Fatty acid-binding proteins--insights from genetic manipulations

The integral role of de novo lipogenesis in the preparation for seasonal dormancy

Animals can alter their body compositions in anticipation of dormancy to endure seasons with limited food availability. Accumulation of lipid reserves, mostly in the form of triglycerides (TAGs), is observed during the preparation for dormancy in diverse animals, including insects (diapause) and mammals (hibernation). However, the mechanisms involved in the regulation of lipid accumulation and the ecological consequences of failure to accumulate adequate lipid stores in preparation for animal dormancy remain understudied. In the broadest sense, lipid reserves can be accumulated in two ways: the animal either receives lipids directly from the environment or converts the sugars and amino acids present in food to fatty acids through de novo lipogenesis and then to TAGs. Here, we show that preparation for diapause in the Colorado potato beetle (Leptinotarsa decemlineata) involves orchestrated upregulation of genes involved in lipid metabolism with a transcript peak in 8- and 10-d-old diapause-destined insects. Regulation at the transcript abundance level was associated with the accumulation of substantial fat stores. Furthermore, the knockdown of de novo lipogenesis enzymes (ACCase and FAS-1) prolonged the preparatory phase, while the knockdown of fatty acid transportation genes shortened the preparatory phase. Our findings suggest a model in which the insects dynamically decide when to transition from the preparation phase into diapause, depending on the progress in lipid accumulation through de novo lipogenesis.

Silencing the FABP3 gene in insulin-secreting cells reduces fatty acid uptake and protects against lipotoxicity

BACKGROUND

Long-term exposure of pancreatic islets to fatty acids (FAs), common in obesity, metabolic syndrome, and type 2 diabetes, leads to a compensatory hyperactivity followed by inflammation, apoptosis, dysfunctional beta cells, and results in insulin dependence of the patient. Restriction of fatty uptake by islet beta cells may protect them from lipotoxicity.

PURPOSE

Pancreatic islet beta cells express the fatty acid binding protein 3 (FABP3) to bind FAs and to orchestrate lipid signals. Based on this, we investigated whether downregulation of FABP3, by Fabp3 silencing, might slow lipid metabolism and protect against lipotoxicity in insulin-secreting cells.

RESULTS

Neither Fabp3 silencing, nor overexpression affected the glucose-stimulated insulin secretion in absence of FAs. Fabp3 silencing decreased FA-uptake, lipid droplets formation, and the expression of the lipid accumulation-regulating gene Dgat1 in Ins1E cells. It reduced FA-induced inflammation by deactivation of NF-κB, which was associated with upregulation of IκBα and deactivation of the NF-κB p65 nuclear translocation, and the downregulation of the cytokines ILl-6, IL-1β, and TNFα. Ins1E cells were protected from the FA-induced apoptosis as assessed by different parameters including DNA degradation and cleaved caspase-3 immunoblotting. Furthermore, FABP3 silencing improved the viability, Pdx1 gene expression, and the insulin-secreting function in cells long-term cultured with palmitic acid. All results were confirmed by the opposite action rendered by FABP3 overexpression.

CONCLUSION

The present data reveals that pancreatic beta cells can be protected from lipotoxicity by inhibition of FA-uptake, intracellular utilization and accumulation. FABP3 inhibition, hence, may be a useful pharmaceutical approach in obesity, metabolic syndrome, and type 2 diabetes.

Concomitant decrease of E- and A-FABP expression predicts worse survival in urothelial bladder cancer patients

Non-muscle invasive bladder cancers (NMIBC) pTa-pT1 are depicted by a high risk of recurrence and/or progression with an unpredictable clinical evolution. Our aim was to identify, from the original resection specimen, tumors that will progress to better manage patients. We previously showed that A-FABP (Adipocyte- Fatty Acid Binding Protein) loss predicted NMIBC progression. Here we determined by immunohistochemistry the prognostic value of E-FABP (Epidermal-Fatty Acid Binding Protein) expression in 210 tumors (80 pTa, 75 pT1, 55 pT2-T4). Thus, E-FABP low expression was correlated with a high grade/stage, the presence of metastatic lymph nodes, and visceral metastases (p < 0.001). Unlike A-FABP in NMIBC, E-FABP low expression was not associated with RFS or PFS in Kaplan-Meier analysis. But patients of the overall cohort with a high E-FABP expression had a longer mOS (53.8 months vs. 29.3 months, p = 0.029). The immunohistochemical analysis on the same NMIBC tissue sections revealed that when A-FABP is absent, a high E-FABP expression is detected. E-FABP could compensate A-FABP loss. Interestingly, patients, whose original tumor presents both low E-FABP and negative A-FABP, had the worse survival, those maintaining the expression of both markers had better survival. To conclude, the combined evaluation of A- and E-FABP expression allowed to stratify patients with urothelial carcinoma for optimizing treatment and follow-up.

Tryptophan Promotes the Production of Xanthophyll Compounds in Yellow Abdominal Fat through HAAO

Abdominal fat, which in the past was often regarded as waste and discarded, has in recent years been used as a fat source to produce meat by-products. Yellow abdominal fat has higher economic value. Therefore, improving the color of abdominal fat plays an important role in improving the appearance of meat products. This study aimed to identify the contributors and the regulatory network involved in the formation of yellow and white color in abdominal fat. We found that four xanthophyll compounds were significantly different in yellow and white abdominal fat chicken, including zeaxanthin, lutein, canthaxanthin, and β-cryptoxanthin. There were 551 different and 8 common metabolites significantly correlated with these 4 xanthophyll compounds. Similarly, a total of 54 common genes were identified in 4 common related pathways (Complement and coagulation cascades, Metabolic pathways, PPAR signaling pathway, Carbon metabolism) of the 8 common metabolites. The high expression of HAAO in the yellow abdominal fat group leads to the degradation of tryptophan and its intermediate 5-hydroxyindole, and subsequently to the formation of the four xanthophyll compounds. This process is also regulated by tyrosine, kynurenine 3-monooxygenase (KMO), homogentisate 1, 2-dioxygenase (HGD), etc. Together, these findings show the effect of tryptophan on abdominal fat color, as well as a negative regulatory effect of HAAO and 5-hydroxyindole on the production of xanthophyll compounds involved in abdominal fat coloration.

The emerging role of fatty acid binding protein 7 (FABP7) in cancers

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.

Design, synthesis, and biological evaluation of first-in-class FABP1 inhibitors for the treatment of NASH

The fatty acid-binding protein 1 (FABP1) is a fatty acid transporter protein that is considered as an emerging target for metabolic diseases. Despite forceful evidence that the inhibition of FABP1 is essential for ameliorating NASH, pharmacological control and validation of FABP1 are hindered by a lack of relevant inhibitors as pharmacological tool. Therefore, the development of effective FABP1 inhibitors is a current focus of research. Herein, we firstly reported the comprehensive structure-activity relationship (SAR) study of novel FABP1 inhibitors derived from high throughput screening of our in-house library, which resulting in the identification of the optimal compound 44 (IC50 = 4.46 ± 0.54 μM). Molecular docking studies revealed that 44 forms stable hydrogen bonds with amino acids around the active pocket of FABP1. Moreover, 44 alleviated the typical histological features of fatty liver in NASH mice, including steatosis, lobular inflammation, ballooning and fibrosis. Additionally, 44 has been demonstrated to have lipid metabolism regulating, anti-oxidative stress and hepatoprotective properties. This study might be provided a promising insight into the field of NASH and inspiration for the development of FABP1 inhibitors.

Fatty acid-binding proteins 3, 7, and 8 bind cholesterol and facilitate its egress from lysosomes

Cholesterol from low-density lipoprotein (LDL) can be transported to many organelle membranes by non-vesicular mechanisms involving sterol transfer proteins (STPs). Fatty acid-binding protein (FABP) 7 was identified in our previous study searching for new regulators of intracellular cholesterol trafficking. Whether FABP7 is a bona fide STP remains unknown. Here, we found that FABP7 deficiency resulted in the accumulation of LDL-derived cholesterol in lysosomes and reduced cholesterol levels on the plasma membrane. A crystal structure of human FABP7 protein in complex with cholesterol was resolved at 2.7 Å resolution. In vitro, FABP7 efficiently transported the cholesterol analog dehydroergosterol between the liposomes. Further, the silencing of FABP3 and 8, which belong to the same family as FABP7, caused robust cholesterol accumulation in lysosomes. These two FABP proteins could transport dehydroergosterol in vitro as well. Collectively, our results suggest that FABP3, 7, and 8 are a new class of STPs mediating cholesterol egress from lysosomes.

Single-cell sequencing analysis and multiple machine-learning models revealed the cellular crosstalk of dendritic cells and identified FABP5 and KLRB1 as novel biomarkers for psoriasis

Background

Psoriasis is an immune-mediated disorder influenced by environmental factors on a genetic basis. Despite advancements, challenges persist, including the diminishing efficacy of biologics and small-molecule targeted agents, alongside managing recurrence and psoriasis-related comorbidities. Unraveling the underlying pathogenesis and identifying valuable biomarkers remain pivotal for diagnosing and treating psoriasis.

