Evolutionary conservation of P-selectin glycoprotein ligand-1 primary structure and function

Area of Science:

• Immunology
• Evolutionary Biology
• Glycobiology

Background:

• P-selectin glycoprotein ligand-1 (PSGL-1) mediates leukocyte recruitment to inflammatory sites.
• Core-2 O-glycosylation and tyrosine sulfation of PSGL-1 are essential for selectin binding.
• Limited data exists on the evolutionary conservation of PSGL-1 structure and selectin binding sites.

Purpose of the Study:

• To investigate the evolutionary conservation of PSGL-1 primary structure across 14 mammalian species.
• To examine the conservation of selectin binding sites on mammalian PSGL-1.
• To analyze the functional implications of PSGL-1 evolution on leukocyte recruitment.

Main Methods:

• Performed multiple sequence alignment of PSGL-1 amino acid sequences from 14 mammalian species.
• Analyzed conserved domains, including N-terminal regions, mucin-like domains, and transmembrane/cytoplasmic domains.
• Conducted functional assays using CHO cells and neutrophils to assess PSGL-1 interactions with human selectins.

Main Results:

• PSGL-1 N-terminus is poorly conserved, but tyrosine sulfation sites and core-2 O-glycosylation motifs are present in most species.
• Transmembrane and cytoplasmic domains, as well as moesin binding residues, are highly conserved.
• Functional assays demonstrated that while some mammalian PSGL-1 can bind selectins, efficiency varies, and tyrosine sulfation is critical for binding.

Conclusions:

• Mammalian PSGL-1 exhibits conserved transmembrane and cytoplasmic domains, and evolutionary conserved L- and P-selectin binding sites despite N-terminal sequence variability.
• Post-translational modifications, particularly tyrosine sulfation, play a critical role in regulating mammalian PSGL-1 interactions with selectins.
• Species-specific differences in PSGL-1 glycosylation and sulfation impact leukocyte recruitment efficiency.