The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Yusuf A Hannun - One of the best experts on this subject based on the ideXlab platform.
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ceramide and sphingosine 1 phosphate in cancer two faces of the sphinx
Translational cancer research, 2015Co-Authors: Mel Pilar Espaillat, Yusuf A Hannun, Mohamad Adada, Achraf A Shamseddine, Lina M ObeidAbstract:It is now well appreciated that bioactive Sphingolipids represent an important family of structural and signaling lipids. The focus on Sphingolipid research has grown exponentially since their bioactive properties were first described just over two decades ago. Today, Sphingolipid metabolites are established regulators of myriad cellular and pathological processes. Sphingolipid research is intricate due to the role of these molecules in vastly different biologies, their distinct structural properties and interconnected metabolic pathways. Ceramide and sphingosine-1-phosphate (S1P) have been defined as reciprocal regulators of cellular fate, and not surprisingly have been targeted for their role in cancer and their therapeutic potential. This review will describe the specific ways the Sphingolipid metabolic enzymes and lipids are metabolically interconnected and highlight recent findings to support the reciprocal role of ceramide and S1P in cellular processes and in cancer.
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on tissue localization of ceramides and other Sphingolipids by maldi mass spectrometry imaging
Analytical Chemistry, 2014Co-Authors: Ellen E. Jones, Yusuf A Hannun, Thierry Levade, Shaalee Dworski, Gemma Fabriàs, Daniel Canals, Josefina Casas, Drew Schoenling, Chadrick Denlinger, Jeffrey A. MedinAbstract:A novel MALDI-FTICR imaging mass spectrometry (MALDI-IMS) workflow is described for on-tissue detection, spatial localization, and structural confirmation of low abundance bioactive ceramides and other Sphingolipids. Increasingly, altered or elevated levels of Sphingolipids, Sphingolipid metabolites, and Sphingolipid metabolizing enzymes have been associated with a variety of disorders such as diabetes, obesity, lysosomal storage disorders, and cancer. Ceramide, which serves as a metabolic hub in Sphingolipid metabolism, has been linked to cancer signaling pathways and to metabolic regulation with involvement in autophagy, cell-cycle arrest, senescence, and apoptosis. Using kidney tissues from a new Farber disease mouse model in which ceramides of all acyl chain lengths and other Sphingolipid metabolites accumulate in tissues, specific ceramides and sphingomyelins were identified by on-tissue isolation and fragmentation, coupled with an on-tissue digestion by ceramidase or sphingomyelinase. Multiple glycoSphingolipid species were also detected. The newly generated library of Sphingolipid ions was then applied to MALDI-IMS of human lung cancer tissues. Multiple tumor specific ceramide and sphingomyelin species were detected and confirmed by on-tissue enzyme digests and structural confirmation. High-resolution MALDI-IMS in combination with novel on-tissue ceramidase and sphingomyelinase enzyme digestions makes it now possible to rapidly visualize the distribution of bioactive ceramides and sphingomyelin in tissues.
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Sphingolipid regulation of ezrin radixin and moesin proteins family implications for cell dynamics
Biochimica et Biophysica Acta, 2014Co-Authors: Mohamad Adada, Yusuf A Hannun, Daniel Canals, Lina M ObeidAbstract:A key but poorly studied domain of Sphingolipid functions encompasses endocytosis, exocytosis, cellular trafficking, and cell movement. Recently, the ezrin, radixin and moesin (ERM) family of proteins emerged as novel potent targets regulated by Sphingolipids. ERMs are structural proteins linking the actin cytoskeleton to the plasma membrane, also forming a scaffold for signaling pathways that are used for cell proliferation, migration and invasion, and cell division. Opposing functions of the bioactive Sphingolipid ceramide and sphingosine-1-phosphate (S1P), contribute to ERM regulation. S1P robustly activates whereas ceramide potently deactivates ERM via phosphorylation/dephosphorylation, respectively. This recent dimension of cytoskeletal regulation by Sphingolipids opens up new avenues to target cell dynamics, and provides further understanding of some of the unexplained biological effects mediated by Sphingolipids. In addition, these studies are providing novel inroads into defining basic mechanisms of regulation and action of bioactive Sphingolipids. This review describes the current understanding of Sphingolipid regulation of the cytoskeleton, it also describes the biologies in which ERM proteins have been involved, and finally how these two large fields have started to converge. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.
