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Updated: Aug 6, 2026
A Novel in vivo Gene Transfer Technique and in vitro Cell Based Assays for the Study of Bone Loss in Musculoskeletal Disorders
Published on: June 8, 2014
Targeted expression of Cre recombinase in macrophages and osteoclasts in transgenic mice
Abstract:
To develop specific conditional gene ablation in the hematopoietic myeloid-osteoclast lineage, transgenic mice expressing Cre recombinase under the control of the CD11b promotor were generated on the C57BL/6 background. The cellular specificity of Cre activity following recombination was quantified in the Z/EG reporter transgenic mice by FACS analysis with lineage-specific markers and EGFP coexpression. A high degree of recombination, as evidenced by EGFP-positive cells, was demonstrated in macrophages and granulocytes of bone marrow and spleen by the presence of double-positive cells CD11b/EGFP and Gr1/EGFP, respectively. Interestingly, the peritoneal macrophage population showed almost complete DNA recombination at large. Most important, mature osteoclast cells derived from the double transgenic bone marrow and spleen progenitors were EGFP-positive. Hence, these CD11b-Cre mice will provide a unique tool to unravel novel gene function and activities involved during osteoclast and macrophage differentiation and maturation processes.
Insights
New CD11b-Cre transgenic mice enable targeted gene deletion in myeloid and osteoclast cells. This tool aids research into macrophage and osteoclast development and function.
Area of Science:
- Immunology
- Developmental Biology
- Genetics
Background:
- Conditional gene ablation is crucial for studying specific cell lineages.
- The CD11b promoter is expressed in myeloid cells, including macrophages and osteoclasts.
- A reliable Cre-lox system is needed to target these cells specifically.
Purpose of the Study:
- To generate and validate transgenic mice for conditional gene ablation in the hematopoietic myeloid-osteoclast lineage.
- To assess the cellular specificity and efficiency of Cre recombinase activity driven by the CD11b promoter.
- To establish a tool for investigating gene functions in osteoclast and macrophage biology.
Main Methods:
- Generation of CD11b-Cre transgenic mice on a C57BL/6 background.
- Crossbreeding with Z/EG reporter mice to visualize Cre activity via EGFP expression.
- Flow cytometry (FACS) analysis using lineage-specific markers (CD11b, Gr1) and EGFP coexpression.
- Assessment of recombination in bone marrow, spleen, and peritoneal cells.
Main Results:
- High Cre-mediated recombination, indicated by EGFP expression, was observed in macrophages and granulocytes.
- Bone marrow and spleen progenitors showed significant EGFP coexpression with CD11b and Gr1 markers.
- Peritoneal macrophages exhibited nearly complete DNA recombination.
- Mature osteoclasts derived from double transgenic progenitors were EGFP-positive, confirming lineage-specific targeting.
Conclusions:
- The generated CD11b-Cre transgenic mice demonstrate specific and efficient gene ablation in the myeloid-osteoclast lineage.
- These mice serve as a valuable tool for studying the roles of specific genes in macrophage and osteoclast differentiation and function.
- This model will advance research into the complex processes of bone remodeling and immune cell development.
