Neuropilin-2, a novel member of the neuropilin family, is a high affinity receptor for the semaphorins Sema E and Sema IV but not Sema III

Semaphorin Receptors Antagonize Wnt Signaling Through Beta-Catenin Degradation

Precise control of morphogen signaling levels is essential for proper development. An outstanding question is: what mechanisms ensure proper morphogen activity and correct cellular responses? Previous work has identified Semaphorin (SEMA) receptors, Neuropilins (NRPs) and Plexins (PLXNs), as positive regulators of the Hedgehog (HH) signaling pathway. Here, we provide evidence that NRPs and PLXNs antagonize Wnt signaling in both fibroblasts and epithelial cells. Further, Nrp1/2 deletion in fibroblasts results in elevated baseline Wnt pathway activity and increased maximal responses to Wnt stimulation. Notably, and in contrast to HH signaling, SEMA receptor-mediated Wnt antagonism is independent of primary cilia. Mechanistically, PLXNs and NRPs act downstream of Dishevelled (DVL) to destabilize β-catenin (CTNNB1) in a proteosome-dependent manner. Further, NRPs, but not PLXNs, act in a GSK3β/CK1-dependent fashion to antagonize Wnt signaling, suggesting distinct repressive mechanisms for these SEMA receptors. Overall, this study identifies SEMA receptors as novel Wnt pathway antagonists that may also play larger roles integrating signals from multiple inputs.

Neuron-specific RNA-sequencing reveals different responses in peripheral neurons after nerve injury

Peripheral neurons are heterogeneous and functionally diverse, but all share the capability to switch to a pro-regenerative state after nerve injury. Despite the assumption that the injury response is similar among neuronal subtypes, functional recovery may differ. Understanding the distinct intrinsic regenerative properties between neurons may help to improve the quality of regeneration, prioritizing the growth of axon subpopulations to their targets. Here, we present a comparative analysis of regeneration across four key peripheral neuron populations: motoneurons, proprioceptors, cutaneous mechanoreceptors, and nociceptors. Using Cre/Ai9 mice that allow fluorescent labeling of neuronal subtypes, we found that nociceptors showed the greater regeneration after a sciatic crush, followed by motoneurons, mechanoreceptors, and, finally, proprioceptors. By breeding these Cre mice with Ribotag mice, we isolated specific translatomes and defined the regenerative response of these neuronal subtypes after axotomy. Only 20% of the regulated genes were common, revealing a diverse response to injury among neurons, which was also supported by the differential influence of neurotrophins among neuron subtypes. Among differentially regulated genes, we proposed MED12 as a specific regulator of the regeneration of proprioceptors. Altogether, we demonstrate that the intrinsic regenerative capacity differs between peripheral neuron subtypes, opening the door to selectively modulate these responses.

Precision nutrition to reset virus-induced human metabolic reprogramming and dysregulation (HMRD) in long-COVID

SARS-CoV-2, the etiological agent of COVID-19, is devoid of any metabolic capacity; therefore, it is critical for the viral pathogen to hijack host cellular metabolic machinery for its replication and propagation. This single-stranded RNA virus with a 29.9 kb genome encodes 14 open reading frames (ORFs) and initiates a plethora of virus-host protein-protein interactions in the human body. These extensive viral protein interactions with host-specific cellular targets could trigger severe human metabolic reprogramming/dysregulation (HMRD), a rewiring of sugar-, amino acid-, lipid-, and nucleotide-metabolism(s), as well as altered or impaired bioenergetics, immune dysfunction, and redox imbalance in the body. In the infectious process, the viral pathogen hijacks two major human receptors, angiotensin-converting enzyme (ACE)-2 and/or neuropilin (NRP)-1, for initial adhesion to cell surface; then utilizes two major host proteases, TMPRSS2 and/or furin, to gain cellular entry; and finally employs an endosomal enzyme, cathepsin L (CTSL) for fusogenic release of its viral genome. The virus-induced HMRD results in 5 possible infectious outcomes: asymptomatic, mild, moderate, severe to fatal episodes; while the symptomatic acute COVID-19 condition could manifest into 3 clinical phases: (i) hypoxia and hypoxemia (Warburg effect), (ii) hyperferritinemia ('cytokine storm'), and (iii) thrombocytosis (coagulopathy). The mean incubation period for COVID-19 onset was estimated to be 5.1 days, and most cases develop symptoms after 14 days. The mean viral clearance times were 24, 30, and 39 days for acute, severe, and ICU-admitted COVID-19 patients, respectively. However, about 25-70% of virus-free COVID-19 survivors continue to sustain virus-induced HMRD and exhibit a wide range of symptoms that are persistent, exacerbated, or new 'onset' clinical incidents, collectively termed as post-acute sequelae of COVID-19 (PASC) or long COVID. PASC patients experience several debilitating clinical condition(s) with >200 different and overlapping symptoms that may last for weeks to months. Chronic PASC is a cumulative outcome of at least 10 different HMRD-related pathophysiological mechanisms involving both virus-derived virulence factors and a multitude of innate host responses. Based on HMRD and virus-free clinical impairments of different human organs/systems, PASC patients can be categorized into 4 different clusters or sub-phenotypes: sub-phenotype-1 (33.8%) with cardiac and renal manifestations; sub-phenotype-2 (32.8%) with respiratory, sleep and anxiety disorders; sub-phenotype-3 (23.4%) with skeleto-muscular and nervous disorders; and sub-phenotype-4 (10.1%) with digestive and pulmonary dysfunctions. This narrative review elucidates the effects of viral hijack on host cellular machinery during SARS-CoV-2 infection, ensuing detrimental effect(s) of virus-induced HMRD on human metabolism, consequential symptomatic clinical implications, and damage to multiple organ systems; as well as chronic pathophysiological sequelae in virus-free PASC patients. We have also provided a few evidence-based, human randomized controlled trial (RCT)-tested, precision nutrients to reset HMRD for health recovery of PASC patients.

Revealing neuropilin expression patterns in pancreatic cancer: From single‑cell to therapeutic opportunities (Review)

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.

Orchestrating Resilience: How Neuropilin-2 and Macrophages Contribute to Cardiothoracic Disease

Immunity has evolved to balance the destructive nature of inflammation with wound healing to overcome trauma, infection, environmental insults, and rogue malignant cells. The inflammatory response is marked by overlapping phases of initiation, resolution, and post-resolution remodeling. However, the disruption of these events can lead to prolonged tissue damage and organ dysfunction, resulting long-term disease states. Macrophages are the archetypic phagocytes present within all tissues and are important contributors to these processes. Pleiotropic and highly plastic in their responses, macrophages support tissue homeostasis, repair, and regeneration, all while balancing immunologic self-tolerance with the clearance of noxious stimuli, pathogens, and malignant threats. Neuropilin-2 (Nrp2), a promiscuous co-receptor for growth factors, semaphorins, and integrins, has increasingly been recognized for its unique role in tissue homeostasis and immune regulation. Notably, recent studies have begun to elucidate the role of Nrp2 in both non-hematopoietic cells and macrophages with cardiothoracic disease. Herein, we describe the unique role of Nrp2 in diseases of the heart and lung, with an emphasis on Nrp2 in macrophages, and explore the potential to target Nrp2 as a therapeutic intervention.

