Netrin Receptor Research Articles

Netrin-1 controls inflammation in response to ischemic stroke through altering microglia phenotype.

The current approaches that are used to treat ischemic stroke suffer from poor targeting, lack of effectiveness, and potential off-target effects, necessitating the development of new therapeutic strategies to enhance neuronal cell survival and regeneration. This study aimed to investigate the role of microglial Netrin-1 in ischemic stroke, a topic that has not been fully understood. Netrin-1 levels and its primary receptor expressions were investigated in cerebral microglia from acute ischemic stroke patients and age-matched control subjects. A public database (GEO148350), which supplied RNAseq results for rat cerebral microglia in a middle cerebral artery occlusion (MCAO) model, was analyzed to assess the expression of Netrin-1, its major receptors, and genes related to macrophage function. A microglia-specific gene targeting approach and a delivery system allowing for crossing the blood-brain barrier were applied in a mouse model for ischemic stroke to investigate the role of microglial Netrin-1. Netrin-1 receptor signaling in microglia was observed and the effects on microglial phenotype, apoptosis, and migration were analyzed. Across human patients, rat and mouse models, activation of Netrin-1 receptor signaling was mainly conducted via its receptor UNC5a in microglia, which resulted in a shift in microglial phenotype towards an anti-inflammatory or M2-like state, leading to a reduction in apoptosis and migration of microglia. Netrin-1-induced phenotypic change in microglia exerted protective effects on neuronal cells in vivo during ischemic stroke. Our study highlights the potential of targeting Netrin-1 and its receptors as a promising therapeutic strategy for promoting post-ischemic survival and functional recovery.

Genetics of mirror movements identifies a multifunctional complex required for Netrin-1 guidance and lateralization of motor control.

Mirror movements (MM) disorder is characterized by involuntary movements on one side of the body that mirror intentional movements on the opposite side. We performed genetic characterization of a family with autosomal dominant MM and identified ARHGEF7, a RhoGEF, as a candidate MM gene. We found that Arhgef7 and its partner Git1 bind directly to Dcc. Dcc is the receptor for Netrin-1, an axon guidance cue that attracts commissural axons to the midline, promoting the midline crossing of axon tracts. We show that Arhgef7 and Git1 are required for Netrin-1-mediated axon guidance and act as a multifunctional effector complex. Arhgef7/Git1 activates Rac1 and Cdc42 and inhibits Arf1 downstream of Netrin-1. Furthermore, Arhgef7/Git1, via Arf1, mediates the Netrin-1-induced increase in cell surface Dcc. Mice heterozygous for Arhgef7 have defects in commissural axon trajectories and increased symmetrical paw placements during skilled walking, a MM-like phenotype. Thus, we have delineated how ARHGEF7 mutation causes MM.

Fetal alcohol exposure impairs learning and memory functions and elevates levels of various biochemical markers of Alzheimer's disease in the brain of 12-month-old rats.

Alcohol drinking during pregnancy often adversely affects brain development among offspring, inducing persistent central nervous system dysfunction. However, it is unknown whether fetal alcohol exposure (FAE) promotes the biochemical characteristics of Alzheimer's disease in offspring. We used a first- and second-trimester human equivalent rat model of FAE that involves feeding a liquid diet containing 6.7% v/v ethanol from gestational days 7 through 21 in Fischer-344 rats. Control rats were fed an isocaloric liquid diet or rat chow ad libitum. Pups were weaned on postnatal day 21 and housed by sex. They were used for behavioral and biochemical studies at about 12 months of age. Only one male or one female offspring from a litter was included in each experimental group. Fetal alcohol-exposed offspring had poorer learning and memory functions than controls. The experimental animals, both male and female, also had elevated levels of acetylcholinesterase (AChE) activity, hyperphosphorylated-tau protein, β-amyloid (Aβ) and Aβ1-42 proteins, β-site amyloid precursor protein cleaving enzyme 1 (BACE1), and Unc-5 netrin receptor C (UNC5C) proteins in the cerebral cortex and hippocampus at 12 months of age. These findings show that FAE increases the expression of some of the biochemical and behavioral phenotypes of Alzheimer's disease.

