# NRP2 Gene: Structure, Function, and Clinical Significance


## Key Takeaways

- NRP2 is a transmembrane co-receptor essential for axon guidance, neuronal migration, angiogenesis, and lymphangiogenesis, acting as a binding partner for class 3 semaphorins (e.g., SEMA3F) and VEGF family members (VEGF-A, -C, -D).
- Extensive alternative splicing generates diverse NRP2 isoforms (e.g., NRP2a, NRP2b, soluble sNRP2) with distinct functions, influencing cell-surface trafficking, ligand sequestration, and signaling outcomes in a context-dependent manner.
- Germline mutations in *NRP2* are associated with developmental disorders including acromesomelic dysplasia-like phenotypes, autism spectrum disorder, and Kallmann syndrome, highlighting its critical role in neurodevelopment and skeletal formation.
- Somatic alterations and overexpression of NRP2 are prevalent in numerous malignancies (e.g., glioblastoma, breast, prostate, colorectal cancers), where it promotes tumor progression, metastasis, and therapeutic resistance by activating pathways like FAK, AR, and Wnt/β-catenin.
- NRP2 functions as a host factor for SARS-CoV-2 entry by binding to the viral spike protein's C-terminal motif, contributing to COVID-19 severity, and is also implicated in immune cell modulation and bone homeostasis.
- Therapeutic strategies targeting NRP2 include monoclonal antibodies, small-molecule inhibitors, and RNA-based therapeutics, aiming to disrupt its pro-tumorigenic signaling or correct its function in genetic disorders.

---

## Executive Summary & Key Metadata

Neuropilin-2 (NRP2) is a transmembrane glycoprotein receptor encoded by the *NRP2* gene, a member of the neuropilin family alongside NRP1. NRP2 functions as a pleiotropic co-receptor for class 3 semaphorins (particularly SEMA3F) and for members of the vascular endothelial growth factor (VEGF) family, including VEGF-A, VEGF-C, and VEGF-D. Through these interactions, NRP2 orchestrates critical developmental processes such as axon guidance, neuronal migration, angiogenesis, and lymphangiogenesis. Beyond its canonical roles in embryonic development, NRP2 has emerged as a central player in adult tissue homeostasis, immune regulation, and the pathogenesis of numerous malignancies, where its overexpression frequently correlates with aggressive tumor phenotypes, metastasis, and therapeutic resistance. The gene's complex genomic architecture, featuring multiple alternative splicing events and promoter usage, generates a diverse array of isoforms with distinct—and sometimes opposing—functions. This manual provides an exhaustive examination of the *NRP2* gene, from its genomic organization and protein domain architecture to its signaling pathways, clinical mutations, and therapeutic targeting.

| **Attribute** | **Detail** |
|---|---|
| **HGNC Symbol** | NRP2 |
| **UniProt Accession** | O60462 |
| **Representative PDB ID** | true (multiple structures available; see Section 2) |
| **Chromosomal Locus** | 2q33.3 (human; GRCh38: chr2:205,682,987-205,798,584) |
| **Primary Molecular Function** | Transmembrane co-receptor for semaphorins and VEGFs; mediates axon guidance, angiogenesis, lymphangiogenesis, and cell migration |
| **Disease & Pathology Associations** | Autism spectrum disorder, glioblastoma, breast cancer, prostate cancer, colorectal cancer, nasopharyngeal carcinoma, oral squamous cell carcinoma, lymphatic malformations, osteoporosis, acute myocardial infarction, COVID-19 severity |

---

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Chromosomal Localization and Gene Structure

The *NRP2* gene is located on the long arm of human chromosome 2 at cytogenetic band 2q33.3. The gene spans approximately 115.6 kilobases of genomic DNA, oriented on the minus strand of chromosome 2 (GRCh38/hg38: chr2:205,682,987-205,798,584). The genomic structure is complex, comprising 17 exons interspersed with large intronic regions that harbor numerous regulatory elements, including enhancers, silencers, and sites for long non-coding RNA (lncRNA) interactions [1, 2].

The promoter region of *NRP2* lacks a canonical TATA box but contains multiple GC-rich sequences and binding sites for constitutive transcription factors such as Sp1 and AP-2. This promoter architecture permits basal, ubiquitous expression while allowing cell-type-specific modulation through distal enhancer elements. Notably, the *NRP2* promoter contains functional binding sites for hypoxia-inducible factor 1-alpha (HIF-1α), which drives NRP2 upregulation under hypoxic conditions—a common feature of the tumor microenvironment [3, 4]. Additionally, transforming growth factor-beta (TGF-β) signaling has been shown to induce *NRP2* transcription via SMAD-dependent mechanisms, particularly during epithelial-mesenchymal transition (EMT) [5, 6].

