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German A, Jukic J, Laner A, Arnold P, Socher E, Mennecke A, Schmidt MA, Winkler J, Abicht A, Regensburger M. Novel Homozygous FA2H Variant Causing the Full Spectrum of Fatty Acid Hydroxylase-Associated Neurodegeneration (SPG35). Genes (Basel) 2023; 15:14. [PMID: 38275596 PMCID: PMC10815826 DOI: 10.3390/genes15010014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 12/15/2023] [Accepted: 12/16/2023] [Indexed: 01/27/2024] Open
Abstract
Fatty acid hydroxylase-associated neurodegeneration (FAHN/SPG35) is caused by pathogenic variants in FA2H and has been linked to a continuum of specific motor and non-motor neurological symptoms, leading to progressive disability. As an ultra-rare disease, its mutational spectrum has not been fully elucidated. Here, we present the prototypical workup of a novel FA2H variant, including clinical and in silico validation. An 18-year-old male patient presented with a history of childhood-onset progressive cognitive impairment, as well as progressive gait disturbance and lower extremity muscle cramps from the age of 15. Additional symptoms included exotropia, dystonia, and limb ataxia. Trio exome sequencing revealed a novel homozygous c.75C>G (p.Cys25Trp) missense variant in the FA2H gene, which was located in the cytochrome b5 heme-binding domain. Evolutionary conservation, prediction models, and structural protein modeling indicated a pathogenic loss of function. Brain imaging showed characteristic features, thus fulfilling the complete multisystem neurodegenerative phenotype of FAHN/SPG35. In summary, we here present a novel FA2H variant and provide prototypical clinical findings and structural analyses underpinning its pathogenicity.
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Affiliation(s)
- Alexander German
- Department of Molecular Neurology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Jelena Jukic
- Department of Molecular Neurology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Andreas Laner
- MGZ—Medizinisch Genetisches Zentrum, 80335 Munich, Germany
| | - Philipp Arnold
- Institute of Functional and Clinical Anatomy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Eileen Socher
- Institute of Functional and Clinical Anatomy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Angelika Mennecke
- Institute of Neuroradiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Manuel A. Schmidt
- Institute of Neuroradiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Jürgen Winkler
- Department of Molecular Neurology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
- Center for Rare Diseases (ZSEER), University Hospital Erlangen, 91054 Erlangen, Germany
| | - Angela Abicht
- MGZ—Medizinisch Genetisches Zentrum, 80335 Munich, Germany
| | - Martin Regensburger
- Department of Molecular Neurology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
- Center for Rare Diseases (ZSEER), University Hospital Erlangen, 91054 Erlangen, Germany
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Fatty Acid 2-Hydroxylase and 2-Hydroxylated Sphingolipids: Metabolism and Function in Health and Diseases. Int J Mol Sci 2023; 24:ijms24054908. [PMID: 36902339 PMCID: PMC10002949 DOI: 10.3390/ijms24054908] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 02/28/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023] Open
Abstract
Sphingolipids containing acyl residues that are hydroxylated at C-2 are found in most, if not all, eukaryotes and certain bacteria. 2-hydroxylated sphingolipids are present in many organs and cell types, though they are especially abundant in myelin and skin. The enzyme fatty acid 2-hydroxylase (FA2H) is involved in the synthesis of many but not all 2-hydroxylated sphingolipids. Deficiency in FA2H causes a neurodegenerative disease known as hereditary spastic paraplegia 35 (HSP35/SPG35) or fatty acid hydroxylase-associated neurodegeneration (FAHN). FA2H likely also plays a role in other diseases. A low expression level of FA2H correlates with a poor prognosis in many cancers. This review presents an updated overview of the metabolism and function of 2-hydroxylated sphingolipids and the FA2H enzyme under physiological conditions and in diseases.
