Evidence of lipid rafts based on the partition and dynamic behavior of sphingomyelins

Systematic analysis of the sphingomyelin synthase family in C. elegans

Sphingomyelin (SM) is a major component of mammalian cell membranes and particularly abundant in the myelin sheath that surrounds nerve fibers. Its production is catalyzed by SM synthases SMS1 and SMS2, which interconvert phosphatidylcholine and ceramide to diacylglycerol and SM in the Golgi and at the plasma membrane, respectively. As the lipids participating in this reaction fulfill both structural and signaling functions, SMS enzymes have considerable potential to influence diverse important cellular processes. The nematode Caenorhabditis elegans is an attractive model for studying both animal development and human disease. The organism contains five SMS homologues but none of these have been characterized in any detail. Here, we carried out the first systematic analysis of SMS family members in C. elegans . Using heterologous expression systems, genetic ablation, metabolic labeling and lipidome analyses, we show that C. elegans harbors at least three distinct SM synthases and one ceramide phosphoethanolamine (CPE) synthase. Moreover, C. elegans SMS family members have partially overlapping but also unique subcellular distributions and together occupy all principal compartments of the secretory pathway. Our findings shed light on crucial aspects of sphingolipid metabolism in a valuable animal model and opens avenues for exploring the role of SM and its metabolic intermediates in organismal development.

Eukaryotic Cell Membranes: Structure, Composition, Research Methods and Computational Modelling

This paper deals with the problems encountered in the study of eukaryotic cell membranes. A discussion on the structure and composition of membranes, lateral heterogeneity of membranes, lipid raft formation, and involvement of actin and cytoskeleton networks in the maintenance of membrane structure is included. Modern methods for the study of membranes and their constituent domains are discussed. Various simplified models of biomembranes and lipid rafts are presented. Computer modelling is considered as one of the most important methods. This is stated that from the study of the plasma membrane structure, it is desirable to proceed to the diverse membranes of all organelles of the cell. The qualitative composition and molar content of individual classes of polar lipids, free sterols and proteins in each of these membranes must be considered. A program to create an open access electronic database including results obtained from the membrane modelling of individual cell organelles and the key sites of the membranes, as well as models of individual molecules composing the membranes, has been proposed.

Recently developed glycosphingolipid probes and their dynamic behavior in cell plasma membranes as revealed by single-molecule imaging

Glycosphingolipids, including gangliosides, are representative lipid raft markers that perform a variety of physiological roles in cell membranes. However, studies aimed at revealing their dynamic behavior in living cells are rare, mostly due to a lack of suitable fluorescent probes. Recently, the ganglio-series, lacto-series, and globo-series glycosphingolipid probes, which mimic the behavior of the parental molecules in terms of partitioning to the raft fraction, were developed by conjugating hydrophilic dyes to the terminal glycans of glycosphingolipids using state-of-art entirely chemical-based synthetic techniques. High-speed, single-molecule observation of these fluorescent probes revealed that gangliosides were scarcely trapped in small domains (100 nm in diameter) for more than 5 ms in steady-state cells, suggesting that rafts including gangliosides were always moving and very small. Furthermore, dual-color, single-molecule observations clearly showed that homodimers and clusters of GPI-anchored proteins were stabilized by transiently recruiting sphingolipids, including gangliosides, to form homodimer rafts and the cluster rafts, respectively. In this review, we briefly summarize recent studies, the development of a variety of glycosphingolipid probes as well as the identification of the raft structures including gangliosides in living cells by single-molecule imaging.

Lipidomic profiling of the Brazilian yellow scorpion venom: new insights into inflammatory responses following Tityus serrulatus envenomation

Due to the high prevalence and clinical relevance, scorpionism is a critical public health issue in several Brazilian regions. Tityus serrulatus, commonly known as the Brazilian yellow scorpion, is the most venomous genus found in Brazilian fauna and associated with severe clinical manifestations such as localized pain, hypertension, sweating, tachycardia and complex hyperinflammatory responses. In general, T. serrulatus venom contains a complex mixture of active compounds, including proteins, peptides, and amino acids. Although knowledge of the protein fractions of scorpion venom is available, venom lipid components are not yet comprehensively known. The aim of the present study was to determine and characterize the lipid constituents/profile of the T. serratus venom utilizing liquid chromatography coupled with high-resolution mass spectrometry. Lipid species (164 in total) belonging to 3 different lipid categories, glycerophospholipids, sphingolipids, and glycerolipids, were identified. A further search on MetaCore/MetaDrug platform, which is based upon a manually curated database of molecular interactions, molecular pathways, gene-disease associations, chemical metabolism, and toxicity information, exhibited several metabolic pathways for 24 of previously identified lipid species, including activation of nuclear factor kappa B and oxidative stress pathways. Further several bioactive compounds, such as plasmalogens, lyso-platelet-activating factors, and sphingomyelins, associated with systemic responses triggered by T. serrulatus envenomation were detected. Finally, lipidomic data presented provide advanced and valuable information to better comprehend the mechanisms underlying the complex pathophysiology induced by T. serrulatus envenomation.

Refinement of Singer-Nicolson fluid-mosaic model by microscopy imaging: Lipid rafts and actin-induced membrane compartmentalization

This year celebrates the 50th anniversary of the Singer-Nicolson fluid mosaic model for biological membranes. The next level of sophistication we have achieved for understanding plasma membrane (PM) structures, dynamics, and functions during these 50 years includes the PM interactions with cortical actin filaments and the partial demixing of membrane constituent molecules in the PM, particularly raft domains. Here, first, we summarize our current knowledge of these two structures and emphasize that they are interrelated. Second, we review the structure, molecular dynamics, and function of raft domains, with main focuses on raftophilic glycosylphosphatidylinositol-anchored proteins (GPI-APs) and their signal transduction mechanisms. We pay special attention to the results obtained by single-molecule imaging techniques and other advanced microscopy methods. We also clarify the limitations of present optical microscopy methods for visualizing raft domains, but emphasize that single-molecule imaging techniques can "detect" raft domains associated with molecules of interest in the PM.

Single-Molecule Imaging of Ganglioside Probes in Living Cell Plasma Membranes

Gangliosides play a variety of physiological roles and are one of the most important lipid raft constituents. However, their dynamic behaviors have scarcely been investigated in living cells because of the lack of fluorescent probes that behave like their parental molecules. Recently, fluorescent ganglioside probes that mimic native ganglioside behaviors have been developed. In this chapter, I discuss the recent advances in research related to the lateral localization and dynamic behaviors of gangliosides in the plasma membranes of living cells.

Genetic Tools for Studying the Roles of Sphingolipids in Viral Infections

Sphingolipids are a critical family of membrane lipids with diverse functions in eukaryotic cells, and a growing body of literature supports that these lipids play essential roles during the lifecycles of viruses. While small molecule inhibitors of sphingolipid synthesis and metabolism are widely used, the advent of CRISPR-based genomic editing techniques allows for nuanced exploration into the manners in which sphingolipids influence various stages of viral infections. Here we describe some of these critical considerations needed in designing studies utilizing genomic editing techniques for manipulating the sphingolipid metabolic pathway, as well as the current body of literature regarding how viruses depend on the products of this pathway. Here, we highlight the ways in which sphingolipids affect viruses as these pathogens interact with and influence their host cell and describe some of the many open questions remaining in the field.

Impact of sphingomyelin acyl chain heterogeneity upon properties of raft-like membranes

Sphingomyelin (SM) is a main component of lipid rafts and characteristic of abundance of long and saturated acyl chains. Recently, we reported that fluorescence-labeled lipids including C16:0 and C18:0SMs retained membrane behaviors of inherent lipids. Here, we newly prepared fluorescent SMs with longer acyl chains, C22:0 and C24:1, for observing their partition and diffusion in SM/cholesterol (chol)/dioleoylphosphatidylcholine (DOPC) bilayers. Although fluorescent C24:1SM underwent a uniform distribution between ordered (Lo) and disordered (Ld) phases, other fluorescent SMs with saturated acyl chains were preferentially distributed in the Lo phase. Interestingly, when the acyl chains of fluorescent and membrane SMs are different, distribution of fluorescent SM to the Lo phase was reduced compared to when the acyl chains are the same. This tendency was also observed for C16:0SM/C22:0SM/chol/DOPC quaternary bilayers, where the minor SM was more excluded out of the Lo phase than the major SM. We also found that the coexistence of SMs induces SM efflux out of the Lo phase and simultaneous DOPC influx to the Lo phase, consequently reducing the difference in fluidity between the two phases. These results suggest that physicochemical properties of lipid rafts are regulated by the acyl chain heterogeneity of SMs.

