scholarly journals Pro-inflammatory AGE-RAGE signaling is activated during arousal from hibernation in ground squirrel adipose

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4911 ◽  
Author(s):  
Samantha M. Logan ◽  
Kenneth B. Storey
Keyword(s):  
Gene Expression ◽  
Ground Squirrel ◽  
Inflammatory Responses ◽  
Mrna Levels ◽  
Protein Levels ◽  
Ictidomys Tridecemlineatus ◽  
Molecular Pattern ◽  
Brown Adipose ◽  
Dying Cells ◽  
Relative Gene

Background Inflammation is generally suppressed during hibernation, but select tissues (e.g. lung) have been shown to activate both antioxidant and pro-inflammatory pathways, particularly during arousal from torpor when breathing rates increase and oxidative metabolism fueling the rewarming process produces more reactive oxygen species. Brown and white adipose tissues are now understood to be major hubs for the regulation of immune and inflammatory responses, yet how these potentially damaging processes are regulated by fat tissues during hibernation has hardly been studied. The advanced glycation end-product receptor (RAGE) can induce pro-inflammatory responses when bound by AGEs (which are glycated and oxidized proteins, lipids, or nucleic acids) or damage associated molecular pattern molecules (DAMPs, which are released from dying cells). Methods Since gene expression and protein synthesis are largely suppressed during torpor, increases in AGE-RAGE pathway proteins relative to a euthermic control could suggest some role for these pro-inflammatory mediators during hibernation. This study determined how the pro-inflammatory AGE-RAGE signaling pathway is regulated at six major time points of the torpor-arousal cycle in brown and white adipose from a model hibernator, Ictidomys tridecemlineatus. Immunoblotting, RT-qPCR, and a competitive ELISA were used to assess the relative gene expression and protein levels of key regulators of the AGE-RAGE pathway during a hibernation bout. Results The results of this study revealed that RAGE is upregulated as animals arouse from torpor in both types of fat, but AGE and DAMP levels either remain unchanged or decrease. Downstream of the AGE-RAGE cascade, nfat5 was more highly expressed during arousal in brown adipose. Discussion An increase in RAGE protein levels and elevated mRNA levels of the downstream transcription factor nfat5 during arousal suggest the pro-inflammatory response is upregulated in adipose tissue of the hibernating ground squirrel. It is unlikely that this cascade is activated by AGEs or DAMPs. This research sheds light on how a fat-but-fit organism with highly regulated metabolism may control the pro-inflammatory AGE-RAGE pathway, a signaling cascade that is often dysregulated in other obese organisms.

Nitric oxide increases IL-8 gene transcription and mRNA stability to enhance IL-8 gene expression in lung epithelial cells

2004 ◽  
Vol 287 (4) ◽  
pp. L764-L773 ◽  
Author(s):  
Loretta Sparkman ◽  
Vijayakumar Boggaram
Keyword(s):  
Gene Expression ◽  
Nitric Oxide ◽  
Protein Kinase ◽  
Epithelial Cells ◽  
Gene Transcription ◽  
Mrna Stability ◽  
Inflammatory Responses ◽  
Lung Epithelial Cells ◽  
Mrna Levels ◽  
Lung Epithelial