New Promising Routes in Peptic Ulcers: Toll-like Receptors and Semaphorins

Peptic ulcers (PU) are one of the commonest yet problematic diseases found to be existing in the majority of the population. Today, drugs from a wide range of therapeutic classes are available for the management of the disease. Still, the complications of the condition are difficult to tackle and the side effect profile is quite a concern. The literature indicates that Toll-like receptors (TLRs) and Semaphorins (SEMAs) have been under study for their various pharmacological actions over the past few decades. Both these signalling pathways are found to regulate immunological and inflammatory responses. Moreover, receptors and signalling molecules from the family of TLRs and SEMAs are found to have bacterial recognition and antibacterial properties which are essential in eradicating Helicobacter pylori (H. pylori), one of the major causative agents of PU. Our understanding of SEMAs, a class of proteins involved in cell signalling, is relatively less developed compared to TLRs, another class of proteins involved in the immune response. SEMAs and TLRs play different roles in biological processes, with SEMAs primarily involved in guiding cell migration and axon guidance during development, while TLRs are responsible for recognizing pathogens and initiating an immune response. Here, in this review, we will discuss in detail the signalling cascade of TLRs and SEMAs and thereby understand its association with PU for future therapeutic targeting. The review also aims at providing an overview of the study that has been into exploring the role of these signalling pathways in the management of PU.

Is neuropilin-1 the neuroimmune initiator of multi-system hyperinflammation in COVID-19?

A major immunopathological feature of Coronavirus disease-2019 (COVID-19) is excessive inflammation in the form of "cytokine storm". The storm is characterized by injurious levels of cytokines which form a complicated network damaging different organs, including the lungs and the brain. The main starter of "cytokine network" hyperactivation in COVID-19 has not been discovered yet. Neuropilins (NRPs) are transmembrane proteins that act as neuronal guidance and angiogenesis modulators. The crucial function of NRPs in forming the nervous and vascular systems has been well-studied. NRP1 and NRP2 are the two identified homologs of NRP. NRP1 has been shown as a viral entry pathway for SARS-CoV2, which facilitates neuroinvasion by the virus within the central or peripheral nervous systems. These molecules directly interact with various COVID-19-related molecules, such as specific regions of the spike protein (major immune element of SARS-CoV2), vascular endothelial growth factor (VEGF) receptors, VEGFR1/2, and ANGPTL4 (regulator of vessel permeability and integrity). NRPs mainly play a role in hyperinflammatory injury of the CNS and lungs, and also the liver, kidney, pancreas, and heart in COVID-19 patients. New findings have suggested NRPs good candidates for pharmacotherapy of COVID-19. However, therapeutic targeting of NRP1 in COVID-19 is still in the preclinical phase. This review presents the implications of NRP1 in multi-organ inflammation-induced injury by SARS-CoV2 and provides insights for NRP1-targeting treatments for COVID-19 patients.

Therapeutic blocking of VEGF binding to neuropilin-2 diminishes PD-L1 expression to activate antitumor immunity in prostate cancer

Prostate cancers are largely unresponsive to immune checkpoint inhibitors (ICIs), and there is strong evidence that programmed death-ligand 1 (PD-L1) expression itself must be inhibited to activate antitumor immunity. Here, we report that neuropilin-2 (NRP2), which functions as a vascular endothelial growth factor (VEGF) receptor on tumor cells, is an attractive target to activate antitumor immunity in prostate cancer because VEGF-NRP2 signaling sustains PD-L1 expression. NRP2 depletion increased T cell activation in vitro. In a syngeneic model of prostate cancer that is resistant to ICI, inhibition of the binding of VEGF to NRP2 using a mouse-specific anti-NRP2 monoclonal antibody (mAb) resulted in necrosis and tumor regression compared with both an anti-PD-L1 mAb and control immunoglobulin G. This therapy also decreased tumor PD-L1 expression and increased immune cell infiltration. We observed that the NRP2, VEGFA, and VEGFC genes are amplified in metastatic castration-resistant and neuroendocrine prostate cancer. We also found that individuals with NRP2^High PD-L1^High metastatic tumors had lower androgen receptor expression and higher neuroendocrine prostate cancer scores than other individuals with prostate cancer. In organoids derived from patients with neuroendocrine prostate cancer, therapeutic inhibition of VEGF binding to NRP2 using a high-affinity humanized mAb suitable for clinical use also diminished PD-L1 expression and caused a substantial increase in immune-mediated tumor cell killing, consistent with the animal studies. These findings provide justification for the initiation of clinical trials using this function-blocking NRP2 mAb in prostate cancer, especially for patients with aggressive disease.

Mutating novel interaction sites in NRP1 reduces SARS-CoV-2 spike protein internalization

The global pandemic of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has become a severe global health problem because of its rapid spread. Both Ace2 and NRP1 provide initial viral binding sites for SARS-CoV-2. Here, we show that cysteine residues located in the vestigial plasminogen-apple-nematode (PAN) domain of NRP1 are necessary for SARS-CoV-2 spike protein internalization. Mutating novel cysteine residues in the PAN altered NRP1 stability and downstream activation of extracellular signal-regulated kinase (ERK) signaling pathway and impaired its interaction with the spike protein. This resulted in a significant reduction in spike protein abundance in Vero-E6 cells for the original, alpha, and delta SARS-CoV-2 variants even in the presence of the Ace2. Moreover, mutating these cysteine residues in NRP1 significantly lowered its association with Plexin-A1. As the spike protein is a critical component for targeted therapy, our biochemical study may represent a distinct mechanism to develop a path for future therapeutic discovery.

Quercetin protects endothelial function from inflammation induced by localized disturbed flow by inhibiting NRP2 -VEGFC complex

Atherosclerosis is a focal chronic inflammatory disease, the initial pathogenic event of which is endothelial dysfunction, and disturbed flow (DF) is the primary and vital factor underlying endothelial dysfunction. The present research aims to elucidate the mechanism underlying the regulation of Neuropilin (NRP)2 under DF in endothelial cells (ECs) in an inflammatory state. We observed that NRP2 expression was significantly upregulated in DF-stimulated human umbilical vein endothelial cells (HUVECs). Knockdown of NRP2 in HUVECs significantly ameliorated cell inflammation induced by DF. In addition, quercetin inhibited NRP2 expression as well as endothelial inflammation. Animal experiments suggested that NRP2 knockdown or intraperitoneal injection of quercetin affected the expression of inflammation-related genes. Moreover, the upstream transcription factor GATA2 was found to regulate NRP2 transcription by binding to the -1100 to +100 bp region of the NRP2 promoter. Further studies showed that quercetin inhibited NRP2-VEGFC complex formation induced by disturbed flow, although did not inhibit GATA2 expression. These findings suggest that NRP2 plays an important role in promoting inflammation. Quercetin antagonizes atherosclerosis by inhibiting NRP2 and the formation of NRP2-VEGFC complex by inhibiting the inflammatory effects induced by disordered flow.

Advances in SEMA3F regulation of clinically high-incidence cancers

Cancer has become a leading cause of morbidity and mortality in recent years. Its high prevalence has had a severe impact on society. Researchers have achieved fruitful results in the causative factors, pathogenesis, treatment strategies, and cancer prevention. Semaphorin 3F (SEMA3F), a member of the signaling family, was initially reported in the literature to inhibit the growth, invasion, and metastasis of cancer cells in lung cancer. Later studies showed it has cancer-inhibiting effects in malignant tumors such as breast, colorectal, ovarian, oral squamous cell carcinoma, melanoma, and head and neck squamous carcinoma. In contrast, recent studies have reported that SEMA3F is expressed more in hepatocellular carcinoma than in normal tissue and promotes metastasis of hepatocellular carcinoma. We chose lung, breast, colorectal, and hepatocellular carcinomas with high clinical prevalence to review the roles and molecular mechanisms of SEMA3F in these four carcinomas. We concluded with an outlook on clinical interventions for patients targeting SEMA3F.

A balance of noncanonical Semaphorin signaling from the cerebrospinal fluid regulates apical cell dynamics during corticogenesis

During corticogenesis, dynamic regulation of apical adhesion is fundamental to generate correct numbers and cell identities. While radial glial cells (RGCs) maintain basal and apical anchors, basal progenitors and neurons detach and settle at distal positions from the apical border. Whether diffusible signals delivered from the cerebrospinal fluid (CSF) contribute to the regulation of apical adhesion dynamics remains fully unknown. Secreted class 3 Semaphorins (Semas) trigger cell responses via Plexin-Neuropilin (Nrp) membrane receptor complexes. Here, we report that unconventional Sema3-Nrp preformed complexes are delivered by the CSF from sources including the choroid plexus to Plexin-expressing RGCs via their apical endfeet. Through analysis of mutant mouse models and various ex vivo assays mimicking ventricular delivery to RGCs, we found that two different complexes, Sema3B/Nrp2 and Sema3F/Nrp1, exert dual effects on apical endfeet dynamics, nuclei positioning, and RGC progeny. This reveals unexpected balance of CSF-delivered guidance molecules during cortical development.

