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A canonical view of the primary physiological function of myoglobin (Mb) is that it is an oxygen (O2) storage protein supporting mitochondrial oxidative phosphorylation, especially as the tissue O2 partial pressure (P o 2) drops and Mb off-loads O2. Besides O2 storage/transport, recent findings support functions for Mb in lipid trafficking and sequestration, interacting with cellular glycolytic metabolites such as lactate (LAC) and pyruvate (PYR), and "ectopic" expression in some types of cancer cells and in brown adipose tissue (BAT). Data from Mb knockout (Mb−/−) mice and biochemical models suggest additional metabolic roles for Mb, especially regulation of nitric oxide (NO) pools, modulation of BAT bioenergetics, thermogenesis, and lipid storage phenotypes. From these and other findings in the literature over many decades, Mb's function is not confined to delivering O2 in support of oxidative phosphorylation but may serve as an O2 sensor that modulates intracellular P o 2- and NO-responsive molecular signaling pathways. This paradigm reflects a fundamental change in how oxidative metabolism and cell regulation are viewed in Mb-expressing cells such as skeletal muscle, heart, brown adipocytes, and select cancer cells. Here, we review historic and emerging views related to the physiological roles for Mb and present working models illustrating the possible importance of interactions between Mb, gases, and small-molecule metabolites in regulation of cell signaling and bioenergetics. [ABSTRACT FROM AUTHOR]

The odorant binding protein, OBP44a is one of the most abundant proteins expressed in the brain of the developing fruit fly Drosophila melanogaster. Its cellular function has not yet been determined. The OBP family of proteins is well established to recognize hydrophobic molecules. In this study, NMR is employed to structurally characterize OBP44a. NMR chemical shift perturbation measurements confirm that OBP44a binds to fatty acids. Complete assignments of the backbone chemical shifts and secondary chemical shift analysis demonstrate that the apo state of OBP44a is comprised of six α-helices. Upon binding 8(Z)-eicosenoic acid (8(Z)-C20:1), the OBP44a C-terminal region undergoes a conformational change, from unstructured to α-helical. In addition to C-terminal restructuring upon ligand binding, some hydrophobic residues show dramatic chemical shift changes. Surprisingly, several charged residues are also strongly affected by lipid binding. Some of these residues could represent key structural features that OBP44a relies on to perform its cellular function. The NMR chemical shift assignment is the first step towards characterizing the structure of OBP44a and how specific residues might play a role in lipid binding and release. This information will be important in deciphering the biological function of OBP44a during fly brain development. [ABSTRACT FROM AUTHOR]

Abstract Background Fatty acid-binding protein 4 (FABP4) has been associated with cardiovascular disease and diabetes. Acute aerobic exercise increases circulating FABP4 concentrations, but the underlying mechanisms remain unclear. The purpose of this study was to investigate the effects of inhibition of lipolysis by carbohydrate ingestion on circulating FABP4 concentrations during and after acute aerobic exercise in healthy men. Methods Men aged between 20 and 40, with no exercise habits and no metabolic diseases, were recruited. In a randomized crossover design, the participants underwent a carbohydrate-ingestion exercise (CE) and a fasted exercise (FE) trial. The CE trial consisted of 40-min acute aerobic exercise with ingestion of carbohydrates and 60-min bed rest. The FE trial followed the same protocol as the CE trial but without carbohydrate ingestion. Venous blood samples were collected to measure hormones (adrenaline, noradrenaline, and insulin) metabolites (glycerol, free fatty acids, and glucose), and FABP4 concentrations. Ventilation and gas exchange were also collected to measure substrate oxidation. Results Thirteen healthy men participated in and completed both the CE and FE trials. The insulin concentration was more than 4 times higher in the CE trial than in the FE trial (p 2.00). Free fatty acid concentrations were more than 4 times lower in the CE trial than in the FE trial (p 2.04). However, there was no significant difference in the changes in circulating FABP4 concentrations between the CE and FE trials (p = 0.108), which did not change during aerobic exercise and significantly increased post-aerobic exercise in both trials (p 1.212). Changes in FABP4 concentrations following aerobic exercise were not significantly correlated with changes in glycerol or free fatty acid concentrations during aerobic exercise. Conclusions The results suggest that suppression of lipolysis and elevation of insulin are not strongly involved in increases in FABP4 secretion following acute aerobic exercise.

Alzheimer's disease (AD), the most common cause of dementia in the elderly, is characterized by the accumulation of intracellular neurofibrillary tangles, extracellular amyloid plaques, and neuroinflammation. In partnership with microglial cells, astrocytes are key players in the regulation of neuroinflammation. Fatty acid binding protein 7 (FABP7) belongs to a family of conserved proteins that regulate lipid metabolism, energy homeostasis, and inflammation. FABP7 expression is largely restricted to astrocytes and radial glia-like cells in the adult central nervous system. We observed that treatment of primary hippocampal astrocyte cultures with amyloid β fragment 25–35 (Aβ25–35) induces FABP7 upregulation. In addition, FABP7 expression is upregulated in the brain of APP/PS1 mice, a widely used AD mouse model. Co-immunostaining with specific astrocyte markers revealed increased FABP7 expression in astrocytes. Moreover, astrocytes surrounding amyloid plaques displayed increased FABP7 staining when compared to non-plaque-associated astrocytes. A similar result was obtained in the brain of AD patients. Whole transcriptome RNA sequencing analysis of human astrocytes differentiated from induced pluripotent stem cells (i-astrocytes) overexpressing FABP7 identified 500 transcripts with at least a 2-fold change in expression. Gene Ontology enrichment analysis identified (i) positive regulation of cytokine production and (ii) inflammatory response as the top two statistically significant overrepresented biological processes. We confirmed that wild-type FABP7 overexpression induces an NF-κB-driven inflammatory response in human i-astrocytes. On the other hand, the expression of a ligand-binding impaired mutant FABP7 did not induce NF-κB activation. Together, our results suggest that the upregulation of FABP7 in astrocytes could contribute to the neuroinflammation observed in AD. [ABSTRACT FROM AUTHOR]

The objective of the study was to assess the expression of proteins responsible for placental lipid transport in term pregnancies complicated by well-controlled gestational (GDM) and type 1 diabetes mellitus (PGDM). A total of 80 placental samples were obtained from patients diagnosed with PGDM (n = 20), GDM treated with diet (GDMG1, n = 20), GDM treated with diet and insulin (GDMG2, n = 20), and a non-diabetic control group (n = 20). Umbilical and uterine artery blood flows were assessed by means of ultrasound in the period prior to delivery and computer-assisted quantitative morphometry of immunostained placental sections was performed to determine the expression of selected proteins. The morphometric analysis performed for the vascular density-matched placental samples demonstrated a significant increase in the expression of fatty acid translocase (CD36), fatty acid binding proteins (FABP1, FABP4 and FABP5), as well as a decrease in the expression of endothelial lipase (EL) and fatty acid transport protein (FATP4) in the PGDM-complicated pregnancies as compared to the GDMG1 and control groups (p < 0.05). No significant differences with regard to the placental expression of lipoprotein lipase (LPL) and FATP6 protein between GDM/PGDM and non-diabetic patients were noted. Maternal pre-pregnancy weight, body mass index, placental weight as well as the expression of LPL and FABP4 were selected by the linear regression model as the strongest contributors to the fetal birth weight. To conclude, in placentas derived from pregnancies complicated by well-controlled PGDM, the expression of several lipid transporters, including EL, CD36, FATP4, FABP1, FABP4 and FABP5, is altered. Nonetheless, only LPL and FABP4 were significant predictors of the fetal birth weight. [ABSTRACT FROM AUTHOR]

Background: Fatty acid-binding protein 4 (FABP4) has been associated with cardiovascular disease and diabetes. Acute aerobic exercise increases circulating FABP4 concentrations, but the underlying mechanisms remain unclear. The purpose of this study was to investigate the effects of inhibition of lipolysis by carbohydrate ingestion on circulating FABP4 concentrations during and after acute aerobic exercise in healthy men. Methods: Men aged between 20 and 40, with no exercise habits and no metabolic diseases, were recruited. In a randomized crossover design, the participants underwent a carbohydrate-ingestion exercise (CE) and a fasted exercise (FE) trial. The CE trial consisted of 40-min acute aerobic exercise with ingestion of carbohydrates and 60-min bed rest. The FE trial followed the same protocol as the CE trial but without carbohydrate ingestion. Venous blood samples were collected to measure hormones (adrenaline, noradrenaline, and insulin) metabolites (glycerol, free fatty acids, and glucose), and FABP4 concentrations. Ventilation and gas exchange were also collected to measure substrate oxidation. Results: Thirteen healthy men participated in and completed both the CE and FE trials. The insulin concentration was more than 4 times higher in the CE trial than in the FE trial (p < 0.004, effect size [ES] > 2.00). Free fatty acid concentrations were more than 4 times lower in the CE trial than in the FE trial (p < 0.02, ES > 2.04). However, there was no significant difference in the changes in circulating FABP4 concentrations between the CE and FE trials (p = 0.108), which did not change during aerobic exercise and significantly increased post-aerobic exercise in both trials (p < 0.002, ES > 1.212). Changes in FABP4 concentrations following aerobic exercise were not significantly correlated with changes in glycerol or free fatty acid concentrations during aerobic exercise. Conclusions: The results suggest that suppression of lipolysis and elevation of insulin are not strongly involved in increases in FABP4 secretion following acute aerobic exercise. [ABSTRACT FROM AUTHOR]

Fatty acid binding proteins (FABPs) are responsible for the long‐chain fatty acids (FAs) transport inside the cell. However, despite the years, since their structure is known and the many studies published, there is no definitive answer about the stages of the lipid entry‐exit mechanism. Their structure forms a β‐barrel of 10 anti‐parallel strands with a cap in a helix‐turn‐helix motif, and there is some consensus on the role of the so‐called portal region, involving the second α‐helix from the cap (α2), βC–βD, and βE–βF turns in FAs exchange. To test the idea of a lid that opens, we performed a soaking experiment on an h‐FABP crystal in which the cap is part of the packing contacts, and its movement is strongly restricted. Even in these conditions, we observed the replacement of palmitic acid by 2‐Bromohexadecanoic acid (Br‐palmitic acid). Our MD simulations reveal a two‐step lipid entry process: (i) The travel of the lipid head through the cavity in the order of tens of nanoseconds, and (ii) The accommodation of its hydrophobic tail in hundreds to thousands of nanoseconds. We observed this even in the cases in which the FAs enter the cavity by their tail. During this process, the FAs do not follow a single trajectory, but multiple ones through which they get into the protein cavity. Thanks to the complementary views between experiment and simulation, we can give an approach to a mechanistic view of the exchange process. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Entomology is the property of Chinese Journal of Applied Entomology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Male androgenetic alopecia (AGA) is the utmost frequent kind of male baldness. Objective: This study aimed to determine serum levels of A-FABP in individuals with AGA and their putative link to the severity of AGA and other metabolic diseases. Methods: This case-control research comprised 60 male patients with AGA and twenty healthy volunteers of the same age and gender. Medical history, clinical examination, and laboratory testing were performed for all individuals. A-FABP serum levels were determined for all subjects. Human A-FABP ELISA kit was used to assess A-FABP in the serum. Participants' A-FABP serum levels were analysed. Results: AFABP levels in AGA patients were substantially higher than in controls. Conclusion: The pathogenesis of AGA may be aided by the presence of serum A-FABP. With its high sensitivity, specificity, and accuracy rate, it might be regarded a biomarker for early illness detection. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Entomology is the property of Chinese Journal of Applied Entomology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

E. coli strains are created as producers of recombinant β1-adrenoreceptor epitopes as part of chimeric proteins. The corresponding epitope sequences are located in the C-terminal region of the human heart fatty acid binding protein (hH-FABP) and separated from it by the linker sequence (Gly4Ser)3. A solid-phase enzyme-linked immunosorbent assay (ELISA) to detect autoantibodies against the β1-adrenergic receptor in human blood serum based on a recombinant epitope is developed. Blood sera of patients (N = 76) with various diagnoses of cardiopathologies and other diseases are analyzed. A significantly high level of autoantibodies to the β1-adrenergic receptor is detected in some patients with a confirmed diagnosis of cardiovascular diseases, in most cases those with a diagnosis of acute myocardial infarction. [ABSTRACT FROM AUTHOR]

Ordinary small molecule de novo drug design is time-consuming and expensive. Recently, computational tools were employed and proved their efficacy in accelerating the overall drug design process. Molecular dynamics (MD) simulations and a derivative of MD, steered molecular dynamics (SMD), turned out to be promising rational drug design tools. In this paper, we report the first application of SMD to evaluate the binding properties of small molecules toward FABP4, considering our recent interest in inhibiting fatty acid binding protein 4 (FABP4). FABP4 inhibitors (FABP4is) are small molecules of therapeutic interest, and ongoing clinical studies indicate that they are promising for treating cancer and other diseases such as metabolic syndrome and diabetes. [ABSTRACT FROM AUTHOR]

Lipoxygenases are widespread enzymes found in virtually all eukaryotes, including fungi, and, more recently, in prokaryotes. These enzymes act on long-chain polyunsaturated fatty acid substrates (C18 to C20), raising questions regarding how the substrate threads its way from solvent to the active site. Herein, we report a comparison of the temperature dependence of isotope effects on first- and second-order rate constants among single-site variants of the prototypic plant enzyme soybean lipoxygenase-1 substituted at amino acid residues inferred to impact substrate binding. We created 10 protein variants including four amino acid positions, Val-750, Ile-552, Ile-839, and Trp-500, located within a previously proposed substrate portal. The conversion of these bulky hydrophobic side chains to smaller side chains is concluded to increase the mobility of flanking helices, giving rise to increased off rates for substrate dissociation from the enzyme. In this manner, we identified a specific binding network that can regulate movement of the substrate from the solvent to the active site. Taken together with our previous findings on C-H and O2 activation of soybean lipoxygenase-1, these results support the emergence of multiple complementary networks within a single protein scaffold that modulate different steps along the enzymatic reaction coordinate.

The mechanism of urea's action in protein denaturation remains largely unknown. To provide an experimental basis for molecular dynamics (MD) simulations on urea-protein interactions, we investigated the effect of urea on human intestinal fatty acid binding protein (hIFABP) by nuclear magnetic resonance (NMR). Hydrogen-deuterium exchange (HDX) rates at ≤ 2 M urea indicate that urea affects hIFABP in a residue-specific manner via direct urea-protein interactions and preferentially weakens hydrogen bonds between highly protected amides. Residue-specific effects of urea on NMR peak intensities and chemical shifts further support the presence of direct urea-protein interactions. Two-dimensional (2D) water-rotating frame Overhauser enhancement (ROE) data shows one protein-bound water molecule in contact with Val66 and Trp82, one putative bound water molecule in interaction with Thr76 and E-F loop, and that urea at low concentrations cannot displace these protein-bound water molecules. Our urea-nuclear Overhauser effect (NOE) experiments using 15N-urea further show no tightly protein-bound urea molecules. Our results thus suggest specific, but weak or transient, urea-protein interactions, supporting the direct interaction model of urea denaturation.

Aims: Abnormal lipid metabolism is involved in the development of osteoarthritis (OA). Growth differentiation factor 11 (GDF11) is crucial in inhibiting the differentiation of bone marrow mesenchymal stem cells into adipocytes. However, whether GDF11 participates in the abnormal adipogenesis of chondrocytes in OA cartilage is still unclear. Methods: Six-week-old female mice were subjected to unilateral anterior crossbite (UAC) to induce OA in the temporomandibular joint (TMJ). Histochemical staining, immunohistochemical staining (IHC), and quantitative real-time polymerase chain reaction (qRT-PCR) were performed. Primary condylar chondrocytes of rats were stimulated with fluid flow shear stress (FFSS) and collected for oil red staining, immunofluorescence staining, qRT-PCR, and immunoprecipitation analysis. Results: Abnormal adipogenesis, characterized by increased expression of CCAAT/enhancer-binding protein α (CEBPα), fatty acid binding protein 4 (FABP4), Perilipin1, Adiponectin (AdipoQ), and peroxisome proliferator-activated receptor γ (PPARγ), was enhanced in the degenerative cartilage of TMJ OA in UAC mice, accompanied by decreased expression of GDF11. After FFSS stimulation, there were fat droplets in the cytoplasm of cultured cells with increased expression of PPARγ, CEBPα, FABP4, Perilipin1, and AdipoQ and decreased expression of GDF11. Exogenous GDF11 inhibited increased lipid droplets and expression of AdipoQ, CEBPα, and FABP4 induced by FFSS stimulation. GDF11 did not affect the change in PPARγ expression under FFSS, but promoted its post-translational modification by small ubiquitin-related modifier (SUMOylation). Local injection of GDF11 alleviated TMJ OA-related cartilage degeneration and abnormal adipogenesis in UAC mice. Conclusion: Abnormal adipogenesis of chondrocytes and decreased GDF11 expression were observed in degenerative cartilage of TMJ OA. GDF11 supplementation effectively inhibits the adipogenesis of chondrocytes and thus alleviates TMJ condylar cartilage degeneration. GDF11 may inhibit the abnormal adipogenesis of chondrocytes by affecting the SUMOylation of PPARγ. Cite this article: Bone Joint Res 2022;11(7):453–464.

Multiple myeloma is an incurable plasma cell malignancy with only a 53% 5-year survival rate. There is a critical need to find new multiple myeloma vulnerabilities and therapeutic avenues. Herein, we identified and explored a novel multiple myeloma target: the fatty acid binding protein (FABP) family. In our work, myeloma cells were treated with FABP inhibitors (BMS3094013 and SBFI-26) and examined in vivo and in vitro for cell cycle state, proliferation, apoptosis, mitochondrial membrane potential, cellular metabolism (oxygen consumption rates and fatty acid oxidation), and DNA methylation properties. Myeloma cell responses to BMS309403, SBFI-26, or both, were also assessed with RNA sequencing (RNA-Seq) and proteomic analysis, and confirmed with western blotting and qRT-PCR. Myeloma cell dependency on FABPs was assessed using the Cancer Dependency Map (DepMap). Finally, MM patient datasets (CoMMpass and GEO) were mined for FABP expression correlations with clinical outcomes. We found that myeloma cells treated with FABPi or with FABP5 knockout (generated via CRISPR/Cas9 editing) exhibited diminished proliferation, increased apoptosis, and metabolic changes in vitro. FABPi had mixed results in vivo, in two pre-clinical MM mouse models, suggesting optimization of in vivo delivery, dosing, or type of FABP inhibitors will be needed before clinical applicability. FABPi negatively impacted mitochondrial respiration and reduced expression of MYC and other key signaling pathways in MM cells in vitro. Clinical data demonstrated worse overall and progression-free survival in patients with high FABP5 expression in tumor cells. Overall, this study establishes the FABP family as a potentially new target in multiple myeloma. In MM cells, FABPs have a multitude of actions and cellular roles that result in the support of myeloma progression. Further research into the FABP family in MM is warrented, especially into the effective translation of targeting these in vivo.

The existence of abnormal cytokine profile in Sjögren's syndrome (SS) may contribute to find potential SS biomarkers and accompanying comorbidities. We aimed to investigate and compare gene expressions in the labial salivary glands of SS and of healthy subjects (HS) by means of microarray analysis. The study group comprised 8 SS patients and 8 HS in microarray analysis. The relative gene expression changes were validated with real time quantitative polymerase chain reaction in 25 SS and 20 HS. Among the differently expressed genes belonging to the "cellular response to cytokine stimulus", "cytokine-mediated signaling pathway" and "innate immune response" ontology groups with a fold change >1.5 and with a p value < 0.05, the adiponectin, C1Q and collagen domain containing (ADIPOQ), S100 calcium binding protein A9 (S100A9), leptin receptor (LEPR), and fatty acid binding protein 4 (FABP4) gene expressions in SS group were higher than in HS. Increased expression of the assessed genes are determined by the presence of SS and the accompanying inflammation and may be a valuable diagnostic biomarker of SS. Their selected systemic effects may suggest their role as potential prognostic biomarkers of the risk of accelerated atherosclerosis and cardiovascular complications in SS. [ABSTRACT FROM AUTHOR]

The work considers a combination of three enhancing approaches for immunochromatographic assay (ICA) and the integration of their impacts into changes of the limit of detection (LOD). Human fatty acid binding protein (FABP), an early biomarker of acute myocardial infarction, was the target analyte. Starting from the common ICA protocol with an LOD equal to 11.2 ng/mL, three approaches were realized: (1) replacement of spherical gold nanoparticles with gold nanoflowers having a branched surface (20-fold lowering the LOD); (2) enhanced labeling of immune complexes via nanoparticle aggregates (15-fold lowering); (3) in-situ growth of bound nanoparticles by reduction of gold salts (3-fold lowering). Single and combined implementations of these approaches have been studied. It has been shown that the LOD decrease for combined approaches is close to the multiplied contribution of each of them. The final LOD for FABP was 0.05 ng/mL, which is 220 times lower than the LOD for the common ICA protocol. The efficiency of the enhanced ICA with three combined approaches was confirmed by testing human serum samples for FABP presence and content. The development presents a new efficient technique for rapid sensitive detection of FABP for medical diagnostics. Moreover, the demonstrated multiple enhancements could be applied for various demanded analytes. [ABSTRACT FROM AUTHOR]

Simple Summary: Liver damage is a common occurrence following sustained, heavy alcohol consumption. One of the earliest pathologies associated with alcohol-dependent liver disease is increased hepatic fat accumulation. In healthy individuals, fatty acid binding protein-1 plays an important role in transporting lipids in hepatocytes. However, in alcohol-dependent liver disease, fatty acid binding protein-4 (a protein normally expressed in fat storing cells and white blood cells) is produced by hepatocytes and can stimulate liver cancer growth. In this study, we report that alcohol metabolism via cytochrome P450 2E1 drives increased fatty acid binding protein-4 production and fat accumulation. These data suggest that increased fatty acid binding protein-4 production may promote tumor growth in cancer cells in alcohol-dependent liver disease. Fatty acid binding protein-4 (FABP4) is not normally expressed in the liver but is induced in alcohol-dependent liver disease (ALD)). This study sought to identify mechanisms whereby ethanol (EtOH) metabolism alters triglyceride accumulation and FABP4 production. Human hepatoma cells which were stably transfected to express alcohol dehydrogenase (ADH) or cytochrome P4502E1 (CYP2E1) were exposed to EtOH in the absence/presence of inhibitors of ADH (4-methylpyrazole) or CYP2E1 (chlormethiazole). Cells were analyzed for free fatty acid (FFA) content and FABP4 mRNA, then culture medium assayed for FABP4 levels. Cell lysates were analyzed for AMP-activated protein kinase-α (AMPKα), Acetyl-CoA carboxylase (ACC), sterol regulatory element binding protein-1c (SREBP-1c), and Lipin-1β activity and localization in the absence/presence of EtOH and pharmacological inhibitors. CYP2E1-EtOH metabolism led to increased FABP4 mRNA/protein expression and FFA accumulation. Analysis of signaling pathway activity revealed decreased AMPKα activation and increased nuclear-SREBP-1c localization following CYP2E1-EtOH metabolism. The role of AMPKα-SREBP-1c in regulating CYP2E1-EtOH-dependent FFA accumulation and increased FABP4 was confirmed using pharmacological inhibitors and over-expression of AMPKα. Inhibition of ACC or Lipin-1β failed to prevent FFA accumulation or changes in FABP4 mRNA expression or protein secretion. These data suggest that CYP2E1-EtOH metabolism inhibits AMPKα phosphorylation to stimulate FFA accumulation and FABP4 protein secretion via an SREBP-1c dependent mechanism. [ABSTRACT FROM AUTHOR]

Fatty acid binding protein (FABP4) inhibitors are of synthetic and therapeutic interest and ongoing clinical studies indicate that they may be a promise for the treatment of cancer, as well as other diseases. As part of a broader research effort to develop more effective FABP4 inhibitors, we sought to identify new structures through a two-step computing assisted molecular design based on the established scaffold of a co-crystallized ligand. Novel and potent FABP4 inhibitors have been developed using this approach and herein we report the synthesis, biological evaluation and molecular docking of the 4-amino and 4-ureido pyridazinone-based series. [ABSTRACT FROM AUTHOR]

Background: The 15kDa cytoplasmic fatty acid-binding protein family (FABPs) is one of the most exciting novel indicators for the diagnosis of renal damage. Objective: The aim of this study was to investigate the relation of circulating FABP1 and FABP2 levels as clinical and biochemical markers and varying stages of nephropathy in senior T2DM patients. Patients and Methods: This case-control study included a total of 60 patients with Type 2 diabetes and 30 nondiabetic controls, attending and followed up at Out-Patient Clinics, Department of Internal Medicine, Zagazig University Hospitals. Patients were divided into 3 equal groups: Group I: healthy control group; Group II: diabetic group without incidence of diabetic nephropathy; Group III: diabetic nephropathy group. All patients were tested for FABP1 and FABP2. Results: FABP1 and FABP2 levels significantly varied among the study's three groups. The significance was referred to the higher expression of FABP1 and FABP2 in group II and III than controls and higher expression in group III than group II as illustrated in post-hoc analysis. There were significant positive Pearson correlations between FABP1, FABP2 and serum creatinine, serum urea, urine albumin-creatinine ratio (uACR) while the correlation between FABP1, FABP2 and eGFR was inverse correlation of significance. Conclusion: It could be concluded that FABP1 and FABP2 may be novel biomarkers of diabetic nephropathy. FABP1 has an 87% sensitivity and an 83% specificity for the diagnosis of diabetic nephropathy at a cut-off value equal to 2.7 ng/dL. FABP2 has a 93% sensitivity and a 33% specificity for diagnosing diabetic nephropathy at a cut-off value equal to 0.16 ng/dL. [ABSTRACT FROM AUTHOR]

The endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide are among the best studied lipid messengers in the brain. By activating cannabinoid receptors in the CNS, endocannabinoids tune synaptic function, thereby influencing a variety of physiological and behavioural processes. Extensive research conducted over the last few decades has considerably enhanced our understanding of the molecular mechanisms and physiological functions of the endocannabinoid system. It is now well-established that endocannabinoids are synthesized by postsynaptic neurons and serve as retrograde messengers that suppress neurotransmitter release at central synapses. While the detailed mechanisms by which endocannabinoids gate synaptic function and behavioural processes are relatively well characterized, the mechanisms governing endocannabinoid transport at central synapses remain ill defined. Recently, several studies have begun to unravel the mechanisms governing intracellular and intercellular endocannabinoid transport. In this review, we will focus on new advances in the mechanisms of intracellular and synaptic endocannabinoid transport in the CNS. LINKED ARTICLES: This article is part of a themed issue on New discoveries and perspectives in mental and pain disorders. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.17/issuetoc. [ABSTRACT FROM AUTHOR]

Fatty acid binding proteins (FABPs) are proteins found in the cytosol that contribute to disorders related to the cardiovascular system, including atherosclerosis and metabolic syndrome. Functionally, FABPs serve as intracellular lipid chaperones, interacting with hydrophobic ligands and mediating their transportation to sites of lipid metabolism. To date, nine unique members of the FABP family (FABP 1–9) have been identified and classified according to the tissue in which they are most highly expressed. In the literature, FABP3 has been shown to be a promising clinical biomarker for coronary and peripheral artery disease. Given the rising incidence of cardiovascular disease and its associated morbidity/mortality, identifying biomarkers for early diagnosis and treatment is critical. In this review, we highlight key discoveries and recent studies on the role of FABP3 in cardiovascular disorders, with a particular focus on its clinical relevance as a biomarker for peripheral artery disease. [ABSTRACT FROM AUTHOR]

Gram-positive bacteria utilize a Fatty Acid Kinase (FAK) complex to harvest fatty acids from the environment. This complex consists of the fatty acid kinase, FakA, and an acyl carrier protein, FakB, and is known to impact virulence and disease outcomes. Despite some recent studies, there remain many outstanding questions as to the enzymatic mechanism and structure of FAK. To better address this knowledge gap, we used a combination of modeling, biochemical, and cell-based approaches to build on prior proposed models and identify critical details of FAK activity. Using bio-layer interferometry, we demonstrated nanomolar affinity between FakA and FakB which also indicates that FakA is dimer when binding FakB. Additionally, targeted mutagenesis of the FakA Middle domain demonstrates it possesses a metal binding pocket that is critical for FakA dimer stability and FAK function in vitro and in vivo. Lastly, we solved structures of the apo and ligand-bound FakA kinase domain to capture the molecular changes in the protein following ATP binding and hydrolysis. Together, these data provide critical insight into the structure and function of the FAK complex which is essential for understanding its mechanism., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

To clarify the characteristics of Spirometra erinaceieuropaei fatty acid-binding protein (SeFABP) and obtain its recombinant protein, the basic physio-biochemistry characteristics, signal peptides, antigen epitopes, transmembrane domains, secondary and tertiary structures, multi sequence alignment and molecular evolutionary tree of SeFABP were predicted and analyzed. On this basis, SeFABP was wholegenome synthesized and cloned into prokaryotic expression vector. The recombinant plasmid pET- 30a(+)-SeFABP was constructed, then transformed into E. coli BL21 (DE3) and induced by IPTG. The purified SeFABP was obtained by Ni-IDA resins affinity chromatography, and were finally confirmed by SDS-PAGE and Western blot. The results showed that SeFABP, a stable intracellular protein without signal peptide and transmembrane region, was composed of 130 amino acids (AA). It contained 10 phosphorylation sites and 7 post-translational modification sites. Both methods predicted that SeFABP contained 5 linear epitopes, and were highly coincident, indicating that SeFABP had good immunogenicity. Its secondary structure contains 2 a-helix (13.07%), 10 ß-sheet (56.92%) and 30% random coli. The comparison of multiple FABPs sequences showed that the species were identical and highly conserved at multiple AA sites. Specifically, SeFABP has the highest similarity with T. multiceps and M. vogae, close to 37%, but the lowest similarity with F. hepatica and F. gigatica, close to 22%. Plasmid double enzyme digestion and sequencing showed that the fully synthesized SeFABP fragment was accurately cloned and connected to the expression vector pET-30a(+)-SeFABP. After induction, the recombinant SeFABP was successfully expressed in the form of inclusion body. SDS-PAGE and Western blot showed a 15kD band, indicating that the recombinant was successfully purified. In conclusion, the characteristics of SeFABP and its high-purity recombinant protein were obtained, provides a basis for future research based on SeFABP in vaccine development and drug design. [ABSTRACT FROM AUTHOR]

Deterioration of metabolic health is a hallmark of aging and generally assumed to be detrimental to longevity. Exposure to a high-calorie diet impairs metabolism and accelerates aging; conversely, calorie restriction (CR) prevents age-related metabolic diseases and extends lifespan. However, it is unclear whether preservation of metabolic health is sufficient to extend lifespan. We utilized a genetic mouse model lacking Fabp4/5 that confers protection against metabolic diseases and shares molecular and lipidomic features with CR to address this question. Fabp-deficient mice exhibit extended metabolic healthspan, with protection against insulin resistance and glucose intolerance, inflammation, deterioration of adipose tissue integrity, and fatty liver disease. Surprisingly, however, Fabp-deficient mice did not exhibit any extension of lifespan. These data indicate that extension of metabolic healthspan in the absence of CR can be uncoupled from lifespan, indicating the potential for independent drivers of these pathways, at least in laboratory mice.

