Fructose-1,6-bisphosphatase 1 Research Articles

Glycogenesis and glyconeogenesis from glutamine, lactate and glycerol support human macrophage functions.

Macrophages fight infection and ensure tissue repair, often operating at nutrient-poor wound sites. We investigated the ability of human macrophages to metabolize glycogen. We observed that the cytokines GM-CSF and M-CSF plus IL-4 induced glycogenesis and the accumulation of glycogen by monocyte-derived macrophages. Glyconeogenesis occurs in cells cultured in the presence of the inflammatory cytokines GM-CSF and IFNγ (M1 cells), via phosphoenolpyruvate carboxykinase 2 (PCK2) and fructose-1,6-bisphosphatase 1 (FBP1). Enzyme inhibition with drugs or gene silencing techniques and 13C-tracing demonstrate that glutamine (metabolized by the TCA cycle), lactic acid, and glycerol were substrates of glyconeogenesis only in M1 cells. Tumor-associated macrophages (TAMs) also store glycogen and can perform glyconeogenesis. Finally, macrophage glycogenolysis and the pentose phosphate pathway (PPP) support cytokine secretion and phagocytosis regardless of the availability of extracellular glucose. Thus, glycogen metabolism supports the functions of human M1 and M2 cells, with inflammatory M1 cells displaying a possible dependence on glyconeogenesis.

TRIM47 promotes the Warburg effect and reduces ferroptosis in prostate cancer by FBP1 and FOXO1.

Prostate cancer (PC), a malignant tumor occurring in the male prostate tissue, has a high incidence rate. In this study, we explored the role of tripartite motif 47 (TRIM47) in the progression of PC and its underlying mechanism. PC and paracancerous tissues were collected from Shenzhen Peoples's Hospital. The following methods were employed in this experiment: quantitative polymerase chain reaction (qPCR), immunofluorescent staining, cell counting kit-8 (CCK-8), ethynyl deoxyuridine (EdU), and Western blot. The expression levels of TRIM47 were up-regulated in patients with PC. TRIM47 was found to promote cell growth and induce the Warburg effect, while also reducing ferroptosis in PC cells. Conversely, the knockdown of TRIM47 [small interfering RNA, (si)-TRIM47] decreased cell growth and the Warburg effect, while promoting ferroptosis in PC cells. Additionally, TRIM47 was observed to induce the protein expression levels of fructose-1,6-bisphosphatase 1 (FBP1) and forkhead box protein O1 (FOXO1) in PC cells. Further, TRIM47 protein was found to interact with both the FBP1 and FOXO1 proteins in the PC cells. The inhibition of FBP1 attenuated the effects of TRIM47 on the Warburg effect in PC cells, while the inhibition of FOXO1 diminished the effects of TRIM47 on ferroptosis in PC cells. Our findings suggest that TRIM47 promotes the Warburg effect of PC by inducing FBP1 and FOXO1. Thus, our findings suggest that targeting TRIM47 could serve as a viable therapeutic strategy for the treatment of PC.

Inhibition of FBP1 expression by KMT5A through TWIST1 methylation is one of the mechanisms leading to chemoresistance in breast cancer.

