# LECT2 Gene: Structure, Function, and Clinical Significance


## Key Takeaways

- The *LECT2* gene encodes a secreted protein with a C-type lectin-like fold, crucial for liver regeneration, metabolic homeostasis, and tumor suppression, primarily through interaction with the MET receptor tyrosine kinase.
- A common polymorphism, p.Ile40Val (I40V), is a significant risk factor for ALECT2 amyloidosis, a systemic disease characterized by amyloid fibril deposition in organs like the kidney and liver, particularly in homozygous individuals.
- In hepatocellular carcinoma (HCC), *LECT2* is frequently silenced via promoter hypermethylation and copy number loss, leading to unchecked MET signaling and promoting tumor progression.
- LECT2 acts as a hepatokine that exacerbates insulin resistance by activating the JNK pathway in skeletal muscle and inhibits AMPK activity, contributing to metabolic dysfunction-associated steatohepatitis (MASH).
- Therapeutic strategies are being developed to target LECT2, including anti-amyloid antibodies and protein stabilizers for ALECT2 amyloidosis, and recombinant protein administration or demethylating agents to restore its tumor-suppressive function in HCC.

---

## Executive Summary & Key Metadata

Leukocyte cell-derived chemotaxin 2 (LECT2) is a secreted, multifunctional protein encoded by the *LECT2* gene. Initially identified in 1996 as a chemotactic factor for neutrophils, LECT2 has since been implicated in a broad spectrum of biological processes, including liver regeneration, metabolic homeostasis, amyloidosis, and tumor suppression. Its clinical relevance spans from a causative agent in systemic amyloidosis to a potential biomarker and therapeutic target in hepatocellular carcinoma and metabolic dysfunction-associated steatohepatitis (MASH). This reference manual provides a comprehensive analysis of the *LECT2* gene, covering its genomic architecture, protein structure, signaling pathways, pathogenic mutations, and pharmacogenomic implications.

| **Attribute** | **Detail** |
| :--- | :--- |
| **HGNC Symbol** | LECT2 |
| **UniProt Accession** | O14960 |
| **Representative PDB ID** | True (e.g., 5B0H, 5B0G) |
| **Chromosomal Locus** | 5q31.2 |
| **Primary Molecular Function** | Secreted cytokine/chemokine; involved in cell growth, migration, and metabolic regulation |
| **Disease & Pathology Associations** | Amyloidosis (ALECT2), Hepatocellular Carcinoma (HCC), MASH, Sepsis, Rheumatoid Arthritis |

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Chromosomal Localization and Gene Structure

The *LECT2* gene is located on the long (q) arm of chromosome 5 at band 31.2 (5q31.2). This region is a gene-dense area known to harbor several cytokine genes, including those for interleukins (IL-4, IL-5, IL-13) and the *IRF1* gene, placing *LECT2* within a critical immunoregulatory cluster. The precise genomic coordinates (GRCh38/hg38) are approximately chr5:135,474,472-135,484,110 (minus strand). The gene spans roughly 9.6 kilobases (kb) of genomic DNA.

The gene consists of four exons and three introns. The coding sequence (CDS) is relatively compact, with the open reading frame (ORF) spanning from exon 1 through exon 4. The exon-intron boundaries conform to the canonical GT-AG splice donor and acceptor consensus sequences.

- **Exon 1:** Contains the 5' untranslated region (UTR) and the start codon (ATG). It encodes the N-terminal signal peptide, which directs the nascent polypeptide into the endoplasmic reticulum (ER) for secretion.
- **Exon 2:** Encodes a portion of the mature protein, including a region critical for dimerization.
- **Exon 3:** The largest exon, encoding the central core of the protein, which contains the majority of the β-strands that form the β-sandwich structure.
- **Exon 4:** Contains the 3' end of the CDS and a long 3' UTR. The 3' UTR is notable for containing multiple AU-rich elements (AREs), which are known to regulate mRNA stability and translation in response to cellular signals.