Neuropilin 2 Is a Novel Regulator of Distal Colon Contractility

Appropriate coordination of smooth muscle contraction and relaxation is essential for normal colonic motility. The impact of perturbed motility ranges from moderate, in conditions such as colitis, to potentially fatal in the case of pseudo-obstruction. The mechanisms underlying aberrant motility and the extent to which they can be targeted pharmacologically are incompletely understood. This study identified colonic smooth muscle as a major site of expression of neuropilin 2 (Nrp2) in mice and humans. Mice with inducible smooth muscle-specific knockout of Nrp2 had an increase in evoked contraction of colonic rings in response to carbachol at 1 and 4 weeks following initiation of deletion. KCl-induced contractions were also increased at 4 weeks. Colonic motility was similarly enhanced, as evidenced by faster bead expulsion in Nrp2-deleted mice versus Nrp2-intact controls. In length-tension analysis of the distal colon, passive tension was similar in Nrp2-deficient and Nrp2-intact mice, but at low strains, active stiffness was greater in Nrp2-deficient animals. Consistent with the findings in conditional Nrp2 mice, Nrp2-null mice showed increased contractility in response to carbachol and KCl. Evaluation of selected proteins implicated in smooth muscle contraction revealed no significant differences in the level of α-smooth muscle actin, myosin light chain, calponin, or RhoA. Together, these findings identify Nrp2 as a novel regulator of colonic contractility that may be targetable in conditions characterized by dysmotility.

Spatial regulation of amacrine cell genesis by Semaphorin 3f

PURPOSE

The axonal projections of retinal ganglion cells (RGCs) of the eye are topographically organized so that spatial information from visual images is preserved. This retinotopic organization is established during development by secreted morphogens that pattern domains of transcription factor expression within naso-temporal and dorso-ventral quadrants of the embryonic eye. Poorly understood are the downstream signaling molecules that generate the topographically organized retinal cells and circuits. The secreted signaling molecule Semaphorin 3fa (Sema3fa) belongs to the Sema family of molecules that provide positional information to developing cells. Here, we test a role for Sema3fa in cell genesis of the temporal zebrafish retina.

METHODS

We compare retinal cell genesis in wild type and sema3fa CRISPR zebrafish mutants by in situ hybridization and immunohistochemistry.

RESULTS

We find that mRNAs for sema3fa and known receptors, neuropilin2b (nrp2b) and plexina1a (plxna1a), are expressed by progenitors of the temporal, but not nasal zebrafish embryonic retina. In the sema3fa^ca304/ca304 embryo, initially the domains of expression for atoh7 and neurod4, transcription factors necessary for the specification of RGCs and amacrine cells, respectively, are disrupted. Yet, post-embryonically only amacrine cells of the temporal retina are reduced in numbers, with both GABAergic and glycinergic subtypes affected.

CONCLUSIONS

These data suggest that Sema3fa acts early on embryonic temporal progenitors to control in a spatially-dependent manner the production of amacrine cells, possibly to allow the establishment of neural circuits with domain-specific functions. We propose that spatially restricted extrinsic signals in the neural retina control cell genesis in a domain-dependent manner.

VEGFR endocytosis: Implications for angiogenesis

The binding of vascular endothelial growth factor (VEGF) superfamily to VEGF receptor tyrosine kinases (VEGFRs) and co-receptors regulates vasculogenesis, angiogenesis and lymphangiogenesis. A recurring theme is that dysfunction in VEGF signaling promotes pathological angiogenesis, an important feature of cancer and pro-inflammatory disease states. Endocytosis of basal (resting) or activated VEGFRs facilitates signal attenuation and endothelial quiescence. However, increasing evidence suggest that activated VEGFRs can continue to signal from intracellular compartments such as endosomes. In this chapter, we focus on the evolving link between VEGFR endocytosis, signaling and turnover and the implications for angiogenesis. There is much interest in how such understanding of VEGFR dynamics can be harnessed therapeutically for a wide range of human disease states.

Role of Neuropilin-2-mediated signaling axis in cancer progression and therapy resistance

Neuropilins (NRPs) are transmembrane proteins involved in vascular and nervous system development by regulating angiogenesis and axon guidance cues. Several published reports have established their role in tumorigenesis. NRPs are detectable in tumor cells of several cancer types and participate in cancer progression. NRP2 is also expressed in endothelial and immune cells in the tumor microenvironment and promotes functions such as lymphangiogenesis and immune suppression important for cancer progression. In this review, we have taken a comprehensive approach to discussing various aspects of NRP2-signaling in cancer, including its regulation, functional significance in cancer progression, and how we could utilize our current knowledge to advance the studies and target NRP2 to develop effective cancer therapies.

Therapeutic potential of traditional Chinese medicine for vascular endothelial growth factor

Vascular endothelial growth factor (VEGF) is the main regulator of physiological angiogenesis during embryonic development, bone growth, and reproductive function, and it also participates in a series of pathological changes. Traditional Chinese medicine (TCM), with a history of more than 2000 years, has been widely used in clinical practice, while the exploration of its mechanisms has only begun. This review summarizes the research of recent years on the influence of TCM on VEGF. It is found that many Chinese medicines and recipes have a regulatory effect on VEGF, indicating that Chinese medicine has broad prospects as a complementary and alternative therapy, providing new treatment ideas for clinical applications and the theoretical basis for research on the mechanisms of TCM.

NRP2 promotes atherosclerosis by upregulating PARP1 expression and enhancing low shear stress-induced endothelial cell apoptosis

Atherosclerosis-related cardiovascular diseases are leading causes of mortality worldwide, characterized by the development of endothelial cell dysfunction, increased oxidized low-density lipoprotein uptake by macrophages, and the ensuing formation of atherosclerotic plaque. Local blood flow patterns cause uneven atherosclerotic lesion distribution, and endothelial dysfunction caused by disturbed flow is an early step in the development of atherosclerosis. The present research aims to elucidate the mechanism underlying the regulation of Neuropilin 2 (NRP2) under low shear stress (LSS) in the atheroprone phenotype of endothelial cells. We observed that NRP2 expression was significantly upregulated in LSS-stimulated human umbilical vein endothelial cells (HUVECs) and in mouse aortic endothelial cells. Knockdown of NRP2 in HUVECs significantly ameliorated cell apoptosis induced by LSS. Conversely, overexpression of NRP2 had the opposite effect on HUVEC apoptosis. Animal experiments suggest that NRP2 knockdown markedly mitigated the development of atherosclerosis in Apoe^-/- mice. Mechanistically, NRP2 knockdown and overexpression regulated PARP1 protein expression in the condition of LSS, which in turn affected the expression of apoptosis-related genes. Moreover, the upstream transcription factor GATA2 was found to regulate NRP2 expression in the progression of atherosclerosis. These findings suggest that NRP2 plays an essential proatherosclerotic role through the regulation of cell apoptosis, and the results reveal that NRP2 is a promising therapeutic target for the treatment of atherosclerotic disorders.

Loss of Neuropilin2a/b or Sema3fa alters olfactory sensory axon dynamics and protoglomerular targeting

BACKGROUND

Olfactory Sensory Neuron (OSN) axons project from the zebrafish olfactory epithelium to reproducible intermediate target locations in the olfactory bulb called protoglomeruli at early stages in development. Two classes of OSNs expressing either OMP or TRPC2 exclusively target distinct, complementary protoglomeruli. Using RNAseq, we identified axon guidance receptors nrp2a and nrp2b, and their ligand sema3fa, as potential guidance factors that are differentially expressed between these two classes of OSNs.

