Human mouse mast cell protease 7-like tryptase genes are pseudogenes

Area of Science:

• Genetics
• Molecular Biology
• Immunology

Background:

• Alpha-tryptase and beta-tryptase are key indicators in mast cell disorders.
• A third tryptase gene family, human mouse mast cell protease 7 (hmMCP-7)-like tryptase, has been identified on chromosome 16.

Purpose of the Study:

• To investigate the expression of hmMCP-7-like tryptase genes in human mast cells.
• To determine if these novel tryptase genes are transcriptionally active.

Main Methods:

• Cloning and sequencing of a 2842-bp hmMCP-7-like tryptase gene from human placental genomic DNA.
• Utilizing Polymerase Chain Reaction (PCR) to detect gene presence and Reverse Transcription PCR (RT-PCR) to assess gene expression in various human mast cell samples and cell lines.

Main Results:

• The cloned gene was identified as hmMCP-7-like tryptase III, sharing high similarity with I and II.
• hmMCP-7-like tryptase genes were detected in the genomes of multiple human mast cell types and cell lines.
• RT-PCR analysis revealed no expression of hmMCP-7-like tryptases, while alpha- and beta-tryptases were expressed.

Conclusions:

• hmMCP-7-like tryptase genes (I, II, and III) are likely pseudogenes.
• The presence of these pseudogenes is unlikely to interfere with the clinical quantification of alpha- and beta-tryptases.