Dataset Information

Ceramide synthase-dependent ceramide generation and programmed cell death: involvement of salvage pathway in regulating postmitochondrial events.

ABSTRACT: The sphingolipid ceramide has been widely implicated in the regulation of programmed cell death or apoptosis. The accumulation of ceramide has been demonstrated in a wide variety of experimental models of apoptosis and in response to a myriad of stimuli and cellular stresses. However, the detailed mechanisms of its generation and regulatory role during apoptosis are poorly understood. We sought to determine the regulation and roles of ceramide production in a model of ultraviolet light-C (UV-C)-induced programmed cell death. We found that UV-C irradiation induces the accumulation of multiple sphingolipid species including ceramide, dihydroceramide, sphingomyelin, and hexosylceramide. Late ceramide generation was also found to be regulated by Bcl-xL, Bak, and caspases. Surprisingly, inhibition of de novo synthesis using myriocin or fumonisin B1 resulted in decreased overall cellular ceramide levels basally and in response to UV-C, but only fumonisin B1 inhibited cell death, suggesting the presence of a ceramide synthase (CerS)-dependent, sphingosine-derived pool of ceramide in regulating programmed cell death. We found that this pool did not regulate the mitochondrial pathway, but it did partially regulate activation of caspase-7 and, more importantly, was necessary for late plasma membrane permeabilization. Attempting to identify the CerS responsible for this effect, we found that combined knockdown of CerS5 and CerS6 was able to decrease long-chain ceramide accumulation and plasma membrane permeabilization. These data identify a novel role for CerS and the sphingosine salvage pathway in regulating membrane permeability in the execution phase of programmed cell death.

SUBMITTER: Mullen TD

PROVIDER: S-EPMC3091202 | biostudies-other | 2011 May

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Ceramide synthase-dependent ceramide generation and programmed cell death: involvement of salvage pathway in regulating postmitochondrial events.

Mullen Thomas D TD Jenkins Russell W RW Clarke Christopher J CJ Bielawski Jacek J Hannun Yusuf A YA Obeid Lina M LM

The Journal of biological chemistry 20110309 18

The sphingolipid ceramide has been widely implicated in the regulation of programmed cell death or apoptosis. The accumulation of ceramide has been demonstrated in a wide variety of experimental models of apoptosis and in response to a myriad of stimuli and cellular stresses. However, the detailed mechanisms of its generation and regulatory role during apoptosis are poorly understood. We sought to determine the regulation and roles of ceramide production in a model of ultraviolet light-C (UV-C)- ...[more]

PMID: 21388949

Similar Datasets

Project description:PCD is a highly organised process that is involved in development and in an organisms response to biotic stresses (toxins and avirulent pathogens) and abiotic stresses (such as temperature, water availability, etc.). It is a genetically regulated form of cellular suicide, however in plants the underlying process is poorly understood. Although PCD may occur in response to different stimuli; we believe once it is triggered, one core mechanism is responsible for the cellular demise. It is our aim to identify the elements of this mechanism. We will do this by expanding on the work of a previous user of GARNet's GeneChip microarray facility, Dr. Jodi Swidzinski. She utilised an Arabidopsis cell suspension system; performing microarray analysis on both senescing, and heat shock induced PCD samples. This resulted in data showing that a large number of genes were upregulated (or downregulated) in response to both treatments. We are working under the premise that some of the genes that were similarly regulated under both treatments must be core PCD genes. However because of the large amount of data generated it is difficult to choose appropriate candidate genes (with any degree of confidence that they are core genes) for further study. We propose to use a third PCD-inducing treatment, involving a mycotoxin, to generate another population of microarray results. The mycotoxin we intend to use is Fumonisin B1 (FB1). This is an extremely potent compound that induces PCD by disrupting ceramide synthesis. We have found Arabidopsis protoplasts to be much more sensitive than cells to the toxin at low concentrations. Protoplasts are treated with 20mM FB1 and RNA is extracted at time points when 0%, 20% and 40% of protoplasts have died. This RNA is then pooled. RNA from methanol treated protoplasts is used as a control. We intend for these RNA samples to be subjected to GeneChip microarray analysis. This would identify genes differentially regulated due to FB1 treatment, which would be interesting in itself. However, by combining this data with that from previous work by Swidzinski (2002) we will be able to decrease the pool of possible core genes further, and increase the chances of selecting an appropriate candidate gene. This will both improve upon existing work and add value to an existing GARNet data set. Experimenter name = Mark Diamond Experimenter phone = 017162251 Experimenter fax = 017161153 Experimenter address = Botany Department Experimenter address = University College Dublin Experimenter address = Belfield Experimenter zip/postal_code = Dublin 4 Experimenter country = Ireland Keywords: compound_treatment_design

Project description:A major pathophysiologic mechanism in sepsis is impaired host immunity which results in failure to eradicate invading pathogens and increased susceptibility to secondary infections. Although many immunosuppressive mechanisms exist, increased expression of the inhibitory receptor programmed cell death 1 (PD-1) and its ligand (PD-L1) are thought to play key roles. The newly recognized phenomenon of T cell exhaustion is mediated in part by PD-1 effects on T cells. This study tested the ability of anti-PD-1 and anti-PD-L1 antibodies to prevent apoptosis and improve lymphocyte function in septic patients.Blood was obtained from 43 septic and 15 non-septic critically-ill patients. Effects of anti-PD-1, anti-PD-L1, or isotype-control antibody on lymphocyte apoptosis and interferon gamma (IFN-?) and interleukin-2 (IL-2) production were quantitated by flow cytometry.Lymphocytes from septic patients produced decreased IFN-? and IL-2 and had increased CD8 T cell expression of PD-1 and decreased PD-L1 expression compared to non-septic patients (P<0.05). Monocytes from septic patients had increased PD-L1 and decreased HLA-DR expression compared to non-septic patients (P<0.01). CD8 T cell expression of PD-1 increased over time in ICU as PD-L1, IFN-?, and IL2 decreased. In addition, donors with the highest CD8 PD-1 expression together with the lowest CD8 PD-L1 expression also had lower levels of HLA-DR expression in monocytes, and an increased rate of secondary infections, suggestive of a more immune exhausted phenotype. Treatment of cells from septic patients with anti-PD-1 or anti-PD-L1 antibody decreased apoptosis and increased IFN-? and IL-2 production in septic patients; (P<0.01). The percentage of CD4 T cells that were PD-1 positive correlated with the degree of cellular apoptosis (P<0.01).In vitro blockade of the PD-1:PD-L1 pathway decreases apoptosis and improves immune cell function in septic patients. The current results together with multiple positive studies of anti-PD-1 and anti-PD-L1 in animal models of bacterial and fungal infections and the relative safety profile of anti-PD-1/anti-PD-L1 in human oncology trials to date strongly support the initiation of clinical trials testing these antibodies in sepsis, a disorder with a high mortality.

Dataset Information

Ceramide synthase-dependent ceramide generation and programmed cell death: involvement of salvage pathway in regulating postmitochondrial events.

Publications

Ceramide synthase-dependent ceramide generation and programmed cell death: involvement of salvage pathway in regulating postmitochondrial events.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets