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1.
Sci Rep ; 14(1): 10178, 2024 05 03.
Article in English | MEDLINE | ID: mdl-38702410

ABSTRACT

The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome has been associated with worse outcomes from severe traumatic brain injury (TBI). The NLRP3 inflammasome is also strongly associated with other pro-inflammatory conditions, such as obesity. Little is known about the potential effect of mild TBI (mTBI) on the NLRP3 inflammasome and the extent to which modifying factors, such as obesity, may augment the inflammatory response to mTBI. The purpose of this study was to evaluate the association of NLRP3 inflammasome proteins with obese body mass index (BMI ≥ 30) within 24 h of mTBI after presenting to a level 1 trauma center emergency department. This is a secondary analysis of prospectively enrolled patients with mTBI who presented to the emergency department of one U.S. Level 1 trauma center from 2013 to 2018 (n = 243). A series of regression models were built to evaluate the association of NLRP3 proteins obtained from blood plasma within 24 h of injury and BMI as well as the potential interaction effect of higher BMI with NLRP3 proteins (n = 243). A logistic regression model revealed a significant association between IL-18 (p < 0.001) in mTBI patients with obese BMI compared to mTBI patients with non-obese BMI (< 30). Moderation analyses revealed statistically significant interaction effects between apoptotic speck-like protein (ASC), caspase-1, IL-18, IL-1ß and obese BMI which worsened symptom burden, quality of life, and physical function at 2 weeks and 6 months post-injury. Higher acute concentrations of IL-1ß in the overall cohort predicted higher symptoms at 6-months and worse physical function at 2-weeks and 6-months. Higher acute concentrations of IL-18 in the overall cohort predicted worse physical function at 6-months. In this single center mTBI cohort, obese BMI interacted with higher acute concentrations of NLRP3 inflammasome proteins and worsened short- and long-term clinical outcomes.


Subject(s)
Body Mass Index , Brain Concussion , Inflammasomes , Interleukin-18 , NLR Family, Pyrin Domain-Containing 3 Protein , Obesity , Humans , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Male , Female , Obesity/complications , Inflammasomes/metabolism , Adult , Middle Aged , Brain Concussion/complications , Brain Concussion/blood , Interleukin-18/blood , Interleukin-18/metabolism , Prospective Studies , Interleukin-1beta/blood , Interleukin-1beta/metabolism , Caspase 1/metabolism
2.
3 Biotech ; 13(7): 230, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37309406

ABSTRACT

The present investigation was envisaged for large scale in-silico genome wide identification and characterization of glutathione S-transferases (GSTs) in Chenopodium quinoa. In this study, a total of 120 GST genes (CqGSTs) were identified and divided into 11 classes of which tau and phi were highest in numbers. The average protein length of protein was found to be 279.06 with their corresponding average molecular weight of 31,819.4 kDa. The subcellular localization analysis results showed that proteins were centrally localized in the cytoplasm followed by chloroplast, mitochondria and plastids. Structural analysis revealed the presence of 2 -14 exons in CqGST genes. Most of the proteins possessed two exon one intron organization. MEME analysis identified 15 significantly conserved motifs with a width of 6-50 amino acids. Motifs 1, 3, 2, 5, 6, 8, 9 and 13 were found specifically in tau class family; motifs 3, 4, 5, 6, 7 and 9 were found in phi class gene family, while motifs 3, 4, 13 and 14 were found in metaxin class. Multiple sequence alignment revealed highly conserved N-terminus with active site serine (Ser; S) or cysteine (Cys; C) residue for the activation of GSH binding and GST catalytic activity. The gene loci were found to be unevenly distributed across 18 different chromosomes with a maximum of 17 genes located on chromosome number 7. Dominance of alpha helix was followed by coil, extended strand and beta turns. Gene duplication analysis revealed that segmental duplication and purifying type selection were highest in number and found to be main source of expansion of GST gene family. Cis acting regulatory elements analysis showed the presence of 21 different elements involved in stress, hormone and light response and cellular development. The evolutionary relationship of CqGST proteins carried out using maximum likelihood method revealed that all the tau and phi class GSTs were closely associated with those of G. max, O. sativa and A. thaliana. Molecular docking of GST molecules with the fungicide metalaxyl showed that the CqGSTF1 had the lowest binding energy. The comprehensive study of CqGST gene family in quinoa provides groundwork for further functional analysis of CqGST genes in the species at molecular level and has potential applications in plant breeding.