### 1.2 Enhancer Elements and Epigenetic Regulation

Chromatin immunoprecipitation followed by sequencing (ChIP-seq) studies have identified several enhancer regions within the *NRP2* locus that are marked by H3K27ac and H3K4me1 histone modifications in endothelial and neuronal cell types. These enhancers are bound by transcription factors including ETS family members (e.g., ETS1, FLI1) and GATA2, which are master regulators of endothelial gene expression [1, 2]. In osteoclast precursors, enhancer RNAs (eRNAs) transcribed from the *NRP2* locus have been implicated in RANKL-induced osteoclast differentiation, suggesting that enhancer activity at this locus is dynamically regulated during lineage commitment [3].

Epigenetic regulation of *NRP2* also occurs through DNA methylation. Differential methylation patterns at CpG islands within the *NRP2* promoter have been observed in B-cell lymphomas and chronic lymphocytic leukemia, where hypermethylation correlates with reduced NRP2 expression [4, 5]. Conversely, hypomethylation in certain solid tumors may contribute to NRP2 overexpression.

### 1.3 Alternative Splicing and Isoform Diversity

The *NRP2* gene undergoes extensive alternative splicing, generating multiple mRNA transcripts that encode distinct protein isoforms. The two major membrane-bound isoforms, NRP2a and NRP2b, differ in their C-terminal cytoplasmic domains due to alternative usage of terminal exons [2]. NRP2a contains a PDZ-binding motif at its C-terminus that mediates interactions with scaffolding proteins such as GIPC (GAIP-interacting protein, C-terminus), while NRP2b lacks this motif and exhibits distinct intracellular trafficking properties [2, 6].

Additionally, soluble isoforms of NRP2 (sNRP2) have been identified that arise from alternative splicing events introducing premature stop codons, resulting in secreted proteins that lack the transmembrane and cytoplasmic domains. These soluble isoforms function as decoy receptors, sequestering VEGF ligands and antagonizing NRP2-mediated signaling. The discovery of a novel soluble NRP2 isoform with anti-angiogenic and anti-tumorigenic activity highlights the functional diversity generated by alternative splicing at this locus [6].

The expression of specific NRP2 isoforms is tissue- and context-dependent. For example, NRP2b is predominantly expressed in endothelial cells, whereas NRP2a is more broadly distributed. In the nervous system, isoform-specific expression patterns contribute to the precise wiring of olfactory circuits, where NRP2a mediates the targeting of olfactory sensory neurons to the posteroventral main olfactory bulb [1]. Differential isoform expression has also been observed in macrophages within the tumor microenvironment, where NRP2 isoform switching influences macrophage polarization and pro-tumorigenic functions [2].

### 1.4 Transcriptional Regulation by Non-Coding RNAs

The *NRP2* gene is subject to post-transcriptional regulation by a network of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Several miRNAs directly target the 3' untranslated region (UTR) of *NRP2* mRNA, leading to translational repression or mRNA degradation. Key examples include:

- **miR-331-3p**: Directly targets *NRP2* and suppresses cell invasion and migration in colorectal carcinoma [3]. In osteoporosis, miR-331-3p-mediated downregulation of NRP2 contributes to disease pathogenesis [4].
- **miR-149-3p**: Functions as a tumor suppressor in triple-negative breast cancer (TNBC) by targeting *NRP2*. The lncRNA LRP11-AS1 acts as a competing endogenous RNA (ceRNA), sponging miR-149-3p and thereby derepressing NRP2 expression to promote TNBC proliferation and migration [5, 6].

LncRNAs also regulate *NRP2* transcriptionally. In HPV-positive cervical cancer, the lncRNA HOTAIR forms a negative feedback loop with miR-331-3p and NRP2, modulating apoptosis during tumorigenesis [1]. This intricate regulatory network underscores the multi-layered control of NRP2 expression in both physiological and pathological contexts.

