Multiple Timescale Dynamic Analysis of Functionally-Impairing Mutations in Human Ileal Bile Acid-Binding Protein.

Human ileal bile acid-binding protein (hI-BABP) has a key role in the enterohepatic circulation of bile salts. Its two internal binding sites exhibit positive cooperativity accompanied by a site-selectivity of glycocholate (GCA) and glycochenodeoxycholate (GCDA), the two most abundant bile salts in humans. To improve our understanding of the role of dynamics in ligand binding, we introduced functionally impairing single-residue mutations at two key regions of the protein and subjected the mutants to NMR relaxation analysis and MD simulations.

Reverse and Forward Electron Flow-Induced HO Formation Is Decreased in α-Ketoglutarate Dehydrogenase (α-KGDH) Subunit (E2 or E3) Heterozygote Knock Out Animals.

α-ketoglutarate dehydrogenase complex (KGDHc), or 2-oxoglutarate dehydrogenase complex (OGDHc) is a rate-limiting enzyme in the tricarboxylic acid cycle, that has been identified in neurodegenerative diseases such as in Alzheimer's disease. The aim of the present study was to establish the role of the KGDHc and its subunits in the bioenergetics and reactive oxygen species (ROS) homeostasis of brain mitochondria. To study the bioenergetic profile of KGDHc, genetically modified mouse strains were used having a heterozygous knock out (KO) either in the dihydrolipoyl succinyltransferase (DLST) or in the dihydrolipoyl dehydrogenase (DLD) subunit.

The effect of Cyclophilin D depletion on liver regeneration following associating liver partition and portal vein ligation for staged hepatectomy.

Aim: Associating Liver Partition and Portal vein ligation for Staged hepatectomy (ALPPS) is a modification of two-stage hepatectomy profitable for patients with inoperable hepatic tumors by standard techniques. Unfortunately, initially poor postoperative outcome was associated with ALPPS, in which mitochondrial dysfunction played an essential role. Inhibition of cyclophilins has been already proposed to be efficient as a mitochondrial therapy in liver diseases.

The effects of physical prehabilitation: Improved liver regeneration and mitochondrial function after ALPPS operation in a rodent model.

Background: To identify the role of physical prehabilitation (PP) in liver regeneration, mitochondrial function, biogenesis, and inflammatory response was investigated after associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) in a rodent model.

Methods: Male Wistar rats (n = 60) underwent ALPPS. Animals were divided (n = 30) to the physical prehabilitation group (PP) and sedentary group (S).

Bioenergetic Impairment of Triethylene Glycol Dimethacrylate- (TEGDMA-) Treated Dental Pulp Stem Cells (DPSCs) and Isolated Brain Mitochondria are Amended by Redox Compound Methylene Blue .

Background: Triethylene glycol dimethacrylate (TEGDMA) monomers released from resin matrix are toxic to dental pulp cells, induce apoptosis, oxidative stress and decrease viability. Recently, mitochondrial complex I (CI) was identified as a potential target of TEGDMA. In isolated mitochondria supported by CI, substrates oxidation and ATP synthesis were inhibited, reactive oxygen species production was stimulated.

Novel mitochondrial transition pore inhibitor N-methyl-4-isoleucine cyclosporin is a new therapeutic option in acute pancreatitis.

Key Points: •Bile acids, ethanol and fatty acids affect pancreatic ductal fluid and bicarbonate secretion via mitochondrial damage, ATP depletion and calcium overload. •Pancreatitis-inducing factors open the membrane transition pore (mPTP) channel via cyclophilin D activation in acinar cells, causing calcium overload and cell death; genetic or pharmacological inhibition of mPTP improves the outcome of acute pancreatitis in animal models. •Here we show that genetic and pharmacological inhibition of mPTP protects mitochondrial homeostasis and cell function evoked by pancreatitis-inducing factors in pancreatic ductal cells.

Ligand entry in human ileal bile acid-binding protein is mediated by histidine protonation.

Human ileal bile acid-binding protein (hI-BABP) has a key role in the intracellular transport of bile salts. To explore the role of histidine protonation in the binding process, the pH-dependence of bile salt binding and internal dynamics in hI-BABP was investigated using NMR spectroscopy and biophysical tools. Thermodynamic and kinetic measurements show an increase in the overall binding affinity and the association rate constant of the first binding step below the pK of the histidines, suggesting that ligand binding is favoured by the protonated state.

Mutated SUCLG1 causes mislocalization of SUCLG2 protein, morphological alterations of mitochondria and an early-onset severe neurometabolic disorder.

Succinate-CoA ligase (SUCL) is a heterodimer consisting of an alpha subunit encoded by SUCLG1, and a beta subunit encoded by either SUCLA2 or SUCLG2 catalyzing an ATP- or GTP-forming reaction, respectively, in the mitochondrial matrix. The deficiency of this enzyme represents an encephalomyopathic form of mtDNA depletion syndromes. We describe the fatal clinical course of a female patient with a pathogenic mutation in SUCLG1 (c.

GABA, glutamine, glutamate oxidation and succinic semialdehyde dehydrogenase expression in human gliomas.

Background: Bioenergetic characterisation of malignant tissues revealed that different tumour cells can catabolise multiple substrates as salvage pathways, in response to metabolic stress. Altered metabolism in gliomas has received a lot of attention, especially in relation to IDH mutations, and the associated oncometabolite D-2-hydroxyglutarate (2-HG) that impact on metabolism, epigenetics and redox status. Astrocytomas and oligodendrogliomas, collectively called diffuse gliomas, are derived from astrocytes and oligodendrocytes that are in metabolic symbiosis with neurons; astrocytes can catabolise neuron-derived glutamate and gamma-aminobutyric acid (GABA) for supporting and regulating neuronal functions.