### 1.2 Promoter Architecture and Transcriptional Regulation

The promoter region of *LECT2* lacks a canonical TATA box but contains a high GC content, characteristic of housekeeping and growth-related genes. Several cis-acting regulatory elements have been identified *in silico* and experimentally validated:

- **Hepatocyte Nuclear Factor 1 (HNF-1) and HNF-4α Binding Sites:** These are the primary drivers of *LECT2* transcription in hepatocytes. HNF-4α is a master regulator of hepatocyte differentiation and metabolism, and its binding to the *LECT2* promoter is essential for high-level hepatic expression.
- **CCAAT/Enhancer-Binding Protein (C/EBP) Sites:** C/EBPα and C/EBPβ bind to the promoter and synergize with HNF factors to modulate transcription, particularly during the acute-phase response and liver regeneration.
- **Signal Transducer and Activator of Transcription 3 (STAT3) Response Elements:** The presence of STAT3 binding sites links *LECT2* expression to IL-6 family cytokine signaling. This is particularly relevant in the context of inflammation and liver injury, where IL-6 is a primary driver of the acute-phase response.
- **Hypoxia-Responsive Elements (HREs):** Putative binding sites for Hypoxia-Inducible Factor 1-alpha (HIF-1α) exist in the promoter, suggesting a mechanism for the observed upregulation of LECT2 in ischemic conditions.

### 1.3 Enhancer Elements and Chromatin State

Chromatin immunoprecipitation sequencing (ChIP-seq) data from the ENCODE project reveals that the *LECT2* locus is marked by H3K27ac (acetylation of histone H3 at lysine 27) and H3K4me1 (monomethylation of histone H3 at lysine 4) in hepatic cell lines (e.g., HepG2), indicating an active enhancer and promoter state. A putative enhancer element is located approximately 5 kb upstream of the transcription start site (TSS). This enhancer region is bound by HNF-4α and forms a chromatin loop with the promoter to drive robust expression. In non-hepatic tissues, this enhancer is in a repressed state, marked by H3K27me3 (trimethylation of histone H3 at lysine 27), which explains the relatively restricted expression pattern of LECT2.

### 1.4 Alternative Splicing and Isoforms

The primary transcript of *LECT2* undergoes alternative splicing, generating two main mRNA isoforms:

1.  **Isoform 1 (Canonical):** This is the full-length transcript containing all four exons. It encodes the 151-amino acid precursor protein (including the 18-amino acid signal peptide). The mature, secreted protein is 133 amino acids long. This is the predominant and biologically active isoform.
2.  **Isoform 2:** This variant arises from the retention of intron 2. This retention introduces a premature stop codon, leading to a truncated, non-secreted protein. The functional significance of this isoform is unclear, but it may act as a dominant-negative regulator or be subject to nonsense-mediated mRNA decay (NMD). Its expression is typically low and may be tissue-specific.

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

### 2.1 Primary Structure and Post-Translational Modifications

The *LECT2* gene encodes a precursor protein of 151 amino acids. The N-terminal 18 amino acids constitute a hydrophobic signal peptide that is cleaved upon translocation into the ER. The resulting mature protein (133 amino acids, ~16 kDa) is secreted as a homodimer.

The primary sequence contains several notable features:
- **Cysteine Residues:** The mature protein contains four cysteine residues (Cys19, Cys31, Cys98, and Cys111 in the mature peptide numbering). These form two intramolecular disulfide bonds (Cys19-Cys31 and Cys98-Cys111), which are critical for stabilizing the tertiary structure. The dimer is held together by non-covalent hydrophobic interactions, not by an intermolecular disulfide bond.
- **Glycosylation Sites:** While LECT2 is not heavily glycosylated, there is a predicted N-linked glycosylation site (Asn-X-Ser/Thr) at Asn89. However, the occupancy of this site appears to be low and may be cell-type specific. The functional role of this potential glycosylation is not fully defined.

### 2.2 Secondary and Tertiary Structure

The three-dimensional structure of human LECT2 has been solved by X-ray crystallography (PDB entries 5B0H and 5B0G). The structure reveals that LECT2 adopts a **β-sandwich fold** that is structurally homologous to the C-type lectin domain (CTLD) superfamily, despite lacking the canonical calcium-binding motifs (EPN and WND) found in classical C-type lectins.

The β-sandwich is composed of two antiparallel β-sheets:
- **Sheet 1 (Concave):** Comprised of β-strands β1, β4, β5, and β8.
- **Sheet 2 (Convex):** Comprised of β-strands β2, β3, β6, and β7.

The two sheets are connected by loop regions and the two intramolecular disulfide bonds. The overall topology creates a stable, globular structure. A long loop between β-strands β2 and β3 forms a prominent structural feature that is involved in dimerization.

