Spock2 Antibody

What is SPOCK2 and why is it relevant for research?

SPOCK2 is an extracellular matrix (ECM) protein belonging to the testican family that plays significant roles in cellular proliferation and development. Recent research has identified SPOCK2 as an inhibitor of immature β-cell proliferation through bidirectional expression modulation and single-cell RNA-seq analyses . Additionally, SPOCK2 has been implicated in lung alveolar development, with overexpression leading to altered lung morphology in mouse models . These findings highlight SPOCK2 as a relevant target for researchers studying developmental biology, diabetes, pulmonary development, and related pathologies.

What species reactivity can be expected from commercially available SPOCK2 antibodies?

Commercial SPOCK2 antibodies demonstrate cross-reactivity across multiple species. For instance, the polyclonal antibody AF2328 from Bio-Techne exhibits reactivity with human, mouse, and rat SPOCK2 proteins . Similarly, the Proteintech antibody (11725-1-AP) has confirmed reactivity with human samples, particularly in immunohistochemistry applications . When selecting an antibody for your research, it's essential to verify the specific species reactivity through the manufacturer's validation data, especially when working with less common experimental models.

What are the recommended dilutions for SPOCK2 antibody applications?

Different applications require specific antibody dilutions to achieve optimal results:

It's important to note that these dilutions serve as starting points, and researchers should optimize conditions for their specific experimental systems. As noted in the Proteintech documentation, "It is recommended that this reagent should be titrated in each testing system to obtain optimal results" .

How has SPOCK2 antibody been utilized to study β-cell proliferation and function?

Researchers have employed SPOCK2 antibodies to investigate the inhibitory effects of SPOCK2 on β-cell proliferation through several sophisticated approaches. In a recent study, recombinant human SPOCK2 (rh SPOCK2) protein was used to treat sorted CD49a+/TM4SF4- stem cell-derived β-cells (SC-β-cells), resulting in a 44% decrease in phospho-histone H3 positive (pHH3+) cells at concentrations of 250 ng/ml .

Similarly, when treating wild-type EndoC-βH1 cells with rh SPOCK2 for seven days, researchers observed a dose-dependent decrease in pHH3+ cells, confirming the anti-proliferative effect of SPOCK2 . These experiments demonstrate how SPOCK2 antibodies can be integrated into functional studies examining cellular proliferation in both primary and cell line models of pancreatic β-cells.

What role does SPOCK2 play in lung development and how have antibodies helped elucidate this function?

SPOCK2 antibodies have been instrumental in understanding the protein's role in lung development, particularly under hyperoxic conditions relevant to bronchopulmonary dysplasia (BPD). In a mouse model study, researchers administered goat anti-mouse SPOCK2 antibody (Bio-Techne AF2328) at 5 mg/kg to inhibit SPOCK2 function during lung development .

The antibody treatment revealed several key findings:

• In room-air conditions, anti-SPOCK2 antibody treatment did not significantly alter morphometric parameters of lung development

• Under hyperoxic conditions, anti-SPOCK2 antibody treatment significantly improved alveolarization, as measured by:

  • Decreased mean linear intercept (MLI) (p=0.024)

  • Increased alveolar surface values (p=0.026)

  • Increased alveolar surface density values (p=0.015)

These results suggest that SPOCK2 inhibition can partially protect against hyperoxia-induced lung injury, implicating SPOCK2 as a potential therapeutic target in neonatal lung injuries like BPD.

How do SPOCK2 antibodies help in understanding the protein's interaction with matrix metalloproteinases (MMPs)?

SPOCK2 antibodies have provided valuable insights into the relationship between SPOCK2 and matrix metalloproteinase 2 (MMP2) activation. Using anti-SPOCK2 antibodies, researchers demonstrated that SPOCK2 inhibition through specific antibody treatment led to a significant decrease in the activated fraction of MMP2 in room air conditions (21.8% in PBS-injected animals vs. 12.6% in animals injected with anti-SPOCK2 antibody; p=0.0027) .

This finding builds upon previous in vitro studies showing that SPOCK2 can abrogate the inhibition of MMP14 and MMP16 by other testican family members (SPOCK1 and SPOCK3) during the proteolysis of pro-MMP2 into its active form . Using antibodies as functional inhibitors, researchers were able to confirm SPOCK2's role in regulating MMP2 activation in vivo, providing a mechanistic understanding of how SPOCK2 influences extracellular matrix remodeling.

What are the optimal tissue fixation and antigen retrieval methods for SPOCK2 immunohistochemistry?

For successful SPOCK2 immunohistochemistry, proper tissue fixation and antigen retrieval are critical. According to Proteintech's protocol for antibody 11725-1-AP, the recommended antigen retrieval method uses TE buffer at pH 9.0 . Alternatively, citrate buffer at pH 6.0 can be used for antigen retrieval.

When preparing lung tissues for morphometric analysis and immunohistochemistry, researchers have successfully fixed specimens with 10% prefiltered formalin at a constant hydrostatic pressure of 25 cmH₂O for ≥20 minutes . This specific fixation protocol for lung tissue ensures preservation of alveolar architecture, which is essential for accurate morphometric measurements.

For SPOCK2 detection in different human tissues, positive IHC results have been reported in:

• Human testis tissue

• Human kidney tissue

• Human pancreas cancer tissue

• Human lung cancer tissue

These validated tissue sources can serve as positive controls when establishing SPOCK2 immunohistochemistry protocols in your laboratory.

What are the appropriate controls for validating SPOCK2 antibody specificity?

