Ceramide phosphoethanolamine synthase SMSr is a target of caspase-6 during apoptotic cell death

The Metabolic Impact of Two Different Parenteral Nutrition Lipid Emulsions in Children after Hematopoietic Stem Cell Transplantation: A Lipidomics Investigation

Hematopoietic stem cell transplantation (HSCT) involves the infusion of either bone marrow or blood cells preceded by toxic chemotherapy. However, there is little knowledge about the clinical benefits of parenteral nutrition (PN) in patients receiving high-dose chemotherapy during HSCT. We investigated the lipidomic profile of plasma and the targeted fatty acid profiles of plasma and erythrocytes in children after HSCT using PN with either a fish oil-based lipid emulsion or a classic soybean oil emulsion. An untargeted liquid chromatography high-resolution mass spectrometry platform connected with a novel in silico annotation algorithm was utilized to determine the most relevant chemical subclasses affected. In addition, we explored the interrelation between the lipidomics profile in plasma, the targeted fatty acid profile in plasma and erythrocytes, several biomarkers of inflammation, and antioxidant defense using an innovative data integration analysis based on Latent Components. We observed that the fish oil-based lipid emulsion had an impact in several lipid subclasses, mainly glycerophosphocholines (PC), glycerophosphoserines (PS), glycerophosphoethanolamines (PE), oxidized PE (O-PE), 1-alkyl,2-acyl PS, lysophosphatidylethanolamines (LPE), oxidized PS (O-PS) and dicarboxylic acids. In contrast, the classic soybean oil emulsion did not. Several connections across the different blocks of data were found and aid in interpreting the impact of the lipid emulsions on metabolic health.

Sphingolipids as Regulators of Neuro-Inflammation and NADPH Oxidase 2

Neuro-inflammation accompanies numerous neurological disorders and conditions where it can be associated with a progressive neurodegenerative pathology. In a similar manner, alterations in sphingolipid metabolism often accompany or are causative features in degenerative neurological conditions. These include dementias, motor disorders, autoimmune conditions, inherited metabolic disorders, viral infection, traumatic brain and spinal cord injury, psychiatric conditions, and more. Sphingolipids are major regulators of cellular fate and function in addition to being important structural components of membranes. Their metabolism and signaling pathways can also be regulated by inflammatory mediators. Therefore, as certain sphingolipids exert distinct and opposing cellular roles, alterations in their metabolism can have major consequences. Recently, regulation of bioactive sphingolipids by neuro-inflammatory mediators has been shown to activate a neuronal NADPH oxidase 2 (NOX2) that can provoke damaging oxidation. Therefore, the sphingolipid-regulated neuronal NOX2 serves as a mechanistic link between neuro-inflammation and neurodegeneration. Moreover, therapeutics directed at sphingolipid metabolism or the sphingolipid-regulated NOX2 have the potential to alleviate neurodegeneration arising out of neuro-inflammation.

Targeting apoptotic caspases in cancer

Members of the caspase family of proteases play essential roles in the initiation and execution of apoptosis. These caspases are divided into two groups: the initiator caspases (caspase-2, -8, -9 and -10), which are the first to be activated in response to a signal, and the executioner caspases (caspase-3, -6, and -7) that carry out the demolition phase of apoptosis. Many conventional cancer therapies induce apoptosis to remove the cancer cell by engaging these caspases indirectly. Newer therapeutic applications have been designed, including those that specifically activate individual caspases using gene therapy approaches and small molecules that repress natural inhibitors of caspases already present in the cell. For such approaches to have maximal clinical efficacy, emerging insights into non-apoptotic roles of these caspases need to be considered. This review will discuss the roles of caspases as safeguards against cancer in the context of the advantages and potential limitations of targeting apoptotic caspases for the treatment of cancer.

The Neuroprotective Effect of miR-181a After Oxygen-Glucose Deprivation/Reperfusion and the Associated Mechanism

The level of miR-181a decreases rapidly in N2a cells following oxygen-glucose deprivation/reperfusion, but its role in this process is unclear. Reelin, a regulator of neuronal migration and synaptogenesis, is a predicted target of miR-181a. We hypothesized that miR-181a reduces neuronal apoptosis and protects neurons by targeting reelin. Second mitochondria-derived activator of caspases (Smac) is a protein located in mitochondria that regulates apoptosis. The pro-apoptotic effect of Smac is achieved by reversing the effects of apoptosis-inhibiting proteins (IAPs), particularly X-linked inhibitor of apoptosis (XIAP). We also evaluated the effect of miR-181a on the Smac/IAP signaling pathway after oxygen-glucose deprivation and reperfusion in N2a cells. The miR-181a level, apoptosis rate, and the levels of reelin mRNA and protein, Smac, and XIAP were assessed in N2a cells subjected to oxygen-glucose deprivation for 4 h and reperfusion for 0, 4, 12, or 24 h with/without an miR-181a mimic, or mismatched control. Direct targeting of reelin by miR-181a was assessed in vitro by dual luciferase assay and immunoblotting. Pre-treatment with miR-181a mimicked the increase in the miR-181a level in N2a cells after oxygen-glucose deprivation/reperfusion, resulting in a significant decrease in the apoptosis rate. Changes in the miR-181a level in N2a cells were inversely correlated with reelin protein expression. Direct targeting of the reelin 3' untranslated region by miR-181a was verified by dual luciferase assay, which showed that miR-181a significantly inhibited luciferase activity. The Smac level was significantly lower in the miR-181a mimics than the normal control and mimics-cont groups (P < 0.01), whereas the level of XIAP was increased slightly. These findings suggest that miR-181a protects neurons from apoptosis by inhibiting reelin expression and regulating the Smac/IAP signaling pathway after oxygen-glucose deprivation/reperfusion injury.

A novel caspase-6 from sea cucumber Holothuria leucospilota: Molecular characterization, expression analysis and apoptosis detection

In this study, a novel caspase-6 named HLcaspase-6 was identified from sea cucumber Holothuria leucospilota. The full-length cDNA of HLcaspase-6 is 2195 bp in size, containing a 126 bp 5'-untranslated region (UTR), a 1043 bp 3'-UTR and a 1026 bp open reading frame (ORF) encoding a protein of 341 amino acids with a deduced molecular weight of 38.57 kDa. HLcaspase-6 contains the common signatures of the caspase family, including the conserved pentapeptide motif QACRG, as well as the P20 and P10 domains. In addition, HLcaspase-6 contains a short pro-domain. HLcaspase-6 mRNA is ubiquitously expressed in all tissues examined, with the highest transcript level in the intestine, followed by coelomocytes. In in vitro experiments, the expression of HLcaspase-6 mRNA in coelomocytes was significantly up-regulated by lipopolysaccharides (LPS) or polyriboinosinic-polyribocytidylic acid [poly (I:C)] challenge, suggesting that HLcaspase-6 might play important roles in the innate immune defense of sea cucumber against bacterial and viral infections. Moreover, we further confirmed that overexpression of HLcaspase-6 could induce apoptosis and activate the p53 signal pathway.