Axon guidance genes modulate neurotoxicity of ALS-associated UBQLN2.

Mutations in the ubiquitin (Ub) chaperone Ubiquilin 2 (UBQLN2) cause X-linked forms of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) through unknown mechanisms. Here, we show that aggregation-prone, ALS-associated mutants of UBQLN2 (UBQLN2ALS) trigger heat stress-dependent neurodegeneration in Drosophila. A genetic modifier screen implicated endolysosomal and axon guidance genes, including the netrin receptor, Unc-5, as key modulators of UBQLN2 toxicity. Reduced gene dosage of Unc-5 or its coreceptor Dcc/frazzled diminished neurodegenerative phenotypes, including motor dysfunction, neuromuscular junction defects, and shortened lifespan, in flies expressing UBQLN2ALS alleles. Induced pluripotent stem cells (iPSCs) harboring UBQLN2ALS knockin mutations exhibited lysosomal defects while inducible motor neurons (iMNs) expressing UBQLN2ALS alleles exhibited cytosolic UBQLN2 inclusions, reduced neurite complexity, and growth cone defects that were partially reversed by silencing of UNC5B and DCC. The combined findings suggest that altered growth cone dynamics are a conserved pathomechanism in UBQLN2-associated ALS/FTD.

Netrin-1 inducing antiapoptotic effect of acute myeloid leukemia cells in a concentration-dependent manner through the Unc-5 netrin receptor B-focal adhesion kinase axis

ABSTRACT Acute myeloid leukemia (AML) is a hematological malignancy that commonly occurs in children. The prognosis of pediatric AML is relatively poor, thus threatening the patient’s survival. The aberrant expression of the axon guidance factor, netrin-1, is observed in various types of malignancies, and it participates in the proliferation and apoptosis of tumor cells. Herein, we aimed to explore the role of netrin-1 in AML cells. Netrin-1 is highly expressed in AML patients. Proliferation and anti-apoptosis were observed in AML cells treated with netrin-1. The interaction between netrin-1 and Unc-5 netrin receptor B (UNC5B) was detected through coimmunoprecipitation, and UNC5B ribonucleic acid interference restrained the influence of netrin-1 on the AML cells. The phosphorylation of focal adhesion kinase-protein kinase B (FAK-Akt) was upregulated in AML cells treated with netrin-1. Both FAK and Akt inhibitors abrogated the effects of netrin-1 on the proliferation and apoptosis of AML cells. In conclusion, netrin-1 could promote the growth and reduce the apoptosis of AML cells in a concentration-dependent manner, and that these effects were mediated by activating the FAK-Akt signaling pathway via the UNC5B.

Fibronectin leucine-rich transmembrane protein 2 drives monocyte differentiation into macrophages via the UNC5B-Akt/mTOR axis.

Upon migrating into the tissues, hematopoietic stem cell (HSC)-derived monocytes differentiate into macrophages, playing a crucial role in determining innate immune responses towards external pathogens and internal stimuli. However, the regulatory mechanisms underlying monocyte-to-macrophage differentiation remain largely unexplored. Here we divulge a previously uncharacterized but essential role for an axon guidance molecule, fibronectin leucine-rich transmembrane protein 2 (FLRT2), in monocyte-to-macrophage maturation. FLRT2 is almost undetectable in human monocytic cell lines, human peripheral blood mononuclear cells (PBMCs), and mouse primary monocytes but significantly increases in fully differentiated macrophages. Myeloid-specific deletion of FLRT2 (Flrt2ΔMyel ) contributes to decreased peritoneal monocyte-to-macrophage generation in mice in vivo, accompanied by impaired macrophage functions. Gain- and loss-of-function studies support the promoting effect of FLRT2 on THP-1 cell and human PBMC differentiation into macrophages. Mechanistically, FLRT2 directly interacts with Unc-5 netrin receptor B (UNC5B) via its extracellular domain (ECD) and activates Akt/mTOR signaling. In vivo administration of mTOR agonist MYH1485 reverses the impaired phenotypes observed in Flrt2ΔMyel mice. Together, these results identify FLRT2 as a novel pivotal endogenous regulator of monocyte differentiation into macrophages. Targeting the FLRT2/UNC5B-Akt/mTOR axis may provide potential therapeutic strategies directly relevant to human diseases associated with aberrant monocyte/macrophage differentiation.

