Remodeling Of Membrane Phospholipids Research Articles

Genomic and phenotypic characterization of 26 novel marine bacterial strains with relevant biogeochemical roles and widespread presence across the global ocean.

Prokaryotes dominate global oceans and shape biogeochemical cycles, yet most taxa remain uncultured and uncharacterized as of today. Here we present the characterization of 26 novel marine bacterial strains from a large isolate collection obtained from Blanes Bay (NW Mediterranean) microcosm experiments made in the four seasons. Morphological, cultural, biochemical, physiological, nutritional, genomic, and phylogenomic analyses were used to characterize and phylogenetically place the novel isolates. The strains represent 23 novel bacterial species and six novel genera: three novel species pertaining to class Alphaproteobacteria (families Rhodobacteraceae and Sphingomonadaceae), six novel species and three new genera from class Gammaproteobacteria (families Algiphilaceae, Salinispheraceae, and Alteromonadaceae), 13 novel species and three novel genera from class Bacteroidia (family Flavobacteriaceae), and one new species from class Rhodothermia (family Rubricoccaceae). The bacteria described here have potentially relevant roles in the cycles of carbon (e.g., carbon fixation or energy production via proteorhodopsin), nitrogen (e.g., denitrification or use of urea), sulfur (oxidation of sulfur compounds), phosphorus (acquisition and use of different forms of phosphorus and remodeling of membrane phospholipids), and hydrogen (oxidation of hydrogen to obtain energy). We mapped the genomes of the presented strains to the Tara Oceans metagenomes to reveal that these strains were globally distributed, with those of the family Flavobacteriaceae being the most widespread and abundant, while Rhodothermia being the rarest and most localized. While molecular-only approaches are also important, our study stresses the importance of culturing as a powerful tool to further understand the functioning of marine bacterial communities.

ACSL4-Mediated Membrane Phospholipid Remodeling Induces Integrin β1 Activation to Facilitate Triple-Negative Breast Cancer Metastasis.

ACSL4 upregulation in triple-negative breast cancer alters cell membrane phospholipid composition to increase integrin β1 activation and drive metastasis, indicating that targeting ACSL4 could potentially block metastasis and improve patient outcomes.

Membrane lipid remodeling and autophagy to cope with phosphorus deficiency in the dinoflagellate Prorocentrum shikokuense

Dinoflagellates, which are responsible for more than 80% of harmful algal blooms in coastal waters, are competitive in low-phosphate environments. However, the specific acclimated phosphorus strategies to adapt to phosphorus deficiency in dinoflagellates, particularly through intracellular phosphorus metabolism, remain largely unknown. Comprehensive physiological, biochemical, and transcriptomic analyses were conducted to investigate intracellular phosphorus modulation in a model dinoflagellate, Prorocentrum shikokuense, with a specific focus on membrane lipid remodeling and autophagy in response to phosphorus deficiency. Under phosphorus deficiency, P. shikokuense exhibited a preference to spare phospholipids with nonphospholipids. The major phospholipid classes of phosphatidylcholine and phosphatidylethanolamine decreased in content, whereas the betaine lipid class of diacylglyceryl carboxyhydroxymethylcholine increased in content. Furthermore, under phosphorus deficiency, P. shikokuense induced autophagy as a mechanism to conserve and recycle cellular phosphorus resources. The present study highlights the effective modulation of intracellular phosphorus in P. shikokuense through membrane phospholipid remodeling and autophagy and contributes to a comprehensive understanding of the acclimation strategies to low-phosphorus conditions in dinoflagellates.

Efficient modulation of cellular phosphorus components in response to phosphorus deficiency in the dinoflagellate Karenia mikimotoi.

Dinoflagellates are the most common phytoplankton group and account for more than 75% of harmful algal blooms in coastal waters. In recent decades, dinoflagellates seem to prevail in phosphate-depleted waters. However, the underlying acclimation mechanisms and competitive strategies of dinoflagellates in response to phosphorus deficiency are poorly understood, especially in terms of intracellular phosphorus modulation and recycling. Here, we focused on the response of intracellular phosphorus metabolism to phosphorus deficiency in the model dinoflagellate Karenia mikimotoi. Our work reveals the strong capability of K. mikimotoi to efficiently regulate intracellular phosphorus resources, particularly through membrane phospholipid remodeling and miRNA regulation of energy metabolism. Our research improved the understanding of intracellular phosphorus metabolism in marine phytoplankton and underscored the advantageous strategies of dinoflagellates in the efficient modulation of internal phosphorus resources to maintain active physiological activity and growth under unsuitable phosphorus conditions, which help them outcompete other species in coastal phosphate-depleted environments.

Membrane phospholipid remodeling modulates nonalcoholic steatohepatitis progression by regulating mitochondrial homeostasis.

NASH, characterized by inflammation and fibrosis, is emerging as a leading etiology of HCC. Lipidomics analyses in the liver have shown that the levels of polyunsaturated phosphatidylcholine (PC) are decreased in patients with NASH, but the roles of membrane PC composition in the pathogenesis of NASH have not been investigated. Lysophosphatidylcholine acyltransferase 3 (LPCAT3), a phospholipid (PL) remodeling enzyme that produces polyunsaturated PLs, is a major determinant of membrane PC content in the liver. The expression of LPCAT3 and the correlation between its expression and NASH severity were analyzed in human patient samples. We examined the effect of Lpcat3 deficiency on NASH progression using Lpcat3 liver-specific knockout (LKO) mice. RNA sequencing, lipidomics, and metabolomics were performed in liver samples. Primary hepatocytes and hepatic cell lines were used for in vitro analyses. We showed that LPCAT3 was dramatically suppressed in human NASH livers, and its expression was inversely correlated with NAFLD activity score and fibrosis stage. Loss of Lpcat3 in mouse liver promotes both spontaneous and diet-induced NASH/HCC. Mechanistically, Lpcat3 deficiency enhances reactive oxygen species production due to impaired mitochondrial homeostasis. Loss of Lpcat3 increases inner mitochondrial membrane PL saturation and elevates stress-induced autophagy, resulting in reduced mitochondrial content and increased fragmentation. Furthermore, overexpression of Lpcat3 in the liver ameliorates inflammation and fibrosis of NASH. These results demonstrate that membrane PL composition modulates the progression of NASH and that manipulating LPCAT3 expression could be an effective therapeutic for NASH.

Use of Elamipretide in patients assigned treatment in the compassionate use program: Case series in pediatric patients with rare orphan diseases.

Several mitochondrial diseases are caused by pathogenic variants that impair membrane phospholipid remodeling, with no FDA-approved therapies. Elamipretide targets the inner mitochondrial membrane where it binds to cardiolipin, resulting in improved membrane stability, cellular respiration, and ATP production. In clinical trials, elamipretide produced clinical and functional improvements in adults and adolescents with mitochondrial disorders, such as primary mitochondrial myopathy and Barth syndrome; however, experience in younger patients is limited and to our knowledge, these are the first case reports on the safety and efficacy of elamipretide treatment in children under 12 years of age. We describe the use of elamipretide in patients with mitochondrial disorders to provide dosing parameters in patients aged <12 years.

PLRP2 selectively localizes synaptic membrane proteins via acyl-chain remodeling of phospholipids

The plasma membrane of neurons consists of distinct domains, each of which carries specialized functions and a characteristic set of membrane proteins. While this compartmentalized membrane organization is essential for neuronal functions, it remains controversial how neurons establish these domains on the laterally fluid membrane. Here, using immunostaining, lipid-MS analysis and gene ablation with the CRISPR/Cas9 system, we report that the pancreatic lipase-related protein 2 (PLRP2), a phospholipase A1 (PLA1), is a key organizer of membrane protein localization at the neurite tips of PC12 cells. PLRP2 produced local distribution of 1-oleoyl-2-palmitoyl-PC at these sites through acyl-chain remodeling of membrane phospholipids. The resulting lipid domain assembled the syntaxin 4 (Stx4) protein within itself by selectively interacting with the transmembrane domain of Stx4. The localized Stx4, in turn, facilitated the fusion of transport vesicles that contained the dopamine transporter with the domain of the plasma membrane, which led to the localized distribution of the transporter to that domain. These results revealed the pivotal roles of PLA1, specifically PLRP2, in the formation of functional domains in the plasma membrane of neurons. In addition, our results suggest a mode of membrane organization in which the local acyl-chain remodeling of membrane phospholipids controls the selective localization of membrane proteins by regulating both lipid-protein interactions and the fusion of transport vesicles to the lipid domain.

Microvésicules : biomarqueurs non invasifs de l’endothélium

The endothelium is recognized today as a tissue of great plasticity, able to remodel itself in response to cellular activation or injury. The identification of circulating endothelial cells and microvesicles (MVE) in the peripheral blood has open the way to new non-invasive explorative methods that fall under the concept of “liquid biopsy of the endothelium”. MV are subcellular elements resulting from the remodeling of membrane phospholipids in response to cellular activation or apoptosis. They are known as vectors of biological information participating in intercellular communication and involved in many physiopathological processes. The progress made in recent years on the control of preanalytical conditions and the development of sensitive techniques measuring the number and the functional activity of MV have accelerated their transfer to the clinic. The increase of their plasma levels is correlated to cardiovascular risk factors and endothelial dysfunction. These increase has been reported in vascular pathologies in which they represent promising biomarkers to predict the vascular risk. Large-scale multicenter studies and the integration of EMV into clinic-biological scores remain necessary in order to better define their relevance in clinical practice.

Phospholipid synthetic and turnover pathways elicited upon exposure to different xenobiotics

Phospholipids, neutral lipids and glycolipids metabolism take the place during cell responses to different stimuli. Phospholipase and acyl glycerol lipase activities have been demonstrated to release second messengers that trigger cascade responses. Studies on lipid droplets structure, formation and interaction with other organelles have recently been described in prokaryotes and eukaryotes. Remodeling of membrane phospholipids has also been reported. NMR studies performed on synthetic membranes allowed to postulate membrane lipids polymorphism and to explain how processes like cell division, endocytosis and exocytosis can take place, due to special arrangements of the membranes. Studies from our research group on the pesticide dieldrin and Cu2+ effects through exposure of amphibian oocytes and embryos to sub-lethal and acclimation concentrations followed by toxic concentration challenges respectively, are discussed. Membrane phospholipids structure alterations allowing stabilization of bilayer arrangements were found for both stressors in cell and tissues. Metallothionein induction response that prevents oxidative stress was also found in acclimated embryo tissues. Probable connections between enzyme activities taking place on lysophospholipid and triacylglycerol substrates present in lipid droplets as well as phospholipid trafficking leading to modifications on membrane phospholipid ratios are discussed. Current new evidences in agreement with our findings allow us to suggest that our previously published results of dieldrin effects on amphibian cells correspond to joint coordinated activities, which probably had involved various metabolic pathways, in line with the acclimation experiment results and discussion. Independently of the cascade responses each toxicant is able to elicit, lipids play an important role in cell responses, both through rapid turnover and final stabilization of membrane bilayers.

Membrane Allostery and Hydrophobic Binding Sites Control Substrate Specificity of Lipolytic Enzymes

Connecting molecular structure with cellular function is fundamental to understanding the mechanism of action of water‐soluble enzymes acting on cell membranes (PNAS 2015, 112, E516–E525). Cytosolic (cPLA2), calcium‐independent (iPLA2) and lipoprotein‐associated (Lp‐PLA2) provide an ideal system for studying protein‐lipid molecular recognition and membrane functioning. cPLA2 is the main arachidonic acid provider for the eicosanoid pathway, iPLA2 is involved in membrane phospholipid remodeling and Lp‐PLA2 was found to associate with LDL and HDL in human plasma to hydrolyze phospholipids containing short‐chain and oxidized fatty acids. A lipidomics mass spectrometric assay allowed us to define unique specificity of PLA2s towards a wide variety of phospholipids that was not feasible with existing assays. Computational techniques such as molecular dynamics simulations and docking guided by hydrogen/deuterium (H/D) exchange experimental data showed that membrane phospholipids bind to allosteric sites located on the interfacial surface of PLA2s, shifting their conformation from the “closed” to the “open” state. This process enables PLA2s to extract and bind a phospholipid molecule in the active site where the hydrolysis occurs. This is a novel study addressing recognition between water‐soluble enzymes and membranes as well as substrate specificity, binding and interactions using computational techniques guided by experimental data. PLA2s are implicated in chronic inflammatory diseases and understanding their association with membranes as well as their interactions with substrates will allow us to identify potent and selective inhibitors that can be further developed as anti‐inflammatory agents (J. Med. Chem. 2016, 59, 4403–4414).Support or Funding InformationNIH grant GM20501‐41This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Intestinal CD36 and Other Key Proteins of Lipid Utilization: Role in Absorption and Gut Homeostasis.

