SDF 1b Mouse
Description
Introduction to SDF-1β Mouse
Stromal Cell-Derived Factor-1 beta (SDF-1β/CXCL12b) is a splice variant of the CXCL12 chemokine family, critical for hematopoietic stem cell migration, embryogenesis, and immune cell regulation. In mice, SDF-1β is produced via alternative splicing of the CXCL12 gene and shares 99% sequence identity with human CXCL12 . It binds primarily to the CXCR4 receptor and secondarily to CXCR7, enabling signaling pathways that regulate cellular migration, survival, and differentiation . Mice lacking CXCL12 or its receptors exhibit perinatal lethality with severe defects in B-lymphopoiesis, myelopoiesis, and organogenesis .
Physicochemical Stability
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Lyophilized Form: Stable at room temperature for 3 weeks; long-term storage requires desiccation below -18°C .
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Reconstitution: Optimal solubility in sterile H₂O (≥100 µg/ml); carrier proteins (0.1% HSA/BSA) recommended for enhanced stability .
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Shelf Life: Reconstituted protein remains active at 4°C for 2–7 days .
Hematopoietic Cell Mobilization
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Sulfated polysaccharides (e.g., FucS) induce rapid SDF-1β plasma elevation in mice (11.6 ng/mL after one 100 mg/kg dose), correlating with increased circulating hematopoietic progenitors .
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Bone marrow SDF-1α levels drop to 60% of baseline within 0.5 hours post-FucS treatment, creating a chemotactic gradient that mobilizes stem cells .
Developmental Roles
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B-Lymphopoiesis: SDF-1β is chemotactic for pro- and pre-B cells via CXCR4, critical for their confinement and maturation in bone marrow .
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Pancreatic β-Cell Survival: Transgenic mice overexpressing SDF-1 in β-cells (RIP-SDF-1) resist streptozotocin-induced diabetes due to enhanced Akt phosphorylation and reduced apoptosis .
Neurological and Vascular Development
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CXCL12 knockout mice exhibit defective cerebellar neuronal migration and abnormal vascular patterning .
Functional Assays and Quantitation Methods
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Protein Quantitation:
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Biological Activity:
Applications in Experimental Models
Product Specs
Q&A
What is the structural difference between SDF-1α and SDF-1β in mice?
SDF-1α and SDF-1β are encoded by a single gene and arise through alternative splicing. The proteins are identical except for four additional amino acid residues present in the carboxy-terminus of SDF-1β that are absent in SDF-1α. Both SDF-1α and SDF-1β cDNAs encode precursor proteins of 89 and 93 amino acid residues, respectively . This structural difference, while subtle, may contribute to functional variations in specific biological contexts.
How conserved is mouse SDF-1β compared to human SDF-1β?
SDF-1/PBSF demonstrates remarkable evolutionary conservation between species. There is only a single amino acid substitution between mature human and mouse SDF-1 proteins . This high degree of conservation suggests critical functional importance throughout mammalian evolution and explains why mouse models are particularly valuable for translational research in this area.
Which receptor does mouse SDF-1β primarily signal through?
Mouse SDF-1β, like SDF-1α, primarily signals through the chemokine receptor CXCR4 . This receptor-ligand interaction mediates various biological functions, including chemotaxis, cell survival, and proliferation. Understanding this signaling pathway is essential for designing experiments that target or utilize the SDF-1/CXCR4 axis in mouse models.
How does SDF-1β function in mouse experimental stroke models?
In mouse experimental stroke models, SDF-1 plays a critical role in hematopoietic stem cell mobilization and recruitment. Research shows that administration of Lin−/Sca1+ cells post-stroke significantly reduces infarct volume at 24 hours, but this beneficial effect is negated when SDF-1 antibody is co-administered .
Furthermore, stroke mice treated with SDF-1 antibody demonstrate increased Lin−/Sca1+ cells in the bone marrow and decreased mobilization to the blood compared to controls . This suggests that SDF-1 facilitates the mobilization of these progenitor cells from bone marrow to circulation and ultimately to the site of ischemic injury.
| Condition | Lin−/Sca1+ cells in bone marrow | Lin−/Sca1+ cells in blood | Infarct volume reduction |
|---|---|---|---|
| Stroke only | Decreased | Increased | N/A |
| Stroke + SDF-1 antibody | Increased | Decreased | None |
| Stroke + Lin−/Sca1+ cell administration | N/A | N/A | Significant |
| Stroke + Lin−/Sca1+ cells + SDF-1 antibody | N/A | N/A | None |
What mechanisms underlie SDF-1's role in tumor invasiveness in mouse glioma models?
In the ALTS1C1 murine brain tumor model, which recapitulates features of human high-grade glioma, SDF-1/CXCL12 expression has been associated with tumor invasiveness and tumor-associated macrophage (TAM) recruitment .
