Cleaved-SPTAN1 (D1185) Antibody

What is SPTAN1 and what is the significance of the D1185 cleaved form?

SPTAN1 (Spectrin alpha Chain, Brain) is a non-erythrocytic alpha-II spectrin that functions as a critical component of the cytoskeleton. The protein plays essential roles in maintaining cellular structure, membrane stability, and various cellular processes. The D1185 cleaved form refers specifically to a fragment of SPTAN1 resulting from proteolytic cleavage adjacent to the aspartate residue at position 1185. This cleavage is typically mediated by calpain or caspase-3 during specific cellular processes including apoptosis and neural cell pathology . The detection of this cleaved fragment serves as an important biomarker for cellular stress, neurodegeneration, and certain pathological conditions.

How does SPTAN1 cleavage occur and what cellular processes does it indicate?

SPTAN1 cleavage is predominantly mediated through two pathways:

• Calpain-mediated cleavage: Activated during calcium dysregulation

• Caspase-3-mediated cleavage: Activated during apoptotic cell death

Research has demonstrated that proteolysis of αII spectrin (SPTAN1) represents an early event in neural cell pathology . The spectrin breakdown products resulting from calpain and caspase-3 activity are observed in numerous neurodegenerative conditions, suggesting that SPTAN1 cleavage serves as both a mechanistic component and a biomarker of neuronal injury . Additionally, during early apoptosis, spectrin undergoes aggregation in certain cell lines, transitioning from a soluble to an insoluble protein within the Triton X-100 insoluble cellular fraction .

Experimental Applications and Methodologies

For optimal detection of cleaved SPTAN1 in research samples, the following methodological approach is recommended:

• Sample Preparation:

  • For cell cultures: Lyse cells in ice-cold RIPA buffer (150 mM NaCl, 1% NP-40, 0.5% sodium deoxycholate, 0.1% SDS, 50 mM Tris, pH 8) supplemented with protease inhibitor cocktail .

  • For tissue samples: Homogenize in appropriate lysis buffer with protease inhibitors.

• Western Blotting Protocol:

  • Separate 30 μg total protein using 7.5% SDS-PAGE .

  • Transfer proteins to PVDF or nitrocellulose membrane.

  • Block membrane using 5% non-fat dry milk for 1 hour at room temperature.

  • Incubate with primary Cleaved-SPTAN1 (D1185) antibody (1:1000 dilution) overnight at 4°C.

  • Apply appropriate secondary antibody (typically IRDye® 680 LT or equivalent).

  • Image using standard detection systems (e.g., FLA-9000 scanner or similar) .

• Controls:

  • Include α-tubulin or β-actin as loading controls.

  • Use both positive controls (staurosporine-treated cells) and negative controls (untreated samples) .

How can researchers experimentally induce SPTAN1 cleavage for positive controls?

To generate positive controls for cleaved SPTAN1 detection, the following induction methods have been validated in the literature:

• Staurosporine Treatment:

  • Culture primary fibroblasts or relevant cell lines in medium supplemented with 1 μM staurosporine.

  • Collect samples at various time points (0h, 4h, 24h, and 48h) to observe progression of cleavage.

  • Replace medium with fresh staurosporine-supplemented medium every 24 hours .

• Thapsigargin Treatment:

  • Treatment with thapsigargin has been demonstrated to induce SPTAN1 cleavage in mouse diaphragm tissue, generating a detectable 136 kDa cleaved fragment .

• Other Apoptosis Inducers:

  • Additional compounds that induce apoptosis through various mechanisms can also generate cleaved SPTAN1, though staurosporine remains the most commonly used control.

How does SPTAN1 cleavage relate to neurological disorders and hearing loss?

SPTAN1 has been implicated in several neurological conditions, particularly epileptic encephalopathies. Research findings indicate:

• Epileptic Encephalopathies:

  • Pathogenic variants in SPTAN1 have been associated with a spectrum of epilepsy phenotypes ranging from isolated epilepsy to severe developmental conditions .

  • Aggregation or cleavage of αII spectrin may play a mechanistic role in SPTAN1 encephalopathy .

• Hearing Loss and Cochlear Hair Cell Function:

  • SPTAN1 is abundant in the cuticular plate of hair cells, surrounding the rootlets of stereocilia and along the plasma membrane.

  • Mice with hair cell-specific knockout of Sptan1 (Sptan1-CKO) show significant hearing phenotypes, demonstrating its essential role in cochlear hair cell morphology and function .