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Ukawa T, Banno F, Ishikawa T, Kasahara K, Nishina Y, Inoue R, Tsujii K, Yamaguchi M, Takahashi T, Fukao Y, Kawai-Yamada M, Nagano M. Sphingolipids with 2-hydroxy fatty acids aid in plasma membrane nanodomain organization and oxidative burst. PLANT PHYSIOLOGY 2022; 189:839-857. [PMID: 35312013 PMCID: PMC9157162 DOI: 10.1093/plphys/kiac134] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 02/28/2022] [Indexed: 05/21/2023]
Abstract
Plant sphingolipids mostly possess 2-hydroxy fatty acids (HFA), the synthesis of which is catalyzed by FA 2-hydroxylases (FAHs). In Arabidopsis (Arabidopsis thaliana), two FAHs (FAH1 and FAH2) have been identified. However, the functions of FAHs and sphingolipids with HFAs (2-hydroxy sphingolipids) are still unknown because of the lack of Arabidopsis lines with the complete deletion of FAH1. In this study, we generated a FAH1 mutant (fah1c) using CRISPR/Cas9-based genome editing. Sphingolipid analysis of fah1c, fah2, and fah1cfah2 mutants revealed that FAH1 hydroxylates very long-chain FAs (VLCFAs), whereas the substrates of FAH2 are VLCFAs and palmitic acid. However, 2-hydroxy sphingolipids are not completely lost in the fah1cfah2 double mutant, suggesting the existence of other enzymes catalyzing the hydroxylation of sphingolipid FAs. Plasma membrane (PM) analysis and molecular dynamics simulations revealed that hydroxyl groups of sphingolipid acyl chains play a crucial role in the organization of nanodomains, which are nanoscale liquid-ordered domains mainly formed by sphingolipids and sterols in the PM, through hydrogen bonds. In the PM of the fah1cfah2 mutant, the expression levels of 26.7% of the proteins, including defense-related proteins such as the pattern recognition receptors (PRRs) brassinosteroid insensitive 1-associated receptor kinase 1 and chitin elicitor receptor kinase 1, NADPH oxidase respiratory burst oxidase homolog D (RBOHD), and heterotrimeric G proteins, were lower than that in the wild-type. In addition, reactive oxygen species (ROS) burst was suppressed in the fah1cfah2 mutant after treatment with the pathogen-associated molecular patterns flg22 and chitin. These results indicated that 2-hydroxy sphingolipids are necessary for the organization of PM nanodomains and ROS burst through RBOHD and PRRs during pattern-triggered immunity.
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Affiliation(s)
- Tomomi Ukawa
- Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama 338-8570, Japan
| | - Fumihiko Banno
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Toshiki Ishikawa
- Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama 338-8570, Japan
| | - Kota Kasahara
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Yuuta Nishina
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Rika Inoue
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Keigo Tsujii
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Masatoshi Yamaguchi
- Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama 338-8570, Japan
| | - Takuya Takahashi
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Yoichiro Fukao
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Maki Kawai-Yamada
- Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama 338-8570, Japan
| | - Minoru Nagano
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
- Author for correspondence:
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Gunay A, Shin HH, Gozutok O, Gautam M, Ozdinler PH. Importance of lipids for upper motor neuron health and disease. Semin Cell Dev Biol 2020; 112:92-104. [PMID: 33323321 DOI: 10.1016/j.semcdb.2020.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 10/12/2020] [Accepted: 11/11/2020] [Indexed: 12/18/2022]
Abstract
Building evidence reveals the importance of maintaining lipid homeostasis for the health and function of neurons, and upper motor neurons (UMNs) are no exception. UMNs are critically important for the initiation and modulation of voluntary movement as they are responsible for conveying cerebral cortex' input to spinal cord targets. To maintain their unique cytoarchitecture with a prominent apical dendrite and a very long axon, UMNs require a stable cell membrane, a lipid bilayer. Lipids can act as building blocks for many biomolecules, and they also contribute to the production of energy. Therefore, UMNs require sustained control over the production, utilization and homeostasis of lipids. Perturbations of lipid homeostasis lead to UMN vulnerability and progressive degeneration in diseases such as hereditary spastic paraplegia (HSP) and primary lateral sclerosis (PLS). Here, we discuss the importance of lipids, especially for UMNs.
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Affiliation(s)
- Aksu Gunay
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA, 60611
| | - Heather H Shin
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA, 60611
| | - Oge Gozutok
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA, 60611
| | - Mukesh Gautam
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA, 60611
| | - P Hande Ozdinler
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA, 60611.
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Hardt R, Jordans S, Winter D, Gieselmann V, Wang-Eckhardt L, Eckhardt M. Decreased turnover of the CNS myelin protein Opalin in a mouse model of hereditary spastic paraplegia 35. Hum Mol Genet 2020; 29:3616-3630. [PMID: 33215680 DOI: 10.1093/hmg/ddaa246] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/09/2020] [Accepted: 11/10/2020] [Indexed: 02/07/2023] Open
Abstract
Spastic paraplegia 35 (SPG35) (OMIM: 612319) or fatty acid hydroxylase-associated neurodegeneration (FAHN) is caused by deficiency of fatty acid 2-hydroxylase (FA2H). This enzyme synthesizes sphingolipids containing 2-hydroxylated fatty acids, which are particularly abundant in myelin. Fa2h-deficient (Fa2h-/-) mice develop symptoms reminiscent of the human disease and therefore serve as animal model of SPG35. In order to understand further the pathogenesis of SPG35, we compared the proteome of purified CNS myelin isolated from wild type and Fa2h-/- mice at different time points of disease progression using tandem mass tag labeling. Data analysis with a focus on myelin membrane proteins revealed a significant increase of the oligodendrocytic myelin paranodal and inner loop protein (Opalin) in Fa2h-/- mice, whereas the concentration of other major myelin proteins was not significantly changed. Western blot analysis revealed an almost 6-fold increase of Opalin in myelin of Fa2h-/- mice aged 21-23 months. A concurrent unaltered Opalin gene expression suggested a decreased turnover of the Opalin protein in Fa2h-/- mice. Supporting this hypothesis, Opalin protein half-life was reduced significantly when expressed in CHO cells synthesizing 2-hydroxylated sulfatide, compared to cells synthesizing only non-hydroxylated sulfatide. Degradation of Opalin was inhibited by inhibitors of lysosomal degradation but unaffected by proteasome inhibitors. Taken together, these results reveal a new function of 2-hydroxylated sphingolipids namely affecting the turnover of a myelin membrane protein. This may play a role in the pathogenesis of SPG35.