3.
J Plant Res ; 135(6): 823-852, 2022 Nov.
Article in English | MEDLINE | ID: mdl-36066757

ABSTRACT

Plant glutathione S-transferases are an ancient protein superfamily having antioxidant activity. These proteins are primarily involved in diverse plant functions such as plant growth and development, secondary metabolism, signaling pathways and defense against biotic and abiotic stresses. The current study aimed to comprehensively identify and characterize the GST gene family in the medicinally important crop Papaver somniferum. A total of 93 GST proteins were identified belonging to eight GST classes and found to be majorly localized in the cytoplasm. All GST genes were found on eleven opium chromosomes. Gene duplication analysis showed segmental duplication as a key factor for opium GST gene family expansion under strong purifying selection. Phylogenetic analysis with gymnosperm, angiosperm and bryophyte revealed the evolution of GSTs earlier than their division into separate groups and also prior to the divergence of monocot and dicot. The secondary structure prediction showed the dominance of α-helices indicative of PsomGSTs as structurally stable and elastic proteins. Gene architecture showed the conservation of number of exons across the classes. MEME analysis revealed only a few class specific and many across class conserved motifs. Ser was found to be the active site residue of tau, phi, theta and zeta class and Cys was catalytic residue of DHAR, lambda and GHR class. Promoter analyses identified many cis-acting regulatory elements related to hormonal, cellular, stress and light response functions. Ser was the key phosphorylation site. Only three glycosylation sites were found across the 93 PsomGSTs. 3D structure prediction was also performed and was validated. Interactome analyses revealed the correlation of PsomGSTs with glutathione metabolizing proteins. Gene enrichment analysis and KEGG pathway analyzed the involvement of PsomGSTs in three major pathways i.e. glutathione metabolism, tyrosine metabolism and ascorbate metabolism. The outcome revealed high model quality of PsomGSTs. The results of the current study will be of potential significance to understand the functional and structural importance of the GST gene family in opium, a medicinally important crop.


Subject(s)
Glutathione Transferase , Papaver , Glutathione Transferase/genetics , Glutathione Transferase/chemistry , Glutathione Transferase/metabolism , Gene Expression Regulation, Plant , Papaver/genetics , Papaver/metabolism , Phylogeny , Opium , Plants/genetics , Glutathione/metabolism
4.
J Appl Genet ; 63(4): 609-631, 2022 Dec.
Article in English | MEDLINE | ID: mdl-35689012

ABSTRACT

Glutathione S-transferases are a multifunctional protein superfamily that is involved in diverse plant functions such as defense mechanisms, signaling, stress response, secondary metabolism, and plant growth and development. Although the banana whole-genome sequence is available, the distribution of GST genes on banana chromosomes, their subcellular localization, gene structure, their evolutionary relation with each other, conserved motifs, and their roles in banana are still unknown. A total of 62 full-length GST genes with the canonical thioredoxin fold have been identified belonging to nine GST classes, namely tau, phi, theta, zeta, lambda, DHAR, EF1G, GHR, and TCHQD. The 62 GST genes were distributed into 11 banana chromosomes. All the MaGSTs were majorly localized in the cytoplasm. Gene architecture showed the conservation of exon numbers in individual GST classes. Multiple Em for Motif Elicitation analyses revealed few class-specific motifs and many motifs were found in all the GST classes. Multiple sequence alignment of banana GST amino acid sequences with rice, Arabidopsis, and soybean sequences revealed the Ser and Cys as conserved catalytic residues. Gene duplication analyses showed the tandem duplication as a driving force for GST gene family expansion in banana. Cis-regulatory element analysis showed the dominance of light-responsive element followed by stress- and hormone-responsive elements. Expression profiling analyses were also done by RNA-seq data. It was observed that MaGSTs are involved in various stages of fruit development. MaGSTU1 was highly upregulated. The comprehensive and organized studies of MaGST gene family provide groundwork for further functional analysis of MaGST genes in banana at molecular level and further for plant breeding approaches.