METHODS

To investigate their role in OSN axon guidance, we assessed the protoglomerular targeting fidelity of OSNs labeled by OMP:RFP and TRPC2:Venus transgenes in nrp2a, nrp2b, or sema3fa mutants. We used double mutant and genetic interaction experiments to interrogate the relationship between the three genes. We used live time-lapse imaging to compare the dynamic behaviors of OSN growth cones during protoglomerular targeting in heterozygous and mutant larvae.

RESULTS

The fidelity of protoglomerular targeting of TRPC2-class OSNs is degraded in nrp2a, nrp2b, or sema3fa mutants, as axons misproject into OMP-specific protoglomeruli and other ectopic locations in the bulb. These misprojections are further enhanced in nrp2a;nrp2b double mutants suggesting that nrp2s work at least partially in parallel in the same guidance process. Results from genetic interaction experiments are consistent with sema3fa acting in the same biological pathway as both nrp2a and nrp2b. Live time-lapse imaging was used to examine the dynamic behavior of TRPC2-class growth cones in nrp2a mutants compared to heterozygous siblings. Some TRPC2-class growth cones ectopically enter the dorsal-medial region of the bulb in both groups, but in fully mutant embryos, they are less likely to correct the error through retraction. The same result was observed when TRPC2-class growth cone behavior was compared between sema3fa heterozygous and sema3fa mutant larvae.

CONCLUSIONS

Our results suggest that nrp2a and nrp2b expressed in TRPC2-class OSNs help prevent their mixing with axon projections in OMP-specific protoglomeruli, and further, that sema3fa helps to exclude TRPC2-class axons by repulsion from the dorsal-medial bulb.

Genetics of menstrual migraine and their association with female hormonal factors

Perimenopause is linked to increased migraine (Mg), especially menstrual Mg (MMg), influenced by hormonal changes. Compared to nonmenstrual attacks, menstrual attacks are more disabling and less responsive to treatment. Women with perimenstrual estrogen withdrawal have been linked to Mg during menstruation, whereas Mg during perimenopause has been linked to unpredictable fluctuations in estrogen levels. It has been widely established that female sex hormones play a role in Mg, but how it occurs remains unclear. This narrative review was identified using Medline and PubMed searches between 1946 and 2021. Search terms included “headache,” “migraine,” “menstrual migraine,” “menstruation,” “menopause,” “perimenopause,” “estrogen,” and “progesterone.” This article focuses on the candidate genes and female hormones that play a role in MMg. More study is necessary to understand better the environmental components that play a critical role in disease development. Currently, there is insufficient clinical evidence to support the function of menstrual Mg. The specific research facts examined MMg unique candidate genes and female hormonal factors that support their association and found MMg etiologic processes for generating an early diagnostic marker.

Regulation of axon pruning of mossy fiber projection in hippocampus by CRMP2 and CRMP4

Axon pruning facilitates the removal of ectopic and misguided axons and plays an important role in neural circuit formation during brain development. Sema3F and its receptor neuropilin-2 (Nrp2) have been shown to be involved in the stereotyped pruning of the infrapyramidal bundle (IPB) of mossy fibers of the dentate gyrus (DG) in the developing hippocampus. Collapsin response mediator proteins (CRMPs) were originally identified as an intracellular mediator of semaphorin signaling, and the defective pruning of IPB was recently reported in CRMP2-/- and CRMP3-/- mice. CRMP1 and CRMP4 have high homology to CRMP2 and CRMP3, and their expression in the developing mouse brain overlaps; however, their role in IPB pruning has not yet been examined. In this study, we report that CRMP4, but not CRMP1, is involved in IPB pruning during neural circuit formation in the hippocampus. Our genetic interaction analyses indicated that CRMP2 and CRMP4 have distinct functions and that CRMP2 mediates IPB pruning via Nrp2. We also observed the altered synaptic terminals of mossy fibers in CRMP2 and CRMP4 mutant mice. These results suggest that CRMP family members have a distinct function in the axon pruning and targeting of mossy fibers of the hippocampal DG in the developing mouse brain.

Lentiviral Mediated Expression of Soluble Neuropilin 1 Inhibits Semaphorin 3A-mediated Collapse Activity in Vitro

Introduction

Semaphorin 3A (Sema 3A) is a secreted protein, which plays an integral part in developing the nervous system. It has collapse activity on the growth cone of dorsal root ganglia. After the development of the nervous system, Sema 3A expression decreases. Neuropilin 1 is a membrane receptor of Sema 3A. When semaphorin binds to neuropilin 1, the recruitment of oligodendrocyte precursor cells to the demyelinated site decreases. In Multiple Sclerosis (MS), Sema 3A expression increases and inhibits oligodendrocyte precursor cell differentiation. Therefore, the remyelination of axons gets impaired. We hypothesized that the function of Sema 3A could be inhibited by neutralizing its binding to membrane NRP1.

Methods

we cloned a soluble form of mouse Neuropilin 1 (msNRP1) in a lentiviral vector and expressed the recombinant protein in HEK293T cells. Then, the conditioned medium of the transduced cells was used to evaluate the effects of the msNRP1 on the inhibition of Sema 3A-induced growth cone collapse activity. Dorsal root ganglion explants of timed pregnant (E13) mice were prepared. Then, the growth cone collapse activity of Sema 3A was assessed in the presence and absence of msNRP1-containing conditioned media of transduced and non-transduced HEK293T cells. Comparisons between groups were performed by 1-way ANOVA and post hoc Tukey tests.

Results

msNRP1 was successfully cloned and transduced in HEK293T cells. The supernatant of transduced cells was concentrated and evaluated for the production of msNRP1. ELISA results indicated that transduced cells secreted msNRP1. Growth cone collapse assay showed that Sema 3A activity was significantly reduced in the presence of the conditioned medium of msNRP1-transduced HEK293T cells. Conversely, a conditioned medium of non-transduced HEK293T cells could not effectively prevent Sema 3A growth cone collapse activity.

Conclusion

Our results indicated that msNRP1 was successfully produced in HEK293T cells. The secreted msNRP1 effectively prevented Sema 3A collapse activity. Therefore, msNRP1 can increase remyelination in MS lesions, although more studies using animal models are required.

A widespread viral entry mechanism: The C-end Rule motif-neuropilin receptor interaction

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 carboxy-terminal 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.

Neuropilin-1: A Key Protein to Consider in the Progression of Pediatric Brain Tumors

Neuropilins are transmembrane glycoproteins that play important roles in cardiovascular and neuronal development, as well as in immunological system regulations. NRP1 functions as a co-receptor, binding numerous ligands, such as SEMA 3 or VEGF and, by doing so, reinforcing their signaling pathways and can also interface with the cytoplasmic protein synectin. NRP1 is expressed in many cancers, such as brain cancers, and is associated with poor prognosis. The challenge today for patients with pediatric brain tumors is to improve their survival rate while minimizing the toxicity of current treatments. The aim of this review is to highlight the involvement of NRP1 in pediatric brain cancers, focusing essentially on the roles of NRP1 in cancer stem cells and in the regulation of the immune system. For this purpose, recent literature and tumor databases were analyzed to show correlations between NRP1 and CD15 (a stem cancer cells marker), and between NRP1 and PDL1, for various pediatric brain tumors, such as high- and low-grade gliomas, medulloblastomas, and ependymomas. Finally, this review suggests a relevant role for NRP1 in pediatric brain tumors progression and identifies it as a potential diagnostic or therapeutic target to improve survival and life quality of these young patients.

