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Biochemical and Biophysical Research... May 2024At present, the physiological roles of various hormones in fish glucose metabolism have been elucidated. Spexin, a 14-amino acids polypeptide, is highly conserved in...
At present, the physiological roles of various hormones in fish glucose metabolism have been elucidated. Spexin, a 14-amino acids polypeptide, is highly conserved in many species and has functions such as reducing body weight and improving insulin resistance. In this paper, the open reading frame (ORF) of spx2 in grass carp (Ctenopharyngodon idella) was cloned, and the tissue distribution of spx1 and spx2, their direct and indirect regulatory effects on glucose metabolism of grass carp were investigated. The ORF of spx2 gene in grass carp was 279 bp in length. Moreover, spx1 was highly expressed in the adipose tissue, while spx2 was highly expressed in the brain. In vitro, SPX1 and SPX2 showed opposite effects on the glycolytic pathway in the primary hepatocytes. In vivo, intraperitoneal injection of SPX1 and SPX2 significantly reduced serum glucose levels and increased hepatopancreas glycogen contents. Meanwhile, SPX1 and SPX2 promoted the expression of key genes of glycolysis (pk) and glycogen synthesis (gys) in the hepatopancreas at 3 h post injection. As for indirect effects, 1000 nM SPX1 and SPX2 significantly increased insulin-mediated liver type phosphofructokinase (pfkla) mRNA expression and enhanced the inhibitory effects of insulin on glucose-6-phosphatase (g6pase), phosphoenolpyruvate carboxykinase (pepck), glycogen phosphorylase L (pygl) mRNA expression. Our results show that SPX1 and SPX2 have similar indirect effects on the regulation of glucose metabolism that enhance insulin activity, but they exhibit opposite roles in terms of direct effects.
Topics: Animals; Glucose; Carps; Insulin; RNA, Messenger; Glycogen; Fish Proteins
PubMed: 38531222
DOI: 10.1016/j.bbrc.2024.149810 -
Basic Research in Cardiology Jun 2024Decreased nicotinamide adenine dinucleotide (NAD) levels contribute to various pathologies such as ageing, diabetes, heart failure and ischemia-reperfusion injury (IRI)....
Decreased nicotinamide adenine dinucleotide (NAD) levels contribute to various pathologies such as ageing, diabetes, heart failure and ischemia-reperfusion injury (IRI). Nicotinamide riboside (NR) has emerged as a promising therapeutic NAD precursor due to efficient NAD elevation and was recently shown to be the only agent able to reduce cardiac IRI in models employing clinically relevant anesthesia. However, through which metabolic pathway(s) NR mediates IRI protection remains unknown. Furthermore, the influence of insulin, a known modulator of cardioprotective efficacy, on the protective effects of NR has not been investigated. Here, we used the isolated mouse heart allowing cardiac metabolic control to investigate: (1) whether NR can protect the isolated heart against IRI, (2) the metabolic pathways underlying NR-mediated protection, and (3) whether insulin abrogates NR protection. NR protection against cardiac IRI and effects on metabolic pathways employing metabolomics for determination of changes in metabolic intermediates, and C-glucose fluxomics for determination of metabolic pathway activities (glycolysis, pentose phosphate pathway (PPP) and mitochondrial/tricarboxylic acid cycle (TCA cycle) activities), were examined in isolated C57BL/6N mouse hearts perfused with either (a) glucose + fatty acids (FA) ("mild glycolysis group"), (b) lactate + pyruvate + FA ("no glycolysis group"), or (c) glucose + FA + insulin ("high glycolysis group"). NR increased cardiac NAD in all three metabolic groups. In glucose + FA perfused hearts, NR reduced IR injury, increased glycolytic intermediate phosphoenolpyruvate (PEP), TCA intermediate succinate and PPP intermediates ribose-5P (R5P) / sedoheptulose-7P (S7P), and was associated with activated glycolysis, without changes in TCA cycle or PPP activities. In the "no glycolysis" hearts, NR protection was lost, whereas NR still increased S7P. In the insulin hearts, glycolysis was largely accelerated, and NR protection abrogated. NR still increased PPP intermediates, with now high C-labeling of S7P, but NR was unable to increase metabolic pathway activities, including glycolysis. Protection by NR against IRI is only present in hearts with low glycolysis, and is associated with activation of glycolysis. When activation of glycolysis was prevented, through either examining "no glycolysis" hearts or "high glycolysis" hearts, NR protection was abolished. The data suggest that NR's acute cardioprotective effects are mediated through glycolysis activation and are lost in the presence of insulin because of already elevated glycolysis.