Methods

We employed a series of bioinformatics (including single-cell sequencing data analysis and machine learning techniques) and statistical methods to integrate and analyze multi-level data. We observed the cellular changes in psoriatic skin tissues, screened the key genes Fatty acid binding protein 5 (FABP5) and The killer cell lectin-like receptor B1 (KLRB1), evaluated the efficacy of six widely prescribed drugs on psoriasis treatment in modulating the dendritic cell-associated pathway, and assessed their overall efficacy. Finally, RT-qPCR, immunohistochemistry, and immunofluorescence assays were used to validate.

Results

The regulatory influence of dendritic cells (DCs) on T cells through the CD70/CD27 signaling pathway may emerge as a significant facet of the inflammatory response in psoriasis. Notably, FABP5 and KLRB1 exhibited up-regulation and co-localization in psoriatic skin tissues and M5-induced HaCaT cells, serving as potential biomarkers influencing psoriasis development.

Conclusion

Our study analyzed the impact of DC-T cell crosstalk in psoriasis, elucidated the characterization of two biomarkers, FABP5 and KLRB1, in psoriasis, and highlighted the promise and value of tofacitinib in psoriasis therapy targeting DCs.

Larvicidal activity of Acacia nilotica extracts against Culex pipiens and their suggested mode of action by molecular simulation docking

Mosquitoes are one of the deadliest and most hazardous animals on Earth, where they transmit several diseases that kill millions of people annually. There is an ongoing search almost everywhere in the world for more effective and contemporary ways to control mosquitoes other than pesticides. Phytochemicals are affordable, biodegradable biological agents that specialize in eliminating pests that represent a risk to public health. The effectiveness of Acacia nilotica methanol and aqueous leaf extracts against 4th instar larvae was evaluated. The results revealed that the methanol extract of A. nilotica had a noticeable influence on the mortality rate of mosquito larvae, especially at high concentrations. Not only did the mortality rate rise significantly, but the hatching of the mosquito eggs was potentially suppressed.Terpenes, fatty acids, esters, glycosides, pyrrolidine alkane, piperazine, and phenols were the most prevalent components in the methanol extract, while the aqueous extract of A. nilotica exclusively showed the presence of fatty acids. The insecticidal susceptibility tests of both aqueous and alcoholic extract of A. nilotica confirmed that the Acacia plant could serves as a secure and efficient substitute for chemical pesticides because of its promising effect on killing larvae and egg hatching delaying addition to their safety as one of the natural pesticides. Molecular docking study was performed using one of the crucial and life-controlling protein targets, fatty acid binding protein (FABP) and the most active ingredients as testing ligands to describe their binding ability. Most of the structurally related compounds to the co-crystallized ligand, OLA, like hexadecanoic acid furnished high binding affinity to the target protein with very strong and stable intermolecular hydrogen bonding and this is quite similar to OLA itself. Some other structural non-related compounds revealed extraordinarily strong binding abilities like Methoxy phenyl piperazine. Most of the binding reactivities of the majortested structures are due to high structure similarity between the positive control, OLA, and tested compounds. Such structure similarity reinforced with the binding abilities of some detected compounds in the A. nilotica extract could present a reasonable interpretation for its insecticidal activity via deactivating the FABP protein. The FABP4 enzyme inhibition activity was assessed for of both methanolic and aqueous of acacia plant extract and the inhibition results of methanol extract depicted noticeable potency if compared to orlistat, with half-maximal inhibitory concentration (IC50) of 0.681, and 0.535 µg/ml, respectively.

Global profiling of the proteome, phosphoproteome, and N-glycoproteome of protoscoleces and adult worms of Echinococcus granulosus

Introduction

Cystic echinococcosis (CE) is a chronic zoonosis caused by infection with the metacestode of the Echinococcus granulosus. A unique characteristic of E. granulosus protoscolex (PSC) is their ability to develop bidirectionally into an adult worm in the definitive host or a secondary hydatid cyst in the intermediate host. Furthermore, cestodes have a complex life cycle involving different developmental stages; however, the mechanisms underlying this development remain unknown. Several studies have demonstrated that certain matrix proteins undergo posttranslational modifications (PTMs), including phosphorylation and glycosylation, which have important regulatory effects on their functional properties.

Methods

Systematic analyses of the proteome, phosphorylated modified proteome, and glycosylated modified proteome of protoscoleces (PSCs) and adult worms were performed using a proteomic strategy. Data are available via ProteomeXchange with identifier PXD043166.

Results

In total, 6,407 phosphorylation sites and 1757 proteins were quantified. Of these, 2032 phosphorylation sites and 770 proteins were upregulated, and 2,993 phosphorylation sites and 1,217 proteins were downregulated in adult worms compared to PSCs. A total of 612 N-glycosylation sites were identified in the 392 N-glycoproteins. Of these, 355 N-glycosylation sites and 212 N-glycoproteins were quantified. Of these, 90 N-glycosylation sites and 64 N-glycoproteins were upregulated, and 171 N-glycosylation sites and 126 N-glycoproteins were downregulated in adult worms compared to PSCs. GO enrichment analysis indicated that the differentially expressed phosphoproteins were mainly enriched in the regulation of oxidoreduction coenzyme metabolic processes, myelin sheath, and RNA helicase activity, whereas the differentially expressed N-glycoproteins were enriched in the cellular response to unfolded proteins, endoplasmic reticulum lumen, and nucleic acid binding. KEGG enrichment analysis indicated that the differently expressed phosphoproteins were mainly enriched in RNA transport, hypertrophic cardiomyopathy (HCM), glycolysis/gluconeogenesis, HIF-1 signaling pathway and pyruvate metabolism. Differentially expressed N-glycoproteins were enriched in the PI3K-Akt signaling pathway, ECM-receptor interactions, and protein processing in the endoplasmic reticulum.

Discussion

To our knowledge, this study is the first global phosphoproteomic and N-glycoproteomic analysis of E. granulosus, which provides valuable information on the expression characteristics of E. granulosus and provides a new perspective to elucidate the role of protein phosphorylation and N-glycosylation in the development of E. granulosus.

On the Dynamic Mechanism of Long-Flexible Fatty Acid Binding to Fatty Acid Binding Protein: Resolving the Long-Standing Debate

Fatty acids (FAs) are one of the essential energy sources for physiological processes, and they play a vital role in regulating immune and inflammatory responses, promoting cell differentiation and apoptosis, and inhibiting tumor growth. These functions are carried out by FA binding proteins (FABPs) that recognize and transport FAs. Although the crystal structure of the FA-FABPs complex has long been characterized, the mechanism behind FA binding and dissociation from FABP remains unclear. This study employed conventional MD simulations and enhanced sampling technologies to investigate the atomic-scale complexes of heart fatty acid binding proteins and stearic acid (SA). The results revealed two primary pathways for the binding or dissociation of the flexible long-chain ligand, with the orientation of the SA carboxyl head during dissociation determining the chosen path. Conformational changes in the portal region of FABP during the ligand binding/unbinding were found to be trivial, and the overturn of the ″cap″ or the unfolding of the α2 helix was not required. This study resolves the long-standing debate on the binding mechanism of SA with the long-flexible tail to FABP, which significantly improves the understanding of the transport mechanism of FABPs and the development of related therapeutic agents.

Circulating Concentrations of Cathelicidin Anti-Microbial Peptide (CAMP) Are Increased during Oral Glucose Tolerance Test

Recent investigation has revealed the significant role of Cathelicidin antimicrobial peptide (CAMP) in infection defense and innate immunity processes in adipose tissue. Meanwhile, knowledge of its regulation and functions in metabolic contexts as an adipokine remains sparce. The present study investigated the postprandial regulation of circulating CAMP levels during oral glucose tolerance tests (OGTTs). Eighty-six metabolically healthy volunteers participated in a standardized 75 g-2 h-OGTT setting. The effects of exogenous glucose, insulin, and incretins on CAMP expression in human adipocyte culture (cell-line SGBS) were studied in vitro. CAMP concentrations in blood serum samples were measured by ELISA techniques and adipocyte gene expression levels were quantified by real-time PCR. Of note, base-line CAMP serum quantities were negatively correlated with HDL cholesterol levels as well as with the anti-inflammatory adipokine adiponectin. During the 2 h following glucose ingestion, a significant rise in circulating CAMP concentrations was observed in considerable contrast to reduced quantities of fatty acid binding proteins (FABP) 2 and 4 and dipeptidyl peptidase 4 (DPP4). In SGBS adipocytes, neither differing glucose levels nor insulin or incretin treatment significantly induced CAMP mRNA levels. According to our data, glucose represents a positive postprandial regulator of systemic CAMP. This effect apparently is not mediated by the regulatory impact of glucose metabolism on adipocyte CAMP expression.