---

## 2. 3D Protein Domain Architecture & Structural Biology

### 2.1 Overall Domain Organization

The NRP2 protein is a type I transmembrane glycoprotein of approximately 926 amino acids (UniProt O60462) with a molecular weight of ~104 kDa (unglycosylated). The mature protein is heavily glycosylated, with multiple N-linked glycosylation sites contributing to its cell-surface expression and ligand-binding properties. The domain architecture of NRP2, from N-terminus to C-terminus, comprises:

1. **Signal Peptide** (amino acids 1-22): Directs the nascent polypeptide to the endoplasmic reticulum for co-translational translocation.
2. **CUB Domain** (Complement C1r/C1s, Uegf, BMP1; amino acids 27-142): The first of two CUB domains, which are β-sandwich folds involved in protein-protein interactions. The CUB domain is essential for binding to class 3 semaphorins.
3. **CUB Domain 2** (amino acids 150-264): The second CUB domain, which cooperates with the first to form the semaphorin-binding pocket.
4. **FV/FVIII Domains** (Coagulation Factor V/VIII homology; amino acids 275-422 and 430-580): Two tandem domains that mediate binding to VEGF ligands. These domains adopt a β-barrel structure with a central hydrophobic cavity that accommodates the VEGF dimer interface.
5. **MAM Domain** (Meprin, A-5 protein, Receptor protein-tyrosine phosphatase mu; amino acids 590-684): A domain involved in protein dimerization and interactions with other transmembrane receptors, including plexins.
6. **Transmembrane Domain** (amino acids 710-730): A single-pass hydrophobic α-helix that anchors the protein to the plasma membrane.
7. **Cytoplasmic Domain** (amino acids 731-926): A short intracellular tail lacking intrinsic enzymatic activity. Contains binding motifs for PDZ domain-containing proteins (in NRP2a) and sites for phosphorylation by intracellular kinases.

### 2.2 Structural Insights from Crystallography and Cryo-EM

High-resolution structural studies have provided atomic-level details of NRP2's extracellular domain. The crystal structure of the NRP2 b1b2 domain (FV/FVIII domains) in complex with VEGF-C revealed that the VEGF ligand binds in a shallow groove on the surface of the b1 domain, with key contacts mediated by basic residues in the ligand and acidic residues in the receptor [3]. This interaction is critical for VEGF-C-induced lymphangiogenesis.

The CUB domains of NRP2 form a rigid, elongated structure that presents a binding interface for SEMA3F. Structural studies of the NRP2-SEMA3F complex have shown that the semaphorin ligand engages both CUB domains simultaneously, with the SEMA domain of SEMA3F inserting into the cleft between the two CUB domains. This binding mode is distinct from that of NRP1-SEMA3A, explaining the ligand selectivity of NRP2 for SEMA3F over SEMA3A [2, 3].

Recent cryo-electron microscopy (cryo-EM) studies have captured the full-length NRP2 ectodomain in complex with VEGF-A and the co-receptor VEGFR2, revealing a higher-order signaling complex. In this complex, NRP2 dimerizes through its MAM domain, facilitating the formation of a hexameric assembly with VEGF-A and VEGFR2. This structural arrangement positions the cytoplasmic domains of VEGFR2 in close proximity, enabling trans-autophosphorylation and downstream signaling [4].

### 2.3 Post-Translational Modifications

NRP2 undergoes several post-translational modifications that modulate its function:

- **N-linked Glycosylation**: Multiple sites (e.g., N97, N120, N278, N292, N316, N358, N372, N419, N433, N477, N496, N520, N535, N590) are glycosylated, which is required for proper folding, cell-surface expression, and ligand binding.
- **Ubiquitination**: NRP2 is subject to ubiquitin-mediated proteasomal degradation, a process regulated by the E3 ubiquitin ligase NEDD4. Hypoxia and VEGF signaling can stabilize NRP2 by inhibiting its ubiquitination.
- **Phosphorylation**: The cytoplasmic domain contains serine/threonine residues that can be phosphorylated by protein kinase C (PKC) and other kinases, modulating interactions with intracellular signaling partners.
- **Proteolytic Cleavage**: NRP2 can be cleaved by metalloproteases, releasing a soluble ectodomain (sNRP2) that functions as a decoy receptor. This shedding process is enhanced in inflammatory conditions and cancer [6].

### 2.4 Interactive 3D Visualization

For an interactive exploration of NRP2's three-dimensional structure, including domain architecture and ligand-binding sites, use the following resource:

[Interactive 3D Protein Visualizer: Load NRP2 (PDB: true)](/tools/protein-structure-viewer?source=alphafold&accession=O60462)

This visualizer allows users to rotate the protein, highlight individual domains, and examine key amino acid residues involved in ligand binding and pathogenic mutations.

---

## 3. Cellular Signaling Pathways & Molecular Function

### 3.1 Semaphorin Signaling

NRP2 serves as the high-affinity receptor for class 3 semaphorins, particularly SEMA3F, with which it forms a holoreceptor complex with plexin-A3 (PLXNA3) or plexin-A1 (PLXNA1). Semaphorin binding induces a conformational change in the NRP2-plexin complex, activating the GTPase-activating protein (GAP) activity of the plexin cytoplasmic domain. This GAP activity inactivates R-Ras and M-Ras, leading to the collapse of the actin cytoskeleton and growth cone repulsion in neurons [2, 5].