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Affiliation(s)
- Robert Hardt
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn 53115, Germany
| | - Silvia Jordans
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn 53115, Germany
| | - Dominic Winter
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn 53115, Germany
| | - Volkmar Gieselmann
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn 53115, Germany
| | - Lihua Wang-Eckhardt
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn 53115, Germany
| | - Matthias Eckhardt
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn 53115, Germany
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6
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Sun L, Yang X, Huang X, Yao Y, Wei X, Yang S, Zhou D, Zhang W, Long Z, Xu X, Zhu X, He S, Su X. 2-Hydroxylation of Fatty Acids Represses Colorectal Tumorigenesis and Metastasis via the YAP Transcriptional Axis. Cancer Res 2020; 81:289-302. [PMID: 33203703 DOI: 10.1158/0008-5472.can-20-1517] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 09/16/2020] [Accepted: 11/12/2020] [Indexed: 11/16/2022]
Abstract
Alteration in lipid composition is an important metabolic adaptation by cancer cells to support tumorigenesis and metastasis. Fatty acid 2-hydroxylase (FA2H) introduces a chiral hydroxyl group at the second carbon of fatty acid (FA) backbones and influences lipid structures and metabolic signaling. However, the underlying mechanisms through which FA 2-hydroxylation is coupled to metabolic adaptation and tumor growth remain elusive. Here, we show that FA2H regulates specific metabolic reprogramming and oncogenic signaling in the development of colorectal cancer. FA2H is highly expressed in normal colorectal tissues. Assessments through deciphering both published high-throughput data and curated human colorectal cancer samples revealed significant suppression of FA2H in tumors, which is correlated with unfavorable prognosis. Experiments with multiple models of genetic manipulation or treatment with an enzymatic product of FA2H, (R)-2-hydroxy palmitic acid, demonstrated that FA 2-hydroxylation inhibits colorectal cancer cell proliferation, migration, epithelial-to-mesenchymal transition progression, and tumor growth. Bioinformatics analysis suggested that FA2H functions through AMP-activated protein kinase/Yes-associated protein (AMPK/YAP) pathway, which was confirmed in colorectal cancer cells, as well as in tumors. Lipidomics analysis revealed an accumulation of polyunsaturated fatty acids in cells with FA2H overexpression, which may contribute to the observed nutrient deficiency and AMPK activation. Collectively, these data demonstrate that FA 2-hydroxylation initiates a metabolic signaling cascade to suppress colorectal tumor growth and metastasis via the YAP transcriptional axis and provides a strategy to improve colorectal cancer treatment. SIGNIFICANCE: These findings identify a novel metabolic mechanism regulating the tumor suppressor function of FA 2-hydroxylation in colorectal cancer.
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Affiliation(s)
- Liang Sun
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, P.R. China.,Department of General Surgery, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, P.R. China
| | - Xiaoqin Yang
- Department of Bioinformatics, Soochow University Medical College, Suzhou, Jiangsu, P.R. China
| | - Xiaoheng Huang
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, P.R. China
| | - Yizhou Yao
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, P.R. China.,Department of General Surgery, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, P.R. China
| | - Xiangyu Wei
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, P.R. China
| | - Shugao Yang
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, P.R. China
| | - Diyuan Zhou
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, P.R. China.,Department of General Surgery, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, P.R. China
| | - Wei Zhang
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri
| | - Zhimin Long
- Shanghai Sciex Analytical Instrument Trading Co., Shanghai, P.R. China
| | - Xiaoyan Xu
- Shanghai Sciex Analytical Instrument Trading Co., Shanghai, P.R. China
| | - Xinguo Zhu
- Department of General Surgery, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, P.R. China.
