scholarly journals Expression of HIF-1α and VEGF in Skeletal Muscle of Plateau Animals in Response to Hypoxic Stress

2014 ◽  
pp. 801-805
Author(s):  
H.-C. XIE ◽  
J.-P. HE ◽  
J.-F. ZHU ◽  
J.-G. LI
Keyword(s):  
Skeletal Muscle ◽  
Skeletal Muscles ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Hypoxic Stress ◽  
Sprague Dawley ◽  
Protein Levels ◽  
Sd Rats ◽  
Hypoxic Environment ◽  
Endothelial Growth Factor

Hypoxia-inducible factor-1α (HIF-1α) transcriptionally regulates expression of several target genes in protecting tissues against hypoxia. With hypoxic stress, vascular endothelial growth factor (VEGF) is a signal protein produced by cells and further contributes to improvement of vascular functions and restoring the oxygen supply to tissues. In this current study, we first hypothesized that the protein levels of HIF-1α and VEGF are reduced in skeletal muscles of plateau animals [China Qinghai-Tibetan plateau pikas (ochotona curzoniae)] in response to hypoxia as compared with control animals [normal lowland Sprague-Dawley (SD) rats]. We further hypothesized that HIF-1α plays a role in regulating expression of VEGF in skeletal muscle. Note that HIF-1α and VEGF were determined by using two-site immunoenzymatic assay (ELISA) methods. Our results demonstrated that hypoxic stress induced by exposure of lower O2 (6 h) significantly increased the levels of HIF-1α and VEGF in the oxidative and glycolytic muscles of SD rats and pikas (P<0.05 vs. normoxic conditions). Notably, the increases in HIF-1α and VEGF were significantly less in pikas (P<0.05, vs. SD controls) than in SD rats. In addition, a linear relationship was observed between amplified HIF-1α and VEGF in oxidative muscle (r=0.76 and P<0.01) and glycolytic muscle (r=0.72 and P<0.01) and inhibiting HIF-1α significantly decreased expression of VEGF induced by hypoxic stress in skeletal muscles (P<0.05). Overall, our findings suggest that (1) responsiveness of HIF-1α and VEGF in skeletal muscles to hypoxic stress is blunted in plateau animals, and (2) HIF-1α has a regulatory effect on VEGF under hypoxic environment.

scholarly journals Differential Responsiveness in VEGF Receptor Subtypes to Hypoxic Stress in Various Tissues of Plateau Animals

2017 ◽  
pp. 357-362 ◽  
Author(s):  
H.-C. XIE ◽  
J.-G. LI ◽  
J.-P. HE
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Hypoxia Inducible Factor ◽  
Receptor Subtypes ◽  
Vegf Receptor ◽  
Hypoxic Stress ◽  
Adaptive Responses ◽  
Sprague Dawley ◽  
Low Oxygen ◽  
Hypoxic Environment

With hypoxic stress, hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) are elevated and their responses are altered in skeletal muscles of plateau animals [China Qinghai-Tibetan plateau pikas (Ochotona curzoniae)] as compared with control animals [normal lowland Sprague-Dawley (SD) rats]. The results indicate that HIF-1α and VEGF are engaged in physiological functions under hypoxic environment. The purpose of the current study was to examine the protein levels of VEGF receptor subtypes (VEGFRs: VEGFR-1, VEGFR-2 and VEGFR-3) in the end organs, namely skeletal muscle, heart and lung in response to hypoxic stress. ELISA and Western blot analysis were employed to determine HIF-1α and the protein expression of VEGFRs in control animals and plateau pikas. We further blocked HIF-1α signal to determine if HIF-1α regulates alternations in VEGFRs in those tissues. We hypothesized that responsiveness of VEGFRs in the major end organs of plateau animals is differential with insult of hypoxic stress and is modulated by low oxygen sensitive HIF-1α. Our results show that hypoxic stress induced by exposure of lower O2 for 6 h significantly increased the levels of VEGFR-2 in skeletal muscle, heart and lung and the increases were amplified in plateau pikas. Our results also demonstrate that hypoxic stress enhanced VEGFR-3 in lungs of plateau animals. Nonetheless, no significant alternations in VEGFR-1 were observed in those tissues with hypoxic stress. Moreover, we observed decreases of VEGFR-2 in skeletal muscle, heart and lung; and decreases of VEGFR-3 in lung following HIF-1α inhibition. Overall, our findings suggest that in plateau animals 1) responsiveness of VEGFRs is different under hypoxic environment; 2) amplified VEGFR-2 response appears in skeletal muscle, heart and lung, and enhanced VEGFR-3 response is mainly observed in lung; 3) HIF-1α plays a regulatory role in the levels of VEGFRs. Our results provide the underlying cellular and molecular mechanisms responsible for hypoxic environment in plateau animals, having an impact on research of physiological and ecological adaptive responses to acute or chronic hypoxic stress in humans who living at high attitude and who live at a normal sea level but suffer from hypoxic disorders.