The role of cholesterol in invasion and growth of malaria parasites

Malaria parasites are unicellular eukaryotic pathogens that develop through a complex lifecycle involving two hosts, an anopheline mosquito and a vertebrate host. Throughout this lifecycle, the parasite encounters widely differing conditions and survives in distinct ways, from an intracellular lifestyle in the vertebrate host to exclusively extracellular stages in the mosquito. Although the parasite relies on cholesterol for its growth, the parasite has an ambiguous relationship with cholesterol: cholesterol is required for invasion of host cells by the parasite, including hepatocytes and erythrocytes, and for the development of the parasites in those cells. However, the parasite is unable to produce cholesterol itself and appears to remove cholesterol actively from its own plasma membrane, thereby setting up a cholesterol gradient inside the infected host erythrocyte. Overall a picture emerges in which the parasite relies on host cholesterol and carefully controls its transport. Here, we describe the role of cholesterol at the different lifecycle stages of the parasites.

Inimitable Impacts of Ceramides on Lipid Rafts Formed in Artificial and Natural Cell Membranes

Ceramide is the simplest precursor of sphingolipids and is involved in a variety of biological functions ranging from apoptosis to the immune responses. Although ceramide is a minor constituent of plasma membranes, it drastically increases upon cellular stimulation. However, the mechanistic link between ceramide generation and signal transduction remains unknown. To address this issue, the effect of ceramide on phospholipid membranes has been examined in numerous studies. One of the most remarkable findings of these studies is that ceramide induces the coalescence of membrane domains termed lipid rafts. Thus, it has been hypothesised that ceramide exerts its biological activity through the structural alteration of lipid rafts. In the present article, we first discuss the characteristic hydrogen bond functionality of ceramides. Then, we showed the impact of ceramide on the structures of artificial and cell membranes, including the coalescence of the pre-existing lipid raft into a large patch called a signal platform. Moreover, we proposed a possible structure of the signal platform, in which sphingomyelin/cholesterol-rich and sphingomyelin/ceramide-rich domains coexist. This structure is considered to be beneficial because membrane proteins and their inhibitors are separately compartmentalised in those domains. Considering the fact that ceramide/cholesterol content regulates the miscibility of those two domains in model membranes, the association and dissociation of membrane proteins and their inhibitors might be controlled by the contents of ceramide and cholesterol in the signal platform.

Enterohemorrhagic Escherichia coli and a Fresh View on Shiga Toxin-Binding Glycosphingolipids of Primary Human Kidney and Colon Epithelial Cells and Their Toxin Susceptibility

Enterohemorrhagic Escherichia coli (EHEC) are the human pathogenic subset of Shiga toxin (Stx)-producing E. coli (STEC). EHEC are responsible for severe colon infections associated with life-threatening extraintestinal complications such as the hemolytic-uremic syndrome (HUS) and neurological disturbances. Endothelial cells in various human organs are renowned targets of Stx, whereas the role of epithelial cells of colon and kidneys in the infection process has been and is still a matter of debate. This review shortly addresses the clinical impact of EHEC infections, novel aspects of vesicular package of Stx in the intestine and the blood stream as well as Stx-mediated extraintestinal complications and therapeutic options. Here follows a compilation of the Stx-binding glycosphingolipids (GSLs), globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) and their various lipoforms present in primary human kidney and colon epithelial cells and their distribution in lipid raft-analog membrane preparations. The last issues are the high and extremely low susceptibility of primary renal and colonic epithelial cells, respectively, suggesting a large resilience of the intestinal epithelium against the human-pathogenic Stx1a- and Stx2a-subtypes due to the low content of the high-affinity Stx-receptor Gb3Cer in colon epithelial cells. The review closes with a brief outlook on future challenges of Stx research.

Molecular substructure of the liquid-ordered phase formed by sphingomyelin and cholesterol: sphingomyelin clusters forming nano-subdomains are a characteristic feature