When SDF-1 expression was inhibited via siRNA in ALTS1C1 cells (SDF kd), significant changes in tumor behavior were observed:
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SDF kd tumors took longer to form
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SDF kd tumors exhibited well-defined regular borders without infiltration tracts
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SDF kd tumors showed lower microvascular density (MVD)
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SDF kd tumors contained more hypoxic areas
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TAM distribution was altered, with higher density in non-hypoxic regions versus hypoxic regions (opposite to parental tumors)
These findings suggest that SDF-1 produced by tumor cells is critical for both TAM aggregation in hypoxic areas and promoting tumor invasiveness, making it a potential therapeutic target for invasive brain tumors.
How do genetic knockouts of SDF-1 affect mouse development and physiology?
Mice lacking SDF-1 or its receptor CXCR4 exhibit multiple severe developmental abnormalities, indicating the critical role of this signaling axis in embryogenesis and tissue development. Specifically, these knockout mice demonstrate:
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Impaired B-lymphopoiesis
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Defective myelopoiesis
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Abnormal vascular development
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Cardiogenesis defects
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Abnormal neuronal cell migration and patterning in the central nervous system
The comprehensive developmental impact of SDF-1 deficiency highlights its fundamental role in multiple organ systems and suggests that conditional or tissue-specific knockout approaches may be more suitable for studying its function in adult mice.
What are the effective methods to detect SDF-1β in mouse tissue samples?
Several methods can be employed to detect SDF-1β in mouse tissue samples, each with specific advantages:
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Immunohistochemistry/Immunofluorescence: Utilize specific antibodies like clone 79014 that recognize both human and mouse CXCL12/SDF-1 . This allows visualization of SDF-1 distribution within tissue architecture.
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Western Blot: Effective for semi-quantitative analysis of SDF-1β protein levels in tissue homogenates. This method can distinguish SDF-1α and SDF-1β based on molecular weight differences due to the additional four amino acids in SDF-1β .
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Flow Cytometry: Useful for detecting SDF-1β in specific cell populations within complex tissues.
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In vivo functional assays: Measuring biological activities dependent on SDF-1, such as chemotaxis assays using the BaF3 mouse pro-B cell line transfected with human CXCR4 .
When selecting antibodies, researchers should note that many antibodies cross-react between human and mouse SDF-1 due to the high sequence homology.
How can researchers effectively neutralize SDF-1 function in mouse models?
Several approaches can be employed to neutralize SDF-1 function in mouse models:
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Neutralizing antibodies: The clone 79014 antibody has demonstrated efficacy in neutralizing CXCL12/SDF-1α-induced chemotaxis. At a concentration of 111 μg/mL, this antibody neutralizes >50% of the chemotactic effect induced by 2 ng/mL of recombinant SDF-1α .
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CXCR4 antagonists: Since SDF-1 signals through CXCR4, blocking this receptor effectively neutralizes SDF-1 function.
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siRNA knockdown: As demonstrated in the ALTS1C1 tumor model, specific siRNA targeting SDF-1 can effectively reduce its expression and function .
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Conditional knockout models: For tissue-specific or temporal control of SDF-1 expression.
The selection of neutralization method should be guided by experimental design considerations, including duration of inhibition needed, tissue specificity, and potential off-target effects.
What are optimal experimental conditions for studying SDF-1β-induced chemotaxis in mouse cells?
For studying SDF-1β-induced chemotaxis in mouse cells, the following methodology has been validated:
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Cell selection: The BaF3 mouse pro-B cell line transfected with human CXCR4 provides a reliable system for studying SDF-1-induced chemotaxis .
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SDF-1 concentration: A dose-response curve should be established, but 2 ng/mL of recombinant SDF-1α has been shown to elicit significant chemotactic responses .
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Chemotaxis assay setup: Transwell migration assays with appropriate pore sizes based on the cell type being studied.
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Controls: Include both negative controls (media alone) and positive controls (known chemoattractants for the cell type).
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Neutralization controls: Inclusion of neutralizing antibodies (such as clone 79014 at 111 μg/mL) can confirm the specificity of SDF-1-induced migration .
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Quantification: Cell counts in the lower chamber or automated imaging techniques for objective quantification.
This methodology allows for reliable assessment of SDF-1β's chemotactic effects and is adaptable to various mouse cell types that express CXCR4.
How does SDF-1β function in mouse models of diabetic wound healing?
Recent research has investigated the role of growth factors in diabetic wound healing, which may have implications for understanding SDF-1β function. In both Type 1 and Type 2 diabetic mouse models, certain growth factors like GDF11 have been shown to accelerate the healing of full-thickness skin wounds .