Subject(s)
Arabidopsis , Musa , Musa/genetics , Musa/metabolism , Glutathione Transferase/genetics , Glutathione Transferase/chemistry , Glutathione Transferase/metabolism , Gene Expression Regulation, Plant , Plant Proteins/genetics , Fruit/genetics , Fruit/metabolism , Stress, Physiological/genetics , Phylogeny , Plant Breeding , Arabidopsis/genetics , Gene Expression Profiling
5.
Curr Dev Nutr ; 5(4): nzab028, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33948532

ABSTRACT

BACKGROUND: Double-fortified salt (DFS) with iron and iodine has been demonstrated to be efficacious but questions of unintended effects on the gains in salt iodization remain. The main cross-sectional study based on the use of DFS over 1 y showed a reduction in iron deficiency risk. Whether the programs and the levels of added iron can adversely affect iodine status is yet to be established. OBJECTIVES: We hypothesized that the addition of iron to iodized salt can adversely affect iodine status in women of reproductive age (WRA). METHODS: A cross-sectional substudy was conducted in 4 matched-pair adjacent districts of rural Uttar Pradesh, India, in 2019. Under the public distribution system (PDS), DFS was available for 1 y through Fair Price Shops, in the 2 DFS supply districts (DFS-SDs). In these districts, iodized salt was also available in the market. In the 2 compared DFS nonsupply districts (DFS-NSDs), only iodized salt was available. In the substudy, participants included WRA (n = 1624) residing in rural areas of the selected districts. Iodine content in urine and salt samples was measured in each of the groups. RESULTS: Significantly fewer women from the DFS-SDs had median urinary iodine concentration values indicative of moderate to mild iodine deficiency compared with the women from the DFS-NSDs. The salt purchase pattern and iodine content revealed that significantly fewer (21.99%) households in the DFS-SDs were purchasing inadequately iodized crystal salt, compared with 36.04% households in the DFS-NSDs. CONCLUSIONS: The data reject the working hypothesis and suggest a beneficial effect of the DFS program on the iodine status in WRA, thereby supporting a recommendation of DFS supply through the PDS.

6.
3 Biotech ; 10(7): 321, 2020 Jul.
Article in English | MEDLINE | ID: mdl-32656054

ABSTRACT

Glutathione-S transferase (GST) is a most ancient protein superfamily of multipurpose roles and evolved principally from gene duplication of an ancestral GSH binding protein. They have implemented in diverse plant functions such as detoxification of xenobiotic, secondary metabolism, growth and development, and majorly against biotic and abiotic stresses. The vital structural features of GSTs like highly divergent functional topographies, conserved integrated architecture with separate binding pockets for substrates and ligand, the stringent structural fidelity with high Tm values (50º-60º), and stress-responsive cis-regulatory elements in the promoter region offer this protein as most flexible plant protein for plant breeding approaches, biotechnological applications, etc. This review article summarizes the recent information of GST evolution, and their distribution and structural features with emphasis on the assorted roles of Ser and Cys GSTs with the signature motifs in their active sites, alongside their recent biotechnological application in the area of agriculture, environment, and nanotechnology have been highlighted.

7.
Front Plant Sci ; 11: 603380, 2020.
Article in English | MEDLINE | ID: mdl-33510748

ABSTRACT

Sessile plants possess an assembly of signaling pathways that perceive and transmit environmental signals, ultimately resulting in transcriptional reprogramming. Histone is a key feature of chromatin structure. Numerous histone-modifying proteins act under different environmental stress conditions to help modulate gene expression. DNA methylation and histone modification are crucial for genome reprogramming for tissue-specific gene expression and global gene silencing. Different classes of chromatin remodelers including SWI/SNF, ISWI, INO80, and CHD are reported to act upon chromatin in different organisms, under diverse stresses, to convert chromatin from a transcriptionally inactive to a transcriptionally active state. The architecture of chromatin at a given promoter is crucial for determining the transcriptional readout. Further, the connection between somatic memory and chromatin modifications may suggest a mechanistic basis for a stress memory. Studies have suggested that there is a functional connection between changes in nuclear organization and stress conditions. In this review, we discuss the role of chromatin architecture in different stress responses and the current evidence on somatic, intergenerational, and transgenerational stress memory.