Ordinary small molecule de novo drug design is time-consuming and expensive. Recently, computational tools were employed and proved their efficacy in accelerating the overall drug design process. Molecular dynamics (MD) simulations and a derivative of MD, steered molecular dynamics (SMD), turned out to be promising rational drug design tools. In this paper, we report the first application of SMD to evaluate the binding properties of small molecules toward FABP4, considering our recent interest in inhibiting fatty acid binding protein 4 (FABP4). FABP4 inhibitors (FABP4is) are small molecules of therapeutic interest, and ongoing clinical studies indicate that they are promising for treating cancer and other diseases such as metabolic syndrome and diabetes.

Alzheimer's disease (AD) is a progressive neurodegenerative disease affecting millions of people worldwide. AD is characterized by the presence of extracellular plaques composed of aggregated/oligomerized β-amyloid peptides with Aβ42 peptide representing a major isoform in the senile plaques. Given the pathological significance of Aβ42 in the progression of AD, there is considerable interest in understanding the structural ensembles for soluble monomer and oligomeric forms of Aβ42. This report describes an efficient method to express and purify high quality (15)N isotope-labeled Aβ42 for structural studies by NMR. The protocol involves utilization of an auto induction system with (15)N isotope labeled medium, for high-level expression of Aβ42 as a fusion with IFABP. After the over-expression of the (15)N isotope-labeled IFABP-Aβ42 fusion protein in the inclusion bodies, pure (15)N isotope-labeled Aβ42 peptide is obtained following a purification method that is streamlined and improved from the method originally developed for the isolation of unlabeled Aβ42 peptide (Garai et al., 2009). We obtain a final yield of ∼ 6 mg/L culture for (15)N isotope-labeled Aβ42 peptide. Mass spectrometry and (1)H-(15)N HSQC spectra of monomeric Aβ42 peptide validate the uniform incorporation of the isotopic label. The method described here is equally applicable for the uniform isotope labeling with (15)N and (13)C in Aβ42 peptide as well as its other variants including any Aβ42 peptide mutants.

Bronchopulmonary dysplasia (BPD) is a chronic lung disease characterized by interrupted alveologenesis and alveolar simplification caused by oxygen therapy in premature infants. Metabolic dysfunction is involved in the pathogenesis of BPD. Fatty acid‐binding protein 4 (FABP4) is significantly increased in specific lung tissues in patients with BPD. Therefore, we investigated whether BMS309403, an FABP4 inhibitor that can mitigate tissue fibrosis, can regulate pulmonary fibrotic processes in newborn rats exposed to hyperoxia. Newborn rat pups were exposed to room air (RA; 21% O2) or 85% O2 from 5 to 14 days of age and were then allowed to recover in RA until 29 days of age. They received intraperitoneal injection with placebo (phosphate‐buffered saline [PBS]) or BMS 309403 (0.5 mg or 1.0 mg kg−1 d−1) every other day from 4 to 14 days of age then were divided into O2 plus PBS or low dose or high dose and RA plus PBS or low dose or high dose groups. We assessed lung histology and evaluated lung collagen I, FABP4 as well as TGF‐β1 expression at 14 and 29 days of age. In the hyperoxia injury‐recovery model, prophylactic BMS309403 treatment reduced mean linear intercept values and FABP4 expression (p < 0.001). Prophylactic BMS309403 treatment mitigated pulmonary fibrosis and TGF‐β1 expression immediately after hyperoxia exposure (p < 0.05). The attenuation of hyperoxia‐induced alveolar developmental impairment and pulmonary fibrosis by FABP4 inhibition indicated that such inhibition has potential clinical and therapeutic applications. [ABSTRACT FROM AUTHOR]

Per‐ and polyfluoroalkyl substances (PFAS) are a large group of synthetic fluorinated chemicals with surface active and water‐repellent properties. The combination of wide‐spread use in numerous consumer and industrial products and extended biological half‐lives arising from strong carbon–fluorine bonds has led to significant accumulation of PFAS in humans. As most human interaction with PFAS comes from ingestion, it is important to be able to detect PFAS in drinking water as well as in agricultural water. Here we present an approach to designing a fluorescence‐based biosensor for the rapid detection of PFAS based on human liver fatty acid binding protein (hLFABP). Introduction of solvatochromic fluorophores within the ligand binding pocket (L50) allowed for intrinsic detection of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and perfluorohexanesulfonic acid (PFHxS) via blue‐shifts in fluorescence emission spectra. Initially, a single tryptophan mutation (L50W) was found to be able to detect PFOA with a limit of detection (LOD) of 2.8 ppm. We improved the sensitivity of the biosensor by exchanging tryptophan for the thiol reactive fluorophore, acrylodan. The acrylodan conjugated C69S/F50C hLFABP variant is capable of detecting PFOA, PFOS, and PFHxS in PBS with LODs of 112 ppb, 345 ppb, and 1.09 ppm, respectively. The protein‐based sensor is also capable of detecting these contaminants at similar ranges in spiked environmental water samples, including samples containing an interfering anionic surfactant sodium dodecyl sulfate. Overall, this study demonstrates engineered hLFABP is a useful platform for detection of PFAS in environmental water samples and highlights its ease of use and versatility in field applications. [ABSTRACT FROM AUTHOR]

Introduction: Atrial Fibrillation (AF) is the most common cardiac arrythmia in the world. Structural remodeling and fatty acid metabolism dysregulation are believed to play a role in the development of AF. This study explored different biomarkers in the blood of AF patients and a control population to determine if there was a significant difference between the two groups. Material and Methods: Plasma samples were collected from 73 patients with confirmed diagnosis of AF from Loyola University Clinic. Control group represented commercially available plasma (n = 50). Sandwich ELISA kits were used to quantify the collagen remodeling proteins and liver type fatty acid binding protein (L-FABP) in the AF population and the control population. Non-esterified fatty acids (NEFAs) were measured using an enzymatic colorimetric kit from Wako Diagnostics. Statistical analyses were performed using GraphPad Prism. Results: All the collagen remodeling biomarkers were significantly higher in AF patients compared to the control group. The fatty acid dysregulation biomarkers were elevated in the AF patients. Spearman correlation analyses yielded significant correlations between L-FABP and TIMP-1 (r = 0.47, P < 0.001), NEFA and TIMP-2 (r = 0.41, P = 0.002), NEFA and ICTP (r = 0.41, P =0.002), and NEFA and PIIINP (r = 0.61, P < 0.0001). Summary and Conclusions: The elevation of collagen remodeling biomarkers suggests an upregulation of these biomarkers and their potential role in AF, which may contribute to atrial fibrosis. L-FABP and NEFAs were elevated in AF patients. The correlations between the collagen remodeling and fatty acid dysregulation biomarkers may be due to their involvement in structural remodeling of the atria. [ABSTRACT FROM AUTHOR]

The morbidity and mortality rates for acute myocardial infarction (AMI) have been growing rapidly in the recent years, causing a significant socio-economic damage. The cardiospecific biomarkers play an important role in the diagnosis and prediction of AMI. The purpose of this review is to summarize the information about the main existing cardiac biomarkers and their diagnostic and prognostic value for patients with AMI. The currently existing cardiac biomarkers of AMI may be divided into several groups: biomarkers of necrosis and ischemia of cardiomyocytes, neuroendocrine biomarkers, inflammatory biomarkers, as well as a number of new AMI biomarkers, the diagnostic value of which is still poorly understood in AMI. In the first part of the review, we discuss the diagnostic and prognostic value of the biomarkers of myocardial necrosis and ischemia (aspartate aminotransferase; creatine phosphokinase and its isoform MB; cardiac troponins; myoglobin; BB-isoform of glycogen phosphorylase; ischemia-modified albumin; cardiac protein binding fatty acids) and neuroendocrine biomarkers of AMI (natriuretic peptides; adrenomedulline; copeptin, catestatin; components of the renin-angiotensin-aldosterone system).

Background: Peripheral arterial disease (PAD) affects more than 150 million people worldwide and is associated with high rates of lower extremity amputation, myocardial infarction, stroke and death. Fatty acid binding protein 3 (FABP3) is released into circulation in patients with skeletal muscle injury. In this pilot study, we investigated a possible association between PAD and blood levels of FABP3. Methods: Blood samples were collected from patients with clinical symptoms and diagnostic findings indicative of PAD (PAD group; ankle-brachial index [ABI] 0.9; n = 75) presenting to vascular surgery ambulatory clinics at St. Michael's Hospital. Plasma samples were analyzed by protein multiplex to quantify FABP3 levels. Results: PAD patients were found to have higher blood levels of FABP3 compared to patients without PAD (mean 3.90 ± 1.69 vs 2.03 ± 0.78; P < .001). A subgroup analysis demonstrated that the FABP3 levels were increased by almost two-fold in patients with PAD, independent of coronary artery disease (P < .001) or diabetes mellitus status (P < .001). Moreover, a significant negative correlation between FABP3 and the ABI was observed in PAD and patients without PAD matched groups (r = –0.51; P = .001). Last, immunohistochemistry demonstrated elevated expressions of FABP3 within skeletal muscle obtained from patients with the most severe form of PAD, chronic limb-threatening ischemia, when compared with patients without PAD. Conclusions: Patients with PAD have elevated plasma levels of FABP3. An increasing severity of PAD is associated with higher FABP3 levels. : Clinical Relevance: There is a pressing need for a simple, readily accessible, blood-based biomarker for PAD. In this study, we found elevated levels of FABP3 in patients with PAD. This increase in FABP3 was irrespective of history of coronary artery disease or diabetes. Furthermore, our data suggest that an increasing severity of PAD is associated with higher FABP3 levels. Subsequently, FABP3 may be a potential diagnostic biomarker for PAD. However, further studies are needed to confirm the capability of FABP3 to serve as a valid and reliable biomarker for PAD.

Adipocyte differentiation of bovine adipose-derived stem cells (ASC) was induced by foetal bovine serum (FBS), biotin, pantothenic acid, insulin, rosiglitazone, dexamethasone and 3-isobutyl-1-methylxanthine, followed by incubation in different media to test the influence of ascorbic acid (AsA), bovine serum lipids (BSL), FBS, glucose and acetic acid on transdifferentiation into functional adipocytes. Moreover, different culture plate coatings (collagen-A, gelatin-A or poly-L-lysine) were tested. The differentiated ASC were subjected to Nile red staining, DAPI staining, immunocytochemistry and quantitative reverse transcription PCR (for NT5E, THY1, ENG, PDGFRα, FABP4, PPARγ, LPL, FAS, GLUT4). Nile red quantification showed a significant increase in the development of lipid droplets in treatments with AsA and BSL without FBS. The presence of BSL induced a prominent increase in FABP4 mRNA abundance and in FABP4 immunofluorescence signals in coincubation with AsA. The abundance of NT5E, ENG and THY1 mRNA decreased or tended to decrease in the absence of FBS, and ENG was additionally suppressed by AsA. DAPI fluorescence was higher in cells cultured in poly-L-lysine or gelatin-A coated wells. In additional experiments, the multi-lineage differentiation potential to osteoblasts was verified in medium containing ß-glycerophosphate, dexamethasone and 1,25-dihydroxyvitamin D3 using alizarin red staining. In conclusion, bovine ASC are capable of multi-lineage differentiation. Poly-L-lysine or gelatin-A coating, the absence of FBS, and the presence of BSL and AsA favour optimal transdifferentiation into adipocytes. AsA supports transdifferentiation via a unique role in FABP4 induction, but this is not linearly related to the primarily BSL-driven lipid accumulation. Abbreviations: AcA: acetic acid; AsA: ascorbic acid; ASC: adipose-derived stem cells; BSL: bovine serum lipids; DAPI: 4´,6-diamidino-2-phenylindole; DLK: delta like non-canonical notch ligand; DMEM: Dulbecco’s modified Eagle’s medium; DPBS: Dulbecco’s phosphate-buffered saline; ENG: endoglin; FABP: fatty acid binding protein; FAS: fatty acid synthase; GLUT4: glucose transporter type 4; IBMX: 3-isobutyl-1-methylxanthine; LPL: lipoprotein lipase; MSC: mesenchymal stem cells; α-MEM: α minimum essential medium; NT5E: ecto-5ʹ-nucleotidase; PDGFRα: platelet derived growth factor receptor α; PPARγ: peroxisome proliferator activated receptor γ; RPS19: ribosomal protein S19; SEM: standard error of the mean; THY1: Thy-1 cell surface antigen; TRT: treatment; TRT-Con: treatment negative control; YWHAZ: tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta

Aim. To assess the severity of myocardial damage and inflammation after radiofrequency ablation in children and adolescents using biochemical markers.Material and methods. The study included 58 children with tachyarrhythmias (Wolff-Parkinson-White (WPW) syndrome, WPW phenomenon, atrial tachycardia, paroxysmal atrioventricular reciprocating tachycardia, ventricular tachycardia) who underwent catheter ablation from July to October 2019. Before and after surgical treatment (after 2 hours and 5 days), the blood concentrations of myocardial damage and inflammation biomarkers (myoglobin, creatine phosphokinase-MB, interleukin-8, C-reactive protein, tumor necrosis factor alpha, metalloproteinase (MMP)-2, MMP-9, heart-type fatty acid binding protein). During the operation, catheter ablation parameters (power, temperature, application duration), the localization of arrhythmogenic focus and the type of ablation catheter were recorded. Their relationship with changes in the concentration of biochemical markers before and after intervention was studied.Results. Two hours after the operation, the concentrations of myoglobin, creatine phosphokinase-MB, MMP-9, heart-type fatty acid binding protein were increased several times (p

ABSTRACT Due to their phylogenetic proximity to humans, nonhuman primates (NHPs) are considered an adequate choice for a basic and preclinical model of sepsis. Gram-negative bacteria are the primary causative of sepsis. During infection, bacteria continuously release the potent toxin lipopolysaccharide (LPS) into the bloodstream, which triggers an uncontrolled systemic inflammatory response leading to death. Our previous research has demonstrated in vitro and in vivo using a mouse model of septic shock that Fh15, a recombinant variant of the Fasciola hepatica fatty acid binding protein, acts as an antagonist of Toll-like receptor 4 (TLR4) suppressing the LPS-induced proinflammatory cytokine storm. The present communication is a proof-of concept study aimed to demonstrate that a low-dose of Fh15 suppresses the cytokine storm and other inflammatory markers during the early phase of sepsis induced in rhesus macaques by intravenous (i.v.) infusion with lethal doses of live Escherichia coli. Fh15 was administered as an isotonic infusion 30 min prior to the bacterial infusion. Among the novel findings reported in this communication, Fh15 (i) significantly prevented bacteremia, suppressed LPS levels in plasma, and the production of C-reactive protein and procalcitonin, which are key signatures of inflammation and bacterial infection, respectively; (ii) reduced the production of proinflammatory cytokines; and (iii) increased innate immune cell populations in blood, which suggests a role in promoting a prolonged steady state in rhesus macaques even in the presence of inflammatory stimuli. This report is the first to demonstrate that a F. hepatica-derived molecule possesses potential as an anti-inflammatory drug against sepsis in an NHP model. IMPORTANCE Sepsis caused by Gram-negative bacteria affects 1.7 million adults annually in the United States and is one of the most important causes of death at intensive care units. Although the effective use of antibiotics has resulted in improved prognosis of sepsis, the pathological and deathly effects have been attributed to the persistent inflammatory cascade. There is a present need to develop anti-inflammatory agents that can suppress or neutralize the inflammatory responses and prevent the lethal consequences of sepsis. We demonstrated here that a small molecule of 14.5 kDa can suppress the bacteremia, endotoxemia, and many other inflammatory markers in an acute Gram-negative sepsis rhesus macaque model. These results reinforce the notion that Fh15 constitutes an excellent candidate for drug development against sepsis.

The work considers a combination of three enhancing approaches for immunochromatographic assay (ICA) and the integration of their impacts into changes of the limit of detection (LOD). Human fatty acid binding protein (FABP), an early biomarker of acute myocardial infarction, was the target analyte. Starting from the common ICA protocol with an LOD equal to 11.2 ng/mL, three approaches were realized: (1) replacement of spherical gold nanoparticles with gold nanoflowers having a branched surface (20-fold lowering the LOD); (2) enhanced labeling of immune complexes via nanoparticle aggregates (15-fold lowering); (3) in-situ growth of bound nanoparticles by reduction of gold salts (3-fold lowering). Single and combined implementations of these approaches have been studied. It has been shown that the LOD decrease for combined approaches is close to the multiplied contribution of each of them. The final LOD for FABP was 0.05 ng/mL, which is 220 times lower than the LOD for the common ICA protocol. The efficiency of the enhanced ICA with three combined approaches was confirmed by testing human serum samples for FABP presence and content. The development presents a new efficient technique for rapid sensitive detection of FABP for medical diagnostics. Moreover, the demonstrated multiple enhancements could be applied for various demanded analytes.

Fatty acid binding proteins (FABPs) are a family of amphiphilic transport proteins with high diversity in terms of their amino acid sequences and binding preferences. Beyond their main biological role as cytosolic fatty acid transporters, many aspects regarding their binding mechanism and functional specializations in human cells remain unclear. In this work, the binding properties and thermodynamics of FABP3, FABP4, and FABP5 were analyzed under various physical conditions. For this purpose, the FABPs were loaded with fatty acids bearing fluorescence or spin probes as model ligands, comparing their binding affinities via microscale thermophoresis (MST) and continuous-wave electron paramagnetic resonance (CW EPR) spectroscopy. The CW EPR spectra of non-covalently bound 5- and 16-DOXYL stearic acid (5/16-DSA) deliver in-depth information about the dynamics and chemical environments of ligands inside the binding pockets of the FABPs. EPR spectral simulations allow the construction of binding curves, revealing two different binding states ('intermediately' and 'strongly' bound). The proportion of bound 5/16-DSA depends strongly on the FABP concentration and the temperature but with remarkable differences between the three isoforms. Additionally, the more dynamic state ('intermediately bound') seems to dominate at body temperature with thermodynamic preference. The ligand binding studies were supplemented by aggregation studies via dynamic light scattering and bioinformatic analyses. Beyond the remarkably fine-tuned binding properties exhibited by each FABP, which were discernible with our EPR-centered approach, the results of this work attest to the power of simple spectroscopic experiments to provide new insights into the ligand binding mechanisms of proteins in general on a molecular level., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: As many as 200 million people around the world are affected with peripheral artery disease (PAD), a long-term atherosclerotic problem. The majority of individuals with PAD are asymptomatic, but those who do experience symptoms, such as limb claudication or complete tissue loss, should seek medical attention right away. PAD and its consequences are widespread because of the worldwide growth in the frequency of Type 2 Diabetes Mellitus (T2DM) and the ageing of the general population. Peripheral artery disease can be caused by a combination of vessel wall stiffness and T2DM. Fatty acid binding proteins (FABPs) have been related to the onset of insulin resistance and other manifestations of the metabolic syndrome, and it has been shown that FABPs play an important role in metabolic control. FABP has been linked to fatty acid absorption and chylomicron release in the gastrointestinal tract, according to studies. Objective: The present review aims to assess of possible role of FABPs in T2DM and PAD. Method: FABPs, T2DM and PAD were all looked for in PubMed, Google scholar, and Science direct. References from relevant literature were also evaluated by the authors, but only the most recent or complete study from January 2000 to May 2021 was included. Due to the lack of sources for translation, documents in languages other than English have been ruled out. Papers that did not fall under the purview of major scientific investigations, such as unpublished manuscripts, oral presentations, conference abstracts, and dissertations, were omitted. Conclusion: High levels of some of FABPs in the blood have been linked to both the existence and severity of PAD. [ABSTRACT FROM AUTHOR]

Sortilin is a neuronal receptor for apolipoprotein E (apoE). Sortilindependent uptake of lipidated apoE promotes conversion of polyunsaturated fatty acids (PUFA) into neuromodulators that induce anti-inflammatory gene expression in the brain. This neuroprotective pathway works with the apoE3 variant but is lost with the apoE4 variant, the main risk factor for Alzheimer's disease (AD). Here, we elucidated steps in cellular handling of lipids through sortilin, and why they are disrupted by apoE4. Combining unbiased proteome screens with analyses in mouse models, we uncover interaction of sortilin with fatty acid-binding protein 7 (FABP7), the intracellular carrier for PUFA in the brain. In the presence of apoE3, sortilin promotes functional expression of FABP7 and its ability to elicit lipid-dependent gene transcription. By contrast, apoE4 binding blocks sortilin-mediated sorting, causing catabolism of FABP7 and impairing lipid signaling. Reduced FABP7 levels in the brain of AD patients expressing apoE4 substantiate the relevance of these interactions for neuronal lipid homeostasis. Taken together, we document interaction of sortilin with mediators of extracellular and intracellular lipid transport that provides a mechanistic explanation for loss of a neuroprotective lipid metabolism in AD. [ABSTRACT FROM AUTHOR]

The therapeutic potential of fatty acid binding protein 4 (FABP4) is widely acknowledged. Currently, there are numerous clinical studies that indicate how fatty acid binding protein 4 inhibitors could be useful in the treatment of various diseases. To identify new and more potent inhibitors, we utilized a two-step computational approach to design novel structures. Through the use of this approach, we were able to identify a new class of FABP4 inhibitors (FABP4i IC50 2.97 to 23.18 µM) that are capable of inhibiting the activity of FABP4 as low as Arachidonic acid (FABP4i IC50 3.42 ± 0.54 µM). In this study, we present the detailed structural and biological evaluation, and the synthetic procedures of the new pyridazinone-based scaffold FABP4i.

Fatty acid binding protein-4 (FABP4) is not normally expressed in the liver but is induced in alcohol-dependent liver disease (ALD)). This study sought to identify mechanisms whereby ethanol (EtOH) metabolism alters triglyceride accumulation and FABP4 production. Human hepatoma cells which were stably transfected to express alcohol dehydrogenase (ADH) or cytochrome P4502E1 (CYP2E1) were exposed to EtOH in the absence/presence of inhibitors of ADH (4-methylpyrazole) or CYP2E1 (chlormethiazole). Cells were analyzed for free fatty acid (FFA) content and FABP4 mRNA, then culture medium assayed for FABP4 levels. Cell lysates were analyzed for AMP-activated protein kinase-α (AMPKα), Acetyl-CoA carboxylase (ACC), sterol regulatory element binding protein-1c (SREBP-1c), and Lipin-1β activity and localization in the absence/presence of EtOH and pharmacological inhibitors. CYP2E1-EtOH metabolism led to increased FABP4 mRNA/protein expression and FFA accumulation. Analysis of signaling pathway activity revealed decreased AMPKα activation and increased nuclear-SREBP-1c localization following CYP2E1-EtOH metabolism. The role of AMPKα-SREBP-1c in regulating CYP2E1-EtOH-dependent FFA accumulation and increased FABP4 was confirmed using pharmacological inhibitors and over-expression of AMPKα. Inhibition of ACC or Lipin-1β failed to prevent FFA accumulation or changes in FABP4 mRNA expression or protein secretion. These data suggest that CYP2E1-EtOH metabolism inhibits AMPKα phosphorylation to stimulate FFA accumulation and FABP4 protein secretion via an SREBP-1c dependent mechanism.

Fatty acid binding protein (FABP4) inhibitors are of synthetic and therapeutic interest and ongoing clinical studies indicate that they may be a promise for the treatment of cancer, as well as other diseases. As part of a broader research effort to develop more effective FABP4 inhibitors, we sought to identify new structures through a two-step computing assisted molecular design based on the established scaffold of a co-crystallized ligand. Novel and potent FABP4 inhibitors have been developed using this approach and herein we report the synthesis, biological evaluation and molecular docking of the 4-amino and 4-ureido pyridazinone-based series.

Fatty acid binding proteins (FABPs) are proteins found in the cytosol that contribute to disorders related to the cardiovascular system, including atherosclerosis and metabolic syndrome. Functionally, FABPs serve as intracellular lipid chaperones, interacting with hydrophobic ligands and mediating their transportation to sites of lipid metabolism. To date, nine unique members of the FABP family (FABP 1–9) have been identified and classified according to the tissue in which they are most highly expressed. In the literature, FABP3 has been shown to be a promising clinical biomarker for coronary and peripheral artery disease. Given the rising incidence of cardiovascular disease and its associated morbidity/mortality, identifying biomarkers for early diagnosis and treatment is critical. In this review, we highlight key discoveries and recent studies on the role of FABP3 in cardiovascular disorders, with a particular focus on its clinical relevance as a biomarker for peripheral artery disease.

• Fatty acid binding protein 7 (FABP7) is a regulator of cell metabolism and growth that is overexpressed in cancers. • FABP7 overexpression in tumours correlates with patient prognosis across many (but not all) cancers. • Genetic or pharmacological inhibition of FABP7 reduces tumour growth and promotes survival, and may represent a novel therapeutic strategy. Fatty acid binding protein 7 (FABP7) is an intracellular protein involved in the uptake, transportation, metabolism, and storage of fatty acids (FAs). FABP7 is upregulated up to 20-fold in multiple cancers, usually correlated with poor prognosis. FABP7 silencing or pharmacological inhibition suggest FABP7 promotes cell growth, migration, invasion, colony and spheroid formation/increased size, lipid uptake, and lipid droplet formation. Xenograft studies show that suppression of FABP7 inhibits tumour formation and tumour growth, and improves host survival. The molecular mechanisms involve promotion of FA uptake, lipid droplets, signalling [focal adhesion kinase (FAK), proto-oncogene tyrosine-protein kinase Src (Src), mitogen-activated protein kinase kinase/p-extracellular signal-regulated kinase (MEK/ERK), and Wnt/β-catenin], hypoxia-inducible factor 1-alpha (Hif1α), vascular endothelial growth factor A/prolyl 4-hydroxylase subunit alpha-1 (VEGFA/P4HA1), snail family zinc finger 1 (Snail1), and twist-related protein 1 (Twist1). The oncogenic capacity of FABP7 makes it a promising pharmacological target for future cancer treatments. [ABSTRACT FROM AUTHOR]

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, partly due to the lack of targeted therapy available. Cancer cells heavily reprogram their metabolism and acquire metabolic plasticity to satisfy the high-energy demand due to uncontrolled proliferation. Accumulating evidence shows that deregulated lipid metabolism affects cancer cell survival, and therefore we sought to understand the function of fatty acid binding protein 7 (FABP7), which is expressed predominantly in TNBC tissues. As FABP7 was not detected in the TNBC cell lines tested, Hs578T and MDA-MB-231 cells were transduced with lentiviral particles containing either FABP7 open reading frame or red fluorescent protein. During serum starvation, when lipids were significantly reduced, FABP7 decreased the viability of Hs578T, but not of MDA-MB-231, cells. FABP7-overexpressing Hs578T (Hs-FABP7) cells failed to efficiently utilize other available bioenergetic substrates such as glucose to sustain ATP production, which led to S/G2 phase arrest and cell death. We further showed that this metabolic phenotype was mediated by PPAR-α signaling, despite the lack of fatty acids in culture media, as Hs-FABP7 cells attempted to survive. This study provides imperative evidence of metabolic vulnerabilities driven by FABP7 via PPAR-α signaling.

Ifosfamide (IF) is a cytostatic that exhibits adverse nephrotoxic properties. Clinically, IF-induced nephrotoxicity takes various forms, depending on applied dose and length of treatment.

Aim. To study the association between a positive results of Heart-type fatty acid binding protein (h-FABP) test with the development of adverse outcomes during the year of observation in patients with non-ST elevation acute coronary syndrome (NSTE-ACS) depending on the type 2 diabetes mellitus (DM-2) presence.Material and methods. The study included 153 patients with NSTEACS hospitalized in the department of emergency cardiology in the period from March 2014 to January 2017. In addition to the standard examination, all patients underwent a qualitative analysis on the h-FABP in venous blood. Results. Kaplan–Meier estimator demonstrated a significant probability of a combined end point in patients with positive h-FABP, both with and without DM-2. H-FABP also acts as a marker for the development of adverse outcomes during the year after NSTE-ACS. Patients with adverse outcomes and type 2 diabetes mellitus had the highest frequency (100%) of positive test reactions.Conclusion. H-FABP positive test when admitted to hospital may be considered as a predictor of adverse long-term outcomes in patients with NSTE-ACS. That statistics is most significant for patients with DM-2.

Abstract Bile acids are natural detergents that aid in the absorption of dietary lipids. Fatty acid binding protein 6 (Fabp6) is a component of the bile acid recovery system that operates in the small intestine. The aim of this study was to determine if Fabp6 deficiency causes dietary fat malabsorption. Wild‐type and Fabp6‐deficient mice were fed a Western‐style diet (WSD) or a reference low‐fat diet (LFD) for 10 weeks. The body weight gain, bile acid excretion, fat excretion, energy metabolism, and major gut microbial phyla of the mice were assessed at the end of the controlled diet period. Fabp6−/− mice exhibited enhanced excretion of both bile acids and fat on the WSD but not on the LFD diet. Paradoxically, male Fabp6−/− mice, but not female Fabp6−/− mice, had greater adiposity despite increased fat excretion. Analysis of energy intake and of expenditure by indirect calorimetry revealed sex differences in physical activity level and respiratory quotient, but these did not account for the enhanced adiposity displayed by male Fabp6−/− mice. Analysis of stool DNA showed sex‐specific changes in the abundance of major phyla of bacteria in response to Fabp6 deficiency and WSD feeding. The results obtained indicate that the malabsorption of bile acids that occurs in Fabp6−/− mice is associated with dietary fat malabsorption on the high‐fat diet but not on the low‐fat diet. The WSD induced a sexually dimorphic increase in adiposity displayed by Fabp6−/− mice and sexually distinct pattern of change in gut microbiota composition.