Phospholipase Activity In Cells Research Articles

Characterization of the membrane interactions of phospholipase Cγ reveals key features of the active enzyme.

PLCγ enzymes are autoinhibited in resting cells and form key components of intracellular signaling that are also linked to disease development. Insights into physiological and aberrant activation of PLCγ require understanding of an active, membrane-bound form, which can hydrolyze inositol-lipid substrates. Here, we demonstrate that PLCγ1 cannot bind membranes unless the autoinhibition is disrupted. Through extensive molecular dynamics simulations and experimental evidence, we characterize membrane binding by the catalytic core domains and reveal previously unknown sites of lipid interaction. The identified sites act in synergy, overlap with autoinhibitory interfaces, and are shown to be critical for the phospholipase activity in cells. This work provides direct evidence that PLCγ1 is inhibited through obstruction of its membrane-binding surfaces by the regulatory region and that activation must shift PLCγ1 to a conformation competent for membrane binding. Knowledge of the critical sites of membrane interaction extends the mechanistic framework for activation, dysregulation, and therapeutic intervention.

A linker approach to phospholipopeptides

Peptides and phospholipids are important macromolecules in both the chemistry and biology fields, but phospholipopeptides are barely found in nature and have not been studied. Here, we report a novel and efficient approach to the synthesis of phospholipidpeptides. By utilizing cross‐linkers, phospholipopeptides from peptides with varied sequences and lengths were produced from phosphatidylethanolamine at high (>90%) yield, mild conditions and good applied scopes for multiple substrates. Synthetic phospholipopeptides containing bioactive peptide sequences may serve as therapeutics for a wide range of biomedical applications.Practical applications: Phospholipopeptides are prone to hydrolysis by the endogenous phospholipase activity in cells. Synthetic phospholipopeptides containing a bioactive peptide sequences may serve as therapeutics for a wide range of biomedical applications.Cysteine‐containing peptides of varied sequences and lengths were linked to the heads of phosphatidylethanolamine through the amino group to form phospholipopeptides.

A23187 and protein kinase c activators stimulate phosphatidylinositol metabolism and prostaglandin synthesis in a human lung cancer cell line

Activation of cell phospholipase, release of arachidonic acid and stimulation of prostaglandin synthesis were studied in a newly described human tumor cell line (Lu-65). In the Lu-65 tumor cell line, the calcium ionophore A23187 (2 microM) caused a 100% increase in the release of 3H-arachidonic acid and a 7-fold increase in the synthesis of prostaglandin E2. 1-oleoyl, -2-acetyl-glycerol (100 microM) increased arachidonate release and prostaglandin E2 synthesis by 100%. A23187 and the protein kinase C activators, 1,2-dioctanoyl-glycerol and 1-oleoyl, -2-acetyl-glycerol, decreased the specific radioactivity of 3H-arachidonate in phosphatidylinositol by 37% and 57%, respectively. The effects of A23187 were blocked in Ca2+-free media or in the presence of the phospholipase A2 inhibitor, p-bromophenacyl bromide, while those of 1-oleoyl, -2-acetyl-glycerol were not. The data provide evidence in a human tumor cell line for calcium/phospholipase A2-dependent and independent pathways for arachidonic acid release, both of which preferentially hydrolyze phosphatidylinositol.