Topics: Animals; Pyridinium Compounds; Glycolysis; Mice, Inbred C57BL; Insulin; Myocardial Reperfusion Injury; Niacinamide; Male; Myocardium; Mice; Isolated Heart Preparation; Metabolomics; NAD; Disease Models, Animal; Citric Acid Cycle
PubMed: 38528175
DOI: 10.1007/s00395-024-01042-4 -
Journal of Food and Drug Analysis Dec 2023Adlay (Coix lachryma-jobi L.) is a traditional Chinese herbal medicine with various biological activities. We investigated the anti-diabetic effects of different parts...
Adlay (Coix lachryma-jobi L.) is a traditional Chinese herbal medicine with various biological activities. We investigated the anti-diabetic effects of different parts of adlay seeds, including polished adlay (PA), adlay bran (AB) and dehulled adlay (DA) in a streptozotocin (STZ)/high fat diet (HFD) diabetic rat model (DM). DM rats supplemented with or without PA (43%), AB (3%), or DA (46%) diet for 8 weeks. The plasma glucose and insulin levels and the insulin resistance index (HOMA-IR) were increased in DM group; among the three adlay diets, DA has the best effects attenuating all of these alterations in DM rats. Both AB and DA alleviated diabetes-impaired glucose tolerance. The increased hepatic phosphoenolpyruvate carboxykinase protein expression in DM group was improved by all of the three adlay diets. The increased ratio of glucose-6-phosphatase to glucokinase in DM group was suppressed by DA supplementation, further suggesting DA diet is most effective among the three diets. Both AB and DA diets had beneficial effects against hepatic steatosis, with better effects observed in DA group. These results suggest that the DA diet, composed of both polished adlay and adlay bran, possesses the best potential to improve glucose homeostasis, at least in part, by alleviating hepatic glucose metabolism and steatosis.
Topics: Rats; Animals; Coix; Diet, High-Fat; Streptozocin; Gluconeogenesis; Diabetes Mellitus, Experimental; Fatty Liver
PubMed: 38526822
DOI: 10.38212/2224-6614.3486 -
Genetics and Molecular Biology 2024Photosynthetic phosphoenolpyruvate carboxylase (PEPC) catalyses the irreversible carboxylation of phosphoenolpyruvate (PEP), producing oxaloacetate (OAA). This enzyme...
Photosynthetic phosphoenolpyruvate carboxylase (PEPC) catalyses the irreversible carboxylation of phosphoenolpyruvate (PEP), producing oxaloacetate (OAA). This enzyme catalyses the first step of carbon fixation in C4 photosynthesis, contributing to the high photosynthetic efficiency of C4 plants. PEPC is also involved in replenishing tricarboxylic acid cycle intermediates, such as OAA, being involved in the C/N balance. In plants, PEPCs are classified in two types: bacterial type (BTPC) and plant-type (PTPC), which includes photosynthetic and non-photosynthetic PEPCs. During C4 evolution, photosynthetic PEPCs evolved independently. C4 PEPCs evolved to be highly expressed and active in a spatial-specific manner. Their gene expression pattern is also regulated by developmental cues, light, circadian clock as well as adverse environmental conditions. However, the gene regulatory networks controlling C4 PEPC gene expression, namely its cell-specificity, are largely unknown. Therefore, after an introduction to the evolution of PEPCs, this review aims to discuss the current knowledge regarding the transcriptional regulation of C4 PEPCs, focusing on cell-specific and developmental expression dynamics, light and circadian regulation, as well as response to abiotic stress. In conclusion, this review aims to highlight the evolution, transcriptional regulation by different signals and importance of PEPC in C4 photosynthesis and its potential as tool for crop improvement.