Establishing proper controls is essential for validating SPOCK2 antibody specificity. In the lung development study, researchers employed multiple control strategies:

• Negative controls: PBS injection served as a vehicle control

• Isotype controls: Control goat IgG (matching the host species of the anti-SPOCK2 antibody) was administered at the same concentration (5 mg/kg) as the specific antibody

• Validation of antibody localization: Immunohistochemistry using a detection kit for goat IgG (R.T.U. VECTASTAIN PK-7800) was performed on mouse lungs 6 hours after antibody injection to confirm the presence of the antibody in lung parenchyma

For Western blot applications, specificity can be confirmed by detecting a band of approximately 140 kDa under reducing conditions when using the Bio-Techne AF2328 antibody on rat lung tissue . This molecular weight is consistent with the glycosylated form of SPOCK2.

In transgenic models, antibody specificity can be further validated by comparing immunostaining intensity between control and SPOCK2-overexpressing animals, as demonstrated by the significantly more intense immunostaining in double-transgenic mice overexpressing SPOCK2 .

What buffer conditions are optimal for Western blot detection of SPOCK2?

Optimal buffer conditions for Western blot detection of SPOCK2 vary depending on the specific antibody used. When using the Sigma Aldrich SPOCK2 antibody, researchers have successfully employed overnight incubation at a 1:500 dilution in 0.125% nonfat dry milk . The table below summarizes effective buffer conditions for Western blot detection:

For detection, appropriate secondary antibodies should be selected based on the host species of the primary antibody. For example, HRP-conjugated anti-goat IgG secondary antibody (Bio-Techne HAF019) has been successfully used with the goat polyclonal AF2328 antibody . When using the Sigma Aldrich antibody, anti-rabbit secondary antibody at 1:20000 dilution in 0.125% nonfat dry milk with 20-minute incubation has yielded good results .

How can researchers address potential cross-reactivity with other testican family members?

SPOCK2 belongs to the testican family, which includes SPOCK1 and SPOCK3, proteins with similar domain structures. To address potential cross-reactivity:

• Select antibodies raised against unique epitopes: The Bio-Techne AF2328 antibody is generated against the region Glu23-Trp424 of human SPOCK2 (accession # Q92563) , which can be compared to corresponding regions in SPOCK1 and SPOCK3 to assess potential cross-reactivity.

• Validate with appropriate controls: When possible, use tissues or cells with known SPOCK2 knockout or overexpression as positive and negative controls. In published research, transgenic mice overexpressing SPOCK2 showed significantly increased immunostaining compared to controls, confirming antibody specificity .

• Consider pre-absorption controls: Pre-incubating the antibody with recombinant SPOCK2 protein should abolish specific staining, while pre-incubation with related family members should not affect staining if the antibody is truly specific.

• Verify by additional methods: Confirm SPOCK2 expression by complementary techniques such as RT-qPCR, as demonstrated in the lung development study where SPOCK2 protein detection by immunohistochemistry was correlated with gene expression data .

What factors affect SPOCK2 antibody performance in different experimental contexts?

Several factors can influence SPOCK2 antibody performance across experimental systems:

• Protein glycosylation: SPOCK2 is heavily glycosylated, which can affect epitope accessibility. Western blot detection using Bio-Techne AF2328 revealed a band at approximately 140 kDa , substantially higher than the calculated molecular weight of 47 kDa for the protein backbone , indicating extensive post-translational modification.

• Reduction conditions: The Bio-Techne experiments were conducted under reducing conditions , which may be necessary to expose certain epitopes within the SPOCK2 protein structure.

• Tissue-specific expression levels: SPOCK2 expression varies across tissues, with positive IHC detection reported in human testis, kidney, pancreatic cancer, and lung cancer tissues . Experimental design should account for these natural variations in expression level.

• Developmental timing: In the context of lung development, SPOCK2 expression is regulated developmentally and in response to environmental factors like hyperoxia . Researchers should consider developmental timing when designing experiments to detect SPOCK2 in embryonic or neonatal tissues.

• Antibody penetration in tissue sections: For in vivo studies using SPOCK2 antibodies as functional inhibitors, researchers confirmed antibody penetration into lung parenchyma by immunohistochemistry 6 hours after intraperitoneal injection , highlighting the importance of verifying antibody distribution in target tissues.

How can researchers quantify SPOCK2 expression levels in different experimental systems?

Researchers have employed several complementary approaches to quantify SPOCK2 expression:

• RT-qPCR for mRNA quantification: In transgenic models, SPOCK2 overexpression was confirmed by RT-qPCR, which revealed a median 30-fold increase in SPOCK2 mRNA expression in double-transgenic mice compared to controls (p=0.001) .

• Immunohistochemistry with semi-quantitative analysis: SPOCK2 protein expression was quantified by measuring immunostaining intensity, which was significantly higher in SPOCK2-overexpressing mice compared to controls (p=0.048) .

• Western blot with densitometry: For relative quantification of SPOCK2 protein levels, Western blot combined with densitometric analysis can be employed, using housekeeping proteins like α-tubulin or GAPDH as loading controls .

• ELISA for secreted SPOCK2: For quantifying antibody concentrations in tissue extracts, researchers have used ELISA methods, such as the Goat IgG ELISA Kit used to measure anti-SPOCK2 antibody concentrations in mouse lungs following intraperitoneal injection .

• MMP2 activation assay as a functional readout: Since SPOCK2 influences MMP2 activation, researchers have used gelatin zymography to quantify the activated fraction of MMP2 as a functional readout of SPOCK2 activity or inhibition .

Each of these methods provides different insights into SPOCK2 biology, and combining multiple approaches can provide a more comprehensive understanding of SPOCK2 expression and function in experimental systems.