scholarly journals PHD3 Acts as Tumor Suppressor in Mouse Osteosarcoma and Influences Tumor Vascularization via PDGF-C Signaling

Cancers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 496
Author(s):  
Antje Egners ◽  
Maryam Rezaei ◽  
Aleksandar Kuzmanov ◽  
David Poitz ◽  
Doreen Streichert ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Tumor Progression ◽  
Target Genes ◽  
Tumor Tissue ◽  
Hypoxia Inducible Factor ◽  
Cancer Cell Proliferation ◽  
Downstream Signaling ◽  
Protein Levels ◽  
Hypoxic Environment ◽  
Transcriptional Complex

Cancer cell proliferation and insufficient blood supply can lead to the development of hypoxic areas in the tumor tissue. The adaptation to the hypoxic environment is mediated by a transcriptional complex called hypoxia-inducible factor (HIF). HIF protein levels are tightly controlled by oxygen-dependent prolyl hydroxylase domain proteins (PHDs). However, the precise roles of these enzymes in tumor progression and their downstream signaling pathways are not fully characterized. Here, we study PHD3 function in murine experimental osteosarcoma. Unexpectedly, PHD3 silencing in LM8 cells affects neither HIF-1α protein levels, nor the expression of various HIF-1 target genes. Subcutaneous injection of PHD3-silenced tumor cells accelerated tumor progression and was accompanied by dramatic phenotypic changes in the tumor vasculature. Blood vessels in advanced PHD3-silenced tumors were enlarged whereas their density was greatly reduced. Examination of the molecular pathways underlying these alterations revealed that platelet-derived growth factor (PDGF)-C signaling is activated in the vasculature of PHD3-deficient tumors. Silencing of PDGF-C depleted tumor growth, increased vessel density and reduced vessel size. Our data show that PHD3 controls tumor growth and vessel architecture in LM8 osteosarcoma by regulating the PDGF-C pathway, and support the hypothesis that different members of the PHD family exert unique functions in tumors.

Differential expression of Flk-1 and Flt-1 in rat skeletal muscle in response to chronic ischaemia: favourable effect of muscle activity

2003 ◽  
Vol 105 (4) ◽  
pp. 473-482 ◽  
Author(s):  
Malgorzata MILKIEWICZ ◽  
Olga HUDLICKA ◽  
Julie VERHAEG ◽  
Stuart EGGINTON ◽  
Margaret D. BROWN
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Favourable Effect ◽  
Sprague Dawley ◽  
Artery Ligation ◽  
Protein Levels ◽  
Capillary Growth ◽  
Sprague Dawley Rats ◽  
Endothelial Growth Factor ◽  
Vegf Protein

To determine the involvement of vascular endothelial growth factor (VEGF) and its receptors Flk-1 and Flt-1 in capillary growth in ischaemic skeletal muscle, extensor digitorum longus muscles from hindlimbs of Sprague—Dawley rats were studied at 1, 2 and 5 week intervals after iliac artery ligation. Muscle VEGF protein levels (as determined by Western-blot analysis) increased only after 2 (60%) and 5 (80%) weeks, with more capillaries positively immunostained for VEGF than in control muscles. Ischaemia-induced angiogenesis was gradual, with capillary proliferation at 1 and 2 weeks and capillary:fibre ratio increased 20% after 5 weeks. This was associated with an initial doubling of Flk-1 protein after 1 week that declined below control levels by 5 weeks, whereas Flt-1 expression was elevated more than 40% at all time points. During more sustained ischaemia (femoral ligation 3 weeks after iliac ligation), VEGF protein level at 5 weeks was even higher, but Flt-1 and Flk-1 were unchanged from control levels and no capillary growth occurred. Intermittent electrical stimulation (10 Hz, 7×15 min/day) of these ischaemic muscles between weeks 3–5 did not elevate VEGF further, but increased Flk-1 by 32%, decreased Flt-1 by 71%, and led to significant capillary growth. These results demonstrate that during chronic muscle ischaemia Flk-1 and Flt-1 are regulated differentially and that electrical stimulation of ischaemic muscles can promote angiogenesis via Flk-1 up-regulation. Even when ischaemic muscle VEGF levels are high, capillary growth appears to be dependent on the presence of Flk-1.