### 2.3 Quaternary Structure and Dimerization Interface

LECT2 exists as a non-covalent homodimer in solution and in the crystal structure. The dimerization interface is extensive and buries a significant solvent-accessible surface area. The interface is formed primarily by hydrophobic interactions between residues from the β2-β3 loop and the β7 strand of each monomer. This head-to-head arrangement creates a symmetric dimer with two potential ligand-binding sites located at the distal ends of the molecule.

The dimeric state is essential for the biological activity of LECT2. Mutations that disrupt the dimerization interface result in a loss of function, likely due to reduced stability and an inability to engage its receptors.

### 2.4 Ligand Binding Pockets and Functional Surfaces

While the exact ligand for LECT2 remains an area of active investigation, structural studies and mutagenesis have identified a putative binding pocket. This pocket is located on the concave face of the β-sandwich, a common feature in C-type lectin-like domains. This region is rich in charged and aromatic residues, suggesting it may interact with a protein ligand or a carbohydrate moiety.

Recent evidence points to the receptor tyrosine kinase **MET** (hepatocyte growth factor receptor) as a key binding partner for LECT2. The interaction is believed to occur between the LECT2 dimer and the SEMA domain of MET. This interaction inhibits MET's activation by its canonical ligand, HGF, thereby suppressing downstream signaling.

> **Interactive 3D Protein Visualizer: Load LECT2 (PDB: true)**
> [Interactive 3D Protein Visualizer: Load LECT2 (PDB: true)](/tools/protein-structure-viewer?source=alphafold&accession=O14960)
>
> *Use the visualizer to explore the β-sandwich architecture, the disulfide bonds, and the dimerization interface of LECT2. The structure is based on the X-ray crystal structure (PDB: 5B0H).*

## 3. Cellular Signaling Pathways & Molecular Function

LECT2 is a secreted protein that functions in an autocrine, paracrine, and endocrine manner. Its primary site of synthesis is the liver, from where it is secreted into the bloodstream. Its functions are context-dependent, ranging from a chemotactic factor to a metabolic regulator and a tumor suppressor.

### 3.1 The LECT2-MET Signaling Axis

The most well-characterized signaling pathway for LECT2 is its inhibitory action on the MET receptor tyrosine kinase.

1.  **Ligand Binding:** LECT2 is secreted by hepatocytes and binds directly to the SEMA domain of the MET receptor on the surface of target cells (e.g., hepatocytes, cancer cells).
2.  **Receptor Antagonism:** By binding to MET, LECT2 sterically hinders the binding of Hepatocyte Growth Factor (HGF). This prevents HGF-induced MET dimerization and autophosphorylation of key tyrosine residues (Tyr1234 and Tyr1235) in the kinase domain.
3.  **Downstream Signaling Inhibition:** The lack of MET phosphorylation prevents the recruitment of adaptor proteins such as GRB2 and GAB1. This, in turn, inhibits the activation of downstream signaling cascades, including:
    - **PI3K-AKT Pathway:** Reduced AKT phosphorylation leads to decreased cell survival and proliferation.
    - **RAS-MAPK Pathway:** Reduced ERK1/2 phosphorylation leads to decreased cell proliferation and migration.
4.  **Biological Consequence:** In the context of the liver, this pathway is critical for maintaining homeostasis. LECT2 acts as a "brake" on hepatocyte proliferation. During liver regeneration, LECT2 expression is downregulated to allow HGF-driven proliferation to proceed. In hepatocellular carcinoma (HCC), LECT2 expression is often silenced, leading to unchecked MET signaling and tumor progression.

### 3.2 Role in Innate Immunity and Chemotaxis

LECT2 was originally identified as a chemotactic factor for neutrophils. It is secreted at sites of inflammation and promotes the directed migration of neutrophils via a pertussis toxin-sensitive G-protein-coupled receptor (GPCR). The precise identity of this GPCR is still under investigation, but it is distinct from the MET receptor.

- **Neutrophil Migration:** LECT2 induces actin polymerization and polarization in neutrophils, facilitating their extravasation from the bloodstream into tissues.
- **Macrophage Modulation:** LECT2 can also modulate macrophage function. It has been shown to promote the phagocytic activity of macrophages and influence their polarization state, shifting them from a pro-inflammatory (M1) to an anti-inflammatory (M2) phenotype in certain contexts.

### 3.3 Regulation of Metabolic Homeostasis

LECT2 is a hepatokine that links liver metabolism to whole-body energy balance.

- **Insulin Resistance:** LECT2 expression is upregulated in the livers of obese individuals and in mouse models of diet-induced obesity. Elevated circulating LECT2 levels are associated with insulin resistance in skeletal muscle. Mechanistically, LECT2 activates the JNK (c-Jun N-terminal kinase) pathway in muscle cells, leading to inhibitory phosphorylation of IRS-1 (Insulin Receptor Substrate 1) at Ser307. This impairs insulin signaling and glucose uptake.
- **AMPK Inhibition:** LECT2 has also been shown to inhibit AMP-activated protein kinase (AMPK) activity in muscle and adipose tissue. AMPK is a master regulator of energy homeostasis, and its inhibition by LECT2 contributes to reduced fatty acid oxidation and mitochondrial dysfunction.
- **MASH Progression:** In the context of metabolic dysfunction-associated steatohepatitis (MASH), LECT2 is upregulated. It promotes hepatic inflammation and fibrosis by activating hepatic stellate cells, contributing to the progression from simple steatosis to NASH.

### 3.4 Protein-Protein Interaction Networks

The LECT2 interactome is still being mapped, but key interactions have been identified:

- **MET:** The primary receptor mediating its tumor-suppressive and anti-proliferative effects.
- **Annexin A2 (ANXA2):** LECT2 has been shown to bind to ANXA2 on the surface of endothelial cells. This interaction may be involved in LECT2's pro-angiogenic or anti-angiogenic effects, which appear to be context-dependent.
- **CD209 (DC-SIGN):** LECT2 can bind to the C-type lectin receptor DC-SIGN on dendritic cells. This interaction may modulate immune responses.
- **Extracellular Matrix Components:** LECT2 has been reported to bind to components of the extracellular matrix, such as fibronectin, which may localize it within tissues and facilitate its paracrine functions.

```mermaid
sequenceDiagram
    participant H as "Hepatocyte"
    participant L as "LECT2 (Secreted)"
    participant M as "MET Receptor"
    participant C as "Cancer Cell (HCC)"
    participant I as "Insulin Signaling (Muscle)"
    H->>L: Secretes LECT2
    L->>M: Binds to SEMA domain of MET
    M-->>M: Blocks HGF binding & Autophosphorylation
    M-->>C: Inhibits PI3K/AKT & RAS/MAPK pathways
    Note over C: Reduced Proliferation & Migration<br/>(Tumor Suppression)

    H->>L: High Secretion (in Obesity)
    L->>I: Activates JNK pathway
    I-->>I: Phosphorylates IRS-1 (Ser307)
    Note over I: Impaired Glucose Uptake<br/>(Insulin Resistance)
```

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

Mutations in the *LECT2* gene are primarily associated with a specific form of systemic amyloidosis, known as ALECT2 amyloidosis. Unlike many other amyloidoses, ALECT2 is not caused by a single highly penetrant pathogenic mutation but is strongly linked to a specific polymorphism in the general population.

### 4.1 The p.Ile40Val (I40V) Polymorphism and ALECT2 Amyloidosis

The most significant genetic variant in *LECT2* is a single nucleotide polymorphism (SNP) that results in an amino acid substitution at position 40 of the mature protein (isoleucine to valine, I40V). This variant is extremely common, with a minor allele frequency (MAF) of approximately 20-30% in populations of East Asian, Hispanic, and Middle Eastern descent. It is this variant, specifically the homozygous state (Val40/Val40), that is found in the vast majority of patients with ALECT2 amyloidosis.

- **Mechanism of Amyloidogenesis:** The I40V substitution is located in a critical region of the β-sandwich structure. It is believed to decrease the thermodynamic stability of the protein, increasing its propensity to misfold. Under certain conditions, the misfolded protein aggregates into amyloid fibrils, which deposit in tissues, particularly the kidneys and liver.
- **Clinical Presentation:** ALECT2 amyloidosis typically presents in older adults (usually >60 years) with chronic kidney disease and proteinuria. It is a slowly progressive disease. Hepatic involvement is common but often asymptomatic, presenting with elevated alkaline phosphatase. It is now recognized as one of the most common causes of renal amyloidosis worldwide, particularly in Hispanic and South Asian populations.
- **Genetic Risk:** The risk of developing ALECT2 is strongly associated with the *homozygous* Val40 genotype. Heterozygotes (Ile40/Val40) are at significantly lower risk, suggesting a recessive mode of inheritance for the disease susceptibility.

### 4.2 Other Reported Variants and Their Pathogenicity

While the I40V variant is the primary driver of ALECT2, other rare variants have been reported in ClinVar and the literature. Their clinical significance is often less clear.

| **Variant (Protein)** | **Variant (cDNA)** | **ClinVar Classification** | **Phenotype** |
| :--- | :--- | :--- | :--- |
| p.Ile40Val | c.118A>G | Risk Factor | ALECT2 Amyloidosis |
| p.Arg72Cys | c.214C>T | Uncertain Significance | Potential altered protein stability |
| p.Gly111Arg | c.331G>A | Uncertain Significance | Reported in a case of hepatic amyloidosis |
| p.Val128Ile | c.382G>A | Benign/Likely Benign | No known phenotype |

### 4.3 LECT2 in Cancer: Somatic Alterations and Epigenetic Silencing

In the context of cancer, particularly hepatocellular carcinoma (HCC), the *LECT2* gene is frequently silenced, but this is primarily due to epigenetic mechanisms rather than somatic mutations.

- **Promoter Hypermethylation:** The *LECT2* promoter contains a CpG island. In HCC, this island is often hypermethylated, leading to transcriptional silencing and loss of LECT2 protein expression. This loss of expression removes the "brake" on MET signaling, contributing to tumor cell proliferation, invasion, and metastasis.
- **Copy Number Loss:** Loss of heterozygosity (LOH) at the 5q31.2 locus is a frequent event in HCC, leading to the deletion of one copy of the *LECT2* gene. Combined with promoter methylation of the remaining allele, this results in a complete loss of LECT2 expression.
- **Somatic Mutations:** While not a common mutational target, somatic missense mutations in *LECT2* have been identified in some cancer genome sequencing efforts (e.g., TCGA). The functional impact of these sporadic mutations is largely unknown, but they may contribute to a loss of function in a minority of cases.

### 4.4 Clinical Differentials and Diagnostic Considerations

The clinical presentation of ALECT2 amyloidosis (renal insufficiency, proteinuria) overlaps with other forms of amyloidosis (e.g., AL, AA, ATTR) and other causes of chronic kidney disease. The diagnosis requires a tissue biopsy, typically of the kidney or liver, with Congo red staining showing apple-green birefringence under polarized light. Mass spectrometry-based proteomic analysis of the amyloid deposits is the gold standard for identifying the specific precursor protein, confirming the diagnosis of ALECT2. Genetic testing for the I40V variant can support the diagnosis but is not definitive on its own, given the high frequency of the variant in the general population.

## 5. Host-Pathogen & Viral Interactions

The role of LECT2 in host-pathogen interactions is an emerging area of research. Its function as a chemotactic factor and immune modulator places it at the interface of the host response to infection.

### 5.1 Bacterial Infections and Sepsis

LECT2 is an acute-phase protein, and its serum levels change during bacterial infections.

- **Upregulation in Sepsis:** Studies have shown that LECT2 expression is significantly upregulated in the liver during sepsis. This is likely driven by pro-inflammatory cytokines such as IL-6 and TNF-α.
- **Modulation of the Innate Immune Response:** LECT2 can influence the host's ability to clear bacterial infections. It promotes the recruitment of neutrophils to the site of infection, enhancing bacterial clearance. However, in severe sepsis, excessive LECT2-driven inflammation can contribute to tissue damage and organ failure.
- **Interaction with Bacterial Toxins:** There is preliminary evidence suggesting that LECT2 may bind to certain bacterial components, such as lipopolysaccharide (LPS), potentially modulating its inflammatory effects. However, this interaction requires further validation.

### 5.2 Viral Infections

The role of LECT2 in viral infections is less well-defined but is an area of active investigation.

- **Hepatitis Viruses:** Given its high expression in the liver, LECT2 may play a role in the pathogenesis of viral hepatitis (HBV, HCV). Chronic viral hepatitis is a major risk factor for HCC, and the silencing of LECT2 in this context may contribute to the progression from chronic inflammation to cancer.
- **SARS-CoV-2:** A study investigating the host response to SARS-CoV-2 infection identified LECT2 as one of the downregulated genes in the liver of infected patients. The functional consequence of this downregulation is unknown, but it may contribute to the coagulopathy and systemic inflammation seen in severe COVID-19.
- **Influenza Virus:** LECT2 has been shown to have an inhibitory effect on influenza A virus replication *in vitro*. The proposed mechanism involves LECT2 binding to the viral hemagglutinin and preventing viral entry into host cells. This suggests a potential antiviral role for LECT2, but this has not been confirmed *in vivo*.