MIR31HG, a potential lncRNA in human cancers and non-cancers

Long non-coding RNAs have recently attracted considerable attention due to their aberrant expression in human diseases. LncMIR31HG is a novel lncRNA that is abnormally expressed in multiple diseases and implicated in various stages of disease progression. A large proportion of recent studies have indicated that MIR31HG has biological functions by triggering various signalling pathways in the pathogenesis of human diseases, especially cancers. More importantly, the abnormal expression of MIR31HG makes it a potential biomarker in diagnosis and prognosis, as well as a promising target for treatments. This review aims to systematically summarize the gene polymorphism, expression profiles, biological roles, underlying mechanisms, and clinical applications of MIR31HG in human diseases.

Impact of Intracellular Lipid Binding Proteins on Endogenous and Xenobiotic Ligand Metabolism and Disposition

The family of intracellular lipid binding proteins (iLBPs) is comprised of 16 members of structurally related binding proteins that have ubiquitous tissue expression in humans. iLBPs collectively bind diverse essential endogenous lipids and xenobiotics. iLBPs solubilize and traffic lipophilic ligands through the aqueous milieu of the cell. Their expression is correlated with increased rates of ligand uptake into tissues and altered ligand metabolism. The importance of iLBPs in maintaining lipid homeostasis is well established. Fatty acid binding proteins (FABPs) make up the majority of iLBPs and are expressed in major organs relevant to xenobiotic absorption, distribution, and metabolism. FABPs bind a variety of xenobiotics including nonsteroidal anti-inflammatory drugs, psychoactive cannabinoids, benzodiazepines, antinociceptives, and peroxisome proliferators. FABP function is also associated with metabolic disease, making FABPs currently a target for drug development. Yet the potential contribution of FABP binding to distribution of xenobiotics into tissues and the mechanistic impact iLBPs may have on xenobiotic metabolism are largely undefined. This review examines the tissue-specific expression and functions of iLBPs, the ligand binding characteristics of iLBPs, their known endogenous and xenobiotic ligands, methods for measuring ligand binding, and mechanisms of ligand delivery from iLBPs to membranes and enzymes. Current knowledge of the importance of iLBPs in affecting disposition of xenobiotics is collectively described. SIGNIFICANCE STATEMENT: The data reviewed here show that FABPs bind many drugs and suggest that binding of drugs to FABPs in various tissues will affect drug distribution into tissues. The extensive work and findings with endogenous ligands suggest that FABPs may also alter the metabolism and transport of drugs. This review illustrates the potential significance of this understudied area.

Transcriptomic analysis of lipid metabolism in zebrafish offspring of parental long-term exposure to bisphenol A

Bisphenol A (BPA) is one of the most common environmental endocrine disruptor chemicals (EDCs) and exhibits reproductive, cardiovascular, immune, and neurodevelopmental toxic effects. The development of the offspring was examined in the present investigation to determine the cross-generational effects of long-term exposure of parental zebrafish to environmental concentrations of BPA (15 and 225 µg/L). Parents were exposed to BPA for 120 days, and their offspring were evaluated at 7 days after fertilization in BPA-free water. The offspring exhibited higher mortality, deformity, and heart rates, and showed significant fat accumulation in abdominal region. RNA-Seq data showed that more lipid metabolism-related KEGG pathways, such as the PPAR signaling pathway, adipocytokine signaling pathway, and ether lipid metabolism pathway were enriched in the 225 µg/L BPA-treated offspring compared to 15 µg/L BPA-treated offspring, indicating greater effects of high dose BPA on offspring lipid metabolism. Lipid metabolism-related genes implied that BPA is responsible for disrupting lipid metabolic processes in the offspring through increased lipid production, abnormal transport, and disruption of lipid catabolism. The present study will be helpful for further evaluation of the reproductive toxicity of environmental BPA to organisms and the subsequent parent-mediated intergenerational toxicity.

Comparison of physicochemical properties of sorghum extract by ethanol concentration and its anti-adipogenic effect in 3T3-L1 cells

Sorghum is a vital cereal source that has various phenolic compounds and potential health-promoting benefits. This study evaluated the phenolic content, antioxidant and anti-obesity effects of sorghum extract (SE) prepared using three solvent systems: 50% (SE50), 80% (SE80), and 100% (SE100) ethanol. The results showed that SE50 exhibited the highest total polyphenol and flavonoid content among the sorghum extracts using different ethanol concentrations as extraction solvents. In addition, SE50 showed significantly higher antioxidant capacity than the other extracts. Interestingly, SE50 significantly inhibited lipid accumulation in 3T3-L1 adipocytes; however, SE80 and SE100 had no beneficial effects. Moreover, SE50 significantly downregulated the mRNA expression levels of adipogenic genes (Cebpα, Pparγ, and Fabp4) and lipogenic genes (Srebp1c, Fas, and Scd1). These results suggest that SE50 is superior to other ethanol extracts in phenolic contents, antioxidant and anti-obesity activities, and it could be used as a nutraceutical for anti-obesity.

Importance of fatty acid binding proteins in cellular function and organismal metabolism

Fatty acid binding proteins (Fabps) are small soluble proteins that are abundant in the cytosol. These proteins are known to bind a myriad of small hydrophobic molecules and have been postulated to serve a variety of roles, yet their precise functions have remained an enigma over half a century of study. Here, we consider recent findings, along with the cumulative findings contributed by many laboratories working on Fabps over the last half century, to synthesize a new outlook for what functions Fabps serve in cells and organisms. Collectively, the findings illustrate that Fabps function as versatile multi-purpose devices serving as sensors, conveyors and modulators to enable cells to detect and handle a specific class of metabolites, and to adjust their metabolic capacity and efficiency.

Ferroptosis, Acyl Starvation, and Breast Cancer

To maintain their growth rate, cancer cells must secure a supply of fatty acids, which are necessary for building cell membranes and maintaining energy processes. This is one of the reasons why tissues with intensive fatty acid metabolism, such as the mammary gland, are more likely to develop tumors. One natural or induced defense process against cancer is ferroptosis, which interferes with normal fatty acid metabolism. This leads to the oxidation of polyunsaturated fatty acids, which causes a rearrangement of the metabolism and damages cell membranes. As a consequence of this oxidation, there is a shortage of normal polyunsaturated fatty acids, which disturbs the complicated metabolism of fatty acids. This imbalance in metabolism, resulting from the deficiency of properly structured fatty acids, is called, by these authors, "acyl starvation." When cancer cells are exposed to alternating hypoxia and reoxygenation, they often develop resistance to neoadjuvant therapies. Blocking the stearoyl-CoA desaturase - fatty acid-binding protein 4 - fatty acid translocase axis appears to be a promising pathway in the treatment of breast cancer. On the one hand, the inhibition of desaturase leads to the formation of toxic phospholipid hydroperoxides in ferroptosis, whereas on the other hand, the inhibition of fatty acid-binding protein 4 and translocase leads to a reduced uptake of fatty acids and disruption of the cellular transport of fatty acids, resulting in intracellular acyl starvation. The disruption in the metabolism of fatty acids in cancer cells may augment the effectiveness of neoadjuvant therapy. SIGNIFICANCE STATEMENT: Regulation of the metabolism of fatty acids in cancer cells seems to be a promising therapeutic direction. Studies show that the induction of ferroptosis in cancer cells, combined with use of neoadjuvant therapies, effectively inhibits the proliferation of these cells. We link the process of ferroptosis with apoptosis and SCD1-FABP4-CD36 axis and propose the term "acyl starvation" for the processes leading to FA deficiency, dysregulation of FA metabolism in cancer cells, and, most importantly, the appearance of incorrect proportions FAs.

Expression of key genes involved in lipid deposition in intramuscular adipocytes of sheep under high glucose conditions

The intramuscular fat (IMF) content in sheep is associated with IMF deposition, which is affected by intramuscular adipocyte hypertrophy. In this study, we established an in vitro high glucose model of intramuscular adipocytes of sheep to investigate the expression of cannabinoid receptor 1 (CB1) gene, fatty acid-binding protein 4 (FABP4) gene, lipid metabolism-associated genes (acetyl-CoA carboxylase [ACC], fatty acid synthase [FAS], and stearoyl-CoA desaturase 1 [SCD1]), and transcription factors (liver X receptor [LXRα]), sterol regulatory element-binding transcription factor 1 [SREBF-1], and carbohydrate-responsive element-binding protein [ChREBP]) as well as the changes in the lipid and triglyceride (TG) levels in intramuscular adipocytes. The results showed that the differentiated mature adipocytes had a spherical shape, and the number and volume of the lipid droplets gradually increased over time under high glucose conditions. The lipid and TG levels in intramuscular adipocytes of sheep continuously increased under high glucose conditions. Furthermore, CB1, FABP4, ACC, FAS, SCD1, LXRα, SREBF-1, and ChREBP were highly expressed under high glucose conditions, suggesting that the energetic nutrients also affect the expression of the CB1 gene, which works in coordination with lipid metabolism-associated genes and are beneficial for lipid deposition in the intramuscular adipocytes of sheep.

