Selective reporter expression in mast cells using a chymase promoter

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• Primate alpha-chymases are mast cell proteases regulating peptides like angiotensin II.
• Animal models are essential for studying primate chymase in vivo due to enzyme specificity.
• Mast cell-specific promoters are needed to express active primate chymase in models.

Purpose of the Study:

• To identify and characterize a mast cell-specific promoter from the baboon chymase gene.
• To enable the development of transgenic mouse models for studying primate chymase function.
• To investigate the regulatory elements within the baboon chymase promoter.

Main Methods:

• Cloning the 571-bp 5'-upstream sequence of the baboon chymase gene linked to the lacZ gene.
• Generating transgenic mice to assess beta-galactosidase expression in mast cells.
• Utilizing a mouse mast cell line (JKras) for in vitro transcription studies.
• Analyzing cis-regulatory motifs, specifically a GATA motif, within the promoter sequence.

Main Results:

• The baboon chymase promoter successfully targeted beta-galactosidase expression to mast cells in transgenic mice.
• Transgene expression patterns mirrored endogenous mouse alpha-chymase expression.
• The JKras mast cell line selectively supported transgene expression.
• In vitro studies identified a critical GATA cis-regulatory motif essential for mast cell-specific promoter activity.

Conclusions:

• The 571-bp baboon chymase promoter contains essential elements for mast cell-specific expression.
• This promoter is the first described to direct transgene expression specifically to mouse mast cells.
• The promoter offers broad applicability for expressing mast cell regulatory proteins in vivo.