8.
Genome ; 61(5): 311-322, 2018 May.
Article in English | MEDLINE | ID: mdl-29447453

ABSTRACT

Plant glutathione S-transferases (GSTs) are integral to normal plant metabolism and biotic and abiotic stress tolerance. The GST gene family has been characterized in diverse plant species using molecular biology and bioinformatics approaches. In the current study, in silico analysis identified 44 GSTs in Vigna radiata. Of the total 44 GSTs identified, chromosomal locations of 31 GSTs were confirmed. The pI value of GST proteins ranged from 5.10 to 9.40. The predicted molecular weights ranged from 13.12 to 50 kDa. Subcellular localization analysis revealed that all GSTs were predominantly localized in the cytoplasm. The active site amino acids were confirmed to be serine in tau, phi, theta, zeta, and TCHQD; cysteine in lambda, DHAR, and omega; and tyrosine in EF1G. The gene architecture conformed to the two-exon/one-intron and three-exon/two-intron organization in the case of tau and phi classes, respectively. MEME analysis identified 10 significantly conserved motifs with the width of 8-50 amino acids. The motifs identified were either specific to a specific GST class or were shared by multiple GST classes. The results of the current study will be of potential importance in the characterization of the GST gene family in V. radiata, an economically important leguminous crop.


Subject(s)
Chromosomes, Plant/chemistry , Gene Expression Regulation, Plant , Glutathione Transferase/genetics , Plant Proteins/genetics , Vigna/genetics , Amino Acid Sequence , Catalytic Domain , Chromosome Mapping , Chromosomes, Plant/ultrastructure , Computational Biology/methods , Exons , Gene Ontology , Glutathione Transferase/metabolism , Introns , Isoenzymes/genetics , Isoenzymes/metabolism , Molecular Sequence Annotation , Molecular Weight , Phylogeny , Plant Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Vigna/classification , Vigna/enzymology
9.
Oncotarget ; 7(21): 30379-95, 2016 May 24.
Article in English | MEDLINE | ID: mdl-27105497

ABSTRACT

Establishing c-Myc's (Myc) role in liver regeneration has proven difficult particularly since the traditional model of partial hepatectomy may provoke an insufficiently demanding proliferative stress. We used a model of hereditary tyrosinemia whereby the affected parenchyma can be gradually replaced by transplanted hepatocytes, which replicate 50-100-fold, over several months. Prior to transplantation, livers from myc-/- (KO) mice were smaller in young animals and larger in older animals relative to myc+/+ (WT) counterparts. KO mice also consumed more oxygen, produced more CO2 and generated more heat. Although WT and KO hepatocytes showed few mitochondrial structural differences, the latter demonstrated defective electron transport chain function. RNAseq revealed differences in transcripts encoding ribosomal subunits, cytochrome p450 members and enzymes for triglyceride and sterol biosynthesis. KO hepatocytes also accumulated neutral lipids. WT and KO hepatocytes repopulated recipient tyrosinemic livers equally well although the latter were associated with a pro-inflammatory hepatic environment that correlated with worsening lipid accumulation, its extracellular deposition and parenchymal oxidative damage. Our results show Myc to be dispensable for sustained in vivo hepatocyte proliferation but necessary for maintaining normal lipid homeostasis. myc-/- livers resemble those encountered in non-alcoholic fatty liver disease and, under sustained proliferative stress, gradually acquire the features of non-alcoholic steatohepatitis.


Subject(s)
Hepatocytes/metabolism , Lipid Metabolism/genetics , Liver Regeneration , Proto-Oncogene Proteins c-myc/genetics , Animals , Cell Proliferation , Cell Size , Cells, Cultured , Gene Expression Profiling/methods , Hepatocytes/cytology , Hepatocytes/transplantation , Liver/cytology , Liver/metabolism , Mice, Inbred C57BL , Mice, Knockout , Mitochondria/genetics , Mitochondria/metabolism , Mitochondrial Proteins/genetics , Mitochondrial Proteins/metabolism , Non-alcoholic Fatty Liver Disease/genetics , Non-alcoholic Fatty Liver Disease/metabolism , Proto-Oncogene Proteins c-myc/metabolism , Triglycerides/metabolism
10.
Endocrinology ; 156(10): 3610-24, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26196542

ABSTRACT

Emerging evidence suggests that impaired regulation of adipocyte lipolysis contributes to the proinflammatory immune cell infiltration of metabolic tissues in obesity, a process that is proposed to contribute to the development and exacerbation of insulin resistance. To test this hypothesis in vivo, we generated mice with adipocyte-specific deletion of adipose triglyceride lipase (ATGL), the rate-limiting enzyme catalyzing triacylglycerol hydrolysis. In contrast to previous models, adiponectin-driven Cre expression was used for targeted ATGL deletion. The resulting adipocyte-specific ATGL knockout (AAKO) mice were then characterized for metabolic and immune phenotypes. Lean and diet-induced obese AAKO mice had reduced adipocyte lipolysis, serum lipids, systemic lipid oxidation, and expression of peroxisome proliferator-activated receptor alpha target genes in adipose tissue (AT) and liver. These changes did not increase overall body weight or fat mass in AAKO mice by 24 weeks of age, in part due to reduced expression of genes involved in lipid uptake, synthesis, and adipogenesis. Systemic glucose and insulin tolerance were improved in AAKO mice, primarily due to enhanced hepatic insulin signaling, which was accompanied by marked reduction in diet-induced hepatic steatosis as well as hepatic immune cell infiltration and activation. In contrast, although adipocyte ATGL deletion reduced AT immune cell infiltration in response to an acute lipolytic stimulus, it was not sufficient to ameliorate, and may even exacerbate, chronic inflammatory changes that occur in AT in response to diet-induced obesity.


Subject(s)
Adipocytes/metabolism , Inflammation/genetics , Insulin Resistance/genetics , Lipase/genetics , Obesity/genetics , Adipose Tissue/metabolism , Animals , Antigens, Differentiation/genetics , Antigens, Differentiation/metabolism , CD11c Antigen/genetics , CD11c Antigen/metabolism , Dendritic Cells/metabolism , Diet, High-Fat/adverse effects , Gene Expression , Immunoblotting , Inflammation/blood , Inflammation/metabolism , Lipase/metabolism , Lipid Metabolism/genetics , Lipids/blood , Lipolysis/genetics , Liver/metabolism , Macrophages/metabolism , Mice, 129 Strain , Mice, Inbred C57BL , Mice, Knockout , Obesity/etiology , Obesity/metabolism , Reverse Transcriptase Polymerase Chain Reaction
11.
Am J Physiol Endocrinol Metab ; 308(10): E879-90, 2015 May 15.
Article in English | MEDLINE | ID: mdl-25783895

ABSTRACT

Adipose triglyceride lipase (ATGL) is the rate-limiting enzyme mediating triacylglycerol hydrolysis in virtually all cells, including adipocytes and skeletal myocytes, and hence, plays a critical role in mobilizing fatty acids. Global ATGL deficiency promotes skeletal myopathy and exercise intolerance in mice and humans, and yet the tissue-specific contributions to these phenotypes remain unknown. The goal of this study was to determine the relative contribution of ATGL-mediated triacylglycerol hydrolysis in adipocytes vs. skeletal myocytes to acute exercise performance. To achieve this goal, we generated murine models with adipocyte- and skeletal myocyte-specific targeted deletion of ATGL. We then subjected untrained mice to acute peak and submaximal exercise interventions and assessed exercise performance and energy substrate metabolism. Impaired ATGL-mediated lipolysis within adipocytes reduced peak and submaximal exercise performance, reduced peripheral energy substrate availability, shifted energy substrate preference toward carbohydrate oxidation, and decreased HSL Ser(660) phosphorylation and mitochondrial respiration within skeletal muscle. In contrast, impaired ATGL-mediated lipolysis within skeletal myocytes was not sufficient to reduce peak and submaximal exercise performance or peripheral energy substrate availability and instead tended to enhance metabolic flexibility during peak exercise. Furthermore, the expanded intramyocellular triacylglycerol pool in these mice was reduced following exercise in association with preserved HSL phosphorylation, suggesting that HSL may compensate for impaired ATGL action in skeletal muscle during exercise. These data suggest that adipocyte rather than skeletal myocyte ATGL-mediated lipolysis plays a greater role during acute exercise in part because of compensatory mechanisms that maintain lipolysis in muscle, but not adipose tissue, when ATGL is absent.