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sphingoid bases and the serine catabolic enzyme cha1 define a novel feedforward feedback mechanism in the response to serine availability
Journal of Biological Chemistry, 2012Co-Authors: David J Montefusco, Benjamin Newcomb, Jason L Gandy, Sarah E Brice, Ashley L Cowart, Nabil Matmati, Yusuf A HannunAbstract:Targets of bioactive Sphingolipids in Saccharomyces cerevisiae were previously identified using microarray experiments focused on Sphingolipid-dependent responses to heat stress. One of these heat-induced genes is the serine deamidase/dehydratase Cha1 known to be regulated by increased serine availability. This study investigated the hypothesis that Sphingolipids may mediate the induction of Cha1 in response to serine availability. The results showed that inhibition of de novo synthesis of Sphingolipids, pharmacologically or genetically, prevented the induction of Cha1 in response to increased serine availability. Additional studies implicated the sphingoid bases phytosphingosine and dihydrosphingosine as the likely mediators of Cha1 up-regulation. The yeast protein kinases Pkh1 and Pkh2, known sphingoid base effectors, were found to mediate CHA1 up-regulation via the transcription factor Cha4. Because the results disclosed a role for Sphingolipids in negative feedback regulation of serine metabolism, we investigated the effects of disrupting this mechanism on Sphingolipid levels and on cell growth. Intriguingly, exposure of the cha1Δ strain to high serine resulted in hyperaccumulation of endogenous serine and in turn a significant accumulation of sphingoid bases and ceramides. Under these conditions, the cha1Δ strain displayed a significant growth defect that was Sphingolipid-dependent. Together, this work reveals a feedforward/feedback loop whereby the sphingoid bases serve as sensors of serine availability and mediate up-regulation of Cha1 in response to serine availability, which in turn regulates Sphingolipid levels by limiting serine accumulation.
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Drug targeting of Sphingolipid metabolism: sphingomyelinases and ceramidases.
British journal of pharmacology, 2011Co-Authors: Daniel Canals, David M. Perry, Russell W. Jenkins, Yusuf A HannunAbstract:Sphingolipids represent a class of diverse bioactive lipid molecules that are increasingly appreciated as key modulators of diverse physiologic and pathophysiologic processes that include cell growth, cell death, autophagy, angiogenesis, and stress and inflammatory responses. Sphingomyelinases and ceramidases are key enzymes of Sphingolipid metabolism that regulate the formation and degradation of ceramide, one of the most intensely studied classes of Sphingolipids. Improved understanding of these enzymes that control not only the levels of ceramide but also the complex interconversion of Sphingolipid metabolites has provided the foundation for the functional analysis of the roles of Sphingolipids. Our current understanding of the roles of various Sphingolipids in the regulation of different cellular processes has come from loss-of-function/gain-of-function studies utilizing genetic deletion/downregulation/overexpression of enzymes of Sphingolipid metabolism (e.g. knockout animals, RNA interference) and from the use of pharmacologic inhibitors of these same enzymes. While genetic approaches to evaluate the functional roles of Sphingolipid enzymes have been instrumental in advancing the field, the use of pharmacologic inhibitors has been equally important in identifying new roles for Sphingolipids in important cellular processes.The latter also promises the development of novel therapeutic targets with implications for cancer therapy, inflammation, diabetes, and neurodegeneration. In this review, we focus on the status and use of pharmacologic compounds that inhibit sphingomyelinases and ceramidases, and we will review the history, current uses and future directions for various small molecule inhibitors, and will highlight studies in which inhibitors of Sphingolipid metabolizing enzymes have been used to effectively treat models of human disease.