Lysine methyltransferase 5A (KMT5A) is the sole mammalian enzyme known to catalyse the mono‑methylation of histone H4 lysine 20 and non‑histone proteins such as p53, which are involved in the occurrence and progression of numerous cancers. The present study aimed to determine the function of KMT5A in inducing docetaxel (DTX) resistance in patients with breast carcinoma by evaluating glucose metabolism and the underlying mechanism involved. The upregulation or downregulation of KMT5A‑related proteins was examined after KMT5A knockdown in breast cancer (BRCA) cells by Tandem Mass Tag proteomics. Through differential protein expression and pathway enrichment analysis, the upregulated key gluconeogenic enzyme fructose‑1,6‑bisphosphatase 1 (FBP1) was discovered. Loss of FBP1 expression is closely related to the development and prognosis of cancers. A dual‑luciferase reporter gene assay confirmed that KMT5A inhibited the expression of FBP1 and that overexpression of FBP1 could enhance the chemotherapeutic sensitivity to DTX through the suppression of KMT5A expression. The KMT5A inhibitor UNC0379 was used to verify that DTX resistance induced by KMT5A through the inhibition of FBP1 depended on the methylase activity of KMT5A. According to previous literature and interaction network structure, it was revealed that KMT5A acts on the transcription factor twist family BHLH transcription factor 1 (TWIST1). Then, it was verified that TWSIT1 promoted the expression of FBP1 by using a dual‑luciferase reporter gene experiment. KMT5A induces chemotherapy resistance in BRCA cells by promoting cell proliferation and glycolysis. After the knockdown of the KMT5A gene, the FBP1 related to glucose metabolism in BRCA was upregulated. KMT5A knockdown expression and FBP1 overexpression synergistically inhibit cell proliferation and block cells in the G2/M phase. KMT5A inhibits the expression of FBP1 by methylating TWIST1 and weakening its promotion of FBP1 transcription. In conclusion, KMT5A was shown to affect chemotherapy resistance by regulating the cell cycle and positively regulate glycolysis‑mediated chemotherapy resistance by inhibiting the transcription of FBP1 in collaboration with TWIST1. KMT5A may be a potential therapeutic target for chemotherapy resistance in BRCA.

FBP1 orchestrates keratinocyte proliferation/differentiation and suppresses psoriasis through metabolic control of histone acetylation

Keratinocyte proliferation and differentiation in epidermis are well-controlled and essential for reacting to stimuli such as ultraviolet light. Imbalance between proliferation and differentiation is a characteristic feature of major human skin diseases such as psoriasis and squamous cell carcinoma. However, the effect of keratinocyte metabolism on proliferation and differentiation remains largely elusive. We show here that the gluconeogenic enzyme fructose-1,6-bisphosphatase 1 (FBP1) promotes differentiation while inhibits proliferation of keratinocyte and suppresses psoriasis development. FBP1 is identified among the most upregulated genes induced by UVB using transcriptome sequencing and is elevated especially in upper epidermis. Fbp1 heterozygous mice exhibit aberrant epidermis phenotypes with local hyperplasia and dedifferentiation. Loss of FBP1 promotes proliferation and inhibits differentiation of keratinocytes in vitro. Mechanistically, FBP1 loss facilitates glycolysis-mediated acetyl-CoA production, which increases histone H3 acetylation at lysine 9, resulting in enhanced transcription of proliferation genes. We further find that the expression of FBP1 is dramatically reduced in human psoriatic lesions and in skin of mouse imiquimod psoriasis model. Fbp1 deficiency in mice facilitates psoriasis-like skin lesions development through glycolysis and acetyl-CoA production. Collectively, our findings reveal a previously unrecognized role of FBP1 in epidermal homeostasis and provide evidence for FBP1 as a metabolic psoriasis suppressor.

Documentation of a novel FBP1 gene mutation in the Arabian ethnicity: a case report

BackgroundFructose-1,6-bisphosphatase deficiency is a rare autosomal recessive disorder characterized by impaired gluconeogenesis. Fructose-1,6-bisphosphatase 1 (FBP1) mutations demonstrate ethnic patterns. For instance, Turkish populations commonly harbor exon 2 deletions. We present a case report of whole exon 2 deletion in a Syrian Arabian child as the first recording of this mutation among Arabian ethnicity and the first report of FBP1 gene mutation in Syria.Case presentationWe present the case of a 2.5-year-old Syrian Arab child with recurrent hypoglycemic episodes, accompanied by nausea and lethargy. The patient’s history, physical examination, and laboratory findings raised suspicion of fructose-1,6-bisphosphatase deficiency. Whole exome sequencing was performed, revealing a homozygous deletion of exon 2 in the FBP1 gene, confirming the diagnosis.ConclusionThis case highlights a potential novel mutation in the Arab population; this mutation is well described in the Turkish population, which suggests potential shared mutations due to ancestral relationships between the two ethnicities. Further studies are needed to confirm this finding.