| | - Songbing He
- Department of General Surgery, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, P.R. China
| | - Xiong Su
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, P.R. China. .,Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri
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Ali H, Yamashita R, Morishige JI, Morito K, Kakiuchi N, Hayashi J, Aihara M, Kawakami R, Tsuchiya K, Tanaka T. Mass Spectrometric Analysis of Sphingomyelin with N-α-Hydroxy Fatty Acyl Residue in Mouse Tissues. Lipids 2020; 56:181-188. [PMID: 32996178 DOI: 10.1002/lipd.12285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 09/06/2020] [Accepted: 09/14/2020] [Indexed: 11/09/2022]
Abstract
Sphingomyelin (SM) with N-α-hydroxy fatty acyl residues (hSM) has been shown to occur in mammalian skin and digestive epithelia. However, the metabolism and physiological relevance of this characteristic SM species have not been fully elucidated yet. Here, we show methods for mass spectrometric characterization and quantification of hSM. The hSM in mouse skin was isolated by TLC. The hydroxy hexadecanoyl residue was confirmed by electron impact ionization-induced fragmentation in gas chromatography-mass spectrometry. Mass shift analysis of acetylated hSM by time of flight mass spectrometry revealed the number of hydroxyl groups in the molecule. After correcting the difference in detection efficacy, hSM in mouse skin and intestinal mucosa were quantified by liquid chromatography-tandem mass spectrometry, and found to be 16.5 ± 2.0 and 0.8 ± 0.4 nmol/μmol phospholipid, respectively. The methods described here are applicable to biological experiments on hSM in epithelia of the body surface and digestive tract.
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Affiliation(s)
- Hanif Ali
- Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Ryouhei Yamashita
- Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Jun-Ichi Morishige
- Department of Cellular and Molecular Function Analysis, Kanazawa University Graduate School of Medical Sciences, Kanazawa, 920-8640, Japan
| | - Katsuya Morito
- Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Naoya Kakiuchi
- Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Junji Hayashi
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, 770-8513, Japan
| | - Mutsumi Aihara
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, 770-8513, Japan
| | - Ryushi Kawakami
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, 770-8513, Japan
| | - Koichiro Tsuchiya
- Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Tamotsu Tanaka
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, 770-8513, Japan
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Hashimoto N, Ito S, Tsuchida A, Bhuiyan RH, Okajima T, Yamamoto A, Furukawa K, Ohmi Y, Furukawa K. The ceramide moiety of disialoganglioside (GD3) is essential for GD3 recognition by the sialic acid-binding lectin SIGLEC7 on the cell surface. J Biol Chem 2019; 294:10833-10845. [PMID: 31138648 DOI: 10.1074/jbc.ra118.007083] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 05/18/2019] [Indexed: 12/21/2022] Open
Abstract
To analyze the binding specificity of a sialic acid-recognizing lectin, sialic acid-binding Ig-like lectin 7 (SIGLEC7), to disialyl gangliosides (GD3s), here we established GD3-expressing cells by introducing GD3 synthase (GD3S or ST8SIA1) cDNA into a colon cancer cell line, DLD-1, that expresses no ligands for the recombinant protein SIGLEC7-Fc. SIGLEC7-Fc did not recognize newly-expressed GD3 on DLD-1 cells, even though GD3 was highly expressed, as detected by an anti-GD3 antibody. Because milk-derived GD3 could be recognized by this fusion protein when incorporated onto the surface of DLD-1 cells, we compared the ceramides in DLD-1-generated and milk-derived GD3s to identify the SIGLEC7-specific GD3 structures on the cell membrane, revealing that SIGLEC7 recognizes only GD3-containing regular ceramides but not phytoceramides. This was confirmed by knockdown/knockout of the sphingolipid delta(4)-desaturase/C4-monooxygenase (DES2) gene, involved in phytoceramide synthesis, disclosing that DES2 inhibition confers SIGLEC7 binding. Furthermore, knocking out fatty acid 2-hydroxylase also resulted in the emergence of SIGLEC7 binding to the cell surface. To analyze the effects of binding between SIGLEC7 and various GD3 species on natural killer function, we investigated cytotoxicity of peripheral blood mononuclear cells from healthy donors toward GD3S-transfected DLD-1 (DLD-1-GD3S) cells and DLD-1-GD3S cells with modified ceramides. We found that cytotoxicity is suppressed in DLD-1-GD3S cells with dehydroxylated GD3s. These results indicate that the ceramide structures in glycosphingolipids affect SIGLEC7 binding and distribution on the cell surface and influence cell sensitivity to killing by SIGLEC7-expressing effector cells.
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Affiliation(s)
- Noboru Hashimoto
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-0065, Japan,; Department of Tissue Regeneration, Tokushima University Graduate School of Biomedical Sciences, 3-18-5, Kuramoto-cho, Tokushima 770-8504, Japan
| | - Shizuka Ito
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-0065, Japan
| | - Akiko Tsuchida
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-0065, Japan
| | - Robiul H Bhuiyan
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-0065, Japan,; Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, 1200 Matsumoto, Kasugai, Aichi 487-8501, Japan, and
| | - Tetsuya Okajima
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-0065, Japan
| | - Akihito Yamamoto
- Department of Tissue Regeneration, Tokushima University Graduate School of Biomedical Sciences, 3-18-5, Kuramoto-cho, Tokushima 770-8504, Japan
| | - Keiko Furukawa
- Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, 1200 Matsumoto, Kasugai, Aichi 487-8501, Japan, and
| | - Yuhsuke Ohmi
- Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, 1200 Matsumoto, Kasugai, Aichi 487-8501, Japan, and
| | - Koichi Furukawa
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-0065, Japan,; Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, 1200 Matsumoto, Kasugai, Aichi 487-8501, Japan, and.