Axonal Growth Abnormalities Underlying Ocular Cranial Nerve Disorders

Abnormalities in cranial motor nerve development cause paralytic strabismus syndromes, collectively referred to as congenital cranial dysinnervation disorders, in which patients cannot fully move their eyes. These disorders can arise through one of two mechanisms: (a) defective motor neuron specification, usually by loss of a transcription factor necessary for brainstem patterning, or (b) axon growth and guidance abnormalities of the oculomotor, trochlear, and abducens nerves. This review focuses on our current understanding of axon guidance mechanisms in the cranial motor nerves and how disease-causing mutations disrupt axon targeting. Abnormalities of axon growth and guidance are often limited to a single nerve or subdivision, even when the causative gene is ubiquitously expressed. Additionally, when one nerve is absent, its normal target muscles attract other motor neurons. Study of these disorders highlights the complexities of axon guidance and how each population of neurons uses a unique but overlapping set of axon guidance pathways. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Semaphorin3F Drives Dendritic Spine Pruning Through Rho-GTPase Signaling

Dendritic spines of cortical pyramidal neurons are initially overproduced then remodeled substantially in the adolescent brain to achieve appropriate excitatory balance in mature circuits. Here we investigated the molecular mechanism of developmental spine pruning by Semaphorin 3F (Sema3F) and its holoreceptor complex, which consists of immunoglobulin-class adhesion molecule NrCAM, Neuropilin-2 (Npn2), and PlexinA3 (PlexA3) signaling subunits. Structure-function studies of the NrCAM-Npn2 interface showed that NrCAM stabilizes binding between Npn2 and PlexA3 necessary for Sema3F-induced spine pruning. Using a mouse neuronal culture system, we identified a dual signaling pathway for Sema3F-induced pruning, which involves activation of Tiam1-Rac1-PAK1-3 -LIMK1/2-Cofilin1 and RhoA-ROCK1/2-Myosin II in dendritic spines. Inhibitors of actin remodeling impaired spine collapse in the cortical neurons. Elucidation of these pathways expands our understanding of critical events that sculpt neuronal networks and may provide insight into how interruptions to these pathways could lead to spine dysgenesis in diseases such as autism, bipolar disorder, and schizophrenia.

Pancancer Analysis of Neurovascular-Related NRP Family Genes as Potential Prognostic Biomarkers of Bladder Urothelial Carcinoma

Background

Neurovascular-related genes have been implicated in the development of cancer. Studies have shown that a high expression of neuropilins (NRPs) promotes tumourigenesis and tumour malignancy.

Method

A multidimensional bioinformatics analysis was performed to examine the relationship between NRP genes and prognostic and pathological features, tumour mutational burden (TMB), microsatellite instability (MSI), and immunological features based on public databases and find the potential prognostic value of NRPs in pancancer.

Results

Survival analysis revealed that a low NRP1 expression in adrenocortical carcinoma (ACC), cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), low-grade glioma (LGG), and stomach adenocarcinoma (STAD) was associated with poor prognosis. A high NRP2 expression in bladder urothelial carcinoma (BLCA), kidney renal papillary cell carcinoma (KIRP), and mesothelioma (MESO) was associated with poor prognosis. Moreover, NRP1 and NRP2 were associated with TMB and MSI. Subsequent analyses showed that NRP1 and NRP2 were correlated with immune infiltration and immune checkpoints. Genome-wide association analysis revealed that the NRP1 expression was strongly associated with kidney renal clear cell carcinoma (KIRC), whereas the NRP2 expression was closely associated with BLCA. Ultimately, NRP2 was found to be involved in the development of BLCA.

Conclusions

Neurovascular-related NRP family genes are significantly correlated with cancer prognosis, TME, and immune infiltration, particularly in BLCA.

Neuropilin-2 and Its Transcript Variants Correlate with Clinical Outcome in Bladder Cancer

Urothelial bladder cancer ranks among the 10 most frequently diagnosed cancers worldwide. In our previous study, the transmembrane protein neuropilin-2 (NRP2) emerged as a predictive marker in patients with bladder cancer. NRP2 consists of several splice variants; the most abundant of these, NRP2a and NRP2b, are reported to have different biological functions in lung cancer progression. For other cancer types, there are no published data on the role of these transcript variants in cancer progression and the clinical outcome. Here, we correlate NRP2 and its two most abundant transcript variants, NRP2A and NRP2B, with the clinical outcome using available genomic data with subsequent validation in our own cohort of patients with muscle-invasive bladder cancer. In addition to NRP2, NRP1 and the NRP ligands PDGFC and PDGFD were studied. Only NRP2A emerged as an independent prognostic marker for shorter cancer-specific survival in muscle-invasive bladder cancer in our cohort of 102 patients who underwent radical cystectomy between 2008 and 2014 with a median follow-up time of 82 months. Additionally, we demonstrate that high messenger expression of NRP2, NRP1, PDGFC and PDGFD associates with a more aggressive disease (i.e., a high T stage, positive lymph node status and reduced survival).

Using organoids to study human brain development and evolution

Recent advances in methods for making cerebral organoids have opened a window of opportunity to directly study human brain development and disease, countering limitations inherent in non-human-based approaches. Whether freely patterned, guided into a region-specific fate or fused into assembloids, organoids have successfully recapitulated key features of in vivo neurodevelopment, allowing its examination from early to late stages. Although organoids have enormous potential, their effective use relies on understanding the extent of their limitations in accurately reproducing specific processes and components in the developing human brain. Here we review the potential of cerebral organoids to model and study human brain development and evolution and discuss the progress and current challenges in their use for reproducing specific human neurodevelopmental processes.

Activity-induced secretion of semaphorin 3A mediates learning

The semaphorin family is a well‐characterized family of secreted or membrane‐bound proteins that are involved in activity‐independent neurodevelopmental processes, such as axon guidance, cell migration, and immune functions. Although semaphorins have recently been demonstrated to regulate activity‐dependent synaptic scaling, their roles in Hebbian synaptic plasticity as well as learning and memory remain poorly understood. Here, using a rodent model, we found that an inhibitory avoidance task, a hippocampus‐dependent contextual learning paradigm, increased secretion of semaphorin 3A in the hippocampus. Furthermore, the secreted semaphorin 3A in the hippocampus mediated contextual memory formation likely by driving AMPA receptors into hippocampal synapses via the neuropilin1–plexin A4–semaphorin receptor complex. This signaling process involves alteration of the phosphorylation status of collapsin response mediator protein 2, which has been characterized as a downstream molecule in semaphorin signaling. These findings implicate semaphorin family as a regulator of Hebbian synaptic plasticity and learning.

The role of immune semaphorins in the pathogenesis of multiple sclerosis: Potential therapeutic targets

The immune and nervous systems possess a highly intricate network of synaptic connections, shared messenger molecules, and exquisite communication ways, allowing intercellular signal transduction. The semaphorins (Semas) were initially identified as axonal guidance molecules in the development of the nervous system but later were found to be implicated also in regulating the immune system, known in this case as the "immune Semas" or "immunoregulatory Semas". Increasingly, these molecules are involved in multiple aspects of both physiological and pathological immune responses and were recently indicated to take part in various immunological disorders, encompassing allergy, cancer, and autoimmunity. Semas transduce signals by connecting to their cognate receptors, namely, plexins and neuropilins. Some of them, like Sema-3F, have been found to function as the inducer of the remyelination process whereas some others, like Sema-3A and Sema-4D, act to inhibit this process, either directly or indirectly. Besides, Sema-4A is crucial to the differentiation of T helper type 1 (Th1) and Th17 cells that are potentially involved in the pathogenesis of multiple sclerosis (MS), an autoimmune disease of the central nervous system. This review aims to reveal the role of immune Semas in the pathogenesis of MS and its animal model, experimental autoimmune encephalomyelitis, focusing on the therapeutic usages of these molecules to treat this neurodegenerative disease.

