CLN3 loss disturbs membrane microdomain properties and protein transport in brain endothelial cells

Juvenile neuronal ceroid lipofuscinosis (JNCL) is a fatal childhood-onset neurodegenerative disorder caused by mutations in ceroid lipofuscinosis neuronal-3 (CLN3), a hydrophobic transmembrane protein of unresolved function. Previous studies indicate blood–brain barrier (BBB) defects in JNCL, and our earlier report showed prominent Cln3 expression in mouse brain endothelium. Here we find that CLN3 is necessary for normal trafficking of the microdomain-associated proteins caveolin-1, syntaxin-6, and multidrug resistance protein 1 (MDR1) in brain endothelial cells. Correspondingly, CLN3-null cells have reduced caveolae, and impaired caveolae- and MDR1-related functions including endocytosis, drug efflux, and cell volume regulation. We also detected an abnormal blood–brain barrier response to osmotic stress in vivo. Evaluation of the plasma membrane with fluorescent sphingolipid probes suggests

Induction of a hardening phenomenon by repeated application of SLS: analysis of lipid changes in the stratum corneum

Adaptation of the skin to repeated influence of exogenous irritants is called the hardening phenomenon. We investigated the stratum corneum lipid composition before and after induction of a hardening phenomenon. Irritant contact dermatitis was induced in 23 non-atopic volunteers by repeated occlusive application of 0.5% sodium lauryl sulfate (SLS) over 3 weeks. At 3, 6 and 9 weeks after irritation, the SLS responses of pre-irritated skin and normal skin were compared. The horny layer lipid composition (ceramides 1–7, cholesterol and free fatty acids) was assessed before irritation and 3, 6 and 9 weeks after irritation. During the first 2 weeks of irritation the transepidermal water loss increased continuously and seemed to decrease during the third week (effect of adaptation). The barrier function of pre-irritated sites was more stable to SLS challenge. Three weeks after irritation, there was a significant increase of ceramide 1 (pv0. 001). The only volunteer without hardening phenomenon showed no increase of ceramide 1. Ceramide 1 seems to play a key role as a protection mechanism against repeated irritation. Key words: hardening phenomenon; irritant contact dermatitis; stratum corneum lipids; ceramides; transepidermal water loss

Water permeation through stratum corneum lipid bilayers from atomistic simulations

Stratum corneum, the outermost layer of skin, consists of keratin filled rigid non-viable corneocyte cells surrounded by multilayers of lipids. The lipid layer is responsible for the barrier properties of the skin. We calculate the excess chemical potential and diffusivity of water as a function of depth in lipid bilayers with compositions representative of the stratum corneum using atomistic molecular dynamics simulations. The maximum in the excess free energy of water inside the lipid bilayers is found to be twice that of water in phospholipid bilayers at the same temperature. Permeability, which decreases exponentially with the free energy barrier, is reduced by several orders of magnitude as compared to with phospholipid bilayers. The average time it takes for a water molecule to cross the bilayer is calculated by solving the Smoluchowski equation in presence of the free energy barrier. For a bilayer composed of a 2:2:1 molar ratio of ceramide NS 24:0, cholesterol and free fatty acid 24:0 at 300K, we estimate the permeability P=3.7e-9 cm/s and the average crossing time \tau_{av}=0.69 ms. The permeability is about 30 times smaller than existing experimental results on mammalian skin sections.Comment: latex, 8 pages, 6 figure

Stratum corneum lipid matrix with unusual packing: a molecular dynamics study

The skin is an effective barrier against the external elements being the stratum corneum, with its lipid matrix surrounding the corneocytes, considered the major player responsible for its low permeability. The use of computational models to study the transdermal delivery of compounds have a huge potential to improve this research area, but requires reliable models of the skin components. In this work, we developed molecular dynamics models with a coarse-grained resolution, of the stratum corneum lipid matrix and the sebum. We developed the lipid matrix model with unusual lipid packing configuration as some recent works support. The simulation results show that this configuration is stable and may help to explain the low permeability of stratum corneum. The sebum simulations showed that this oily skin product can also play a significant role in the transdermal delivery of drugs.We thank the Portuguese Foundation for Science and Technology (FCT) for providing the grant for part of Egipto Antunes Ph.D. studies (scholarship SFRH/BD/122952/2016), and to also support this work under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. We want to thank the access of Minho University “SeARCH” ("Services and Advanced Research Computing with HTC/HPC clusters") cluster. We also thank Tarsila Castro for its technical advice and text revision.info:eu-repo/semantics/publishedVersio

Assessment of penetration of Ascorbyl Tetraisopalmitate into biological membranes by molecular dynamics

The present work, involves the simulation of the transport of a vitamin C derivative, Ascorbyl Tetraisopalmitate (ATI), through human skin by molecular dynamics. Percutaneous absorption of the ATI molecule through the infundibulum, an important route of absorption into the hair follicle of the human skin, has been modeled and compared with the stratum corneum membrane. The comparative study was done, using molecular dynamics with Martini force field. In infundibulum, a single ATI molecule require more time to penetrate, and the data obtained suggested that a high concentration of ATI molecule accelerated the process of penetration. In conclusion, the ATI molecule was found to have more affinity towards the stratum corneum as compared towards the infundibulum and it followed a straight pathway to penetrate (until 600 ns of simulation). In infundibulum, it showed less affinity, more mobility and followed a lateral pathway. Thus, this work contributes to a better understanding of the different molecular interactions during percutaneous absorption of active molecules in these two different types of biological membranes.The authors acknowledge financial support from the Brazilian agencies CAPES, Finep and Fapesp (Project FINEP 01.10.0661-00, FAPESP 2011/13250-0, FAPESP 2013/17247-9, FAPESP 2014/05975-2, CAPES 88887068264/2014-00), of Institute of Research and Development, University of Vale Paraíba

An Introduction to Sphingolipid Metabolism and Analysis by New Technologies

Sphingolipids (SP) are a complex class of molecules found in essentially all eukaryotes and some prokaryotes and viruses where they influence membrane structure, intracellular signaling, and interactions with the extracellular environment. Because of the combinatorial nature of their biosynthesis, there are thousands of SP subspecies varying in the lipid backbones and complex phospho- and glycoheadgroups. Therefore, comprehensive or “sphingolipidomic” analyses (structure-specific, quantitative analyses of all SP, or at least all members of a critical subset) are needed to know which and how much of these subspecies are present in a system as a step toward understanding their functions. Mass spectrometry and related novel techniques are able to quantify a small fraction, but nonetheless a substantial number, of SP and are beginning to provide information about their localization. This review summarizes the basic metabolism of SP and state-of-art mass spectrometric techniques that are producing insights into SP structure, metabolism, functions, and some of the dysfunctions of relevance to neuromedicine

Untersuchung der Ceramide des Stratum corneum in der nicht involvierten Haut bei Neurodermitis-und Psoriasis-Patienten mit Hilfe der AMD-HPTLC und der HPLC

Lipide stellen bedeutende Naturstoffe dar, die in jedem Organismus vorkommen und vielfältige Funktionen erfüllen. Sie rücken auf Grund dessen vermehrt in den Mittelpunkt der heutigen Forschung. In diesem Zusammenhang sind die weltweit entstehenden großen Lipidomics-Projekte zu erwähnen, deren Bedeutung darin liegt, die Lipide zu charakterisieren, deren Rollen besser zu erfassen und daraus zu ergründen, inwiefern neue therapeutische Einsatzmöglichkeiten bestehen. Ceramide gehören zu der Gruppe der Sphingolipide und sind hauptsächlich dafür bekannt, dass sie der Signaltransduktion dienen und die „Apoptose “, den programmierten Zelltod, vermitteln. Im Stratum corneum (SC), der äußersten Schicht der menschlichen Haut, sind sie hingegen unerlässlich für die Aufrechterhaltung des Lebens. Sie tragen dort maßgeblich zum Schutz des Körpers vor äußeren Schädigungen und zur Verhinderung von unkontrolliertem Wasserverlust bei. Die SC-Ceramide zeichnen sich durch ihre komplexe, einzigartige und nicht in anderen Körpergeweben anzutreffende Zusammensetzung aus, die auf vielfältigen Strukturelementen und deren Kombinationen beruht. Dadurch wird deren Analytik zu einer herausfordernden Aufgabe. Als Methode der ersten Wahl zur Untersuchung der SC-Lipide und damit auch der SC-Ceramide hat sich die klassische Dünnschichtchromatographie etabliert, was auf deren Robustheit und die idR nicht erforderliche Abtrennung unerwünschter Bestandteile zurückzuführen ist. Nachteilig sind allerdings die manuellen arbeitsintensiven Trennprozeduren sowie die auf Grund lateraler Diffusion breiten und schlecht zu

Lipidomics

Lipids are hydrophobic or amphiphilic low‐molecular‐weight substances with a low solubility in water. Glycerophospholipids, sphingolipids, and cholesterol are the building blocks of cellular membranes, and triacylglycerols are the major molecular storage forms of metabolic energy. Various lipids serve as signaling substances either as first or second messengers in signal transduction; as autocrinic, paracrinic, or endocrinic regulators; or are covalently bound to cellular proteins. Several diseases are caused by, or at least associated with, alterations in lipid metabolism, such as inherited disorders of lipid metabolism, atherosclerosis, diabetes, obesity, or Alzheimer's disease

Lipidomics of glycosphingolipids

: Glycosphingolipids (GSLs) contain one or more sugars that are attached to a sphingolipid moiety, usually to a ceramide, but in rare cases also to a sphingoid base. A large structural heterogeneity results from differences in number, identity, linkage, and anomeric configuration of the carbohydrate residues, and also from structural differences within the hydrophobic part. GSLs form complex cell-type specific patterns, which change with the species, the cellular differentiation state, viral transformation, ontogenesis, and oncogenesis. Although GSL structures can be assigned to only a few series with a common carbohydrate core, their structural variety and the complex pattern are challenges for their elucidation and quantification by mass spectrometric techniques. We present a general overview of the application of lipidomics for GSL determination. This includes analytical procedures and instrumentation together with recent correlations of GSL molecular species with human diseases. Difficulties such as the structural complexity and the lack of standard substances for complex GSLs are discussed