As a model of lipid rafts, the liquid-ordered (Lo) phase formed by sphingomyelin (SM) and cholesterol (Cho) in bilayer membranes has long attracted the attention of biophysics researchers. New approaches and methodologies have led to a better understanding of the molecular basis of the Lo domain structure. This review summarizes studies on model membrane systems consisting of SM/unsaturated phospholipid/Cho implying that the Lo phase contains SM-based nanodomains (or nano-subdomains). Some of the Lo phase properties may be attributed to these nanodomains. Several studies suggest that the nanodomains contain clustered SM molecules packed densely to form gel-phase-like subdomains of single-digit nanometer size at physiological temperatures. Cho and unsaturated lipids located in the Lo phase are likely to be concentrated at the boundaries between the subdomains. These subdomains are not readily detected in the Lo phase formed by saturated phosphatidylcholine (PC) molecules, suggesting that they are strongly stabilized by homophilic interactions specific to SM, e.g., between SM amide groups. This model for the Lo phase is supported by experiments using dihydro-SM, which is thought to have stronger homophilic interactions than SM, as well as by studies using the enantiomer of SM having opposite stereochemistry to SM at the 2 and 3 positions and by some molecular dynamics (MD) simulations of lipid bilayers containing Lo-lipids. Nanosized gel subdomains seem to play an important role in controlling membrane organization and function in biological membranes.

O-GlcNAcylation Inhibits Endocytosis of Amyloid Precursor Protein by Decreasing Its Localization in Lipid Raft Microdomains

Like protein phosphorylation, O-GlcNAcylation is a common post-translational protein modification. We already reported that O-GlcNAcylation of amyloid precursor protein (APP) in response to insulin signaling reduces neurotoxic amyloid-β (Aβ) production via inhibition of APP endocytosis. Internalized APP is delivered to endosomes and lysosomes where Aβ is produced. However, the molecular mechanism involved in the effect of APP O-GlcNAcylation on APP trafficking remains unknown. To investigate the relationship between APP O-GlcNAcylation and APP endocytosis, we tested the effects of insulin on neuroblastoma SH-SY5Y cells overexpressing APP and BACE1, and cultured rat hippocampal neurons. The present study showed that APP O-GlcNAcylation translocated APP from lipid raft to non-raft microdomains in the plasma membrane by using immunocytochemistry and discontinuous sucrose gradients method. By using the biotinylation method, we also found that APP preferentially underwent endocytosis from lipid rafts and that the amount of internalized APP from lipid rafts was specifically reduced by O-GlcNAcylation. These results indicate that O-GlcNAcylation can regulate lipid raft-dependent APP endocytosis via translocation of APP into non-raft microdomains. Our findings showed a new functional role of O-GlcNAcylation for the regulation of APP trafficking, offering new mechanistic insight for Aβ production.

Human breast milk as source of sphingolipids for newborns: comparison with infant formulas and commercial cow's milk

Background

In the past two decades, sphingolipids have become increasingly appreciated as bioactive molecules playing important roles in a wide array of pathophysiology mechanisms. Despite advances in the field, sphingolipids as nutrients remain little explored. Today the research is starting to move towards the study of the sphingomyelin content in human breast milk, recommended for feeding infants.

Methods

In the present study, we performed a lipidomic analysis in human breast milk in relation with maternal diet during pregnancy, in infant formulas, and in commercial whole and semi-skimmed milks for adults. Mediterranean, carnivorous and vegetarian diets were considered.

Results

The results showed that total sphingomyelin, ceramide and dihydroceramide species are independent on the diet. Interestingly, the milk sphingolipid composition is species-specific. In fact, infant formulas and commercial milks for adults have a lower level of total sphingomyelin and ceramide content than human breast milk with very different composition of each sphingolipid species.

Conclusions

We conclude that human breast milk is a better source of sphingolipids than infant formulas for baby nutrition with potential implications for the brain development and cognitive functions.

The silence of the fats: A MAM's story about Alzheimer

The discovery of contact sites was a breakthrough in cell biology. We have learned that an organelle cannot function in isolation, and that many cellular functions depend on communication between two or more organelles. One such contact site results from the close apposition of the endoplasmic reticulum (ER) and mitochondria, known as mitochondria-associated ER membranes (MAMs). These intracellular lipid rafts serve as hubs for the regulation of cellular lipid and calcium homeostasis, and a growing body of evidence indicates that MAM domains modulate cellular function in both health and disease. Indeed, MAM dysfunction has been described as a key event in Alzheimer disease (AD) pathogenesis. Our most recent work shows that, by means of its affinity for cholesterol, APP-C99 accumulates in MAM domains of the ER and induces the uptake of extracellular cholesterol as well as its trafficking from the plasma membrane to the ER. As a result, MAM functionality becomes chronically upregulated while undergoing continual turnover. The goal of this review is to discuss the consequences of C99 elevation in AD, specifically the upregulation of cholesterol trafficking and MAM activity, which abrogate cellular lipid homeostasis and disrupt the lipid composition of cellular membranes. Overall, we present a novel framework for AD pathogenesis that can be linked to the many complex alterations that occur during disease progression, and that may open a door to new therapeutic strategies.

