Mass spectrometric analysis reveals changes in phospholipid, neutral sphingolipid and sulfatide molecular species in progressive epilepsy with mental retardation, EPMR, brain: A case study

Institute of Biomedicine, Department of Biochemistry, University of Helsinki, Helsinki, Finland.
Journal of Neurochemistry (Impact Factor: 4.28). 12/2005; 95(3):609-17. DOI: 10.1111/j.1471-4159.2005.03376.x
Source: PubMed

ABSTRACT Progressive epilepsy with mental retardation, EPMR, belongs to a group of inherited neurodegenerative disorders, the neuronal ceroid lipofuscinoses. The CLN8 gene that underlies EPMR encodes a novel transmembrane protein that localizes to the endoplasmic reticulum (ER) and ER-Golgi intermediate compartment. Recently, CLN8 was linked to a large eukaryotic protein family of TLC (TRAM, Lag1, CLN8) domain homologues with postulated functions in lipid synthesis, transport or sensing. By using liquid chromatography/mass spectrometry we analysed molecular species of major phosholipid and simple sphingolipid classes from cerebral samples of two EPMR patients representing a progressive and advanced state of the disease. The progressive state brain showed reduced levels of ceramide, galactosyl- and lactosylceramide and sulfatide as well as a decrease in long fatty acyl chain containing molecular species within these classes. Among glycerophospholipid classes, an increase in species containing polyunsaturated acyl chains was detected especially in phosphatidylserines and phosphatidylethanolamines. By contrast, saturated and monounsaturated species were overrepresented among phosphatidylserine, phosphatidylethanolamine and phosphatidylinositol classes in the advanced state sample. The observed changes in brain sphingo- and phospholipid molecular profiles may result in altered membrane stability, lipid peroxidation, vesicular trafficking or neurotransmission and thus may contribute to the progression of the molecular pathogenesis of EPMR.

