The compartmentalization and translocation of the sphingosine kinases: Mechanisms and functions in cell signaling and sphingolipid metabolism

Photoactivation ('uncaging’) is a powerful approach for releasing bioactive small-molecules in living cells. Current uncaging methods are limited by the random distribution of caged molecules within cells. We have developed a mitochondria-specific photoactivation method, which permitted us to release free sphingosine inside mitochondria and thereafter monitor local sphingosine metabolism by lipidomics. Our results indicate that sphingosine was quickly phosphorylated into sphingosine 1-phosphate (S1P) driven by sphingosine kinases. In time-course studies, the mitochondria-specific uncaged sphingosine demonstrated distinct metabolic patterns compared to globally-released sphingosine, and did not induce calcium spikes. Our data provide direct evidence that sphingolipid metabolism and signaling are highly dependent on the subcellular location and opens up new possibilities to study the effects of lipid localization on signaling and metabolic fate.

Download Full-text

Novelty of Sphingolipids in the Central Nervous System Physiology and Disease: Focusing on the Sphingolipid Hypothesis of Neuroinflammation and Neurodegeneration

International Journal of Molecular Sciences ◽

10.3390/ijms22147353 ◽

2021 ◽

Vol 22 (14) ◽

pp. 7353

Author(s):

Maria Ayub ◽

Hee-Kyung Jin ◽

Jae-sung Bae

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Neurodegenerative Disorders ◽

Sphingolipid Metabolism ◽

Bioactive Lipids ◽

Metabolic Intermediates ◽

Sphingosine 1 Phosphate ◽

Sphingosine Kinases ◽

The Central Nervous System ◽

System Physiology

For decades, lipids were confined to the field of structural biology and energetics as they were considered only structural constituents of cellular membranes and efficient sources of energy production. However, with advances in our understanding in lipidomics and improvements in the technological approaches, astounding discoveries have been made in exploring the role of lipids as signaling molecules, termed bioactive lipids. Among these bioactive lipids, sphingolipids have emerged as distinctive mediators of various cellular processes, ranging from cell growth and proliferation to cellular apoptosis, executing immune responses to regulating inflammation. Recent studies have made it clear that sphingolipids, their metabolic intermediates (ceramide, sphingosine-1-phosphate, and N-acetyl sphingosine), and enzyme systems (cyclooxygenases, sphingosine kinases, and sphingomyelinase) harbor diverse yet interconnected signaling pathways in the central nervous system (CNS), orchestrate CNS physiological processes, and participate in a plethora of neuroinflammatory and neurodegenerative disorders. Considering the unequivocal importance of sphingolipids in CNS, we review the recent discoveries detailing the major enzymes involved in sphingolipid metabolism (particularly sphingosine kinase 1), novel metabolic intermediates (N-acetyl sphingosine), and their complex interactions in CNS physiology, disruption of their functionality in neurodegenerative disorders, and therapeutic strategies targeting sphingolipids for improved drug approaches.

Download Full-text

The sphingosine 1-phosphate receptor 2/4 antagonist JTE-013 elicits off-target effects on sphingolipid metabolism

Scientific Reports ◽

10.1038/s41598-021-04009-w ◽

2022 ◽

Vol 12 (1) ◽

Author(s):

Melissa R. Pitman ◽

Alexander C. Lewis ◽

Lorena T. Davies ◽

Paul A. B. Moretti ◽

Dovile Anderson ◽

...