Interleukin (IL)-8, a C-X-C chemokine, is a potent chemoattractant and an activator for neutrophils, T cells, and other immune cells. The airway and respiratory epithelia play important roles in the initiation and modulation of inflammatory responses via production of cytokines and surfactant. The association between elevated levels of nitric oxide (NO) and IL-8 in acute lung injury associated with sepsis, acute respiratory distress syndrome, respiratory syncytial virus infection in infants, and other inflammatory diseases suggested that NO may play important roles in the control of IL-8 gene expression in the lung. We investigated the role of NO in the control of IL-8 gene expression in H441 lung epithelial cells. We found that a variety of NO donors significantly induced IL-8 mRNA levels, and the increase in IL-8 mRNA was associated with an increase in IL-8 protein. NO induction of IL-8 mRNA was due to increases in IL-8 gene transcription and mRNA stability. NO induction of IL-8 mRNA levels was not inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one and KT-5823, inhibitors of soluble guanylate cyclase and protein kinase G, respectively, and 8-bromo-cGMP did not increase IL-8 mRNA levels. This indicated that NO induces IL-8 mRNA levels independently of changes in the intracellular cGMP levels. NO induction of IL-8 mRNA was significantly reduced by inhibitors of extracellular regulated kinase and protein kinase C. IL-8 induction by NO was also reduced by hydroxyl radical scavengers such as dimethyl sulfoxide and dimethylthiourea, indicating the involvement of hydroxyl radicals in the induction process. NO induction of IL-8 gene expression could be a significant contributing factor in the initiation and induction of inflammatory response in the respiratory epithelium.

scholarly journals Kyungheechunggan-Tang-01, a New Herbal Medication, Suppresses LPS-Induced Inflammatory Responses through JAK/STAT Signaling Pathway in RAW 264.7 Macrophages

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Hee-Soo Han ◽  
Eungyeong Jang ◽  
Ji-Sun Shin ◽  
Kyung-Soo Inn ◽  
Jang-Hoon Lee ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Inflammatory Responses ◽  
Inflammatory Diseases ◽  
Molecular Data ◽  
Mrna Levels ◽  
Protein Levels ◽  
Stat3 Phosphorylation ◽  
Stat Signaling ◽  
Cox 2 ◽  
Anti Inflammatory

Medicinal plants have been used as alternative therapeutic tools to alleviate inflammatory diseases. The objective of this study was to evaluate anti-inflammatory properties of Kyungheechunggan-tang- (KCT-) 01, KCT-02, and Injinchunggan-tang (IJCGT) as newly developed decoctions containing 3–11 herbs in LPS-induced macrophages. KCT-01 showed the most potent inhibitory effects on LPS-induced NO, PGE2, TNF-α, and IL-6 production among those three herbal formulas. In addition, KCT-01 significantly inhibited LPS-induced iNOS and COX-2 at protein levels and expression of iNOS, COX-2, TNF-α, and IL-6 at mRNA levels. Molecular data revealed that KCT-01 attenuated the activation of JAK/STAT signaling cascade without affecting NF-κB or AP-1 activation. In ear inflammation induced by croton oil, KCT-01 significantly reduced edema, MPO activity, expression levels of iNOS and COX-2, and STAT3 phosphorylation in ear tissues. Taken together, our findings suggest that KCT-01 can downregulate the expression of proinflammatory genes by inhibiting JAK/STAT signaling pathway under inflammatory conditions. This study provides useful data for further exploration and application of KCT-01 as a potential anti-inflammatory medicine.

Effect of hypothyroidism on adenylyl cyclase activity and subtype gene expression in brown adipose tissue

1997 ◽  
Vol 273 (2) ◽  
pp. R762-R767 ◽  
Author(s):  
A. Chaudhry ◽  
J. G. Granneman
Keyword(s):  
Gene Expression ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Adenylyl Cyclase ◽  
Regulation Of Gene Expression ◽  
Mrna Levels ◽  
Adrenergic Stimulation ◽  
Functional Responses ◽  
Synergistic Interactions ◽  
Brown Adipose