John R. Jefferson - One of the best experts on this subject based on the ideXlab platform.
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effect of sterol carrier protein 2 expression on Sphingolipid distribution in plasma membrane lipid rafts caveolae
Lipids, 2007Co-Authors: Barbara P. Atshaves, John R. Jefferson, Avery L. Mcintosh, Bonnie M. Mccann, Kerstin K. Landrock, Ann B. Kier, Adalberto M Gallegos, Friedhelm SchroederAbstract:Although Sphingolipids are highly important signaling molecules enriched in lipid rafts/caveolae, relatively little is known regarding factors such as Sphingolipid binding proteins that may regulate the distribution of Sphingolipids to lipid rafts/caveolae of living cells. Since early work demonstrated that sterol carrier protein-2 (SCP-2) enhanced glycoSphingolipid transfer from membranes in vitro, the effect of SCP-2 expression on Sphingolipid distribution to lipid rafts/caveolae in living cells was examined. Using a non-detergent affinity chromatography method to isolate lipid rafts/caveolae and non-rafts from purified L-cell plasma membranes, it was shown that lipid rafts/caveolae were highly enriched in multiple Sphingolipid species including ceramides, acidic glycoSphingolipids (ganglioside GM1); neutral glycoSphingolipids (monohexosides, dihexosides, globosides), and sphingomyelin as compared to non-raft domains. SCP-2 overexpression further enriched the content of total Sphingolipids and select Sphingolipid species in the lipid rafts/caveolae domains. Analysis of fluorescence binding and displacement data revealed that purified human recombinant SCP-2 exhibited high binding affinity (nanomolar range) for all Sphingolipid classes tested. The binding affinity decreased in the following order: ceramides > acidic glycoSphingolipid (ganglioside GM1) > neutral glycoSphingolipid (monohexosides, hexosides, globosides) > sphingomyelin. Enrichment of individual Sphingolipid classes to lipid rafts/caveolae versus non-rafts in SCP-2 expressing plasma membranes followed closely with those classes most strongly bound to SCP-2 (ceramides, GM1 > the neutral glycoSphingolipids (monohexosides, dihexosides, and globosides) > sphingomyelin). Taken together these data suggested that SCP-2 acts to selectively regulate Sphingolipid distribution to lipid rafts/caveolae in living cells.
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sterol carrier protein 2 expression alters Sphingolipid metabolism in transfected mouse l cell fibroblasts
Molecular and Cellular Biochemistry, 2006Co-Authors: Daniel G Milis, Friedhelm Schroeder, Barbara P. Atshaves, Messiah K Moore, John R. JeffersonAbstract:The influence of sterol carrier protein-2 (SCP-2) on the cellular metabolism of Sphingolipids was examined in control mouse L-cells and stably transfected clones expressing the protein SCP-2. Three approaches were used to examine for differences; (1) compositional analysis of endogenous Sphingolipid classes, (2) metabolism of NBD-ceramide, and (3) live cell labelling via endocytic uptake of BODIPY-sphingomyelin. SCP-2 over expression significantly altered the endogenous levels of both neutral and acidic Sphingolipid classes. Among the neutral Sphingolipids, expression of SCP-2 induced a 1.7-fold increase in the level of lactosylceramide (LacCer, p < 0.05) and a similar fold decrease in the level of the higher-order neutral glycosylceramides (p < 0.05). Among the acidic Sphingolipids, SCP-2 resulted in a 5.2-fold decrease in the endogenous plasma membrane level of ganglioside GM1 (p < 0.03). Incubation of both control and transfected cell lines with NBD-ceramide resulted in the rapid establishment of a steady-state distribution of NBD-labelled sphingomyelin (NBD-SM) and glucosylceramide (NBD-GlcCer). In the SCP-2 expressing clones the conversion of NBD-Cer to NBD-GlcCer was 30% lower during incubation periods between 5 and 30 min (p < 0.025). Inspection of the cells by fluorescence microscopy after incubation with BODIPY labelled sphingomyelin (BODIPY-SM) revealed similar punctuated patterns with no distinguishable differences between the cell types. These results imply that SCP-2 plays a role in modulating enzymatic steps involved in metabolism of Sphingolipid homeostasis.