Subject(s)
Adipocytes/metabolism , Lipase/genetics , Muscle Fibers, Skeletal/metabolism , Physical Conditioning, Animal/physiology , Physical Exertion/genetics , Animals , Athletic Performance , Exercise Tolerance/genetics , Female , Gene Deletion , Lipase/metabolism , Lipolysis/genetics , Male , Mice , Mice, Inbred C57BL , Mice, Knockout
12.
J Plant Physiol ; 171(7): 486-96, 2014 Apr 15.
Article in English | MEDLINE | ID: mdl-24655384

ABSTRACT

Abiotic stresses affect plant growth, metabolism and sustainability in a significant way and hinder plant productivity. Plants combat these stresses in myriad ways. The analysis of the mechanisms underlying abiotic stress tolerance has led to the identification of a highly complex, yet tightly regulated signal transduction pathway consisting of phosphatases, kinases, transcription factors and other regulatory elements. It is becoming increasingly clear that also epigenetic processes cooperate in a concerted manner with ABA-mediated gene expression in combating stress conditions. Dynamic stress-induced mechanisms, involving changes in the apoplastic pool of ABA, are transmitted by a chain of phosphatases and kinases, resulting in the expression of stress inducible genes. Processes involving DNA methylation and chromatin modification as well as post transcriptional, post translational and epigenetic control mechanisms, forming multiple tiers of regulation, regulate this gene expression. With recent advances in transgenic technology, it has now become possible to engineer plants expressing stress-inducible genes under the control of an inducible promoter, enhancing their ability to withstand adverse conditions. This review briefly discusses the synthesis of ABA, components of the ABA signal transduction pathway and the plants' responses at the genetic and epigenetic levels. It further focuses on the role of RNAs in regulating stress responses and various approaches to develop stress-tolerant transgenic plants.


Subject(s)
Abscisic Acid/metabolism , Epigenesis, Genetic , Gene Expression Regulation, Plant , Plant Physiological Phenomena , Signal Transduction , Stress, Physiological/genetics , Plant Proteins/genetics , Plant Proteins/metabolism , Plants, Genetically Modified/genetics , Plants, Genetically Modified/metabolism , RNA, Plant/genetics , RNA, Plant/metabolism
13.
Diabetes ; 62(10): 3350-61, 2013 Oct.
Article in English | MEDLINE | ID: mdl-23835334

ABSTRACT

Intramyocellular triacylglycerol (IMTG) accumulation is highly associated with insulin resistance and metabolic complications of obesity (lipotoxicity), whereas comparable IMTG accumulation in endurance-trained athletes is associated with insulin sensitivity (the athlete's paradox). Despite these findings, it remains unclear whether changes in IMTG accumulation and metabolism per se influence muscle-specific and systemic metabolic homeostasis and insulin responsiveness. By mediating the rate-limiting step in triacylglycerol hydrolysis, adipose triglyceride lipase (ATGL) has been proposed to influence the storage/production of deleterious as well as essential lipid metabolites. However, the physiological relevance of ATGL-mediated triacylglycerol hydrolysis in skeletal muscle remains unknown. To determine the contribution of IMTG hydrolysis to tissue-specific and systemic metabolic phenotypes in the context of obesity, we generated mice with targeted deletion or transgenic overexpression of ATGL exclusively in skeletal muscle. Despite dramatic changes in IMTG content on both chow and high-fat diets, modulation of ATGL-mediated IMTG hydrolysis did not significantly influence systemic energy, lipid, or glucose homeostasis, nor did it influence insulin responsiveness or mitochondrial function. These data argue against a role for altered IMTG accumulation and lipolysis in muscle insulin resistance and metabolic complications of obesity.