Effect of microgravity on the expression of mitochondrial enzymes in rat cardiac and skeletal muscles

1998 ◽  
Vol 84 (2) ◽  
pp. 593-598 ◽  
Author(s):  
Michael K. Connor ◽  
David A. Hood
Keyword(s):  
Skeletal Muscle ◽  
Enzyme Activity ◽  
Skeletal Muscles ◽  
Male Rats ◽  
Mitochondrial Enzymes ◽  
Mrna Levels ◽  
Triceps Brachii ◽  
Protein Levels ◽  
Functional Consequences ◽  
Microgravity Conditions

Connor, Michael K., and David A. Hood. Effect of microgravity on the expression of mitochondrial enzymes in rat cardiac and skeletal muscles. J. Appl. Physiol. 84(2): 593–598, 1998.—The purpose of this study was to examine the expression of nuclear and mitochondrial genes in cardiac and skeletal muscle (triceps brachii) in response to short-duration microgravity exposure. Six adult male rats were exposed to microgravity for 6 days and were compared with six ground-based control animals. We observed a significant 32% increase in heart malate dehydrogenase (MDH) enzyme activity, which was accompanied by a 62% elevation in heart MDH mRNA levels after microgravity exposure. Despite modest elevations in the mRNAs encoding subunits III, IV, and VIc as well as a 2.2-fold higher subunit IV protein content after exposure to microgravity, heart cytochrome c oxidase (CytOx) enzyme activity remained unchanged. In skeletal muscle, MDH expression was unaffected by microgravity, but CytOx activity was significantly reduced 41% by microgravity, whereas subunit III, IV, and VIc mRNA levels and subunit IV protein levels were unaltered. Thus tissue-specific (i.e., heart vs. skeletal muscle) differences exist in the regulation of nuclear-encoded mitochondrial proteins in response to microgravity. In addition, the expression of nuclear-encoded proteins such as CytOx subunit IV and expression of MDH are differentially regulated within a tissue. Our data also illustrate that the heart undergoes previously unidentified mitochondrial adaptations in response to short-term microgravity conditions more dramatic than those evident in skeletal muscle. Further studies evaluating the functional consequences of these adaptations in the heart, as well as those designed to measure protein turnover, are warranted in response to microgravity.

Protective effect of hydralazine on a cellular model of Parkinson’s disease: a possible role of hypoxia-inducible factor (HIF)-1α

2020 ◽  
Vol 98 (3) ◽  
pp. 405-414 ◽  
Author(s):  
Mehrnaz Mehrabani ◽  
Mohammad Hadi Nematollahi ◽  
Mojde Esmaeili Tarzi ◽  
Kobra Bahrampour Juybari ◽  
Moslem Abolhassani ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Antioxidant Power ◽  
Expression Levels ◽  
Downstream Target ◽  
Protein Levels ◽  
Ferric Reducing Antioxidant Power ◽  
6 Hydroxydopamine

Parkinson’s disease (PD) is a neurodegenerative disease accompanied by a low expression level of cerebral hypoxia-inducible factor (HIF-1α). Hence, activating the hypoxia-signaling pathway may be a favorable therapeutic approach for curing PD. This study explored the efficacy of hydralazine, a well-known antihypertensive agent, for restoring the impaired HIF-1 signaling in PD, with the aid of 6-hydroxydopamine (6-OHDA)-exposed SH-SY5Y cells. The cytotoxicity of hydralazine and 6-OHDA on the SH-SY5Y cells were evaluated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and apoptosis detection assays. The activities of malondialdehyde, nitric oxide (NO), ferric reducing antioxidant power (FRAP), and superoxide dismutase (SOD) were also measured. Expression levels of HIF-1α and its downstream genes at the protein level were assessed by Western blotting. Hydralazine showed no toxic effects on SH-SY5Y cells, at the concentration of ≤50 μmol/L. Hydralazine decreased the levels of apoptosis, malondialdehyde, and NO, and increased the activities of FRAP and SOD in cells exposed to 6-OHDA. Furthermore, hydralazine up-regulated the protein expression levels of HIF-1α, vascular endothelial growth factor, tyrosine hydroxylase, and dopamine transporter in the cells also exposed to 6-OHDA, by comparison with the cells exposed to 6-OHDA alone. In summary, hydralazine priming could attenuate the deleterious effects of 6-OHDA on SH-SY5Y cells by increasing cellular antioxidant capacity, as well as the protein levels of HIF-1α and its downstream target genes.

Hypoxia-Inducible Factor 1 in Lower Limb Ischemia

Vascular ◽  
2006 ◽  
Vol 14 (6) ◽  
pp. 321-327 ◽  
Author(s):  
Teik K. Ho ◽  
David J. Abraham ◽  
Carol M. Black ◽  
Daryll M. Baker
Keyword(s):  
Skeletal Muscle ◽  
Lower Limb ◽  
Target Genes ◽  
Therapeutic Potential ◽  
Hypoxia Inducible Factor ◽  
Limb Ischemia ◽  
Limb Amputation ◽  
Western World ◽  
High Morbidity ◽  
Activity Increase

In the Western world, peripheral vascular disease (PVD) has a high prevalence and is associated with high morbidity and mortality. More patients are presenting with critical limb ischemia (CLI), the end stage of PVD, because of an increased life expectancy owing to improved medical care. In a large percentage of these patients, lower limb amputation is still required, despite current advances in surgery and interventional radiology. Studies of ischemic skeletal muscles disclosed evidence of endogenous angiogenesis and adaptive skeletal muscle metabolic changes in response to hypoxia. Many of the genes responsible for these responses are regulated by hypoxia-inducible factor (HIF)-1. HIF-1, consisting of HIF-1α and HIF-1β subunits, is a major transcription factor that functions as a master regulator of oxygen homeostasis that plays essential roles in cellular and systemic pathophysiology. HIF-1α expression and HIF-1 transcriptional activity increase exponentially as cellular oxygen concentration is decreased. More than 60 target genes that are transactivated by HIF-1 have been identified. Many of the target genes, such as vascular endothelial growth factor, have been studied extensively, especially in tumors. However, only recently that interest in HIF-1 is growing in relation to ischemic diseases. Most of the studies concentrated mainly on the angiogenic property of HIF-1. In contrast, there is a lack of information on the role of HIF-1 in skeletal muscle metabolic adaptive changes as the end-organ in PVD. This review aims to summarize our current understanding of HIF-1 roles and the therapeutic potential in PVD.

scholarly journals Neuroprotection by Dimethyloxalylglycine following Permanent and Transient Focal Cerebral Ischemia in Rats

2010 ◽  
Vol 31 (1) ◽  
pp. 132-143 ◽  
Author(s):  
Simon Nagel ◽  
Michalis Papadakis ◽  
Ruoli Chen ◽  
Lisa C Hoyte ◽  
Keith J Brooks ◽  
...  
Keyword(s):  
Focal Cerebral Ischemia ◽  
Hypoxia Inducible Factor ◽  
Artery Occlusion ◽  
Protein Levels ◽  
Transient Focal Cerebral Ischemia ◽  
Before And After ◽  
Magnetic Resonance Imaging Mri ◽  
The Stability ◽  
Endothelial Growth Factor ◽  
Endothelial Nitric Oxide

Dimethyloxalylglycine (DMOG) is an inhibitor of prolyl-4-hydroxylase domain (PHD) enzymes that regulate the stability of hypoxia-inducible factor (HIF). We investigated the effect of DMOG on the outcome after permanent and transient middle cerebral artery occlusion (p/tMCAO) in the rat. Before and after pMCAO, rats were treated with 40 mg/kg, 200 mg/kg DMOG, or vehicle, and with 40 mg/kg or vehicle after tMCAO. Serial magnetic resonance imaging (MRI) was performed to assess infarct evolution and regional cerebral blood flow (rCBF). Both doses significantly reduced infarct volumes, but only 40 mg/kg improved the behavior after 24 hours of pMCAO. Animals receiving 40 mg/kg were more likely to maintain rCBF values above 30% from the contralateral hemisphere within 24 hours of pMCAO. DMOG after tMCAO significantly reduced the infarct volumes and improved behavior at 24 hours and 8 days and also improved the rCBF after 24 hours. A consistent and significant upregulation of both mRNA and protein levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) was associated with the observed neuroprotection, although this was not consistently related to HIF-1α levels at 24 hours and 8 days. Thus, DMOG afforded neuroprotection both at 24 hours after pMCAO and at 24 hours and 8 days after tMCAO. This effect was associated with an increase of VEGF and eNOS and was mediated by improved rCBF after DMOG treatment.