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9
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Marquês JT, Marinho HS, de Almeida RF. Sphingolipid hydroxylation in mammals, yeast and plants – An integrated view. Prog Lipid Res 2018; 71:18-42. [DOI: 10.1016/j.plipres.2018.05.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/11/2018] [Accepted: 05/04/2018] [Indexed: 02/07/2023]
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10
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Seo C, Kim Y, Lee HS, Kim SZ, Paik MJ. Metabolic Profiling of Aliphatic, hydroxy, and Methyl-Branched Fatty Acids in Human Plasma by Gas Chromatography–Mass Spectrometry. ANAL LETT 2017. [DOI: 10.1080/00032719.2017.1363769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Chan Seo
- College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, Republic of Korea
| | - Youngbae Kim
- College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, Republic of Korea
| | - Hyeon-Seong Lee
- College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, Republic of Korea
| | - Sook Za Kim
- Kim Sook Za’s Children Hospital and Korea Genetic Research Center, Cheongju, Republic of Korea
| | - Man-Jeong Paik
- College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, Republic of Korea
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Facchini L, Losito I, Cataldi TRI, Palmisano F. Ceramide lipids in alive and thermally stressed mussels: an investigation by hydrophilic interaction liquid chromatography-electrospray ionization Fourier transform mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2016; 51:768-781. [PMID: 27479706 DOI: 10.1002/jms.3832] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 07/25/2016] [Accepted: 07/28/2016] [Indexed: 06/06/2023]
Abstract
Hydrophilic interaction liquid chromatography coupled to electrospray ionization-Fourier transform mass spectrometry was employed to study ceramide lipids occurring in mussels of sp. Mytilus galloprovincialis. Lipid extracts from alive mussels and mussels deliberately subjected to specific thermal treatments were analyzed. In particular, single and tandem MS measurements were performed on a hybrid quadrupole-Orbitrap mass spectrometer and then complemented by MS(n) analyses (n = 2, 3) achieved by a linear ion trap mass spectrometer. This approach enabled the characterization of 66 ceramide lipids, encompassing ceramide phosphoethanolamines (CPE), ceramide aminoethylphosphonates (CAEP) and N-monomethylated CAEP. The sphingoid and acyl chains of each ceramide lipid could be distinctly recognized in terms of numbers of carbon atoms and C=C bonds, and indications on the possible location of the latter on the sphingoid chain could be often inferred from fragmentation patterns. The occurrence of several species hydroxylated on the α carbon of the acyl chain was also discovered. On the other hand, the sphingoid chain of ceramide lipids was never found to be involved in oxidation processes, unless forced exposure of the mussel lipid extracts to atmospheric oxygen was performed. CPE(d19:3/16:0) and its hydroxylated form, CPE(d19:3/2-OH-16:0), were found to be the prevailing species among CPE, whereas CAEP(d18:2/16:0), CAEP(d19:3/16:0) and CAEP(d19:3/2-OH-16:0) were the most abundant CAEP. Finally, ceramide lipids showed a remarkably higher stability, compared with glycerophospholipids, in mussels subjected to different thermal treatments. This finding opens interesting perspectives on the role of ceramide-based lipids in the adaptation of aquatic organisms to thermal stresses. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Laura Facchini
- Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70126, Bari, Italy
| | - Ilario Losito
- Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70126, Bari, Italy
- Centro Interdipartimentale SMART, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70126, Bari, Italy
| | - Tommaso R I Cataldi
- Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70126, Bari, Italy
- Centro Interdipartimentale SMART, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70126, Bari, Italy
| | - Francesco Palmisano
- Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70126, Bari, Italy
- Centro Interdipartimentale SMART, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70126, Bari, Italy
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12
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Meyer E, Kurian MA, Hayflick SJ. Neurodegeneration with Brain Iron Accumulation: Genetic Diversity and Pathophysiological Mechanisms. Annu Rev Genomics Hum Genet 2015; 16:257-79. [PMID: 25973518 DOI: 10.1146/annurev-genom-090314-025011] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neurodegeneration with brain iron accumulation (NBIA) comprises a heterogeneous group of progressive disorders with the common feature of excessive iron deposition in the brain. Over the last decade, advances in sequencing technologies have greatly facilitated rapid gene discovery, and several single-gene disorders are now included in this group. Identification of the genetic bases of the NBIA disorders has advanced our understanding of the disease processes caused by reduced coenzyme A synthesis, impaired lipid metabolism, mitochondrial dysfunction, and defective autophagy. The contribution of iron to disease pathophysiology remains uncertain, as does the identity of a putative final common pathway by which the iron accumulates. Ongoing elucidation of the pathogenesis of each NBIA disorder will have significant implications for the identification and design of novel therapies to treat patients with these disorders.
