PCSK9 Affects Astrocyte Cholesterol Metabolism and Reduces Neuron Cholesterol Supplying In Vitro: Potential Implications in Alzheimer's Disease

The Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) involvement in Alzheimer's disease (AD) is poorly investigated. We evaluated the in vitro PCSK9 modulation of astrocyte cholesterol metabolism and neuronal cholesterol supplying, which is fundamental for neuronal functions. Moreover, we investigated PCSK9 neurotoxic effects. In human astrocytoma cells, PCSK9 reduced cholesterol content (-20%; p < 0.05), with a greater effect in presence of beta amyloid peptide (A beta) (-37%; p < 0.01). PCSK9 increased cholesterol synthesis and reduced the uptake of apoE-HDL-derived cholesterol (-36%; p < 0.0001), as well as the LDL receptor (LDLR) and the apoE receptor 2 (ApoER2) expression (-66% and -31%, respectively; p < 0.01). PCSK9 did not modulate ABCA1- and ABCG1-cholesterol efflux, ABCA1 levels, or membrane cholesterol. Conversely, ABCA1 expression and activity, as well as membrane cholesterol, were reduced by A beta (p < 0.05). In human neuronal cells, PCSK9 reduced apoE-HDL-derived cholesterol uptake (-41%; p < 0.001) and LDLR/apoER2 expression (p < 0.05). Reduced cholesterol internalization occurred also in PCSK9-overexpressing neurons exposed to an astrocyte-conditioned medium (-39%; p < 0.001). PCSK9 reduced neuronal cholesterol content overall (-29%; p < 0.05) and increased the A beta-induced neurotoxicity (p < 0.0001). Our data revealed an interfering effect of PCSK9, in cooperation with A beta, on brain cholesterol metabolism leading to neuronal cholesterol reduction, a potentially deleterious effect. PCSK9 also exerted a neurotoxic effect, and thus represents a potential pharmacological target in AD

ELOVL5 mutations cause spinocerebellar ataxia 38.

Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal-dominant neurodegenerative disorders involving the cerebellum and 23 different genes. We mapped SCA38 to a 56 Mb region on chromosome 6p in a SCA-affected Italian family by whole-genome linkage analysis. Targeted resequencing identified a single missense mutation (c.689G>T [p.Gly230Val]) in ELOVL5. Mutation screening of 456 independent SCA-affected individuals identified the same mutation in two further unrelated Italian families. Haplotyping showed that at least two of the three families shared a common ancestor. One further missense variant (c.214C>G [p.Leu72Val]) was found in a French family. Both missense changes affect conserved amino acids, are predicted to be damaging by multiple bioinformatics tools, and were not identified in ethnically matched controls or within variant databases. ELOVL5 encodes an elongase involved in the synthesis of polyunsaturated fatty acids of the ω3 and ω6 series. Arachidonic acid and docosahexaenoic acid, two final products of the enzyme, were reduced in the serum of affected individuals. Immunohistochemistry on control mice and human brain demonstrated high levels in Purkinje cells. In transfection experiments, subcellular localization of altered ELOVL5 showed a perinuclear distribution with a signal increase in the Golgi compartment, whereas the wild-type showed a widespread signal in the endoplasmic reticulum. SCA38 and SCA34 are examples of SCAs due to mutations in elongase-encoding genes, emphasizing the importance of fatty-acid metabolism in neurological diseases

NMR-based metabolomics: quality and authenticity of plant-based foods

Nowadays metabolomics is a widely accepted approach in several scientific disciplines, especially in food science. The possibility to identify a wide range of metabolites (untargeted analysis) allowed to evaluate various food characteristics, regarding quality, adulteration, geographical origin, as well as secondary species-specific metabolites endowed with nutraceutical properties. In the present chapter, latest findings of plant-based foods investigated by NMR-based metabolomics are presented. Almost all of the recent studies were focused on quality assessment and authenticity; different aspects such as geographical origin, metabolic modifications upon stress, nutraceutical properties, and fraud detection are described as well. The here reported plant-based foods are balsamic and traditional balsamic vinegars, cereals, cocoa, coffee, fruits, legumes, spices, vegetables and vegetable oils, wine, beer, and spirits. A brief paragraph is concerning organic and conventional foods, which is a new growing scientific field of interest for researchers encouraged by the increasing consumers’ demand. The results here reported testify the capability and the power of this approach thus endorsing NMR spectroscopy as a valid alternative or complement to the chemical and physical analysis nowadays routinely applied for the quality assessment