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The recycling ceramide is a precursor of hypertonicity induced increase of glucosylceramide synthesis
Author(s) -
Pescio Lucila Gisele,
SterinSpeziale Norma Beatriz
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.lb260
Subject(s) - ceramide , ceramide synthase , chemistry , fumonisin b1 , biochemistry , de novo synthesis , serine , galactose , biosynthesis , metabolism , atp synthase , microbiology and biotechnology , stereochemistry , enzyme , biology , apoptosis , food science , mycotoxin
We have reported that hypertonicity induces MDCK cell differentiation by a GlucosylCeramide Synthase (GCS) dependent mechanism. Ceramide substrate can stem from the de novo synthesis or the recycling pathway. In this study we evaluate the involvement of both pathways in the hypertonicity induced increase of Glycosphingolipid (GSL) synthesis. Confluent MDCK cells were submitted to high NaCl concentration or kept under isotonicity. GSL metabolism was determined by using 14 C‐Galactose ( 14 C‐Gal) and 14 C‐Palmitic Acid ( 14 C‐PA) as radioactive precursors in the presence of Fumonisin B1 (FB1), a ceramide synthase inhibitor, or Cycloserine (CS), a serine palmitoiltransferase inhibitor. Under isotonic conditions, 14 C‐Gal/GlcCer formation was FB1/CS sensitive, while hipertonicity induced a 14 C‐Gal/GlcCer increase partially sensitive to FB1 but not to CS. In control cultures, 14 C‐Gal/GlcCer accounted for 23% of total GSLs formed, while 14 C‐PA/GlcCer represented 44% of total GSLs. Over 24h of hypertonicity, 14 C‐Gal/GlcCer synthesis increased to 43%, while 14 C‐PA/GlcCer levels decreased significantly. The results suggest that the pool of Cer involved in the hypertonicity induced MDCK cell differentiation comes from the recycling but not from de novo synthesis pathway. This work was supported by the University of Buenos Aires (UBACyT B068), CONICET (PIP 5557) and ANPCyT (PICT 33154) grants .