3BETAHSD/D3 Antibody
Description
Biochemical Role of 3β-HSD
3β-HSD exists as two isoforms encoded by distinct genes:
Both isoforms catalyze two reactions:
Key substrates:
| Substrate | Product | Physiological Role |
|---|---|---|
| Pregnenolone | Progesterone | Precursor for mineralocorticoids/glucocorticoids |
| DHEA | Androstenedione | Androgen synthesis |
| 17α-Pregnenolone | 17α-Progesterone | Cortisol precursor |
Genetic Disorders
Mutations in HSD3B2 cause congenital adrenal hyperplasia (CAH), characterized by:
Autoimmune Associations
Autoantibodies against 3β-HSD are linked to:
Methodological Advances
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Reporter assays: HEK293 cells expressing HSD3B2 convert pregnenolone/DHEA into progesterone/androstenedione, detectable via progesterone/androgen receptor luciferase systems .
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Clinical diagnostics: ACTH stimulation tests with hormone level measurements (Table 1) .
Table 1: Hormonal Profile in 3β-HSD Deficiency (n=3)
| Hormone | Baseline | Post-ACTH (60 min) |
|---|---|---|
| 17-OHP | ↑ 6.8 ng/mL | ↑ 12.1 ng/mL |
| DHEA | ↑ 18.7 ng/mL | ↑ 34.2 ng/mL |
| Cortisol | ↓ 2.1 µg/dL | ↔ 2.3 µg/dL |
Therapeutic and Diagnostic Relevance
Product Specs
Target Background
Q&A
Basic Research Questions
How to validate specificity of 3β-HSD/D3 antibodies in steroidogenesis studies?
Methodological Answer:
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Validation Steps:
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Western Blot (WB): Use tissues/cells with known 3β-HSD isoform expression (e.g., adrenal zona glomerulosa for HSD3B1, testis for HSD3B2) .
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Immunohistochemistry (IHC): Compare staining patterns with published adrenal/zona-specific expression (HSD3B1 in zona glomerulosa vs. HSD3B2 in zona fasciculata) .
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Knockdown/Overexpression Controls: Use siRNA or plasmid transfection to confirm antibody reactivity loss/gain in target cells .
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Critical Data Table:
| Antibody Target | Expected Tissue Localization | Validation Technique | Key Reference |
|---|---|---|---|
| HSD3B1 | Adrenal zona glomerulosa | IHC, WB (42 kDa band) | |
| HSD3B2 | Adrenal zona fasciculata | WB, FC (HeLa cells) |
What are standard protocols for quantifying 3β-HSD enzymatic activity using antibody-based assays?
Methodological Answer:
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Luciferase Reporter System: Co-transfect HEK293 cells with HSD3B2/D3 expression vectors and steroid-responsive reporters (e.g., PR/AR-responsive luciferase). Measure substrate conversion (e.g., DHEA → androstenedione) via luminescence .
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Key Parameters:
Advanced Research Questions
How to resolve contradictory data in 3β-HSD autoantibody detection across autoimmune studies?
Methodological Answer:
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Problem-Shooting Framework:
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Epitope Mapping: Use truncated HSD3B constructs (N-terminal vs. C-terminal) to identify autoantibody binding regions. 77% of autoantibodies target the C-terminal domain .
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Assay Specificity: Compare radioligand binding assays (35S-labeled HSD3B-luciferase fusion) vs. ELISA. The former shows higher specificity (12% vs. 0% in controls) .
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Data Interpretation Table:
| Autoantibody Target | Reactivity Rate (POF Patients) | Preferred Detection Method |
|---|---|---|
| C-terminal HSD3B | 77% | Radioligand binding assay |
| N-terminal HSD3B | 22% | Fragment-specific ELISA |
How to differentiate HSD3B1 vs. HSD3B2 isoforms in adrenal tumor studies?
Methodological Answer:
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Experimental Design:
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Isoform-Specific Antibodies: Use monoclonal antibodies validated against recombinant HSD3B1/HSD3B2 proteins. For example, HSD3B1 antibodies show exclusive zona glomerulosa reactivity, while HSD3B2 stains zona fasciculata .
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Clinical Correlation: In aldosterone-producing adenomas (APA), HSD3B2 is dominant, while idiopathic hyperaldosteronism (IHA) shows HSD3B1 hyperplasia .
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Key Findings:
| Condition | HSD3B1 Expression | HSD3B2 Expression | Diagnostic Utility |
|---|---|---|---|
| APA | Absent | Strong | Tumor vs. hyperplasia |
| IHA | Robust (ZG) | Reduced | ZG expansion marker |
How to analyze functional impacts of HSD3B2 mutations in congenital adrenal hyperplasia (CAH)?
Methodological Answer:
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Stepwise Approach:
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Mutant Transfection: Express HSD3B2 mutants (e.g., C72R, V225D) in HEK293 cells. Measure DHEA→androstenedione vs. pregnenolone→progesterone conversion rates .
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Phenotype Correlation: Link residual enzymatic activity (<50% for DHEA conversion) to salt-wasting (SW) severity. For example, V299I retains >50% activity and avoids SW .
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Mutation Impact Table:
| Mutation | Substrate Specificity Loss | Clinical Phenotype |
|---|---|---|
| C72R | DHEA, P5 | Ambiguous genitalia + SW |
| V299I | DHEA only | Ambiguous genitalia (no SW) |
