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 mono­methylation of histone H4 lysine 20 and non­histone 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 KMT5A­related 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 fructose­1,6­bisphosphatase 1 (FBP1) was discovered. Loss of FBP1 expression is closely related to the development and prognosis of cancers. A dual­luciferase 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 dual­luciferase 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 glycolysis­mediated chemotherapy resistance by inhibiting the transcription of FBP1 in collaboration with TWIST1. KMT5A may be a potential therapeutic target for chemotherapy resistance in BRCA.

Metabolomics Reveals the Impact of Overexpression of Cytosolic Fructose-1,6-Bisphosphatase on Photosynthesis and Growth in Nannochloropsis gaditana.

Nannochloropsis gaditana, a microalga known for its photosynthetic efficiency, serves as a cell factory, producing valuable biomolecules such as proteins, lipids, and pigments. These components make it an ideal candidate for biofuel production and pharmaceutical applications. In this study, we genetically engineered N. gaditana to overexpress the enzyme fructose-1,6-bisphosphatase (cyFBPase) using the Hsp promoter, aiming to enhance sugar metabolism and biomass accumulation. The modified algal strain, termed NgFBP, exhibited a 1.34-fold increase in cyFBPase activity under photoautotrophic conditions. This modification led to a doubling of biomass production and an increase in eicosapentaenoic acid (EPA) content in fatty acids to 20.78-23.08%. Additionally, the genetic alteration activated the pathways related to glycine, protoporphyrin, thioglucosides, pantothenic acid, CoA, and glycerophospholipids. This shift in carbon allocation towards chloroplast development significantly enhanced photosynthesis and growth. The outcomes of this study not only improve our understanding of photosynthesis and carbon allocation in N. gaditana but also suggest new biotechnological methods to optimize biomass yield and compound production in microalgae.

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.

MiR827 positively regulates the resistance to chilli veinal mottle virus by affecting the expression of FBPase in Nicotiana benthamiana.

MicroRNA(miRNA) is a class of non-coding small RNA that plays an important role in plant growth, development, and response to environmental stresses. Unlike most miRNAs, which usually target homologous genes across a variety of species, miR827 targets different types of genes in different species. Research on miR827 mainly focuses on its role in regulating phosphate (Pi) homeostasis of plants, however, little is known about its function in plant response to virus infection. In the present study, miR827 was significantly upregulated in the recovery tissue of virus-infected Nicotiana tabacum. Overexpression of miR827 could improve plants resistance to the infection of chilli veinal mottle virus (ChiVMV) in Nicotiana benthamiana, whereas interference of miR827 increased the susceptibility of the virus-infected plants. Further experiments indicated that the antiviral defence regulated by miR827 was associated with the reactive oxygen species and salicylic acid signalling pathways. Then, fructose-1,6-bisphosphatase (FBPase) was identified to be a target of miR827, and virus infection could affect the expression of FBPase. Finally, transient expression of FBPase increased the susceptibility to ChiVMV-GFP infection in N. benthamiana. By contrast, silencing of FBPase increased plant resistance. Taken together, our results demonstrate that miR827 plays a positive role in tobacco response to virus infection, thus providing new insights into understanding the role of miR827 in plant-virus interaction.

Expression Regulation of Gluconeogenesis Related Genes in Ovine Skeletal Muscle Cells.

