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1.
J Nutr ; 152(8): 1991-2002, 2022 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-35679100

RESUMO

BACKGROUND: Although dietary DHA alleviates Toll-like receptor (TLR)-associated chronic inflammation in fish, the underlying mechanism is not well understood. OBJECTIVES: This study aimed to explore the role of Tlr22 in the innate immunity of large yellow croaker and investigate the anti-inflammatory effects of DHA on Tlr22-triggered inflammation. METHODS: Head kidney-derived macrophages of croaker and HEK293T cells were or were not pretreated with 100 µM DHA for 10 h prior to polyinosinic-polycytidylic acid (poly I:C) stimulation. We executed qRT-PCR, immunoblotting, and lipidomic analysis to examine the impact of DHA on Tlr22-triggered inflammation and membrane lipid composition. In vivo, croakers (12.03 ± 0.05 g) were fed diets containing 0.2% [control (Ctrl)], 0.8%, and 1.6% DHA for 8 wk before injection with poly I:C. Inflammatory genes expression and rafts-related lipids and protein expression were measured in the head kidney. Data were analyzed by ANOVA or Student t test. RESULTS: The activation of Tlr22 by poly I:C induced inflammation, and DHA diminished Tlr22-targeted inflammatory gene expression by 56-73% (P ≤ 0.05). DHA reduced membrane sphingomyelin (SM) and SFA-containing phosphatidylcholine (SFA-PC) contents, as well as lipid raft marker caveolin 1 amounts. Furthermore, lipid raft disruption suppressed Tlr22-induced Nf-κb and interferon h activation and p65 nuclear translocation. In vivo, expression of Tlr22 target inflammatory genes was 32-64% lower in the 1.6% DHA group than in the Ctrl group upon poly I:C injection (P ≤ 0.05). Also, the 1.6% DHA group showed a reduction in membrane SM and SFA-PC contents, accompanied by a decrease in caveolin 1 amounts, compared with the Ctrl group. CONCLUSIONS: The activation of Tlr22 signaling depends on lipid rafts, and DHA ameliorates the Tlr22-triggered inflammation in both head kidney and head kidney-derived macrophages of croaker partially by altering membrane SMs and SFA-PCs that are required for lipid raft organization.


Assuntos
Ácidos Docosa-Hexaenoicos , Perciformes , Animais , Caveolina 1/metabolismo , Caveolina 1/farmacologia , Ácidos Docosa-Hexaenoicos/metabolismo , Ácidos Docosa-Hexaenoicos/farmacologia , Células HEK293 , Humanos , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Microdomínios da Membrana/metabolismo , Fosfatidilcolinas/metabolismo , Poli I/metabolismo , Poli I/farmacologia , Esfingomielinas/metabolismo , Receptores Toll-Like/genética , Receptores Toll-Like/metabolismo
2.
J Mol Neurosci ; 72(7): 1482-1499, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35727525

RESUMO

Niemann-Pick type A disease (NPA) is a rare lysosomal storage disorder caused by mutations in the gene coding for the lysosomal enzyme acid sphingomyelinase (ASM). ASM deficiency leads to the consequent accumulation of its uncatabolized substrate, the sphingolipid sphingomyelin (SM), causing severe progressive brain disease. To study the effect of the aberrant lysosomal accumulation of SM on cell homeostasis, we loaded skin fibroblasts derived from a NPA patient with exogenous SM to mimic the levels of accumulation characteristic of the pathological neurons. In SM-loaded NPA fibroblasts, we found the blockage of the autophagy flux and the impairment of the mitochondrial compartment paralleled by the altered transcription of several genes, mainly belonging to the electron transport chain machinery and to the cholesterol biosynthesis pathway. In addition, SM loading induces the nuclear translocation of the transcription factor EB that promotes the lysosomal biogenesis and exocytosis. Interestingly, we obtained similar biochemical findings in the brain of the NPA mouse model lacking ASM (ASMKO mouse) at the neurodegenerative stage. Our work provides a new in vitro model to study NPA etiopathology and suggests the existence of a pathogenic lysosome-plasma membrane axis that with an impairment in the mitochondrial activity is responsible for the cell death.


