RESUMO
Gangliosides in rat pancreatic tissue and isolated pancreatic islets were examined by methods including glycolipid-overlay techniques. The content of gangliosides in isolated pancreatic islets was approximately 6-fold higher than that in pancreatic tissue when compared on a protein basis. While N-glycolylneuraminic acid amounted to 7.2% of total lipid-bound sialic acids of pancreatic tissue, this molecular species was not detected in that of pancreatic islets. A remarkable difference in ganglioside composition was observed between pancreatic tissue and pancreatic islets. Pancreatic tissue showed a complex ganglioside pattern with GM3 as the largest ganglioside component, whereas isolated pancreatic islets had a simpler ganglioside profile without detectable amounts of GM3 and some other components. Pancreatic gangliosides were further examined by thin-layer chromatographic immunostaining with a monoclonal antibody A2B5 that reacts specifically with c-series gangliosides. Pancreatic tissue and pancreatic islets showed almost identical ganglioside patterns consisting of GT3, GT2, GQ1c, and GP1c. The concentration of c-series gangliosides in pancreatic islets was calculated to be more than 250-fold higher than that of pancreatic tissue. These results shows that pancreatic islet cells have a distinct ganglioside composition in rat pancreas.
Assuntos
Gangliosídeos/análise , Ilhotas Pancreáticas/química , Pâncreas/química , Animais , Anticorpos Monoclonais/imunologia , Cromatografia em Camada Fina , Gangliosídeo G(M1)/análise , Gangliosídeo G(M1)/classificação , Gangliosídeo G(M1)/imunologia , Gangliosídeo G(M1)/metabolismo , Gangliosídeo G(M3)/análise , Gangliosídeo G(M3)/classificação , Gangliosídeo G(M3)/metabolismo , Gangliosídeos/classificação , Gangliosídeos/imunologia , Gangliosídeos/metabolismo , Glicolipídeos/metabolismo , Masculino , Ácido N-Acetilneuramínico/análise , Ácido N-Acetilneuramínico/metabolismo , Ácidos Neuramínicos/análise , Ácidos Neuramínicos/metabolismo , Neuraminidase/metabolismo , Pâncreas/citologia , Ratos , Ratos Sprague-DawleyRESUMO
Glucosylceramide, radiolabelled on the glucose residue, was administered to rats and the radioactive gangliosides formed at different time points were chemically characterized. They were identified as GM3, GM1, GD1a and GD1b, each one carrying only radioactive glucose. The time course of each individual ganglioside showed that the simpler gangliosides were formed earlier but were consumed earlier than the more complex ones, resulting in radioactivity patterns that were different at each time point. Only 30 h after injection did it resemble that of endogenous rat liver gangliosides. These results indicate that an extensive precursor-product relationship actually exists in the course of ganglioside biosynthesis.
Assuntos
Cerebrosídeos/farmacocinética , Gangliosídeos/biossíntese , Glucosilceramidas/farmacocinética , Fígado/metabolismo , Animais , Cromatografia Gasosa , Gangliosídeo G(M3)/análise , Gangliosídeo G(M3)/biossíntese , Gangliosídeo G(M3)/classificação , Gangliosídeos/análise , Gangliosídeos/classificação , Glucosilceramidas/análise , Fígado/análise , Masculino , Ratos , Ratos EndogâmicosRESUMO
The present study investigates the chemical structure of a ganglioside, detected by monoclonal antibody (MAb) MacG1, which reacts with intracytoplasmic granules of tumor-infiltrating macrophages. The results obtained by enzymatic hydrolysis and fast-atom bombardment-mass spectrometry reveal that MAb MacG1 reacts with a subcomponent of the ganglioside GM3 found in melanoma and bovine brain. MAb MacG1 might be a powerful tool to distinguish among GM3 species and could help to define their possibly different biological functions.