PubMed: 38517370
DOI: 10.1590/1678-4685-GMB-2023-0190 -
Plant Physiology and Biochemistry : PPB Mar 2024Phosphoenolpyruvate carboxylase (PEPC) plays a crucial role in the initial carbon fixation process in C plants. However, its nonphotosynthetic functions in Haloxylon...
Phosphoenolpyruvate carboxylase (PEPC) plays a crucial role in the initial carbon fixation process in C plants. However, its nonphotosynthetic functions in Haloxylon ammodendron, a C perennial xerohalophytic shrub, are still poorly understood. Previous studies have reported the involvement of PEPC in plant responses to abiotic stresses such as drought and salt stress. However, the underlying mechanism of PEPC tolerance to drought stress has not been determined. In this study, we cloned the C-type PEPC gene HaPEPC1 from H. ammodendron and investigated its biological function by generating transgenic Arabidopsis plants with ectopic expression of HaPEPC1. Our results showed that, compared with WT (wild-type) plants, ectopic expression of HaPEPC1 plants exhibited significantly greater germination rates and chlorophyll contents. Furthermore, under drought stress, the transgenic plants presented increased root length, fresh weight, photosynthetic capacity, and antioxidant enzyme activities, particularly ascorbate peroxidase and peroxidase. Additionally, the transgenic plants exhibited reduced levels of malondialdehyde, HO (hydrogen peroxide), and O (superoxide radical). Transcriptome analysis indicated that ectopic expression of HaPEPC1 primarily regulated the expression of genes associated with the stress defence response, glutathione metabolism, and abscisic acid (ABA) synthesis and signalling pathways in response to drought stress. Taken together, these findings suggest that the ectopic expression of HaPEPC1 enhances the reduction of HO and O in transgenic plants, thereby improving reactive oxygen species (ROS) scavenging capacity and enhancing drought tolerance. Therefore, the HaPEPC1 gene holds promise as a candidate gene for crop selection aimed at enhancing drought tolerance.
Topics: Arabidopsis; Droughts; Drought Resistance; Hydrogen Peroxide; Ectopic Gene Expression; Chenopodiaceae; Antioxidants; Plants, Genetically Modified; Stress, Physiological; Gene Expression Regulation, Plant; Plant Proteins
PubMed: 38507839
DOI: 10.1016/j.plaphy.2024.108536 -
Diabetes Jun 2024Diabetes and obesity are risk factors for kidney disease. Whereas renal glucose production increases in diabetes, recent data suggest that gluconeogenic and oxidative...
Diabetes and obesity are risk factors for kidney disease. Whereas renal glucose production increases in diabetes, recent data suggest that gluconeogenic and oxidative capacity decline in kidney disease. Thus, metabolic dysregulation caused by diet-induced insulin resistance may sensitize the kidney for a loss in function. Here, we examined how diet-induced insulin resistance disrupts mitochondrial metabolic fluxes in the renal cortex in vivo. C57BL/6J mice were rendered insulin resistant through high-fat (HF) feeding; anaplerotic, cataplerotic, and oxidative metabolic fluxes in the cortex were quantified through 13C-isotope tracing during a hyperinsulinemic-euglycemic clamp. As expected, HF-fed mice exhibited increased body weight, gluconeogenesis, and systemic insulin resistance compared with chow-fed mice. Relative to the citric acid cycle, HF feeding increased metabolic flux through pyruvate carboxylation (anaplerosis) and phosphoenolpyruvate carboxykinase (cataplerosis) and decreased flux through the pyruvate dehydrogenase complex in the cortex. Furthermore, the relative flux from nonpyruvate sources of acetyl-CoA profoundly increased in the cortex of HF-fed mice, correlating with a marker of oxidative stress. The data demonstrate that HF feeding spares pyruvate from dehydrogenation at the expense of increasing cataplerosis, which may underpin renal gluconeogenesis during insulin resistance; the results also support the hypothesis that dysregulated oxidative metabolism in the kidney contributes to metabolic disease.
