ReviewBiochemistry of very-long-chain and long-chain ceramides in cystic fibrosis and other diseases: The importance of side chain
Section snippets
Abreviations
C1P Ceramide-1-Phosphate Cerk Ceramide kinase Cers Ceramide synthases Cert Ceramide transfer protein CF Cystic Fibrosis CFTR Cystic Fibrosis Transmembrane Regulator Cptp C1P transport protein Degs Sphingolipid delta(4)-desaturases DRMs Detergent Resistant Membranes ELISA Enzyme-Linked Immunosorbent Assay ER Endoplasmic Reticulum FABP Fatty Acid Binding Protein Fapp2 Four-phosphate adaptor protein 2 FEV1 Forced expiratory volume in one second fln flincher Gba Glucosylceramidase GM1, GD1a, GD1b, and GT1b
Cystic fibrosis
Cystic fibrosis is the most common genetic disease in Caucasians with an incidence of 1 in 3000 births in Western countries [1]. Even though it was first described back in 1936 and 1938 by Fanconi and Andersen respectively [2,3], it was not until 1989 that an underlying genetic defect in cystic fibrosis transmembrane regulator (CFTR) was discovered by Francis Collins and Lap-Chee Tsui [4,5].This discovery laid ground for all future investigations of cystic fibrosis. CFTR gene, located at the
Metabolism of sphingolipids
In the late 19th century, JWL Tudichum was the first to recognize the enigmatic nature of a brain lipid that he isolated and named it “sphingosine” after the Sphinx, a creature from Greek mythology that devoured all the passengers who could not answer the riddle it was posing to them [24]. Indeed, sphingosine, an amino-alcohol of 18 carbons, and its relatives known as sphingolipids continue to present an enigma to all of us studying them to this day. Biochemical steps in the synthesis of
Metabolic actions of ceramides
Ceramides have long been known to be ubiquitous building blocks of eukaryotic cell membranes and signaling molecules produced mostly upon various exogenous stimuli like inflammation or stress. Therefore, the roles of ceramides in the cell can be view as structural components of the cellular membranes and as metabolic/bioactive, as the signaling molecules produced upon various stimuli.
Despite their involvement in numerous biological processes, remarkably little mechanistic insight has been
Ceramides as structural elements of biological membranes
The mechanistic basis and the biochemical pathways behind the phenotypes seen in the ceramide synthases knockout mice have not been fully explored yet. Part of the answer to these questions seems to lie in the structural role of ceramides as the fundamental building blocks of all eukaryotic cell membranes.
Ceramides form the intramembraneous backbone of all sphingolipids, including sphingomyelins. Sphingomyelins consist of phosphocholine or phosphoethanolamine bound to a ceramide backbone
Ceramides in CF
The first connection between ceramides and pulmonary infection with P. aeruginosa, the most common pathogen in the lungs in CF patients, was made by the group of Richard Blumberg. In their study, Neiuwenhuis and colleagues treated imunodeficient CD1d −/− mice with (2S, 3S, 4R)-1-O-(α-D-Galactosyl)-N-hexacosanoyl-2-amino-1,3,4-octadecanetriol (shortly named KRN7000), a compound similar to the naturally occurring α-galactosylceramide which is a ligand that activates NK cells and macrophages when
Ceramides and CFTR
CFTR is a large, intrinsically disordered protein [99] that is primarily localized at the apical domain of epithelial cells [100]. Each CFTR molecule contains two membrane –spanning domains (MSD1 and MSD2), two nucleotide binding domains that participate in ATP binding and hydrolysis (NBD1 and NBD2), and a regulatory domain (R) whose phosphorylation by protein kinase A (PKA) regulates opening of the channel [101]. The folding of the wild-type CFTR protein is slow and relatively inefficient due
Technical challenges in ceramide quantification
Much of the confusion in the current literature about the role of ceramides in health and disease arises from the flaws in the methods used for their quantification. Traditionally, ceramides have been quantified in biological samples using antibodies and mass spectroscopy. The results obtained from these studies sometimes led to fundamentally different conclusions [93,95].
In our previous work, we utilized 15B4 anti-ceramide monoclonal antibody from Sigma to quantify the total ceramide levels in
Conclusion
The sphingolipids family have been widely investigated for their role as structural and functional physiologically active molecules, yet their role still remains a riddle that fully justifies their name to this day. Ceramides, the basic building blocks of all sphingolipids, are important molecules in the physiology of lungs, with implications for diseases like cystic fibrosis. Intricacies in their structures, especially the length of their side acyl chain, seem to play previously unappreciated
Supplement
The mixture of 25 μl of brain lipid extract in chloroform (Avanti 131101C), subjected to thin-layer chromatography on the silica plate, and transferred to nytran membrane by diffusion. After separation on silica gel, standards were visualized after 30 min incubation in iodine vapor.
The Fig. 8B illustrates comparison of the binding of polyclonal and monoclonal antibodies against ceramides mixture commercially available from Sigma and Glycobiotech to various species of ceramides. Commercially
Acknowledgements
We want to acknowledge financial support from Canadian Institutes of Health Research (POP90155, account 6071), Canadian Cystic Fibrosis Foundation via McGill University (account 3645), Department for Administration and Development project, Ministry of Education, Youth and Sport, Czech Republic, Molecular and Cellular Clinical Approach to Healthy Ageing (ENOCH project) via IMTM (#869/V19).
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