Fructose-1,6-bisphosphatase 1 dephosphorylates and inhibits TERT for tumor suppression.

Telomere dysfunction is intricately linked to the aging process and stands out as a prominent cancer hallmark. Here we demonstrate that telomerase activity is differentially regulated in cancer and normal cells depending on the expression status of fructose-1,6-bisphosphatase 1 (FBP1). In FBP1-expressing cells, FBP1 directly interacts with and dephosphorylates telomerase reverse transcriptase (TERT) at Ser227. Dephosphorylated TERT fails to translocate into the nucleus, leading to the inhibition of telomerase activity, reduction in telomere lengths, enhanced senescence and suppressed tumor cell proliferation and growth in mice. Lipid nanoparticle-mediated delivery of FBP1 mRNA inhibits liver tumor growth. Additionally, FBP1 expression levels inversely correlate with TERT pSer227 levels in renal and hepatocellular carcinoma specimens and with poor prognosis of the patients. These findings demonstrate that FBP1 governs cell immortality through its protein phosphatase activity and uncover a unique telomerase regulation in tumor cells attributed to the downregulation or deficiency of FBP1 expression.

FBP1 inhibits NSCLC stemness by promoting ubiquitination of Notch1 intracellular domain and accelerating degradation

The existence of cancer stem cells is widely acknowledged as the underlying cause for the challenging curability and high relapse rates observed in various tumor types, including non-small cell lung cancer (NSCLC). Despite extensive research on numerous therapeutic targets for NSCLC treatment, the strategies to effectively combat NSCLC stemness and achieve a definitive cure are still not well defined. The primary objective of this study was to examine the underlying mechanism through which Fructose-1,6-bisphosphatase 1 (FBP1), a gluconeogenic enzyme, functions as a tumor suppressor to regulate the stemness of NSCLC. Herein, we showed that overexpression of FBP1 led to a decrease in the proportion of CD133-positive cells, weakened tumorigenicity, and decreased expression of stemness factors. FBP1 inhibited the activation of Notch signaling, while it had no impact on the transcription level of Notch 1 intracellular domain (NICD1). Instead, FBP1 interacted with NICD1 and the E3 ubiquitin ligase FBXW7 to facilitate the degradation of NICD1 through the ubiquitin–proteasome pathway, which is independent of the metabolic enzymatic activity of FBP1. The aforementioned studies suggest that targeting the FBP1-FBXW7-NICD1 axis holds promise as a therapeutic approach for addressing the challenges of NSCLC recurrence and drug resistance.

Associations between plasma metabolism associated proteins and future development of giant cell arteritis: results from a prospective study.

To investigate the relation between biomarkers associated with metabolism and subsequent development of giant cell arteritis (GCA). Participants in the population-based Malmö Diet Cancer Study (MDCS; N = 30447), who were subsequently diagnosed with GCA, were identified in a structured process. Matched GCA-free controls were selected from the study cohort. Baseline plasma samples were analyzed using the antibody-based OLINK proteomics metabolism panel (92 metabolic proteins). Analyses were pre-designated as hypothesis-driven or hypothesis-generating. In the latter, principal component analysis was used to identify groups of proteins that explain the variance in the proteome. There were 95 cases with a confirmed incident diagnosis of GCA (median 12.0 years after inclusion). Among biomarkers with a priori hypotheses, Adhesion G protein-coupled receptor E2 (ADGRE2) was positively associated (odds ratio (OR) per standard deviation (SD) 1.67; 95% CI 1.08-2.57), and Fructose-1,6-bisphosphatase 1 (FBP1) negatively associated (OR per SD 0.59; 95% CI 0.35-0.99) with GCA. In particular, ADGRE2 levels were associated with subsequent GCA in the subset sampled <8.5 years before diagnosis. For meteorin-like protein (Metrnl), the highest impact on the risk of GCA was observed in those sampled closest to diagnosis with a decreasing trend with longer time to GCA (p= 0.03). In the hypothesis generating analyses, elevated levels of receptor tyrosine-like orphan receptor 1 (ROR1) were associated with subsequent GCA. Biomarkers identified years before clinical diagnosis indicated a protective role of gluconeogenesis (FBP1) and an association with macrophage activation (ADGRE2 and Metrnl) and proinflammatory signals (ROR1) for development of GCA.

