Presence of Ceramidase Activity in Electronegative LDL

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  • Núria Puig
  • Jose Rives
  • Estruch Alrich, Montserrat
  • Ana Aguilera-Simon
  • Noemi Rotllan
  • Mercedes Camacho
  • Núria Colomé
  • Francesc Canals
  • José Luis Sánchez-Quesada
  • Sonia Benitez

Electronegative low-density lipoprotein (LDL(−)) is a minor modified fraction of human plasma LDL with several atherogenic properties. Among them is increased bioactive lipid mediator content, such as lysophosphatidylcholine (LPC), non-esterified fatty acids (NEFA), ceramide (Cer), and sphingosine (Sph), which are related to the presence of some phospholipolytic activities, including platelet-activating factor acetylhydrolase (PAF-AH), phospholipase C (PLC), and sphingomyelinase (SMase), in LDL(−). However, these enzymes’ activities do not explain the increased Sph content, which typically derives from Cer degradation. In the present study, we analyzed the putative presence of ceramidase (CDase) activity, which could explain the increased Sph content. Thin layer chromatography (TLC) and lipidomic analysis showed that Cer, Sph, and NEFA spontaneously increased in LDL(−) incubated alone at 37 °C, in contrast with native LDL(+). An inhibitor of neutral CDase prevented the formation of Sph and, in turn, increased Cer content in LDL(−). In addition, LDL(−) efficiently degraded fluorescently labeled Cer (NBD-Cer) to form Sph and NEFA. These observations defend the existence of the CDase-like activity’s association with LDL(−). However, neither the proteomic analysis nor the Western blot detected the presence of an enzyme with known CDase activity. Further studies are thus warranted to define the origin of the CDase-like activity detected in LDL(−).

Original languageEnglish
Article number165
JournalInternational Journal of Molecular Sciences
Volume24
Number of pages13
ISSN1661-6596
DOIs
Publication statusPublished - 2023

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© 2022 by the authors.

    Research areas

  • ceramidase, ceramide, electronegative LDL, sphingomyelinase, sphingosine

ID: 335963029