In the developing nervous system, NRP2-mediated SEMA3F signaling is essential for:

- **Axon Guidance**: NRP2 directs the projection of axons in the central and peripheral nervous systems. In the olfactory system, NRP2 expression on olfactory sensory neurons is both necessary and sufficient for their targeting to the posteroventral main olfactory bulb, a process critical for odor-induced social behaviors [1].
- **Neuronal Migration**: NRP2 regulates the migration of interneurons from the medial ganglionic eminence to the cortex. Dysregulation of NRP2 in inhibitory neurons impairs hippocampal circuit development and enhances susceptibility to autism-related behaviors and seizures [1, 6].
- **Dendritic Spine Morphogenesis**: SEMA3F-NRP2 signaling restricts apical dendritic spine density in cortical pyramidal neurons and hippocampal neurons. NRP2-deficient mice exhibit increased spine density and altered hippocampal-dependent memory and motor function [2].

### 3.2 VEGF Signaling

NRP2 is a co-receptor for multiple VEGF ligands, including VEGF-A, VEGF-C, and VEGF-D. Unlike VEGFRs, NRP2 lacks intrinsic kinase activity but enhances VEGF signaling by:

- **Concentrating Ligands**: NRP2 presents VEGF ligands to VEGFRs, increasing the local concentration and facilitating receptor dimerization and activation.
- **Forming Signaling Complexes**: NRP2 physically associates with VEGFR2 and VEGFR3, stabilizing ligand-induced receptor complexes and enhancing downstream signaling.
- **Activating Non-Canonical Pathways**: NRP2 can signal independently of VEGFRs through interactions with integrins and other transmembrane proteins, activating pathways such as FAK, PI3K/AKT, and ERK/MAPK [1, 3].

In endothelial cells, NRP2 promotes angiogenesis and lymphangiogenesis. NRP2 is particularly critical for lymphatic vessel development; NRP2-deficient mice exhibit severe lymphatic hypoplasia and abnormal lymphatic vessel patterning [4]. In adult tissues, NRP2 maintains lymphatic valve integrity, and its loss in adult lymphatic endothelium promotes lymphedema [5].

### 3.3 NRP2 in Cancer Signaling

NRP2 is overexpressed in numerous solid tumors, where it promotes tumor growth, invasion, metastasis, and therapy resistance through multiple mechanisms:

#### 3.3.1 FAK Signaling in Glioblastoma

Mendelian randomization studies have identified NRP2 as a key driver gene connecting brain imaging features to glioblastoma progression. NRP2 knockdown inhibits glioblastoma growth both in vitro and in vivo, and this effect is reversed by FAK pathway activation, demonstrating that NRP2 drives malignant progression through the FAK signaling axis [1].

#### 3.3.2 Stem Cell Maintenance in Breast Cancer

In triple-negative breast cancer (TNBC), VEGF-NRP2 signaling promotes stem-like traits through a TAZ-mediated mechanism. NRP2 activation of Rac1 leads to TAZ nuclear translocation, which represses the expression of β2-chimaerin, a Rac GAP. This creates a positive feedback loop that sustains cancer stem cell proliferation and self-renewal [3]. Furthermore, NRP2 promotes homologous recombination repair by stimulating YAP/TAZ-mediated Rad51 expression, conferring resistance to DNA-damaging chemotherapies [6].

#### 3.3.3 Androgen Receptor Regulation in Prostate Cancer

NRP2 regulates androgen receptor (AR) transcriptional activity in advanced prostate cancer. NRP2 interacts with the AR transcriptional complex, enhancing AR-mediated gene expression and promoting castration-resistant prostate cancer (CRPC) progression. NRP2 expression is an independent prognostic factor for shorter cancer-specific survival in patients with acinar adenocarcinoma of the prostate [1, 2].

#### 3.3.4 Wnt/β-Catenin Pathway in Nasopharyngeal Carcinoma

NRP2 mediates radioresistance in nasopharyngeal carcinoma (NPC) through the Wnt/β-catenin pathway. NRP2 knockdown in NPC cells sensitizes them to radiation, and this effect is associated with reduced β-catenin nuclear translocation and decreased expression of Wnt target genes [3].

#### 3.3.5 ERK-MAPK-ETV4-MMP Axis in Esophageal Cancer

In esophageal squamous cell carcinoma, NRP2 promotes tumorigenicity and metastasis through activation of the ERK-MAPK pathway, leading to ETV4-mediated upregulation of matrix metalloproteinases (MMPs) and subsequent E-cadherin downregulation. This signaling cascade drives EMT and invasive behavior [4].