TOM-1/tomosyn acts with the UNC-6/netrin receptor UNC-5 to inhibit growth cone protrusion in Caenorhabditis elegans.

In the polarity/protrusion model of growth cone repulsion from UNC-6/netrin, UNC-6 first polarizes the growth cone of the VD motor neuron axon via the UNC-5 receptor, and then regulates protrusion asymmetrically across the growth cone based on this polarity. UNC-6 stimulates protrusion dorsally through the UNC-40/DCC receptor, and inhibits protrusion ventrally through UNC-5, resulting in net dorsal growth. Previous studies showed that UNC-5 inhibits growth cone protrusion via the flavin monooxygenases and potential destabilization of F-actin, and via UNC-33/CRMP and restriction of microtubule plus-end entry into the growth cone. We show that UNC-5 inhibits protrusion through a third mechanism involving TOM-1/tomosyn. A short isoform of TOM-1 inhibited protrusion downstream of UNC-5, and a long isoform had a pro-protrusive role. TOM-1/tomosyn inhibits formation of the SNARE complex. We show that UNC-64/syntaxin is required for growth cone protrusion, consistent with a role of TOM-1 in inhibiting vesicle fusion. Our results are consistent with a model whereby UNC-5 utilizes TOM-1 to inhibit vesicle fusion, resulting in inhibited growth cone protrusion, possibly by preventing the growth cone plasma membrane addition required for protrusion.

MP69-03 EXAMING THE LANDSCAPE OF CONCURRENT UPPER TRACT AND LOWER TRACT UROTHELIAL CARCINOMA USING SPATIAL TRANSCRIPTOMIC ANALYSIS

You have accessJournal of UrologyCME1 Apr 2023MP69-03 EXAMING THE LANDSCAPE OF CONCURRENT UPPER TRACT AND LOWER TRACT UROTHELIAL CARCINOMA USING SPATIAL TRANSCRIPTOMIC ANALYSIS Shreyas Naidu, Facundo Davaro, Xuefeng Wang, Elizabeth Davaro, Heather Huelster, Kyle Rose, Gustavo Borjas, Aram Vosoughi, and Roger Li Shreyas NaiduShreyas Naidu More articles by this author , Facundo DavaroFacundo Davaro More articles by this author , Xuefeng WangXuefeng Wang More articles by this author , Elizabeth DavaroElizabeth Davaro More articles by this author , Heather HuelsterHeather Huelster More articles by this author , Kyle RoseKyle Rose More articles by this author , Gustavo BorjasGustavo Borjas More articles by this author , Aram VosoughiAram Vosoughi More articles by this author , and Roger LiRoger Li More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003332.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Despite histologic similarities between upper-tract urothelial carcinoma (UTUC) and urothelial carcinoma of the bladder (UCB), there are differences in the clonal types, mutations, and immune landscape between these tumors. In this study, we performed multiplex spatial profiling of RNA on tumor samples from patients with concomitant UTUC and UCB in the evaluation of the tumors using the GeoMx™ Digital Spatial Profiling platform. METHODS: Three patients with concomitant high grade non-invasive UTUC and UCB were identified. Six FFPE samples from cystectomy and nephroureterectomy for the three patients were identified. A pathologist selected 18 regions of interest (ROIs), including tumor, tumor-stroma interface, and stroma area on each specimen. Multiplex IHC was performed on each sample with stains for DNA, Pan-CK, CD20 (B cells), and CD45 (immunocytes). The GeoMx™ Digital Spatial Profiling platform was used to sequence the RNA from the ROIs on each FFPE slide. Spatial deconvolution was used to determine ROI cellular composition. RESULTS: Multiplex IHC images demonstrated the increased infiltration of CD20 and CD45 immune cells in the UCB in compared to UTUC tumors; however, the proportion of inflammatory cells (i.e. T-cells, B-cells, plasma cells, T-regulatory cells, macrophages) are similar in different ROIs within each tumor and in UCB and UTUC tumors in each patient and even in samples from same sites among all patients. From the 11000+ genes identified through GeoMx analysis, we identified variable expression among UTUC and UCB samples. Notably, UNC5B, a gene that codes for a netrin receptor that is correlated with bladder cancer recurrence, was highly expressed in UCB. Additionally, UTUCs showed higher expression of histone regulatory genes (H1-3, H2BC5, H2BC8), which may lead to tumorigenesis and progression to muscle-invasive UC. CONCLUSIONS: UTUC demonstrates lower immune cells infiltration, consistent with previous UTUC studies; however, the proportion of inflammatory cells component is similar in different foci of the tumor and in concomitant UCB and UTUC tumors in each patient and even among all tumor samples from the same site. UNC5B, which has been associated with tumor recurrence, is highly expressed in UCB. UTUC patients showed higher expression of histone regulatory genes. Source of Funding: Moffitt Cancer Center © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e964 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Shreyas Naidu More articles by this author Facundo Davaro More articles by this author Xuefeng Wang More articles by this author Elizabeth Davaro More articles by this author Heather Huelster More articles by this author Kyle Rose More articles by this author Gustavo Borjas More articles by this author Aram Vosoughi More articles by this author Roger Li More articles by this author Expand All Advertisement PDF downloadLoading ...