Download full-text


Available from: Pentti Somerharju, Oct 13, 2014
20 Reads
  • Source
    • "At least 24 different mutations, either deletion or missense, are linked to CLN8 diseases and mostly to the vLINCL form [1]. Using the naturally-occurring mnd (motor neuron degeneration) mouse model (Cln8 mnd mouse) exhibiting a disease phenotype similar to that of CLN8-vLINCL [17] [21] [22], numerous studies have shown altered lipid metabolism, oxidative and ER stresses, mitochondrial dysfunction, defects in calcium homeostasis, inflammation and apoptosis [23] [24] [25] [26] [27] [28] [29]. Changes in brain lipids and ER-stress responses in fibroblast cells have been also reported in EPMR patients [30] [31]. However, due to the still undefined CLN8 function, the primary defect underlying CLN8- associated diseases remains an open question. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Neuronal ceroid lipofuscinoses (NCLs) are a genetically heterogeneous group of neurodegenerative diseases characterized by cognitive and motor decline, epilepsy, visual loss and by lysosomal autofluorescent inclusions. Two distinct clinical phenotypes, the progressive epilepsy with mental retardation (EPMR) and a late-infantile variant of NCLs (CLN8-vLINCL) are associated with mutations in the CLN8 gene that encodes a transmembrane protein predominantly located to the endoplasmic reticulum (ER). To gain insight into the function of CLN8 protein, we employed the split-ubiquitin membrane-based yeast two-hybrid (MYTH) system, which detects protein-protein interactions in a membrane environment, using the full-length human CLN8 as bait and a human brain cDNA library as prey. We identified several potential protein partners of CLN8 and especially referred to VAPA, c14orf1/hERG28, STX8, GATE16, BNIP3 and BNIP3L proteins that are associated with biologically relevant processes such as synthesis and transport of lipids, vesicular/membrane trafficking, autophagy/mitophagy and apoptosis. Interactions of CLN8 with VAPA and GATE16 were further validated by co-immunoprecipitation and co-localization assays in mammalian cells. Using a new C-terminal-oriented CLN8 antibody, CLN8-VAPA interaction was also confirmed by co-staining in close spatial proximity within different CNS tissues. The results of this study shed light on potential interactome networks of CLN8 and provide a powerful starting point for understanding protein function(s) and molecular aspects of diseases associated with CLN8 deficiency.
    Biochimica et Biophysica Acta 11/2012; 1833(3). DOI:10.1016/j.bbamcr.2012.10.030 · 4.66 Impact Factor
  • Source
    • "Elevation of sulfatide by 30%–40% has also been found in the superior frontal and cerebellar gray matter in Parkinson's disease patients (Eckhardt, 2008). By contrast, substantial decrease in SF has been observed in a case of progressive epilepsy with mental retardation (Hermansson et al., 2005) and in the brain and cerebrospinal fluid of Alzheimer's disease patients (Eckhardt, 2008; Han, 2007; 2010). Not surprisingly, sulfatide homeostasis is critical for the normal function of central and peripheral nerves. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Human glycolipid transfer protein (GLTP) fold represents a novel structural motif for lipid binding/transfer and reversible membrane translocation. GLTPs transfer glycosphingolipids (GSLs) that are key regulators of cell growth, division, surface adhesion, and neurodevelopment. Herein, we report structure-guided engineering of the lipid binding features of GLTP. New crystal structures of wild-type GLTP and two mutants (D48V and A47D‖D48V), each containing bound N-nervonoyl-sulfatide, reveal the molecular basis for selective anchoring of sulfatide (3-O-sulfo-galactosylceramide) by D48V-GLTP. Directed point mutations of "portal entrance" residues, A47 and D48, reversibly regulate sphingosine access to the hydrophobic pocket via a mechanism that could involve homodimerization. "Door-opening" conformational changes by phenylalanines within the hydrophobic pocket are revealed during lipid encapsulation by new crystal structures of bona fide apo-GLTP and GLTP complexed with N-oleoyl-glucosylceramide. The development of "engineered GLTPs" with enhanced specificity for select GSLs provides a potential new therapeutic approach for targeting GSL-mediated pathologies.
    Structure 11/2011; 19(11):1644-54. DOI:10.1016/j.str.2011.09.011 · 5.62 Impact Factor
  • Source
    • "Thus, determining the downstream alterations in biochemical and cellular pathways brought on by the primary gene defect is essential for a complete understanding of pathogenesis. Among these, secondary changes in the lipid composition of brain material for CLN1, CLN2, CLN3 and CLN8 patients and in the ovine CLN6 model have been reported (Bourré et al. 1979; Palmer et al. 1985; Svennerholm et al. 1987; Käkelä et al. 2003; Hermansson et al. 2005a). In this study, lipid profiles have been examined in different areas of brains from mouse models for CLN6 [nclf; (Bronson et al. 1998)] and ctsd)/) (Saftig et al. 1995), differing in the severity of the disease. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The neuronal ceroid lipofuscinoses comprise a group of inherited severe neurodegenerative lysosomal disorders characterized by lysosomal dysfunction and massive accumulation of fluorescent lipopigments and aggregated proteins. To examine the role of lipids in neurodegenerative processes of these diseases, we analysed phospho- and glycolipids in the brains of ctsd-/- and nclf mice, disease models of cathepsin D and CLN6 deficiency, respectively. Both ctsd-/- and nclf mice exhibited increased levels of GM2 and GM3 gangliosides. Immunohistochemically GM2 and GM3 staining was found preferentially in neurons and glial cells, respectively, of ctsd-/- mice. Of particular note, a 20-fold elevation of the unusual lysophospholipid bis(monoacylglycero)phosphate was specifically detected in the brain of ctsd-/- mice accompanied with sporadic accumulation of unesterified cholesterol in distinct cells. The impaired processing of the sphingolipid activator protein precursor, an in vitro cathepsin D substrate, in the brain of ctsd-/- mice may provide the mechanistic link to the storage of lipids. These studies show for the first time that cathepsin D regulates the lysosomal phospho- and glycosphingolipid metabolism suggesting that defects in the composition, trafficking and/or recycling of membrane components along the late endocytic pathway may be critical for the pathogenesis of early onset neuronal ceroid lipofuscinoses.
    Journal of Neurochemistry 07/2008; 106(3):1415-25. DOI:10.1111/j.1471-4159.2008.05497.x · 4.28 Impact Factor
Show more