Bax distribution into mitochondrial detergent‐resistant microdomains is related to ceramide and cholesterol content in postischemic hearts

Martínez-Abundis, Eduardo; Correa, Francisco; Pavón, Natalia; Zazueta, Cecilia

doi:10.1111/j.1742-4658.2009.07239.x

Cited by 47 publications

(35 citation statements)

References 41 publications

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“…Moreover, accumulation of endogenous ceramide by targeting bacterial SMase to mitochondria caused Bax translocation to mitochondria, cytochrome c release, and cell death (40,41). More recently, studies have reported that Bax preferentially associates with mitochondrial membrane microenvironments enriched in ceramide (26) and have also indicated that ceramide increases the membrane permeability of isolated mitochondria for cytochrome c release (42). Moreover, ceramide can form channels in mitochondrial outer membranes within the concentration range that is present in mitochondria during the induction phase of apoptosis (43), and additional studies showed that both recombinant human Bcl-x(L) and a C. elegans Bcl-2 homologue can disassemble ceramide channels in the mitochondrial outer membranes of isolated mitochondria from rat liver and yeast.…”

Section: Discussionmentioning

confidence: 99%

“…Ceramide has also been implicated in mitochondria-mediated apoptosis (22)(23)(24). However, the direct regulation of sphingolipids in mitochondria or mitochondria-associated membranes is mostly unclear with few reports detecting changes in mitochondrial ceramide in response to induction of apoptosis (25,26). This lack of information on SMase and other sphingolipid-regulating enzymes in mitochondria has significantly handicapped efforts to delineate signaling pathways in this organelle that involve sphingolipids.…”

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confidence: 99%

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Identification and Characterization of Murine Mitochondria-associated Neutral Sphingomyelinase (MA-nSMase), the Mammalian Sphingomyelin Phosphodiesterase 5

Rajagopalan

Roddy

et al. 2010

Journal of Biological Chemistry

114

115

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Sphingolipids play important roles in regulating cellular responses. Although mitochondria contain sphingolipids, direct regulation of their levels in mitochondria or mitochondria-associated membranes is mostly unclear. Neutral SMase (N-SMase) isoforms, which catalyze hydrolysis of sphingomyelin (SM) to ceramide and phosphocholine, have been found in the mitochondria of yeast and zebrafish, yet their existence in mammalian mitochondria remains unknown. Here, we have identified and cloned a cDNA based on nSMase homologous sequences. This cDNA encodes a novel protein of 483 amino acids that displays significant homology to nSMase2 and possesses the same catalytic core residues as members of the extended N-SMase family. A transiently expressed V5-tagged protein co-localized with both mitochondria and endoplasmic reticulum markers in MCF-7 and HEK293 cells; accordingly, the enzyme is referred to as mitochondria-associated nSMase (MAnSMase). MA-nSMase was highly expressed in testis, pancreas, epididymis, and brain. MA-nSMase had an absolute requirement for cations such as Mg 2؉ and Mn 2؉ and activation by the anionic phospholipids, especially phosphatidylserine and the mitochondrial cardiolipin. Importantly, overexpression of MA-nSMase in HEK293 cells significantly increased in vitro N-SMase activity and also modulated the levels of SM and ceramide, indicating that the identified cDNA encodes a functional SMase. Thus, these studies identify and characterize, for the first time, a mammalian MA-nSMase. The characterization of MA-nSMase described here will contribute to our understanding of pathways regulated by sphingolipid metabolites, particularly with reference to the mitochondria and associated organelles.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Identification and Characterization of Murine Mitochondria-associated Neutral Sphingomyelinase (MA-nSMase), the Mammalian Sphingomyelin Phosphodiesterase 5

Rajagopalan

Roddy

et al. 2010

Journal of Biological Chemistry

114

115

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“…Furthermore, ceramide and activated Bax directly interact in vitro to synergistically induce outer membrane permeabilization in isolated mitochondria ( 61 ). Moreover, Bax association with ceramideenriched detergent-resistant membrane domains occurs in situ upon ischemia/reperfusion, a well-characterized apoptotic model ( 62 ). Further investigation has characterized the assembly of mitochondrial ceramide-rich macrodomains (MCRM) with enhanced association of Bax oligomers upon exposure to radiation ( 63 ).…”