Abstract P202: Proteomic Markers Associated With the Risk of Incident Hypertension in the Community: The Atherosclerosis Risk in Communities (ARIC) Study

Introduction: Proteins are involved in the pathophysiology of hypertension (HTN), but there are no large scale prospective proteomic analyses of incident HTN. Hypothesis: To identify and validate plasma proteins associated with incident HTN among a bi-racial cohort in the US. Methods: We quantified the associations of 4,955 plasma proteins (measured by SomaScan version 4 assay) with incident HTN over median follow-up of 11 years among 5,080 participants without baseline hypertension at ARIC visit 3 (1993-95). We then validated significant proteins from the primary analysis with incident HTN between visit 2 (n=6,810 during 1990-92) and visit 3 (median follow-up of 3.1y), to avoid including the same incident HTN cases in both analyses. Incident HTN was defined as systolic blood pressure (BP) ≥140, diastolic BP ≥90 mmHg, or HTN medication use. We ran multivariable Cox models and applied Benjamin-Hochberg procedure, with false discovery rate of 0.05, to account for multiple comparisons. Results: In the primary analysis with visit 3 as baseline (mean age 59y, 54% women, 13% Black), 3,828 participants (75%) developed HTN, and we found 55 proteins significantly associated with incident HTN. Among them, 14 proteins were validated using visit 2 data (Figure). Of those, 11 showed positive associations with HTN, and they are involved in glycoprotein degradation (e.g., MMP7, HTRA1, ASGR1, GUSB, CPM), cell adhesion (e.g., LGALS3BP and RET), and inflammation (e.g., CRP). In contrast, 3 proteins, renin ([REN]), netrin receptor ([UNC5D] apoptosis) and secretogranin-3([SCG3] endothelial cell growth), had inverse relationships with incident HTN. Further exploration showed a U-shaped association between renin and incident HTN. Conclusion: We identified several proteins associated with incident HTN, with plausible functions contributing to the development of HTN. These findings have implications on understanding mechanisms of HTN and potential targets for prevention and treatment.

Netrin-1 Promotes the Immunosuppressive Activity of MDSCs in Colorectal Cancer.

Myeloid-derived suppressive cells (MDSC) inhibit antitumor immunity and confer a survival advantage for tumor evasion. Tumor cells also support MDSC expansion and recruitment by secreting multiple growth factors and cytokines, but the mechanisms by which tumors affect MDSC function are not completely understood. Here, we found that the neuronal guidance protein netrin-1 was selectively secreted by MC38 murine colon cancer cells, which could enhance the immunosuppressive activity of MDSCs. MDSCs predominantly expressed one type of netrin-1 receptor, adenosine receptor 2B (A2BR). Netrin-1 interacted with A2BR on MDSCs to activate the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling pathway, which ultimately increased CREB phosphorylation in MDSCs. Furthermore, netrin-1 knockdown in tumor cells inhibited the immunosuppressive activity of MDSCs and restored antitumor immunity in MC38 tumor xenograft mice. Intriguingly, high netrin-1 in the plasma correlated with MDSCs in patients with colorectal cancer. In conclusion, netrin-1 significantly enhanced the immunosuppressive function of MDSCs through A2BR on MDSCs, thus promoting the development of tumors. These findings highlight that netrin-1 may regulate the abnormal immune response in colorectal cancer and may become a potential target for immunotherapy.

