scholarly journals SDHC Promoter Methylation, a Novel Pathogenic Mechanism in Parasympathetic Paragangliomas

2017 ◽  
Vol 103 (1) ◽  
pp. 295-305 ◽  
Author(s):  
Cristóbal Bernardo-Castiñeira ◽  
Nuria Valdés ◽  
Marta I Sierra ◽  
Inés Sáenz-de-Santa-María ◽  
Gustavo F Bayón ◽  
...  
Keyword(s):  
Copy Number ◽  
Messenger Rna ◽  
Hypoxia Inducible Factor ◽  
Mrna Levels ◽  
Cluster Assembly ◽  
Iron Sulfur Cluster ◽  
Genetic Event ◽  
Protein Levels ◽  
First Case ◽  
Vhl Protein

Abstract Context Germline mutations in the succinate dehydrogenase A, B, C, and D genes (collectively, SDHx) predispose to the development of paragangliomas (PGLs) arising at the parasympathetic or sympathetic neuroendocrine systems. SDHx mutations cause absence of tumoral immunostaining for SDHB. However, negative SDHB immunostaining has also been found in a subset of PGLs that lack SDHx mutations. Settings Here, we report the comprehensive molecular characterization of one such a tumor of parasympathetic origin compared with healthy paraganglia and other PGLs with or without SDHx mutations. Results Integration of multiplatform data revealed somatic SDHC methylation and loss of the 1q23.3 region containing the SDHC gene. This correlated with decreased SDHC messenger RNA (mRNA) and protein levels. Furthermore, another genetic event found affected the VHL gene, which showed a decreased DNA copy number, associated with low VHL mRNA levels, and an absence of VHL protein detected by immunohistochemistry. In addition, the tumor displayed a pseudohypoxic phenotype consisting in overexpression of the hypoxia-inducible factor (HIF)-1α and miR-210, as well as downregulation of the iron-sulfur cluster assembly enzyme (ISCU) involved in SDHB maturation. This profile resembles that of SDHx- or VHL-mutated PGLs but not of PGLs with decreased VHL copy number, pointing to SDHC rather than VHL as the pathogenic driver. Conclusions Collectively, these findings demonstrate the potential importance of both the SDHC epigenomic event and the activation of the HIF-1α/miR-210/ISCU axis in the pathogenesis of SDHx wild-type/SDHB-negative PGLs. To our knowledge, this is the first case of a sporadic parasympathetic PGL that carries silencing of SDHC, fulfilling the two-hit Knudson’s model for tumorigenesis.

scholarly journals IOP1, a novel hydrogenase-like protein that modulates hypoxia-inducible factor-1α activity

2006 ◽  
Vol 401 (1) ◽  
pp. 341-352 ◽  
Author(s):  
Jianhe Huang ◽  
Daisheng Song ◽  
Adrian Flores ◽  
Quan Zhao ◽  
Sharon M. Mooney ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Hypoxia Inducible Factor ◽  
Cell Types ◽  
Mrna Levels ◽  
Low Oxygen ◽  
Gene Expressions ◽  
Iron Sulfur Cluster ◽  
Α Subunit ◽  
Protein Levels ◽  
Hypoxic Conditions

A central means by which mammalian cells respond to low oxygen tension is through the activation of the transcription factor HIF-1 (hypoxia-inducible factor-1). Under normoxic conditions, HIF-1α (the α subunit of HIF-1) is targeted for rapid degradation by the ubiquitin–proteasome pathway. Under hypoxic conditions, this degradation is inhibited, thereby leading to the stabilization and activation of HIF-1α. Here, we report the identification of IOP1 (iron-only hydrogenase-like protein 1), a protein homologous with enzymes present in anaerobic organisms that contain a distinctive iron–sulfur cluster. IOP1 is present in a broad range of cell types. Knockdown of IOP1 using siRNA (small interfering RNA) in mammalian cells increases protein levels of HIF-1α under both normoxic and hypoxic conditions, and augments hypoxia-induced HRE (hypoxia response element) reporter gene and endogenous HIF-1α target gene expressions. We find that IOP1 knockdown up-regulates HIF-1α mRNA levels, thereby providing a mechanism by which knockdown induces the observed effects. The results collectively provide evidence that IOP1 is a component of the protein network that regulates HIF-1α in mammalian cells.