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Affiliation(s)
- Esther Meyer
- Molecular Neurosciences, Developmental Neurosciences Programme, Institute of Child Health, University College London, London WC1N 1EH, United Kingdom; ,
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13
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Delving into the complexity of hereditary spastic paraplegias: how unexpected phenotypes and inheritance modes are revolutionizing their nosology. Hum Genet 2015; 134:511-38. [PMID: 25758904 PMCID: PMC4424374 DOI: 10.1007/s00439-015-1536-7] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 02/23/2015] [Indexed: 12/11/2022]
Abstract
Hereditary spastic paraplegias (HSP) are rare neurodegenerative diseases sharing the degeneration of the corticospinal tracts as the main pathological characteristic. They are considered one of the most heterogeneous neurological disorders. All modes of inheritance have been described for the 84 different loci and 67 known causative genes implicated up to now. Recent advances in molecular genetics have revealed clinico-genetic heterogeneity of these disorders including their clinical and genetic overlap with other diseases of the nervous system. The systematic analysis of a large set of genes, including exome sequencing, is unmasking unusual phenotypes or inheritance modes associated with mutations in HSP genes and related genes involved in various neurological diseases. A new nosology may emerge after integration and understanding of these new data to replace the current classification. Collectively, functions of the known genes implicate the disturbance of intracellular membrane dynamics and trafficking as the consequence of alterations of cytoskeletal dynamics, lipid metabolism and organelle structures, which represent in fact a relatively small number of cellular processes that could help to find common curative approaches, which are still lacking.
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14
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Colombelli C, Aoun M, Tiranti V. Defective lipid metabolism in neurodegeneration with brain iron accumulation (NBIA) syndromes: not only a matter of iron. J Inherit Metab Dis 2015; 38:123-36. [PMID: 25300979 DOI: 10.1007/s10545-014-9770-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 09/02/2014] [Accepted: 09/09/2014] [Indexed: 12/29/2022]
Abstract
Neurodegeneration with brain iron accumulation (NBIA) is a group of devastating and life threatening rare diseases. Adult and early-onset NBIA syndromes are inherited as X-chromosomal, autosomal dominant or recessive traits and several genes have been identified as responsible for these disorders. Among the identified disease genes, only two code for proteins directly involved in iron metabolism while the remaining NBIA genes encode proteins with a wide variety of functions ranging from fatty acid metabolism and autophagy to still unknown activities. It is becoming increasingly evident that many neurodegenerative diseases are associated with metabolic dysfunction that often involves altered lipid metabolism. This is not surprising since neurons have a peculiar and heterogeneous lipid composition critical for the development and correct functioning of the nervous system. This review will focus on specific NBIA forms, namely PKAN, CoPAN, PLAN, FAHN and MPAN, which display an interesting link between neurodegeneration and alteration of phospholipids and sphingolipids metabolism, mitochondrial morphology and membrane remodelling.
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Affiliation(s)
- Cristina Colombelli
- Unit of Molecular Neurogenetics - Pierfranco and Luisa Mariani Centre for the Study of Mitochondrial Disorders in Children, Foundation IRCCS Neurological Institute "Carlo Besta", Via Temolo 4, 20126, Milan, Italy
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15
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Kota V, Hama H. 2'-Hydroxy ceramide in membrane homeostasis and cell signaling. Adv Biol Regul 2013; 54:223-30. [PMID: 24139861 DOI: 10.1016/j.jbior.2013.09.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Accepted: 09/15/2013] [Indexed: 01/25/2023]
Abstract
Ceramide is a precursor of complex sphingolipids and also plays important roles in cell signaling. With the advances in lipid analytical technologies, the structural diversity of ceramide species have become evident, and the complexity of cellular metabolism and function associated with distinct ceramide species is beginning to be revealed. One of the common structural variations of ceramide is 2'-hydroxylation of the N-acyl chain. Fatty acid 2-hydroxylase (FA2H) is one of the enzymes that introduce the hydroxyl group during de novo synthesis of ceramide. FA2H is essential for the normal functioning of the nervous system, as evidenced by demyelinating disorder associated with FA2H mutations in humans and mice. Studies of Fa2h mutant mice indicate that lack of 2'-hydroxy galactosylceramide in the myelin membrane results in loss of long-term stability of myelin and eventual demyelination. FA2H also regulates differentiation of various cell types (epidermal keratinocytes, schwannoma cells, adipocytes). When provided exogenously, ceramide induces apoptosis in many cell types. Interestingly, the effective concentration of 2'-hydroxy ceramide that induces apoptosis is significantly lower compared to non-hydroxy ceramide, and cells die much more rapidly, suggesting that 2'-hydroxy ceramide can mediate proapoptotic signaling distinct from non-hydroxy ceramide. Collectively, current evidence clearly shows that 2'-hydroxy ceramide and 2'-hydroxy complex sphingolipids have unique functions in membrane homeostasis and cell signaling that could not be substituted by non-hydroxy counterparts.