A Systematic Analysis of the Role of Unc-5 Netrin Receptor A (UNC5A) in Human Cancers.

Unc-5 netrin receptor A (UNC5A), a netrin family receptor, plays a key role in neuronal development and subsequent differentiation. Recently, studies have found that UNC5A plays an important role in multiple cancers, such as bladder cancer, non-small cell lung carcinoma, and colon cancer but its pan-cancer function is largely unknown. Herein, the R software and multiple databases or online websites (The Cancer Genome Atlas (TCGA), The Genotype-Tissue Expression (GTEx), The Tumor Immune Estimation Resource (TIMER), The Gene Set Cancer Analysis (GSCA), Gene Expression Profiling Interactive Analysis (GEPIA), and cBioPortal etc.) were utilized to examine the role of UNC5A in pan-cancer. UNC5A was found to be highly expressed across multiple human cancer tissues and cells, was linked to clinical outcomes of patients, and was a potential pan-cancer biomarker. The mutational landscape of UNC5A exhibited that patients with UNC5A mutations had poorer progress free survival (PFS) in head and neck squamous cell carcinoma (HNSC) and prostate adenocarcinoma (PRAD). Furthermore, UNC5A expression was associated with tumor mutation burden (TMB), neoantigen, tumor microenvironment (TME), tumor microsatellite instability (MSI), immunomodulators, immune infiltration, DNA methylation, immune checkpoint (ICP) genes, and drug responses. Our results suggest the potential of UNC5A as a pan-cancer biomarker and an efficient immunotherapy target, which may also guide drug selection for some specific cancer types in clinical practice.

Netrin-1 Stimulates Migration of Neogenin Expressing Aggressive Melanoma Cells.

Netrin-1 is a neural guidance factor that regulates migration and positioning of neural crest-derived cells during embryonic development. Depending on the type of Netrin-1 receptor expression, cells are either attracted or repulsed by Netrin-1. Postnatal expression of Netrin-1 is detected in brain, colon, liver, and kidney, which are common sites of cancer metastasis, including melanoma. Thus, understanding the dynamics between Netrin-1 and its receptors could explain the attraction of melanoma towards these Netrin-1-expressing tissues. Here, we investigate whether the Netrin-1-attractive receptor Neogenin can affect migration of melanoma cells towards a Netrin-1 source. Results from Western blot (WB) analysis show higher expression of Neogenin in aggressive compared to non-aggressive melanoma cells. Cell migration experiments show increased migration of Neogenin-expressing aggressive melanoma cells towards exogenous, soluble recombinant human Netrin-1 and towards a Netrin-1-expressing cell line. Furthermore, WB reveals ERK1/2 activation and increased N-cadherin expression in Neogenin-expressing aggressive melanoma cells treated with rhNetrin-1. Moreover, treatment with anti-Neogenin blocking antibody caused decreased migration towards Netrin-1-expressing cells and reduced ERK1/2 activity in Neogenin-expressing aggressive melanoma cells. These results suggest Neogenin may play a role during migration of melanoma cells towards Netrin-1 via ERK1/2 signaling.

