원형질막에서 약한 막결합부위와 PI(4,5)P₂결합에 의한 Membrane Blebbing 형성

Abstract

Plasma membrane blebs are dynamic cellular cytoskeleton remodeling events involved in apoptosis and cell movement. Phosphoinositide (PI) is one of the phospholipid components within inner leaflet of the plasma membrane, but the contribution of PI on membrane blebbing remains elusive. Here, we found that if the phosphatidylinositol-4-phosphate (PI4P)-specific binding pleckstrin homology (PH) domain of various proteins including OSBP, OSH1, or OSH2 was combined with the N-terminal hydrophobic domain of Aplysia phosphodiesterase 4 short-form (S(N30)), membrane blebbing occurred on the plasma membrane. However, unexpectedly, this membrane blebbing was mediated by phosphatidylinositol 4,5-bisphosphate (PI(4,5)P₂) binding rather than PI4P binding. To further elucidate this, we combined S(N30) with selective PI(4,5)P₂ binding PLCδ1 PH domain (S(N30)-GFP-PH(PLCδ1)), selective phosphatidylinositol 3,4,5-bisphosphate (PI(3,4,5)P₃) binding AKT1 PH domain (S(N30)-GFP-PH(AKT1)), or selective PS binding Lact-C2 domain (S(N30)-GFP-Lact-C2). Interestingly, overexpression of S(N30)-GFP-PH(PLCδ1) but not S(N30)-GFP-PH(AKT1) or S(N30)-GFP-Lact-C2 could strongly induce membrane blebbing. Our results clearly indicate that impairment of PI(4,5)P₂ binding in the plasma membrane is associated with cellular process of the plasma membrane blebbing.