Epigenetic targeting of neuropilin-1 prevents bypass signaling in drug-resistant breast cancer

Human epidermal growth factor receptor 2 (HER2)-amplified breast cancers are treated using targeted antibodies and kinase inhibitors, but resistance to these therapies leads to systemic tumor recurrence of metastatic disease. Herein, we conducted gene expression analyses of HER2 kinase inhibitor-resistant cell lines as compared to their drug-sensitive counterparts. These data demonstrate the induction of epithelial-mesenchymal transition (EMT), which included enhanced expression of fibroblast growth factor receptor 1 (FGFR1) and axonal guidance molecules known as neuropilins (NRPs). Immunoprecipitation of FGFR1 coupled with mass spectroscopy indicated that FGFR1 forms a physical complex with NRPs, which is enhanced upon induction of EMT. Confocal imaging revealed that FGFR1 and NRP1 predominantly interact throughout the cytoplasm. Along these lines, short hairpin RNA-mediated depletion of NRP1, but not the use of NRP1-blocking antibodies, inhibited FGFR signaling and reduced tumor cell growth in vitro and in vivo. Our results further indicate that NRP1 upregulation during EMT is mediated via binding of the chromatin reader protein, bromodomain containing 4 (BRD4) in the NRP1 proximal promoter region. Pharmacological inhibition of BRD4 decreased NRP1 expression and ablated FGF-mediated tumor cell growth. Overall, our studies indicate that NRPs facilitate aberrant growth factor signaling during EMT-associated drug resistance and metastasis. Pharmacological combination of epigenetic modulators with FGFR-targeted kinase inhibitors may provide improved outcomes for breast cancer patients with drug-resistant metastatic disease.

Vascular Endothelial Growth Factor Signaling in Models of Oxygen-Induced Retinopathy: Insights Into Mechanisms of Pathology in Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a leading cause of blindness in children worldwide. Blindness can occur from retinal detachment caused by pathologic retinal angiogenesis into the vitreous, termed intravitreal neovascularization (IVNV). Although agents that interfere with the bioactivity of vascular endothelial growth factor (VEGF) are now used to treat IVNV, concerns exist regarding the identification of optimal doses of anti-VEGF for individual infants and the effect of broad VEGF inhibition on physiologic angiogenesis in external organs or in the retina of a preterm infant. Therefore, it is important to understand VEGF signaling in both physiologic and pathologic angiogenesis in the retina. In this manuscript, we review the role of receptors that interact with VEGF in oxygen-induced retinopathy (OIR) models that represent features of ROP pathology. Specifically, we discuss our work regarding the regulation of VEGFR2 signaling in retinal endothelial cells to not only reduce severe ROP but also facilitate physiologic retinal vascular and neuronal development.

A comprehensive review of tumor proliferative and suppressive role of semaphorins and therapeutic approaches

Semaphorins have been traditionally known as axon guidance proteins that negatively regulate axonal growth. However, in the past couple of decades, their versatile role in so many other biological processes has come to prominence as well. One such example is their role in cancer. In this review article, the focus was on the tumor proliferative and tumor suppressive role of all 20 semaphorin family members under the 7 semaphorin classes found in vertebrates and invertebrates as well as the ongoing and emerging therapeutic approaches to combat semaphorin-mediated cancers. Except sema6C, 19 of the 20 non-viral semaphorin family members have been discovered to be associated with cancer in one way or another. Eleven semaphorin family members have been discovered to be tumor proliferative and 8 to be tumor suppressive. Six therapeutic avenues and their safety profiles have been discussed which are currently at use or at the various stages of development. Finally, perspectives on which approach is the best for treating cancers associated with semaphorins have been given.

The Role of Semaphorins in Metabolic Disorders

Semaphorins are a family originally identified as axonal guidance molecules. They are also involved in tumor growth, angiogenesis, immune regulation, as well as other biological and pathological processes. Recent studies have shown that semaphorins play a role in metabolic diseases including obesity, adipose inflammation, and diabetic complications, including diabetic retinopathy, diabetic nephropathy, diabetic neuropathy, diabetic wound healing, and diabetic osteoporosis. Evidence provides mechanistic insights regarding the role of semaphorins in metabolic diseases by regulating adipogenesis, hypothalamic melanocortin circuit, immune responses, and angiogenesis. In this review, we summarize recent progress regarding the role of semaphorins in obesity, adipose inflammation, and diabetic complications.

The Role of Rho GTPases in VEGF Signaling in Cancer Cells

Vascular endothelial growth factors (VEGFs) consist of five molecules (VEGFA through D as well as placental growth factor) which are crucial for regulating key cellular and tissue functions. The role of VEGF and its intracellular signaling and downstream molecular pathways have been thoroughly studied. Activation of VEGF signal transduction can be initiated by the molecules' binding to two classes of transmembrane receptors: (1) the VEGF tyrosine kinase receptors (VEGF receptors 1 through 3) and (2) the neuropilins (NRP1 and 2). The involvement of Rho GTPases in modulating VEGFA signaling in both cancer cells and endothelial cells has also been well established. Additionally, different isoforms of Rho GTPases, namely, RhoA, RhoC, and RhoG, have been shown to regulate VEGF expression as well as blood vessel formation. This review article will explore how Rho GTPases modulate VEGF signaling and the consequences of such interaction on cancer progression.

Semaphorins in Angiogenesis and Autoimmune Diseases: Therapeutic Targets?

The axonal guidance molecules, semaphorins, have been described to function both physiologically and pathologically outside of the nervous system. In this review, we focus on the vertebrate semaphorins found in classes 3 through 7 and their roles in vascular development and autoimmune diseases. Recent studies indicate that while some of these vertebrate semaphorins promote angiogenesis, others have an angiostatic function. Since some semaphorins are also expressed by different immune cells and are known to modulate immune responses, they have been implicated in autoimmune disorders such as multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis. We conclude this review by addressing strategies targeting semaphorins as potential therapeutic agents for angiogenesis and autoimmune diseases.

Roles of axon guidance molecules in neuronal wiring in the developing spinal cord

The spinal cord receives, relays and processes sensory information from the periphery and integrates this information with descending inputs from supraspinal centres to elicit precise and appropriate behavioural responses and orchestrate body movements. Understanding how the spinal cord circuits that achieve this integration are wired during development is the focus of much research interest. Several families of proteins have well-established roles in guiding developing spinal cord axons, and recent findings have identified new axon guidance molecules. Nevertheless, an integrated view of spinal cord network development is lacking, and many current models have neglected the cellular and functional diversity of spinal cord circuits. Recent advances challenge the existing spinal cord axon guidance dogmas and have provided a more complex, but more faithful, picture of the ontogenesis of vertebrate spinal cord circuits.

Neuropilin: Handyman and Power Broker in the Tumor Microenvironment

Neuropilin-1 and neuropilin-2 form a small family of transmembrane receptors, which, due to the lack of a cytosolic protein kinase domain, act primarily as co-receptors for various ligands. Performing at the molecular level both the executive and organizing functions of a handyman as well as of a power broker, they are instrumental in controlling the signaling of various receptor tyrosine kinases, integrins, and other molecules involved in the regulation of physiological and pathological angiogenic processes. In this setting, the various neuropilin ligands and interaction partners on various cells of the tumor microenvironment, such as cancer cells, endothelial cells, cancer-associated fibroblasts, and immune cells, are surveyed. The suitability of various neuropilin-targeting substances and the intervention in neuropilin-mediated interactions is considered as a possible building block of tumor therapy.