Abstract 056: Transcriptomic Changes In Individual Cell Types Of The Arcuate Nucleus In The Mouse Deoxycorticosterone-acetate (doca)-salt Model Of Hypertension

Low-renin hypertension is common among the elderly, subjects of black African ancestry, those with heart or renal failure, and women with preeclampsia. Increased understanding of the causes and consequences of low-renin hypertension is necessary for the development of new efficacious and personalized therapeutics. One commonly employed preclinical model is “DOCA-salt” (DOCA), which causes robust hypertension, proteinuria, and organ damage. The arcuate nucleus of the hypothalamus (ARC) has been implicated in control of metabolic rate and blood pressure responses to DOCA. To characterize the DOCA related changes within the ARC, we used single nucleus RNA sequencing (snRNA-Seq) to individually interrogate the transcriptomes of numerous mouse ARC cell types. Male C57BL/6J mice 7 weeks-of-age underwent sham surgery or subcutaneous implantation of a 50mg DOCA pellet. All mice had water; DOCA mice were also provided 0.15 M NaCl drink ad libitum. Body composition was assessed by nuclear magnetic resonance. After 3 weeks, tissues were weighed and blood chemistries assessed. Features of DOCA treatment were consistent with previous studies, such as suppressed growth trajectory (sham n=7, DOCA n=8; -0.8±0.4g/3wk; p<0.01). Nuclei were isolated from ARC punches for snRNA-seq. Thirty-two unique cell type clusters were identified from snRNA-Seq, and DOCA differential gene expression (DEG) was determined using MAST. Two clusters were classified as resting (Cluster 23: DEGS up=11, down=35) and activated (Cluster 25: DEGS up=45, down=169) microglia subtypes. Analysis of proportions suggests there are fewer activated microglia in the DOCA ARC (dataset Sham=25%, DOCA = 75%; Cluster 25 Sham=37%, DOCA=63%; χ2 p = 0.0056), and DOCA may negatively impact activated microglia functions through decreased calcium signaling and netrin receptor activity. Sub-clustering of neuropeptide clusters resulted in the identification of 3 Agouti-related peptide sub-clusters. DOCA DEG enrichment terms indicated decreased neurotransmitter uptake, altered GABA synapse functions, and changed hormone secretion in the sub-clusters, respectively. These data provide novel insights into cell-specific molecular changes occurring in the ARC due to DOCA-salt hypertension.

Somatotopy of Mouse Spinothalamic Innervation and the Localization of a Noxious Stimulus Requires Deleted in Colorectal Carcinoma Expression by Phox2a Neurons.

Anterolateral system (AS) neurons transmit pain signals from the spinal cord to the brain. Their morphology, anatomy, and physiological properties have been extensively characterized and suggest that specific AS neurons and their brain targets are concerned with the discriminatory aspects of noxious stimuli, such as their location or intensity, and their motivational/emotive dimension. Among the recently unraveled molecular markers of AS neurons is the developmentally expressed transcription factor Phox2a, providing us with the opportunity to selectively disrupt the embryonic wiring of AS neurons to gain insights into the logic of their adult function. As mice with a spinal-cord-specific loss of the netrin-1 receptor deleted in colorectal carcinoma (DCC) have increased AS neuron innervation of ipsilateral brain targets and defective noxious stimulus localization or topognosis, we generated mice of either sex carrying a deletion of Dcc in Phox2a neurons. Such DccPhox2a mice displayed impaired topognosis along the rostrocaudal axis but with little effect on left-right discrimination and normal aversive responses. Anatomical tracing experiments in DccPhox2a mice revealed defective targeting of cervical and lumbar AS axons within the thalamus. Furthermore, genetic labeling of AS axons revealed their expression of DCC on their arrival in the brain, at a time when many of their target neurons are being born and express Ntn1 Our experiments suggest a postcommissural crossing function for netrin-1:DCC signaling during the formation of somatotopically ordered maps and are consistent with a discriminatory function of some of the Phox2a AS neurons.SIGNIFICANCE STATEMENT How nociceptive (pain) signals are relayed from the body to the brain remains an important question relevant to our understanding of the basic physiology of pain perception. Previous studies have demonstrated that the AS is a main effector of this function. It is composed of AS neurons located in the spinal cord that receive signals from nociceptive sensory neurons that detect noxious stimuli. In this study, we generate a genetic miswiring of mouse AS neurons that results in a decreased ability to perceive the location of a painful stimulus. The precise nature of this defect sheds light on the function of different kinds of AS neurons and how pain information may be organized.