  • Researchers investigating hearing loss may use cleaved SPTAN1 antibodies to analyze the relationship between SPTAN1 proteolysis and auditory dysfunction.

What is the relationship between SPTAN1 expression/cleavage and cancer progression?

Research has established significant correlations between SPTAN1 and cancer outcomes, particularly in colorectal cancer:

• Prognostic Value:

  • Higher SPTAN1 protein and mRNA levels in colorectal cancer specimens associate with longer patient survival times .

  • SPTAN1 expression levels may serve as a biomarker for predicting treatment and survival outcomes in colorectal cancer patients.

• Chemotherapy Response:

  • Cells with reduced SPTAN1 expression demonstrate decreased susceptibility to FOLFOX chemotherapy, a standard treatment regimen for colorectal cancer patients .

  • This suggests that SPTAN1 status may influence therapeutic efficacy and could guide treatment decisions.

Researchers studying cancer progression may utilize Cleaved-SPTAN1 (D1185) antibodies to investigate whether the ratio of cleaved to intact SPTAN1 correlates with tumor aggressiveness, metastatic potential, or treatment response.

How can SPTAN1 knockdown models be generated for functional studies?

For researchers investigating SPTAN1 function through loss-of-function approaches, the literature describes several validated methodologies:

• shRNA Knockdown:

  • Lentiviral vectors expressing shRNA targeting SPTAN1 have been successfully employed with the following target sequence: 5′-CATAACTAAGGAGGCCGGCAGTGTA-3′ .

  • Non-relevant shRNA (5′-TTCTCCGAACGTGTCACGTAA-3′) serves as an appropriate control.

  • Transfection efficiency can be verified through Western blotting and through co-expression of GFP markers .

• CRISPR-Cas9 Gene Editing:

  • In vivo deletion of Sptan1 has been achieved using CRISPR-Cas9 technology with specifically designed gRNAs.

  • Approximately 80% deletion efficiency has been reported in neuronal models using this approach .

  • Immunostaining for the protein provides a more accurate assessment of deletion efficiency than molecular quantification of indels .

What factors might affect the detection of cleaved SPTAN1 in experimental settings?

Several technical factors can influence the reliable detection of cleaved SPTAN1:

• Sample Preparation:

  • Rapid processing of samples is critical as post-mortem or delayed processing can result in artifactual SPTAN1 cleavage.

  • Inclusion of appropriate protease inhibitors is essential to prevent ex vivo cleavage during sample handling.

• Antibody Specificity:

  • Some antibodies detect only the cleaved fragment while others might detect both full-length SPTAN1 and cleaved fragments.

  • For example, the anti-α fodrin antibody detects both full-length αII spectrin and the cleaved 150 kDa fragment .

  • Researcher should verify whether their selected antibody is cleavage-specific or recognizes multiple forms.

• Protein Aggregation:

  • During apoptosis, spectrin can aggregate and shift from soluble to insoluble fractions, potentially affecting extraction efficiency .

  • Different extraction methods may be required to thoroughly analyze all cellular pools of SPTAN1.

How can researchers verify the specificity of Cleaved-SPTAN1 (D1185) antibodies?

To ensure experimental validity, researchers should implement the following verification steps:

• Positive Controls:

  • Include known inducers of SPTAN1 cleavage (e.g., staurosporine-treated samples).

  • Time-course experiments can demonstrate progressive accumulation of the cleaved fragment.

• Negative Controls:

  • Untreated samples should show minimal to no cleaved fragment.

  • Pre-absorption of the antibody with the immunizing peptide should abolish signal.

• Molecular Weight Verification:

  • The cleaved SPTAN1 fragment should appear at the expected molecular weight (approximately 136-150 kDa, depending on the exact cleavage site) .

• Multiple Detection Methods:

  • When possible, confirm results using alternative antibodies or detection methods.

What are the storage and handling recommendations for Cleaved-SPTAN1 (D1185) antibodies?

For optimal antibody performance and longevity, the following storage and handling guidelines should be observed:

• Storage Conditions:

  • Store antibodies at -20°C for up to 1 year from the date of receipt .

  • Avoid repeated freeze-thaw cycles to maintain antibody activity.

• Working Solution Preparation:

  • Commercial antibodies are typically formulated in PBS containing 50% glycerol, 0.5% BSA, and 0.02% sodium azide .

  • Dilute antibodies immediately before use according to the recommended dilution ranges for specific applications.

• Safety Considerations:

  • These research antibodies are strictly for scientific research use only (RUO) and must not be used in diagnostic or therapeutic applications .