C16-ceramide is a natural regulatory ligand of p53 in cellular stress response

Abstract

Ceramides are important participants of signal transduction, regulating fundamental cellular processes. Here we report the mechanism for activation of p53 tumor suppressor by C16-ceramide. C16-ceramide tightly binds within the p53 DNA-binding domain (Kd ~ 60 nM), in close vicinity to the Box V motif. This interaction is highly selective toward the ceramide acyl chain length with its C10 atom being proximal to Ser240 and Ser241. Ceramide binding stabilizes p53 and disrupts its complex with E3 ligase MDM2 leading to the p53 accumulation, nuclear translocation and activation of the downstream targets. This mechanism of p53 activation is fundamentally different from the canonical p53 regulation through protein–protein interactions or posttranslational modifications. The discovered mechanism is triggered by serum or folate deprivation implicating it in the cellular response to nutrient/metabolic stress. Our study establishes C16-ceramide as a natural small molecule activating p53 through the direct binding.

Oncometabolites in cancer aggressiveness and tumour repopulation

“…Indeed, C16‐ceramide can bind p53 causing disruption of the p53‐mouse double minute 2 homolog (MDM2) complex and reduction of p53 ubiquitination, thus leading to p53 accumulation as a cellular response to various cellular stresses. Interestingly, ceramide synthase knock‐down prevents p53 accumulation and the induction of its target genes (Fekry et al , ).…”

The Glyco-enzyme adaptor GOLPH3 Links Intra-Golgi Transport Dynamics to Glycosylation Patterns and Cell Proliferation

“…In our cell models, the globo pathway is prevalent; and we indeed find that GOLPH3 induces growth through effects on the globo series GSLs. Although the precise mechanism by which they exert their effects remains to be determined, Gb3 and the downstream metabolites Gb4, and sialo-Gb5 have been shown to cluster in GSL rich domains at focal adhesions (Steelant et al, 2002), where they bind to and activate integrins and RTK receptors to promote PI3K-Akt-mTOR signaling (Chuang et al, 2019;Furukawa et al, 2019;Hakomori Si, 2002;Park et al, 2012;Steelant et al, 2002;Wegner et al, 2018). An additional contributing factor to the pro-growth effects of GOLPH3 that is independent of GSL pathway being affected, is the decrease of Cer, a characterized tumor suppressor and inhibitor of cell proliferation (Hannun and Obeid, 2008;Reynolds et al, 2004).…”

“…Steady-state mass spectrometry and cytofluorimetric measurements (using ShtxB and Cholera toxin B fragment (ChTxB) (Gill and King, 1975;Jacewicz et al, 1986;Russo et al, 2018) evaluate the PM levels of Gb3 and GM1, respectively) were in agreement with the pulse-chase data. GOLPH3 OE increased the levels of Gb3 (though not those of GM1), and reduced the levels of Cer [in particular of the bioactive C16:0 Cer; (Fekry et al, 2018;Kroesen et al, 2001)] (Fig. 4B-D and Fig.…”

“…In sum, GOLPH3 plays a necessary though not exclusive role in the Golgi retention of several glyco-enzymes through binding to the DGB motif in their cytosolic tails. Here, we focus on the GSL metabolic GOLPH3 client enzymes as several GSL metabolites possess growth-promoting bioactivity and might play a role in the oncogenic activity of GOLPH3 (Canals and Hannun, 2013;Furukawa et al, 2019;Morad and Cabot, 2013).…”

Lipidomics needs more standardization

“…Lipid species in membranes act not as single molecules but as a collective which needs to be analyzed quantitatively and comprehensively to understand their biological function. Examples of bioactive lipid species include typical membrane lipids, such as ceramide (Cer) d18:1/16:0 as a selective natural ligand of p53 4 , or fatty acid-derived pro-inflammatory (i.e. prostaglandins, leukotrienes) and anti-inflammatory (i.e.…”