Assuntos
Doença de Niemann-Pick Tipo A , Doenças de Niemann-Pick , Animais , Apoptose , Lisossomos/metabolismo , Camundongos , Mitocôndrias/metabolismo , Doença de Niemann-Pick Tipo A/genética , Doença de Niemann-Pick Tipo A/patologia , Doenças de Niemann-Pick/metabolismo , Doenças de Niemann-Pick/patologia , Esfingomielinas/metabolismo , Esfingomielinas/farmacologia
3.
Adv Exp Med Biol ; 1372: 77-86, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35503176

RESUMO

The sphingomyelin synthase (SMS) gene family has three members: SMS1 and SMS2 have SM synthase activity, while SMS-related protein (SMSr) has no SM synthase activity but has ceramide phosphorylethanolamine (CPE) synthase activity in vitro. Recently, we found that SMS family members are a group of phospholipase Cs (PLC). SMS1 and SMS2 are two phosphatidylcholine (PC)-PLCs and SMSr is a phosphatidylethanolamine (PE)-PLC. SMS family members not only influence SM levels but also influence the levels of diacylglycerol (DAG), PC, PE, and glycosphingolipids, thus influencing cell functions. In this chapter, we will discuss the recent progress in the research field of SMS family and will focus on its impact on metabolic diseases.


Assuntos
Fosfolipases , Esfingomielinas , Fosfatidilcolinas/metabolismo , Esfingomielinas/genética , Esfingomielinas/metabolismo , Transferases (Outros Grupos de Fosfato Substituídos)/genética , Transferases (Outros Grupos de Fosfato Substituídos)/metabolismo , Fosfolipases Tipo C/metabolismo
4.
Nat Commun ; 13(1): 1875, 2022 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-35388011

RESUMO

Lysosomes are vital organelles vulnerable to injuries from diverse materials. Failure to repair or sequester damaged lysosomes poses a threat to cell viability. Here we report that cells exploit a sphingomyelin-based lysosomal repair pathway that operates independently of ESCRT to reverse potentially lethal membrane damage. Various conditions perturbing organelle integrity trigger a rapid calcium-activated scrambling and cytosolic exposure of sphingomyelin. Subsequent metabolic conversion of sphingomyelin by neutral sphingomyelinases on the cytosolic surface of injured lysosomes promotes their repair, also when ESCRT function is compromised. Conversely, blocking turnover of cytosolic sphingomyelin renders cells more sensitive to lysosome-damaging drugs. Our data indicate that calcium-activated scramblases, sphingomyelin, and neutral sphingomyelinases are core components of a previously unrecognized membrane restoration pathway by which cells preserve the functional integrity of lysosomes.


Assuntos
Cálcio , Esfingomielinas , Cálcio/metabolismo , Citosol/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Lisossomos/metabolismo , Esfingomielinas/metabolismo
5.
Int J Mol Sci ; 23(7)2022 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-35409383

RESUMO

The ceramide transport protein (CERT) delivers ceramide from the endoplasmic reticulum (ER) to the Golgi apparatus, where ceramide is converted to sphingomyelin (SM). The function of CERT is regulated in two distinct phosphorylation-dependent events: multiple phosphorylations in a serine-repeat motif (SRM) and phosphorylation of serine 315 residue (S315). Pharmacological inhibition of SM biosynthesis results in an increase in SRM-dephosphorylated CERT, which serves as an activated form, and an enhanced phosphorylation of S315, which augments the binding of CERT to ER-resident VAMP-associated protein (VAP), inducing the full activation of CERT to operate at the ER-Golgi membrane contact sites (MCSs). However, it remains unclear whether the two phosphorylation-dependent regulatory events always occur coordinately. Here, we describe that hyperosmotic stress induces S315 phosphorylation without affecting the SRM-phosphorylation state. Under hyperosmotic conditions, the binding of CERT with VAP-A is enhanced in an S315 phosphorylation-dependent manner, and this increased binding occurs throughout the ER rather than restrictedly at the ER-Golgi MCSs. Moreover, we found that de novo synthesis of SM with very-long acyl chains preferentially increases via a CERT-independent mechanism under hyperosmotic-stressed cells, providing an insight into a CERT-independent ceramide transport pathway for de novo synthesis of SM.