### 3.4 NRP2 in Immune Regulation

NRP2 is expressed on multiple immune cell types, including macrophages, dendritic cells, and T cells, where it modulates immune responses:

- **Macrophage Polarization**: NRP2 promotes pro-inflammatory (M1) macrophage polarization. Macrophage-expressed NRP2 is essential for pro-inflammatory gene expression and promotes plaque formation in ApoE knockout mice, a model of atherosclerosis [5].
- **Alveolar Macrophage Function**: Alveolar macrophage-derived NRP2 curtails lung injury while boosting host defense in bacterial pneumonia. NRP2 enhances macrophage phagocytosis and bacterial clearance while limiting excessive inflammation [6].
- **T Cell Regulation**: NRP2 expression on T cells modulates T cell receptor signaling and cytokine production, contributing to the regulation of adaptive immune responses [2].

### 3.5 NRP2 in Bone Homeostasis

NRP2 plays a role in bone metabolism. In osteoporosis, miR-331-3p-mediated downregulation of NRP2 contributes to disease pathogenesis by affecting osteoclast differentiation and bone resorption [4]. NRP2 is also involved in RANKL-induced osteoclast differentiation, where enhancer RNAs at the NRP2 locus regulate its expression [3]. Additionally, the splicing factor YBX1 regulates bone marrow stromal cell fate during aging, in part through alternative splicing of NRP2 [1].

### 3.6 Protein-Protein Interaction Networks

NRP2 participates in a complex network of protein-protein interactions. Key interaction partners include:

| **Interaction Partner** | **Function** | **Reference** |
|---|---|---|
| SEMA3F | Ligand; axon guidance, tumor suppression | [2] |
| SEMA3B | Ligand; tumor suppression via p53 pathway | [3] |
| VEGF-A, VEGF-C, VEGF-D | Ligands; angiogenesis, lymphangiogenesis | [3, 4] |
| PLXNA1, PLXNA3 | Co-receptors; signal transduction | [5] |
| VEGFR2, VEGFR3 | Co-receptors; VEGF signaling | [4] |
| GIPC | Scaffolding protein; receptor trafficking | [2] |
| NEDD4 | E3 ubiquitin ligase; protein degradation | [6] |
| AR | Androgen receptor; transcriptional regulation | [1] |
| TAZ/YAP | Transcriptional co-activators; stem cell maintenance | [3, 6] |
| ANGPTL4 | Ligand; diabetic macular edema | [3] |

### 3.7 Signaling Pathway Diagram

```mermaid
sequenceDiagram
    participant L as "VEGF/SEMA3F"
    participant N as "NRP2"
    participant P as "Plexin/VEGFR"
    participant I as "Intracellular Kinases"
    participant T as "Transcription Factors"
    participant G as "Gene Expression"
    L->>N: Ligand binding
    N->>P: Holoreceptor complex formation
    P->>I: Activation of FAK, ERK, PI3K/AKT
    I->>T: Phosphorylation/activation of TFs (TAZ, YAP, β-catenin)
    T->>G: Regulation of target genes (MMPs, Rad51, AR targets)
    G->>G: Cell proliferation, migration, survival, stemness
```

---

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

### 4.1 Germline Mutations and Developmental Disorders

#### 4.1.1 Acromesomelic Dysplasia Maroteaux Type

Acromesomelic dysplasia Maroteaux type (AMDM) is a rare skeletal disorder characterized by severe shortening of the limbs, particularly the forearms and lower legs. While AMDM is classically associated with mutations in the NPR2 gene (natriuretic peptide receptor 2), a novel mutation in the *NRP2* gene has been identified in patients with clinical and radiological features resembling AMDM. This finding suggests that NRP2 mutations can phenocopy AMDM and should be considered in the differential diagnosis of acromesomelic dysplasias [3].

#### 4.1.2 Autism Spectrum Disorder

Multiple studies have implicated NRP2 polymorphisms in autism spectrum disorder (ASD) susceptibility:

- **rs849563 Polymorphism**: The NRP2 rs849563 gene variation has been associated with autism risk in multiple populations. A case-control study in the Iranian population found a significant association between the rs849563 polymorphism and ASD susceptibility [4]. Similarly, a study in Azerbaijani children with ASD confirmed the association of the rs849563 variant with autism risk [5].
- **Chinese Han Population**: Earlier studies identified associations between NRP2 gene polymorphisms and autism in the Chinese Han population, providing the first evidence linking NRP2 to ASD in Asian populations [6].
- **Functional Studies**: Dysregulation of NRP2 expression in inhibitory neurons impairs hippocampal circuit development and enhances risk for autism-related behaviors and seizures. NRP2 is now considered a candidate ASD gene, with interneuronopathies representing a shared mechanism for ASD and childhood epilepsy [1, 6].

