Sequence and expression of a rat cDNA for LECAM-1

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• LECAM-1 (Leukocyte Endothelial Cell Adhesion Molecule 1) is a key adhesion molecule involved in immune cell trafficking.
• Understanding the molecular structure and function of LECAM-1 across species is crucial for immunology research.

Purpose of the Study:

• To isolate and characterize a rat cDNA clone encoding the adhesion molecule LECAM-1.
• To determine the nucleotide sequence and predict the amino acid sequence and domain structure of rat LECAM-1.
• To investigate the expression patterns and functional interactions of rat LECAM-1.

Main Methods:

• cDNA cloning and sequencing from Sprague-Dawley (SD) rats.
• Bioinformatic analysis to predict protein domains and sequence identity with mouse and human orthologs.
• Northern blot analysis to detect transcript expression in various tissues and cell types.
• Functional expression studies in gp90MEL-14 negative mouse EL-4 cells to assess protein interactions.

Main Results:

• A partial rat cDNA clone encoding LECAM-1 (372 amino acids) was isolated, featuring lectin, EGF-like, and complement regulatory (CR) domains.
• High amino acid identity was observed between rat LECAM-1 domains and their mouse and human counterparts (e.g., lectin domain: 93.2% identity with mouse, 81.4% with human).
• Northern blot analysis revealed a ~3 kb transcript in peripheral blood mononuclear cells (PBMC), spleen, and thymus, with down-regulated expression upon mitogen stimulation of T cells. The expressed protein interacted with PPME.

Conclusions:

• The isolated rat LECAM-1 cDNA provides a valuable tool for studying immune cell adhesion and trafficking in rats.
• The conserved domain structure and sequence identity suggest functional conservation of LECAM-1 across mammals.
• Expression patterns indicate a role for LECAM-1 in immune surveillance and T cell activation, with potential modulation by mitogenic stimuli.