Assuntos
Proteínas de Transporte , Ceramidas , Transporte Biológico , Proteínas de Transporte/metabolismo , Ceramidas/metabolismo , Retículo Endoplasmático/metabolismo , Complexo de Golgi/metabolismo , Fosforilação , Serina/metabolismo , Esfingomielinas/metabolismo
6.
Biochem Biophys Res Commun ; 611: 14-18, 2022 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-35472605

RESUMO

Macroscopic lipid observation in the organs of living small animals has not been realized. Here, we visualized sphingomyelin (SM) in the intestines of living mice using an SM-binding protein (EqtII-EGFP-His) under two-photon microscopy. The SM was identified as 10 µm spots in glands of the lamina propria of the mucosa in the large and small intestines. The spots vertically penetrated from the serosa toward the mucosal side. At the edge of the mucosal side in the small intestine, these spots connected with each other and formed horizontal lines. For the large intestine, the horizontal lines became a surface, indicating that SM covered the whole crypt membrane. Detailed observation revealed thin SM-positive lines that connected the spots and the blood vessels in the small intestine. Thus, SM exists at crypt surfaces and inside crypts of the intestines and can regulate the functions of the digestion system.


Assuntos
Microscopia , Esfingomielinas , Animais , Mucosa Intestinal/metabolismo , Intestino Delgado/metabolismo , Camundongos , Esfingomielinas/metabolismo
7.
J Membr Biol ; 255(2-3): 225-236, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35467110

RESUMO

Caveolin-1 is one of the main protein components of caveolae that acts as a mechanosensor at the cell membrane. The interactions of caveolin-1 with membranes have been shown to lead to complex effects such as curvature and the clustering of specific lipids. Here, we review the emerging concepts on the molecular interactions of caveolin-1, with a focus on insights from coarse-grain molecular dynamics simulations. Consensus structural models of caveolin-1 report a helix-turn-helix core motif with flanking domains of higher disorder that could be membrane composition dependent. Caveolin-1 appears to be mainly surface-bound and does not embed very deep in the membrane to which it is bound. The most interesting aspect of caveolin-1 membrane binding is the interplay of cholesterol clustering and membrane curvature. Although cholesterol has been reported to cluster in the vicinity of caveolin-1 by several approaches, simulations show that the clustering is maximal in membrane leaflet opposing the surface-bound caveolin-1. The intrinsic negative curvature of cholesterol appears to stabilize the negative curvature in the opposing leaflet. In fact, the simulations show that blocking cholesterol clustering (through artificial position restraints) blocks membrane curvature, and vice versa. Concomitant with cholesterol clustering is sphingomyelin clustering, again in the opposing leaflet, but in a concentration-dependent manner. The differential stress due to caveolin-1 binding and the inherent asymmetry of the membrane leaflets could be the determinant for membrane curvature and needs to be further probed. The review is an important step to reconcile the molecular level details emerging from simulations with the mesoscopic details provided by state of the art experimental approaches.


Assuntos
Caveolina 1 , Bicamadas Lipídicas , Caveolina 1/metabolismo , Membrana Celular/metabolismo , Colesterol/química , Bicamadas Lipídicas/química , Esfingomielinas/metabolismo
8.
J Cell Biol ; 221(4)2022 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-35319770

RESUMO

Epithelial cells are constantly exposed to osmotic stress. The influx of water molecules into the cell in a hypo-osmotic environment increases plasma membrane tension as it rapidly expands. Therefore, the plasma membrane must be supplied with membrane lipids since expansion beyond its elastic limit will cause the cell to rupture. However, the molecular mechanism to maintain a constant plasma membrane tension is not known. In this study, we found that the apical membrane selectively expands when epithelial cells are exposed to hypo-osmotic stress. This requires the activation of mTORC2, which enhances the transport of secretory vesicles containing sphingomyelin, the major lipid of the apical membrane. We further show that the mTORC2-Rab35 axis plays an essential role in the defense against hypotonic stress by promoting the degradation of the actin cortex through the up-regulation of PI(4,5)P2 metabolism, which facilitates the apical tethering of sphingomyelin-loaded vesicles to relieve plasma membrane tension.