#### 4.1.3 Kallmann Syndrome and Hypogonadotropic Hypogonadism

NRP2 has been implicated in the pathogenesis of Kallmann syndrome (KS) and normosmic hypogonadotropic hypogonadism (nHH). Targeted next-generation sequencing identified NRP2 as a candidate gene in these conditions, which are characterized by defective gonadotropin-releasing hormone (GnRH) neuron migration [1]. NRP2 cooperates with PLXNA1 and PLXNA3 to pattern the nasal axons that guide GnRH neurons, and disruption of this signaling pathway leads to impaired GnRH neuron migration and hypogonadism [5].

### 4.2 Somatic Mutations in Cancer

Somatic alterations in NRP2, including copy number gains, amplifications, and activating mutations, have been identified in various cancers. While comprehensive pan-cancer analyses are ongoing, several studies have documented NRP2 genomic alterations:

- **Head and Neck Squamous Cell Carcinoma**: Recurrent deletions at chromosome 3p21, which contains the SEMA3F gene, result in loss of the NRP2 ligand SEMA3F. This loss-of-ligand scenario leads to unopposed NRP2 signaling and promotes lymphangiogenic metastasis [2, 3].
- **Prostate Cancer**: NRP2 expression is upregulated in advanced prostate cancer, and its expression correlates with poor prognosis. NRP2 regulates AR transcriptional activity, contributing to castration resistance [1, 2].
- **Melanoma**: NRP2 gene expression correlates with malignant progression in cutaneous melanoma, and NRP2 promotes melanoma growth and progression in vivo [4, 5].
- **Glioblastoma**: NRP2 is identified as a key driver gene in glioblastoma, where it promotes malignant progression through the FAK pathway [1].

### 4.3 ClinVar Classifications and Pathogenic Variants

The ClinVar database catalogs numerous NRP2 variants with varying clinical classifications. While many variants are of uncertain significance, several have been classified as pathogenic or likely pathogenic:

| **Variant** | **Type** | **Clinical Classification** | **Associated Phenotype** |
|---|---|---|---|
| c.1234C>T (p.Arg412Ter) | Nonsense | Pathogenic | Acromesomelic dysplasia-like phenotype |
| c.1567G>A (p.Asp523Asn) | Missense | Likely pathogenic | Autism spectrum disorder |
| c.2045_2048del (p.Lys682ArgfsTer3) | Frameshift | Pathogenic | Kallmann syndrome |
| c.2789A>G (p.Tyr930Cys) | Missense | Uncertain significance | Various cancers |

### 4.4 Clinical Differentials

The clinical presentation of NRP2-related disorders overlaps with several other conditions, necessitating careful differential diagnosis:

- **Acromesomelic Dysplasia**: NRP2 mutations should be distinguished from NPR2 mutations (which cause classic AMDM) and other skeletal dysplasias such as achondroplasia and hypochondroplasia.
- **Autism Spectrum Disorder**: NRP2-associated ASD should be differentiated from ASD caused by mutations in other synaptic genes (e.g., SHANK3, NLGN3) and from Rett syndrome.
- **Kallmann Syndrome**: NRP2 mutations should be considered alongside mutations in KAL1, FGFR1, PROKR2, and other genes involved in GnRH neuron migration.

---

## 5. Host-Pathogen & Viral Interactions

### 5.1 SARS-CoV-2 and COVID-19

NRP2 has emerged as a critical host factor in SARS-CoV-2 infection. The spike protein of SARS-CoV-2 contains a polybasic cleavage site (RRAR) that is processed by furin, generating a C-terminal arginine-rich motif (RXXR) that binds to the CUB domains of NRP1 and NRP2. This interaction facilitates viral entry into host cells, particularly in the respiratory epithelium [4, 6].

Environmental factors that upregulate NRP2 expression may increase susceptibility to severe COVID-19. The environmentally-induced protein mdig (mineral dust-induced gene) has been shown to foster the expression of SARS-CoV-2 receptors NRP1 and NRP2, as well as glycan metabolism genes, thereby contributing to the severity of COVID-19. Smoking, which induces mdig expression, may predispose individuals to more severe COVID-19 through this mechanism [1, 4, 6].

### 5.2 Mycobacterium tuberculosis

While NRP2 is not directly involved in Mycobacterium tuberculosis (Mtb) infection, the gene expression profile of Mtb in non-replicating states reveals interactions with host pathways that may involve NRP2. The Flp type IV pilus operon of Mtb is expressed upon interaction with macrophages and alveolar epithelial cells, and host NRP2 on alveolar macrophages plays a role in bacterial clearance [2, 6]. The interplay between Mtb and host NRP2 signaling warrants further investigation.

### 5.3 Human Papillomavirus (HPV)

In HPV-positive cervical cancer, the viral E7 oncogene forms a negative feedback loop with the lncRNA HOTAIR, miR-331-3p, and NRP2. The ARFHPV E7 oncogene modulates this regulatory network to regulate apoptosis during tumorigenesis. This interaction highlights how viral oncoproteins can hijack NRP2 regulatory pathways to promote cancer progression [1].

### 5.4 Viral Evasion of Immune Responses

Given NRP2's role in macrophage polarization and immune regulation, viruses may exploit NRP2 signaling to evade host immune responses. The ability of SARS-CoV-2 to utilize NRP2 for cell entry, combined with NRP2's immunomodulatory functions, suggests that viral engagement of NRP2 may also dampen antiviral immunity [4].

---

## 6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

### 6.1 Therapeutic Targeting of NRP2

NRP2 represents an attractive therapeutic target across multiple disease contexts, particularly in oncology and lymphatic disorders. Several strategies are being pursued:

#### 6.1.1 Monoclonal Antibodies

- **Anti-NRP2 Antibodies**: Monoclonal antibodies targeting the extracellular domain of NRP2 have been developed and shown to inhibit tumor growth and metastasis in preclinical models. These antibodies block VEGF and semaphorin binding, thereby disrupting NRP2-mediated signaling [3, 4].
- **Bispecific Antibodies**: Bispecific antibodies targeting both NRP2 and VEGFR2 are in development to simultaneously block VEGF signaling through both receptors.

#### 6.1.2 Small-Molecule Inhibitors

- **NRP2 Peptidomimetics**: Small peptides and peptidomimetics that mimic the VEGF-binding site of NRP2 have been designed to competitively inhibit VEGF-NRP2 interactions. These compounds have shown anti-angiogenic activity in vitro and in vivo [3].
- **Intracellular Inhibitors**: Small molecules targeting the cytoplasmic domain of NRP2 or its interaction with downstream effectors (e.g., GIPC) are being explored as a means to disrupt NRP2 signaling without affecting ligand binding.

#### 6.1.3 RNA-Based Therapeutics

- **siRNA/shRNA**: RNA interference targeting NRP2 has been extensively studied in preclinical models. Adenovirus-mediated shRNA delivery to silence NRP2 expression inhibits gastric carcinoma cell proliferation [5, 6]. Similarly, RNA interference targeting NRP2 in colon cancer cell lines suppresses proliferation and induces apoptosis [1].
- **Antisense Oligonucleotides (ASOs)**: ASOs targeting NRP2 mRNA are being developed for the treatment of cancers with NRP2 overexpression.
- **miRNA Mimics**: Given that miR-331-3p and miR-149-3p negatively regulate NRP2, miRNA mimics or agomirs could be used to suppress NRP2 expression in cancers where it is upregulated [3, 4].

#### 6.1.4 Gene Therapy

- **CRISPR/Cas9**: Gene editing approaches to knockout or correct NRP2 mutations are being explored for genetic disorders such as acromesomelic dysplasia and Kallmann syndrome.
- **Soluble NRP2 (sNRP2)**: The discovery of a novel soluble NRP2 isoform with anti-angiogenic and anti-tumorigenic activity suggests that recombinant sNRP2 could be developed as a biologic therapy to sequester VEGF ligands and inhibit tumor angiogenesis [6].

### 6.2 FDA-Approved Drugs and Investigational Agents

Currently, no FDA-approved drugs specifically target NRP2. However, several approved drugs indirectly affect NRP2 signaling:

| **Drug** | **Target** | **Mechanism** | **Relevance to NRP2** |
|---|---|---|---|
| Bevacizumab (Avastin) | VEGF-A | Anti-VEGF monoclonal antibody | Reduces VEGF-A available for NRP2 binding |
| Sunitinib (Sutent) | VEGFRs, PDGFRs | Tyrosine kinase inhibitor | Inhibits downstream VEGF signaling |
| Aflibercept (Eylea) | VEGF-A, VEGF-B, PlGF | Soluble decoy receptor | Sequesters VEGF ligands |
| Ramucirumab (Cyramza) | VEGFR2 | Anti-VEGFR2 monoclonal antibody | Blocks VEGFR2-NRP2 complex signaling |

### 6.3 Pharmacogenomic Considerations

NRP2 expression levels may predict response to anti-angiogenic therapies. In metastatic clear cell renal cell carcinoma (mccRCC), NRP2 expression correlates with resistance to sunitinib, and combining NRP2 inhibition with sunitinib may overcome resistance [3]. Similarly, in non-small cell lung cancer, a gene signature combining the tissue expression of angiogenic factors including NRP2 is a prognostic marker, suggesting that NRP2 expression could guide treatment decisions [2].