Brown adipose tissue (BAT) expresses several adenylyl cyclase (AC) subtypes, and adrenergic stimulation selectively upregulates AC-III gene expression. Previous studies have described synergistic interactions between the sympathetic nervous system (SNS) and 3,5,3'-triiodothyronine (T3) on the regulation of gene expression in BAT. Because adrenergic stimulation also increases the activity of BAT type II thyroxine 5'-deiodinase (DII) and local T3 generation is important for many functional responses in BAT, we examined the effects of thyroid hormone status on the expression of various AC subtypes. Hypothyroidism selectively increased AC-III mRNA levels in BAT but not in white adipose tissue. Of the other subtypes examined, hypothyroidism did not alter AC-VI mRNA levels and slightly reduced AC-IX mRNA levels in BAT. The increase in AC-III expression was paralleled by an increase in forskolin-stimulated AC activity in BAT membranes. Sympathetic denervation of BAT abolished the increase in both AC activity and AC-III mRNA expression produced by hypothyroidism, but did not affect the expression of other subtypes. Surgical denervation also prevented the induction of AC-III in the cold-stressed euthyroid rat, but injections of T3 failed to alter AC-III expression in intact or denervated BAT. Our results indicate that T3 does not directly affect expression of AC-III. Rather, hypothyroidism increases BAT AC-III expression indirectly via an increase in sympathetic stimulation. Furthermore, our results strongly indicate that the increase in AC activity in hypothyroid BAT is due to increased expression of AC-III.

Modulation of gene expression in hibernating arctic ground squirrels

2008 ◽  
Vol 32 (2) ◽  
pp. 170-181 ◽  
Author(s):  
Jun Yan ◽  
Brian M. Barnes ◽  
Franziska Kohl ◽  
Thomas G. Marr
Keyword(s):  
Gene Expression ◽  
Circadian Rhythm ◽  
Cell Growth ◽  
Acid Metabolism ◽  
Molecular Transport ◽  
Ground Squirrels ◽  
Mrna Levels ◽  
Brown Adipose ◽  
Modulation Of Gene Expression ◽  
Arctic Ground Squirrels

We performed a broadscale screening of differential gene expression using both high-throughput bead-array technology and real-time PCR assay in brown adipose tissue, liver, heart, hypothalamus, and skeletal muscle in hibernating arctic ground squirrels, comparing animals sampled after two durations of steady-state torpor, during two stages of spontaneous arousal episodes, and in animals after they ended hibernation. Significant seasonal and torpor-arousal cycle differences of gene expression were detected in genes involved in glycolysis, fatty acid metabolism, gluconeogenesis, amino acid metabolism, molecular transport, detoxification, cardiac contractility, circadian rhythm, cell growth and apoptosis, muscle dystrophy, and RNA and protein protection. We observed, for the first time, complex modulation of gene expression during multiple stages of torpor-arousal cycles. The mRNA levels of certain metabolic genes drop significantly during the transition from late torpor to early arousal, perhaps due to the rapid turnover of mRNA transcripts resulting from the translational demands during thermogenesis in early arousal, whereas the mRNA levels of genes related to circadian rhythm, cell growth, and apoptosis rise significantly in the early or late arousal phases during torpor-arousal cycle, suggesting the resumption of circadian rhythm and cell cycle during arousal.

Synergistic Up-Regulation of Heme Oxygenase-1 in Human Liver by Heme and siRNA to Bach1:Possible Therapeutic Implications.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1633-1633
Author(s):  
Tahereh Ghaziani ◽  
Ying Shan ◽  
Richard W. Lambrecht ◽  
Herbert L. Bonkovsky
Keyword(s):  
Gene Expression ◽  
Heme Oxygenase ◽  
Ischemia Reperfusion Injury ◽  
Tissue Injury ◽  
Ischemia Reperfusion ◽  
Negative Regulator ◽  
Heme Oxygenase 1 ◽  
Significant Finding ◽  
Mrna Levels ◽  
Protein Levels

