title: Ceramide-1-phosphate, a new mediator of development and survival in retina photoreceptors.
abstract: PURPOSE. Simple sphingolipids control crucial cellular processes in several cell types. Previous work demonstrated that sphingolipids, such as ceramide, sphingosine, and sphingosine-1-phosphate, are key mediators in the regulation of survival, differentiation, and proliferation of retina photoreceptors. Ceramide-1-phosphate (C1P) regulates growth and survival in several cell types; however, little is known concerning its functions in the retina. Whether C1P also participates in controlling photoreceptor development was also explored. METHODS. Rat retina neuronal cultures were supplemented with 1 to 10 μM C1P. Proliferation was determined by evaluating 5-bromo-2-deoxyuridine (BrdU) uptake and the number of mitotic figures and differentiation by evaluating opsin and peripherin expression by immunocytochemistry and Western blot. Apoptosis was inhibited with the pan caspase inhibitor ZVADFMK and evaluated by TUNEL assay, propidium iodide/annexin V, and DAPI labeling. Preservation of mitochondrial membrane potential was evaluated. RESULTS. C1P enhanced BrdU uptake and increased mitosis in retinal progenitors. C1P addition advanced photoreceptor differentiation, enhancing opsin and peripherin expression and stimulating development of the apical processes in which these proteins were concentrated. In the absence of these trophic factors, photoreceptors degenerated after 4 days in vitro, and at day 6, almost 50% of photoreceptors were apoptotic. C1P decreased photoreceptor apoptosis, reducing this percentage by half. Inhibiting caspase activity reduced photoreceptor apoptosis in the controls, but did not increase opsin expression, implying that C1P has separate effects on differentiation and survival. CONCLUSIONS. These results suggest for the first time that C1P is a novel mediator that has multiple functions in photoreceptors, initially regulating their proliferation and then promoting their survival and differentiation.
authors: Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Universidad Nacional del Sur (UNS), Buenos Aires, Argentina.
authors: Gisela E
authors: GE
authors: Miranda
authors: Carolina E
authors: CE
authors: Abrahan
authors: Daniela L
authors: DL
authors: Agnolazza
authors: Luis E
authors: LE
authors: Politi
authors: Nora P
authors: NP
authors: Rotstein
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002518:Ceramides / Q000494:pharmacology*; D019084:Fluorescent Antibody Technique, Indirect; D020287:In Situ Nick-End Labeling; D007381:Intermediate Filament Proteins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D008856:Microscopy, Fluorescence; D009419:Nerve Tissue Proteins / Q000378:metabolism; D055355:Opsins / Q000378:metabolism; D064531:Peripherins; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013234:Stem Cells / Q000187:drug effects* / Q000378:metabolism
chemical_list: D002518:Ceramides; D007381:Intermediate Filament Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D055355:Opsins; D064531:Peripherins; C065576:ceramide 1-phosphate