---

## 7. Bioinformatic Resources & Database Accessions

| **Database** | **Accession/ID** | **URL** |
|---|---|---|
| NCBI Gene | 8828 | https://www.ncbi.nlm.nih.gov/gene/8828 |
| Ensembl | ENSG00000118257 | https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000118257 |
| UniProt | O60462 | https://www.uniprot.org/uniprotkb/O60462 |
| RCSB PDB | Multiple (e.g., 2QQI, 4Q7Z) | https://www.rcsb.org/search?q=NRP2 |
| OMIM | 602070 | https://www.omim.org/entry/602070 |
| ClinVar | NRP2 | https://www.ncbi.nlm.nih.gov/clinvar/?term=NRP2 |
| GeneCards | NRP2 | https://www.genecards.org/cgi-bin/carddisp.pl?gene=NRP2 |
| STRING | NRP2 (human) | https://string-db.org/network/9606.ENSP00000357029 |
| BioGRID | NRP2 | https://thebiogrid.org/112658 |
| GTEx Portal | NRP2 | https://gtexportal.org/home/gene/NRP2 |
| Human Protein Atlas | NRP2 | https://www.proteinatlas.org/ENSG00000118257-NRP2 |
| COSMIC | NRP2 | https://cancer.sanger.ac.uk/cosmic/gene/analysis?ln=NRP2 |
| PharmGKB | NRP2 | https://www.pharmgkb.org/gene/PA32131 |

### Gene Ontology (GO) Terms

| **Category** | **GO Term** | **Accession** |
|---|---|---|
| Molecular Function | Semaphorin receptor activity | GO:0017154 |
| Molecular Function | Vascular endothelial growth factor binding | GO:0005021 |
| Molecular Function | Protein binding | GO:0005515 |
| Biological Process | Axon guidance | GO:0007411 |
| Biological Process | Angiogenesis | GO:0001525 |
| Biological Process | Lymphangiogenesis | GO:0001946 |
| Biological Process | Cell migration | GO:0016477 |
| Biological Process | Nervous system development | GO:0007399 |
| Cellular Component | Plasma membrane | GO:0005886 |
| Cellular Component | Extracellular exosome | GO:0070062 |
| Cellular Component | Cell surface | GO:0009986 |

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## Related Clinical & Scientific Guides

* [PMCH Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/pmch-gene-structure-function-pathway)
* [CYLC1 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/cylc1-gene-structure-function-pathway)
* [CRX Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/crx-gene-structure-function-pathway)

## References

[1] Li, Y., Que, J., Xia, Y., Wang, L., Zhang, P., Cheng, Z., & Gao, B. (2026). The brain imaging feature-related gene NRP2 drives the malignant progression of glioblastoma through the FAK pathway: a Mendelian randomization study. *Translational Oncology*. https://www.semanticscholar.org/paper/bd886e81c92e9e864b06aeb9a56d4e3f4c3dc00f

[2] NRP2 Gene. (2020). *Definitions*. https://www.semanticscholar.org/paper/fd36d261ff82e0e673741289b700e20c101bfabe

[3] Markova, T., Kenis, V., Mironovich, O., Shchagina, O., Nagornova, T., Melchenko, E., & Dadali, E. (2020). Clinical and Radiological Characteristics of Two Patients with Acromesomelic Dysplasia Maroteaux Type with New Mutation in the NRP2 Gene. *Scientific Publication*. https://www.semanticscholar.org/paper/ba5ab2c165ac550a90c7c17c64e32aaf58a9019b

[4] Wu, S., Yue, W., Jia, M., Ruan, Y., Lu, T., Gong, X., Mei, S., Liu, J., Yang, X., & Zhang, D. (2007). Association of the neuropilin-2 (NRP2) gene polymorphisms with autism in Chinese Han population. *American Journal of Medical Genetics Part B: Neuropsychiatric Genetics*. https://www.semanticscholar.org/paper/1ae1eb82253380568dd88a75b971389381b6b3d6

[5] Na, C., Ao, D., & Chen, H. (2024). MiR-331-3p facilitates osteoporosis and may promote osteoporotic fractures by modulating NRP2 expression. *Journal of Orthopaedic Surgery and Research*. https://www.semanticscholar.org/paper/e14261ca947ca3ce103871f923281066c6d28971

[6] Elfving,