Relevance of ceramide 1-phosphate domain formation in activation of cytosolic phospholipase A2

Abstract

Ceramide 1-phosphate (C1P), as a lipid mediator, specifically binds and activates cytosolic phospholipase A₂α (cPLA₂α). Previous findings revealed that modification of the specific hydrophobic moiety decreases the affinity with cPLA₂α. However, the possible biological role of the temporal C1P-enriched domains formed in biomembranes for the molecular recognition of cPLA₂α has not been fully elucidated. In this study we elucidated the properties of segregated domains formed by C1P (and its analogs) and the affinity of cPLA₂α for C1P in different co-lipid environments by fluorescence spectroscopy using trans-parinaric acid and surface plasmon resonance (SPR). Fluorescence measurements suggested that the formation of C1P ordered domains is strongly influenced by interfacial 3-OH and phosphate groups of C1P, such as hydrogen-bonding and electrostatic interactions, and depends on the co-lipid composition of the host bilayer. SPR indicated that C1P under the lipid environment favorable for the formation of C1P clusters has higher affinity for cPLA₂α. Thus, we speculate that C1P clusters formed under certain membrane conditions are important in specific binding with cPLA₂α by increasing the interaction between the C1P headgroup and basic residues of cPLA₂α. In conclusion, this study revealed that the local formation of lipid mediator-rich clusters in biomembranes likely has a significant effect on the interaction between the mediator and its receptor protein.