Two novel missense variants altering cytosolic phospholipase A2α structural dynamics partially affect platelet signaling pathways associated with bleeding among Glanzmann thrombasthenia patients from two unrelated south Indian families

Cytosolic phospholipase A2 (cPLA2), encoded by PLA2G4A plays a crucial role in platelet activation through thromboxane A2 biosynthesis. Defects in this pathway can lead to bleeding disorders; however, the precise role of cPLA2 in Glanzmann thrombasthenia (GT) or GT-like syndromes remains poorly understood. The current study emerged from a fortuitous discovery of novel PLA2G4A variants, p.Asp455Val (D455V) and p.Glu119Lys (E119K), among 3 GT patients from two unrelated families in south India. We envisaged a hypothesis to identify a hitherto unknown role of cPLA2 that could be attributed to GT-like bleeding symptoms in these patients. An extensive computational workflow, including variant classification, conservation analysis, stability prediction, molecular docking, molecular dynamics simulations, principal component analysis, and binding free energy (MMPBSA) calculations, were employed to assess mutation-induced alterations in the cPLA2 protein. The current findings depicted that both variants affected conformational dynamics, ligand recognition patterns, and local interaction networks, without causing any drastic global structural destabilization. In particular, the D455V partially disrupted the catalytic domain, potentially reducing substrate (PAPC) stabilization and hampering interactions with catalytic products. Likewise, the E119K variant partially affected the C2 domain, potentially altered electrostatic interactions and enhanced regional flexibility, which may compromise product (AA) stabilization. Further analyses revealed mutation-induced changes in collective motions, protein-ligand interactions, solvent accessibility, and secondary structural elements. Overall, our findings promote the hypothesis that both E119K and D455V variants may partially alter phospholipid-associated interactions, and cPLA2-mediated downstream signaling. Moreover, this study underscores cPLA2 as a potential modifier of platelet function and bleeding severity.