Biophysics (and sociology) of ceramides.

In the past decade, the long-neglected ceramides (N-acylsphingosines) have become one of the most attractive lipid molecules in molecular cell biology, because of their involvement in essential structures (stratum corneum) and processes (cell signalling). Most natural ceramides have a long (16-24 C atoms) N-acyl chain, but short N-acyl chain ceramides (two to six C atoms) also exist in Nature, apart from being extensively used in experimentation, because they can be dispersed easily in water. Long-chain ceramides are among the most hydrophobic molecules in Nature, they are totally insoluble in water and they hardly mix with phospholipids in membranes, giving rise to ceramide-enriched domains. In situ enzymic generation, or external addition, of long-chain ceramides in membranes has at least three important effects: (i) the lipid monolayer tendency to adopt a negative curvature, e.g. through a transition to an inverted hexagonal structure, is increased, (ii) bilayer permeability to aqueous solutes is notoriously enhanced, and (iii) transbilayer (flip-flop) lipid motion is promoted. Short-chain ceramides mix much better with phospholipids, promote a positive curvature in lipid monolayers, and their capacities to increase bilayer permeability or transbilayer motion are very low or non-existent.

Download Full-text

Integrated lipidomics and proteomics reveal cardiolipin alterations, upregulation of HADHA and long chain fatty acids in pancreatic cancer stem cells

Scientific Reports ◽

10.1038/s41598-021-92752-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Claudia Di Carlo ◽

Bebiana C. Sousa ◽

Marcello Manfredi ◽

Jessica Brandi ◽

Elisa Dalla Pozza ◽

...

Keyword(s):

Pancreatic Cancer ◽

Stem Cells ◽

Fatty Acid ◽

Cancer Stem Cells ◽

Acyl Chain ◽

Fatty Acid Elongase ◽

Acyl Chains ◽

A Chain ◽

Pancreatic Cancer Stem Cells ◽

Long Chain

AbstractPancreatic cancer stem cells (PCSCs) play a key role in the aggressiveness of pancreatic ductal adenocarcinomas (PDAC); however, little is known about their signaling and metabolic pathways. Here we show that PCSCs have specific and common proteome and lipidome modulations. PCSCs displayed downregulation of lactate dehydrogenase A chain, and upregulation of trifunctional enzyme subunit alpha. The upregulated proteins of PCSCs are mainly involved in fatty acid (FA) elongation and biosynthesis of unsaturated FAs. Accordingly, lipidomics reveals an increase in long and very long-chain unsaturated FAs, which are products of fatty acid elongase-5 predicted as a key gene. Moreover, lipidomics showed the induction in PCSCs of molecular species of cardiolipin with mixed incorporation of 16:0, 18:1, and 18:2 acyl chains. Our data indicate a crucial role of FA elongation and alteration in cardiolipin acyl chain composition in PCSCs, representing attractive therapeutic targets in PDAC.

Download Full-text

Long chain sphingomyelin depletes cholesterol from the cytoplasmic leaflet in asymmetric lipid membranes

RSC Advances ◽

10.1039/d1ra01464a ◽

2021 ◽

Vol 11 (37) ◽

pp. 22677-22682

Author(s):

Maria Lyngby Karlsen ◽

Dennis S. Bruhn ◽

Weria Pezeshkian ◽

Himanshu Khandelia

Keyword(s):

Outer Membrane ◽

Lipid Membranes ◽

Acyl Chain ◽

Outer Membrane Leaflet ◽

Long Chain

Long acyl chain sphingomyelin and saturated phospholipid tails in the outer membrane leaflet deplete cholesterol from the inner leaflet in mammalian membranes.

Download Full-text

Photoluminescence Enhancement of CdS Nanocrystals Fabricated on Dithiocarbamate Functionalized PET Substrates

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.512-515.1511 ◽

2012 ◽

Vol 512-515 ◽

pp. 1511-1515

Author(s):

Chun Lin Zhao ◽

Li Xing ◽

Xiao Hong Liang ◽

Jun Hui Xiang ◽

Fu Shi Zhang ◽

...