scholarly journals Endotoxin-induced tissue factor messenger RNA in human monocytes is negatively regulated by a cyclic AMP-dependent mechanism

Blood ◽  
1993 ◽  
Vol 81 (4) ◽  
pp. 973-979 ◽  
Author(s):  
V Ollivier ◽  
S Houssaye ◽  
C Ternisien ◽  
A Leon ◽  
H de Verneuil ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Tissue Factor ◽  
Messenger Rna ◽  
Factor Viia ◽  
Functional Expression ◽  
Mrna Levels ◽  
Proteolytic Activation ◽  
Protein Levels ◽  
Tf Gene ◽  
Camp Levels

Abstract Tissue factor (TF) is a transmembrane receptor that serves as the major cofactor for factor VIIa-catalyzed proteolytic activation of factors IX and X. In response to bacterial lipopolysaccharide (LPS), monocytes transcribe, synthesize, and express TF on their surface, thereby conveying to activated monocytes the ability to initiate the blood coagulation protease cascades. Agents that elevate cellular cyclic AMP (cAMP) inhibit the functional expression of TF by LPS-stimulated monocytes. In this study, we investigated the mechanism of this suppression. Northern blot analysis of total RNA from LPS-stimulated monocytes showed a concentration-dependent decrease in TF messenger RNA (mRNA) levels in response to dibutyryl-cAMP (dBt-cAMP). TF mRNA and procoagulant activity were inhibited as early as 1 hour after the addition of dBt-cAMP and the inhibition persisted through 4 hours. Suppression of specific mRNA abundance was also observed with agents, including forskolin and iso-butyl-methyl-xanthine (IBMX), that increase cAMP levels by independent mechanisms. Flow immunocytometric analysis confirmed that cell-surface TF protein levels declined in parallel with TF functional activity. The rate of decay of TF mRNA after the arrest of transcription by actinomycin D was not altered by the addition of dBt-cAMP, IBMX, or forskolin, thus excluding effects on TF mRNA stability. We conclude that elevated cAMP levels suppress TF mRNA by reducing the rate of TF gene transcription.

scholarly journals Effects of Diabetes and Insulin on α-amylase Messenger RNA Levels in Rat Parotid Glands

1990 ◽  
Vol 69 (8) ◽  
pp. 1500-1504 ◽  
Author(s):  
S.K. Kim ◽  
L.M. Cuzzort ◽  
R.K. McKean ◽  
E.D. Allen
Keyword(s):  
Parotid Gland ◽  
Beta Cell ◽  
Messenger Rna ◽  
Secretory Protein ◽  
Diabetic Rats ◽  
Mrna Levels ◽  
Mrna Synthesis ◽  
Parotid Glands ◽  
Protein Levels ◽  
Rat Parotid

Previous studies have shown that amylase levels are reduced significantly in the pancreas and parotid gland of diabetic rats and that insulin reverses this effect and increases the secretory protein levels. In the pancreas, these changes in amylase protein levels are accompanied by parallel changes in amylase mRNA levels. In the present study, the effects of diabetes and subsequent insulin treatments on contents ( per cell) of amylase protein and its mRNA in parotid glands were compared in rats rendered diabetic with an injection of a beta-cell toxin, streptozotocin (STZ). Both amylase protein and its mRNA contents were reduced significantly in diabetic rats, compared with control rats, and this reduction was reversed following insulin injections of diabetic rats. In insulin-injected diabetic rats, amylase protein contents increased before a detectable increase in amylase mRNA levels was seen. The mRNA contents of a non-secretory protein, actin, did not change during diabetogenesis or subsequent insulin treatments. The reductions in parotid contents of amylase and its mRNA in diabetic rats and the reversal of these changes by insulin are similar to those changes that occur in the pancreas under the same conditions. However, the magnitude of these changes in parotid glands was much smaller than in the pancreas, and the effect of insulin on amylase mRNA synthesis was not as immediate as in the latter gland.