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Affiliation(s)
- Venkatesh Kota
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA
| | - Hiroko Hama
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA.
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16
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Kota V, Dhople VM, Fullbright G, Smythe NM, Szulc ZM, Bielawska A, Hama H. 2'-hydroxy C16-ceramide induces apoptosis-associated proteomic changes in C6 glioma cells. J Proteome Res 2013; 12:4366-75. [PMID: 23987666 DOI: 10.1021/pr4003432] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ceramide is a bioactive sphingolipid involved in regulation of numerous cell signaling pathways. Evidence is accumulating that differences in ceramide structure, such as N-acyl chain length and desaturation of sphingoid base, determine the biological activities of ceramide. Using synthetic (R)-2'-hydroxy-C16-ceramide, which is the naturally occurring stereoisomer, we demonstrate that this ceramide has more potent pro-apoptotic activity compared to its (S) isomer or non-hydroxylated C16-ceramide. Upon exposure to (R)-2'-hydroxy-ceramide, C6 glioma cells rapidly underwent apoptosis as indicated by caspase-3 activation, PARP cleavage, chromatin condensation, and annexin V stain. A 2D gel proteomics analysis identified 28 proteins whose levels were altered during the initial 3 h of exposure. Using the list of 28 proteins, we performed a software-assisted pathway analysis to identify possible signaling events that would result in the observed changes. The result indicated that Akt and MAP kinase pathways are among the possible pathways regulated by (R)-2'-hydroxy-ceramide. Experimental validation confirmed that 2'-hydroxy-ceramide significantly altered phosphorylation status of Akt and its downstream effector GSK3β, as well as p38, ERK1/2, and JNK1/2 MAP kinases. Unexpectedly, robust phosphorylation of Akt was observed within 1 h of exposure to 2'-hydroxy-ceramide, followed by dephosphorylation. Phosphorylation status of MAPKs showed a complex pattern, in which rapid phosphorylation of ERK1/2 was followed by dephosphorylation of p38 and ERK1/2 and phosphorylation of the 46 kDa isoform of JNK1/2. These data indicate that (R)-2'-hydroxy-ceramide regulates multiple signaling pathways by affecting protein kinases and phosphatases with kinetics distinct from that of the extensively studied non-hydroxy-ceramide or its unnatural stereoisomer.
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Affiliation(s)
- Venkatesh Kota
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina , Charleston, South Carolina 29425, United States
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17
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Abstract
Abnormal accumulation of brain iron has been detected in various neurodegenerative diseases, but the contribution of iron overload to pathology remains unclear. In a group of distinctive brain iron overload diseases known as 'neurodegeneration with brain iron accumulation' (NBIA) diseases, nine disease genes have been identified. Brain iron accumulation is observed in the globus pallidus and other brain regions in NBIA diseases, which are often associated with severe dystonia and gait abnormalities. Only two of these diseases, aceruloplasminaemia and neuroferritinopathy, are directly caused by abnormalities in iron metabolism, mainly in astrocytes and neurons, respectively. Understanding the early molecular pathophysiology of these diseases should aid insights into the role of iron and the design of specific therapeutic approaches.
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18
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Biological functions of sphingomyelins. Prog Lipid Res 2013; 52:424-37. [PMID: 23684760 DOI: 10.1016/j.plipres.2013.05.001] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 04/12/2013] [Accepted: 05/02/2013] [Indexed: 12/14/2022]
Abstract
Sphingomyelin (SM) is a dominant sphingolipid in membranes of mammalian cells and this lipid class is specifically enriched in the plasma membrane, the endocytic recycling compartment, and the trans Golgi network. The distribution of SM and cholesterol among cellular compartments correlate. Sphingolipids have extensive hydrogen-bonding capabilities which together with their saturated nature facilitate the formation of sphingolipid and SM-enriched lateral domains in membranes. Cholesterol prefers to interact with SMs and this interaction has many important functional consequences. In this review, the synthesis, regulation, and intracellular distribution of SMs are discussed. The many direct roles played by membrane SM in various cellular functions and processes will also be discussed. These include involvement in the regulation of endocytosis and receptor-mediated ligand uptake, in ion channel and G-protein coupled receptor function, in protein sorting, and functioning as receptor molecules for various bacterial toxins, and for non-bacterial pore-forming toxins. SM is also an important constituent of the eye lens membrane, and is believed to participate in the regulation of various nuclear functions. SM is an independent risk factor in the development of cardiovascular disease, and new studies have shed light on possible mechanism behind its role in atherogenesis.
