Page "Lipid" Paragraph 21

In recent years, evidence has emerged showing that lipid signaling is a vital part of the cell signaling.

Lipid signaling may occur via activation of G protein-coupled or nuclear receptors, and members of several different lipid categories have been identified as signaling molecules and cellular messengers.

These include sphingosine-1-phosphate, a sphingolipid derived from ceramide that is a potent messenger molecule involved in regulating calcium mobilization, cell growth, and apoptosis ; diacylglycerol ( DAG ) and the phosphatidylinositol phosphates ( PIPs ), involved in calcium-mediated activation of protein kinase C ; the prostaglandins, which are one type of fatty-acid derived eicosanoid involved in inflammation and immunity ; the steroid hormones such as estrogen, testosterone and cortisol, which modulate a host of functions such as reproduction, metabolism and blood pressure ; and the oxysterols such as 25-hydroxy-cholesterol that are liver X receptor agonists.

Phosphatidylserine lipids are known to be involved in signaling for the phagocytosis of apoptotic cells and / or pieces of cells.

They accomplish this by being exposed to the extracellular face of the cell membrane after the inactivation of flippases which place them exclusively on the cytosolic side and the activation of scramblases, which scramble the orientation of the phospholipids.

After this occurs, other cells recognize the phosphatidylserines and phagocytosize the cells or cell fragments exposing them.