CTSO Antibody

What is CTSO and where is it expressed in the body?

CTSO is one of the 11 cysteine-type papain-like cathepsins identified in humans, about which relatively little is known . It functions as a proteolytic enzyme involved in normal cellular protein degradation and turnover . CTSO is expressed in all tissues examined, with high levels detected in the ovary, kidney, and placenta, while lower levels are observed in thymus and skeletal muscle . Studies have also confirmed CTSO expression in cerebral artery walls, endothelial cells, and more strongly in vascular smooth muscle cells (VSMCs) .

What applications are CTSO antibodies validated for?

CTSO antibodies are validated for multiple research applications as summarized in the table below:

How does CTSO contribute to vascular function and arterial remodeling?

Recent studies have identified CTSO as a potential actor in arterial remodeling through several mechanisms :

• CTSO controls vascular smooth muscle cell (VSMC) migration and adhesion to the extracellular matrix

• CTSO depletion leads to increased VSMC stiffness

• CTSO is involved in fibronectin (FN) regulation, with evidence suggesting it degrades pericellular FN

• The extracellular release of CTSO is stimulated by cell stretching, suggesting its role as an extracellular protease in the arterial wall could be potentiated by high blood pressure

These findings indicate that CTSO plays a critical role in the maintenance of vascular wall integrity and remodeling processes.

What is the relationship between CTSO variants and intracranial aneurysm?

Through whole exome sequencing (WES) and identity-by-descent (IBD) analysis, researchers have identified rare coding variants in the CTSO gene as causally related to familial forms of intracranial aneurysm (IA) . Specific mutations like p.Val316Ile-CTSO and p.Ala43Val-CTSO were found to be weakly secreted and induced increased fibronectin amounts, similar to the effect of CTSO depletion . The increased susceptibility to IA induced by CTSO variants is likely related to their primary effects on vascular tissue, particularly the media layer of cerebral arteries .

How does CTSO silencing affect VSMC function in experimental models?

Research has revealed several important effects of CTSO silencing on VSMCs:

• CTSO silencing significantly decreases VSMC transmigration capacity

• CTSO depletion accelerates cell adhesion to substrate

• CTSO silencing does not affect VSMC proliferation or apoptosis, even after staurosporine treatment

• Adhesion and focal adhesion kinase (FAK) activation are potentiated by depletion of CTSO, both rapidly and late after VSMC seeding on exogenous FN coating

• CTSO-depleted VSMCs show increased amounts of fibronectin

These findings suggest a specific role for CTSO in regulating cell-matrix interactions without affecting cell viability or proliferation.

How is CTSO expression and secretion regulated by mechanical stress?

Experimental evidence indicates that CTSO secretion is modulated by mechanical forces:

• In VSMC cultures, CTSO was found in both cell lysates and culture medium, indicating active secretion of the protein

• CTSO secretion is significantly potentiated by cellular stretch without any change in mRNA levels, suggesting post-transcriptional regulation

• The extracellular release of CTSO likely occurs through lysosomal exocytosis and is stimulated by mechanical stress

• This mechanosensitive regulation of CTSO secretion suggests it may participate in arterial remodeling induced by hypertension

What are the optimal protocols for Western blot analysis using CTSO antibodies?

Based on multiple antibody supplier recommendations, the following protocol elements are critical for successful Western blot analysis of CTSO:

For optimal results, include protease inhibitors during sample preparation and confirm specificity using appropriate positive and negative controls.

What are the best practices for immunohistochemistry with CTSO antibodies?

For successful immunohistochemical detection of CTSO:

Include appropriate positive and negative controls in each experiment and optimize antigen retrieval conditions for your specific tissue samples.

How should researchers validate the specificity of CTSO antibodies?

Comprehensive validation of CTSO antibodies should include:

• Western blot analysis confirming the expected 36 kDa band

• Testing in known positive control samples:

  • Transfected HEK-293 cells for Western blot and IP

  • Human ovary tumor tissue for IHC

• Knockout/knockdown validation:

  • Compare results in cells with and without CTSO silencing (siRNA)

• Cross-reactivity testing if working with multiple species:

  • Several antibodies are validated for human, mouse, and rat samples

• Multi-application validation:

  • Confirm consistent results across different detection methods (WB, IHC, etc.)

What are the optimal conditions for immunoprecipitation of CTSO?

For successful immunoprecipitation of CTSO:

• Use 0.5-4.0 μg of antibody for 1.0-3.0 mg of total protein lysate

• HEK-293 cells serve as a validated positive control for IP experiments

• Ensure thorough pre-clearing of lysates to reduce non-specific binding

• Include appropriate controls (IgG control, input sample)

• Follow manufacturer-specific protocols for optimal results

How can researchers effectively study CTSO in vascular smooth muscle cells?

Based on research methodologies described in the literature:

• Cell culture models:

  • Primary VSMCs or established cell lines are suitable

  • Both rat and human VSMCs have been successfully used

• Silencing approaches:

  • siRNA-mediated depletion (referred to as KD-SMC in studies)

  • Monitor silencing efficiency by Western blot

• Functional assays:

  • Migration: Boyden chamber assays

  • Adhesion: Cell attachment assays to fibronectin or plastic

  • Stiffness: Appropriate mechanical testing methods

• Expression analysis:

  • Monitor both intracellular and secreted CTSO

  • Apply mechanical stress (stretch) to study regulation of secretion

• ECM interaction studies:

  • Analyze fibronectin levels and deposition in CTSO-depleted conditions

  • Monitor focal adhesion kinase (FAK) activation