Abstract Background: Heme oxygenase-1 (HO-1) is an antioxidant defense enzyme that converts toxic heme into antioxidants. HO-1 is strongly up-regulated by its physiologic substrate, heme, which is currently the treatment of choice for acute attacks of porphyria and which may have other therapeutic uses, as well (e.g., for cytoprotection or amelioration of ischemia/reperfusion injury by increasing supply of carbon monoxide, biliverdin, or bilirubin). Up-regulation of HO-1 expression has been associated with increased resistance to tissue injury. Bach1 is a bZip protein which forms heterodimers with small Maf proteins. HO-1 is expressed at higher levels in tissues of Bach1-deficient mice, indicating that Bach1 acts as a negative regulator of the mouse HO-1 gene. The molecular mechanism that confers repression of HO-1 by Bach1, and whether there are similar effects in human cells, has remained elusive. The aim of this study was to assess whether modulation of human hepatic Bach1 expression by siRNA technology influences HO-1 gene expression and whether such gene silencing would enhance the inducing effects of heme on HO-1. Methods: siRNAs targeted 4 different positions of human Bach1 mRNA were designed and synthesized. We transfected Bach1-siRNA (25–200 nM) into Huh-7 cells using Lipofectamine for 24–72 h, after which, cells were treated with or without heme. We quantified HO-1 and Bach1 mRNA and protein levels by quantitative RT-PCR and western blotting, respectively. Effects and specificity of Bach1-siRNA were analyzed and compared with those of non-Bach1 related siRNAs (non-specific control-duplex (NSCD) and LaminB2-siRNA). Results: Bach1-siRNAs (25–200 nM) transfected into Huh-7 cells for 24–72 h significantly reduced Bach1 mRNA and protein levels approximately 80%, compared with non siRNA treated cells. In contrast, transfection with same amounts of NSCD or LaminB2 siRNA did not reduce Bach1 mRNA or protein levels, confirming the specificity of Bach1-siRNA in Huh-7 cells. A significant finding of these studies was the 7-fold up-regulation of the HO-1 gene in Bach1-siRNA transfected cells, compared to cells without Bach1-siRNA or those transfected with NSCD or LaminB2. Bach1, NSCD, and LaminB2 siRNAs had no effect on HO-2 or 5-aminolevulinate synthase-1 mRNA levels (two genes that are not induced by heme). The effects of increasing concentrations of heme (up to 10 μM) in the presence or absence of Bach1-siRNA on the levels of HO-1 mRNA expression are shown in the Figure. For all of the heme concentrations tested, the levels of HO-1 mRNA were greater when Bach1 siRNA was present. Conclusions: Bach1 has a specific and selective effect to repress expression of human hepatic HO-1. Silencing of the Bach1 gene by siRNAs may be a useful method for up-regulating HO-1 gene expression. The combination of intravenous heme and Bach1 silencing may be useful for therapy of acute porphyrias in relapse or other conditions in which up-regulation of HO-1 may be beneficial. (Supported by grants from NIH [DK38825] and Ovation Pharmaceuticals, Inc.) Figure Figure

Upregulation of the Anti-Apoptotic Protein, Survivin, in Hematopoietic Cells in Sickle Cell Anemia and Effects of Hydroxyurea Therapy.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1532-1532
Author(s):  
Carolina Lanaro ◽  
Carla Fernanda Franco-Penteado ◽  
Mariana R. B. Mello ◽  
Kleber Yotsumoto Fertrin ◽  
Marcos André C Bezerra ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Expression ◽  
Sickle Cell Anemia ◽  
Survivin Expression ◽  
Erythroid Differentiation ◽  
Mrna Levels ◽  
Gene Expressions ◽  
Protein Levels ◽  
Survivin Protein ◽  
Inflammatory State

