A C-type lectin from the tunicate, Styela plicata, that modulates cellular activity

Area of Science:

• Immunology
• Marine Biology
• Biochemistry

Background:

• Tunicates, invertebrate chordates, possess proteins with properties similar to mammalian inflammatory cytokine interleukin 1 (IL-1).
• Understanding these homologous proteins can provide insights into conserved immune mechanisms across species.

Purpose of the Study:

• To characterize a specific protein from Styela plicata with potential IL-1-like activity.
• To investigate the functional effects of this tunicate protein on both tunicate and mammalian immune cells.
• To explore the molecular basis of its interaction with mammalian immune cells.

Main Methods:

• Characterization of a protein isolated from the tunicate Styela plicata.
• Assays to measure cell proliferation in tunicate and mammalian cells.
• Functional assays including phagocytosis activation, interleukin 2 (IL-2) secretion, and IL-2 receptor (IL-2R) expression.
• Partial amino acid sequencing and comparison with known lectin sequences.

Main Results:

• The Styela plicata protein stimulates proliferation in both tunicate and mammalian cells.
• It activates phagocytosis, increases IL-2 secretion by mammalian peripheral blood mononuclear cells, and enhances IL-2 receptor expression on EL-4.IL-2 cells.
• Amino acid sequence analysis reveals similarity to C-type lectins, specifically TC14 family members, suggesting a role in carbohydrate recognition.

Conclusions:

• The characterized Styela plicata protein exhibits IL-1-like immune-modulating functions.
• Its structural similarity to C-type lectins suggests it may interact with glycosylated cell surface receptors on mammalian immunocompetent cells.
• This finding highlights conserved immune pathways and the potential of invertebrate-derived molecules in understanding mammalian immunity.