TNF-α-mediated apoptosis is initiated in caveolae-like domains

Young Gyu Ko, Jae Seon Lee, Young Sun Kang, Jung Hyuck Ahn, Jeong Sun Seo

Research output: Contribution to journalArticlepeer-review

127 Citations (Scopus)

Abstract

Caveolae-like domains (CLDs) have been hypothesized to mediate apoptosis, since they contain sphingomyelin and initiate the conversion of sphingomyelin to ceramide. To address whether CLDs are directly involved in apoptosis, CLDs from U937 cells were isolated, taking advantage of their detergent insolubility and low density. The CLDs contained alkaline phosphatase as well as many signaling molecules, including Fyn, protein kinase Cα, Raf-1, phospholipase Cγ1, and tyrosine phosphoproteins. Immunoblotting and immunofluorescent data showed that TNF receptor 1 colocalized with CD36 in CLDs, suggesting that TNF-α-initiated apoptosis occurs in CLDs. When cells were incubated with lipoprotein-deficient medium, the cholesterol concentration was greatly decreased in CLDs but not in other fractions, implying that the CLDs were selectively disrupted. In the CLD- disrupted cells, the surface expression of TNF receptor 1 and CD36 was significantly reduced. Analysis of cellular morphology, percent DNA fragmentation, DNA laddering, and caspase-3 activity showed that TNF-α- mediated apoptosis was blocked in CLD-disrupted cells, whereas anti-Fas- mediated apoptosis was not. Since Fas was not found in CLDs of Jurkat cells, apoptosis by Fas ligation might not require CLDs. Taken together, these data strongly imply that TNF-α-mediated apoptosis is initiated in CLDs.

Original languageEnglish
Pages (from-to)7217-7223
Number of pages7
JournalJournal of Immunology
Volume162
Issue number12
Publication statusPublished - 1999 Jun 15
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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