While the search results don't specifically detail SDF-1β's role in diabetic wound healing, understanding the methodological approaches used in these models is valuable for researchers investigating SDF-1β in this context:
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Type 1 diabetes model: Single intraperitoneal injection of streptozotocin (180 μg/g) with verification of diabetes by fasting blood glucose levels >11.5 mM .
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Type 2 diabetes model: Leptin-receptor-deficient db/db mice with verification by random fasting blood glucose levels >30 mM .
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Wound model: Full-thickness 5-mm diameter wounds created on the mouse dorsum using sterile punch biopsy .
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Treatment application: Topical application of test compounds twice daily until epidermal closure (maximum 14 days) .
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Assessment: Digital imaging of wounds daily to track healing progress, with wound area defined as the area surrounded by visible edge of dermis .
These methodological approaches could be adapted to study SDF-1β's effects in diabetic wound healing.
What is the role of SDF-1β in mouse embryonic stem cell regulation?
SDF-1/CXCL12 plays critical roles in mouse embryonic stem cell (ESC) regulation, particularly enhancing survival, chemotaxis, and hematopoietic differentiation . Research has shown that SDF-1 and its receptor CXCR4 are important regulators of:
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Survival/antiapoptosis: SDF-1 promotes survival of mouse embryonic stem cells .
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Hematopoietic differentiation: SDF-1 promotes production of both primitive and definitive hematopoietic progenitor cells from mouse ESCs .
Understanding these functions is crucial for researchers looking to control ESC growth and differentiation ex vivo for potential therapeutic applications. The SDF-1/CXCR4 axis represents a key regulatory pathway that can be targeted to enhance ESC survival and directed differentiation toward specific lineages.
How can single-cell analysis techniques advance our understanding of SDF-1β function in mouse models?
While traditional techniques have provided valuable insights into SDF-1β function, emerging single-cell technologies offer opportunities to uncover previously undetectable patterns:
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Single-cell RNA sequencing (scRNA-seq): Can reveal cell-specific expression patterns of SDF-1β and CXCR4 across heterogeneous tissues, identifying new cell populations responsive to SDF-1 signaling.
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Single-cell proteomics: May detect post-translational modifications of SDF-1β that affect its function.
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Spatial transcriptomics: Can map the spatial distribution of SDF-1β expression relative to responding cells, particularly valuable in developmental contexts or tumor microenvironments.
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CRISPR-based lineage tracing: Can track the fate of SDF-1-responsive cells during development or disease progression.
These approaches could overcome limitations of bulk analysis methods that mask cellular heterogeneity and provide new insights into the context-specific functions of SDF-1β in mouse models.
What are the emerging therapeutic applications of modulating SDF-1β in mouse disease models?
Based on its diverse biological functions, modulation of SDF-1β shows therapeutic potential in several disease contexts:
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Stroke recovery: Enhancing SDF-1 signaling could improve mobilization of stem/progenitor cells to sites of ischemic injury, potentially reducing infarct volume and improving functional recovery .
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Cancer therapy: Inhibiting SDF-1 in glioma models reduces tumor invasiveness and alters tumor-associated macrophage distribution, suggesting potential for combined targeting of SDF-1 with conventional therapies .
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Stem cell therapy: Manipulating SDF-1/CXCR4 signaling could enhance survival and homing of therapeutic stem cells .
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Wound healing: Potential application in chronic wounds, particularly in diabetic models where wound healing is impaired .
These applications highlight the translational potential of basic research on SDF-1β in mouse models to human therapeutic development.
Product Science Overview
SDF-1β is a non-glycosylated protein composed of 72 amino acids with a molecular weight of approximately 8.5 kDa . It belongs to the CXC chemokine family, characterized by the presence of four conserved cysteines that form two disulfide bonds. The initial pair of cysteines in CXC chemokines are separated by one intervening amino acid .
CXCL12 is ubiquitously expressed in many tissues and cell types, including the brain, thymus, heart, lung, liver, kidney, spleen, platelets, and bone marrow . It is strongly chemotactic for lymphocytes and plays a significant role in the migration and recruitment of activated leukocytes . During embryogenesis, CXCL12 directs the migration of hematopoietic cells from the fetal liver to the bone marrow and aids in the formation of large blood vessels .
SDF-1β signals through the G protein-coupled receptor CXCR4 to recruit activated leukocytes . This signaling pathway is crucial for various immune responses and has been observed in several cancers . Additionally, CXCL12 signaling is involved in the regulation of stem cell homing and retention in the bone marrow .
Recombinant mouse SDF-1β is typically produced in Escherichia coli (E. coli) and is available as a sterile filtered white lyophilized (freeze-dried) powder . It is used primarily for research purposes and is not intended for human, animal, or diagnostic applications . For optimal stability, the lyophilized protein should be stored desiccated below -18°C. Upon reconstitution, it should be aliquoted and stored at the same temperature, with the addition of a carrier protein (0.1% HSA or BSA) for long-term storage .