### 5.3 Parasitic Infections

LECT2 has been implicated in the immune response to parasitic infections, particularly those that involve the liver.

- **Malaria:** In a mouse model of cerebral malaria, LECT2 was found to be upregulated. It was shown to modulate the CD8+ T cell response, potentially influencing the development of cerebral pathology. The exact mechanism is still under investigation.

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

The clinical significance of LECT2 makes it an attractive target for therapeutic intervention. Strategies are being developed to either inhibit its pathogenic functions (e.g., in amyloidosis and insulin resistance) or restore its protective functions (e.g., in HCC).

### 6.1 Targeting LECT2 in ALECT2 Amyloidosis

Currently, there is no specific therapy to halt or reverse ALECT2 amyloidosis. Treatment is supportive, focusing on managing kidney disease and its complications.

- **Anti-Amyloid Antibodies:** A major therapeutic strategy for other amyloidoses (e.g., AL) involves the use of monoclonal antibodies that target the amyloid fibrils and promote their clearance by phagocytes. This approach is being explored for ALECT2. Antibodies specifically recognizing the LECT2 amyloid fibril conformation could be developed to clear existing deposits.
- **Stabilizers of the Native State:** Small molecules that bind to the native, folded state of LECT2 and prevent its misfolding into amyloid fibrils are a promising therapeutic avenue. This "kinetic stabilization" approach has been successful for transthyretin (TTR) amyloidosis, where drugs like tafamidis bind to the TTR tetramer and prevent its dissociation and misfolding. A similar strategy could be applied to the LECT2 dimer, particularly targeting the region around the I40V mutation to increase its stability.
- **Gene Silencing (siRNA/ASO):** Given that ALECT2 is a disease of protein overexpression (the amyloid precursor is the normal protein, just prone to misfolding), reducing the production of LECT2 could be a viable strategy. Small interfering RNAs (siRNAs) or antisense oligonucleotides (ASOs) targeting *LECT2* mRNA could be used to reduce hepatic LECT2 synthesis, thereby reducing the supply of the amyloidogenic precursor protein. This approach is currently in clinical trials for other amyloidoses (e.g., patisiran for ATTR).

### 6.2 Targeting LECT2 in Hepatocellular Carcinoma (HCC)

In HCC, LECT2 functions as a tumor suppressor, and its expression is lost. Therefore, the therapeutic goal is to restore LECT2 function.

- **Recombinant LECT2 Protein:** Administration of recombinant human LECT2 protein could potentially restore its tumor-suppressive effects. By binding to MET, it could inhibit HGF-driven tumor growth and metastasis. This approach is in the preclinical stage of development.
- **Demethylating Agents:** Since *LECT2* is silenced by promoter hypermethylation in HCC, drugs that inhibit DNA methyltransferases (DNMT inhibitors), such as 5-azacitidine and decitabine, could be used to reactivate LECT2 expression. These drugs are already FDA-approved for the treatment of myelodysplastic syndromes and are being investigated in solid tumors, including HCC.
- **Combination Therapy:** Combining LECT2 restoration (e.g., via DNMT inhibitors) with MET inhibitors (e.g., cabozantinib) could provide a dual approach to block the MET signaling pathway in HCC.

### 6.3 Targeting LECT2 in Metabolic Disease

In obesity and type 2 diabetes, LECT2 is overexpressed and contributes to insulin resistance. In this context, inhibiting LECT2 function is the therapeutic goal.

- **Monoclonal Antibodies:** Neutralizing monoclonal antibodies against LECT2 could be developed to sequester circulating LECT2 and prevent it from binding to its receptors in skeletal muscle and adipose tissue. This would relieve the inhibition on insulin signaling and improve glucose uptake.
- **Small-Molecule Inhibitors:** Small molecules that block the interaction between LECT2 and its receptor (e.g., the MET SEMA domain) could be developed. These would act as antagonists, preventing LECT2 from activating the JNK pathway in muscle cells.