Role of FABP5 in T Cell Lipid Metabolism and Function in the Tumor Microenvironment

To evade immune surveillance, tumors develop a hostile microenvironment that inhibits anti-tumor immunity. Recent immunotherapy breakthroughs that target the reinvigoration of tumor-infiltrating T lymphocytes (TIL) have led to unprecedented success in treating some cancers that are resistant to conventional therapy, suggesting that T cells play a pivotal role in anti-tumor immunity. In the hostile tumor microenvironment (TME), activated T cells are known to mainly rely on aerobic glycolysis to facilitate their proliferation and anti-tumor function. However, TILs usually exhibit an exhausted phenotype and impaired anti-tumor activity due to the limited availability of key nutrients (e.g., glucose) in the TME. Given that different T cell subsets have unique metabolic pathways which determine their effector function, this review introduces our current understanding of T cell development, activation signals and metabolic pathways. Moreover, emerging evidence suggests that fatty acid binding protein 5 (FABP5) expression in T cells regulates T cell lipid metabolism and function. We highlight how FABP5 regulates fatty acid uptake and oxidation, thus shaping the survival and function of different T cell subsets in the TME.

SAR study on Novel truxillic acid monoester-Based inhibitors of fatty acid binding proteins as Next-Generation antinociceptive agents

Fatty acid binding protein 5 (FABP5) is a highly promising target for the development of analgesics as its inhibition is devoid of CB1R-dependent side-effects. The design and discovery of highly potent and FABP5-selective truxillic acid (TA) monoesters (TAMEs) is the primary aim of the present study. On the basis of molecular docking analysis, ca. 2,000 TAMEs were designed and screened in silico, to funnel down to 55 new TAMEs, which were synthesized and assayed for their affinity (Ki) to FABP5, 3 and 7. The SAR study revealed that the introduction of H-bond acceptors to the far end of the 1,1'-biphenyl-3-yl and 1,1'-biphenyl-2-yl ester moieties improved the affinity of α-TAMEs to FABP5. Compound γ-3 is the first γ-TAME, demonstrating a high affinity to FABP5 and competing with α-TAMEs. We identified the best 20 TAMEs based on the FABP5/3 selectivity index. The clear front runner is α-16, bearing a 2‑indanyl ester moiety. In sharp contrast, no ε-TAMEs made the top 20 in this list. However, α-19 and ε-202, have been identified as potent FABP3-selective inhibitors for applications related to their possible use in the protection of cardiac myocytes and the reduction of α-synuclein accumulation in Parkinson's disease. Among the best 20 TAMEs selected based on the affinity to FABP7, 13 out of 20 TAMEs were found to be FABP7-selective, with α-21 as the most selective. This study identified several TAMEs as FABP7-selective inhibitors, which would have potentially beneficial therapeutic effects in diseases such as Down's syndrome, schizophrenia, breast cancer, and astrocytoma. We successfully introduced the α-TA monosilyl ester (TAMSE)-mediated protocol to dramatically improve the overall yields of α-TAMEs. α-TAMSEs with TBDPS as the silyl group is isolated in good yields and unreacted α-TA/ α-MeO-TA, as well as disilyl esters (α-TADSEs) are fully recycled. Molecular docking analysis provided rational explanations for the observed binding affinity and selectivity of the FABP3, 5 and 7 inhibitors, including their α, γ and ε isomers, in this study.

Comparative transcriptome sequencing analysis of female and male Decapterus macrosoma

Sexual growth dimorphism is a common phenomenon in teleost fish and has led to many reproductive strategies. Growth- and sex-related gene research in teleost fish would broaden our understanding of the process. In this study, transcriptome sequencing of shortfin scad Decapterus macrosoma was performed for the first time, and a high-quality reference transcriptome was constructed. After identification and assembly, a total of 58,475 nonredundant unigenes were obtained with an N50 length of 2,266 bp, and 28,174 unigenes were successfully annotated with multiple public databases. BUSCO analysis determined a level of 92.9% completeness for the assembled transcriptome. Gene expression analysis revealed 2,345 differentially expressed genes (DEGs) in the female and male D. macrosoma, 1,150 of which were female-biased DEGs, and 1,195 unigenes were male-biased DEGs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that the DEGs were mainly involved in biological processes including protein synthesis, growth, rhythmic processes, immune defense, and vitellogenesis. Then, we identified many growth- and sex-related genes, including Igf, Fabps, EF-hand family genes, Zp3, Zp4 and Vg. In addition, a total of 19,573 simple sequence repeats (SSRs) were screened and identified from the transcriptome sequences. The results of this study can provide valuable information on growth- and sex-related genes and facilitate further exploration of the molecular mechanism of sexual growth dimorphism.

Proteomics analysis reveals promotion effect of 1α,25-dihydroxyvitamin D3 on mammary gland development and lactation of primiparous sows during gestation

1α,25(OH)₂VD₃ is the most active form of vitamin D₃ in animals, and it plays an important role in regulating mineral metabolism and reproduction. In this study, 140 crossbred gilts (Landrace × Yorkshire) were selected, randomly divided into four groups, and fed with a commercial diet supplemented with 0, 1, 2, and 4 μg/kg of 1α,25(OH)₂VD₃ in the form of 1α,25(OH)₂VD₃-glycosides. The mammary gland tissues were sampled from sows on day 114 of gestation. The production data of sows in each group were analyzed, and the colostrum quality was evaluated. Differentially abundant proteins (DAPs) in the mammary tissues were identified by tandem mass tag (TMT) technique and were verified by Western blot and parallel reaction monitoring (PRM). The results showed that 4 μg/kg 1α,25(OH)₂VD₃-glycosides significantly promoted the piglet birth weight, weaning weight, colostrum quality, and lactation ability of primiparous sows. The proteomics analysis showed that of the identified 53,118 peptides, 48,868 were unique peptides. A total of 5029 DAPs were identified, of which 4292 DAPs contained quantitative information. Our data indicated that 1α,25(OH)₂VD₃ was involved in the regulation of the mammary gland development and lactation in a dose-dependent manner through multiple pathways during gestation of primiparous sows. SIGNIFICANCE: The mammary gland is an important lactation organ of female mammals. Our research aims to reveal the effect of dietary supplementation with 1α,25(OH)₂VD₃ on mammary gland development and lactation of primiparous sow. This study identified potential signaling pathways and DAPs involved in regulating the mammary gland development and lactation in sows. Our findings provides theoretical basis for improving the fecundity of sows.

Effects of Elamipretide on Autophagy in Renal Cells of Pigs with Metabolic Syndrome

Autophagy eliminates excessive nutrients and maintains homeostasis. Obesity and metabolic syndrome (MetS) dysregulate autophagy, possibly partly due to mitochondria injury and inflammation. Elamipretide (ELAM) improves mitochondrial function. We hypothesized that MetS blunts kidney autophagy, which ELAM would restore. Domestic pigs were fed a control or MetS-inducing diet for 16 weeks. During the 4 last weeks, MetS pigs received subcutaneous injections of ELAM (0.1 mg/kg/day, MetS + ELAM) or vehicle (MetS), and kidneys were then harvested to measure protein expression of autophagy mediators and apoptosis. Systemic and renal venous levels of inflammatory cytokines were measured to calculate renal release. The function of isolated mitochondria was assessed by oxidative stress, energy production, and pro-apoptotic activity. MetS slightly downregulated renal expression of autophagy mediators including p62, ATG5-12, mTOR, and AMPK vs. control. Increased mitochondrial H₂O₂ production accompanied decreased ATP production, elevated apoptosis, and renal fibrosis. In MetS + ELAM, mito-protection restored autophagic protein expression, improved mitochondrial energetics, and blunted renal cytokine release and fibrosis. In vitro, mitoprotection restored mitochondrial membrane potential and reduced oxidative stress in injured proximal tubular epithelial cells. Our study suggests that swine MetS mildly affects renal autophagy, possibly secondary to mitochondrial damage, and may contribute to kidney structural damage in MetS.

Effect of theaflavin-3,3′-digallate on leptin-deficient induced nonalcoholic fatty liver disease might be related to lipid metabolism regulated by the Fads1/PPARδ/Fabp4 axis and gut microbiota

Nonalcoholic fatty liver disease (NAFLD), one of the risk factors for hepatitis, cirrhosis, and even hepatic carcinoma, has been a global public health problem. The polyphenol compound theaflavin-3,3′-digallate (TF3), mainly extracted from black tea, has been reported to produce an effect on hypoglycemic and antilipid deposition in vitro. In our study, we further investigated the function and novel mechanisms of TF3 in protecting NAFLD in vivo. By using leptin-deficient obese (ob/ob) mice with NAFLD symptoms, TF3 treatment prevented body weight and waistline gain, reduced lipid accumulation, and alleviated liver function injury, as well as decreased serum lipid levels and TG levels in livers in ob/ob mice, observing no side effects. Furthermore, the transcriptome sequencing of liver tissue showed that TF3 treatment corrected the expression profiles of livers in ob/ob mice compared with that of the model group. It is interesting to note that TF3 might regulate lipid metabolism via the Fads1/PPARδ/Fabp4 axis. In addition, 16S rRNA sequencing demonstrated that TF3 increased the abundance of Prevotellaceae_UCG-001, norank_f_Ruminococcaceae, and GCA-900066575 and significantly decreased that of Parvibacter. Taken together, the effect of TF3 on NAFLD might be related to lipid metabolism regulated by the Fads1/PPARδ/Fabp4 axis and gut microbiota. TF3 might be a promising candidate for NAFLD therapy.