Evaluation of mitochondrial function in chronic myofascial trigger points - a prospective cohort pilot study using high-resolution respirometry.

Background: Myofascial trigger points (MTrPs) are hyperirritable areas in the fascia of the affected muscle, possibly related to mitochondrial impairment. They can result in pain and hypoxic areas within the muscle. This pilot study established a minimally invasive biopsy technique to obtain high-quality MTrP tissue samples to evaluate mitochondrial function via high-resolution respirometry.

Triethylene glycol dimethacrylate impairs bioenergetic functions and induces oxidative stress in mitochondria via inhibiting respiratory Complex I.

Objectives: Earlier studies demonstrated that dental resin monomers lower cellular viability and provoke oxidative stress. Reactive oxygen species (ROS) formation has a key role in triethylene glycol dimethacrylate (TEGDMA) induced adverse reactions. In the present study the effects of TEGDMA on mitochondrial functions were investigated to identify a direct molecular target for cytotoxicity.

Versatility of microglial bioenergetic machinery under starving conditions.

Microglia are highly dynamic cells in the brain. Their functional diversity and phenotypic versatility brought microglial energy metabolism into the focus of research. Although it is known that microenvironmental cues shape microglial phenotype, their bioenergetic response to local nutrient availability remains unclear.

Structural insight into a partially unfolded state preceding aggregation in an intracellular lipid-binding protein.

Human ileal bile acid-binding protein (I-BABP) has a key role in the intracellular transport and metabolic targeting of bile salts. Similar to other members of the family of intracellular lipid-binding proteins (iLBPs), disorder-order transitions and local unfolding processes are thought to mediate ligand entry and release in human I-BABP. To gain insight into the stability of various protein regions, the temperature response of human I-BABP was investigated using NMR, CD and fluorescence spectroscopy, as well as molecular dynamics (MD) simulations.

TP53 mutation hits energy metabolism and increases glycolysis in breast cancer.

Promising new hallmarks of cancer is alteration of energy metabolism that involves molecular mechanisms shifting cancer cells to aerobe glycolysis. Our goal was to evaluate the correlation between mutation in the commonly mutated tumor suppressor gene TP53 and metabolism. We established a database comprising mutation and RNA-seq expression data of the TCGA repository and performed receiver operating characteristics (ROC) analysis to compare expression of each gene between TP53 mutated and wild type samples.

Structural determinants of ligand binding in the ternary complex of human ileal bile acid binding protein with glycocholate and glycochenodeoxycholate obtained from solution NMR.

Unlabelled: Besides aiding digestion, bile salts are important signal molecules exhibiting a regulatory role in metabolic processes. Human ileal bile acid binding protein (I-BABP) is an intracellular carrier of bile salts in the epithelial cells of the distal small intestine and has a key role in the enterohepatic circulation of bile salts. Positive binding cooperativity combined with site selectivity of glycocholate and glycochenodeoxycholate, the two most abundant bile salts in the human body, make human I-BABP a unique member of the family of intracellular lipid binding proteins.

Abolition of mitochondrial substrate-level phosphorylation by itaconic acid produced by LPS-induced Irg1 expression in cells of murine macrophage lineage.

Itaconate is a nonamino organic acid exhibiting antimicrobial effects. It has been recently identified in cells of macrophage lineage as a product of an enzyme encoded by immunoresponsive gene 1 (Irg1), acting on the citric acid cycle intermediate cis-aconitate. In mitochondria, itaconate can be converted by succinate-coenzyme A (CoA) ligase to itaconyl-CoA at the expense of ATP (or GTP), and is also a weak competitive inhibitor of complex II.

Temperature dependence of backbone dynamics in human ileal bile acid-binding protein: implications for the mechanism of ligand binding.

Human ileal bile acid-binding protein (I-BABP), a member of the family of intracellular lipid binding proteins plays a key role in the cellular trafficking and metabolic regulation of bile salts. The protein has two internal and, according to a recent study, an additional superficial binding site and binds di- and trihydroxy bile salts with positive cooperativity and a high degree of site-selectivity. Previously, in the apo form, we have identified an extensive network of conformational fluctuations on the millisecond time scale, which cease upon ligation.

Sodium selective ion channel formation in living cell membranes by polyamidoamine dendrimer.

Polyamidoamine (PAMAM) dendrimers are highly charged hyperbranched protein-like polymers that are known to interact with cell membranes. In order to disclose the mechanisms of dendrimer-membrane interaction, we monitored the effect of PAMAM generation five (G5) dendrimer on the membrane permeability of living neuronal cells followed by exploring the underlying structural changes with infrared-visible sum frequency vibrational spectroscopy (SVFS), small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). G5 dendrimers were demonstrated to irreversibly increase the membrane permeability of neurons that could be blocked in low-[Na(+)], but not in low-[Ca(2+)] media suggesting the formation of specific Na(+) permeable channels.

Internal motions and exchange processes in human ileal bile acid binding protein as studied by backbone (15)N nuclear magnetic resonance spectroscopy.

Human ileal bile acid binding protein (I-BABP), a member of the family of intracellular lipid binding proteins, is thought to play a role in the enterohepatic circulation of bile salts. Previously, we have shown by stopped-flow fluorescence analysis that positive binding cooperativity exhibited by I-BABP in its interactions with glycocholate (GCA) and glycochenodeoxycholate (GCDA), the two primary bile salts in humans, is related to a slow conformational change in the protein. In this study, we used backbone (15)N relaxation nuclear magnetic resonance (NMR) techniques to obtain residue-specific information about the internal dynamics of apo I-BABP and the doubly ligated I-BABP:GCA:GCDA complex on various time scales.