Assuntos
Esfingomielinas , Morte Celular , Membrana Celular/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Pressão Osmótica/fisiologia , Esfingomielinas/metabolismo
9.
J Agric Food Chem ; 70(10): 3228-3238, 2022 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-35229592

RESUMO

Ceramide is a natural functional ingredient as food additive and medicine that has attracted extensive attention in the food, medical, and cosmetic industries. Here, we developed a biotechnological strategy based on a recombinant whole-cell biocatalyst for efficiently producing ceramide from crude soybean oil sediment (CSOS) waste. A novel phospholipase C (PLCac) from Acinetobacter calcoaceticus isolated from soil samples was identified and characterized. Furthermore, recombinant Komagataella phaffii displaying PLCac (dPLCac) on the cell surface was constructed as a whole-cell biocatalyst with better thermostability (30-60 °C) and pH stability (8.0-10.0) to successfully produce ceramide. After synergistical optimization of reaction time and dPLCac dose, the ceramide yield of hydrolyzing from CSOS using dPLCac was 51% (the theoretical maximum yield of converting sphingomyelin, ∼70%) and the relative yield was over 50% after seven consecutive 4 h batches under the optimized conditions. Our study provides a potentially promising strategy for the commercial production of ceramide.


Assuntos
Ceramidas , Óleo de Soja , Óleo de Soja/química , Esfingomielinas/metabolismo , Fosfolipases Tipo C/metabolismo
10.
Cells ; 11(5)2022 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-35269496

RESUMO

The recent discovery demonstrating that the leakage of cathepsin B from mitotic lysosomes assists mitotic chromosome segregation indicates that lysosomal membrane integrity can be spatiotemporally regulated. Unlike many other organelles, structural and functional alterations of lysosomes during mitosis remain, however, largely uncharted. Here, we demonstrate substantial differences in lysosomal proteome, lipidome, size, and pH between lysosomes that were isolated from human U2OS osteosarcoma cells either in mitosis or in interphase. The combination of pharmacological synchronization and mitotic shake-off yielded ~68% of cells in mitosis allowing us to investigate mitosis-specific lysosomal changes by comparing cell populations that were highly enriched in mitotic cells to those mainly in the G1 or G2 phases of the cell cycle. Mitotic cells had significantly reduced levels of lysosomal-associated membrane protein (LAMP) 1 and the active forms of lysosomal cathepsin B protease. Similar trends were observed in levels of acid sphingomyelinase and most other lysosomal proteins that were studied. The altered protein content was accompanied by increases in the size and pH of LAMP2-positive vesicles. Moreover, mass spectrometry-based shotgun lipidomics of purified lysosomes revealed elevated levels of sphingolipids, especially sphingomyelin and hexocylceramide, and lysoglyserophospholipids in mitotic lysosomes. Interestingly, LAMPs and acid sphingomyelinase have been reported to stabilize lysosomal membranes, whereas sphingomyelin and lysoglyserophospholipids have an opposite effect. Thus, the observed lysosomal changes during the cell cycle may partially explain the reduced lysosomal membrane integrity in mitotic cells.


Assuntos
Catepsina B , Esfingomielina Fosfodiesterase , Catepsina B/metabolismo , Segregação de Cromossomos , Humanos , Proteína 1 de Membrana Associada ao Lisossomo/metabolismo , Lisossomos/metabolismo , Mitose , Esfingomielina Fosfodiesterase/metabolismo , Esfingomielinas/metabolismo , Esfingomielinas/farmacologia
11.
Am J Physiol Cell Physiol ; 322(5): C948-C959, 2022 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-35294847

RESUMO

Sphingomyelin phosphodiesterase 1 (SMPD1) converts sphingomyelin into ceramide and phosphocholine; hence, loss of SMPD1 function causes abnormal accumulation of sphingomyelin in lysosomes, which results in the lipid-storage disorder Niemann-Pick disease (types A and B). SMPD1 activity is dependent on zinc, which is coordinated at the active site of the enzyme, and although SMPD1 has been suggested to acquire zinc at the sites where the enzyme is localized, precisely how SMPD1 acquires zinc remains to be clarified. Here, we addressed this using a gene-disruption/reexpression strategy. Our results revealed that Zn transporter 5 (ZNT5)-ZNT6 heterodimers and ZNT7 homodimers, which localize in the compartments of the early secretory pathway, play essential roles in SMPD1 activation. Both ZNT complexes contribute to cellular sphingolipid metabolism by activating SMPD1 because cells lacking the functions of the two complexes exhibited a reduced ceramide to sphingomyelin content ratio in terms of their dominant molecular species and an increase in the sphingomyelin content in terms of three minor species. Moreover, mutant cells contained multilamellar body-like structures, indicative of membrane stacking and accumulation, in the cytoplasm. These findings provide novel insights into the molecular mechanism underlying the activation of SMPD1, a key enzyme in sphingolipid metabolism.


Assuntos
Esfingolipídeos , Esfingomielina Fosfodiesterase , Ceramidas , Via Secretória , Esfingolipídeos/metabolismo , Esfingomielina Fosfodiesterase/genética , Esfingomielina Fosfodiesterase/metabolismo , Esfingomielinas/metabolismo , Zinco/metabolismo
12.
FEBS Lett ; 596(8): 1029-1036, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35253212

RESUMO

Sticholysins are pore-forming toxins produced by the sea anemone Stichodactyla helianthus. When they encounter a sphingomyelin-containing membrane, these proteins bind to it and oligomerize, a process that ends in pore formation. Mounting evidence indicates that StnII can favour the activity of StnI. Previous results have shown that these two isotoxins can oligomerize together. Furthermore, StnII appeared to potentiate the activity of StnI through the membrane-binding step of the process. Hence, isotoxin interaction should occur prior to membrane encounter. Here, we have used analytical ultracentrifugation to investigate the oligomerization of Stns in solution, both separately and together. Our results indicate that while StnI seems to be more prone to oligomerize in water solution than StnII, a small percentage of StnII in StnI-StnII mixtures promotes oligomerization.


Assuntos
Anêmonas-do-Mar , Animais , Membranas/metabolismo , Compostos Orgânicos , Anêmonas-do-Mar/metabolismo , Esfingomielinas/metabolismo
13.
J Dairy Sci ; 105(3): 1929-1939, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34998560

RESUMO

Ceramide-containing phospholipids improve skin hydration and barrier function and are ideal for use in skin care products. In this study, we evaluated the photoprotective effect of milk phospholipids on the skin condition of UVB-irradiated hairless mice. Skin parameters were assessed following oral administration of milk phospholipids. The UVB irradiation induced photoaging in mice. The animals were divided into 5 groups: a control group (oral administration of saline with no UBV irradiation), UVB group (oral administration of saline with UVB irradiation), and 3 UVB irradiation groups receiving the milk phospholipids at 3 different concentrations of oral administration, 50 mg/kg (ML group), 100 mg/kg (MM group), and 150 mg/kg (MH group), for 8 wk. An increase in skin hydration and transepidermal water loss were improved in the 150 mg/kg of milk phospholipid-administered group. Hematoxylin and eosin staining revealed a decrease in epidermal thickness in the milk phospholipid-administered groups (50, 100, and 150 mg/kg of body weight). In particular, the 100 and 150 mg/kg groups showed significant changes in the area, length, and depth of the wrinkles compared with the UVB group. Moreover, the gene expression of matrix metalloproteins was attenuated, and that of proinflammatory cytokines, especially tumor necrosis factor-α, was significantly reduced in the milk phospholipid-administered groups than in the UVB group. The reduced ceramide and increased sphingosine-1-phosphate levels in the skin tissue due to UVB exposure were restored to levels similar to those of the control group following milk phospholipid administration. These results were confirmed to be due to the downregulation of protein expression of nuclear factor kappa-B (NF-κB) and phosphorylated IκB-α (inhibitor of κB α). Collectively, oral administration of milk phospholipids improves skin health through a synergistic effect on photoprotective activity.


Assuntos
NF-kappa B , Esfingomielinas , Animais , Camundongos , Camundongos Pelados , Leite/metabolismo , NF-kappa B/metabolismo , Fosfolipídeos/metabolismo , Pele/metabolismo , Esfingomielinas/metabolismo , Raios Ultravioleta
14.
Cell Rep ; 38(4): 110298, 2022 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-35081353

RESUMO

The reverse cholesterol transport pathway is responsible for the maintenance of human cholesterol homeostasis, an imbalance of which usually leads to atherosclerosis. As a key component of this pathway, the ATP-binding cassette transporter ABCG1 forwards cellular cholesterol to the extracellular acceptor nascent high-density lipoprotein (HDL). Here, we report a 3.26-Å cryo-electron microscopy structure of cholesterol-bound ABCG1 in an inward-facing conformation, which represents a turnover condition upon ATP binding. Structural analyses combined with functional assays reveals that a cluster of conserved hydrophobic residues, in addition to two sphingomyelins, constitute a well-defined cholesterol-binding cavity. The exit of this cavity is closed by three pairs of conserved Phe residues, which constitute a hydrophobic path for the release of cholesterol in an acceptor concentration-dependent manner. Overall, we propose an ABCG1-driven cholesterol transport cycle initiated by sphingomyelin-assisted cholesterol recruitment and accomplished by the release of cholesterol to HDL.


Assuntos
Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/química , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/ultraestrutura , Colesterol/metabolismo , Microscopia Crioeletrônica , Humanos , Esfingomielinas/metabolismo
15.
J Virol ; 96(5): e0181321, 2022 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-35020471

RESUMO

Influenza A virus (IAV) is a global health threat. The cellular endocytic machineries harnessed by IAV remain elusive. Here, by tracking single IAV particles and quantifying the internalized IAV, we found that sphingomyelin (SM)-sequestered cholesterol, but not accessible cholesterol, is essential for the clathrin-mediated endocytosis (CME) of IAV. The clathrin-independent endocytosis of IAV is cholesterol independent, whereas the CME of transferrin depends on SM-sequestered cholesterol and accessible cholesterol. Furthermore, three-color single-virus tracking and electron microscopy showed that the SM-cholesterol complex nanodomain is recruited to the IAV-containing clathrin-coated structure (CCS) and facilitates neck constriction of the IAV-containing CCS. Meanwhile, formin-binding protein 17 (FBP17), a membrane-bending protein that activates actin nucleation, is recruited to the IAV-CCS complex in a manner dependent on the SM-cholesterol complex. We propose that the SM-cholesterol nanodomain at the neck of the CCS recruits FBP17 to induce neck constriction by activating actin assembly. These results unequivocally show the physiological importance of the SM-cholesterol complex in IAV entry. IMPORTANCE IAV infects cells by harnessing cellular endocytic machineries. A better understanding of the cellular machineries used for its entry might lead to the development of antiviral strategies and would also provide important insights into physiological endocytic processes. This work demonstrated that a special pool of cholesterol in the plasma membrane, SM-sequestered cholesterol, recruits FBP17 for the constriction of clathrin-coated pits in IAV entry. Meanwhile, the clathrin-independent cell entry of IAV is cholesterol independent. The internalization of transferrin, the gold-standard cargo endocytosed solely via CME, is much less dependent on the SM-cholesterol complex. These results provide new insights into IAV infection and the pathway/cargo-specific involvement of the cholesterol pool(s).


Assuntos
Colesterol , Vesículas Revestidas por Clatrina , Proteínas de Ligação a Ácido Graxo , Forminas , Vírus da Influenza A , Internalização do Vírus , Actinas/metabolismo , Animais , Colesterol/metabolismo , Vesículas Revestidas por Clatrina/metabolismo , Vesículas Revestidas por Clatrina/virologia , Endocitose/fisiologia , Proteínas de Ligação a Ácido Graxo/metabolismo , Forminas/metabolismo , Vírus da Influenza A/metabolismo , Domínios Proteicos , Esfingomielinas/metabolismo , Transferrinas/metabolismo
16.
J Cell Sci ; 135(5)2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-34881783

RESUMO

Male and female Plasmodium falciparum gametocytes are the parasite lifecycle stage responsible for transmission of malaria from the human host to the mosquito vector. Not only are gametocytes able to survive in radically different host environments, but they are also precursors for male and female gametes that reproduce sexually soon after ingestion by the mosquito. Here, we investigate the sex-specific lipid metabolism of gametocytes within their host red blood cell. Comparison of the male and female lipidome identifies cholesteryl esters and dihydrosphingomyelin enrichment in female gametocytes. Chemical inhibition of each of these lipid types in mature gametocytes suggests dihydrosphingomyelin synthesis but not cholesteryl ester synthesis is important for gametocyte viability. Genetic disruption of each of the two sphingomyelin synthase genes points towards sphingomyelin synthesis contributing to gametocytogenesis. This study shows that gametocytes are distinct from asexual stages, and that the lipid composition is also vastly different between male and female gametocytes, reflecting the different cellular roles these stages play. Taken together, our results highlight the sex-specific nature of gametocyte lipid metabolism, which has the potential to be targeted to block malaria transmission. This article has an associated First Person interview with the first author of the paper.


Assuntos
Malária Falciparum , Plasmodium falciparum , Animais , Feminino , Humanos , Estágios do Ciclo de Vida/fisiologia , Metabolismo dos Lipídeos , Masculino , Mosquitos Vetores , Plasmodium falciparum/metabolismo , Esfingomielinas/metabolismo
17.
Curr Opin Lipidol ; 33(1): 57-67, 2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-34879042

RESUMO

PURPOSE OF REVIEW: Dementia is a public health challenge with no existing cure or early biomarkers. We review the evidence for blood-based measures of sphingomyelins and ceramides as potential novel biomarkers of dementia. RECENT FINDINGS: In recent years, lipids have been under investigation for their role in neurodegenerative diseases especially dementia and Alzheimer's disease. Increasing evidence from postmortem human brains suggests that alterations in the metabolism of sphingolipids could play a crucial part in dementia. Findings from epidemiological investigations of blood-based sphingomyelins and ceramides have been inconsistent. SUMMARY: This review focuses on blood-based measures of 10 specific ceramides and sphingomyelins (Cer C16:0, Cer C20:0, Cer C22:0, Cer C24:0, Cer C24:1 and SM C16:0, SM C20:0, SM C22:0, SM C24:0, SM C24:1) in relation to cognition and dementia. On the bais of 15 studies, there was no robust association between ceramide and sphingomyelin levels and prevalent or incident dementia. Cross-sectionally, Cer C16:0 and Cer C24:1 tends to be higher in dementia cases vs. controls.


Assuntos
Doença de Alzheimer , Esfingomielinas , Doença de Alzheimer/diagnóstico , Biomarcadores , Encéfalo/metabolismo , Ceramidas/metabolismo , Humanos , Esfingomielinas/metabolismo
18.
J Biol Chem ; 297(6): 101411, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34793834

RESUMO

Cryptococcus neoformans is a fungal pathogen that causes life-threatening meningoencephalitis in lymphopenic patients. Pulmonary macrophages comprise the first line of host defense upon inhalation of fungal spores by aiding in clearance but can also potentially serve as a niche for their dissemination. Given that macrophages play a key role in the outcome of a cryptococcal infection, it is crucial to understand factors that mediate phagocytosis of C. neoformans. Since lipid rafts (high-order plasma membrane domains enriched in cholesterol and sphingomyelin [SM]) have been implicated in facilitating phagocytosis, we evaluated whether these ordered domains govern macrophages' ability to phagocytose C. neoformans. We found that cholesterol or SM depletion resulted in significantly deficient immunoglobulin G (IgG)-mediated phagocytosis of fungus. Moreover, repletion of macrophage cells with a raft-promoting sterol (7-dehydrocholesterol) rescued this phagocytic deficiency, whereas a raft-inhibiting sterol (coprostanol) significantly decreased IgG-mediated phagocytosis of C. neoformans. Using a photoswitchable SM (AzoSM), we observed that the raft-promoting conformation (trans-AzoSM) resulted in efficient phagocytosis, whereas the raft-inhibiting conformation (cis-AzoSM) significantly but reversibly blunted phagocytosis. We observed that the effect on phagocytosis may be facilitated by Fcγ receptor (FcγR) function, whereby IgG immune complexes crosslink to FcγRIII, resulting in tyrosine phosphorylation of FcR γ-subunit (FcRγ), an important accessory protein in the FcγR signaling cascade. Correspondingly, cholesterol or SM depletion resulted in decreased FcRγ phosphorylation. Repletion with 7-dehydrocholesterol restored phosphorylation, whereas repletion with coprostanol showed FcRγ phosphorylation comparable to unstimulated cells. Together, these data suggest that lipid rafts are critical for facilitating FcγRIII-mediated phagocytosis of C. neoformans.


Assuntos
Anticorpos Antifúngicos/metabolismo , Colesterol/metabolismo , Cryptococcus neoformans/metabolismo , Imunoglobulina G/metabolismo , Macrófagos Alveolares/metabolismo , Fagocitose , Receptores de IgG/metabolismo , Esfingomielinas/metabolismo , Animais , Linhagem Celular , Microdomínios da Membrana/metabolismo , Camundongos
19.
Cells ; 10(11)2021 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-34831036

RESUMO

Autophagy is an evolutionarily conserved pathway, in which cytoplasmic components are sequestered within double-membrane vesicles called autophagosomes and then transported into lysosomes or vacuoles for degradation. Over 40 conserved autophagy-related (ATG) genes define the core machinery for the five processes of autophagy: initiation, nucleation, elongation, closure, and fusion. In this review, we focus on one of the least well-characterized events in autophagy, namely the closure of the isolation membrane/phagophore to form the sealed autophagosome. This process is tightly regulated by ESCRT machinery, ATG proteins, Rab GTPase and Rab-related proteins, SNAREs, sphingomyelin, and calcium. We summarize recent progress in the regulation of autophagosome closure and discuss the key questions remaining to be addressed.


Assuntos
Autofagossomos/metabolismo , Animais , Autofagossomos/ultraestrutura , Cálcio/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Humanos , Proteínas SNARE/metabolismo , Esfingomielinas/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo
20.
Cell Rep ; 37(6): 109935, 2021 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-34758297

RESUMO

Sphingomyelin (SM) is a mammalian lipid mainly distributed in the outer leaflet of the plasma membrane (PM). We show that peripheral myelin protein 2 (PMP2), a member of the fatty-acid-binding protein (FABP) family, can localize at the PM and controls the transbilayer distribution of SM. Genetic screening with genome-wide small hairpin RNA libraries identifies PMP2 as a protein involved in the transbilayer movement of SM. A biochemical assay demonstrates that PMP2 is a phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2)-binding protein. PMP2 induces the tubulation of model membranes in a PI(4,5)P2-dependent manner, accompanied by the modification of the transbilayer membrane distribution of lipids. In the PM of PMP2-overexpressing cells, inner-leaflet SM is increased whereas outer-leaflet SM is reduced. PMP2 is a causative protein of Charcot-Marie-Tooth disease (CMT). A mutation in PMP2 associated with CMT increases its affinity for PI(4,5)P2, inducing membrane tubulation and the subsequent transbilayer movement of lipids.


Assuntos
Membrana Celular/metabolismo , Doença de Charcot-Marie-Tooth/metabolismo , Proteína P2 de Mielina/metabolismo , Fosfatidilinositol 4,5-Difosfato/metabolismo , Esfingomielinas/metabolismo , Animais , Transporte Biológico , Membrana Celular/genética , Doença de Charcot-Marie-Tooth/genética , Cães , Células HeLa , Humanos , Células Madin Darby de Rim Canino , Mutação , Proteína P2 de Mielina/genética
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