Neuropilin 1 modulates TGF‑β1‑induced epithelial‑mesenchymal transition in non‑small cell lung cancer

Previously, the authors reported that neuropilin-1 (NRP1) was significantly increased and acted as a vital promoter in the metastasis of non-small cell lung cancer (NSCLC). However, the regulatory mechanism of NRP1 in NSCLC cell migration and invasion remained unclear. The present study aimed to explore the regulatory mechanism of NRP1 in the transforming growth factor-β (TGF-β) 1-induced migration and invasion of NSCLC cells. The expression level of NRP1 was determined by RT-qPCR analysis in human tissue samples with or without lymph node metastasis. Transwell assay and wound healing assay were conducted to determine the cell migration. Lentivirus-mediated stable knockdown and overexpression of NRP1 cell lines were constructed. Exogenous TGF-β1 stimulation, SIS3 treatment, western blot analysis and in vivo metastatic model were utilized to clarify the underlying regulatory mechanisms. The results demonstrated that the expression of NRP1 was increased in metastatic NSCLC tissues. NRP1 promoted NSCLC metastasis in vitro and in vivo. The Transwell assays, wound healing assays and western blot analysis revealed that the knockdown of NRP1 significantly inhibited TGF-β1-mediated EMT and migratory and invasive capabilities of NSCLC. Furthermore, the overexpression of NRP1 weakened the inhibitory effect of SIS3 on the NSCLC migration and invasion. Co-IP assay revealed that NRP1 interacted with TGFβRII to induce EMT. On the whole, the findings of this study demonstrated that NRP1 was overexpressed in metastatic NSCLC tissues. NRP1 could contributes to TGF-β1-induced EMT and metastasis in NSCLC by binding with TGFβRII.

Inhibition of Semaphorin3A Promotes Ocular Dominance Plasticity in the Adult Rat Visual Cortex

Perineuronal nets (PNNs) are condensed structures in the extracellular matrix that mainly surround GABA-ergic parvalbumin-positive interneurons in the adult brain. Previous studies revealed a parallel between PNN formation and the closure of the critical period. Moreover, ocular dominance plasticity is enhanced in response to PNN manipulations in adult animals. However, the mechanisms through which perineuronal nets modulate plasticity are still poorly understood. Recent work indicated that perineuronal nets may convey molecular signals by binding and storing proteins with important roles in cellular communication. Here we report that semaphorin3A (Sema3A), a chemorepulsive axon guidance cue known to bind to important perineuronal net components, is necessary to dampen ocular dominance plasticity in adult rats. First, we showed that the accumulation of Sema3A in PNNs in the visual cortex correlates with critical period closure, following the same time course of perineuronal nets maturation. Second, the accumulation of Sema3A in perineuronal nets was significantly reduced by rearing animals in the dark in the absence of any visual experience. Finally, we developed and characterized a tool to interfere with Sema3A signaling by means of AAV-mediated expression of receptor bodies, soluble proteins formed by the extracellular domain of the endogenous Sema3A receptor (neuropilin1) fused to a human IgG Fc fragment. By using this tool to antagonize Sema3A signaling in the adult rat visual cortex, we found that the specific inhibition of Sema3A promoted ocular dominance plasticity. Thus, Sema3A accumulates in perineuronal nets in an experience-dependent manner and its presence in the mature visual cortex inhibits plasticity.

PlexinA1 is crucial for the midline crossing of callosal axons during corpus callosum development in BALB/cAJ mice

The corpus callosum (CC) is the biggest commissure that links cerebral hemispheres. Guidepost structures develop in the cortical midline during CC development and express axon guidance molecules that instruct neurons regarding the proper direction of axonal elongation toward and across the cortical midline. Neuropilin-1 (Npn1), a high affinity receptor for class 3 semaphorins (Sema3s) localized on cingulate pioneering axons, plays a crucial role in axon guidance to the midline through interactions with Sema3s. However, it remains unclear which type of Plexin is a component of Sema3 holoreceptors with Npn1 during the guidance of cingulate pioneering axons. To address the role of PlexinA1 in CC development, we examined with immunohistochemistry the localization of PlexinA1, Npn1, and Sema3s using embryonic brains from wild-type (WT) and PlexinA1-deficient (PlexinA1 knock-out (KO)) mice with a BALB/cAJ background. The immunohistochemistry confirmed the expression of PlexinA1 in callosal axons derived from the cingulate and neocortex of the WT mice on embryonic day 17.5 (E17.5) but not in the PlexinA1 KO mice. To examine the role of PlexinA1 in the navigation of callosal axons, the extension of callosal axons toward and across the midline was traced in brains of WT and PlexinA1 KO mice at E17.5. As a result, callosal axons in the PlexinA1 KO brains had a significantly lower incidence of midline crossing at E17.5 compared with the WT brains. To further examine the role of PlexinA1 in CC development, the CC phenotype was examined in PlexinA1 KO mice at postnatal day 0.5 (P0.5). Most of the PlexinA1 KO mice at P0.5 showed agenesis of the CC. These results indicate the crucial involvement of PlexinA1 in the midline crossing of callosal axons during CC development in BALB/cAJ mice.

Roles for VEGF-C/NRP-2 axis in regulating renal tubular epithelial cell survival and autophagy during serum deprivation

Vascular endothelial growth factor C (VEGF‐C) is an angiogenic and lymphangiogenic growth factor. Recent research has revealed the role for VEGF‐C in regulating autophagy by interacting with a nontyrosine kinase receptor, neuropilin‐2 (NRP–2). However, whether VEGF‐C participates in regulating cell survival and autophagy in renal proximal tubular cells is unknown. To address this question, we employed a cell modal of serum deprivation to verify the role of VEGF‐C and its receptor NRP–2 in regulating cell survival and autophagy in NRK52E cell lines. The results show that VEGF‐C rescued the loss of cell viability induced by serum deprivation in a concentration‐dependent manner. Furthermore, endogenous VEGF‐C was knocked down in NRK52E cells by using specific small‐interfering RNAs (siRNA), cells were more sensitive to serum deprivation–induced cell death. A similar increase in cell death rate was observed following NRP–2 depletion in serum‐starved NRK52E cells. Autophagy activity in serum‐starved NRK52E cells was confirmed by western blot analysis of microtubule‐associated protein‐1 chain 3 (LC3), immunofluorescence staining of endogenous LC3, and the formation of autophagosomes by electron microscopy. VEGF‐C or NRP–2 depletion further increased LC3 expression induced by serum deprivation, suggesting that VEGF‐C and NRP–2 were involved in controlling autophagy in NRK52E cells. We further performed autophagic flux experiments to identify that VEGF‐C promotes the activation of autophagy in serum‐starved NRK52E cells. Together, these results suggest for the first time that VEGF‐C/NRP–2 axis promotes survival and autophagy in NRK52E cells under serum deprivation condition.

Significance of the study

More researchers had focused on the regulation of autophagy in kidney disease. The effect of VEGF‐C on cell death and autophagy in renal epithelial cells has not been examined. We first identified the VEGF‐C as a regulator of cell survival and autophagy in NRK52E cell lines. And VEGF‐C/NRP–2 may mediate autophagy by regulating the phosphorylation of 4EBP1 and P70S6K. VEGF‐C treatment may be identified as a therapeutic target in renal injury repair due to its capacity to promote tubular cell survival in the future.

Expression of NRP-1 and NRP-2 in Endometrial Cancer

Background: Neuropilins (NRPs) participate in many processes related to cancer development such as angiogenesis, lymphangiogenesis and metastasis. Although endometrial cancer is one of the most common gynecological cancers, it has not been studied in terms of NRPs expression.

Objective: The aim of this study was to investigate the potential utility of NRPs as important factors in the diagnosis and treatment of endometrial cancer.

Methods: Our study consisted of 45 women diagnosed with endometrial cancer at the following degrees of histological differentiation: G1, 17; G2, 15; G3, 13 cases. The control group included 15 women without neoplastic changes. The immunohistochemical reactions were evaluated using light microscopy.

Results: We did not detect the expression of NRP-1 and NRP-2 in the control group. NRP-1 expression was found exclusively in cancer cells. It was higher in G2 and G3 and reached about 190% of G1. NRP-2 expression was observed in the endothelium and was similar across all three cancer grades. In cancer cells, NRP-2 expression increased with the degree of histological differentiation.

Conclusion: NRP1 and NRP2 are candidates for complementary diagnostic molecular markers and promising new targets for molecular, personalized anticancer therapies.

