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C 16 ‐Ceramide directly binds and activates p53 in response to cellular stress
Author(s) -
Jeffries Kristen,
Krupenko Natalia
Publication year - 2019
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.2019.33.1_supplement.lb274
Subject(s) - ceramide , microbiology and biotechnology , lipid signaling , gene silencing , apoptosis , regulator , chemistry , biology , biochemistry , receptor , gene
Ceramide is a key bioeffector in cellular adaptation to stress, and increased ceramide generation often functions as a pro‐apoptotic signal. Another key mediator of apoptosis, the p53 tumor suppressor protein, responds to diverse stress stimuli through its role as a transcription factor. We observed that folate withdrawal leads to CerS6 up‐regulation and C 16 ‐ceramide accumulation in a p53‐dependent manner as a pro‐apoptotic cue, and hypothesized that p53 activation could result from the direct binding of C 16 ‐ceramide to p53, which disrupts the protein interaction with its negative regulator, MDM2. Pulldown with biotinylated C 16 ‐ceramide and membrane binding assays confirmed that p53 binds C 16 ‐ceramide with high affinity and selectivity towards ceramide acyl chain length. In agreement, C 16 ‐ceramide treatment of cultured cells disrupted the interaction between MDM2 and p53 in bimolecular fluorescence complementation experiments. The physiological relevance of this mechanism of p53 activation was demonstrated in serum starved cells where CerS6‐dependent C 16 ‐ceramide generation mediated the stress response. Strikingly, the siRNA silencing of CerS6 prevented both p53 and p21 accumulation in response to serum starvation and partially rescued cells from G0/G1 arrest. These findings establish C 16 ‐ceramide as the first physiologic metabolite activating p53 through the direct binding to the protein. Future experiments will determine the mechanism for the loading of C 16 ‐ceramide onto p53 in cellular stress response. Support or Funding Information NIH CA193782‐01 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .