Effects of Lipid Chain Lengths in α-Galactosylceramides on Cytokine Release by Natural Killer T Cells
摘要:
Glycolipid presentation by CD1 proteins has emerged as an important aspect of antigen recognition, and presentation of alpha-glycosylceramides by CD1d to natural killer T cells has become a central focus in understanding how glycolipid presentation can influence immune responses. An alpha-galactosylceramide containing relatively long lipid chains has been the subject of intense study because, when presented by CD1d to natural killer T cells, it stimulates the release of both proinflammatory and immunomodulatory cytokines. Using an efficient synthesis of alpha-galactosylceramides, we have prepared a series of glycolipids in which the lipid chain lengths have been incrementally varied. The responses of natural killer T cells to these glycolipids have been determined, and we have found that truncation of the phytosphingosine lipid chain increases the relative amounts of immunomodulatory cytokines released. In similar fashion, the length of the acyl chain in alpha-galactosylceramides influences cytokine release profiles.
Convergent evolution of bacterial ceramide synthesis
作者:Gabriele Stankeviciute、Peijun Tang、Ben Ashley、Joshua D. Chamberlain、Matthew E. B. Hansen、Aimiyah Coleman、Rachel D’Emilia、Larina Fu、Eric C. Mohan、Hung Nguyen、Ziqiang Guan、Dominic J. Campopiano、Eric A. Klein
DOI:10.1038/s41589-021-00948-7
日期:2022.3
The bacterial domain produces numerous types of sphingolipids with various physiological functions. In the human microbiome, commensal and pathogenic bacteria use these lipids to modulate the host inflammatory system. Despite their growing importance, their biosynthetic pathway remains undefined since several key eukaryotic ceramide synthesis enzymes have no bacterial homolog. Here we used genomic and biochemical approaches to identify six proteins comprising the complete pathway for bacterial ceramide synthesis. Bioinformatic analyses revealed the widespread potential for bacterial ceramide synthesis leading to our discovery of a Gram-positive species that produces ceramides. Biochemical evidence demonstrated that the bacterial pathway operates in a different order from that in eukaryotes. Furthermore, phylogenetic analyses support the hypothesis that the bacterial and eukaryotic ceramide pathways evolved independently. Elucidation of the bacterial ceramide biosynthetic pathway reveals that it likely evolved independently from the eukaryotic pathway, as bacteria lack homologs for many of the eukaryotic enzymes and the reactions occur in a different order.
In spite of numerous synthetic routes to ceramide analogs, relatively few reports of the direct coupling of the unprotected phytosphingosine with the activated palmitic acid via amide bond formation are available. After purification by HPLC, the chromatogram indicated some impurities had not been removed during previous column chromatography. With the pure ceramides in hand, derivatization with the
The present invention provides an efficient method for the production of N-acyl amino alcohols via the selective acylation of the free amines of amino alcohols by reacting with an organic acid or a salt thereof with an alkyl sulfonyl chloride or an alkyl phenyl sulfonyl chloride, in an organic solvent and in the presence of an organic base, to form the corresponding mixed anhydride, followed by reacting the mixed anhydride with an amino alcohol or a salt thereof to form the corresponding N-acyl amino alcohol.
metabolized to ceramides and SPD 1‐phosphate with almost the same efficiency as sphingosine, it is less susceptible to degradation by a cleavage reaction, at least in vitro. We identified the fatty acid desaturase family protein FADS3 as a ceramide desaturase that produces SPD ceramides by desaturating ceramides containing sphingosine. SPD sphingolipids were preferentially localized outside lipid microdomains
鞘脂是多功能脂质。在鞘脂组分鞘氨醇碱基中,4,14-鞘氨醇 (SPD) 是独一无二的,它具有一个弯曲结构的顺式双键。尽管半个世纪前就发现了 SPD,但其组织分布、生物合成和降解仍知之甚少。在这里,我们建立了一种特异性和定量的 SPD 测量方法,发现 SPD 存在于广泛的哺乳动物组织中。SPD 在肾脏中特别丰富,其中 SPD 的量约为鞘氨醇的 2/3,鞘氨醇是哺乳动物中最丰富的鞘氨醇碱。尽管 SPD 代谢为神经酰胺和 SPD 1-磷酸酯的效率几乎与鞘氨醇相同,但它不太容易被裂解反应降解,至少在体外是这样。我们将脂肪酸去饱和酶家族蛋白 FADS3 鉴定为一种神经酰胺去饱和酶,它通过使含有鞘氨醇的神经酰胺去饱和来产生 SPD 神经酰胺。SPD 鞘脂优先定位于脂质微域之外,这表明 SPD 在脂质微域形成方面与其他鞘氨醇碱基相比具有不同的功能。总之,我们揭示了 SPD 的生物合成和降解途径及其特征性
Substrate specificity, kinetic properties and inhibition by fumonisin B1 of ceramide synthase isoforms from Arabidopsis
作者:Kyle D. Luttgeharm、Edgar B. Cahoon、Jonathan E. Markham
DOI:10.1042/bj20150824
日期:2016.3.1
Ceramides are organizing components of sphingolipids in the eukaryotic cell. Three ceramide synthase isoforms are found in Arabidopsis thaliana each with specific substrate preferences and sensitivity to inhibitors and activators.