Daniel Canals - One of the best experts on this subject based on the ideXlab platform.
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On-Tissue Localization of Ceramides and Other Sphingolipids by MALDI Mass Spectrometry Imaging
2015Co-Authors: Ellen E. Jones, Thierry Levade, Shaalee Dworski, Gemma Fabriàs, Daniel Canals, Josefina Casas, Drew Schoenling, Chadrick Denlinger, Yusuf A. Hannun, Jeffrey A. MedinAbstract:A novel MALDI-FTICR imaging mass spectrometry (MALDI-IMS) workflow is described for on-tissue detection, spatial localization, and structural confirmation of low abundance bioactive ceramides and other Sphingolipids. Increasingly, altered or elevated levels of Sphingolipids, Sphingolipid metabolites, and Sphingolipid metabolizing enzymes have been associated with a variety of disorders such as diabetes, obesity, lysosomal storage disorders, and cancer. Ceramide, which serves as a metabolic hub in Sphingolipid metabolism, has been linked to cancer signaling pathways and to metabolic regulation with involvement in autophagy, cell-cycle arrest, senescence, and apoptosis. Using kidney tissues from a new Farber disease mouse model in which ceramides of all acyl chain lengths and other Sphingolipid metabolites accumulate in tissues, specific ceramides and sphingomyelins were identified by on-tissue isolation and fragmentation, coupled with an on-tissue digestion by ceramidase or sphingomyelinase. Multiple glycoSphingolipid species were also detected. The newly generated library of Sphingolipid ions was then applied to MALDI-IMS of human lung cancer tissues. Multiple tumor specific ceramide and sphingomyelin species were detected and confirmed by on-tissue enzyme digests and structural confirmation. High-resolution MALDI-IMS in combination with novel on-tissue ceramidase and sphingomyelinase enzyme digestions makes it now possible to rapidly visualize the distribution of bioactive ceramides and sphingomyelin in tissues
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on tissue localization of ceramides and other Sphingolipids by maldi mass spectrometry imaging
Analytical Chemistry, 2014Co-Authors: Ellen E. Jones, Yusuf A Hannun, Thierry Levade, Shaalee Dworski, Gemma Fabriàs, Daniel Canals, Josefina Casas, Drew Schoenling, Chadrick Denlinger, Jeffrey A. MedinAbstract:A novel MALDI-FTICR imaging mass spectrometry (MALDI-IMS) workflow is described for on-tissue detection, spatial localization, and structural confirmation of low abundance bioactive ceramides and other Sphingolipids. Increasingly, altered or elevated levels of Sphingolipids, Sphingolipid metabolites, and Sphingolipid metabolizing enzymes have been associated with a variety of disorders such as diabetes, obesity, lysosomal storage disorders, and cancer. Ceramide, which serves as a metabolic hub in Sphingolipid metabolism, has been linked to cancer signaling pathways and to metabolic regulation with involvement in autophagy, cell-cycle arrest, senescence, and apoptosis. Using kidney tissues from a new Farber disease mouse model in which ceramides of all acyl chain lengths and other Sphingolipid metabolites accumulate in tissues, specific ceramides and sphingomyelins were identified by on-tissue isolation and fragmentation, coupled with an on-tissue digestion by ceramidase or sphingomyelinase. Multiple glycoSphingolipid species were also detected. The newly generated library of Sphingolipid ions was then applied to MALDI-IMS of human lung cancer tissues. Multiple tumor specific ceramide and sphingomyelin species were detected and confirmed by on-tissue enzyme digests and structural confirmation. High-resolution MALDI-IMS in combination with novel on-tissue ceramidase and sphingomyelinase enzyme digestions makes it now possible to rapidly visualize the distribution of bioactive ceramides and sphingomyelin in tissues.