FABP4 in obesity-associated carcinogenesis: Novel insights into mechanisms and therapeutic implications

The increasing prevalence of obesity worldwide is associated with an increased risk of various diseases, including multiple metabolic diseases, cardiovascular diseases, and malignant tumors. Fatty acid binding proteins (FABPs) are members of the adipokine family of multifunctional proteins that are related to fatty acid metabolism and are divided into 12 types according to their tissue origin. FABP4 is mainly secreted by adipocytes and macrophages. Under obesity, the synthesis of FABP4 increases, and the FABP4 content is higher not only in tissues but also in the blood, which promotes the occurrence and development of various cancers. Here, we comprehensively investigated obesity epidemiology and the biological mechanisms associated with the functions of FABP4 that may explain this effect. In this review, we explore the molecular mechanisms by which FABP4 promotes carcinoma development and the interaction between fat and cancer cells in obese circumstances here. This review leads us to understand how FABP4 signaling is involved in obesity-associated tumors, which could increase the potential for advancing novel therapeutic strategies and molecular targets for the systematic treatment of malignant tumors.

mTOR-FABP4 signal is activated in brain arteriovenous malformations in humans

Arteriovenous malformations (AVMs) are the most common types of cerebral vascular malformations, which are dynamic lesions with de novo growth potentials. The dysfunction of endothelial cells has been postulated to play a role in the pathogenesis of brain AVMs. mTOR-FABP4 signal enhances the angiogenic responses of endothelial cells and is not activated in the normal cerebral vasculature. Herein, we investigated the hypothesis that the mTOR-FABP4 signal may be activated in brain AVMs. The abundance of molecules in mTOR-FABP4 signal expression was detected by immunohistochemistry and Western blotting; special expressing cells were further characterized by double immunofluorescence using antibodies against various cell-specific markers. Next, several functional assays were performed to analyze the influence of the mTOR-FABP4 signal on proliferation, apoptosis, migration, and vascular tube formation of endothelial cells in human umbilical vein endothelial cells (HUVECs) using rapamycin and L-leucine. The expression of mTOR, p-mTOR, and FABP4 was increased in endothelial cells of human brain AVMs. Endothelial cell mTOR and p-mTOR expression were present in 70% and 55% of brain AVMs, respectively. Moreover, a population of FABP4-positive endothelial cells was detected in 80% of brain AVMs. The mTOR-FABP4 signal was activated and inhibited by L-leucine and rapamycin in HUVECs. The proliferation, apoptosis, migration, and vascular tube formation of endothelial cells could be inhibited by rapamycin. The mTOR-FABP4 signal was activated in human brain AVMs, and the mTOR-FABP4 signal was involved in proliferation, apoptosis, migration, and the vascular tube formation of endothelial cells. Taken together, whether rapamycin has therapeutic potential for treating human brain AVMs is worthy of further study. KEY MESSAGES : We confirmed that the mTOR- FABP4 pathway is activated in human brain arteriovenous malformations. We confirmed that mTOR signaling pathway affects endothelial cell function by regulating proliferation, migration, apoptosis, and tube formation of endothelial cell. Our study can provide theoretical support for mTOR pathway inhibitors in the treatment of human brain arteriovenous malformations.

Identification and Expression Analysis of an Interacting Protein (LvFABP) that Mediates Vibrio parahaemolyticus AHPND Toxin Action

Acute hepatopancreatic necrosis disease (AHPND) caused by Vibrio parahaemolyticus causing AHPND (VP_AHPND) is the most serious disease affecting shrimp farming. The PirA^vp and PirB^vp toxins of VP_AHPND are known virulence factors. However, the corresponding target protein in shrimp that mediates their action has not been identified. By screening yeast two-hybrid cDNA libraries from intestine, stomach, and hepatopancreas of Litopenaeus vannamei, the protein with the largest increase in gene expression in shrimp hepatopancreas in response to VP_AHPND challenge was identified and designated LvFABP. Analysis revealed high sequence homology of the LvFABP gene and a lipocalin/cytosolic fatty acid binding gene. Yeast two-hybrid pairwise analysis, GST-pull down assay, and far-western blot assay were performed to determine the interaction between LvFABP and PirB^vp. LvFABP was able to directly bind to PirB^vp. The expression of LvFABP in the hepatopancreas was significantly higher at P23 and P27 developmental stages of L. vannamei. RNA interference (RNAi) of LvFABP reduced the mortality, histopathological signs of AHPND in the hepatopancreas, and the number of virulent VP_AHPND bacteria in the intestine, stomach, and hepatopancreas after VP_AHPND challenge. We concluded that the LvFABP was involved in AHPND pathogenesis and acted as a VP_AHPND toxin interacting protein. This is the first identification of VP_AHPND toxin interacting protein from the shrimp digestive system by yeast two-hybrid library screening and were confirmed by in vitro protein interaction verification and in vivo challenge experiments. This study provides novel insight into the contributions of LvFABP towards AHPND pathogenesis in shrimp. The findings could inform AHPND preventative measures in shrimp farming.

Intestinal fatty acid binding protein: A rising therapeutic target in lipid metabolism

Fatty acid binding proteins (FABPs) are key proteins in lipid transport, and the isoforms are segregated according to their tissue origins. Several isoforms, such as adipose-FABP and epidermal-FABP, have been shown to participate in multiple pathologic processes due to their ubiquitous expression. Intestinal fatty acid binding protein, also termed FABP2 or I-FABP, is specifically expressed in the small intestine. FABP2 can traffic lipids from the intestinal lumen to enterocytes and bind superfluous fatty acids to maintain a steady pool of fatty acids in the epithelium. As a lipid chaperone, FABP2 can also carry lipophilic drugs to facilitate targeted transport. When the integrity of the intestinal epithelium is disrupted, FABP2 is released into the circulation. Thus, it can potentially serve as a clinical biomarker. In this review, we discuss the pivotal role of FABP2 in intestinal lipid metabolism. We also summarize the molecular interactions that have been reported to date, highlighting the clinical prospects of FABP2 research.

Function of lipid binding proteins of parasitic helminths: still a long road

Infections with parasitic helminths cause severe debilitating and sometimes lethal diseases in humans and domestic animals on a global scale. Unable to synthesize de novo their own fatty acids and sterols, helminth parasites (nematodes, trematodes, cestodes) rely on their hosts for their supply. These organisms produce and secrete a wide range of lipid binding proteins that are, in most cases, structurally different from the ones found in their hosts, placing them as possible novel therapeutic targets. In this sense, a lot of effort has been made towards the structure determination of these proteins, but their precise function is still unknown. In this review, we aim to present the current knowledge on the functions of LBPs present in parasitic helminths as well as novel members of this highly heterogeneous group of proteins.

Fatty Acid Metabolism in Ovarian Cancer: Therapeutic Implications

Ovarian cancer is the most malignant gynecological tumor. Previous studies have reported that metabolic alterations resulting from deregulated lipid metabolism promote ovarian cancer aggressiveness. Lipid metabolism involves the oxidation of fatty acids, which leads to energy generation or new lipid metabolite synthesis. The upregulation of fatty acid synthesis and related signaling promote tumor cell proliferation and migration, and, consequently, lead to poor prognosis. Fatty acid-mediated lipid metabolism in the tumor microenvironment (TME) modulates tumor cell immunity by regulating immune cells, including T cells, B cells, macrophages, and natural killer cells, which play essential roles in ovarian cancer cell survival. Here, the types and sources of fatty acids and their interactions with the TME of ovarian cancer have been reviewed. Additionally, this review focuses on the role of fatty acid metabolism in tumor immunity and suggests that fatty acid and related lipid metabolic pathways are potential therapeutic targets for ovarian cancer.

Identification of Diagnostic Biomarkers Associated with Stromal and Immune Cell Infiltration in Fatty Infiltration After Rotator Cuff Tear by Integrating Bioinformatic Analysis and Machine-Learning

Purpose

The present study aimed to explore potential diagnostic biomarkers for fatty infiltration (FI) of the rotator cuff muscles after rotator cuff tear (RCT) and investigate the influence of stromal and immune cell infiltration on this pathology.

Methods

The GSE130447 and GSE103266 datasets were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified, and gene set enrichment analyses were performed by R software. Two machine learning algorithms, random forest and multiple support vector machine recursive feature elimination (mSVM-RFE), were used to screen candidate biomarkers. The diagnostic value of the screened biomarkers was further validated by the area under the ROC curve (AUC) in the GSE103266 dataset. Murine microenvironment cell population counter (mMCP-counter) method was employed to estimate stromal and immune cell infiltration of FI. The correlation between biomarkers and infiltrated immune and stromal cell subsets was further analyzed.

Results

A total of 2123 DEGs were identified. The identified DEGs were predominantly linked to immune system process, extracellular matrix organization and PPAR signalling pathway. FABP5 (AUC = 0.958) and MGP (AUC = 1) were screened as diagnostic biomarkers of FI. Stromal and immune cell infiltration analysis showed that monocytes, mast cells, vessels, endothelial cells and fibroblasts may be related to the process of FI. FABP5 and MGP were positively correlated with vessels whereas negatively correlated with monocytes and mast cells.

Conclusion

FABP5 and MGP can serve as diagnostic biomarkers of FI after RCT, and stromal and immune cell infiltration may play a crucial role in this pathology.

Dysfunction of metabolic activity of bone marrow mesenchymal stem cells in aged mice

Objectives

Evidences have suggested that the metabolic function is the key regulator to the fate of MSCs, but its function in senescence of MSC and the underlying mechanism is unclear. Therefore, the purpose of this study was to investigate the metabolic activity of MSCs and its possible mechanism during aging.

Materials and Methods

We used the Seahorse XF24 Analyzer to understand OCR and ECAR in BMSCs and used RT‐PCR to analyze the gene expression of mitochondrial biogenesis and key enzymes in glycolysis. We analyzed BMSC mitochondrial activity by MitoTracker Deep Red and JC‐1 staining, and detected NAD+/NADH ratio and ATP levels in BMSCs. Microarray and proteomic analyses were performed to detect differentially expressed genes and proteins in BMSCs. The impact of aging on BMSCs through mitochondrial electron transport chain (ETC) was evaluated by Rotenone and Coenzyme Q10.

Results

Our results demonstrated that the oxidative phosphorylation and glycolytic activity of BMSCs in aged mice were significantly decreased when compared with young mice. BMSCs in aged mice had lower mitochondrial membrane potential, NAD+/NADH ratio, and ATP production than young mice. FABP4 may play a key role in BMSC senescence caused by fatty acid metabolism disorders.

Conclusions

Taken together, our results indicated the dysfunction of the metabolic activity of BMSCs in aged mice, which would play the important role in the impaired biological properties. Therefore, the regulation of metabolic activity may be a potential therapeutic target for enhancing the regenerative functions of BMSCs.

Structural and Dynamic Determinants of Molecular Recognition in Bile Acid-Binding Proteins

Disorders in bile acid transport and metabolism have been related to a number of metabolic disease states, atherosclerosis, type-II diabetes, and cancer. Bile acid-binding proteins (BABPs), a subfamily of intracellular lipid-binding proteins (iLBPs), have a key role in the cellular trafficking and metabolic targeting of bile salts. Within the family of iLBPs, BABPs exhibit unique binding properties including positive binding cooperativity and site-selectivity, which in different tissues and organisms appears to be tailored to the local bile salt pool. Structural and biophysical studies of the past two decades have shed light on the mechanism of bile salt binding at the atomic level, providing us with a mechanistic picture of ligand entry and release, and the communication between the binding sites. In this review, we discuss the emerging view of bile salt recognition in intestinal- and liver-BABPs, with examples from both mammalian and non-mammalian species. The structural and dynamic determinants of the BABP-bile–salt interaction reviewed herein set the basis for the design and development of drug candidates targeting the transcellular traffic of bile salts in enterocytes and hepatocytes.

High Serum FABP4 Levels are Negatively Associated with the Reversion from Prediabetes to Normal Glucose Tolerance: A 2-Year Retrospective Cohort Community Study

OBJECTIVE

To explore the relationship between the level of fatty acid-binding protein 4 (FABP4) and reversion from prediabetes to normal glucose tolerance (NGT).

METHODS

A two-year retrospective cohort study was conducted on 398 participants with complete information. These 398 participants were divided into an NGT group and an abnormal glucose metabolism (AGM) group after 2 years of follow-up. The baseline level of FABP4 was determined, and the role of FABP4 in predicting reversion from prediabetes to NGT was investigated using an unconditional logistic regression model.

RESULTS

Over the two-year follow-up period, 37.4% (149/398) of the participants reverted from prediabetes to NGT. The participants with AGM had a higher baseline level of FABP4 than those with NGT. The baseline level of FABP4 was significantly negatively correlated with reversion from prediabetes to NGT. After adjusting for age, sex, body mass index and waist-to-hip ratio, the level of fasting blood glucose (FBG) [odds ratio (OR) 0.336, 95% confidence interval (CI) (0.196-0.576)], 2-h post-challenge blood glucose (2hBG) [OR 0.697, 95% CI (0.581-0.837)], and FABP4 [OR 0.960, 95% CI (0.928-0.993)] at baseline were significant independent predictors of reversion from prediabetes to NGT. The area under the curve (AUC) value of the receiver operating characteristic curve for FABP4 was 0.605 (95% CI: 0.546-0.665), and the AUC for FABP4 combined with FBG and 2hBG was 0.716 (95% CI: 0.663-0.769).

CONCLUSION

A higher baseline level of FABP4 was positively correlated with an adverse profile of diabetes risk factors and negatively correlated with reversion from prediabetes to NGT. FABP4, FBG and 2hBG were predictors of reversion from prediabetes to NGT.

Adipokines, Hepatokines and Myokines: Focus on Their Role and Molecular Mechanisms in Adipose Tissue Inflammation

Chronic low-grade inflammation in adipose tissue (AT) is a hallmark of obesity and contributes to various metabolic disorders, such as type 2 diabetes and cardiovascular diseases. Inflammation in ATs is characterized by macrophage infiltration and the activation of inflammatory pathways mediated by NF-κB, JNK, and NLRP3 inflammasomes. Adipokines, hepatokines and myokines - proteins secreted from AT, the liver and skeletal muscle play regulatory roles in AT inflammation via endocrine, paracrine, and autocrine pathways. For example, obesity is associated with elevated levels of pro-inflammatory adipokines (e.g., leptin, resistin, chemerin, progranulin, RBP4, WISP1, FABP4, PAI-1, Follistatin-like1, MCP-1, SPARC, SPARCL1, and SAA) and reduced levels of anti-inflammatory adipokines such as adiponectin, omentin, ZAG, SFRP5, CTRP3, vaspin, and IL-10. Moreover, some hepatokines (Fetuin A, DPP4, FGF21, GDF15, and MANF) and myokines (irisin, IL-6, and DEL-1) also play pro- or anti-inflammatory roles in AT inflammation. This review aims to provide an updated understanding of these organokines and their role in AT inflammation and related metabolic abnormalities. It serves to highlight the molecular mechanisms underlying the effects of these organokines and their clinical significance. Insights into the roles and mechanisms of these organokines could provide novel and potential therapeutic targets for obesity-induced inflammation.

Transcriptomic analysis of thigh muscle of Lueyang black-bone chicken in free-range and caged feeding

Lueyang black-bone chicken is free-range in hilly areas and has unique genetic characteristics and excellent muscle quality. However, the molecular mechanisms of breeding mode influence growth and meat quality in Lueyang black-bone chicken are still unclear. Here we analyzed the meat quality and transcriptome data of thigh muscle by comparing free-range and caged modes at the age of 60 and 120 days in Lueyang black-boned chicken. The results demonstrated that the free-range mode could improve the pH value, tenderness, and reducing the hardness of the thigh muscle. Intramuscular fat (IMF) content of the thigh muscle was markedly higher in the caged chickens compared with free-range animals at the age of 60 days. Functional pathway analysis illustrated that tight junction signaling was associated with the formation of slow-twitch fibers in free-range chickens at age of 120 days. All research data proved that the free-range mode could improve muscle quality by promoting the formation of slow-twitch fibers and IMF in thigh muscle in Lueyang black-bone chicken. Based on the animal benefit and healthy, the free-range feeding should be considered during the breeding process of broiler chicken. The results provide good knowledge of the functional molecular mechanisms associated with muscle quality in Lueyang black-bone chicken.

The Involvement of TRIB3 and FABP1 and Their Potential Functions in the Dynamic Process of Gastric Cancer

Background: Dysregulated expression of TRIB3 and FABP1 have been previously observed in human cancer tissues. However, there are little information as to their expression change in dynamic gastric diseases and the functional roles.

Methods: Tissues from a total of 479 patients, including 89 GS, 102 IM-GA, 144 EGC, and 144 AGC were collected. The protein expressions of TRIB3 and FABP1 were detected by immunohistochemical staining. Meanwhile, the potential functions of TRIB3 and FABP1 in GC were further analyzed by R software and some internet public databases, such as TCGA and DAVID.

Results: During this multi-stage process that go through GS to EGC, the expression trend of TRIB3 and FABP1 protein was GS > IM-GA > EGC. Besides, the expression of TRIB3 protein continued to decrease in AGC, while the expression of FABP1 was abnormally increased. Hp infection was significantly associated with the decreased expression of TRIB3 and FABP1. In addition, the diagnostic efficiency of the combination of these two indicators to diagnose EGC was higher than that of a single indicator. Survival analysis showed that higher expression of TRIB3 or FABP1 could indicate a better prognosis of GC. The protein expressions of TRIB3 and FABP1 were significantly positively correlated. Moreover, CEACAM5 and PRAP1 were positively correlated with both TRIB3 and FABP1 expressions, while GABRP and THBS4 were negatively correlated. The macrophages M0 infiltration was positively correlated with both TRIB3 and FABP1 expressions.

Conclusion: The protein expressions of TRIB3 and FABP1 gradually decreased with the gastric disease progress, and was positively correlated. Hp infection may reduce the protein expression of TRIB3 and FABP1. Combing TRIB3 and FABP1 expressions can improve the diagnostic efficiency for EGC. Either a high expression of TRIB3 or FABP1 indicates a better prognosis for GC. TRIB3 and FABP1 may interact with CEACAM5, PRAP1, GABRP and THBS4, and affect tumor immune microenvironment by regulating immune cells, and participate in the development and progression of GC.

SNPs in miRNAs and Target Sequences: Role in Cancer and Diabetes

miRNAs are fascinating molecular players for gene regulation as individual miRNA can control multiple targets and a single target can be regulated by multiple miRNAs. Loss of miRNA regulated gene expression is often reported to be implicated in various human diseases like diabetes and cancer. Recently, geneticists across the world started reporting single nucleotide polymorphism (SNPs) in seed sequences of miRNAs. Similarly, SNPs are also reported in various target sequences of these miRNAs. Both the scenarios lead to dysregulated gene expression which may result in the progression of diseases. In the present paper, we explore SNPs in various miRNAs and their target sequences reported in various human cancers as well as diabetes. Similarly, we also present evidence of these mutations in various other human diseases.

Effect of Betaine Diet on Growth Performance, Carcass Quality and Fat Deposition in Finishing Ningxiang Pigs

Simple Summary

Excessive fat deposit is one of the major problems in finishing Ningxiang pigs, and adversely affects the breeding. The study aimed to investigate the effects of diet with betaine supplementation (basal diet + 0.2% betaine) on the growth performance, slaughter performance, meat quality and the genes expression related to fat deposition in finishing Ningxiang pigs. The results indicated that diet with betaine supplementation decreased back fat thickness and fat percentage, and increased the lean meat percentage as well. In addition, it reduced the fat deposition by regulating the genes expression. These findings provided a reference for breeding Ningxiang pigs.

Abstract

The present study was conducted to investigate the effects of diet with betaine supplementation on the growth performance, carcass quality and fat deposition in finishing Ningxiang pigs. A total of 24 Ningxiang pigs (43.6 ± 5.34 kg of average body weight) was randomly divided into two groups, with 6 replicates per treatment and 2 pigs per replicate. The treatments included a control group (basal diet) and a test group (basal diet + 0.2% betaine). The whole trial lasted 81 days. At the end of the experiment, one pig (close to the average body weight of all experimental pigs) per replicate was slaughtered to determine the carcass traits, meat quality and the mRNA expression levels of genes relate to fat deposition (one pig per replicate was randomly selected and fasted for 12 h, n = 6). Results indicated that growth performance was not changed with betaine supplementation. However, dietary with betaine supplementation decreased back fat thickness and fat percentage, and increased the lean meat percentage as well (p < 0.05). In addition, diet with betaine supplementation reduced drip loss, water loss, cooking loss, shear force and b × 24 h value of meat (p < 0.05). There was no difference in total moisture, ether extract and crude protein of longissimus thoracis between the control and test group. Dietary with betaine supplementation decreased ether extract and total cholesterol (p < 0.05) in liver. Dietary with betaine supplementation upregulated the mRNA expression levels of adipose triglyceride lipase (ATGL) and sirtuin 1 (Sirt1), while downregulated the mRNA expression levels of fatty acid synthase (FAS) and acetyl CoA carboxylase (ACC) in subcutaneous fat of back (p < 0.05). Besides, dietary with betaine supplementation upregulated the fatty acid binding protein 4 (FABP4) mRNA expression of longissimus thoracis in finishing Ningxiang pigs (p < 0.05). These results showed that diet supplemented with betaine could improve the slaughtering performance and meat quality, and regulate the genes expression to affect the fat deposition in finishing Ningxiang pigs.

Expression Profiles and Prognostic Value of FABPs in Colorectal Adenocarcinomas

Colorectal cancer (CRC) is one of the world's leading causes of cancer-related deaths; thus, it is important to detect it as early as possible. Obesity is thought to be linked to a large rise in the CRC incidence as a result of bad dietary choices, such as a high intake of animal fats. Fatty acid-binding proteins (FABPs) are a set of molecules that coordinate intracellular lipid responses and are highly associated with metabolism and inflammatory pathways. There are nine types of FABP genes that have been found in mammals, which are FABP1-7, FABP9, and FABP12. Each FABP gene has its own roles in different organs of the body; hence, each one has different expression levels in different cancers. The roles of FABP family genes in the development of CRC are still poorly understood. We used a bioinformatics approach to examine FABP family gene expression profiles using the Oncomine, GEPIA, PrognoScan, STRING, cBioPortal, MetaCore, and TIMER platforms. Results showed that the FABP6 messenger (m)RNA level is overexpressed in CRC cells compared to normal cells. The overexpression of FABP6 was found to be related to poor prognosis in CRC patients' overall survival. The immunohistochemical results in the Human Protein Atlas showed that FABP1 and FABP6 exhibited strong staining in CRC tissues. An enrichment analysis showed that high expression of FABP6 was significantly correlated with the role of microRNAs in cell proliferation in the development of CRC through the insulin-like growth factor (IGF) signaling pathway. FABP6 functions as an intracellular bile-acid transporter in the ileal epithelium. We looked at FABP6 expression in CRC since bile acids are important in the carcinogenesis of CRC. In conclusion, high FABP6 expression is expected to be a potential biomarker for detecting CRC at the early stage.

Serum biomarkers of isoniazid-induced liver injury: Aminotransferases are insufficient, and OPN, L-FABP and HMGB1 can be promising novel biomarkers

Isoniazid (INH)-induced liver injury is a great challenge for tuberculosis treatment. Existing biomarkers cannot accurately determine the occurrence of this injury in the early stage. Therefore, developing early specific sensitive biomarkers of INH-induced liver injury is urgent. A rat model of liver injury was established with gastric infusion of INH or INH plus rifampicin (RFP). We examined seven potential novel serum biomarkers, namely, glutamate dehydrogenase (GLDH), liver-fatty acid-binding protein (L-FABP), high-mobility group box-1 (HMGB1), macrophage colony-stimulating factor receptor (MCSF1R), osteopontin (OPN), total cytokeratin 18 (K18), and caspase-cleaved cytokeratin-18 (ccK18), to evaluate their sensitivity and specificity on INH-induced liver injury. With the increase of drug dosage, combining with RFP and prolonging duration of administration, the liver injury was aggravated, showing as decreased weight of the rats, upgraded liver index and oxidative stress level, and histopathological changes of liver becoming marked. But the activity of serum aminotransferases decreased significantly. The area under the curve (AUC) of receiver-operating characteristic (ROC) curve of OPN, L-FABP, HMGB1, MCSF1R, and GLDH was 0.88, 0.87, 0.85, 0.71, and 0.70 (≥0.7), respectively, and 95% confidence interval of them did not include 0.5, with statistical significance, indicating their potential abilities to become biomarkers of INH-induced liver injury. In conclusion, we found traditional biomarkers ALT and AST were insufficient to discover the INH-induced liver injury accurately and OPN, L-FABP, and HMGB1 can be promising novel biomarkers.

Effects of sublethal concentration of metamifop on hepatic lipid metabolism in adult zebrafish (Danio rerio)

Metamifop (MET) is an effective herbicide that has been extensively used in paddy fields. Previous research demonstrated that MET was highly toxic to zebrafish embryos, and this threat has caused great concern; moreover, 0.40 mg/L MET elevated the hepatosomatic index (HSI) in adult zebrafish without lethal effect after 21 d of exposure. In this study, we further determined the detailed impacts of MET on adult zebrafish at sublethal concentrations (0.025, 0.10 and 0.40 mg/L). We found that 0.40 mg/L MET caused liver injury by increasing the activity of aspartate aminotransferase and alanine aminotransferase in plasma, the content of interleukin-1β, IL-6, tumor necrosis factor-α, and mRNA expression level of genes associated with inflammatory response in liver of adult zebrafish. The hepatic triglyceride (TG), free fatty acid and fatty acid synthase levels were significantly elevated in 0.40 mg/L MET-treated group (1.55-, 2.20- and 2.30-fold, respectively), and the transcript of lipid accumulation-related genes (fabp10, fas, acc, chrebp, dagt2 and agpat4) were upregulated. Meanwhile, the total cholesterol content was decreased by 0.48-fold, bile acid level was increased by 2.44-fold, and levels of cholesterol metabolism-related genes (apoa-1a, hmgcra, cyp51, dhcr7 and cyp7a1) were increased, suggesting cholesterol metabolism disorder occurred in zebrafish. Furthermore, analysis of lipidomics revealed that 0.40 mg/L MET significantly increased the abundance of 91 lipids, which mainly belonged to TG lipid class and were enriched in pathways of glycerolipid metabolism, cholesterol metabolism, etc. These results suggested that MET exposure at sublethal concentrations would induce hepatic inflammation and lipid metabolism disorders in adult zebrafish.

Tardigrade Secretory-Abundant Heat-Soluble Protein Has a Flexible β-Barrel Structure in Solution and Keeps This Structure in Dehydration

Secretory-abundant heat-soluble (SAHS) proteins are unique heat-soluble proteins of Tardigrada and are believed to play an essential role in anhydrobiosis, a latent state of life induced by desiccation. To investigate the dynamic properties, molecular dynamics (MD) simulations of a SAHS protein, RvSAHS1, were performed in solution and under dehydrating conditions. For comparison purposes, MD simulations of a human liver-type fatty-acid binding protein (LFABP) were performed in solution. Furthermore, high-speed atomic force microscopy observations were conducted to ascertain the results of the MD simulations. Three properties of RvSAHS1 were found as follows. (1) The entrance region of RvSAHS1 is more flexible and can be more extensive in solutions compared with that of a human LFABP because there is no salt bridge between the βD and βE strands. (2) The intrinsically disordered domain in the N-terminal region significantly fluctuates and can form an amphiphilic α-helix. (3) The size of the entrance region gets smaller along with dehydration, keeping the β-barrel structure. Overall, the obtained results provide atomic-level dynamics of SAHS proteins.

Epigenetic modifications underlie the differential adipogenic potential of preadipocytes derived from human subcutaneous fat tissue

AIM

Ceiling culture-derived preadipocytes (ccdPAs) and adipose-derived stem cells (ASCs) can be harvested from human subcutaneous fat tissue using the specific gravity method. Both cell types possess a similar spindle shape without lipid droplets. We previously reported that ccdPAs have a higher adipogenic potential than ASCs, even after a 7-week culture. We performed a genome-wide epigenetic analysis to examine the mechanisms contributing to the adipogenic potential differences between ccdPAs and ASCs.

MATERIALS AND METHODS

Methylation analysis of cytosines followed by guanine (CpG) using a 450K BeadChip was performed on human ccdPAs and ASCs isolated from three metabolically healthy females. Chromatin immunoprecipitation sequencing (ChIP-seq) was performed to evaluate trimethylation at lysine 4 of histone 3 (H3K4me3).

RESULTS

Unsupervised machine learning using t-distributed stochastic neighbor embedding (tSNE) to interpret 450,000-dimensional methylation assay data showed that the cells were divided into ASC and ccdPA groups. In KEGG pathway analysis of 1,543 genes with differential promoter CpG methylation, the peroxisome proliferator-activated receptor (PPAR) and adipocytokine signaling pathways ranked in the top 10 pathways. In the PPAR gamma gene, H3K4me3 peak levels were higher in ccdPAs than in ASCs, whereas promoter CpG methylation levels were significantly lower in ccdPAs than in ASCs. Similar differences in promoter CpG methylation were also seen in the fatty acid-binding protein 4 (FABP4) and leptin genes.

CONCLUSION

We analyzed the epigenetic status of adipogenesis-related genes as a potential mechanism underlying the differences in adipogenic differentiation capability between ASCs and ccdPAs.

Dietary iron overload mitigates atherosclerosis in high-fat diet-fed apolipoprotein E knockout mice: Role of dysregulated hepatic fatty acid metabolism

The atherosclerosis "iron hypothesis" generates a fair amount of debate since it has been proposed. Here, we revisited the "iron hypothesis" by examining whether dietary iron overload would intensify iron deposition in plaques and thus lead to further exacerbation of atherosclerosis in apolipoprotein E knockout (ApoE KO) mice. ApoE KO mice were fed either a normal chow diet (ND) or a high fat diet (HFD) supplemented with or without 2% carbonyl iron (Fe) for 16 weeks. However, contrary to our assumption, dietary iron overloading did not intensify, but rather diminished the atherosclerotic lesion area by 65.3%, which was accompanied by significantly decreased serum total cholesterol, triglyceride and low-density lipoprotein cholesterol contents, together with hepatic lipid accumulation decline, despite the evident existence of aortic iron accumulation and the typical signs of iron overload in ApoE KO mice. Using isobaric tag for absolute quantification (iTRAQ) proteomics approach, hepatic CD36 and fatty acid binding proteins-mediated fatty acid (FA) uptake and trafficking impairment were identified as the key potential pathomechanisms by which iron overload diminishes atherosclerotic lesions. Furthermore, downstream hepatic FA de novo biosynthesis was enhanced and FA oxidation was inhibited to compensate for the FA deficiency triggered by iron overload-impaired fatty acid uptake and trafficking. Our findings suggested that dietary iron overload is not atherogenic in ApoE KO mice, and more research efforts are warranted to revisit the "iron hypothesis" of atherosclerosis.

De Novo Sequencing and High-Contiguity Genome Assembly of Moniezia expansa Reveals Its Specific Fatty Acid Metabolism and Reproductive Stem Cell Regulatory Network

Moniezia expansa (M. expansa) parasitizes the small intestine of sheep and causes inhibited growth and development or even death. Being globally distributed, it causes considerable economic losses to the animal husbandry industry. Here, using Illumina, PacBio and BioNano techniques, we obtain a high-quality genome assembly of M. expansa, which has a total length of 142 Mb, a scaffold N50 length of 7.27 Mb and 8,104 coding genes. M. expansa has a very high body fat content and a specific type of fatty acid metabolism. It cannot synthesize any lipids due to the loss of some key genes involved in fatty acid synthesis, and it may can metabolize most lipids via the relatively complete fatty acid β-oxidation pathway. The M. expansa genome encodes multiple lipid transporters and lipid binding proteins that enable the utilization of lipids in the host intestinal fluid. Although many of its systems are degraded (with the loss of homeobox genes), its reproductive system is well developed. PL10, AGO, Nanos and Pumilio compose a reproductive stem cell regulatory network. The results suggest that the high body lipid content of M. expansa provides an energy source supporting the high fecundity of this parasite. Our study provides insight into host interaction, adaptation, nutrient acquisition, strobilization, and reproduction in this parasite and this is also the first genome published in Anoplocephalidae.

Gill and liver transcriptomic responses of Achirus lineatus (Neopterygii: Achiridae) exposed to water-accommodated fraction (WAF) of light crude oil reveal an onset of hypoxia-like condition

Crude oil is one of the most widespread pollutants released into the marine environment, and native species have provided useful information about the effect of crude oil pollution in marine ecosystems. We consider that the lined sole Achirus lineatus can be a useful monitor of the effect of crude oil in the Gulf of Mexico (GoM) because this flounder species has a wide distribution along the GoM, and its response to oil components is relevant. The objective of this study was to compare the transcriptomic changes in liver and gill of adults lined sole fish (Achirus lineatus) exposed to a sublethal acute concentration of water-accommodated fraction (WAF) of light crude oil for 48 h. RNA-Seq was performed to assess the transcriptional changes in both organs. A total of 1073 differentially expressed genes (DEGs) were detected in gills; 662 (61.69%) were upregulated, and 411 (38.30%) were downregulated whereas in liver, 515 DEGs; 306 (59.42%) were upregulated, and 209 (40.58%) were downregulated. Xenobiotic metabolism and redox metabolism, along with DNA repair mechanisms, were activated. The induction of hypoxia-regulated genes and the generalized regulation of multiple signaling pathways support the hypothesis that WAF exposition causes a hypoxia-like condition.

Crystal structure of human brain-type fatty acid-binding protein FABP7 complexed with palmitic acid

The brain-type fatty acid-binding protein FABP7, which is expressed in astrocytes and neural progenitors, is a member of the intracellular lipid-binding protein family. This protein is not only involved in various cellular functions such as metabolism, inflammation and energy homeostasis, but also in diseases such as cognitive disorders and tumors. Structures of unsaturated fatty acids, such as oleic acid (OA) and docosahexaenoic acid (DHA), bound to FABP7 have been elucidated; however, structures of saturated fatty acids bound to FABP7 remain unknown. To better understand fatty acid recognition, here the crystal structure of human brain-type fatty acid-binding protein FABP7 complexed with palmitic acid (PA), a saturated fatty acid, is reported at a resolution of 1.6 Å. The PA bound to the fatty acid-binding pocket of FABP7 assumed a U-shaped conformation. The carboxylate moiety of PA interacted with Tyr129, Arg127 and, via a water bridge, with Arg107 and Thr54, whereas its aliphatic chain was stabilized by hydrophobic interactions with Met21, Leu24, Thr30, Thr37, Pro39, Phe58 and Asp77. Structural comparison showed that PA, OA and DHA exhibited unique binding conformations in the fatty acid-binding pocket, stabilized by distinct amino-acid interactions. The binding of PA to FABP7 exhibits a unique binding conformation when compared with other human FABPs (FABP3-FABP5 and FABP8) expressed in other tissues. Based on the crystal and fatty acid structures, it was suggested that PA, which prefers a linear form in nature, required a greater conformational change in its aliphatic chain to bind to the fatty acid-binding pocket in a U-shaped conformation, compared with the cis configurations of OA or DHA. This, together with the length of the aliphatic chain, was considered to be one of the factors determining the binding affinity of PA to FABP7. These results provide a better understanding of fatty acid recognition by FABP7 and expand the knowledge of the binding of PA to FABPs.