Keyword(s):

Sphingolipid Metabolism ◽

Protein Targets ◽

S1p Receptors ◽

Sphingosine 1 Phosphate ◽

Sphingosine Kinases ◽

Dihydroceramide Desaturase ◽

Dihydroceramide Desaturase 1 ◽

G Protein Coupled ◽

Potential Therapeutics ◽

Target Effects

AbstractSphingosine 1-phosphate (S1P) is a signaling lipid that has broad roles, working either intracellularly through various protein targets, or extracellularly via a family of five G-protein coupled receptors. Agents that selectively and specifically target each of the S1P receptors have been sought as both biological tools and potential therapeutics. JTE-013, a small molecule antagonist of S1P receptors 2 and 4 (S1P2 and S1P4) has been widely used in defining the roles of these receptors in various biological processes. Indeed, our previous studies showed that JTE-013 had anti-acute myeloid leukaemia (AML) activity, supporting a role for S1P2 in the biology and therapeutic targeting of AML. Here we examined this further and describe lipidomic analysis of AML cells that revealed JTE-013 caused alterations in sphingolipid metabolism, increasing cellular ceramides, dihydroceramides, sphingosine and dihydrosphingosine. Further examination of the mechanisms behind these observations showed that JTE-013, at concentrations frequently used in the literature to target S1P2/4, inhibits several sphingolipid metabolic enzymes, including dihydroceramide desaturase 1 and both sphingosine kinases. Collectively, these findings demonstrate that JTE-013 can have broad off-target effects on sphingolipid metabolism and highlight that caution must be employed in interpreting the use of this reagent in defining the roles of S1P2/4.

Download Full-text

Low (Therapeutic) Dose of Warfarin Is Not Associated with Cognitive and Exploratory Behavior Impairment in Rats: Mechanistic Studies (OR15-01-19)

Current Developments in Nutrition ◽

10.1093/cdn/nzz044.or15-01-19 ◽

2019 ◽

Vol 3 (Supplement_1) ◽

Author(s):

Guylaine Ferland ◽

Pierre Allaire ◽

Bouchra Ouliass

Keyword(s):

Spatial Memory ◽

Cell Signaling ◽

Exploratory Behavior ◽

Low Dose ◽

Sphingolipid Metabolism ◽

Compensatory Mechanisms ◽

Behavioral Impairment ◽

Numerous Cell ◽

Behavior Impairment ◽

The Impact

Abstract Objectives In addition to its role in hemostasis, vitamin K (VK) is involved in brain function through various proteins and sphingolipid metabolism. Warfarin (W), a widely prescribed anticoagulant drug, exerts its beneficial effect in coagulation by partially blocking the recycling of the vitamin. In previous studies, we provided evidence that, when administered in large doses, W leads to cognitive and exploratory behavior impairment, and alteration in the VK dependent proteins Gas6 and protein S (PS) and their downstream pro-survival extracellular signal-regulated (ERK) and serine-threonine (Akt) kinases pathways. In light of its widespread use as oral anticoagulant, the present study aimed to investigate the impact of W on cognition and behavior, Gas6 and PS and their signaling pathways when administered in doses comparable to those used in the clinical setting. Methods Male Wistar rats (n = 14/gp) were fed an AIN-93 based diet containing 750 mcg phylloquinone/kg/d and were randomly allocated to treatment with 0,1 mg W/kg/d (in drinking water) (W group) or not (C group), for 9 wks. Spatial memory (Morris Water Maze) and exploratory behavior (Open Field) were assessed. Gas6, PS, pAkt, pERK, caspases −3 and −12 (apoptosis), brain-derived neurotrophic factor (BDNF), and microglial CD11b/c protein (a marker of inflammation), were assessed by immunoblotting in hippocampus (HPP), frontal cortex (FC), and striatum (STR), three regions involved in cognition. VK contents were determined in these 3 brain regions by HPLC. Group difference was tested by unpaired Student t-test. Results Low dose W had no impact on brain VK concentrations, spatial memory, and exploratory behavior (all P > 0.05). In contrast, W treatment was associated with numerous cell-signaling modulations, namely increased PS, ERK and Akt activity, and caspase −3 and −12 expression, in HPP; increased BDNF in FC and STR; increased expression of CD11bc in STR, (all P < 0.05). Conclusions This study provides evidence that low dose W is not associated with cognitive and behavioral impairment despite numerous cell-signaling modulations that have the potential to be beneficial or detrimental to the brain. Whether these events represent compensatory mechanisms to maintain homeostasis deserves further investigation. Funding Sources Study funded by CIHR.