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Sphingolipid regulation of ezrin radixin and moesin proteins family implications for cell dynamics
Biochimica et Biophysica Acta, 2014Co-Authors: Mohamad Adada, Yusuf A Hannun, Daniel Canals, Lina M ObeidAbstract:A key but poorly studied domain of Sphingolipid functions encompasses endocytosis, exocytosis, cellular trafficking, and cell movement. Recently, the ezrin, radixin and moesin (ERM) family of proteins emerged as novel potent targets regulated by Sphingolipids. ERMs are structural proteins linking the actin cytoskeleton to the plasma membrane, also forming a scaffold for signaling pathways that are used for cell proliferation, migration and invasion, and cell division. Opposing functions of the bioactive Sphingolipid ceramide and sphingosine-1-phosphate (S1P), contribute to ERM regulation. S1P robustly activates whereas ceramide potently deactivates ERM via phosphorylation/dephosphorylation, respectively. This recent dimension of cytoskeletal regulation by Sphingolipids opens up new avenues to target cell dynamics, and provides further understanding of some of the unexplained biological effects mediated by Sphingolipids. In addition, these studies are providing novel inroads into defining basic mechanisms of regulation and action of bioactive Sphingolipids. This review describes the current understanding of Sphingolipid regulation of the cytoskeleton, it also describes the biologies in which ERM proteins have been involved, and finally how these two large fields have started to converge. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.
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Drug targeting of Sphingolipid metabolism: sphingomyelinases and ceramidases.
British journal of pharmacology, 2011Co-Authors: Daniel Canals, David M. Perry, Russell W. Jenkins, Yusuf A HannunAbstract:Sphingolipids represent a class of diverse bioactive lipid molecules that are increasingly appreciated as key modulators of diverse physiologic and pathophysiologic processes that include cell growth, cell death, autophagy, angiogenesis, and stress and inflammatory responses. Sphingomyelinases and ceramidases are key enzymes of Sphingolipid metabolism that regulate the formation and degradation of ceramide, one of the most intensely studied classes of Sphingolipids. Improved understanding of these enzymes that control not only the levels of ceramide but also the complex interconversion of Sphingolipid metabolites has provided the foundation for the functional analysis of the roles of Sphingolipids. Our current understanding of the roles of various Sphingolipids in the regulation of different cellular processes has come from loss-of-function/gain-of-function studies utilizing genetic deletion/downregulation/overexpression of enzymes of Sphingolipid metabolism (e.g. knockout animals, RNA interference) and from the use of pharmacologic inhibitors of these same enzymes. While genetic approaches to evaluate the functional roles of Sphingolipid enzymes have been instrumental in advancing the field, the use of pharmacologic inhibitors has been equally important in identifying new roles for Sphingolipids in important cellular processes.The latter also promises the development of novel therapeutic targets with implications for cancer therapy, inflammation, diabetes, and neurodegeneration. In this review, we focus on the status and use of pharmacologic compounds that inhibit sphingomyelinases and ceramidases, and we will review the history, current uses and future directions for various small molecule inhibitors, and will highlight studies in which inhibitors of Sphingolipid metabolizing enzymes have been used to effectively treat models of human disease.
Lina M Obeid - One of the best experts on this subject based on the ideXlab platform.