Subject(s)
Adipose Tissue/metabolism , Insulin Resistance , Intracellular Signaling Peptides and Proteins/metabolism , Muscle, Skeletal/metabolism , Obesity/metabolism , Triglycerides/metabolism , Animals , Diet, High-Fat , Energy Metabolism , Homeostasis , Hydrolysis , Insulin Resistance/physiology , Lipid Metabolism , Mice , Mice, Knockout , Mice, Transgenic , Phenotype , Phosphorylation
14.
Diabetes ; 61(8): 2004-15, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22586588

ABSTRACT

Glucose stimulates rodent and human ß-cell replication, but the intracellular signaling mechanisms are poorly understood. Carbohydrate response element-binding protein (ChREBP) is a lipogenic glucose-sensing transcription factor with unknown functions in pancreatic ß-cells. We tested the hypothesis that ChREBP is required for glucose-stimulated ß-cell proliferation. The relative expression of ChREBP was determined in liver and ß-cells using quantitative RT-PCR (qRT-PCR), immunoblotting, and immunohistochemistry. Loss- and gain-of-function studies were performed using small interfering RNA and genetic deletion of ChREBP and adenoviral overexpression of ChREBP in rodent and human ß-cells. Proliferation was measured by 5-bromo-2'-deoxyuridine incorporation, [(3)H]thymidine incorporation, and fluorescence-activated cell sorter analysis. In addition, the expression of cell cycle regulatory genes was measured by qRT-PCR and immunoblotting. ChREBP expression was comparable with liver in mouse pancreata and in rat and human islets. Depletion of ChREBP decreased glucose-stimulated proliferation in ß-cells isolated from ChREBP(-/-) mice, in INS-1-derived 832/13 cells, and in primary rat and human ß-cells. Furthermore, depletion of ChREBP decreased the glucose-stimulated expression of cell cycle accelerators. Overexpression of ChREBP amplified glucose-stimulated proliferation in rat and human ß-cells, with concomitant increases in cyclin gene expression. In conclusion, ChREBP mediates glucose-stimulated proliferation in pancreatic ß-cells.


Subject(s)
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/physiology , Glucose/pharmacology , Insulin-Secreting Cells/drug effects , Nuclear Proteins/physiology , Transcription Factors/physiology , Animals , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/biosynthesis , Cell Cycle Proteins/physiology , Cell Proliferation/drug effects , Humans , Insulin-Secreting Cells/metabolism , Insulinoma/metabolism , Mice , Rats
15.
J Lipid Res ; 52(2): 318-29, 2011 Feb.
Article in English | MEDLINE | ID: mdl-21068004

ABSTRACT

PNPLA3 (adiponutrin, calcium-independent phospholipase A(2) epsilon [iPLA(2)ε]) is an adipose-enriched, nutritionally regulated protein that belongs to the patatin-like phospholipase domain containing (PNPLA) family of lipid metabolizing proteins. Genetic variations in the human PNPLA3 gene (i.e., the rs738409 I148M allele) has been strongly and repeatedly associated with fatty liver disease. Although human PNPLA3 has triacylglycerol (TAG) hydrolase and transacylase activities in vitro, its in vivo function and physiological relevance remain controversial. The objective of this study was to determine the metabolic consequences of global targeted deletion of the Pnpla3 gene in mice. We found that Pnpla3 mRNA expression is altered in adipose tissue and liver in response to acute and chronic nutritional challenges. However, global targeted deletion of the Pnpla3 gene in mice did not affect TAG hydrolysis, nor did it influence energy/glucose/lipid homoeostasis or hepatic steatosis/injury. Experimental interventions designed to increase Pnpla3 expression (refeeding, high-sucrose diet, diet-induced obesity, and liver X receptor agonism) likewise failed to reveal differences in the above-mentioned metabolic phenotypes. Expression of the Pnpla3 paralog, Pnpla5, was increased in adipose tissue but not in liver of Pnpla3-deficient mice, but compensatory regulation of genes involved in TAG metabolism was not identified. Together these data argue against a role for Pnpla3 loss-of-function in fatty liver disease or metabolic syndrome in mice.


Subject(s)
Fatty Liver/metabolism , Metabolic Syndrome/metabolism , Phospholipases A2, Calcium-Independent/deficiency , Adipose Tissue/metabolism , Animals , Energy Metabolism , Fatty Liver/etiology , Male , Metabolic Syndrome/etiology , Mice , Mice, Knockout , Triglycerides/metabolism
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