Topics: Animals; Diet, High-Fat; Kidney Cortex; Insulin Resistance; Mice, Inbred C57BL; Mice; Gluconeogenesis; Male; Glucose Clamp Technique; Acetyl Coenzyme A; Citric Acid Cycle; Mitochondria
PubMed: 38502790
DOI: 10.2337/db23-0710 -
Applied Microbiology and Biotechnology Mar 2024Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a type of polyhydroxyalkanoates (PHA) that exhibits numerous outstanding properties and is naturally synthesized...
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a type of polyhydroxyalkanoates (PHA) that exhibits numerous outstanding properties and is naturally synthesized and elaborately regulated in various microorganisms. However, the regulatory mechanism involving the specific regulator PhaR in Haloferax mediterranei, a major PHBV production model among Haloarchaea, is not well understood. In our previous study, we showed that deletion of the phosphoenolpyruvate (PEP) synthetase-like (pps-like) gene activates the cryptic phaC genes in H. mediterranei, resulting in enhanced PHBV accumulation. In this study, we demonstrated the specific function of the PPS-like protein as a negative regulator of phaR gene expression and PHBV synthesis. Chromatin immunoprecipitation (ChIP), in situ fluorescence reporting system, and in vitro electrophoretic mobility shift assay (EMSA) showed that the PPS-like protein can bind to the promoter region of phaRP. Computational modeling revealed a high structural similarity between the rifampin phosphotransferase (RPH) protein and the PPS-like protein, which has a conserved ATP-binding domain, a His domain, and a predicted DNA-binding domain. Key residues within this unique DNA-binding domain were subsequently validated through point mutation and functional evaluations. Based on these findings, we concluded that PPS-like protein, which we now renamed as PspR, has evolved into a repressor capable of regulating the key regulator PhaR, and thereby modulating PHBV synthesis. This regulatory network (PspR-PhaR) for PHA biosynthesis is likely widespread among haloarchaea, providing a novel approach to manipulate haloarchaea as a production platform for high-yielding PHA. KEY POINTS: • The repressive mechanism of a novel inhibitor PspR in the PHBV biosynthesis was demonstrated • PspR is widespread among the PHA accumulating haloarchaea • It is the first report of functional conversion from an enzyme to a trans-acting regulator in haloarchaea.
Topics: Polyhydroxyalkanoates; Hydroxybutyrates; DNA; Polyesters
PubMed: 38498113
DOI: 10.1007/s00253-024-13100-x -
Plant, Cell & Environment Jun 2024The repeated emergence of NADP-malic enzyme (ME), NAD-ME and phosphoenolpyruvate carboxykinase (PEPCK) subtypes of C photosynthesis are iconic examples of convergent...
The repeated emergence of NADP-malic enzyme (ME), NAD-ME and phosphoenolpyruvate carboxykinase (PEPCK) subtypes of C photosynthesis are iconic examples of convergent evolution, which suggests that these biochemistries do not randomly assemble, but are instead specific adaptations resulting from unknown evolutionary drivers. Theoretical studies that are based on the classic biochemical understanding have repeatedly proposed light-use efficiency as a possible benefit of the PEPCK subtype. However, quantum yield measurements do not support this idea. We explore this inconsistency here via an analytical model that features explicit descriptions across a seamless gradient between C biochemistries to analyse light harvesting and dark photosynthetic metabolism. Our simulations show that the NADP-ME subtype, operated by the most productive crops, is the most efficient. The NAD-ME subtype has lower efficiency, but has greater light harvesting plasticity (the capacity to assimilate CO in the broadest combination of light intensity and spectral qualities). In both NADP-ME and NAD-ME backgrounds, increasing PEPCK activity corresponds to greater light harvesting plasticity but likely imposed a reduction in photosynthetic efficiency. We draw the first mechanistic links between light harvesting and C subtypes, providing the theoretical basis for future investigation.
Topics: Photosynthesis; Malate Dehydrogenase; Light; Phosphoenolpyruvate Carboxykinase (ATP); Models, Biological
PubMed: 38494958
DOI: 10.1111/pce.14869 -
Antonie Van Leeuwenhoek Mar 2024A new member of the family Flavobacteriaceae (termed Hal144) was isolated from the marine breadcrumb sponge Halichondria panicea. Sponge material was collected in 2018...