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ceramide and sphingosine 1 phosphate in cancer two faces of the sphinx
Translational cancer research, 2015Co-Authors: Mel Pilar Espaillat, Yusuf A Hannun, Mohamad Adada, Achraf A Shamseddine, Lina M ObeidAbstract:It is now well appreciated that bioactive Sphingolipids represent an important family of structural and signaling lipids. The focus on Sphingolipid research has grown exponentially since their bioactive properties were first described just over two decades ago. Today, Sphingolipid metabolites are established regulators of myriad cellular and pathological processes. Sphingolipid research is intricate due to the role of these molecules in vastly different biologies, their distinct structural properties and interconnected metabolic pathways. Ceramide and sphingosine-1-phosphate (S1P) have been defined as reciprocal regulators of cellular fate, and not surprisingly have been targeted for their role in cancer and their therapeutic potential. This review will describe the specific ways the Sphingolipid metabolic enzymes and lipids are metabolically interconnected and highlight recent findings to support the reciprocal role of ceramide and S1P in cellular processes and in cancer.
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Sphingolipid regulation of ezrin radixin and moesin proteins family implications for cell dynamics
Biochimica et Biophysica Acta, 2014Co-Authors: Mohamad Adada, Yusuf A Hannun, Daniel Canals, Lina M ObeidAbstract:A key but poorly studied domain of Sphingolipid functions encompasses endocytosis, exocytosis, cellular trafficking, and cell movement. Recently, the ezrin, radixin and moesin (ERM) family of proteins emerged as novel potent targets regulated by Sphingolipids. ERMs are structural proteins linking the actin cytoskeleton to the plasma membrane, also forming a scaffold for signaling pathways that are used for cell proliferation, migration and invasion, and cell division. Opposing functions of the bioactive Sphingolipid ceramide and sphingosine-1-phosphate (S1P), contribute to ERM regulation. S1P robustly activates whereas ceramide potently deactivates ERM via phosphorylation/dephosphorylation, respectively. This recent dimension of cytoskeletal regulation by Sphingolipids opens up new avenues to target cell dynamics, and provides further understanding of some of the unexplained biological effects mediated by Sphingolipids. In addition, these studies are providing novel inroads into defining basic mechanisms of regulation and action of bioactive Sphingolipids. This review describes the current understanding of Sphingolipid regulation of the cytoskeleton, it also describes the biologies in which ERM proteins have been involved, and finally how these two large fields have started to converge. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.
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a deficiency of ceramide biosynthesis causes cerebellar purkinje cell neurodegeneration and lipofuscin accumulation
PLOS Genetics, 2011Co-Authors: Lihong Zhao, Yusuf A Hannun, Lina M Obeid, Stefka D Spassieva, Thomas J Jucius, Leonard D Shultz, Elizabeth H Shick, Wendy B Macklin, Susan L AckermanAbstract:Sphingolipids, lipids with a common sphingoid base (also termed long chain base) backbone, play essential cellular structural and signaling functions. Alterations of Sphingolipid levels have been implicated in many diseases, including neurodegenerative disorders. However, it remains largely unclear whether Sphingolipid changes in these diseases are pathological events or homeostatic responses. Furthermore, how changes in Sphingolipid homeostasis shape the progression of aging and neurodegeneration remains to be clarified. We identified two mouse strains, flincher (fln) and toppler (to), with spontaneous recessive mutations that cause cerebellar ataxia and Purkinje cell degeneration. Positional cloning demonstrated that these mutations reside in the Lass1 gene. Lass1 encodes (dihydro)ceramide synthase 1 (CerS1), which is highly expressed in neurons. Both fln and to mutations caused complete loss of CerS1 catalytic activity, which resulted in a reduction in Sphingolipid biosynthesis in the brain and dramatic changes in steady-state levels of Sphingolipids and sphingoid bases. In addition to Purkinje cell death, deficiency of CerS1 function also induced accumulation of lipofuscin with ubiquitylated proteins in many brain regions. Our results demonstrate clearly that ceramide biosynthesis deficiency can cause neurodegeneration and suggest a novel mechanism of lipofuscin formation, a common phenomenon that occurs during normal aging and in some neurodegenerative diseases.