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19
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Peter Slotte J. Molecular properties of various structurally defined sphingomyelins -- correlation of structure with function. Prog Lipid Res 2013; 52:206-19. [PMID: 23295259 DOI: 10.1016/j.plipres.2012.12.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 12/20/2012] [Accepted: 12/21/2012] [Indexed: 01/10/2023]
Abstract
Sphingomyelins are important phospholipids in plasma membranes of most cells. Because of their dominantly saturated nature, they affect the lateral structure of membranes, and contribute to the regulation of cholesterol distribution within membranes, and in cells. However, the abundance of molecular species present in cells also implies that sphingomyelins have other, more specific functions. Many of these functions are currently unknown, but are under extensive study. Mostly model membrane studies have shown that sphingomyelins (and other sphingolipids), in contrast to glycerophospholipids, have important hydrogen bonding properties which in several important ways confer specific functional properties to this abundant class of membrane phospholipids. The often very asymmetric nature of sphingomyelins, arising from mismatch in length between the long chain base and N-acyl chains, also impose specific properties (e.g., interdigitation) to sphingomyelins not seen with glycerophospholipids. In this review, the latest sphingomyelin literature will be scrutinized, and an effort will be made to correlate the molecular structure of sphingomyelin with functional properties. In particular, the effects of head group properties, interfacial hydrogen bonding, long chain base hydroxylation, N-acyl chain hydroxylation, and N-acyl chain methyl-branching will be discussed.
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Affiliation(s)
- J Peter Slotte
- Biochemistry, Department of Biosciences, Åbo Akademi University, Tykistökatu 6A, 20520 Turku, Finland.
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Schneider SA, Bhatia KP. Excess iron harms the brain: the syndromes of neurodegeneration with brain iron accumulation (NBIA). J Neural Transm (Vienna) 2012; 120:695-703. [PMID: 23212724 DOI: 10.1007/s00702-012-0922-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 11/11/2012] [Indexed: 12/14/2022]
Abstract
Regulation of iron metabolism is crucial: both iron deficiency and iron overload can cause disease. In recent years, our understanding of the syndromes of Neurodegeneration with Brain Iron Accumulation (NBIA) continues to grow considerably. These are characterized by excessive iron deposition in the brain, mainly the basal ganglia. Pantothenate kinase-associated neurodegeneration (PKAN, NBIA1) and PLA2G6-associated neurodegeneration (PLAN, NBIA2) are the core syndromes, but several other genetic causes have been identified (including FA2H, C19orf12, ATP13A2, CP and FTL). These conditions show a wide clinical and pathological spectrum, with clinical overlap between the different NBIA disorders and other diseases including spastic paraplegias, leukodystrophies, and neuronal ceroid lipofuscinosis. Lewy body pathology was confirmed in some clinical subtypes (C19orf12-associated neurodegeneration and PLAN). Research aims at disentangling the various NBIA genes and their related pathways to move towards pathogenesis-targeted therapies. Until then treatment remains symptomatic. Here we will introduce the group of NBIA syndromes and review the main clinical features and investigational findings.
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Affiliation(s)
- Susanne A Schneider
- Department of Neurology, University Kiel, Arnold Heller Str. 3, 24105, Kiel, Germany.
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21
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Breimer ME, Hansson GC, Karlsson KA, Larson G, Leffler H. Glycosphingolipid composition of epithelial cells isolated along the villus axis of small intestine of a single human individual. Glycobiology 2012; 22:1721-30. [DOI: 10.1093/glycob/cws115] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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22
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Guo L, Zhang X, Zhou D, Okunade AL, Su X. Stereospecificity of fatty acid 2-hydroxylase and differential functions of 2-hydroxy fatty acid enantiomers. J Lipid Res 2012; 53:1327-35. [PMID: 22517924 DOI: 10.1194/jlr.m025742] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
FA 2-hydroxylase (FA2H) is an NAD(P)H-dependent enzyme that initiates FA α oxidation and is also responsible for the biosynthesis of 2-hydroxy FA (2-OH FA)-containing sphingolipids in mammalian cells. The 2-OH FA is chiral due to the asymmetric carbon bearing the hydroxyl group. Our current study performed stereochemistry investigation and showed that FA2H is stereospecific for the production of (R)-enantiomers. FA2H knockdown in adipocytes increases diffusional mobility of raft-associated lipids, leading to reduced GLUT4 protein level, glucose uptake, and lipogenesis. The effects caused by FA2H knockdown were reversed by treatment with exogenous (R)-2-hydroxy palmitic acid, but not with the (S)-enantiomer. Further analysis of sphingolipids demonstrated that the (R)-enantiomer is enriched in hexosylceramide whereas the (S)-enantiomer is preferentially incorporated into ceramide, suggesting that the observed differential effects are in part due to synthesis of sphingolipids containing different 2-OH FA enantiomers. These results may help clarify the mechanisms underlying the recently identified diseases associated with FA2H mutations in humans and may lead to potential pharmaceutical and dietary treatments. This study also provides critical information to help study functions of 2-OH FA enantiomers in FA α oxidation and possibly other sphingolipid-independent pathways.
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Affiliation(s)
- Lin Guo
- Department of Internal Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110, USA
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