scholarly journals The chromatin remodeler ISWI regulates the cellular response to hypoxia: role of FIH

2011 ◽  
Vol 22 (21) ◽  
pp. 4171-4181 ◽  
Author(s):  
Andrew Melvin ◽  
Sharon Mudie ◽  
Sonia Rocha
Keyword(s):  
Rna Polymerase Ii ◽  
Chromatin Remodeling ◽  
Cellular Response ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Prolyl Hydroxylases ◽  
Additional Information ◽  
Protein Levels ◽  
Survival Factor

The hypoxia-inducible factor (HIF) is a master regulator of the cellular response to hypoxia. Its levels and activity are controlled by dioxygenases called prolyl-hydroxylases and factor inhibiting HIF (FIH). To activate genes, HIF has to access sequences in DNA that are integrated in chromatin. It is known that the chromatin-remodeling complex switch/sucrose nonfermentable (SWI/SNF) is essential for HIF activity. However, no additional information exists about the role of other chromatin-remodeling enzymes in hypoxia. Here we describe the role of imitation switch (ISWI) in the cellular response to hypoxia. We find that unlike SWI/SNF, ISWI depletion enhances HIF activity without altering its levels. Furthermore, ISWI knockdown only alters a subset of HIF target genes. Mechanistically, we find that ISWI is required for full expression of FIH mRNA and protein levels by changing RNA polymerase II loading to the FIH promoter. Of interest, exogenous FIH can rescue the ISWI-mediated upregulation of CA9 but not BNIP3, suggesting that FIH-independent mechanisms are also involved. Of importance, ISWI depletion alters the cellular response to hypoxia by reducing autophagy and increasing apoptosis. These results demonstrate a novel role for ISWI as a survival factor during the cellular response to hypoxia.

scholarly journals Suppression of Pyruvate Dehydrogenase Kinase by Dichloroacetate in Cancer and Skeletal Muscle Cells Is Isoform Specific and Partially Independent of HIF-1α

2021 ◽  
Vol 22 (16) ◽  
pp. 8610
Author(s):  
Nives Škorja Milić ◽  
Klemen Dolinar ◽  
Katarina Miš ◽  
Urška Matkovič ◽  
Maruša Bizjak ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cancer Cells ◽  
Pyruvate Dehydrogenase ◽  
Hypoxia Inducible Factor ◽  
Muscle Cells ◽  
Pyruvate Dehydrogenase Kinase ◽  
Skeletal Muscle Cells ◽  
Dependent Manner ◽  
Protein Levels ◽  
L6 Myotubes

Inhibition of pyruvate dehydrogenase kinase (PDK) emerged as a potential strategy for treatment of cancer and metabolic disorders. Dichloroacetate (DCA), a prototypical PDK inhibitor, reduces the abundance of some PDK isoenzymes. However, the underlying mechanisms are not fully characterized and may differ across cell types. We determined that DCA reduced the abundance of PDK1 in breast (MDA-MB-231) and prostate (PC-3) cancer cells, while it suppressed both PDK1 and PDK2 in skeletal muscle cells (L6 myotubes). The DCA-induced PDK1 suppression was partially dependent on hypoxia-inducible factor-1α (HIF-1α), a transcriptional regulator of PDK1, in cancer cells but not in L6 myotubes. However, the DCA-induced alterations in the mRNA and the protein levels of PDK1 and/or PDK2 did not always occur in parallel, implicating a role for post-transcriptional mechanisms. DCA did not inhibit the mTOR signaling, while inhibitors of the proteasome or gene silencing of mitochondrial proteases CLPP and AFG3L2 did not prevent the DCA-induced reduction of the PDK1 protein levels. Collectively, our results suggest that DCA reduces the abundance of PDK in an isoform-dependent manner via transcriptional and post-transcriptional mechanisms. Differential response of PDK isoenzymes to DCA might be important for its pharmacological effects in different types of cells.

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