Abstract Abstract 1532 Poster Board I-555 Survivin (BIRC5) is a member of the inhibitors of apoptosis family implicated in both prevention of cell death and control of mitosis. Although the actions of survivin in control of cancer cell division and apoptosis have been studied, its role in nonneoplastic diseases is not elucidated. Chronic inflammation is associated with STAT-3 upregulation, which can induce survivin production. Sickle cell anemia (SCA) has been characterized as a chronic inflammatory state and growing evidence indicates that inflammatory stress within the microvasculature may play a significant role in the vasoocclusion that is characteristic of SCA. Long-term treatment with hydroxyurea (HU) has been shown to reduce the production of inflammatory cytokines in SCA patients and leukocyte number. Since enhanced survivin expression has been reported in leukocytes under inflammatory conditions, and during hematopoietic cell survival and proliferation, the aim of this study was to investigate changes in survivin levels during erythroid differentiation, and determine expression in neutrophils (NS), mononuclear cells (MC) and red blood cell (RBC) in steady-state SCA patients (n≥10), SCA patients on HU therapy (n≥16), and healthy controls (HC, n≥5). Survivin and STAT-3 gene expression were determined by qRT-PCR analysis in primary human erythroblasts cultures for 7, 10 and 13 days and leukocytes separated from peripheral blood samples. Survivin protein expression was determined by flow cytometry with survivin-specific antibodies. Survivin gene expression was significantly increased during erythroid differentiation, but survivin mRNA levels showed similar patterns between SCA and HC (7d: 0.8±0.1 × 0.7±0.08; 10d: 1.7±0.3 × 1.6±0.2; 13d: 2.2± 0.27 × 1.8±0.19,U.A.,P>0.05,respectively). However, protein levels of survivin in mature RBC (glicophorin A +) was significantly higher in SCA patients compared to HC (41.90± 2.9 × 25.76±1.9, P=0.0006, respectively). BIRC-5 gene expression in MC was significantly higher in SCA patients compared to HC (0.9±0.1 × 0.5±0.2, P=0.04, respectively). Survivin protein levels in MC from SCA was significantly increased to compared to HC (51.7±3.2 × 39.7±1.7, MFI, P=0.01,respectively). Survivin protein levels are elevated in NS of SCA patients compared to HC (28.4±1.6 × 21.9±1.5, MFI, P=0.02,respectively). No significant alterations in the mRNA levels of the gene encoding STAT-3 were found during erythroid differentiation (7d: 1.1±0.04 × 1.1±0.08; 10d: 0.6±0.07 × 0.8±0.08; 13d: 0.6±0.07 × 0.9±0.1, P>0.05,respectively) or MC cells (1.2±0.1 × 1.1± 0.1, P>0.05,respectively) in SCA patients compared to HC. Patients on HU therapy demonstrated lower survivin MC gene expressions and protein levels compared to non-treated patients (0.6±0.3 × 0.9±0.1; 37.9±1.5 × 51.7±3.3, P=0.02; P<0.0001,respectively), but no difference was shown in STAT-3 gene expressions (1.1±0.04 × 1.2 ±0.1, respectively). Survivin protein levels were not significantly different in NS and RBC in patients on HU therapy compared to SCA (27.1±1.8 × 28.4± 1.6; 45.9± 3.2× 41.9± 2.9, MFI, P>0.05, respectively). Our data showed that survivin gene and protein expression are upregulated in MC in SCA patients, independently of STAT-3 expression. In addition, a high protein expression was observed in NS and RBC in these patients. HU therapy was associated with lower survivin expression in MC, but not NS and RBC, indicating that the beneficial effect that HU has on the inflammatory state, may participate in the reduced levels of survivin. In conclusion, the exact importance of survivin in SCA vasooclusion is not clear, but data indicates a high expression of this protein in leukocytes and RBC of SCA patients and may imply a role for this protein in leukocytosis and RBC proliferation in SCA. Disclosures No relevant conflicts of interest to declare.

scholarly journals Treatment with PPARαAgonist Clofibrate Inhibits the Transcription and Activation of SREBPs and Reduces Triglyceride and Cholesterol Levels in Liver of Broiler Chickens

PPAR Research ◽  
2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Lijun Zhang ◽  
Chunyan Li ◽  
Fang Wang ◽  
Shenghua Zhou ◽  
Mingjun Shangguan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Broiler Chickens ◽  
Target Genes ◽  
Nuclear Protein ◽  
Mrna Level ◽  
Control Group ◽  
Mrna Levels ◽  
Protein Levels ◽  
Cholesterol Levels ◽  
Regulation Mechanisms

