The synaptic lipidome in health and disease

Glia-derived secretory fatty acid binding protein Obp44a regulates lipid storage and efflux in the developing Drosophila brain

Glia derived secretory factors play diverse roles in supporting the development, physiology, and stress responses of the central nervous system (CNS). Through transcriptomics and imaging analyses, we have identified Obp44a as one of the most abundantly produced secretory proteins from Drosophila CNS glia. Protein structure homology modeling and Nuclear Magnetic Resonance (NMR) experiments reveal Obp44a as a fatty acid binding protein (FABP) with a high affinity towards long-chain fatty acids in both native and oxidized forms. Further analyses demonstrate that Obp44a effectively infiltrates the neuropil, traffics between neuron and glia, and is secreted into hemolymph, acting as a lipid chaperone and scavenger to regulate lipid and redox homeostasis in the developing brain. In agreement with this essential role, deficiency of Obp44a leads to anatomical and behavioral deficits in adult animals and elevated oxidized lipid levels. Collectively, our findings unveil the crucial involvement of a noncanonical lipid chaperone to shuttle fatty acids within and outside the brain, as needed to maintain a healthy brain lipid environment. These findings could inspire the design of novel approaches to restore lipid homeostasis that is dysregulated in CNS diseases.

Molecular and biophysical features of hippocampal "lipid rafts aging" are modified by dietary n-3 long-chain polyunsaturated fatty acids

"Lipid raft aging" in nerve cells represents an early event in the development of aging-related neurodegenerative diseases, such as Alzheimer's disease. Lipid rafts are key elements in synaptic plasticity, and their modification with aging alters interactions and distribution of signaling molecules, such as glutamate receptors and ion channels involved in memory formation, eventually leading to cognitive decline. In the present study, we have analyzed, in vivo, the effects of dietary supplementation of n-3 LCPUFA on the lipid structure, membrane microviscosity, domain organization, and partitioning of ionotropic and metabotropic glutamate receptors in hippocampal lipid raffs in female mice. The results revealed several lipid signatures of "lipid rafts aging" in old mice fed control diets, consisting in depletion of n-3 LCPUFA, membrane unsaturation, along with increased levels of saturates, plasmalogens, and sterol esters, as well as altered lipid relevant indexes. These changes were paralleled by increased microviscosity and changes in the raft/non-raft (R/NR) distribution of AMPA-R and mGluR5. Administration of the n-3 LCPUFA diet caused the partial reversion of fatty acid alterations found in aged mice and returned membrane microviscosity to values found in young animals. Paralleling these findings, lipid rafts accumulated mGluR5, NMDA-R, and ASIC2, and increased their R/NR proportions, which collectively indicate changes in synaptic plasticity. Unexpectedly, this diet also modified the lipidome and dimension of lipid rafts, as well as the domain redistribution of glutamate receptors and acid-sensing ion channels involved in hippocampal synaptic plasticity, likely modulating functionality of lipid rafts in memory formation and reluctance to age-associated cognitive decline.

Lysophospholipids: A Potential Drug Candidates for Neurodegenerative Disorders

Neurodegenerative diseases (NDs) commonly present misfolded and aggregated proteins. Considerable research has been performed to unearth the molecular processes underpinning this pathological aggregation and develop therapeutic strategies targeting NDs. Fibrillary deposits of α-synuclein (α-Syn), a highly conserved and thermostable protein, are a critical feature in the development of NDs such as Alzheimer's disease (AD), Lewy body disease (LBD), Parkinson's disease (PD), and multiple system atrophy (MSA). Inhibition of α-Syn aggregation can thus serve as a potential approach for therapeutic intervention. Recently, the degradation of target proteins by small molecules has emerged as a new therapeutic modality, gaining the hotspot in pharmaceutical research. Additionally, interest is growing in the use of food-derived bioactive compounds as intervention agents against NDs via functional foods and dietary supplements. According to reports, dietary bioactive phospholipids may have cognition-enhancing and neuroprotective effects, owing to their abilities to influence cognition and mental health in vivo and in vitro. However, the mechanisms by which lipids may prevent the pathological aggregation of α-Syn warrant further clarification. Here, we review evidence for the potential mechanisms underlying this effect, with a particular focus on how porcine liver decomposition product (PLDP)-derived lysophospholipids (LPLs) may inhibit α-Syn aggregation.