BACKGROUND: Under fasting conditions, the pathway converting gluconeogenesis precursors into muscle glycogen becomes crucial due to reduced glycogen reserves. However, there is limited research on skeletal muscle gluconeogenesis and the impact of fasting on gluconeogenic gene expression. METHODS: Sheep fetal skeletal muscle cells cultured in vitro were used to study the effects of varying lactic acid concentrations (0 to 30 mM) and 2.5 mM glucose on the expression of gluconeogenesis-related genes after 6 h of fasting. The effects on mRNA and protein expression of key genes involved in skeletal muscle gluconeogenesis were measured by quantitative real time polymerase chain reaction (qRT-PCR), immunofluorescence, and western blotting at 48 h. RESULTS: Fasting increased the expression of key gluconeogenic genes, fructose-1,6-bisphosphatase 2 (FBP2), glucose-6-phosphatase 3 (G6PC3), pyruvate kinase M (PKM), monocarboxylate transporter1 (MCTS1), glucose transporter type 4 (GLUT4), pyruvate carboxylase (PC), and lactate dehydrogenase A (LDHA). The mRNA levels of FBP2, G6PC3, and MCTS1 significantly decreased with glucose addition. Additionally, 10 mM lactic acid significantly promoted the expression of FBP2, PC, MCTS1, LDHA, GLUT4, and PKM while inhibiting phosphoenolpyruvate carboxykinase (PEPCK) expression. At the protein level, 10 mM lactic acid significantly increased FBP2 and PKM protein expression. CONCLUSIONS: This study shows that fasting regulates key gluconeogenic gene expression in sheep skeletal muscle cells and highlights the role of lactic acid in inducing these gene expressions.

[DNA assembly by multi-fragment digestion/ligation and homologous recombination].

To develop an accurate and efficient protocol for multi-fragment assembly and multi-site mutagenesis, we integrated and optimized the common multi-fragment assembly methods and validated the established method by using fructose-1,6-diphosphatase 1 (FBP1) with 4 mutant sites. The fragments containing mutations were assembled by introducing mutant sites and Bsa I recognition sequences. After digestion/ligation, the ligated fragment was amplified with the primers containing overlap region to the linearized vector. The amplified fragment was ligated to the linearized vector and the ligation product was transformed into Escherichia coli. After screening and sequencing, the recombinant plasmid with 4 mutant sites was obtained. This protocol overcame the major defects of Gibson assembly and Golden Gate assembly, serving as an efficient solution for multi-fragment assembly and multi-site mutagenesis.

Understanding the role of the fructose-1,6-bisphosphatase gene for enhancing the photosynthetic rate in Arabidopsis thaliana.

Transgenic Arabidopsis thaliana (ecotype Columbia) was successfully transformed with the gene fructose-1,6-bisphosphatase (FBPas e) and named as AtFBPase plants. Transgenic plants exhibited stable transformation, integration and significantly higher expressions for the transformed gene. Morphological evaluation of transgenic plants showed increased plant height (35cm), number of leaves (25), chlorophyll contents (28%), water use efficiency (increased from 1.5 to 2.6µmol CO2 µmol-1 H2 O) and stomatal conductance (20%), which all resulted in an enhanced photosynthetic rate (2.7µmolm-2 s-1 ) compared to wild type plants. This study suggests the vital role of FBPase gene in the modification of regulatory pathways to enhance the photosynthetic rate, which can also be utilised for economic crops in future.

Divergent Protein Redox Dynamics and Their Relationship with Electron Transport Efficiency during Photosynthesis Induction.

Various chloroplast proteins are activated/deactivated during the light/dark cycle via the redox regulation system. Although the photosynthetic electron transport chain provides reducing power to redox-sensitive proteins via the ferredoxin (Fd)/thioredoxin (Trx) pathway for their enzymatic activity control, how the redox states of individual proteins are linked to electron transport efficiency remains uncharacterized. Here we addressed this subject with a focus on the photosynthetic induction phase. We used Arabidopsis plants, in which the amount of Fd-Trx reductase (FTR), a core component in the Fd/Trx pathway, was genetically altered. Several chloroplast proteins showed different redox shift responses toward low- and high-light treatments. The light-dependent reduction of Calvin-Benson cycle enzymes fructose 1,6-bisphosphatase (FBPase) and sedoheptulose 1,7-bisphosphatase (SBPase) was partially impaired in the FTR-knockdown ftrb mutant. Simultaneous analyses of chlorophyll fluorescence and P700 absorbance change indicated that the induction of the electron transport reactions was delayed in the ftrb mutant. FTR overexpression also mildly affected the reduction patterns of FBPase and SBPase under high-light conditions, which were accompanied by the modification of electron transport properties. Accordingly, the redox states of FBPase and SBPase were linearly correlated with electron transport rates. In contrast, ATP synthase was highly reduced even when electron transport reactions were not fully induced. Furthermore, the redox response of proton gradient regulation 5-like photosynthetic phenotype1 (PGRL1; a protein involved in cyclic electron transport) did not correlate with electron transport rates. Our results provide insights into the working dynamics of the redox regulation system and their differential associations with photosynthetic electron transport efficiency.

Novel compound heterozygous mutations of the FBP1 gene in a patient with hypoglycemia and lactic acidosis: A case report.

BACKGROUND: Fructose-1,6-bisphosphatase (FBPase) deficiency, caused by an FBP1 mutation, is an autosomal recessively inherited metabolic disorder characterized by impaired gluconeogenesis. Due to the rarity of FBPase deficiency, the mechanism by which the mutations cause enzyme activity loss still remains unclear. METHODS: We report a pediatric patient with typical FBPase deficiency who presented with hypoglycemia, hyperlactatemia, metabolic acidosis, and hyperuricemia. Whole-exome sequencing was used to search for pathogenic genes, Sanger sequencing was used for verification, and molecular dynamic simulation was used to evaluate how the novel mutation affects FBPase activity and structural stability. RESULTS: Direct and allele-specific sequence analysis of the FBP1 gene (NM_000507) revealed that the proband had a compound heterozygote for the c. 490 (exon 4) G>A (p. G164S) and c. 861 (exon 7) C>A (p. Y287X, 52), which he inherited from his carrier parents. His father and mother had heterozygous G164S and Y287X mutations, respectively, without any symptoms of hypoglycemia. CONCLUSION: Our results broaden the known mutational spectrum and possible clinical phenotype of FBP1.

Fructose-bisphosphatase1 (FBP1) alleviates experimental osteoarthritis by regulating Protein crumbs homolog 3 (CRB3).

PURPOSE: To identify the role of gluconeogenesis in chondrocytes in osteoarthritis (OA). MATERIALS AND METHODS: Cartilage samples were collected from OA patients and C57 mice and were stained with Safranin O-Fast Green to determine the severity of OA. Periodic acid Schiff staining was used to characterize the contents of polysaccharides and SA-ßGal staining was used to characterize the aging of chondrocytes. Immunohistochemistry and western blotting were used to detect fructose-bisphosphatase1 (FBP1), SOX9, MMP13, P21, and P16 in cartilage or chondrocyte. The mRNA levels of fbp1, mmp13, sox9, colX, and acan were analyzed by qPCR to evaluate the role of FBP1 in chondrocytes. RESULTS: The level of polysaccharides in cartilage was reduced in OA and the expression of FBP1 was also reduced. We treated the chondrocytes with IL-1ß to cause OA in vitro, and then made chondrocytes overexpress FBP1 with plasma. It shows that FBP1 alleviated the degeneration and senescence of chondrocytes in vitro and that it also showed the same effects in vivo experiments. To further understand the mechanism of FBP1, we screened the downstream protein of FBP1 and found that CRB3 was significantly downregulated. And we confirmed that CRB3 suppressed the degeneration and delayed senescence of chondrocytes. CONCLUSIONS: FBP1 promoted the polysaccharide synthesis in cartilage and alleviated the degeneration of cartilage by regulating CRB3, so FBP1 is a potential target in treating OA.

Glycolytic enzyme PFKFB3 regulates sphingosine 1-phosphate receptor 1 in proangiogenic glomerular endothelial cells under diabetic condition.

Glomerular angiogenesis is a characteristic feature of diabetic nephropathy (DN). Enhanced glycolysis plays a crucial role in angiogenesis. The present study was designed to investigate the role of glycolysis in glomerular endothelial cells (GECs) in a mouse model of DN. Mouse renal cortex and isolated glomerular cells were collected for single-cell and RNA sequencing. Cultured GECs were exposed to high glucose in the presence (proangiogenic) and absence of a vascular sprouting regimen. MicroRNA-590-3p was delivered by lipofectamine in vivo and in vitro. In the present study, a subgroup of GECs with proangiogenic features was identified in diabetic kidneys by using sequencing analyses. In cultured proangiogenic GECs, high glucose increased glycolysis and phosphofructokinase/fructose bisphosphatase 3 (PFKFB3) protein expression, which were inhibited by overexpressing miRNA-590-3p. Mimics of miRNA-590-3p also increased receptor for sphingosine 1-phosphate (S1pR1) expression, an angiogenesis regulator, in proangiogenic GECs challenged with high glucose. Inhibition of PFKFB3 by pharmacological and genetic approaches upregulated S1pR1 protein in vitro. Mimics of miRNA-590-3p significantly reduced migration and angiogenic potential in proangiogenic GECs challenged with high glucose. Ten-week-old type 2 diabetic mice had elevated urinary albumin levels, reduced renal cortex miRNA-590-3p expression, and disarrangement of glomerular endothelial cell fenestration. Overexpressing miRNA-590-3p via perirenal adipose tissue injection restored endothelial cell fenestration and reduced urinary albumin levels in diabetic mice. Therefore, the present study identifies a subgroup of GECs with proangiogenic features in mice with DN. Local administration of miRNA-590-3p mimics reduces glycolytic rate and upregulates S1pR1 protein expression in proangiogenic GECs. The protective effects of miRNA-590-3p provide therapeutic potential in DN treatment.NEW & NOTEWORTHY Proangiogenetic glomerular endothelial cells (GECs) are activated in diabetic nephropathy. High glucose upregulates glycolytic enzyme phosphofructokinase/fructose bisphosphatase 3 (PFKFB3) in proangiogenetic cells. PFKFB3 protects the glomerular filtration barrier by targeting endothelial S1pR1. MiRNA-590-3p restores endothelial cell function and mitigates diabetic nephropathy.

Identification of genotype-biochemical phenotype correlations associated with fructose 1,6-bisphosphatase deficiency.

Fructose-1,6-bisphosphatase (FBPase) deficiency, caused by an FBP1 mutation, is an autosomal recessive disorder characterized by hypoglycemic lactic acidosis. Due to the rarity of FBPase deficiency, the mechanism by which the mutations cause enzyme activity loss still remains unclear. Here we identify compound heterozygous missense mutations of FBP1, c.491G>A (p.G164D) and c.581T>C (p.F194S), in an adult patient with hypoglycemic lactic acidosis. The G164D and F194S FBP1 mutants exhibit decreased FBP1 protein expression and a loss of FBPase enzyme activity. The biochemical phenotypes of all previously reported FBP1 missense mutations in addition to G164D and F194S are classified into three functional categories. Type 1 mutations are located at pivotal residues in enzyme activity motifs and have no effects on protein expression. Type 2 mutations structurally cluster around the substrate binding pocket and are associated with decreased protein expression due to protein misfolding. Type 3 mutations are likely nonpathogenic. These findings demonstrate a key role of protein misfolding in mediating the pathogenesis of FBPase deficiency, particularly for Type 2 mutations. This study provides important insights that certain patients with Type 2 mutations may respond to chaperone molecules.

New structures of Class II Fructose-1,6-Bisphosphatase from Francisella tularensis provide a framework for a novel catalytic mechanism for the entire class.

Class II Fructose-1,6-bisphosphatases (FBPaseII) (EC: 3.1.3.11) are highly conserved essential enzymes in the gluconeogenic pathway of microorganisms. Previous crystallographic studies of FBPasesII provided insights into various inactivated states of the enzyme in different species. Presented here is the first crystal structure of FBPaseII in an active state, solved for the enzyme from Francisella tularensis (FtFBPaseII), containing native metal cofactor Mn2+ and complexed with catalytic product fructose-6-phosphate (F6P). Another crystal structure of the same enzyme complex is presented in the inactivated state due to the structural changes introduced by crystal packing. Analysis of the interatomic distances among the substrate, product, and divalent metal cations in the catalytic centers of the enzyme led to a revision of the catalytic mechanism suggested previously for class II FBPases. We propose that phosphate-1 is cleaved from the substrate fructose-1,6-bisphosphate (F1,6BP) by T89 in a proximal α-helix backbone (G88-T89-T90-I91-T92-S93-K94) in which the substrate transition state is stabilized by the positive dipole of the 〈-helix backbone. Once cleaved a water molecule found in the active site liberates the inorganic phosphate from T89 completing the catalytic mechanism. Additionally, a crystal structure of Mycobacterium tuberculosis FBPaseII (MtFBPaseII) containing a bound F1,6BP is presented to further support the substrate binding and novel catalytic mechanism suggested for this class of enzymes.

Fructose-1,6-bisphosphatase 1 dephosphorylates IκBα and suppresses colorectal tumorigenesis.

Emerging evidence demonstrates that some metabolic enzymes that phosphorylate soluble metabolites can also phosphorylate a variety of protein substrates as protein kinases to regulate cell cycle, apoptosis and many other fundamental cellular processes. However, whether a metabolic enzyme dephosphorylates protein as a protein phosphatase remains unknown. Here we reveal the gluconeogenic enzyme fructose 1,6-biphosphatase 1 (FBP1) that catalyzes the hydrolysis of fructose 1,6-bisphosphate (F-1,6-BP) to fructose 6-phosphate (F-6-P) as a protein phosphatase by performing a high-throughput screening of metabolic phosphatases with molecular docking followed by molecular dynamics (MD) simulations. Moreover, we identify IκBα as the substrate of FBP1-mediated dephosphorylation by performing phosphoproteomic analysis. Mechanistically, FBP1 directly interacts with and dephosphorylates the serine (S) 32/36 of IκBα upon TNFα stimulation, thereby inhibiting NF-κB activation. MD simulations indicate that the catalytic mechanism of FBP1-mediated IκBα dephosphorylation is similar to F-1,6-BP dephosphorylation, except for higher energetic barriers for IκBα dephosphorylation. Functionally, FBP1-dependent NF-κB inactivation suppresses colorectal tumorigenesis by sensitizing tumor cells to inflammatory stresses and preventing the mobilization of myeloid-derived suppressor cells. Our finding reveals a previously unrecognized role of FBP1 as a protein phosphatase and establishes the critical role of FBP1-mediated IκBα dephosphorylation in colorectal tumorigenesis.

Expression of fructose-1,6-bisphosphatase 1 is associated with [18F]FDG uptake and prognosis in patients with mesial temporal lobe epilepsy.

OBJECTIVES: To determine whether fructose-1,6-bisphosphatase 1 (FBP1) expression is associated with [18F]FDG PET uptake and postsurgical outcomes in patients with mesial temporal lobe epilepsy (mTLE) and to investigate whether the molecular mechanism involving gamma-aminobutyric acid type A receptor (GABAAR), glucose transporter-3 (GLUT-3), and hexokinase-II (HK-II). METHODS: Forty-three patients with mTLE underwent [18F]FDG PET/CT. Patients were divided into Ia (Engel class Ia) and non-Ia (Engel class Ib-IV) groups according to more than 1 year of follow-up after surgery. The maximum standard uptake value (SUVmax) and asymmetry index (AI) of hippocampus were measured. The relationship among the SUVmax, AI, prognosis, and FBP1 expression was analyzed. A lithium-pilocarpine acute mTLE rat model was subjected to [18F]FDG micro-PET/CT. Hippocampal SUVmax and FBP1, GABAAR, GLUT-3, and HK-II expression were analyzed. RESULTS: SUVmax was higher in the Ia group than in the non-Ia group (7.31 ± 0.97 vs. 6.56 ± 0.96, p < 0.05) and FBP1 expression was lower in the Ia group (0.24 ± 0.03 vs. 0.27 ± 0.03, p < 0.01). FBP1 expression was negatively associated with SUVmax and AI (p < 0.01). In mTLE rats, the hippocampal FBP1 increased (0.26 ± 0.00 vs. 0.17 ± 0.00, p < 0.0001), and SUVmax, GLUT-3 and GABAAR levels decreased significantly (0.73 ± 0.12 vs. 1.46 ± 0.23, 0.20 ± 0.01 vs. 0.32 ± 0.05, 0.26 ± 0.02 vs. 0.35 ± 0.02, p < 0.05); no significant difference in HK-II levels was observed. In mTLE patients and rats, FBP1 negatively correlated with SUVmax and GLUT-3 and GABAAR levels (p < 0.05). CONCLUSION: FBP1 expression was inversely associated with SUVmax in mTLE, which might inhibit [18F]FDG uptake by regulating GLUT-3 expression. High FBP1 expression was indicative of low GABAAR expression and poor prognosis. KEY POINTS: • It is of paramount importance to explore the deep pathophysiological mechanisms underlying the pathogenesis of mesial temporal lobe epilepsy and find potential therapeutic targets. • [18F]FDG PET has demonstrated low metabolism in epileptic regions during the interictal period, and hypometabolism may be associated with prognosis, but the pathomechanism of this association remains uncertain. • Our results support the possibility that FBP1 might be simultaneously involved in the regulation of glucose metabolism levels and the excitability of neurons and suggest that targeting FBP1 may be a viable strategy in the diagnosis and treatment of mesial temporal lobe epilepsy.

