SERPIND1 Human
Description
Introduction to SERPIND1 Human
SERPIND1 (Serpin Family D Member 1), also known as Heparin Cofactor II, is a serine protease inhibitor encoded by the SERPIND1 gene located on chromosome 22q11.21 . It regulates thrombin activity by forming a covalent complex with the enzyme, a process enhanced by heparin or dermatan sulfate . While historically studied for its anticoagulant properties, recent research highlights its oncogenic role in cancers, particularly epithelial ovarian cancer (EOC), where it promotes tumor progression via the PI3K/AKT pathway .
Table 1: SERPIND1 Expression in Ovarian Tissues
Cell Line Expression
SERPIND1 is ubiquitously expressed in ovarian cancer cell lines, with highest levels in CAOV3 and OVCAR3 (adenocarcinomas) and lowest in ES-2 (clear-cell carcinoma) .
Pro-Tumorigenic Mechanisms
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Proliferation: SERPIND1 overexpression accelerates cell proliferation (MTT assay: 2.8x tumor weight increase in vivo) .
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Apoptosis Inhibition: Silencing SERPIND1 increases apoptosis (flow cytometry: 35% apoptotic rate in siRNA-treated CAOV3 vs. 12% controls) .
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Metastasis: Promotes peritoneal metastasis in nude mice (2.69x tumor volume increase) .
Table 2: Functional Impact of SERPIND1 Modulation in Ovarian Cancer Cells
| Parameter | Overexpression (ES-2) | Knockdown (CAOV3/OVCAR3) |
|---|---|---|
| Proliferation Rate | ↑ 1.5x | ↓ 60% |
| S-Phase Entry | ↑ 25% | ↓ 40% |
| Migration/Invasion | ↑ 2.1x | ↓ 55% |
| Data from siRNA/lentiviral transfection experiments . |
Epithelial–Mesenchymal Transition (EMT)
SERPIND1 downregulates E-cadherin and upregulates N-cadherin, Vimentin, MMP2, and MMP9 via PI3K/AKT signaling . Inhibition of PI3K (LY294002) reverses these effects, reducing migration and invasion by 50% .
Upstream Regulation
NF-κB1 binds to the SERPIND1 promoter at positions −258 to −248 and +131 to +141, directly regulating its transcription .
Preclinical Findings
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siRNA Targeting: SERPIND1 knockdown reduces tumor growth and metastasis in xenograft models .
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PI3K/AKT Inhibitors: LY294002 abrogates SERPIND1-driven EMT and proliferation .
Recombinant SERPIND1 in Research
Recombinant Human SERPIND1 (3198-PI, R&D Systems) exhibits thrombin-inhibitory activity (IC₅₀ = 6.25 nM) and is used to study heparin-enhanced anticoagulation .
Comparative Roles in Other Cancers
Product Specs
Serpin Peptidase Inhibitor, Clade D Member 1 (SERPIND1), also known as heparin cofactor II, is a protein that in humans is encoded by the SERPIND1 gene. This gene belongs to the serpin superfamily whose members are the most important inhibitors of serine proteases in human plasma. SERPIND1 is a potent inhibitor of thrombin, a key enzyme in the coagulation cascade. The inhibitory activity of SERPIND1 is significantly enhanced in the presence of glycosaminoglycans such as dermatan sulfate and heparin. SERPIND1 is primarily synthesized in the liver and circulates in the bloodstream. Mutations in this gene are associated with SERPIND1 deficiency, a rare bleeding disorder characterized by a reduced ability to control blood clotting.
Serpin Family D Member 1, Cysteine Proteinase Inhibitor Clade D Member 1, Serpin Peptidase Inhibitor Clade D Member 1, Protease Inhibitor Leuserpin-2, Serpin D1, HCF2, HLS2, Leuserpin 2, D22S673, THPH10, HC-II, HCII, HC2, LS2.
Q&A
Basic Research Questions
What experimental approaches are recommended for detecting SERPIND1 expression in human tissues?
SERPIND1 mRNA quantification requires standardized protocols to ensure reproducibility. The PrimePCR™ SYBR® Green assay (Bio-Rad) demonstrates reliable performance with 94% efficiency, R² = 0.9997, and 100% specificity for human SERPIND1 transcripts (ENST00000215727, ENST00000406799) . Key methodological considerations:
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Primer Design: Use intron-spanning primers (e.g., sequence: CATCAGCATGCTAATTGTGGTCCCACACAAGATGTCTGGGATGAAGACCCTCGA...) to avoid genomic DNA amplification .
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Validation: Include melt curve analysis (Tm = 84°C) and standard curves spanning 20–20 million template copies to confirm linearity .
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Controls: Universal human reference RNA and iScript™ cDNA synthesis kits minimize batch effects .
How does SERPIND1 interact with coagulation pathways in humans?