Activation of the pentose phosphate pathway in macrophages is crucial for granuloma formation in sarcoidosis.

Sarcoidosis is a disease of unknown etiology in which granulomas form throughout the body and is typically treated with glucocorticoids, but there are no approved steroid-sparing alternatives. Here, we investigated the mechanism of granuloma formation using single-cell RNA-Seq in sarcoidosis patients. We observed that the percentages of triggering receptor expressed on myeloid cells 2-positive (TREM2-positive) macrophages expressing angiotensin-converting enzyme (ACE) and lysozyme, diagnostic makers of sarcoidosis, were increased in cutaneous sarcoidosis granulomas. Macrophages in the sarcoidosis lesion were hypermetabolic, especially in the pentose phosphate pathway (PPP). Expression of the PPP enzymes, such as fructose-1,6-bisphosphatase 1 (FBP1), was elevated in both systemic granuloma lesions and serum of sarcoidosis patients. Granuloma formation was attenuated by the PPP inhibitors in in vitro giant cell and in vivo murine granuloma models. These results suggest that the PPP may be a promising target for developing therapeutics for sarcoidosis.

Piperlongumine based nanomedicine impairs glycolytic metabolism in triple negative breast cancer stem cells through modulation of GAPDH & FBP1

BackgroundTriple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer and exhibits high rate of chemoresistance, metastasis, and relapse. This can be attributed to the failure of conventional therapeutics to target a sub-population of slow cycling or quiescent cells called as cancer stem cells (CSCs). Therefore, elimination of CSCs is essential for effective TNBC treatment. PurposeResearch suggests that breast CSCs exhibit elevated glycolytic metabolism which directly contributes in maintenance of stemness, self-renewability and chemoresistance as well as in tumor progression. Therefore, this study aimed to target rewired metabolism which can serve as Achilles heel for CSCs population and have far reaching effect in TNBC treatment. MethodsWe used two preclinical models, zebrafish and nude mice to evaluate the fate of nanoparticles as well as the therapeutic efficacy of both piperlongumine (PL) and its nanomedicine (PL-NPs). ResultsIn this context, we explored a phytochemical piperlongumine (PL) which has potent anti-cancer properties but poor pharmacokinetics impedes its clinical translation. So, we developed PLGA based nanomedicine for PL (PL-NPs), and demonstrated that it overcomes the pharmacokinetic limitations of PL, along with imparting advantages of selective tumor targeting through Enhanced Permeability and Retention (EPR) effect in zebrafish xenograft model. Further, we demonstrated that PL-NPs efficiently inhibit glycolysis in CSCs through inhibition of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by modulating glutathione S-transferase pi 1 (GSTP1) and upregulation of fructose-1,6-bisphosphatase 1 (FBP1), a rate-limiting enzyme in gluconeogenesis. We also illustrated that inhibition of glycolysis results in overall tumor regression in two preclinical models. ConclusionThis study discusses novel mechanism of action by which PL acts on CSCSs. Taken together our study provides insight into development of PL based nanomedicine which could be exploited in clinics to achieve complete eradication of TNBC by targeting CSCs.

AF9 sustains glycolysis in colorectal cancer via H3K9ac-mediated PCK2 and FBP1 transcription.

