S100A15 Mouse

What is mS100a7a15 and how does it relate to human S100 proteins?

mS100a7a15 is the murine ortholog of human S100A7 (Psoriasin) and human S100A15 (Koebnerisin). It is also known by several aliases including S100a15, mS100a7, and mS100a7a, and is encoded by the mS100a7a gene (alias: S100a15). The protein belongs to the S100 calcium-binding family, which mediates fundamental cellular and extracellular processes including cell proliferation, differentiation, migration, and antimicrobial host defense .

This mouse ortholog parallels the genomic organization, structure, gene expression, and protein-processing pattern of the human S100A7/A15 subfamily, making it valuable for translational research. Importantly, mS100a7a15 can serve as a surrogate model to study hS100A7 and hS100A15 functions in various physiological and pathological contexts .

What are the primary physiological functions of mouse S100A15?

mS100a7a15 performs several important physiological functions across different tissue types:

In skin: It is localized to the epidermal granular and cornified layers of the interfollicular epidermis and to the maturing cells of hair follicles in newborn mouse skin. In maturing keratinocytes, mS100a7a15 is induced by calcium-mediated differentiation dependent on protein kinase C (PKC). Additionally, it is upregulated in a TLR4-dependent manner by E. coli stimulation and might have antimicrobial effects similar to its human counterparts .

In breast tissue: mS100a7a15 is weakly expressed in normal mammary gland tissue but becomes upregulated in DMBA-induced mammary gland tumors, specifically in epithelial tumor cells .

In inflammatory conditions: The protein is upregulated in inflammatory contexts, suggesting a role in immune response mechanisms .

How does S100A15 contribute to cancer progression in mouse models?

Research has demonstrated that mS100a7a15 plays significant roles in cancer progression, particularly in breast cancer models. When overexpressed in mammary epithelial cells, mS100a7a15 enhances proliferation, angiogenesis, and metastasis through the induction of prometastatic and angiogenic factors including CCL2, Cox-2, MMP2, MMP9, and VEGF .

Furthermore, mS100a7a15 recruits tumor-associated macrophages (TAMs) through RAGE and Stat3 activation mechanisms to promote tumorigenesis . This finding parallels human studies, such as research on lung adenocarcinoma where increased S100A15 nuclear staining correlates with distant metastasis and reduced survival rates .

The mechanistic insights from these mouse models can be valuable for understanding comparable human cancer pathways, as RNA sequencing analysis has identified potential downstream mediators of S100A15 including CTNNB1, ZEB1, CDC42, HSP90AA1, BST2, and PCNA .

What epigenetic mechanisms regulate S100A15 expression in disease models?

Evidence from lung cancer research indicates that DNA methylation plays a crucial role in regulating S100A15 expression. Specifically, decreased DNA methylation levels over the -423 and -248 CpG sites of the S100A15 gene promoter have been observed in adenocarcinoma patients with distant metastasis .

In cellular models, highly invasive CL1-5 cell lines display decreased DNA methylation over the –412/-248/-56 CpG sites of the S100A15 gene promoter, which corresponds with increased S100A15 gene/protein expressions compared to less invasive CL1-0 cell lines .

These findings suggest that epigenetic modifications, particularly promoter DNA methylation, significantly influence S100A15 expression patterns in disease states. Researchers working with mouse models should consider incorporating epigenetic analyses when studying S100A15 regulation in various pathological conditions.

How do the splice variants of S100A15 differ functionally in mouse models?

S100A15 exists in multiple splice variants, with research identifying both long form (LF) and short form (SF) variants. RNA sequencing and real-time quantitative RT-PCR analyses have shown that gene expressions of both S100A15 splice variants are significantly increased in highly metastatic cell lines compared to those with low metastatic potential .

While the distinct functional roles of these splice variants are still being elucidated, this observation suggests potential differential contributions to metastatic processes. Researchers should consider designing experiments that can specifically detect and distinguish between these variants to better understand their respective roles in normal physiology and disease states.

What are the optimal conditions for handling recombinant mouse S100A15 protein in experiments?

When working with recombinant mouse S100A15 protein, researchers should consider the following handling conditions to maintain protein stability and functionality:

Storage: Store at 4°C if the entire vial will be used within 2-4 weeks. For longer periods, store frozen at -20°C. For long-term storage, it is recommended to add a carrier protein (0.1% HSA or BSA) to prevent protein degradation .

Formulation: Typically, recombinant S100A15 is supplied in a solution containing 20mM Tris-HCl buffer (pH 8.0), 150mM NaCl, and 20% glycerol . Alternative formulations may include additional components such as 1mM DTT for maintaining reducing conditions .

Handling precautions: Avoid multiple freeze-thaw cycles as this can lead to protein denaturation and loss of activity. Use sterile techniques when handling to prevent contamination .

Purity considerations: Commercially available recombinant S100A15 typically has a purity greater than 85-95% as determined by SDS-PAGE. Researchers should verify the purity requirements for their specific experimental applications .

What techniques are most effective for studying S100A15 expression in mouse tissues?

Several complementary techniques have proven effective for studying S100A15 expression in mouse tissues:

Immunohistochemistry (IHC): Particularly useful for localizing S100A15 protein expression within tissue contexts. In skin studies, IHC has successfully demonstrated S100A15 localization to specific epidermal layers and hair follicle cells . For quantification, scoring systems that account for both staining intensity and percentage of positive cells can be employed .

Real-time quantitative RT-PCR: Effective for measuring gene expression levels of S100A15 and distinguishing between splice variants. This technique has been successfully used to compare expression levels between cell lines with different metastatic potentials .

RNA sequencing: Provides comprehensive gene expression profiling and can identify relationships between S100A15 and other genes in the same pathways or networks .

Pyrosequencing: Valuable for measuring DNA methylation levels at specific CpG sites in the S100A15 gene promoter, which can correlate with expression patterns .

What experimental approaches are most suitable for investigating S100A15 function in mouse models?

To investigate S100A15 function in mouse models, several experimental approaches have proven informative:

Knockdown and overexpression studies: RNA interference to knockdown S100A15 or transfection to overexpress it can reveal its roles in cell proliferation, migration, and invasion. These approaches have demonstrated that S100A15 knockdown inhibits these cellular processes while overexpression promotes them .

Calcium-induced differentiation models: Since S100A15 expression is upregulated in keratinocytes stimulated to differentiate by calcium or phorbol esters, calcium-switch experiments can be valuable for studying its role in epithelial differentiation .

Inflammatory challenge models: Given S100A15's upregulation in inflammatory conditions, models involving TLR4-dependent pathways or E. coli stimulation can help elucidate its role in innate immunity and antimicrobial defense .

Carcinogenesis models: DMBA-induced mammary gland tumors in mice have been used to study S100A15's role in breast cancer development and progression .

How should researchers interpret changes in S100A15 nuclear versus cytoplasmic localization?

The subcellular localization of S100A15 provides important functional insights that require careful interpretation:

Significance of nuclear localization: Increased nuclear staining of S100A15 has been associated with advanced disease stage and distant metastasis in lung adenocarcinoma patients . When analyzing mouse tissues, researchers should quantify nuclear staining separately from cytoplasmic staining using scoring systems that account for both intensity and percentage of positively stained cells.

Quantification approach: A comprehensive scoring system might include:

• Intensity score (0=negative, 1=weak, 2=moderate, 3=strong)

• Percentage score (0=<5%, 1=5-25%, 2=26-50%, 3=51-75%, 4=>75%)

• Total score (sum of intensity and percentage scores)

Prognostic implications: High nuclear expression of S100A15 (typically defined as a total score ≥4) has been associated with poorer survival outcomes in certain cancer models . Researchers should consider longitudinal studies when investigating S100A15 as a potential prognostic marker in mouse disease models.

What are the key considerations when analyzing the relationship between S100A15 methylation status and gene expression?

When investigating the relationship between S100A15 methylation status and gene expression, researchers should consider:

Site-specific effects: Different CpG sites in the S100A15 promoter (such as -423, -248, and -56) may have varying impacts on gene expression. Analysis should examine individual sites rather than just average methylation across the promoter region .

Correlation analysis: Statistical methods should be employed to quantify the relationship between methylation levels at specific sites and corresponding gene expression, considering both mRNA and protein levels.

Functional validation: After identifying correlations between methylation changes and expression, functional studies (such as site-directed mutagenesis or methylation editing) should be conducted to establish causality.

Cell type specificity: Methylation patterns and their impact on expression may vary across different cell types within the same tissue. Single-cell approaches may be necessary to fully understand these relationships in heterogeneous tissues.