scholarly journals VHL inhibitor binding increases intracellular level of VHL

2021 ◽  
Author(s):  
Julianty Frost ◽  
Sonia Rocha ◽  
Alessio Ciulli
Keyword(s):  
Enzyme Inhibitor ◽  
Hypoxia Inducible Factor ◽  
High Specificity ◽  
Protein Levels ◽  
Tumour Suppressor Protein ◽  
Functional Characterisation ◽  
Vhl Protein ◽  
Factor Alpha ◽  
Vhl Disease ◽  
Protein Stabilisation

The vonHippel Lindau (VHL) protein is a tumour suppressor protein frequently mutated in the VHL disease, which functions as substrate recognition subunit of a Cul2 E3 ubiquitin ligase (CRL2VHL). CRL2VHL plays an important role in oxygen sensing, by binding and targeting Hypoxia Inducible Factor-alpha subunits (HIF-alpha) for ubiquitination and degradation. VHL is also commonly hijacked by heterobifunctional degrader molecules known as proteolysis-targeting chimeras (PROTACs). In previous work we reported the structure-based design and functional characterisation of VHL inhibitors (VH032 and VH298) that induce the HIF response in cells. Here, we use unbiased quantitative mass spectrometry to identify the proteomic changes elicited by the VHL inhibitor and compare this to hypoxia or broad-spectrum prolyl-hydroxylase domain (PHD) enzyme inhibitor IOX2. Our results demonstrate the VHL inhibitor selectively activates the HIF response that vastly overlaps with hypoxia- and IOX2-induced proteomic changes. Interestingly, VHL inhibitors were found to selectively upregulate a single protein, which is VHL itself. Our analysis revealed that this occurs via protein stabilisation of VHL isoforms and not via changes in transcript levels. Increased VHL levels upon VH298 treatment resulted in turn to reduced levels of HIF-1 protein. Our results demonstrate the high specificity of VHL inhibitors and suggest that use of these inhibitors would not produce overtly side effects due to prolonged HIF stabilisation. They also exemplify the concept that small-molecule binding induced protein stabilisation can increase protein levels inside cells.

scholarly journals A comparative study on the effects of high-fat diet and endurance training on the PGC-1α-FNDC5/irisin pathway in obese and nonobese male C57BL/6 mice

2018 ◽  
Vol 43 (7) ◽  
pp. 651-662 ◽  
Author(s):  
Fatemeh Kazeminasab ◽  
Sayed Mohammad Marandi ◽  
Kamran Ghaedi ◽  
Zahra Safaeinejad ◽  
Fahimeh Esfarjani ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Endurance Training ◽  
Messenger Rna ◽  
Muscle Protein ◽  
Exercise Session ◽  
Mrna Levels ◽  
Skeletal Muscle Protein ◽  
High Fat ◽  
Low Fat ◽  
Protein Levels