Assembly formation of minor dihydrosphingomyelin in sphingomyelin-rich ordered membrane domains

The lipidome of mammalian cells not only contain sphingomyelin (SM) but also, as a minor component, dihydrosphongomyelin (DHSM), in which the double bond at C4–C5 in the sphingosine base is reduced to a single-bond linkage. It has been indicated that DHSM forms ordered domains more effectively than SM due to its greater potential to induce intermolecular hydrogen bonds. However, direct information on partition and dynamic behaviors of DHSM in raft-like liquid-ordered (L_o) and non-raft-like liquid-disordered (L_d) phase-segregated membranes has been lacking. In the present study, we prepared fluorescent derivatives of DHSM and compared their behaviors to those of fluorescent SM and phosphatidylcholine (PC) derivatives. Fluorescence microscopy showed that DHSM is more preferentially localized to the L_o domains in the L_o/L_d phase-segregated giant unilamellar vesicles than SM and PC. Most importantly, diffusion coefficient measurements indicated that DHSM molecules form DHSM-condensed assembly inside the SM-rich L_o domain of the SM/dioleoylphosphatidylcholine/cholesterol system even when DHSM accounts for 1–3.3 mol% of total lipids. Such heterogeneous distribution of DHSM in the SM-rich L_o domains was further confirmed by inter-lipid FRET experiments. This study provides new insights into the biological functions and significance of minor component DHSM in lipid rafts.

Valid Presumption of Shiga Toxin-Mediated Damage of Developing Erythrocytes in EHEC-Associated Hemolytic Uremic Syndrome

The global emergence of clinical diseases caused by enterohemorrhagic Escherichia coli (EHEC) is an issue of great concern. EHEC release Shiga toxins (Stxs) as their key virulence factors, and investigations on the cell-damaging mechanisms toward target cells are inevitable for the development of novel mitigation strategies. Stx-mediated hemolytic uremic syndrome (HUS), characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal injury, is the most severe outcome of an EHEC infection. Hemolytic anemia during HUS is defined as the loss of erythrocytes by mechanical disruption when passing through narrowed microvessels. The formation of thrombi in the microvasculature is considered an indirect effect of Stx-mediated injury mainly of the renal microvascular endothelial cells, resulting in obstructions of vessels. In this review, we summarize and discuss recent data providing evidence that HUS-associated hemolytic anemia may arise not only from intravascular rupture of erythrocytes, but also from the extravascular impairment of erythropoiesis, the development of red blood cells in the bone marrow, via direct Stx-mediated damage of maturing erythrocytes, leading to “non-hemolytic” anemia.

Membrane Compartmentalization and Scaffold Proteins in Leukocyte Migration

Leukocyte migration across vessels into and within peripheral and lymphoid tissues is essential for host defense against invading pathogens. Leukocytes are specialized in sensing a variety of guidance cues and to integrate environmental stimuli to navigate in a timely and spatially controlled manner. These extracellular signals must be transmitted across the leukocyte’s plasma membrane in a way that intracellular signaling cascades enable directional cell movement. Therefore, the composition of the membrane in concert with proteins that influence the compartmentalization of the plasma membrane or contribute to delineate intracellular signaling molecules are key in controlling leukocyte navigation. This becomes evident by the fact that mislocalization of membrane proteins is known to deleteriously affect cellular functions that may cause diseases. In this review we summarize recent advances made in the understanding of how membrane cholesterol levels modulate chemokine receptor signaling and hence leukocyte trafficking. Moreover, we provide an overview on the role of membrane scaffold proteins, particularly tetraspanins, flotillins/reggies, and caveolins in controlling leukocyte migration both in vitro and in vivo.