Jeffrey A. Medin - One of the best experts on this subject based on the ideXlab platform.
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On-Tissue Localization of Ceramides and Other Sphingolipids by MALDI Mass Spectrometry Imaging
2015Co-Authors: Ellen E. Jones, Thierry Levade, Shaalee Dworski, Gemma Fabriàs, Daniel Canals, Josefina Casas, Drew Schoenling, Chadrick Denlinger, Yusuf A. Hannun, Jeffrey A. MedinAbstract:A novel MALDI-FTICR imaging mass spectrometry (MALDI-IMS) workflow is described for on-tissue detection, spatial localization, and structural confirmation of low abundance bioactive ceramides and other Sphingolipids. Increasingly, altered or elevated levels of Sphingolipids, Sphingolipid metabolites, and Sphingolipid metabolizing enzymes have been associated with a variety of disorders such as diabetes, obesity, lysosomal storage disorders, and cancer. Ceramide, which serves as a metabolic hub in Sphingolipid metabolism, has been linked to cancer signaling pathways and to metabolic regulation with involvement in autophagy, cell-cycle arrest, senescence, and apoptosis. Using kidney tissues from a new Farber disease mouse model in which ceramides of all acyl chain lengths and other Sphingolipid metabolites accumulate in tissues, specific ceramides and sphingomyelins were identified by on-tissue isolation and fragmentation, coupled with an on-tissue digestion by ceramidase or sphingomyelinase. Multiple glycoSphingolipid species were also detected. The newly generated library of Sphingolipid ions was then applied to MALDI-IMS of human lung cancer tissues. Multiple tumor specific ceramide and sphingomyelin species were detected and confirmed by on-tissue enzyme digests and structural confirmation. High-resolution MALDI-IMS in combination with novel on-tissue ceramidase and sphingomyelinase enzyme digestions makes it now possible to rapidly visualize the distribution of bioactive ceramides and sphingomyelin in tissues
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on tissue localization of ceramides and other Sphingolipids by maldi mass spectrometry imaging
Analytical Chemistry, 2014Co-Authors: Ellen E. Jones, Yusuf A Hannun, Thierry Levade, Shaalee Dworski, Gemma Fabriàs, Daniel Canals, Josefina Casas, Drew Schoenling, Chadrick Denlinger, Jeffrey A. MedinAbstract:A novel MALDI-FTICR imaging mass spectrometry (MALDI-IMS) workflow is described for on-tissue detection, spatial localization, and structural confirmation of low abundance bioactive ceramides and other Sphingolipids. Increasingly, altered or elevated levels of Sphingolipids, Sphingolipid metabolites, and Sphingolipid metabolizing enzymes have been associated with a variety of disorders such as diabetes, obesity, lysosomal storage disorders, and cancer. Ceramide, which serves as a metabolic hub in Sphingolipid metabolism, has been linked to cancer signaling pathways and to metabolic regulation with involvement in autophagy, cell-cycle arrest, senescence, and apoptosis. Using kidney tissues from a new Farber disease mouse model in which ceramides of all acyl chain lengths and other Sphingolipid metabolites accumulate in tissues, specific ceramides and sphingomyelins were identified by on-tissue isolation and fragmentation, coupled with an on-tissue digestion by ceramidase or sphingomyelinase. Multiple glycoSphingolipid species were also detected. The newly generated library of Sphingolipid ions was then applied to MALDI-IMS of human lung cancer tissues. Multiple tumor specific ceramide and sphingomyelin species were detected and confirmed by on-tissue enzyme digests and structural confirmation. High-resolution MALDI-IMS in combination with novel on-tissue ceramidase and sphingomyelinase enzyme digestions makes it now possible to rapidly visualize the distribution of bioactive ceramides and sphingomyelin in tissues.