PPARαagonist clofibrate reduces cholesterol and fatty acid concentrations in rodent liver by an inhibition of SREBP-dependent gene expression. In present study we investigated the regulation mechanisms of the triglyceride- and cholesterol-lowering effect of the PPARαagonist clofibrate in broiler chickens. We observed that PPARαagonist clofibrate decreases the mRNA and protein levels of LXRαand the mRNA and both precursor and nuclear protein levels of SREBP1 and SREBP2 as well as the mRNA levels of the SREBP1 (FASNandGPAM) and SREBP2 (HMGCRandLDLR) target genes in the liver of treated broiler chickens compared to control group, whereas the mRNA level ofINSIG2, which inhibits SREBP activation, was increased in the liver of treated broiler chickens compared to control group. Taken together, the effects of PPARαagonist clofibrate on lipid metabolism in liver of broiler chickens involve inhibiting transcription and activation of SREBPs and SREBP-dependent lipogenic and cholesterologenic gene expression, thereby resulting in a reduction of the triglyceride and cholesterol levels in liver of broiler chickens.

scholarly journals Postnatal selective suppression of lipoprotein lipase gene expression in brown adipose tissue (relative to the expression of the gene for the uncoupling protein) is not due to adrenergic insensitivity: a possible specific inhibitory effect of colostrum

1996 ◽  
Vol 314 (1) ◽  
pp. 261-267 ◽  
Author(s):  
María-Jesus OBREGÓN ◽  
Barbara CANNON ◽  
Jan NEDERGAARD
Keyword(s):  
Gene Expression ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Uncoupling Protein ◽  
Mrna Levels ◽  
Selective Suppression ◽  
Brown Adipose ◽  
Adrenergic Antagonist ◽  
Lpl Gene

The levels of mRNA coding for the uncoupling protein (UCP) and for lipoprotein lipase (LPL) were monitored in the brown adipose tissue of newborn rat pups. At 5 h after birth, the mRNA levels of UCP and LPL were high in pups exposed singly to 28 °C and low in pups kept singly at thermoneutrality (36 °C); in pups staying with the dam, the UCP mRNA levels were intermediate. However, the LPL mRNA levels were lower in pups staying with the dam than in pups at 36 °C, implying that factors additional to environmental temperature influenced LPL gene expression. Injection of noradrenaline into pups at thermoneutrality (36 °C) led to increases in UCP and LPL gene expression, but noradrenaline injections had no further effect in cold-exposed pups. The adrenergic effects were mediated via β-adrenergic receptors. The cold-induced increases in both UCP and LPL gene expression were abolished by the β-adrenergic antagonist propranolol. Thus differences in adrenergic responsiveness could not explain the differential expression of the UCP and LPL genes observed in pups staying with the dam. The presence of a physiological suppressor was examined by feeding single pups at 28 °C with different foods: nothing, water, Intralipid, cow's milk, rat milk and rat colostrum. None of these agents led to suppression of UCP gene expression, but colostrum led to a selective suppression of LPL gene expression. It was concluded that the genes for UCP and LPL were responsive to adrenergic stimuli immediately after birth, and it is suggested that a component of rat colostrum can selectively suppress LPL gene expression.

scholarly journals TcpH Influences Virulence Gene Expression in Vibrio cholerae by Inhibiting Degradation of the Transcription Activator TcpP

2004 ◽  
Vol 186 (24) ◽  
pp. 8309-8316 ◽  
Author(s):  
Nancy A. Beck ◽  
Eric S. Krukonis ◽  
Victor J. DiRita
Keyword(s):  
Gene Expression ◽  
Vibrio Cholerae ◽  
Time Course ◽  
Virulence Gene ◽  
Degradation Pathway ◽  
Mrna Levels ◽  
Transcription Activator ◽  
Virulence Gene Expression ◽  
Protein Levels ◽  
Periplasmic Domain

