Ceramides are a family of waxy lipid molecules.
A ceramide is composed of sphingosine and a fatty acid.
It is found in high concentrations within the cell membrane of eukaryotic cells.
They are component lipids that make up sphingomyelin, one of the major lipids in the lipid bilayer.
Ceramide can regulate differentiation, proliferation, and programmed cell death of cells.
There are three major pathways of ceramide generation: sphingomyelinase pathway, de novo pathway, and the salvage pathway.
It is a bioactive lipid.
Its activity has been implicated: apoptosis, cell growth arrest, differentiation, cell senescence, cell migration and adhesion.
May play a role in a number of pathological states including cancer, neurodegeneration, diabetes, microbial pathogenesis, obesity, and inflammation.
Ceramides induce skeletal muscle insulin resistance.
They induce insulin resistance in many tissues.
They inhibit Akt/PKB signaling.
The aggregation of LDL cholesterol by ceramide causes LDL retention in arterial walls, leading to atherosclerosis.
It cause endothelial dysfunction by activating protein phosphatase 2.
It suppresses mitochondrial electron transport chain and induces production of reactive oxygen species.
Functions as a proapoptotic molecule.
Ceramide accumulation has been found following treatment of cells with a number of apoptotic agents including ionizing radiation, and chemotherapy.
It has apoptosis-inducing effects in cancer cells.
Ceramide has been termed the tumor suppressor lipid.
It is thought ceramide functions upstream of the mitochondria in inducing apoptosis, but the mechanism by which this lipid regulates apoptosis remains unproven.
It is the main component of the stratum corneum of the epidermis layer of human skin.
The stratum corneum is composed of 50% ceramides, 25% cholesterol, and 15% free fatty acids.
Ceramide, along with cholesterol and saturated fatty acids, create a water-impermeable, organ that prevents excessive water loss due to evaporation as well as a barrier against the entry of microorganisms.
In psoriasis the water permeability barrier is compromised.
Ceramide VI is the most abundant ceramide of the skin, along with ceramide II.
The extracellular lipid lamellae of the stratum corneum contains ultra long chain (C28-C36) ceramides.
With aging ceramide and cholesterol in the stratum corneum of humans decrease.
Increased ceramide synthesis leads to both leptin resistance and insulin resistance.
An elevated level of ceramide leads to insulin resistance.
Substances known to induce ceramide generation:
Anandamide
Ceramidase inhibitors
Chemotherapeutic agents
Fas ligand
Endotoxin
Homocysteine
Heat
Gamma interferon
Ionizing radiation
Matrix metalloproteinases
Niacinamide
Reactive oxygen species
Tetrahydrocannabinol and other cannabinoids
TNF-alpha
1,25 Dihydroxy vitamin D
It is hypothesized ceramide generated in the plasma membrane enhances membrane rigidity.
Ceramides are ingredients in some topical skin medications used to complement treatment for skin conditions such as eczema..
They are also used in cosmetic products such as some soaps, shampoos, skin creams, and sunscreens Ceramide is rarely found in bacteria.