Robust cre-mediated recombination in small intestinal stem cells utilizing the olfm4 locus

Area of Science:

• Gastroenterology
• Developmental Biology
• Molecular Biology

Background:

• The small intestine epithelium is a highly regenerative tissue, crucial for nutrient absorption.
• Long-lived cycling stem cells, marked by Lgr5 expression, reside at the base of intestinal crypts.
• Existing Lgr5 reporter models have limitations in quantitative gene deletion due to variable expression.

Purpose of the Study:

• To develop a more effective genetic tool for studying Lgr5+ intestinal stem cells.
• To validate Olfactomedin-4 (Olfm4) as a reliable marker for these stem cells.
• To enable precise visualization and genetic manipulation of intestinal stem cells.

Main Methods:

• Generation of an Olfactomedin-4 (Olfm4)-IRES-eGFPCreERT2 knockin mouse model.
• Assessment of Olfm4 expression in relation to Lgr5+ stem cells.
• Evaluation of the Olfm4-driven eGFPCreERT2 fusion protein for marking and genetic induction.
• Utilizing a conditional LacZ reporter system to confirm CreERT2 activity.

Main Results:

• Olfactomedin-4 (Olfm4) is identified as a robust marker for murine small intestinal stem cells.
• The generated Olfm4-IRES-eGFPCreERT2 model effectively marks all Lgr5+ stem cells in the small intestine.
• The eGFPCreERT2 fusion protein demonstrates robust efficiency in activating conditional reporters.
• Olfm4 knockout animals exhibit no observable phenotype, suggesting functional redundancy or compensation.

Conclusions:

• The Olfm4-IRES-eGFPCreERT2 mouse model provides a superior tool for studying intestinal stem cells compared to previous Lgr5-based models.
• This new model facilitates accurate visualization and efficient genetic manipulation of Lgr5+ stem cells.
• Olfactomedin-4 (Olfm4) serves as a reliable marker for identifying and targeting intestinal stem cells for research.