Netrins and Netrin Receptors are Essential for Normal Targeting of Sensory Axons in the Zebrafish Olfactory Bulb

Olfactory sensory neurons that express related odorant receptors specifically target large identifiable neuropils called protoglomeruli when they first reach the olfactory bulb in the zebrafish. This crude odorant receptor-related mapping is further refined as odorant receptor-specific glomeruli segregate from protoglomeruli later in development. Netrins are a prominent class of axon guidance molecules whose contribution to olfactory circuit formation is poorly studied. Morpholino knock down experiments have suggested that Netrin/Dcc signaling is involved in normal protoglomerular targeting. Here we extend these findings with more detailed characterization and modeling of netrin expression, and by examining protoglomerular targeting in mutant lines fornetrin1a (ntn1a), netrin1b (ntn1b), and their receptorsunc5b,dcc, andneo1a. We confirm thatntn1a,ntn1b, anddccare required for normal protoglomerular guidance of a subset of olfactory sensory neurons that are labeled with the Tg(or111-7:IRES:Gal4) transgene. We also observe errors in the targeting of these axons inunc5bmutants, but not inneo1a mutants. Our findings are consistent with ntn1a andntn1bacting primarily as attractants for olfactory sensory neurons targeting the central zone protoglomerulus.

Effect of Netrin-1 on VEGFA Expression in T-ALL Cells and Its Related Mechanism

ELISA assays were applied to detect the levels of Netrin-1 and VEGFA in the bone marrow (BM) samples from children in the T-ALL and control group. The level of Netrin-1 and VEGFA were compared between control children and patients, and the liner correlation between Netrin-1 and VEGFA was analyzed. The T-ALL cells Jurkat and Molt-4 were culture in vitro, and the cells were treated with different concentration of Netrin-1 (0, 25, 50, 100 ng/ml) for 24 h, quantitative RT-PCR (qRT-PCR) and Western blot were used to detect the VEGFA expression in Jurkat, Molt-4 cells. The expression of Netrin-1 receptors in T-ALL cells was detected by qRT-PCR and the interaction between Netrin-1 and receptor in each cells was detected by co-IP. Furthermore, Western blot was used to detect the phosphorylation level of key prateins of AKT signal transduction pathway including Akt and mTOR in T-ALL cells treated with Netrin-1 (100 ng/ml). The expression of VEGFA and phosphorylation of AKT pathway transducers were detected by Western blot, after T-ALL cells treated with Netrin-1 (100 ng/ml) combined with inhibitors specific to Akt or mTOR. The expression level of Netrin-1 and VEGFA in T-ALL patients BM samples were both signi-ficantly higher than that of control group. And the expression level of Netrin-1 was positively correlated with that of VEGFA（r2=0974). With the increase of Netrin-1 concentration, the expression level of VEGFA also increased(P<0.05）. Netrin-1 interacted with its receptor, integrin-β4 at the Netrin-1 concentration of 100 ng/ml. Further, the treatment of Netrin-1 could increase the phosphorylation of Akt and mTOR, which were the key transducers of AKT pathway. After treatment of T-ALL cells with Netrin-1 (100 ng/mL) and Akt inhibitor, the expression of VEGFA and phosphorylation of Akt or mTOR decreased. When the cells were treated with Netrin-1(100 ng/ml) and mTOR inbititor, the phosphorylation level of mTOR and the expression of VEGFA decreased, the phosphorylation level of Akt increased. The expression of Netrin-1 and VEGFA in bone marrow of childred with T-ALL were abnormal, and there was a linear relationship between them. Netrin-1 can interact with its receptor, integrin-β4 and activate AKT transduction pathway to elevate the expression of VEGFA in T-ALL cells.

Omics approaches to discover pathophysiological pathways contributing to human pain.

Omics approaches to discover pathophysiological pathways contributing to human pain.