MiR-4500 Regulates PLXNC1 and Inhibits Papillary Thyroid Cancer Progression

Although most patients with papillary thyroid cancer (PTC) are curable, there are still a few patients showing poor outcomes and increased risk of secondary cancers after therapies. In this study, we aimed to investigate the correlation between miR-4500 and PTC and to explore its molecular functions. A total of 50 patients were included, and sonography and histological examinations were used for diagnosis. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied for detection of mRNA levels while Western blotting was used for measuring protein expression. Cell proliferation was tested using CCK-8 and colony formation assays. Caspase-3 activity and nucleosomal fragmentation assays were employed to test cell apoptosis. Cell invasive ability was measured using transwell assay. MiR-4500 target was identified using luciferase assay and RNA pull-down assay. MiR-4500 expression was significantly decreased in five PTC cell lines compared with Nthy-ori 3-1 cells and in PTC tissues compared with adjacent normal thyroid tissues, respectively. Decreased expression of miR-4500 showed lower survival rate, higher cancer stage, and lymphatic metastasis. Therefore, our results implied that miR-4500 could serve as a potential biomarker for PTC prognosis. Overexpression of miR-4500 repressed colony formation, proliferation, and invasiveness of PTC cells whereas increased cell apoptosis. We identified that PLXNC1 was a direct target of miR-4500. PLXNC1 knockdown showed similar effects on cell viability, colony formation, and cell apoptosis as overexpression of miR-4500 in PTC cells. In conclusion, miR-4500 inhibits the malignant transformation of PTC cells by directly targeting and repressing PLXNC1.

Therapeutic Effects of Synthetic Antimicrobial Peptides, TRAIL and NRP1 Blocking Peptides in Psoriatic Keratinocytes

Psoriasis is a chronic, recurrent, heterogeneous, cutaneous inflammatory skin disease for which there is no cure. It affects approximately 7.5 million people in the United States. Currently, several biologic agents that target different molecules implicated in the pathogenic processes of psoriasis are being assessed in diverse clinical studies. However, relapse usually occurs within weeks or months, meaning there is currently no cure for psoriasis. Therefore, recent studies have discovered diverse new potential treatments for psoriasis: inhibitors of bacteria such as Staphylococcus aureus, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and neuropilin 1 (NRP1). A promising approach that has recently been described involves modifying antimicrobial peptides to develop new cutaneous anti-bacterial agents that target inflammatory skin disease induced by Staphylococcus. Increased expression of TRAIL and its death receptors DR4 and DR5 has been implicated in the pathogenesis of plaque psoriasis. In addition, TRAIL has the ability to inhibit angiogenesis by inducing endothelial cell death and by negative regulation of VEGF-induced angiogenesis via caspase-8-mediated enzymatic and non-enzymatic functions. Since NRP1 regulates angiogenesis induced by multiple signals, including VEGF, ECM and semaphorins, and also initiates proliferation of keratinocytes through NF-κB signaling pathway in involved psoriatic skin, targeting NRP1 pathways may offer numerous windows for intervention in psoriasis. In this review, we will focus on the current knowledge about the emerging role of synthetic antimicrobial peptides, TRAIL and NRP1 blocking peptides in the pathogenesis and treatment of psoriasis.

DMRT5 Together with DMRT3 Directly Controls Hippocampus Development and Neocortical Area Map Formation

Mice that are constitutively null for the zinc finger doublesex and mab-3 related (Dmrt) gene, Dmrt5/Dmrta2, show a variety of patterning abnormalities in the cerebral cortex, including the loss of the cortical hem, a powerful cortical signaling center. In conditional Dmrt5 gain of function and loss of function mouse models, we generated bidirectional changes in the neocortical area map without affecting the hem. Analysis indicated that DMRT5, independent of the hem, directs the rostral-to-caudal pattern of the neocortical area map. Thus, DMRT5 joins a small number of transcription factors shown to control directly area size and position in the neocortex. Dmrt5 deletion after hem formation also reduced hippocampal size and shifted the position of the neocortical/paleocortical boundary. Dmrt3, like Dmrt5, is expressed in a gradient across the cortical primordium. Mice lacking Dmrt3 show cortical patterning defects akin to but milder than those in Dmrt5 mutants, perhaps in part because Dmrt5 expression increases in the absence of Dmrt3. DMRT5 upregulates Dmrt3 expression and negatively regulates its own expression, which may stabilize the level of DMRT5. Together, our findings indicate that finely tuned levels of DMRT5, together with DMRT3, regulate patterning of the cerebral cortex.

Neuropilins Controlling Cancer Therapy Responsiveness

Neuropilins (NRPs) are cell surface glycoproteins, acting as co-receptors for secreted Semaphorins (SEMAs) and for members of the vascular endothelial growth factor (VEGF) family; they have been initially implicated in axon guidance and angiogenesis regulation, and more recently in cancer progression. In addition, NRPs have been shown to control many other fundamental signaling pathways, especially mediated by tyrosine kinase receptors (RTKs) of growth factors, such as HGF (hepatocyte growth factor), PDGF (platelet derived growth factor) and EGF (epidermal growth factor). This enables NRPs to control a range of pivotal mechanisms in the cancer context, from tumor cell proliferation and metastatic dissemination, to tumor angiogenesis and immune escape. Moreover, cancer treatment failures due to resistance to innovative oncogene-targeted drugs is typically associated with the activity of alternative RTK-dependent pathways; and neuropilins’ capacity to control oncogenic signaling cascades supports the hypothesis that they could elicit such mechanisms in cancer cells, in order to escape cytotoxic stress and therapeutic attacks. Intriguingly, several studies have recently assayed the impact of NRPs inhibition in combination with diverse anti-cancer drugs. In this minireview, we will discuss the state-of-art about the relevance of NRPs as potential predictive biomarkers of drug response, and the rationale to target these proteins in combination with other anticancer therapies.

In vivo topology converts competition for cell-matrix adhesion into directional migration

When migrating in vivo, cells are exposed to numerous conflicting signals: chemokines, repellents, extracellular matrix, growth factors. The roles of several of these molecules have been studied individually in vitro or in vivo, but we have yet to understand how cells integrate them. To start addressing this question, we used the cephalic neural crest as a model system and looked at the roles of its best examples of positive and negative signals: stromal-cell derived factor 1 (Sdf1/Cxcl12) and class3-Semaphorins. Here we show that Sdf1 and Sema3A antagonistically control cell-matrix adhesion via opposite effects on Rac1 activity at the single cell level. Directional migration at the population level emerges as a result of global Semaphorin-dependent confinement and broad activation of adhesion by Sdf1 in the context of a biased Fibronectin distribution. These results indicate that uneven in vivo topology renders the need for precise distribution of secreted signals mostly dispensable.

Migrating cells encounter multiple signals such as extracellular matrix (ECM) and chemokinetic factors but how these integrate in vivo is unclear. Here, the authors report that overall control of cell-ECM adhesion by Sema3A and Sdf1 can be converted into directional migration by a biased ECM network.

Neuropilins in the Context of Tumor Vasculature

Neuropilin-1 and Neuropilin-2 form a small family of plasma membrane spanning receptors originally identified by the binding of semaphorin and vascular endothelial growth factor. Having no cytosolic protein kinase domain, they function predominantly as co-receptors of other receptors for various ligands. As such, they critically modulate the signaling of various receptor tyrosine kinases, integrins, and other molecules involved in the regulation of physiological and pathological angiogenic processes. This review highlights the diverse neuropilin ligands and interacting partners on endothelial cells, which are relevant in the context of the tumor vasculature and the tumor microenvironment. In addition to tumor cells, the latter contains cancer-associated fibroblasts, immune cells, and endothelial cells. Based on the prevalent neuropilin-mediated interactions, the suitability of various neuropilin-targeted substances for influencing tumor angiogenesis as a possible building block of a tumor therapy is discussed.