The tumourigenesis of various cancers is influenced by epigenetic deregulation. Among 591 epigenetic regulator factors (ERFs) examined, AF9 showed significant inhibition of malignancy in colorectal cancer (CRC) based on our wound healing assays. However, the precise role of AF9 in CRC remains to be explored. To investigate the function of AF9 in CRC, we utilised small interfering RNAs (siRNAs) to knock down the expression of 591 ERFs. Subsequently, we performed wound healing assays to evaluate cell proliferation and migration. In vitro and in vivo assays were conducted to elucidate the potential impact of AF9 in CRC. Clinical samples were analysed to assess the association between AF9 expression and CRC prognosis. Additionally, an Azoxymethane-Dextran Sodium Sulfate (AOM/DSS) induced CRC AF9IEC-/- mouse model was employed to confirm the role of AF9 in CRC. To identify the target gene of AF9, RNA-seq and coimmunoprecipitation analyses were performed. Furthermore, bioinformatics prediction was applied to identify potential miRNAs that target AF9. Among the 591 ERFs examined, AF9 exhibited downregulation in CRC and showed a positive correlation with prolonged survival in CRC patients. In vitro and in vivo assays proved that depletion of AF9 could promote cell proliferation, migration as well as glycolysis. Specifically, knockout of MLLT3 (AF9) in intestinal epithelial cells significantly increased tumour formation induced by AOM/DSS. We also identified miR-145 could target 3'untranslated region of AF9 to suppress AF9 expression. Loss of AF9 led to decreased expression of gluconeogenic genes, including phosphoenolpyruvate carboxykinase 2 (PCK2) and fructose 1,6-bisphosphatase 1 (FBP1), subsequently promoting glucose consumption and tumourigenesis. AF9 is essential for the upregulation of PCK2 and FBP1, and the disruption of the miR-145/AF9 axis may serve as a potential target for the development of CRC therapeutics.

Immunodeficiency with susceptibility to lymphoma with complex genotype affecting energy metabolism (FBP1, ACAD9) and vesicle trafficking (RAB27A).

Inborn errors of immunity (IEI) are characterized by a dysfunction of the immune system leading to increased susceptibility to infections, impaired immune regulation and cancer. We present a unique consanguineous family with a history of Hodgkin lymphoma, impaired EBV control and a late onset hemophagocytic lymphohistiocytosis (HLH). Overall, family members presented with variable impairment of NK cell and cytotoxic T cell degranulation and cytotoxicity. Exome sequencing identified homozygous variants in RAB27A, FBP1 (Fructose-1,6-bisphosphatase 1) and ACAD9 (Acyl-CoA dehydrogenase family member 9). Variants in RAB27A lead to Griscelli syndrome type 2, hypopigmentation and HLH predisposition. Lymphoma is frequently seen in patients with hypomorphic mutations of genes predisposing to HLH. We hypothesize that the variants in FBP1 and ACAD9 might aggravate the clinical and immune phenotype, influence serial killing and lytic granule polarization by CD8 T cells. Understanding of the interplay between the multiple variants identified by whole exome sequencing (WES) is essential for correct interpretation of the immune phenotype and important for critical treatment decisions.

