pathogens that cause a wide range of health complications. Currently, there is an incomplete understanding of cellular factors that contribute to herpesvirus infection. Here, we report an antiviral necroptosis-based genetic screen to identify novel host cell factors required for infection with the β-herpesvirus murine cytomegalovirus (MCMV). Our genomewide CRISPR-based screen harnessed the capacity of herpesvirus mutants that trigger antiviral necroptotic cell death upon early viral gene expression. Vascular endothelial growth factor (VEGF) and semaphorin-binding receptor Neuropilin-1 (Nrp-1) emerge as crucial determinants of MCMV infection. We find that elimination of Nrp-1 impairs early viral gene expression and reduces infection rates in endothelial cells, fibroblasts, and macrophages. Furthermore, preincubation of virus with soluble Nrp-1 dramatically inhibits infection by reducing virus attachment. Thus, Nrp-1 is a key determinant of the initial phase of MCMV infection. [ABSTRACT FROM AUTHOR]

Background: VEGFR2 (vascular endothelial growth factor receptor 2) is the major pro-angiogenic receptor in endothelial cells. Compared to other members of the receptor tyrosine kinase family, we know relatively few VEGFR2 signaling partners. Our objective was to use mass spectrometry-based proteomics to identify novel binding partners of activated VEGFR2. Methods: We created an endothelial cell line stably expressing GFP-tagged VEGFR2 and isolated activated receptor complexes. Analysis by mass spectrometry identified raftlin as a novel binding partner of VEGFR2. Results: We found that raftlin is recruited to the activated VEGFR2 complex via the co-receptor Nrp1 (neuropilin-1). We show that raftlin regulates the surface levels of Nrp1 in endothelial cells, controlling the availability of Nrp1 for VEGFR2 interaction. Raftlin stabilizes active VEGFR2 at the cell surface by inhibiting endocytosis of the activated receptor. Raftlin also promotes recycling of internalized VEGFR2 to the cell surface. Raftlin alters the signaling outcomes of VEGFR2 activation, inhibiting the activation of p38 and FAK (focal adhesion kinases) specifically. Both pathways are linked to cell migration in endothelial cells, and raftlin inhibits endothelial cell migration in response to VEGF. Conclusion: Nrp1 is an important co-receptor for VEGFR2; however, its functions are still only partially understood. We show that raftlin works with Nrp1 in endothelial cells to control intracellular trafficking of the activated VEGFR2. This modulates the response to VEGF and controls endothelial cell migration. [ABSTRACT FROM AUTHOR]

Renal cell carcinoma (RCC) treatment has improved in the last decade with the introduction of drugs targeting tumor angiogenesis. However, the 5‐year survival of metastatic disease is still only 10–15%. Here, we explored the prognostic significance of compartment‐specific expression of Neuropilin 1 (NRP1), a co‐receptor for vascular endothelial growth factor (VEGF). NRP1 expression was analyzed in RCC tumor vessels, in perivascular tumor cells, and generally in the tumor cell compartment. Moreover, complex formation between NRP1 and the main VEGF receptor, VEGFR2, was determined. Two RCC tissue microarrays were used; a discovery cohort consisting of 64 patients and a validation cohort of 314 patients. VEGFR2/NRP1 complex formation in cis (on the same cell) and trans (between cells) configurations was determined by in situ proximity ligation assay (PLA), and NRP1 protein expression in three compartments (endothelial cells, perivascular tumor cells, and general tumor cell expression) was determined by immunofluorescent staining. Expression of NRP1 in perivascular tumor cells was explored as a marker for RCC survival in the two RCC cohorts. Results were further validated using a publicly available gene expression dataset of clear cell RCC (ccRCC). We found that VEGFR2/NRP1 trans complexes were detected in 75% of the patient samples. The presence of trans VEGFR2/NRP1 complexes or perivascular NRP1 expression was associated with a reduced tumor vessel density and size. When exploring NRP1 as a biomarker for RCC prognosis, perivascular NRP1 and general tumor cell NRP1 protein expression correlated with improved survival in the two independent cohorts, and significant results were obtained also at the mRNA level using the publicly available ccRCC gene expression dataset. Only perivascular NRP1 expression remained significant in multivariable analysis. Our work shows that perivascular NRP1 expression is an independent marker of improved survival in RCC patients, and reduces tumor vascularization by forming complexes in trans with VEGFR2 in the tumor endothelium. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Pancreatic cancer, one of the most fatal types of human cancers, includes several non-epithelial and stromal components, such as activated fibroblasts, vascular cells, neural cells and immune cells, that are involved in different cancers. Vascular endothelial cell growth factor 165 receptors 1 [neuropilin-1 (NRP-1)] and 2 (NRP-2) play a role in the biological behaviors of pancreatic cancer and may appear as potential therapeutic targets. The NRP family of proteins serve as co-receptors for vascular endothelial growth factor, transforming growth factor β, hepatocyte growth factor, fibroblast growth factor, semaphorin 3, epidermal growth factor, insulin-like growth factor and platelet-derived growth factor. Investigations of mechanisms that involve the NRP family of proteins may help develop novel approaches for overcoming therapy resistance in pancreatic cancer. The present review aimed to provide an in-depth exploration of the multifaceted roles of the NRP family of proteins in pancreatic cancer, including recent findings from single-cell analysis conducted within the context of pancreatic adenocarcinoma, which revealed the intricate involvement of NRP proteins at the cellular level. Through these efforts, the present study endeavored to further reveal their relationships with different biological processes and their potential as therapeutic targets in various treatment modalities, offering novel perspectives and directions for the treatment of pancreatic cancer. [ABSTRACT FROM AUTHOR]

Obesity is a leading cause of cardiovascular diseases and cancer. Body mass is regulated by the balance between energy uptake and energy expenditure. The etiology of obesity is determined by multiple factors including genetics, nutrient absorption, and inflammation. Lymphatic vasculature is starting to be appreciated as a critical modulator of metabolism and obesity. The primary function of lymphatic vasculature is to maintain interstitial fluid homeostasis. Lymphatic vessels absorb fluids that extravasate from blood vessels and return them to blood circulation. In addition, lymphatic vessels absorb digested lipids from the intestine and regulate inflammation. Hence, lymphatic vessels could be an exciting target for treating obesity. In this article, we will review our current understanding regarding the relationship between lymphatic vasculature and obesity, and highlight some open questions.

While semaphorins were initially identified as axonal guidance cues for wiring the neural network, it was then recognized their wide relevance in tissue development and homeostasis. Notably, semaphorin activities were also extensively studied in many types of solid tumors; however, their relevance in hematological malignancies is far from understood. In this mini-review, we surveyed the current knowledge about semaphorins and their receptors in leukemias, lymphomas, and multiple myeloma. Noteworthy, current data support a promoting role for Semaphorin 4D and Neuropilin-1 in these tumors, while Semaphorin 3A seems to consistently act as oncosuppressor in leukemias and multiple myeloma. The expression levels and functional activities of SEMA3B, SEMA3F, and Neuropilin-2 have furthermore been investigated in leukemias and lymphoma cells. Herein, we reviewed the state of the art and highlighted some of the open questions to be addressed in the field.