Lipid rafts and neurodegeneration: structural and functional roles in physiologic aging and neurodegenerative diseases

Lipid rafts are small, dynamic membrane areas characterized by the clustering of selected membrane lipids as the result of the spontaneous separation of glycolipids, sphingolipids, and cholesterol in a liquid-ordered phase. The exact dynamics underlying phase separation of membrane lipids in the complex biological membranes are still not fully understood. Nevertheless, alterations in the membrane lipid composition affect the lateral organization of molecules belonging to lipid rafts. Neural lipid rafts are found in brain cells, including neurons, astrocytes, and microglia, and are characterized by a high enrichment of specific lipids depending on the cell type. These lipid rafts seem to organize and determine the function of multiprotein complexes involved in several aspects of signal transduction, thus regulating the homeostasis of the brain. The progressive decline of brain performance along with physiological aging is at least in part associated with alterations in the composition and structure of neural lipid rafts. In addition, neurodegenerative conditions, such as lysosomal storage disorders, multiple sclerosis, and Parkinson's, Huntington's, and Alzheimer's diseases, are frequently characterized by dysregulated lipid metabolism, which in turn affects the structure of lipid rafts. Several events underlying the pathogenesis of these diseases appear to depend on the altered composition of lipid rafts. Thus, the structure and function of lipid rafts play a central role in the pathogenesis of many common neurodegenerative diseases.jlr;61/5/636/F1F1f1.

The fat brain

PURPOSE OF REVIEW

The purpose of this brief review is to gain an understanding on the multiple roles that lipids exert on the brain, and to highlight new ideas in the impact of lipid homeostasis in the regulation of synaptic transmission.

RECENT FINDINGS

Recent data underline the crucial function of lipid homeostasis in maintaining neuronal function and synaptic plasticity. Moreover, new advances in analytical approaches to study lipid classes and species is opening a new door to understand and monitor how alterations in lipid pathways could shed new light into the pathogenesis of neurodegeneration.

SUMMARY

Lipids are one of the most essential elements of the brain. However, our understanding of the role of lipids within the central nervous system is still largely unknown. Identifying the molecular mechanism (s) by which lipids can regulate neuronal transmission represents the next frontier in neuroscience, and a new challenge in our understanding of the brain and the mechanism(s) behind neurological disorders.

Phospholipases in neuronal function: A role in learning and memory?

Despite the human brain being made of nearly 60% fat, the vast majority of studies on the mechanisms of neuronal communication which underpin cognition, memory and learning, primarily focus on proteins and/or (epi)genetic mechanisms. Phospholipids are the main component of all cellular membranes and function as substrates for numerous phospholipid-modifying enzymes, including phospholipases, which release free fatty acids (FFAs) and other lipid metabolites that can alter the intrinsic properties of the membranes, recruit and activate critical proteins, and act as lipid signalling molecules. Here, we will review brain specific phospholipases, their roles in membrane remodelling, neuronal function, learning and memory, as well as their disease implications. In particular, we will highlight key roles of unsaturated FFAs, particularly arachidonic acid, in neurotransmitter release, neuroinflammation and memory. In light of recent findings, we will also discuss the emerging role of phospholipase A₁ and the creation of saturated FFAs in the brain.

The Squeaky Yeast Gets Greased: The Roles of Host Lipids in the Clearance of Pathogenic Fungi

Fungal infections remain a global health threat with high morbidity and mortality. The human immune system must, therefore, perpetually defend against invasive fungal infections. Phagocytosis is critical for the clearance of fungal pathogens, as this cellular process allows select immune cells to internalize and destroy invading fungal cells. While much is known about the protein players that enable phagocytosis, the various roles that lipids play during this fundamental innate immune process are still being illuminated. In this review, we describe recent discoveries that shed new light on the mechanisms by which host lipids enable the phagocytic uptake and clearance of fungal pathogens.

Preparation and Membrane Distribution of Fluorescent Derivatives of Ceramide

Ceramide is a bioactive lipid with significant roles in several biological processes including cell proliferation, apoptosis, and raft formation. Although fluorescent derivatives of ceramide are required to probe the behavior of ceramide in cells and cell membranes, commercial fluorescent ceramide derivatives do not reproduce the membrane behavior of native ceramide because of the introduction of bulky fluorophores in the acyl chain. Recently, we developed novel fluorescent analogs of sphingomyelin in which the hydrophilic fluorophores, ATTO488 and ATTO594, are attached to the polar head of sphingomyelin via a nonaethylene glycol linker and demonstrated that their partition and dynamic behaviors in bilayer membranes are similar to native sphingomyelin. In this report, by extending the concept used for the development of fluorescent analogs of sphingomyelin, we prepared novel fluorescent ceramides that exhibit membrane behaviors similar to native ceramide and succeeded in visualizing ceramide-rich membrane domains segregated from ceramide-poor domains.