Abstract 360: Methyl-cantharidimide (MCA) can induce apoptosis by activating UNC5B-Netrin-1-DAPK pathway in hepatocellular carcinoma

Abstract In this study, we investigated the underlying mechanism of action of methyl-cantharidimide (MCA), a cantharidin (CTD) analog, as an anticancer drug, in resistant cancer cells overexpressing either ABCB1 or ABCG2 and in cisplatin-resistant cancer cells. The results indicated that: (i) MCA was efficacious in the ABCB1-overexpressing cell line, KB-C2, the ABCG2-overexpressing cell line, NCI-H460/MX20 and in the cisplatin resistant cancer cell lines, KCP-4 and BEL-7404/CP20; (ii) MCA induced apoptosis in both BEL-7404 and BEL-7404/CP20 cancer cells and arrested both BEL-7404 and BEL-7404/CP20 cancer cells in the G0/G1 phase of the cell cycle; (iii) MCA upregulated the expression level of the protein, unc-5 netrin receptor B (UNC5B) in HepG2 and BEL-7404 cancer cells. (iv) MCA can activate UNC5B-Netrin-1-DAPK apoptosis pathway in hepatocellular carcinoma cells. Overall, our results indicated that MCA's efficacy in multiple cancer cell lines is due to the activation of UNC5B-Netrin-1-DAPK apoptosis pathway and cell cycle arrest in the G0/G1 phase. Citation Format: Yi-Dong Li, Yong Mao, Xing-Duo Dong, Zi-Ning Lei, Yuqi Yang, Lizhu Lin, Dong-Hua Yang, Zhe-Sheng Chen. Methyl-cantharidimide (MCA) can induce apoptosis by activating UNC5B-Netrin-1-DAPK pathway in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 360.

Serum netrin-1 and netrin receptor levels in fibromyalgia and osteoarthritis.

Objectives This study aims to define serum levels of netrin-1 and netrin receptors in patients with fibromyalgia (FM) and osteoarthritis (OA). Patients and methods This cross-sectional study was conducted with a total of 150 female participants (mean age: 47.2±16.1 years; range, 18 to 89 years) at Fırat University between June 2016 and December 2016. The participants were evaluated in three groups: the FM group with 50 patients, the OA group with 50 patients, and the control group, which included 50 healthy volunteers. Netrin-1, netrin receptors (DCC, UNC5B, and UNC5D), interleukin (IL)-6, IL-10, and IL-17 levels were analyzed by the enzyme-linked immunosorbent assay from the serum samples of the participants. Results The level of serum netrin-1 was significantly lower in the FM group than in the control and OA groups (p<0.01 and p<0.001, respectively). However, the difference between patients with OA and healthy controls in terms of netrin-1 was not statistically significant (p>0.05). In addition, serum levels of netrin receptors and cytokines in the FM group were similar to the control group (p>0.05). However, serum DCC, UNC5D, IL-6, and IL-10 levels were higher in the OA group compared to the control group (p<0.001, p<0.05, p<0.01, and p<0.001, respectively). Conclusion Serum netrin-1 level is suppressed in FM, which suggests that netrin-1 is influential in FM pathogenesis.

Transsynaptic cerebellin 4–neogenin 1 signaling mediates LTP in the mouse dentate gyrus

Five decades ago, long-term potentiation (LTP) of synaptic transmission was discovered at entorhinal cortex→dentate gyrus (EC→DG) synapses, but the molecular determinants of EC→DG LTP remain largely unknown. Here, we show that the presynaptic neurexin–ligand cerebellin-4 (Cbln4) is highly expressed in the entorhinal cortex and essential for LTP at EC→DG synapses, but dispensable for basal synaptic transmission at these synapses. Cbln4, when bound to cell-surface neurexins, forms transcellular complexes by interacting with postsynaptic DCC (deleted in colorectal cancer) or neogenin-1. DCC and neogenin-1 act as netrin and repulsive guidance molecule-a (RGMa) receptors that mediate axon guidance in the developing brain, but their binding to Cbln4 raised the possibility that they might additionally function in the mature brain as postsynaptic receptors for presynaptic neurexin/Cbln4 complexes, and that as such receptors, DCC or neogenin-1 might mediate EC→DG LTP that depends on Cbln4. Indeed, we observed that neogenin-1, but not DCC, is abundantly expressed in dentate gyrus granule cells, and that postsynaptic neogenin-1 deletions in dentate granule cells blocked EC→DG LTP, but again did not affect basal synaptic transmission similar to the presynaptic Cbln4 deletions. Thus, binding of presynaptic Cbln4 to postsynaptic neogenin-1 renders EC→DG synapses competent for LTP, but is not required for establishing these synapses or for otherwise enabling their function.