![]() ![]() Differences in lipid droplet size may account for differences in lipid dynamics and be relevant to understand lipid overload diseases.ĬonclusionĪctivity of the Kennedy pathway regulates the balance between phospholipids and neutral lipids, while the Lands cycle regulates lipid droplet size by regulating surface availability and influencing surface to volume ratio.įurthermore we demonstrate that modulation of the LD pool by LPCAT1 influences the release of lipoprotein from liver cells. Lipids are important components of cells, with a function in cellular structure, regulation, signaling and as energy source, in particular neutral lipids. The cellular location of storage of neutral lipid is the lipid droplet (LD). LDs consist of a core of neutral lipids that is surrounded by a monolayer of phospholipids, mainly phosphatidylcholine. Different proteins are associated with the LDs, including several enzymes of lipid metabolism. Many metabolic disorders like diabetes and cardiovascular diseases are associated with defects in lipid metabolism and derive from additive defects in different pathways, often described as metabolic syndrome that can gradually progress into more severe diseases. The first step is usually the excess storage of lipids within different body tissues resulting in the development of obesity. Therefore, it is crucial to understand how the storage of lipids is regulated under normal conditions. Lipids are in a constant flux and are continuously converted into each other. Within cells they can move within membranes and between different cellular compartments. Extracellularly, the bulk of lipids is transported in lipoproteins.įurthermore, lipids are exchanged between different tissues. These lipoproteins are soluble complexes of proteins (apolipoproteins) and lipids that are transported in the circulation of vertebrates and insects and that are synthesized in the liver and intestine. They are classified into chylomicrons (CM), very low density (VLDL), low density (LDL) and high density (HDL) lipoproteins based on their apolipoprotein component and their density, which is determined by the lipid composition. The major neutral lipid, triacylglycerol (TAG), is secreted from the liver and intestine in apolipoproteinB (apoB) containing lipoproteins (CM and VLDL). In contrast to other apolipoproteins, apoB is not exchangeable between lipoproteins and resides in the plasma in a lipid-associated form only. While VLDL and CM contain apoE, apoC and apoB, LDL harbors exclusively apoB. In the absence of loaded lipids apoB cannot be secreted and is rapidly degraded. The TAG secreted as CM and VLDL mainly derives from TAG stored in cytosolic LDs. ĭepending on cell type, nutritional status and developmental state the LD pool can vary in droplet number, size and localization within short time scales. The growth of LDs and the incorporation of FAs into TAG is a fast event, typically taking just a few minutes. Once formed, lipid droplets can fuse with each other or transfer material by a slow coalescence event. DENSITOMETRY WAS DONE WITH IMAGEJ SOFTWARE PC. ![]()
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