Multi-Layered Regulations on the Chromatin Architectures: Establishing the Tight and Specific Responses of Fission Yeast fbp1 Gene Transcription.

Transcriptional regulation is pivotal for all living organisms and is required for adequate response to environmental fluctuations and intercellular signaling molecules. For precise regulation of transcription, cells have evolved regulatory systems on the genome architecture, including the chromosome higher-order structure (e.g., chromatin loops), location of transcription factor (TF)-binding sequences, non-coding RNA (ncRNA) transcription, chromatin configuration (e.g., nucleosome positioning and histone modifications), and the topological state of the DNA double helix. To understand how these genome-chromatin architectures and their regulators establish tight and specific responses at the transcription stage, the fission yeast fbp1 gene has been analyzed as a model system for decades. The fission yeast fbp1 gene is tightly repressed in the presence of glucose, and this gene is induced by over three orders of magnitude upon glucose starvation with a cascade of multi-layered regulations on various levels of genome and chromatin architecture. In this review article, we summarize the multi-layered transcriptional regulatory systems revealed by the analysis of the fission yeast fbp1 gene as a model system.

FBP1-Altered Carbohydrate Metabolism Reduces Leukemic Viability through Activating P53 and Modulating the Mitochondrial Quality Control System In Vitro.

Acute myeloid leukemia (AML)-the most frequent form of adult blood cancer-is characterized by heterogeneous mechanisms and disease progression. Developing an effective therapeutic strategy that targets metabolic homeostasis and energy production in immature leukemic cells (blasts) is essential for overcoming relapse and improving the prognosis of AML patients with different subtypes. With respect to metabolic regulation, fructose-1,6-bisphosphatase 1 (FBP1) is a gluconeogenic enzyme that is vital to carbohydrate metabolism, since gluconeogenesis is the central pathway for the production of important metabolites and energy necessary to maintain normal cellular activities. Beyond its catalytic activity, FBP1 inhibits aerobic glycolysis-known as the "Warburg effect"-in cancer cells. Importantly, while downregulation of FBP1 is associated with carcinogenesis in major human organs, restoration of FBP1 in cancer cells promotes apoptosis and prevents disease progression in solid tumors. Recently, our large-scale sequencing analyses revealed FBP1 as a novel inducible therapeutic target among 17,757 vitamin-D-responsive genes in MV4-11 or MOLM-14 blasts in vitro, both of which were derived from AML patients with FLT3 mutations. To investigate FBP1's anti-leukemic function in this study, we generated a new AML cell line through lentiviral overexpression of an FBP1 transgene in vitro (named FBP1-MV4-11). Results showed that FBP1-MV4-11 blasts are more prone to apoptosis than MV4-11 blasts. Mechanistically, FBP1-MV4-11 blasts have significantly increased gene and protein expression of P53, as confirmed by the P53 promoter assay in vitro. However, enhanced cell death and reduced proliferation of FBP1-MV4-11 blasts could be reversed by supplementation with post-glycolytic metabolites in vitro. Additionally, FBP1-MV4-11 blasts were found to have impaired mitochondrial homeostasis through reduced cytochrome c oxidase subunit 2 (COX2 or MT-CO2) and upregulated PTEN-induced kinase (PINK1) expressions. In summary, this is the first in vitro evidence that FBP1-altered carbohydrate metabolism and FBP1-activated P53 can initiate leukemic death by activating mitochondrial reprogramming in AML blasts, supporting the clinical potential of FBP1-based therapies for AML-like cancers.