The present study was performed to clarify how a combined exercise/diet treatment could affect the expression level of the muscle fibronectin type III domain containing 5 (Fndc5) with respect to body fat mass. Male C57BL/6 mice were divided into 2 groups including low-fat (LF) and high-fat (HF) diets for 12 weeks. Then, LF fed (nonobese) and HF fed mice (obese) were divided into the following 4 groups: HF-Exercise, HF-Sedentary, LF-Exercise, and LF-Sedentary. The exercise group exercised on a motor-driven treadmill for 45 min/day, 5 days/week for 8 weeks. Mice were sacrificed 24 h after the final exercise session. Gastrocnemius muscle and the visceral adipose tissue were excised and frozen for the assessment of proliferator-activated receptor gamma coactivator 1 alpha (Pgc-1α) and Fndc5 messenger RNA (mRNA) and protein levels. Data indicated that protein level of muscle PGC-1α was decreased in HF versus LF groups and in obese versus nonobese mice. Moreover, Fndc5 mRNA levels were increased in the muscle tissue of HF versus LF groups and in obese versus nonobese mice. Also, in the gastrocnemius skeletal muscle, protein levels of FNDC5 were significantly higher in the HF fed mice, as compared with their low-fat fed counterparts, similar to what was observed for exercised versus sedentary mice. Overall, we found that the HF diet increased Fndc5 transcript levels in the skeletal muscle, but exercise had a minimal effect on the transcript level of Fndc5, whereas endurance training increased the protein content of FNDC5 in the skeletal muscle.

scholarly journals Intrauterine Exposure to Cadmium Reduces HIF-1 DNA-Binding Ability in Rat Fetal Kidneys

Toxics ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 53 ◽  
Author(s):  
Tania Jacobo-Estrada ◽  
Mariana Cardenas-Gonzalez ◽  
Mitzi Santoyo-Sánchez ◽  
Frank Thevenod ◽  
Olivier Barbier
Keyword(s):  
Dna Binding ◽  
Kidney Development ◽  
Protein Extraction ◽  
Hypoxia Inducible Factor ◽  
Isotonic Saline ◽  
Mrna Levels ◽  
Vegf Mrna ◽  
Binding Ability ◽  
Protein Levels ◽  
Cd Exposure

During embryonic development, some hypoxia occurs due to incipient vascularization. Under hypoxic conditions, gene expression is mainly controlled by hypoxia-inducible factor 1 (HIF-1). The activity of this transcription factor can be altered by the exposure to a variety of compounds; among them is cadmium (Cd), a nephrotoxic heavy metal capable of crossing the placenta and reaching fetal kidneys. The goal of the study was to determine Cd effects on HIF-1 on embryonic kidneys. Pregnant Wistar rats were exposed to a mist of isotonic saline solution or CdCl2 (DDel = 1.48 mg Cd/kg/day), from gestational day (GD) 8 to 20. Embryonic kidneys were obtained on GD 21 for RNA and protein extraction. Results show that Cd exposure had no effect on HIF-1α and prolyl hydroxylase 2 protein levels, but it reduced HIF-1 DNA-binding ability, which was confirmed by a decrease in vascular endothelial growth factor (VEGF) mRNA levels. In contrast, the protein levels of VEGF were not changed, which suggests the activation of additional regulatory mechanisms of VEGF protein expression to ensure proper kidney development. In conclusion, Cd exposure decreases HIF-1-binding activity, posing a risk on renal fetal development.

scholarly journals Oxygen regulation of the epithelial Na channel in the collecting duct

2011 ◽  
Vol 300 (2) ◽  
pp. F412-F424 ◽  
Author(s):  
Russell F. Husted ◽  
Hongyan Lu ◽  
Rita D. Sigmund ◽  
John B. Stokes
Keyword(s):  
Kinase Activity ◽  
Collecting Duct ◽  
Hypoxia Inducible Factor ◽  
Na Channel ◽  
Mrna Levels ◽  
Apical Surface ◽  
Amp Kinase ◽  
Na Transport ◽  
Protein Levels ◽  
Epithelial Na Channel