A new member of the family Flavobacteriaceae (termed Hal144) was isolated from the marine breadcrumb sponge Halichondria panicea. Sponge material was collected in 2018 at Schilksee which is located in the Kiel Fjord (Baltic Sea, Germany). Phylogenetic analysis of the full-length Hal144 16S rRNA gene sequence revealed similarities from 94.3 to 96.6% to the nearest type strains of the genus Maribacter. The phylogenetic tree of the 16S rRNA gene sequences depicted a cluster of strain Hal144 with its closest relatives Maribacter aestuarii GY20 (96.6%) and Maribacter thermophilus HT7-2 (96.3%). Genome phylogeny showed that Maribacter halichondriae Hal144 branched from a cluster consisting of Maribacter arenosus, Maribacter luteus, and Maribacter polysiphoniae. Genome comparisons of strain Maribacter halichondriae Hal144 with Maribacter sp. type strains exhibited average nucleotide identities in the range of 75-76% and digital DNA-DNA hybridisation values in the range of 13.1-13.4%. Compared to the next related type strains, strain Hal144 revealed unique genomic features such as phosphoenolpyruvate-dependent phosphotransferase system pathway, serine-glyoxylate cycle, lipid A 3-O-deacylase, 3-hexulose-6-phosphate synthase, enrichment of pseudogenes and of genes involved in cell wall and envelope biogenesis, indicating an adaptation to the host. Strain Hal144 was determined to be Gram-negative, mesophilic, strictly aerobic, flexirubin positive, resistant to aminoglycoside antibiotics, and able to utilize N-acetyl-β-D-glucosamine. Optimal growth occurred at 25-30 °C, within a salinity range of 2-6% sea salt, and a pH range between 5 and 8. The major fatty acids identified were C 3-OH, iso-C, and iso-C G. The DNA G + C content of strain Hal144 was 41.4 mol%. Based on the polyphasic approach, strain Hal144 represents a novel species of the genus Maribacter, and we propose the name Maribacter halichondriae sp. nov. The type strain is Hal144 (= DSM 114563 = LMG 32744).
Topics: Animals; Seawater; Phosphatidylethanolamines; Phylogeny; RNA, Ribosomal, 16S; Porifera; DNA, Bacterial; Sequence Analysis, DNA; Bacterial Typing Techniques; Vitamin K 2; Fatty Acids; Flavobacteriaceae
PubMed: 38489089
DOI: 10.1007/s10482-024-01950-4 -
International Journal of Molecular... Feb 2024Many species, which hold a high status and value in traditional Chinese medicine, grow on barks and rocks in the wild, often encountering harsh environments and facing...
Many species, which hold a high status and value in traditional Chinese medicine, grow on barks and rocks in the wild, often encountering harsh environments and facing droughts. However, the molecular mechanisms underlying the shift in the photosynthetic pathway induced by drought remain unclear. To address this issue, three species with different photosynthetic pathways were selected for sequencing and transcriptome data analysis after drought treatment. The findings included 134.43 GB of sequencing data, with numerous Differentially Expressed Genes (DEGs) exhibiting different response mechanisms under drought stress. Gene Ontology (GO)-KEGG-based enrichment analysis of DEGs revealed that metabolic pathways contributed to drought tolerance and alterations in photosynthetic pathways. Phosphoenolpyruvate Carboxylase (PEPC) was subjected to phylogenetic tree construction, sequence alignment, and domain analysis. Under drought stress, variations were observed in the PEPC gene structure and expression among different species; the upregulation of expression may be caused by dof-miR-384, which resulted in the shift from C photosynthesis to CAM, thereby improving drought tolerance in . This study revealed the expression patterns and roles of PEPC genes in enhancing plant drought tolerance and will provide an important basis for in-depth research on 's adaptation mechanisms in arid environments.
Topics: Droughts; Dendrobium; Phylogeny; Transcriptome; Gene Expression Profiling; Photosynthesis; Stress, Physiological; Gene Expression Regulation, Plant
PubMed: 38473979
DOI: 10.3390/ijms25052731