### 6.4 Pharmacogenomic Considerations

The I40V polymorphism in *LECT2* could have pharmacogenomic implications. For example, patients who are homozygous for the Val40 allele may have a higher baseline risk for ALECT2 amyloidosis. If a therapy aimed at stabilizing the LECT2 protein is developed, it may be more effective in patients with the less stable Val40 variant. Conversely, in the context of HCC, the genotype may influence the response to demethylating agents, although this is speculative.

## 7. Bioinformatic Resources & Database Accessions

The following table provides key database accessions and resources for the *LECT2* gene and protein.

| **Database** | **Identifier / Link** | **Description** |
| :--- | :--- | :--- |
| **HGNC** | [HGNC:6557](https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:6557) | Gene symbol and nomenclature |
| **NCBI Gene** | [Gene ID: 3950](https://www.ncbi.nlm.nih.gov/gene/3950) | Comprehensive gene information, genomic context, and links |
| **Ensembl** | [ENSG00000145850](https://www.ensembl.org/Homo_sapiens/Gene/Summary?db=core;g=ENSG00000145850) | Genome assembly, transcripts, and variation |
| **UniProt** | [O14960](https://www.uniprot.org/uniprotkb/O14960/entry) | Protein sequence, function, and post-translational modifications |
| **RCSB PDB** | [5B0H](https://www.rcsb.org/structure/5B0H), [5B0G](https://www.rcsb.org/structure/5B0G) | Experimentally determined 3D structures |
| **ClinVar** | [LECT2](https://www.ncbi.nlm.nih.gov/clinvar/?term=LECT2%5Bgene%5D) | Human variations and their clinical significance |
| **OMIM** | [602440](https://www.omim.org/entry/602440) | Mendelian inheritance and phenotype links |
| **STRING** | [LECT2 (O14960)](https://string-db.org/network/9606.ENSP00000274954) | Protein-protein interaction networks |
| **BioGRID** | [LECT2](https://thebiogrid.org/112669) | Physical and genetic interactions |
| **Gene Ontology (GO)** | [GO:0005615](https://www.ebi.ac.uk/QuickGO/term/GO:0005615) (extracellular space), [GO:0006955](https://www.ebi.ac.uk/QuickGO/term/GO:0006955) (immune response), [GO:0008284](https://www.ebi.ac.uk/QuickGO/term/GO:0008284) (negative regulation of cell population proliferation) | Functional annotations |
| **Human Protein Atlas** | [LECT2](https://www.proteinatlas.org/ENSG00000145850-LECT2) | Tissue and cell line expression data |

## Related Clinical & Scientific Guides

* [UTY Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/metabolic-pathways/uty-gene-structure-function-pathway)
* [ZBTB42 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/metabolic-pathways/zbtb42-gene-structure-function-pathway)
* [TTLL8 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/metabolic-pathways/ttll8-gene-structure-function-pathway)


## References

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2.  An, J., & Zhang, X. (2019). LECT2 is a novel regulator of the MET receptor tyrosine kinase. *Journal of Biological Chemistry*, 294(15), 5904-5915. [URL: https://doi.org/10.1074/jbc.RA118.006654]
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4.  Benson, M. D., James, S., Scott, K., Liepnieks, J. J., & Kluve-Beckerman, B. (2008). Leukocyte cell-derived chemotaxin 2 (LECT2) amyloidosis is a frequent cause of hepatic and renal amyloidosis. *Amyloid*, 15(2), 105-110. [URL: https://doi.org/10.1080/13506120802006029]
5.  Zheng, H., Miyakawa, T., Sawano, Y., Asano, A., Ando, K., Yamagoe, S., ... & Tanokura, M. (2016). Crystal structure of human leukocyte cell-derived chemotaxin 2 (LECT2) reveals a C-type lectin-like fold. *Journal of Biological Chemistry*, 291(17), 9078-9086. [URL: https://doi.org/10.1074/jbc.M115.709485]
6.  Slowik, V., Apte, U., & Jain, D. (2015). Leukocyte cell-derived chemotaxin-2 (LECT2) amyloidosis. *Journal of Clinical and Experimental Hepatology*, 5(4), 344-347. [URL: https://doi.org/10.1016/j.jceh.2015.10.001]
7.  Liao, Y., Chen, W., & Wang, X. (2020). The role of LECT2 in the pathogenesis of hepatocellular carcinoma. *Journal of Cancer*, 11(10), 2894-2901. [URL: https://doi.org/10.7150/jca.41452]
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