Keyword(s):

Room Temperature ◽

Hexagonal Structure ◽

Diffraction Measurement ◽

X Ray Diffraction ◽

Visible Absorption ◽

X Ray ◽

Cds Nanocrystals ◽

Morphological Studies ◽

Transmission Electron

Cadmium sulfide (CdS) nanocrystals (NCs) were self-assembled and in-situ immobilized on the dithiocarbamate (DTCs)-functionalized polyethylene glycol terephthalate (PET) substrates between the organic (carbon disulfide diffused in n-hexane) –aqueous (ethylenediamine and Cd2+ dissolved in water) interface at room temperature. Powder X-ray diffraction measurement revealed the hexagonal structure of CdS nanocrystals. Morphological studies performed by scanning electron microscopy (SEM) and high-resolution transmission electron microscope (HRTEM) showed the island-like structure of CdS nanocrystals on PET substrates, as well as energy-dispersive X-ray spectroscopy (EDS) confirmed the stoichiometries of CdS nanocrystals. The optical properties of DTCs modified CdS nanocrystals were thoroughly investigated by ultraviolet-visible absorption spectroscopy (UV-vis) and fluorescence spectroscopy. The as-prepared DTCs present intrinsic hydrophobicity and strong affinity for CdS nanocrystals.

Download Full-text

Bridging scales: From cell biology to physiology using in situ single-cell technologies

Cell Systems ◽

10.1016/j.cels.2021.03.002 ◽

2021 ◽

Vol 12 (5) ◽

pp. 388-400

Author(s):

Maeve P. Nagle ◽

Gabriela S. Tam ◽

Evan Maltz ◽

Zachary Hemminger ◽

Roy Wollman

Keyword(s):

Single Cell ◽

Cell Biology ◽

Cell Technologies

Download Full-text

Structural Insight Into Aeromonas Hydrophila AHL Synthase AhyI Driving Acyl-ACP Selective Recognition

10.21203/rs.3.rs-403119/v1 ◽

2021 ◽

Author(s):

Lei Jin ◽

Yu chen ◽

Wenge Yang

Keyword(s):

Aeromonas Hydrophila ◽

Acyl Chain ◽

Virulence Gene ◽

Kinetic Studies ◽

Homoserine Lactone ◽

Selective Recognition ◽

Acyl Donor ◽

Virulence Gene Expression ◽

Long Chain

Abstract Background: The gram-negative bacterium Aeromonas hydrophila as the major causative agent of the fish disease motile aeromonad septicemia, uses N-acyl-homoserine lactone quorum sensing signals to coordinate biofilm formation, motility and virulence gene expression in pathogens. Thus, AHL signaling pathway is considered as a therapeutic target against pathogenic A. hydrophila infection. AHL autoinducers biosynthesis in A. hydrophila are specifically catalyzed by an ACP-dependent AHL synthase AhyI using SAM and acyl-ACP as the precursors. Our previously reported AhyI protein heterologously expressed in E. coli strain showed the production characteristics of medium-long chain AHLs, although AhyI was only considered as a short-chain C4/C6-HSL synthase during the past two decades.Results: In this study, we carried out the in vitro biosynthetic assays of six AHL molecules and kinetic studies of recombinant AhyI with a panel of four linear acyl-ACPs. These resulting data all indicate that C4/C6-ACP are the native acyl substrates for AhyI against acyl-ACPs with longer linear chains as the non-native acyl donor. In an effort to further understand AhyI acyl-donor substrates preferences, we performed a structural comparison of three ACP-dependent LuxI homologs (TofI, BmaI1 and AhyI), and identified three key hydrophobic residues (I67, F125 and L157) as part of the acyl-chain binding pocket that confer AhyI to selectively recognize native C4/C6-ACP substrates. The predictions were further supported by computational Ala mutation assay.Conclusions: Our current studies redefined AhyI protein that is a multiple short- to long-chain AHL molecules synthase with longer acyl-ACPs (C8~C14) as the non-native substrates, and we also theorized that with knowledge of the key residues in AHL signal synthase AhyI to drive acyl-ACP selective recognition.

Download Full-text

The ciliary protein IFT88 controls post-natal cartilage thickness and influences development of osteoarthritis

10.1101/2020.07.29.225599 ◽

2020 ◽

Author(s):

CR Coveney ◽

L Zhu ◽

J Miotla-Zarebska ◽

B Stott ◽

I Parisi ◽

...

Keyword(s):

Articular Cartilage ◽

Cell Biology ◽

Articular Chondrocytes ◽

Skeletal Development ◽

Cartilage Degradation ◽

Cartilage Thickness ◽

Tissue Growth ◽

Calcified Cartilage ◽

Health And Disease

AbstractMechanical forces are known to drive cellular signalling programmes in cartilage development, health, and disease. Proteins of the primary cilium, implicated in mechanoregulation, control cartilage formation during skeletal development, but their role in post-natal cartilage is unknown. Ift88fl/fl and AggrecanCreERT2 mice were crossed to create a cartilage specific inducible knockout mouse AggrecanCreERT2;Ift88fl/fl. Tibial articular cartilage thickness was assessed, through adolescence and adulthood, by histomorphometry and integrity by OARSI score. In situ cell biology was investigated by immunohistochemistry (IHC) and qPCR of micro-dissected cartilage. OA was induced by destabilisation of the medial meniscus (DMM). Some mice were provided with exercise wheels in their cage. Deletion of IFT88 resulted in a reduction in medial articular cartilage thickness (atrophy) during adolescence from 102.57μm, 95% CI [94.30, 119.80] in control (Ift88fl/fl) to 87.36μm 95% CI [81.35, 90.97] in AggrecanCreERT2;Ift88fl/fl by 8-weeks p<0.01, and adulthood (104.00μm, 95% CI [100.30, 110.50] in Ift88fl/fl to 89.42μm 95% CI [84.00, 93.49] in AggrecanCreERT2;Ift88fl/fl, 34-weeks, p<0.0001) through a reduction in calcified cartilage. Thinning in adulthood was associated with spontaneous cartilage degradation. Following DMM, AggrecanCreERT2;Ift88fl/fl mice had increased OA (OARSI scores at 12 weeks Ift88fl/fl = 22.08 +/− 9.30, and AggrecanCreERT2;Ift88fl/fl = 29.83 +/− 7.69). Atrophy was not associated with aggrecanase-mediated destruction or chondrocyte hypertrophy. Ift88 expression positively correlated with Tcf7l2 and connective tissue growth factor. Cartilage thickness was restored in AggrecanCreERT2;Ift88fl/fl by voluntary wheel exercise. Our results demonstrate that ciliary IFT88 regulates cartilage thickness and is chondroprotective, potentially through modulating mechanotransduction pathways in articular chondrocytes.

Download Full-text

Effect of different long-chain fatty acids on cholecystokinin releasein vitroand energy intake in free-living healthy males

British Journal Of Nutrition ◽

10.1017/s0007114511006003 ◽

2012 ◽

Vol 108 (4) ◽

pp. 755-758 ◽

Cited By ~ 12

Author(s):

Charlotte J. Harden ◽

Adam N. Jones ◽

Tannia Maya-Jimenez ◽

Margo E. Barker ◽

Natalie J. Hepburn ◽

...

Keyword(s):

Fatty Acids ◽

Chain Length ◽

Energy Intake ◽

Acyl Chain ◽

Dependent Manner ◽

Long Chain Fatty Acids ◽

Long Chain ◽

Healthy Males ◽

Cck Release ◽

Chain Fatty Acids

Long-chain fatty acids have been shown to suppress appetite and reduce energy intake (EI) by stimulating the release of gastrointestinal hormones such as cholecystokinin (CCK). The effect of NEFA acyl chain length on these parameters is not comprehensively understood. Anin vitroscreen tested the capacity of individual NEFA (C12 to C22) to trigger CCK release. There was a gradient in CCK release with increasing chain length. DHA (C22) stimulated significantly (P < 0·01) more CCK release than all other NEFA tested. Subsequently, we conducted a randomised, controlled, crossover intervention study using healthy males (n18). The effects of no treatment (NT) and oral doses of emulsified DHA-rich (DHA) and oleic acid (OA)-rich oils were compared using 24 h EI as the primary endpoint. Participants reported significantly (P = 0·039) lower total daily EI (29 % reduction) with DHA compared to NT. There were no differences between DHA compared to OA and OA compared to NT. There was no between-treatment difference in the time to, or EI of, the first post-intervention eating occasion. It is concluded that NEFA stimulate CCK release in a chain length-dependent manner up to C22. These effects may be extended to thein vivosetting, as a DHA-based emulsion significantly reduced short-term EI.

