CAPNS1 Human
Description
Functional Roles in Calpain Activation
CAPNS1 is indispensable for the activity of calpain-1 and calpain-2, forming heterodimers with their large catalytic subunits . Key functions include:
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Regulatory Role: Stabilizes calpain structures and modulates protease activity in response to calcium influx .
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Cellular Processes: Influences apoptosis, adhesion, migration, and autophagy via substrate cleavage (e.g., α-spectrin, caspase-3) .
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Disease Links: Dysregulation is implicated in neurodegeneration, cancer metastasis, and pulmonary arterial hypertension .
Cancer Progression
CAPNS1 overexpression correlates with poor prognosis in renal cell carcinoma (RCC) and HER2⁺ breast cancer:
Neurological and Cardiovascular Disease
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Neurodegeneration: CAPNS1 mislocalization and hyperactivation drive Purkinje cell loss in Kctd7 knockout mice, reversible via calpain inhibition .
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Pulmonary Hypertension: Biallelic CAPNS1 loss-of-function variants cause severe pulmonary arterial hypertension .
Ubiquitination and Activity Modulation
KCTD7-Cullin-3 complexes mediate non-degradative ubiquitination of CAPNS1, restraining calpain activity :
| Regulatory Pathway | Effect on CAPNS1 | Disease Implication |
|---|---|---|
| KCTD7-mediated ubiquitination | Reduces calpain hyperactivation | Neuroprotection in KCTD7 deficiency |
| Loss of KCTD7 | Increased CAPNS1 autolysis and α-spectrin cleavage | Neurodegeneration, ataxia |
Therapeutic Strategies
Product Specs
Q&A
Here’s a structured collection of FAQs tailored for researchers investigating CAPNS1 in human systems, organized by research complexity and grounded in experimental methodology:
What experimental approaches are used to determine CAPNS1's role in calpain protease activation?
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Methodological answer:
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Knockout models: Generate CAPNS1 KO cell lines (e.g., CRISPR/Cas9) and measure calpain activity via fluorogenic substrates like Suc-LLVY-AMC. Compare wild-type vs. KO cells under stress conditions (e.g., serum starvation) .
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Co-immunoprecipitation (Co-IP): Validate physical interactions between CAPNS1 and calpain catalytic subunits (e.g., CAPN1/CAPN2) using antibodies targeting both subunits .
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Activity assays: Quantify calcium-dependent proteolysis of substrates (e.g., α-spectrin) in lysates from CAPNS1-deficient cells .
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How do researchers screen for pathogenic CAPNS1 variants in genetic studies?
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Methodological answer:
What are standard techniques to assess CAPNS1 expression in disease contexts?
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Methodological answer:
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Western blot: Use anti-CAPNS1 antibodies (e.g., monoclonal clones) to quantify protein levels in tissues or cell lines.
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qPCR: Design primers spanning exon-exon junctions to avoid genomic DNA amplification. Normalize to housekeeping genes (e.g., GAPDH) .
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IHC/IF: Localize CAPNS1 in clinical samples (e.g., breast cancer biopsies) using validated antibodies .
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How can contradictory findings about CAPNS1’s role in cancer progression be resolved?
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Methodological answer:
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Multi-omics integration: Combine RNA-seq (to identify CAPNS1-correlated pathways), phosphoproteomics (to map calpain substrates), and clinical metadata (e.g., tumor stage).
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Context-specific assays: Compare CAPNS1 function in in vitro models (e.g., 2D vs. 3D cultures) and in vivo xenografts under varying microenvironments .
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Data reconciliation: Use Mendelian randomization in biobanks to distinguish causal roles from passenger effects .
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What strategies are employed to study CAPNS1’s dynamic interactions with PI3K-Akt signaling?
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Methodological answer:
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AP-MS with SILAC labeling: Perform affinity purification mass spectrometry (AP-MS) in serum-starved vs. stimulated cells (e.g., NIH 3T3) using isotopically labeled amino acids for quantification .
Interaction Partner Log2 Fold Change (Stimulated/Starved) p-value CAPNS1 -1.45 0.010 PI3K subunits No change NS -
Pathway inhibition: Treat cells with PI3K inhibitors (e.g., LY294002) and measure CAPNS1-Akt colocalization via PLA (Proximity Ligation Assay) .
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How do researchers address tissue-specific effects of CAPNS1 loss?
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Methodological answer:
Case Study: CAPNS1’s Role in USP1 Stability
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Conflict: While CAPNS1 KO reduces USP1 levels in fibroblasts , some cancers show USP1 upregulation despite low CAPNS1.
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Resolution workflow:
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Contextualize cell type: Compare USP1 turnover rates in epithelial vs. mesenchymal cells using cycloheximide chase assays.
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Post-translational modifiers: Screen for compensatory deubiquitinases (e.g., USP7) via siRNA library screens in CAPNS1 KO cells.
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Clinical correlation: Analyze TCGA data for inverse CAPNS1-USP1 expression patterns in specific cancer subtypes .
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Key Parameters for CAPNS1 Studies
Product Science Overview
Calpain I and II are heterodimeric enzymes composed of distinct large subunits and a common small subunit . The small regulatory subunit, CSS1, consists of an N-terminal domain rich in glycine residues and a C-terminal calcium-binding domain . This structure is essential for the enzyme’s stability and function.
The activation of calpains is triggered by calcium influx and oxidative stress, which can lead to their involvement in neurodegenerative processes . Calpains have been implicated in various diseases, including pulmonary hypertension and spinal muscular atrophy .
Recombinant Human Calpain, Small Subunit 1 is a fragment protein expressed in Escherichia coli . It is typically produced with high purity (>95%) and is suitable for SDS-PAGE analysis . This recombinant protein is used in research to study the function and regulation of calpains, as well as their role in disease mechanisms.
The recombinant form of CSS1 is valuable in various research applications, including:
- Studying Calpain Activation: Understanding how calpains are activated and regulated in different cellular contexts.
- Disease Mechanisms: Investigating the role of calpains in diseases such as neurodegenerative disorders and muscular dystrophies.
- Drug Development: Screening for potential inhibitors of calpain activity that could be used as therapeutic agents.