Several proteins have been implicated in fatty acid (FA) transport by enterocytes including the scavenger receptor CD36 (SR-B2), the scavenger receptor B1 (SR-B1) a member of the CD36 family and the FA transport protein 4 (FATP4). Here, we review the regulation of enterocyte FA uptake and its function in lipid absorption including prechylomicron formation, assembly and transport. Emphasis is given to CD36, which is abundantly expressed along the digestive tract of rodents and humans and has been the most studied. We also address the pleiotropic functions of CD36 that go beyond lipid absorption and metabolism to include recent evidence of its impact on intestinal homeostasis and barrier maintenance. Areas of progress involving contribution of membrane phospholipid remodeling and of cytosolic FA-binding proteins, FABP1 and FABP2 to fat absorption will be covered. © 2018 American Physiological Society. Compr Physiol 8:493-507, 2018.

Phospholipid Remodeling and Cholesterol Availability Regulate Intestinal Stemness and Tumorigenesis.

Adequate availability of cellular building blocks, including lipids, is a prerequisite for cellular proliferation, but excess dietary lipids are linked to increased cancer risk. Despite these connections, specific regulatory relationships between membrane composition, intestinal stem cell (ISC) proliferation, and tumorigenesis are unclear. We reveal an unexpected link between membrane phospholipid remodeling and cholesterol biosynthesis and demonstrate that cholesterol itself acts as a mitogen forISCs. Inhibition of the phospholipid-remodeling enzyme Lpcat3 increases membrane saturation and stimulates cholesterol biosynthesis, thereby driving ISC proliferation. Pharmacologic inhibition of cholesterol synthesis normalizes crypt hyperproliferation in Lpcat3-deficient organoids and mice. Conversely, increasing cellular cholesterol content stimulates crypt organoid growth, and providing excess dietary cholesterol or driving endogenous cholesterol synthesis through SREBP-2 expression promotes ISC proliferation invivo. Finally, disruption of Lpcat3-dependent phospholipid and cholesterol homeostasis dramatically enhances tumor formation in Apcmin mice. These findings identify a critical dietary-responsive phospholipid-cholesterol axis regulating ISC proliferation and tumorigenesis.

OP-33 - Lipid peroxidation, lipohormesis and lipotoxicity in diabetes

Little is known about the impact of lipids, phospholipid turnover and metabolism within membranes of insulin granules in pancreatic beta cells. We have discovered that high levels of glucose and saturated fatty acids affect glucose-stimulated insulin secretion and cell viability in a biphasic manner: non-cytotoxic levels of both induce a hormetic response that augments insulin secretion, which increases the rate of glucose and fatty acids disposal from the circulation to storage organs. This hormetic response is lost at very high levels of both nutrients, which synergistically attenuate insulin secretion and progressively causes apoptotic beta cell death. These hormetic and detrimental processes are tightly linked to membrane phospholipid remodeling and enhanced lipid peroxidation. The basis of these interactions includes enzymatic and non-enzymatic metabolism of polyunsaturated fatty acids and the emergence of hormetic mediators (e.g., 4‑hydroxynonenal) that act at low levels as activating ligands of PPARδ and as cytotoxic agents at high levels. In addition, monounsaturated fatty acids protect beta cells by enhancing the incorporation of saturated fatty acids into triglycerides and their sequestration in newly formed lipid droplets.

FGF21-FGFR1 Coordinates Phospholipid Homeostasis, Lipid Droplet Function, and ER Stress in Obesity.

The antiobese and antidiabetic fibroblast growth factor 21 (FGF21) regulates lipid metabolism and energy homeostasis by targeting the βKlotho-FGFR1 (fibroblast growth factor receptor 1) binary complex in adipose tissue adipocytes. Because lipid droplet is the organelle responsible for storing lipid energy in adipocytes, it is the plausible target of FGF21 action. However, the impact of the FGF21-βKlotho-FGFR1 signaling pathway on the functions of the lipid droplet is not clearly understood. Using our mouse models of adipocyte-specific FGFR1 ablation and hepatic overexpression of FGF21 with diet-induced obesity established previously, we analyzed the alterations of the pathways involved in energy and substrate metabolism that is attributable to the dynamic functions of the lipid droplet. In addition to the previous reports showing that FGFR1 deficiency abrogated lipolysis, fatty acid oxidation, and energy expenditure promoted by the elevated FGF21 signal, we observed that the deficiency up-regulated the biosynthesis and remodeling of membrane phospholipids that are important for the biogenesis and expansion of the droplet, whereas the enhanced FGF21 signal constrained the biosynthesis of phospholipids. As a result, the loss of adipose FGFR1 led to a sustained droplet expansion and endoplasmic reticulum (ER) stress, whereas the enhanced FGF21 signal suppressed them in obesogenesis. These new findings reveal that the FGF21-βKlotho-FGFR1 signaling axis plays roles in maintaining phospholipid homeostasis and the dynamic functions of the lipid droplet, whereas protecting against ER stress, and suggest a potential link of phospholipid biosynthesis, lipid droplet dynamics, ER stress, and energy homeostasis in adipose tissue coordinated by this signaling axis.

Synthetic cell membranes remodeled chemically

Researchers have developed a way to chemically remodel synthetic cell membranes, similar to the way enzymes remodel mammalian cell membranes in living cells. In biological cells, the remodeling of membrane phospholipids by enzymes such as acyltransferases and transacylases plays a key role in many cell functions, such as division, membrane transport, and cell signaling. Synthetic membranes have been developed as stand-ins for studying these processes in native membranes, but researchers have not been able to mimic membrane remodeling. Neal K. Devaraj and coworkers at the University of California, San Diego, now report the use of chemical reactions to remodel phospholipids in synthetic membranes (Proc. Natl. Acad. Sci. USA 2016, DOI: 10.1073/pnas.1605541113). Each phospholipid contains a head group and a lipid acyl chain. The researchers reported earlier that native chemical ligation can combine head groups and lipid chains to create new phospholipids that assemble into synthetic membranes. They now show that

Substrate selectivity of Lysophospholipid Transporter LplT Involved in Membrane Phospholipid Remodeling in Escherichia coli

Lysophospholipid transporter (LplT) was previously found to be primarily involved in 2‐ acyl lyso‐PE recycling in gram‐negative bacterium. This work identified the potent role of LplT in maintaining membrane stability and integrity in E.coli envelope. We demonstrated the involvement of LplT in the recycling of three major bacterial phospholipids by using combination of in vitro lysophospholipid binding assay with purified protein and transport assays with E.coli spheroplasts. Our results showed that lyso‐PE and lyso‐PG, but not lyso‐PC, were taken up by LplT for reacylation by acyltransferase/acylACP synthetase (Aas) on the inner leaflet of the membrane. We also found a novel cardiolipin hydrolysis reaction by phospholipase A2 to form diacylated cardiolipin and eventually the completely deacylated head group. These two distinct cardiolipin derivatives were both translocated with comparable efficiency to generate tri‐acylated cardiolipin by Aas, demonstrating the first evidence of cardiolipin remodeling in bacterium and supporting a notion that fatty acid chain is not required for LplT transport. We also found that LplT cannot transport lyso‐PA and its substrate binding was not inhibited by either orthophosphate or glycerol‐3‐ phosphate, revealing that glycerol or ethanolamine head group is the chemical determinant for substrate recognition. Any diacyl form of PE, PG or tetra‐acylated form of cardiolipin could not serve as competitive inhibitors in vitro. Based on an evolutionary structural model, a proposed “sideways sliding” mechanism explains how a conserved membrane‐embedded α‐helical interface excludes diacylphospholipids from the LplT binding site to facilitate efficient flipping of lysophosholipid across the cell membrane.Support or Funding InformationThis work was supported by NIH grant R01 to Lei Zheng.

Substrate Selectivity of Lysophospholipid Transporter LplT Involved in Membrane Phospholipid Remodeling in Escherichia coli

Lysophospholipid transporter (LplT) was previously found to be primarily involved in 2-acyl lysophosphatidylethanolamine (lyso-PE) recycling in Gram-negative bacteria. This work identifies the potent role of LplT in maintaining membrane stability and integrity in the Escherichia coli envelope. Here we demonstrate the involvement of LplT in the recycling of three major bacterial phospholipids using a combination of an in vitro lysophospholipid binding assay using purified protein and transport assays with E. coli spheroplasts. Our results show that lyso-PE and lysophosphatidylglycerol, but not lysophosphatidylcholine, are taken up by LplT for reacylation by acyltransferase/acyl-acyl carrier protein synthetase on the inner leaflet of the membrane. We also found a novel cardiolipin hydrolysis reaction by phospholipase A2 to form diacylated cardiolipin progressing to the completely deacylated headgroup. These two distinct cardiolipin derivatives were both translocated with comparable efficiency to generate triacylated cardiolipin by acyltransferase/acyl-acyl carrier protein synthetase, demonstrating the first evidence of cardiolipin remodeling in bacteria. These findings support that a fatty acid chain is not required for LplT transport. We found that LplT cannot transport lysophosphatidic acid, and its substrate binding was not inhibited by either orthophosphate or glycerol 3-phosphate, indicating that either a glycerol or ethanolamine headgroup is the chemical determinant for substrate recognition. Diacyl forms of PE, phosphatidylglycerol, or the tetra-acylated form of cardiolipin could not serve as a competitive inhibitor in vitro. Based on an evolutionary structural model, we propose a “sideways sliding” mechanism to explain how a conserved membrane-embedded α-helical interface excludes diacylphospholipids from the LplT binding site to facilitate efficient flipping of lysophospholipid across the cell membrane.

Role of aminoalcoholphosphotransferases 1 and 2 in phospholipid homeostasis in Arabidopsis.

Aminoalcoholphosphotransferase (AAPT) catalyzes the synthesis of phosphatidylcholine (PC) and phosphotidylethanolamine (PE), which are the most prevalent membrane phospholipids in all eukaryotic cells. Here, we show that suppression of AAPTs results in extensive membrane phospholipid remodeling in Arabidopsis thaliana. Double knockout (KO) mutants that are hemizygous for either aapt1 or aapt2 display impaired pollen and seed development, leading to embryotic lethality of the double KO plants, whereas aapt1 or aapt2 single KO plants show no overt phenotypic alterations. The growth rate and seed yield of AAPT RNA interference (RNAi) plants are greatly reduced. Lipid profiling shows decreased total galactolipid and phospholipid content in aapt1-containing mutants, including aapt1, aapt1/aapt1 aapt2/AAPT2, aapt1/AAPT1 aapt2/aapt2, and AAPT RNAi plants. The level of PC in leaves was unchanged, whereas that of PE was reduced in all AAPT-deficient plants, except aapt2 KO. However, the acyl species of PC was altered, with increased levels of C34 species and decreased C36 species. Conversely, the levels of PE and phosphatidylinositol were decreased in C34 species. In seeds, all AAPT-deficient plants, including aapt2 KO, displayed a decrease in PE. The data show that AAPT1 and AAPT2 are essential to plant vegetative growth and reproduction and have overlapping functions but that AAPT1 contributes more than AAPT2 to PC production in vegetative tissues. The opposite changes in molecular species between PC and PE and unchanged PC level indicate the existence of additional pathways that maintain homeostatic levels of PC, which are crucial for the survival and proper development of plants.

Mitochondria: A crossroads for lipid metabolism defect in neurodegeneration with brain iron accumulation diseases

Neurodegeneration with brain iron accumulation (NBIA) comprises a group of brain iron deposition syndromes that lead to mixed extrapyramidal features and progressive dementia. Exact pathologic mechanism of iron deposition in NBIA remains unknown. However, it is becoming increasingly evident that many neurodegenerative diseases are hallmarked by metabolic dysfunction that often involves altered lipid profile. Among the identified disease genes, four encode for proteins localized in mitochondria, which are directly or indirectly implicated in lipid metabolism: PANK2, CoASY, PLA2G6 and C19orf12. Mutations in PANK2 and CoASY, both implicated in CoA biosynthesis that acts as a fatty acyl carrier, lead, respectively, to PKAN and CoPAN forms of NBIA. Mutations in PLA2G6, which plays a key role in the biosynthesis and remodeling of membrane phospholipids including cardiolipin, lead to PLAN. Mutations in C19orf12 lead to MPAN, a syndrome similar to that caused by mutations in PANK2 and PLA2G6. Although the function of C19orf12 is largely unknown, experimental data suggest its implication in mitochondrial homeostasis and lipid metabolism. Altogether, the identified mutated proteins localized in mitochondria and associated with different NBIA forms support the concept that dysfunctions in mitochondria and lipid metabolism play a crucial role in the pathogenesis of NBIA.This article is part of a Directed Issue entitled: Energy Metabolism Disorders and Therapies.

Pre-analytical issues in the measurement of circulating microparticles: current recommendations and pending questions

Pre-analytical issues in the measurement of circulating microparticles: current recommendations and pending questions