ABSTRACT Expression of toxT, the transcription activator of cholera toxin and pilus production in Vibrio cholerae, is the consequence of a complex cascade of regulatory events that culminates in activation of the toxT promoter by TcpP and ToxR, two membrane-localized transcription factors. Both are encoded in operons with genes whose products, TcpH and ToxS, which are also membrane localized, are hypothesized to control their activity. In this study we analyzed the role of TcpH in controlling TcpP function. We show that a mutant of V. cholerae lacking TcpH expressed virtually undetectable levels of TcpP, although tcpP mRNA levels remain unaffected. A time course experiment showed that levels of TcpP, expressed from a plasmid, are dramatically reduced over time without co-overexpression of TcpH. By contrast, deletion of toxS did not affect ToxR protein levels. A fusion protein in which the TcpP periplasmic domain is replaced with that of ToxR remains stable, suggesting that the periplasmic domain of TcpP is the target for degradation of the protein. Placement of the periplasmic domain of TcpP on ToxR, an otherwise stable protein, results in instability, providing further evidence for the hypothesis that the periplasmic domain of TcpP is a target for degradation. Consistent with this interpretation is our finding that derivatives of TcpP lacking a periplasmic domain are more stable in V. cholerae than are derivatives in which the periplasmic domain has been truncated. This work identifies at least one role for the periplasmic domain of TcpP, i.e., to act as a target for a protein degradation pathway that regulates TcpP levels. It also provides a rationale for why the V. cholerae tcpH mutant strain is avirulent. We hypothesize that regulator degradation may be an important mechanism for regulating virulence gene expression in V. cholerae.

Regulation of UCP1 and UCP3 in arctic ground squirrels and relation with mitochondrial proton leak

2006 ◽  
Vol 101 (1) ◽  
pp. 339-347 ◽  
Author(s):  
Jamie L. Barger ◽  
Brian M. Barnes ◽  
Bert B. Boyer
Keyword(s):  
Skeletal Muscle ◽  
Ground Squirrels ◽  
Proton Leak ◽  
Mrna Levels ◽  
Nonesterified Fatty Acids ◽  
Protein Levels ◽  
Bat Mitochondria ◽  
Brown Adipose ◽  
Arctic Ground Squirrels ◽  
Ucp3 Expression

Uncoupling protein (UCP) 1 (UCP1) catalyzes a proton leak in brown adipose tissue (BAT) mitochondria that results in nonshivering thermogenesis (NST), but the extent to which UCP homologs mediate NST in other tissues is controversial. To clarify the role of UCP3 in mediating NST in a hibernating species, we measured Ucp3 expression in skeletal muscle of arctic ground squirrels in one of three activity states (not hibernating, not hibernating and fasted for 48 h, or hibernating) and housed at 5°C or −10°C. We then compared Ucp3 mRNA levels in skeletal muscle with Ucp1 mRNA and UCP1 protein levels in BAT in the same animals. Ucp1 mRNA and UCP1 protein levels were increased on cold exposure and decreased with fasting, with the highest UCP1 levels in thermogenic hibernators. In contrast, Ucp3 mRNA levels were not affected by temperature but were increased 10-fold during fasting and >3-fold during hibernation. UCP3 protein levels were increased nearly fivefold in skeletal muscle mitochondria isolated from fasted squirrels compared with nonhibernators, but proton leak kinetics in the presence of BSA were unchanged. Proton leak in BAT mitochondria also did not differ between fed and fasted animals but did show classical inhibition by the purine nucleotide GDP. Levels of nonesterified fatty acids were highest during hibernation, and tissue temperatures during hibernation were related to Ucp1, but not Ucp3, expression. Taken together, these results do not support a role for UCP3 as a physiologically relevant mediator of NST in muscle.

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