The Po2 within the kidney changes dramatically from cortex to medulla. The present experiments examined the effect of changing Po2 on epithelial Na channel (ENaC)-mediated Na transport in the collecting duct using the mpkCCD-c14 cell line. Decreasing ambient O2 concentration from 20 to 8% decreased ENaC activity by 40%; increasing O2 content to 40% increased ENaC activity by 50%. The O2 effect required several hours to develop and was not mimicked by the acid pH that developed in monolayers incubated in low-O2 medium. Corticosteroids increased ENaC activity at each O2 concentration; there was no interaction. The pathways for O2 and steroid regulation of ENaC are different since O2 did not substantially affect Sgk1, α-ENaC, Gilz, or Usp2–45 mRNA levels, genes involved in steroid-mediated ENaC regulation. The regulation of ENaC activity by these levels of O2 appears not to be mediated by changes in hypoxia-inducible factor-1α or -2α activity or a change in AMP kinase activity. Changes in O2 concentration had minimal effect on α- or γ-ENaC mRNA and protein levels; there were moderate effects on β-ENaC levels. However, 40% O2 induced substantially greater total β- and γ-ENaC on the apical surface compared with 8% O2; both subunits demonstrated a greater increase in the mature forms. The α-ENaC subunit was difficult to detect on the apical surface, perhaps because our antibodies do not recognize the major mature form. These results identify a mechanism of ENaC regulation that may be important in different regions of the kidney and in responses to changes in dietary NaCl.

scholarly journals Inhibitory Effect of the Noncamptothecin Topoisomerase I Inhibitor LMP-400 on Female Mice Models and Human Pheochromocytoma Cells

Endocrinology ◽  
2015 ◽  
Vol 156 (11) ◽  
pp. 4094-4104 ◽  
Author(s):  
Jan Schovanek ◽  
Petra Bullova ◽  
Yasin Tayem ◽  
Alessio Giubellino ◽  
Robert Wesley ◽  
...  
Keyword(s):  
Topoisomerase I ◽  
Hypoxia Inducible Factor ◽  
Human Tumor ◽  
Inhibitory Effect ◽  
Mrna Levels ◽  
Topoisomerase I Inhibitor ◽  
Female Mice ◽  
Topoisomerase 1 ◽  
Protein Levels

Metastatic pheochromocytoma continues to be an incurable disease, and treatment with conventional cytotoxic chemotherapy offers limited efficacy. In the present study, we evaluated a novel topoisomerase I inhibitor, LMP-400, as a potential treatment for this devastating disease. We found a high expression of topoisomerase I in human metastatic pheochromocytoma, providing a basis for the evaluation of a topoisomerase 1 inhibitor as a therapeutic strategy. LMP-400 inhibited the cell growth of established mouse pheochromocytoma cell lines and primary human tumor tissue cultures. In a study performed in athymic female mice, LMP-400 demonstrated a significant inhibitory effect on tumor growth with two drug administration regimens. Furthermore, low doses of LMP-400 decreased the protein levels of hypoxia-inducible factor 1 (HIF-1α), one of a family of factors studied as potential metastatic drivers in these tumors. The HIF-1α decrease resulted in changes in the mRNA levels of HIF-1 transcriptional targets. In vitro, LMP-400 showed an increase in the growth-inhibitory effects in combination with other chemotherapeutic drugs that are currently used for the treatment of pheochromocytoma. We conclude that LMP-400 has promising antitumor activity in preclinical models of metastatic pheochromocytoma and its use should be considered in future clinical trials.

Increased expression of HIF-1α, nNOS, and VEGF in the cerebral cortex of anemic rats

2007 ◽  
Vol 292 (1) ◽  
pp. R403-R414 ◽  
Author(s):  
Anya T. McLaren ◽  
Philip A. Marsden ◽  
C. David Mazer ◽  
Andrew J. Baker ◽  
Duncan J. Stewart ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Hypoxia Inducible Factor ◽  
Hemoglobin Concentration ◽  
Mrna Levels ◽  
Cortical Cells ◽  
Neuronal Marker ◽  
Protein Levels ◽  
Axonal Projections ◽  
Endothelial Growth Factor ◽  
Vegf Protein

This study tested the hypothesis that specific hypoxic molecules, including hypoxia-inducible factor-1α (HIF-1α), neuronal nitric oxide synthase (nNOS), and vascular endothelial growth factor (VEGF), are upregulated within the cerebral cortex of acutely anemic rats. Isoflurane-anesthetized rats underwent acute hemodilution by exchanging 50% of their blood volume with pentastarch. Following hemodilution, mean arterial pressure and arterial PaO2 values did not differ between control and anemic rats while the hemoglobin concentration decreased to 57 ± 2 g/l. In anemic rats, cerebral cortical HIF-1α protein levels were increased, relative to controls (1.7 ± 0.5-fold, P < 0.05). This increase was associated with an increase in mRNA levels for VEGF, erythropoietin, CXCR4, iNOS, and nNOS ( P < 0.05 for all), but not endothelial NOS. Cerebral cortical nNOS and VEGF protein levels were increased in anemic rats, relative to controls (2.0 ± 0.2- and 1.5 ± 0.4-fold, respectively, P < 0.05 for both). Immunohistochemistry demonstrated increased HIF-1α and VEGF staining in perivascular regions of the anemic cerebral cortex and an increase in the number of nNOS-positive cerebral cortical cells (3.2 ± 1.0-fold, P < 0.001). The nNOS-positive cells costained with the neuronal marker, Neu-N, but not with the astrocytic marker glial fibrillary acidic protein (GFAP). These nNOS-positive neurons frequently sent axonal projections toward cerebral blood vessels. Conversely, VEGF immunostaining colocalized with both neuronal (NeuN) and astrocytic markers (GFAP). In conclusion, acute normotensive, normoxemic hemodilution increased the levels of HIF-1α protein and mRNA for HIF-1-responsive molecules. nNOS and VEGF protein levels were also increased within the cerebral cortex of anemic rats at clinically relevant hemoglobin concentrations.

scholarly journals RSUME is implicated in HIF-1-induced VEGF-A production in pituitary tumour cells

2011 ◽  
Vol 19 (1) ◽  
pp. 13-27 ◽  
Author(s):  
B Shan ◽  
J Gerez ◽  
M Haedo ◽  
M Fuertes ◽  
M Theodoropoulou ◽  
...  
Keyword(s):  
Pituitary Adenoma ◽  
Hypoxia Inducible Factor ◽  
Pituitary Tumour ◽  
Mrna Levels ◽  
Human Pituitary ◽  
Human Pituitary Adenoma ◽  
Protein Levels ◽  
Hypoxic Conditions ◽  
Adaptive Processes ◽  
Endothelial Growth Factor

The recently cloned small RWD-domain containing protein RSUME was shown to increase protein levels of hypoxia-inducible factor-1α (HIF-1α). The latter is the oxygen-regulated subunit of HIF-1, the most important transcription factor of the cellular adaptive processes to hypoxic conditions. It is also a major regulator of vascular endothelial growth factor-A (VEGF-A), which is critically involved in the complex process of tumour neovascularisation. In this study, the expression and role of RSUME in pituitary tumours was studied. We found that RSUME mRNA was up-regulated in pituitary adenomas and significantly correlated with HIF-1α mRNA levels. Hypoxia (1% O2) or treatment with hypoxia-mimicking CoCl2enhanced RSUME and HIF-1α expression, induced translocation of HIF-1α to the nuclei and stimulated VEGF-A production both in pituitary tumour cell lines and primary human pituitary adenoma cell cultures. When RSUME expression was specifically down-regulated by siRNA, the CoCl2-induced increase VEGF-A secretion was strongly reduced which was shown to be a consequence of the RSUME knockdown-associated reduction of HIF-1α synthesis. Thus, RSUME plays an important role in initiating pituitary tumour neovascularisation through regulating HIF-1α levels and subsequent VEGF-A production and may therefore be critically involved in pituitary adenoma progression.

Sign in / Sign up

Export Citation Format

Share Document