SERPIND1 encodes heparin cofactor II (HCII), a serine protease inhibitor that regulates thrombin activity in the presence of dermatan sulfate . Experimental validation involves:
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Functional Assays: Measure thrombin inhibition rates using chromogenic substrates (e.g., S-2238) with/without dermatan sulfate supplementation.
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Structural Studies: Compare HCII’s reactive center loop (RCL) conformation with antithrombin III via X-ray crystallography to identify heparin-binding domains .
What phenotypic associations are documented for SERPIND1 mutations?
Heparin cofactor II deficiency, linked to SERPIND1 loss-of-function mutations, manifests as thrombophilia. Key findings from clinical studies:
| Mutation Type | Phenotype | Incidence | Reference |
|---|---|---|---|
| c.859G>A (p.Ala287Thr) | Reduced HCII activity | 1:1,000 | |
| Exon 5 deletions | Severe thromboembolism | <1:10,000 |
Methodological Note: Genotype-phenotype correlations require linkage disequilibrium analysis in pedigrees and thrombin generation assays .
Advanced Research Questions
How do evolutionary differences between human and shark SERPIND1 homologs inform wound-healing research?
Comparative genomics reveals divergent roles:
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Exon Structure: Humans have 8 exons vs. 7 in sharks, with an additional splice site altering isoform expression .
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Functional Divergence: Shark SERPIND1 promotes rapid dermal repair, while the human homolog associates with metastatic pathways (e.g., PI4Kaa and Snap29 interactions) .
Experimental Design:
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Perform RNA-seq on shark vs. human fibroblasts under hypoxic conditions.
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Use CRISPR-Cas9 to swap exons between species and assess thrombin inhibition kinetics .
How can researchers reconcile contradictory data on SERPIND1’s role in metabolic disorders?
The Berne Amish study identified a SERPINE1 (PAI-1) null mutation linked to longevity and reduced diabetes risk , but SERPIND1’s metabolic role remains unclear. Resolution strategies:
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Cohort Stratification: Compare carriers of SERPIND1 mutations (e.g., rs1799889) against SERPINE1 variants in matched populations.
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Multi-Omics Integration: Combine GWAS data with plasma proteomics to distinguish HCII-specific effects from PAI-1 confounders .
| Parameter | SERPINE1 +/+ (n=127) | SERPINE1 +/- (n=43) | P |
|---|---|---|---|
| Fasting insulin (µIU/mL) | 4.9 (3.3–6.7) | 4.0 (2.9–5.1) | 0.04 |
| Diabetes prevalence | 7% | 0% | <0.01 |
What computational tools predict the functional impact of SERPIND1 variants?
While focuses on SERPINA1, analogous pipelines apply:
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VEP (Variant Effect Predictor): Annotates splice-site disruptions (e.g., c.699_700dupTA in SERPINE1 ).
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AlphaFold2: Models HCII structural perturbations caused by missense variants.
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Meta-SNP: Integrates SIFT, PolyPhen-2, and PANTHER scores to prioritize pathogenic mutations.
Validation Step: Cross-reference predictions with thrombin inhibition assays in HEK293T overexpression models .
How do SERPIND1 expression levels correlate with aging biomarkers?
The Amish study design provides a template:
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Telomere Length: qPCR/Southern blot revealed SERPINE1+/- carriers had 12% longer leukocyte telomeres than wild types (P < 0.001) .
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Composite Aging Scores: Combine pulse pressure, carotid IMT, and fasting insulin into standardized z-scores for multivariate analysis .
Statistical Note: Use SOLAR for heritability estimation and SAS for Cox proportional hazards modeling of lifespan data .
Methodological Recommendations Table
Ethical Considerations: Studies involving rare variants (e.g., Amish cohort ) require community engagement to address genetic privacy concerns.
Funding Priorities: NIH PAR-24-XXX emphasizes translational work bridging SERPIND1’s coagulation and metabolic roles.
Product Science Overview
The SERPIND1 gene encodes a plasma serine protease that functions primarily as a thrombin and chymotrypsin inhibitor . The protein is activated by heparin, dermatan sulfate, and glycosaminoglycans . Members of the serpin family have highly conserved secondary structures with a reactive center loop that interacts with the protease active site to inhibit protease activity .
SERPIND1 is known for its role as a thrombin inhibitor. In the presence of glycosaminoglycans like heparin or dermatan sulfate, Heparin Cofactor II (HC-II), which is encoded by the SERPIND1 gene, becomes the predominant thrombin inhibitor, replacing antithrombin III (AT-III) . This mechanism is essential for regulating blood coagulation and preventing excessive clot formation .
Human recombinant SERPIND1 is used in various research applications to study its role in blood coagulation and its potential therapeutic uses. Understanding the function and regulation of this protein can provide insights into developing treatments for coagulation disorders and other related conditions .
For more detailed information, you can refer to resources like GeneCards and the Early Detection Research Network.