Section: Ceramidementioning

confidence: 99%

Sphingolipids: regulators of crosstalk between apoptosis and autophagy

Young

Kester

Wang

2013

Journal of Lipid Research

294

274

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decades ago, pioneering work by Hannun et al. and Kolesnick et al. established the foundation for the bioactive nature of sphingolipids by demonstrating the inhibition of protein kinase C (PKC) by sphingosine and the stimulation of a ceramide-activated protein kinase in response to tumor necrosis factor (TNF)-␣ , respectively ( 1, 2 ). Sphingolipids have since been recognized as critical activators or inhibitors of various protein kinases and phosphatases, receptors, and ion transporters ( 3 ). Moreover, sphingolipids have been identifi ed as key regulators of a vast number of cellular processes, including cell growth, adhesion, migration, senescence, apoptosis, and most recently, autophagy ( 3, 4 ).Much of the investigation into sphingolipid signaling has focused on the disparate nature of ceramide and sphingosine-1-phosphate (S1P). Ceramide is typically associated with growth arrest and apoptosis, while S1P promotes cell proliferation and survival. The opposing nature and dynamic balance of intracellular ceramide and S1P, termed the "sphingolipid rheostat," has been proposed to determine cell fate ( 5 ). However, emerging evidence and extensive characterization of the sphingolipid metabolic network suggests that this two-dimensional model does not adequately refl ect sphingolipid signaling and function within the cell. In addition to ceramide and S1P, other sphingolipid metabolites, such as sphingosine, dihydroceramide, and gangliosides, have been implicated in the regulation of apoptosis and macroautophagy (hereafter referred to as autophagy). Although autophagy is typically considered to be a cytoprotective mechanism for the suppression of apoptosis, recent evidence indicates that autophagy can also promote cell death ( 6 ). Due to the differential regulation of apoptosis and autophagy by sphingolipid metabolites, the sphingolipid network has emerged as a novel molecular switch between the apoptotic and autophagic Abstract Apoptosis and autophagy are two evolutionarily conserved processes that maintain homeostasis during stress. Although the two pathways utilize fundamentally distinct machinery, apoptosis and autophagy are highly interconnected and share many key regulators. The crosstalk between apoptosis and autophagy is complex, as autophagy can function to promote cell survival or cell death under various cellular conditions. The molecular mechanisms of crosstalk are beginning to be elucidated and have critical implications for the treatment of various diseases, such as cancer. Sphingolipids are a class of bioactive lipids that mediate many key cellular processes, including apoptosis and autophagy. By targeting several of the shared regulators, sphingolipid metabolites differentially regulate the induction of apoptosis and autophagy. Importantly, individual sphingolipid species appear to "switch" autophagy toward cell survival (e.g., sphingosine-1-phosphate) or cell death (e.g., ceramide, gangliosides). This review assesses the current understanding of sphingolipid-induced apoptosis and autophagy to addr...

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“…The homogenates were cleared at 1,500 Â g, and the mitochondria were spun down at 10,000 Â g. Cholesterol depletion in the mitochondrial membranes was achieved by treatment with Me-b-cyclodextrin (b-MCD) (SigmaAldrich) as previously described. 72 Cholesterol enrichment was achieved by incubating isolated mitochondria with a cholesterol-BSA complex as described in Martínez et al 73 For cytochrome c release assays, 30 mg of crude mitochondria was resuspended at 1 mg/mL in KCl buffer supplemented with succinate (5 mM) and EGTA (0.5 mM). Peptides were added to the samples at various concentrations, and incubations were carried out at 30 C under agitation (300 rpm).…”

Section: Mitochondrial Assaysmentioning

confidence: 99%

Systemic Delivery of Tumor-Targeted Bax-Derived Membrane-Active Peptides for the Treatment of Melanoma Tumors in a Humanized SCID Mouse Model

et al. 2017

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Melanoma is a highly metastatic and deadly form of cancer. Invasive melanoma cells overexpress integrin a v b 3 , which is a well-known target for Arg-Gly-Asp-based (RGD) peptides. We developed a sophisticated method to synthetize milligram amounts of a targeted vector that allows the RGD-mediated targeting, internalization, and release of a mitochondria-disruptive peptide derived from the pro-apoptotic Bax protein. We found that 2.5 mM Bax[109-127] was sufficient to destabilize the mitochondria in ten different tumor cell lines, even in the presence of the anti-apoptotic Bcl2 protein, which is often involved in tumor resistance. This pore-forming peptide displayed antitumor activity when it was covalently linked by a disulfide bridge to the tetrameric RAFT-c[RGD] 4 -platform and after intravenous injection in a human melanoma tumor model established in humanized immuno-competent mice. In addition to its direct toxic effect, treatment with this combination induced the release of the immuno-stimulating factor monocyte chimoattractant protein 1 (MCP1) in the blood and a decrease in the level of the pro-angiogenic factor FGF2. Our novel multifunctional, apoptosis-inducing agent could be further customized and assayed for potential use in tumortargeted therapy.

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Bax distribution into mitochondrial detergent‐resistant microdomains is related to ceramide and cholesterol content in postischemic hearts

Cited by 47 publications

References 41 publications

Identification and Characterization of Murine Mitochondria-associated Neutral Sphingomyelinase (MA-nSMase), the Mammalian Sphingomyelin Phosphodiesterase 5

Identification and Characterization of Murine Mitochondria-associated Neutral Sphingomyelinase (MA-nSMase), the Mammalian Sphingomyelin Phosphodiesterase 5

Sphingolipids: regulators of crosstalk between apoptosis and autophagy

Systemic Delivery of Tumor-Targeted Bax-Derived Membrane-Active Peptides for the Treatment of Melanoma Tumors in a Humanized SCID Mouse Model

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