Download Full-text

DDRE-06. TARGETING THE SPHINGOLIPID BALANCE VIA ACID CERAMIDASE INHIBITION TO DECREASE GROWTH OF TMZ-RESISTANT GLIOBLASTOMA AND BLOCK MIGRATION

Neuro-Oncology ◽

10.1093/neuonc/noab196.290 ◽

2021 ◽

Vol 23 (Supplement_6) ◽

pp. vi75-vi75

Author(s):

Cyntanna Hawkins ◽

Amber Jones ◽

Julia Ziebro ◽

Emily Gordon ◽

Catherine Libby ◽

...

Keyword(s):

Cell Death ◽

The Cancer Genome Atlas ◽

Sphingolipid Metabolism ◽

Acid Ceramidase ◽

Cell Growth And Migration ◽

Sphingosine 1 Phosphate ◽

Sphingosine Kinases ◽

Key Enzyme ◽

Resistant Patient ◽

And Migration

Abstract Dysregulated sphingolipid metabolism is associated with many cancers; allowing cells to evade apoptosis through increases in sphingosine-1-phosphate (S1P) and decreases in ceramides. Ceramides can be hydrolyzed by ceramidases to sphingosine, which can then be phosphorylated by sphingosine kinases to S1P. S1P allows cells to evade apoptosis and increase migration, while shifts toward ceramides favor cell death. Glioblastoma (GBM) exhibits shifts in the sphingolipid balance towards S1P, contributing to chemoresistance and migration. Understanding of sphingolipid metabolism in GBM is still limited, and currently, there are no approved treatments to target the dysregulation. Acid ceramidase (ASAH1), a key enzyme in the production of S1P, is highly expressed in GBM and is associated with worse survival of GBM patients, as per The Cancer Genome Atlas data. To address the altered sphingolipid metabolism and therapeutic resistance in GBM, we explored the efficacy of pharmacologic and genetic inhibition of ASAH1 in both parental and temozolomide (TMZ)-resistant patient-derived xenografts. Cells were infected with ASAH1 shRNA or treated with ASAH1 inhibitors and assessed for cell growth and migration. Our work suggests that pharmacologic inhibition of ASAH1 induces cell death and that this effect is maintained in TMZ-resistant cells. Furthermore, we find a novel role for carmofur, an ASAH1 inhibitor, in the inhibition of GBM migration. Together, these data suggest the potential utility of normalizing the sphingolipid balance in the context of GBM TMZ resistance.

Download Full-text

Targeting the Sphingolipid System as a Therapeutic Direction for Glioblastoma

Cancers ◽

10.3390/cancers12010111 ◽

2020 ◽

Vol 12 (1) ◽

pp. 111 ◽

Cited By ~ 4

Author(s):

Melinda N. Tea ◽

Santosh I. Poonnoose ◽

Stuart M. Pitson

Keyword(s):

Brain Tumor ◽

Cell Signaling ◽

Cellular Responses ◽

Sphingolipid Metabolism ◽

Structural Components ◽

Therapeutic Approaches ◽

Myelin Sheaths ◽

New Therapeutic Approaches ◽

The Brain

Glioblastoma (GBM) is the most commonly diagnosed malignant brain tumor in adults. The prognosis for patients with GBM remains poor and largely unchanged over the last 30 years, due to the limitations of existing therapies. Thus, new therapeutic approaches are desperately required. Sphingolipids are highly enriched in the brain, forming the structural components of cell membranes, and are major lipid constituents of the myelin sheaths of nerve axons, as well as playing critical roles in cell signaling. Indeed, a number of sphingolipids elicit a variety of cellular responses involved in the development and progression of GBM. Here, we discuss the role of sphingolipids in the pathobiology of GBM, and how targeting sphingolipid metabolism has emerged as a promising approach for the treatment of GBM.

Download Full-text