Oncogenic Role of the NFATC2/NEDD4/FBP1 Axis in Cholangiocarcinoma

Nuclear factor of activated T cells 2 (NFATC2) is reported to contribute to the initiation and progression of various cancers; however, its expression and function in cholangiocarcinoma (CCA) tissues remain elusive. Herein, we investigated the expression pattern, clinicopathologic characteristics, cell biological functions, and potential mechanisms of NFATC2 in CCA tissues. Real-time reverse-transcription PCR (RT-qPCR) and immunohistochemistry were performed to analyze the expression of NFATC2 in human CCA tissues. Cell counting kit 8, colony formation, flow cytometry, Western blotting, and Transwell assays, and in vivo xenograft and pulmonary metastasis models, were used to explore the effect of NFATC2 on the proliferation and metastasis of CCA. A dual-luciferase reporter system, oligonucleotide pull-down, chromatin immunoprecipitation, immunofluorescence, and coimmunoprecipitation were performed to reveal the potential mechanisms. We found that NFATC2 was upregulated in CCA tissues and cells, and its aberrantly high levels were associated with a poorer differentiation pattern. Functionally, NFATC2 overexpression promoted CCA cell proliferation and metastasis, whereas knockdown of NFATC2 led to opposite result. Mechanistically, NFATC2 could be enriched in the promoter region of neural precursor cell–expressed developmentally downregulated protein 4 (NEDD4) to facilitate its expression. Furthermore, NEDD4 targeted fructose-1, 6-bisphosphatase 1 (FBP1) and inhibited FBP1 expression via ubiquitination. In addition, silencing NEDD4 rescued the effects of NFATC2 overexpression on CCA cells. NEDD4 was upregulated in human CCA tissues, and its expression levels were positively correlated with those of NFATC2. We thus conclude that NFATC2 promotes the progression of CCA via the NEDD4/FBP1 axis, emphasizing the oncogenic role of NFATC2 in CCA progression.

A novel variant in the FBP1 gene causes fructose-1,6-bisphosphatase deficiency through increased ubiquitination

Fructose-1,6-bisphosphatase (FBPase) deficiency is an autosomal recessive disorder characterized by impaired gluconeogenesis caused by mutations in the fructose-1,6-bisphosphatase 1 (FBP1) gene. The molecular mechanisms underlying FBPase deficiency caused by FBP1 mutations require investigation. Herein, we report the case of a Chinese boy with FBPase deficiency who presented with hypoglycemia, ketonuria, metabolic acidosis, and repeated episodes of generalized seizures that progressed to epileptic encephalopathy. Whole-exome sequencing revealed compound heterozygous variants, c.761 A > G (H254R) and c.962C > T (S321F), in FBP1. The variants, especially the novel H254R, reduced protein stability and enzymatic activity in patient-derived leukocytes and transfected HepG2 and U251 cells. Mutant FBP1 undergoes enhanced ubiquitination and proteasomal degradation. NEDD4-2 was identified as an E3 ligase for FBP1 ubiquitination in transfected cells and the liver and brain of Nedd4-2 knockout mice. The H254R mutant FBP1 interacted with NEDD4-2 at significantly higher levels than the wild-type control. Our study identified a novel H254R variant of FBP1 underlying FBPase deficiency and elucidated the molecular mechanism underlying the enhanced NEDD4-2-mediated ubiquitination and proteasomal degradation of mutant FBP1.

Novel function for gluconeogenic enzyme, FBP1, in T cell activation and expansion

Abstract During an immune response, naïve T lymphocytes undergo rapid clonal expansion and must reprogram their metabolism to meet high energetic and biosynthetic demands. The sudden increase in metabolic activity associated with a proliferative burst generates reactive oxygen species (ROS) increasing intracellular oxidative stress, which can disrupt homeostasis or trigger cell death, unless properly regulated. Our studies show that a constitutively active isoform of gluconeogenic enzyme, fructose 1,6-bisphosphatase 1 (FBP1), facilitates re-entry of glucose carbons into the pentose phosphate pathway to ensure the sustained production of NADPH for redox homeostasis and lipid synthesis in stimulated T cells as they transition to a phase of rapid growth, and is essential for their unperturbed clonal expansion and for an effective immune response. Wildtype (wt) FBP1, which catalyzes hydrolysis of fructose-1,6 bisphosphate in an irreversible reaction, has a C-terminal catalytic domain and an inhibitory N-terminal regulatory domain. We demonstrate that a short isoform of FBP1 representing the catalytic domain is induced in human T cells within 24 hours of co-stimulation. The short isoform, FBP1-CD, is the product of an alternatively spliced transcript and is resistant to inhibitors that suppress activity of wt FBP1, which harbors the regulatory domain. FBP1-CD levels and enzyme activity are significantly reduced 5 days post-stimulation, correlating positively with proliferation and inversely with ROS and apoptosis in T cells. In addition to new insights into immune regulation, our studies reveal a broader role for FBP1 in regulating proliferative metabolism and offer a rational explanation for the suppression of FBP1 in solid tumors. Supported by grant from NIH (R21 AI168777)

RNA-Sequencing Characterization of lncRNA and mRNA Functions in Septic Pig Liver Injury.

We assessed differentially expressed (DE) mRNAs and lncRNAs in the liver of septic pigs to explore the key factors regulating lipopolysaccharide (LPS)-induced liver injury. We identified 543 DE lncRNAs and 3642 DE mRNAs responsive to LPS. Functional enrichment analysis revealed the DE mRNAs were involved in liver metabolism and other pathways related to inflammation and apoptosis. We also found significantly upregulated endoplasmic reticulum stress (ERS)-associated genes, including the receptor protein kinase receptor-like endoplasmic reticulum kinase (PERK), the eukaryotic translation initiation factor 2α (EIF2S1), the transcription factor C/EBP homologous protein (CHOP), and activating transcription factor 4 (ATF4). In addition, we predicted 247 differentially expressed target genes (DETG) of DE lncRNAs. The analysis of protein-protein interactions (PPI) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway detected key DETGs that are involved in metabolic pathways, such as N-Acetylgalactosaminyltransferase 2 (GALNT2), argininosuccinate synthetase 1 (ASS1), and fructose 1,6-bisphosphatase 1 (FBP1). LNC_003307 was the most abundant DE lncRNA in the pig liver, with a marked upregulation of >10-fold after LPS stimulation. We identified three transcripts for this gene using the rapid amplification of the cDNA ends (RACE) technique and obtained the shortest transcript sequence. This gene likely derives from the nicotinamide N-methyltransferase (NNMT) gene in pigs. According to the identified DETGs of LNC_003307, we hypothesize that this gene regulates inflammation and endoplasmic reticulum stress in LPS-induced liver damage in pigs. This study provides a transcriptomic reference for further understanding of the regulatory mechanisms underlying septic hepatic injury.

Hepatic but not Intestinal FBP1 Is Required for Fructose Metabolism and Tolerance.

Fructose intolerance in mammals is caused by defects in fructose absorption and metabolism. Fructose-1,6-bisphosphatase 1 (FBP1) is a key enzyme in gluconeogenesis, and its deficiency results in hypoglycemia as well as intolerance to fructose. However, the mechanism about fructose intolerance caused by FBP1 deficiency has not been fully elucidated. Here, we demonstrate that hepatic but not intestinal FBP1 is required for fructose metabolism and tolerance. We generated inducible knockout mouse models specifically lacking FBP1 in adult intestine or liver. Intestine-specific deletion of Fbp1 in adult mice does not compromise fructose tolerance, as evidenced by no significant body weight loss, food intake reduction, or morphological changes of the small intestine during 4 weeks of exposure to a high-fructose diet. By contrast, liver-specific deletion of Fbp1 in adult mice leads to fructose intolerance, as manifested by substantial weight loss, hepatomegaly, and liver injury after exposure to a high-fructose diet. Notably, the fructose metabolite fructose-1-phosphate is accumulated in FBP1-deficient liver after fructose challenge, which indicates a defect of fructolysis, probably due to competitive inhibition by fructose-1,6-bisphosphate and may account for the fructose intolerance. In conclusion, these data have clarified the essential role of hepatic but not intestinal FBP1 in fructose metabolism and tolerance.

Tandem mass tag-based quantitative proteomic profiling identifies candidate serum biomarkers of drug-induced liver injury in humans

Diagnosis of drug-induced liver injury (DILI) and its distinction from other liver diseases are significant challenges in drug development and clinical practice. Here, we identify, confirm, and replicate the biomarker performance characteristics of candidate proteins in patients with DILI at onset (DO; n = 133) and follow-up (n = 120), acute non-DILI at onset (NDO; n = 63) and follow-up (n = 42), and healthy volunteers (HV; n = 104). Area under the receiver operating characteristic curve (AUC) for cytoplasmic aconitate hydratase, argininosuccinate synthase, carbamoylphosphate synthase, fumarylacetoacetase, fructose-1,6-bisphosphatase 1 (FBP1) across cohorts achieved near complete separation (range: 0.94–0.99) of DO and HV. In addition, we show that FBP1, alone or in combination with glutathione S-transferase A1 and leukocyte cell-derived chemotaxin 2, could potentially assist in clinical diagnosis by distinguishing NDO from DO (AUC range: 0.65–0.78), but further technical and clinical validation of these candidate biomarkers is needed.

Evaluation of Tazemetostat as a Therapeutically Relevant Substance in Biliary Tract Cancer.

Biliary tract cancer (BTC) is a gastrointestinal malignancy associated with a poor survival rate. Current therapies encompass palliative and chemotherapeutic treatment as well as radiation therapy, which results in a median survival of only one year due to standard therapeutic ineffectiveness or resistance. Tazemetostat is an FDA-approved inhibitor of enhancer of Zeste homolog 2 (EZH2), a methyltransferase involved in BTC tumorigenesis via trimethylation of histone 3 at lysine 27 (H3K27me3), an epigenetic mark associated with silencing of tumor suppressor genes. Up to now, there are no data available regarding tazemetostat as a possible treatment option against BTC. Therefore, the aim of our study is a first-time investigation of tazemetostat as a potential anti-BTC substance in vitro. In this study, we demonstrate that tazemetostat affects cell viability and the clonogenic growth of BTC cells in a cell line-dependent manner. Furthermore, we found a strong epigenetic effect at low concentrations of tazemetostat, which was independent of the cytotoxic effect. We also observed in one BTC cell line that tazemetostat increases the mRNA levels and protein expression of the tumor suppressor gene Fructose-1,6-bisphosphatase 1 (FBP1). Interestingly, the observed cytotoxic and epigenetic effects were independent of the mutation status of EZH2. To conclude, our study shows that tazemetostat is a potential anti-tumorigenic substance in BTC with a strong epigenetic effect.

Down-regulation of FBP1 in lung adenocarcinoma cells promotes proliferation and invasion through SLUG mediated epithelial mesenchymal transformation.

Metabolic reprogramming and epithelial-mesenchymal transformation (EMT) play an important role in lung cancer. In recent studies, metabolic enzymes such as Fructose-1,6-bisphosphatase 1 (FBP1) have shown potential functions beyond regulating metabolism. Western blot assay was performed to detect glycolysis-related and EMT-related protein expression levels. The glucose uptake kit and adenosine triphosphate (ATP) detection kit were used to detect glucose uptake rate and ATP content. Transwell assay was used to determine the invasiveness of lung adenocarcinoma cells. Wound healing assay was used to determine the metastatic ability of lung adenocarcinoma cells. Methyl thiazolyl tetrazolium (MTT) assay and EdU staining were performed to investigate the effect of FBP1 overexpression on lung adenocarcinoma proliferation. Overexpression of FBP1 down-regulated glycolysis-related protein levels and inhibited glucose uptake and ATP production, while knockdown of FBP1 had the opposite effect. Overexpression of FBP1 reversed EMT and inhibited Slug expression. Meanwhile, overexpression of FBP1 impaired the invasion, metastasis and proliferation ability of lung adenocarcinoma cells. In contrast, FBP1 knockdown promoted the EMT process, up-regulated Slug expression and enhanced the invasion, metastasis and proliferation of lung adenocarcinoma cells. Therefore, FBP1 can be used as one of the potential clinical targets through inhibiting glycolysis, cell invasion and proliferation by inhibiting Slug mediated EMT processes.