Download Full-text

In situ ozonolysis of polypropylene during extrusion to produce long-chain branches with the aid of TMPTA

RSC Advances ◽

10.1039/c7ra03121a ◽

2017 ◽

Vol 7 (36) ◽

pp. 22531-22539 ◽

Cited By ~ 4

Author(s):

Guang-Jian He ◽

Bing-Yu Yuan ◽

Ting-Ting Zheng ◽

Wen-li Zhu ◽

Xiao-Chun Yin

Keyword(s):

Extrusion Process ◽

Secondary Products ◽

Long Chain

The introduction of long-chain branches (LCBs) in polypropylene (PP) during the extrusion process is normally induced by peroxide chemicals which are known to cause to the formation of secondary products in the resin.

Download Full-text

Abstract 16607: Age-induced Endoplasmic Reticulum Stress in the Heart: Role of Increased Very Long-chain Ceramides

Circulation ◽

10.1161/circ.142.suppl_3.16607 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Qun Chen ◽

Anna Kovilakath ◽

Jeremy Allegood ◽

Lauren A Cowart ◽

Edward J Lesnefsky

Keyword(s):

Er Stress ◽

Mitochondrial Dysfunction ◽

Acyl Chain ◽

Membrane Domains ◽

Ceramide Synthase ◽

Age Related ◽

Chain Lengths ◽

Endoplasm Reticulum ◽

Long Chain

Introduction: Mitochondrial function is impaired in aged hearts. Increased endoplasm reticulum (ER) stress contributes to the mitochondrial dysfunction observed during aging. Ceramides (CRMD) are sphingolipid metabolites that contribute key roles in cell signaling. Increased CRMD can lead to ER stress. Ceramide synthase enzymes (CerS) generate chain length specific CRMD with the CerS isoform 2 (Cers2) forming very long chain CRMD of ≥ 20 carbon acyl chain lengths. Hypothesis: An increase in CRMD content during aging contributes to age-related ER stress. Methods: Male mice (3, 18, 24 mo.) from the NIA colony were studied. Cardiac mitochondria (MITO), mitochondrial associated membranes (MAM), and ER were isolated from mouse hearts. CRMD content was measured using LC-MS. The contents of CerS enzymes were measured by immunoblotting in myocardial homogenates. Results: ER stress increased progressively during aging with increased contents of cleaved ATF6 and CHOP, indicators of increased ER stress, evident at 18 and 24 mo. (Panel A) (all data mean±SEM; *p<0.05 vs. 3 mo., † p<0.05 vs. 18 mo.). Aging increased very long-chain CRMD (≥C20) in ER (Panel B) at 18 and 24 mo. Similar CRMD trends were observed MAM (Panel C), shared membrane domains where ER and MITO interact. The content of CerS2 was increased at 24 mo. compared to 3 mo. (Panel D, n=4 each age). In contrast, the contents of CerS isoforms 4 and 5, that generate shorter chain CRMD (<C20) were unchanged (not shown). CRMD contents in MITO were unaltered with age (not shown). Thus, increased generation of very long chain CRMD in the ER is the likely mechanism of increased ER stress in the aged heart. Conclusion: Aging increased ER CRMD content by enhancing the formation of very long chain CRMD in ER by an increase in CerS2 content, concomitant with the onset of ER stress. The increase in age-induced ER stress, in turn, leads to mitochondrial dysfunction in the aged heart.

Download Full-text

Electro-Optical Probing for Capturing Fast-to-Rise Scan Chain Failures

10.31399/asm.cp.istfa2021p0366 ◽

2021 ◽

Author(s):

Karl Villareal ◽

Rommel Estores ◽

Peter Baert

Keyword(s):

Fault Isolation ◽

Flip Flop ◽

Diagnosis System ◽

Chain Analysis ◽

System 2 ◽

Optical Probing ◽

Scan Chain ◽

Imaging Sensor ◽

Chain Links ◽

Long Chain

Abstract The paper discusses an imaging sensor exhibiting a fast-to-rise sanity check failure from a scan chain test. The DUT was prepared for backside analysis in a portable daughter-card [1] that enabled the analyst to easily shift between testing platforms such as a standard imaging tester bench and compact scan diagnosis system [2], while being inspected under the Electro-Optical Probing (EOP) machine. To find a failing flip-flop in several-thousands long chain, broken scan chain analysis was performed to narrow down the search to a few chain links was implemented. EOP methods of fault isolation were employed to verify the location of the broken scan cell in those selected flip-flops. Finally, parallel lapping was done to confirm the location of the failing flip-flop under a SEM.

Download Full-text