The role of LINC01419 in regulating the cell stemness in lung adenocarcinoma through recruiting EZH2 and regulating FBP1 expression.

BACKGROUND: Recent years have witnessed a growing academic interest in the effects of lncRNAs on tumors. LINC01419 is found to facilitate proliferation and metastasis of lung adenocarcinoma (LUAD) cells, but there is a great deal of uncertainty about how LINC01419 works on LUAD cell stemness. For this reason, the focus of this research is centered on the regulatory impact of LINC01419 on LUAD cell stemness. METHODS: For the detection of the expression level of LINC01419 in LUAD, qRT-PCR was performed. And how oe-LINC01419 and sh-LINC01419 affected LUAD cell proliferation as well as stem cell sphere-formation were examined by CCK-8 and cell sphere-forming assays. In addition, whether LINC01419 could recruit EZH2 and regulate FBP1 expression were determined by bioinformatics analysis, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (ChIP). Western blot was utilized to detect the protein expression levels of FBP1, CD44, CD133, and ALDH-1 as well. RESULTS: On the basis of the findings from those assays, an up-regulation of LINC01419 level was demonstrated in LUAD cell lines, and a remarkable upregulation of it in CD44 + LUAD cells. In LUAD cells, proliferation and stem cell sphere-formation that were attenuated by LINC01419 knockdown were discovered to be facilitated by LINC01419 overexpression. And a binding relationship between LINC01419 and EZH2 was determined by RIP assay. Besides, EZH2 was capable of binding to FBP1 promoter region, as found by ChIP-PCR assay. Finally, it was demonstrated by in vitro experiments that LINC01419 could inhibit FBP1 expression by recruiting EZH2, resulting in promotion of LUAD cell proliferation and stemness. SIGNIFICANCE: To summarize, our findings demonstrate a cancer-promoting role of LINC01419 in LUAD. LINC01419, by recruiting EZH2 and regulating FBP1 expression, contributes to LUAD cell stemness. According to these findings, the potential of LINC01419 to be the target for LUAD treatment is hence determined, which also adds more possibility to the enrichment of therapeutic strategies for lung cancer stem cells.

Epigenetic regulation of Fructose-1,6-bisphosphatase 1 by host transcription factor Speckled 110 kDa during hepatitis B virus infection.

Hepatitis B virus (HBV) is the leading cause of liver disease ranging from acute and chronic hepatitis to liver cirrhosis and hepatocellular carcinoma (HCC). Studies have revealed that HBV infection broadly reprogrammes the host cellular metabolic processes for viral pathogenesis. Previous reports have shown that glycolysis and gluconeogenesis are among the most deregulated pathways during HBV infection. We noted that despite being one of the rate-limiting enzymes of gluconeogenesis, the role and regulation of Fructose-1,6-bisphosphatase 1 (FBP1) during HBV infection is not much explored. In this study, we report FBP1 upregulation upon HBV infection and unravel a novel mechanism of epigenetic reprogramming of FBP1 by HBV via utilizing host factor Speckled 110 kDa (Sp110). Here, we identified acetylated lysine 18 of histone H3 (H3K18Ac) as a selective interactor of Sp110 Bromodomain. Furthermore, we found that Sp110 gets recruited on H3K18Ac-enriched FBP1 promoter, and facilitates recruitment of deacetylase Sirtuin 2 (SIRT2) on that site in the presence of HBV. SIRT2 in turn brings its interactor and transcriptional activator Hepatocyte nuclear factor 4-alpha to the promoter, which ultimately leads to a loss of DNA methylation near the cognate site. Interestingly, this Sp110 driven FBP1 regulation during infection was found to promote viral-borne HCC progression. Moreover, Sp110 can be used as a prognostic marker for the hepatitis-mediated HCC patients, where high Sp110 expression significantly lowered their survival. Thus, the epigenetic reader protein Sp110 has potential to be a therapeutic target to challenge HBV-induced HCCs.