Formation of membrane pores/channels regulates various cellular processes, such as necroptosis or stem cell niche signaling. However, the roles of membrane lipids in the formation of pores and their biological functions are largely unknown. Here, using the cellular stress model evoked by the sphingolipid analog drug FTY720, we show that formation of ceramide-enriched membrane pores, referred to here as ceramidosomes, is initiated by a receptor-interacting Ser/Thr kinase 1 (RIPK1)– ceramide complex transported to the plasma membrane by nonmuscle myosin IIA– dependent trafficking in human lung cancer cells. Molecular modeling/simulation coupled with site-directed mutagenesis revealed that Asp147 or Asn169 of RIPK1 are key for ceramide binding and that Arg258 or Leu293 residues are involved in the myosin IIA interaction, leading to ceramidosome formation and necroptosis. Moreover, generation of ceramidosomes independently of any external drug/stress stimuli was also detected in the plasma membrane of germ line stem cells in ovaries during the early stages of oogenesis in Drosophila melanogaster. Inhibition of ceramidosome formation via myosin IIA silencing limited germ line stem cell signaling and abrogated oogenesis. In conclusion, our findings indicate that the RIPK1– ceramide complex forms large membrane pores we named ceramidosomes. They further suggest that, in addition to their roles in stress-mediated necroptosis, these ceramide-enriched pores also regulate membrane integrity and signaling and might also play a role in D. melanogaster ovary development.
|Number of pages||18|
|Journal||Journal of Biological Chemistry|
|State||Published - Jan 11 2019|
Bibliographical noteFunding Information:
This research was supported in part by the Lipidomics, Cell, and Molecular Imaging and the Cell Evaluation and Therapy Shared Resources, Hollings Cancer Center, Medical University of South Carolina (P30 CA138313). This work was also supported by research grants from the National Institutes of Health (CA173687, CA088932, DE016572, and 1PO1 CA203628) and the SmartState Endowment in Lipidomics and Drug Discovery (to B. O.) and partially supported by the Notre Dame Integrated Imaging Facility (to K. A. J. and R. V. S.). B. O. is the founder and Chief Executive Officer of Lipo-Immuno Tech, LLC, and Z. M. S. is the director of synthetic chemistry of Lipo-Immuno Tech, LLC. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
© 2019 Nganga et al. Published under exclusive license by The American Society for Biochemistry and Molecular Biology, Inc.
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology