scholarly journals Hypoxia-Induced ROS Promotes Mitochondrial Fission and Cisplatin Chemosensitivity via HIF-1α/Mff Regulation

2020 ◽  
Author(s):  
Kun Wu ◽  
Yuan-yuan Mao ◽  
Qi Chen ◽  
Bolin Zhang ◽  
Sheng Zhang ◽  
...  
Keyword(s):  
Malignant Tumors ◽  
Mitochondrial Dynamics ◽  
Dynamic Balance ◽  
Mitochondrial Fission ◽  
Hypoxia Inducible Factor ◽  
Hypoxic Condition ◽  
Clinical Samples ◽  
Hypoxic Conditions

Chemotherapy treatment based on Cisplatin (CDDP) is established as the drug of choice for head and neck squamous cell carcinoma (HNSCC). Malignant tumors respond to microenvironment alteration through a dynamic balance of mitochondrial fission and fusion. HNSCC is known to have hypoxic conditions, yet the effects and underlying mechanisms of hypoxia on chemosensitivity and mitochondrial dynamics remain unclear. We found that hypoxia promoted mitochondrial fission and CDDP sensitivity in HNSCC cells. Importantly, Mff was shown to be correlated with chemosensitivity in clinical samples of HNSCC that underwent a hypoxic condition. Hypoxia-inducible factor 1 α-subunit (HIF-1α) dramatically increased Mff transcriptional expression and directly bound to Mff. Hypoxia enhanced the release of reactive oxygen species (ROS) and upregulated the expression of Mff via HIF-1α in HNSCC cells. ROS depletion in HNSCC cells attenuated HIF-1α, Mff expression, and mitochondrial fission. Moreover, a knockdown of Mff suppressed hypoxia-induced mitochondrial fission and decreased CDDP chemosensitivity in vivo and in vitro. Our findings revealed that the hypoxia-induced release of ROS promoted mitochondrial fission and CDDP chemosensitivity via the regulation of HIF-1α/Mff in HNSCC cells, indicating that Mff may serve as a new biomarker to predict neoadjuvant chemosensitivity in HNSCC patients

scholarly journals Hypoxia-Induced ROS Promotes Mitochondrial Fission and Cisplatin Chemosensitivity via HIF-1α/Mff Regulation

2020 ◽  
Author(s):  
Kun Wu ◽  
Yuan-yuan Mao ◽  
Qi Chen ◽  
Bolin Zhang ◽  
Sheng Zhang ◽  
...  
Keyword(s):  
Malignant Tumors ◽  
Mitochondrial Dynamics ◽  
Dynamic Balance ◽  
Mitochondrial Fission ◽  
Hypoxia Inducible Factor ◽  
Hypoxic Condition ◽  
Clinical Samples ◽  
Α Subunit ◽  
Hypoxic Conditions ◽  
Underlying Mechanisms

Abstract BackgroundChemotherapy treatment based on Cisplatin (CDDP) is established as the drug of choice for head and neck squamous cell carcinoma (HNSCC). Malignant tumors respond to microenvironment alteration through a dynamic balance of mitochondrial fission and fusion. HNSCC is known to have hypoxic conditions, yet the effects and underlying mechanisms of hypoxia on chemosensitivity and mitochondrial dynamics remain unclear. ResultsWe found that hypoxia promoted mitochondrial fission and CDDP sensitivity in HNSCC cells. Importantly, Mff was shown to be correlated with chemosensitivity in clinical samples of HNSCC that underwent a hypoxic condition. Hypoxia-inducible factor 1 α-subunit (HIF-1α) dramatically increased Mff transcriptional expression and directly bound to Mff. Hypoxia enhanced the release of reactive oxygen species (ROS) and upregulated the expression of Mff via HIF-1α in HNSCC cells. ROS depletion in HNSCC cells attenuated HIF-1α, Mff expression, and mitochondrial fission. Moreover, a knockdown of Mff suppressed hypoxia-induced mitochondrial fission and decreased CDDP chemosensitivity in vivo and in vitro. ConclusionsOur findings revealed that the hypoxia-induced release of ROS promoted mitochondrial fission and CDDP chemosensitivity via the regulation of HIF-1α/Mff in HNSCC cells, indicating that Mff may serve as a new biomarker to predict neoadjuvant chemosensitivity in HNSCC patients.

scholarly journals Non-alcoholic fatty liver disease in mice with hepatocyte-specific deletion of mitochondrial fission factor

Diabetologia ◽  
2021 ◽  
Author(s):  
Yukina Takeichi ◽  
Takashi Miyazawa ◽  
Shohei Sakamoto ◽  
Yuki Hanada ◽  
Lixiang Wang ◽  
...  
Keyword(s):  
Er Stress ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Primary Hepatocytes ◽  
Alcoholic Fatty Liver ◽  
Expression Of Genes ◽  
Specific Deletion

Abstract Aims/hypothesis Mitochondria are highly dynamic organelles continuously undergoing fission and fusion, referred to as mitochondrial dynamics, to adapt to nutritional demands. Evidence suggests that impaired mitochondrial dynamics leads to metabolic abnormalities such as non-alcoholic steatohepatitis (NASH) phenotypes. However, how mitochondrial dynamics are involved in the development of NASH is poorly understood. This study aimed to elucidate the role of mitochondrial fission factor (MFF) in the development of NASH. Methods We created mice with hepatocyte-specific deletion of MFF (MffLiKO). MffLiKO mice fed normal chow diet (NCD) or high-fat diet (HFD) were evaluated for metabolic variables and their livers were examined by histological analysis. To elucidate the mechanism of development of NASH, we examined the expression of genes related to endoplasmic reticulum (ER) stress and lipid metabolism, and the secretion of triacylglycerol (TG) using the liver and primary hepatocytes isolated from MffLiKO and control mice. Results MffLiKO mice showed aberrant mitochondrial morphologies with no obvious NASH phenotypes during NCD, while they developed full-blown NASH phenotypes in response to HFD. Expression of genes related to ER stress was markedly upregulated in the liver from MffLiKO mice. In addition, expression of genes related to hepatic TG secretion was downregulated, with reduced hepatic TG secretion in MffLiKO mice in vivo and in primary cultures of MFF-deficient hepatocytes in vitro. Furthermore, thapsigargin-induced ER stress suppressed TG secretion in primary hepatocytes isolated from control mice. Conclusions/interpretation We demonstrated that ablation of MFF in liver provoked ER stress and reduced hepatic TG secretion in vivo and in vitro. Moreover, MffLiKO mice were more susceptible to HFD-induced NASH phenotype than control mice, partly because of ER stress-induced apoptosis of hepatocytes and suppression of TG secretion from hepatocytes. This study provides evidence for the role of mitochondrial fission in the development of NASH. Graphical abstract

Activating transcription factor 2 increases transactivation and protein stability of hypoxia-inducible factor 1α in hepatocytes

2009 ◽  
Vol 424 (2) ◽  
pp. 285-296 ◽  
Author(s):  
Jeong Hae Choi ◽  
Hyun Kook Cho ◽  
Yung Hyun Choi ◽  
JaeHun Cheong
Keyword(s):  
Transcription Factor ◽  
Protein Stability ◽  
Gene Transcription ◽  
Hypoxia Inducible Factor ◽  
Protein Stabilization ◽  
Hypoxic Conditions ◽  
Tumour Suppressor Protein ◽  
Activating Transcription Factor

HIF-1 (hypoxia inducible factor 1) performs a crucial role in mediating the response to hypoxia. However, other transcription factors are also capable of regulating hypoxia-induced target-gene transcription. In a previous report, we demonstrated that the transcription factor ATF-2 (activating transcription factor 2) regulates hypoxia-induced gene transcription, along with HIF-1α. In the present study, we show that the protein stability of ATF-2 is induced by hypoxia and the hypoxia-mimic CoCl2 (cobalt chloride), and that ATF-2 induction enhances HIF-1α protein stability via direct protein interaction. The knockdown of ATF-2 using small interfering RNA and translation-inhibition experiments demonstrated that ATF-2 plays a key role in the maintenance of the expression level and transcriptional activity of HIF-1α. Furthermore, we determined that ATF-2 interacts directly with HIF-1α both in vivo and in vitro and competes with the tumour suppressor protein p53 for HIF-1α binding. Collectively, these results show that protein stabilization of ATF-2 under hypoxic conditions is required for the induction of the protein stability and transactivation activity of HIF-1α for efficient hypoxia-associated gene expression.

scholarly journals PIM Kinases Alter Mitochondrial Dynamics and Chemosensitivity in Lung Cancer

2019 ◽  
Author(s):  
Shailender S. Chauhan ◽  
Rachel K. Toth ◽  
Corbin C. Jensen ◽  
Andrea L. Casillas ◽  
David F. Kashatus ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Mitochondrial Dynamics ◽  
Nsclc Patient ◽  
Mitochondrial Fission ◽  
Inverse Correlation ◽  
Mitochondrial Superoxide ◽  
Pim Kinases ◽  
Response To Chemotherapy

AbstractResistance to chemotherapy represents a major obstacle to the successful treatment of non-small cell lung cancer (NSCLC). The goal of this study was to determine how PIM kinases impact mitochondrial dynamics, ROS production, and response to chemotherapy in lung cancer. Live cell imaging and microscopy were used to determine the effect of PIM loss or inhibition on mitochondrial phenotype and ROS. Inhibition of PIM kinases caused excessive mitochondrial fission and significant upregulation of mitochondrial superoxide, increasing intercellular ROS. Mechanistically, we define a signaling axis linking PIM1 to Drp1 and mitochondrial fission in lung cancer. PIM inhibition significantly increased the protein levels and mitochondrial localization of Drp1, causing marked fragmentation of mitochondria. An inverse correlation between PIM1 and Drp1 was confirmed in NSCLC patient samples. Inhibition of PIM sensitized NSCLC to chemotherapy and produced a synergistic anti-tumor response in vitro and in vivo. Immunohistochemistry and transmission electron microscopy verified that PIM inhibitors promote mitochondrial fission and apoptosis in vivo. These data improve our knowledge about how PIM1 regulates mitochondria and provide justification for combining PIM inhibition with chemotherapy in NSCLC.

scholarly journals Repeated hypoglycemia blunts the responsiveness of glucose-inhibited GHRH neurons by remodeling neural inputs and disrupting mitochondrial structure and function

2019 ◽  
Author(s):  
M Bayne ◽  
A Alvarsson ◽  
K Devarakonda ◽  
R Li ◽  
M Jimenez-Gonzalez ◽  
...  
Keyword(s):  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Glucose Deprivation ◽  
Glucose Sensing ◽  
Diabetic Patients ◽  
Hypoglycemia Unawareness ◽  
Atp Production ◽  
Low Glucose

AbstractHypoglycemia is a frequent complication of diabetes, limiting therapy and increasing morbidity and mortality. With recurrent hypoglycemia, the counter-regulatory response (CRR) to decreased blood glucose is blunted, resulting in hypoglycemia unawareness. The mechanisms leading to these blunted effects remain incompletely understood. Here, we identify, with in situ hybridization, immunohistochemistry and the tissue clearing capability of iDisco, that GHRH neurons represent a unique population of arcuate nucleus neurons activated by glucose deprivation in vivo. Repeated glucose deprivation reduces GHRH neuron activation and remodels excitatory and inhibitory inputs to GHRH neurons. We show low glucose sensing is coupled to GHRH neuron depolarization, decreased ATP production and mitochondrial fusion. Repeated hypoglycemia attenuates these responses during low glucose. By maintaining mitochondrial length with the small molecule, mdivi-1, we preserved hypoglycemia sensitivity in vitro and in vivo. Our findings present possible mechanisms for the blunting of the CRR, broaden significantly our understanding of the structure of GHRH neurons and for the fist time, propose that mitochondrial dynamics play an important role in hypoglycemia unawareness. We conclude that interventions targeting mitochondrial fission in GHRH neurons may offer a new pathway to prevent hypoglycemia unawareness in diabetic patients.

Monoclonal Antibody-Based Screening Assay for Factor Inhibiting Hypoxia-Inducible Factor Inhibitors

2008 ◽  
Vol 13 (6) ◽  
pp. 494-503 ◽  
Author(s):  
Sang-Hyeup Lee ◽  
Jeong Hee Moon ◽  
Eun Ah Cho ◽  
Seong-Eon Ryu ◽  
Myung Kyu Lee
Keyword(s):  
Monoclonal Antibody ◽  
High Throughput Screening ◽  
Transcriptional Activity ◽  
Hypoxia Inducible Factor ◽  
Enzyme Linked Immunosorbent Assay ◽  
Sensitive Assay ◽  
Screening Assay ◽  
Hypoxic Conditions

The factor-inhibiting hypoxia-inducible factor (FIH) hydroxylates the asparagine 803 (Asn803) residue of the hypoxia-inducible factor 1α (HIF-1α), and the modification abrogates the transcriptional activity of HIF-1α. Because FIH is more active on HIF-1α than prolyl hydroxylase domain proteins under hypoxic conditions, its inhibitors have potential to be developed as anti-ischemic drugs targeting normal cells stressed by hypoxia. In this study, the authors developed the first monoclonal antibody, SHN-HIF1α, specifically to Asn803 hydroxylated HIF-1α and a sensitive assay system for FIH inhibitors using the monoclonal antibody (Mab). SHN-HIF1α showed 740 times higher affinity to the Asn803 hydroxylated HIF-1α peptide than the unmodified one. An enzyme-linked immunosorbent assay—based system using SHN-HIF1α displayed at least 30 times more sensitivity than previous methods for screening FIH inhibitors and was easily applicable to develop a high-throughput screening system. SHN-HIF1α also showed an Asn803 hydroxylation-dependent specificity to HIF-1α in cells. Taken together, the results suggest that it may be used to analyze the in vivo and in vitro activities of FIH inhibitors. ( Journal of Biomolecular Screening 2008:494-503)

scholarly journals The Phosphatase SHP-2 Activates HIF-1α in Wounds In Vivo by Inhibition of 26S Proteasome Activity

2019 ◽  
Vol 20 (18) ◽  
pp. 4404 ◽  
Author(s):  
Yvonn Heun ◽  
Katharina Grundler Groterhorst ◽  
Kristin Pogoda ◽  
Bjoern F Kraemer ◽  
Alexander Pfeifer ◽  
...  
Keyword(s):  
Tyrosine Phosphatase ◽  
Hypoxia Inducible Factor ◽  
Proteasome Activity ◽  
26S Proteasome ◽  
Mitogen Activated Protein Kinase ◽  
Hypoxic Conditions ◽  
Mitogen Activated Protein ◽  
Specific Regulation

Vascular remodeling and angiogenesis are required to improve the perfusion of ischemic tissues. The hypoxic environment, induced by ischemia, is a potent stimulus for hypoxia inducible factor 1α (HIF-1α) upregulation and activation, which induce pro-angiogenic gene expression. We previously showed that the tyrosine phosphatase SHP-2 drives hypoxia mediated HIF-1α upregulation via inhibition of the proteasomal pathway, resulting in revascularization of wounds in vivo. However, it is still unknown if SHP-2 mediates HIF-1α upregulation by affecting 26S proteasome activity and how the proteasome is regulated upon hypoxia. Using a reporter construct containing the oxygen-dependent degradation (ODD) domain of HIF-1α and a fluorogenic proteasome substrate in combination with SHP-2 mutant constructs, we show that SHP-2 inhibits the 26S proteasome activity in endothelial cells under hypoxic conditions in vitro via Src kinase/p38 mitogen-activated protein kinase (MAPK) signalling. Moreover, the simultaneous expression of constitutively active SHP-2 (E76A) and inactive SHP-2 (CS) in separate hypoxic wounds in the mice dorsal skin fold chamber by localized magnetic nanoparticle-assisted lentiviral transduction showed specific regulation of proteasome activity in vivo. Thus, we identified a new additional mechanism of SHP-2 mediated HIF-1α upregulation and proteasome activity, being functionally important for revascularization of wounds in vivo. SHP-2 may therefore constitute a potential novel therapeutic target for the induction of angiogenesis in ischemic vascular disease.

Transcriptional regulation mechanisms of hypoxia-induced neuroglobin gene expression

2012 ◽  
Vol 443 (1) ◽  
pp. 153-164 ◽  
Author(s):  
Ning Liu ◽  
Zhanyang Yu ◽  
Shuanglin Xiang ◽  
Song Zhao ◽  
Anna Tjärnlund-Wolf ◽  
...  
Keyword(s):  
Gene Expression ◽  
Hypoxia Inducible Factor ◽  
Gene Promoter ◽  
Nuclear Factor Κb ◽  
Proximal Promoter ◽  
Mobility Shift ◽  
Hypoxic Conditions ◽  
Mobility Shift Assay

Ngb (neuroglobin) has been identified as a novel endogenous neuroprotectant. However, little is known about the regulatory mechanisms of Ngb expression, especially under conditions of hypoxia. In the present study, we located the core proximal promoter of the mouse Ngb gene to a 554 bp segment, which harbours putative conserved NF-κB (nuclear factor κB)- and Egr1 (early growth-response factor 1) -binding sites. Overexpression and knockdown of transcription factors p65, p50, Egr1 or Sp1 (specificity protein 1) increased and decreased Ngb expression respectively. Experimental assessments with transfections of mutational Ngb gene promoter constructs, as well as EMSA (electrophoretic mobility-shift assay) and ChIP (chromatin immunoprecipitation) assays, demonstrated that NF-κB family members (p65, p50 and cRel), Egr1 and Sp1 bound in vitro and in vivo to the proximal promoter region of the Ngb gene. Moreover, a κB3 site was found as a pivotal cis-element responsible for hypoxia-induced Ngb promoter activity. NF-κB (p65) and Sp1 were also responsible for hypoxia-induced up-regulation of Ngb expression. Although there are no conserved HREs (hypoxia-response elements) in the promoter of the mouse Ngb gene, the results of the present study suggest that HIF-1α (hypoxia-inducible factor-1α) is also involved in hypoxia-induced Ngb up-regulation. In conclusion, we have identified that NF-κB, Egr1 and Sp1 played important roles in the regulation of basal Ngb expression via specific interactions with the mouse Ngb promoter. NF-κB, Sp1 and HIF-1α contributed to the up-regulation of mouse Ngb gene expression under hypoxic conditions.

scholarly journals Preparation and Characterization of Hypoxia Sensitive Cationic Liposomal Doxorubicin and Evaluation Its Anti-tumor Activity in Mice Bearing C26 Tumors

2021 ◽  
Author(s):  
Mohammad Mashreghi ◽  
Mahdi Faal Maleki ◽  
Anis Askarizadeh ◽  
Helaleh Farshchi ◽  
Leila Farhoudi ◽  
...  
Keyword(s):  
Liposomal Doxorubicin ◽  
Pegylated Liposomal Doxorubicin ◽  
Tumor Model ◽  
Cationic Liposome ◽  
Cost Effective ◽  
Hypoxic Condition ◽  
Hypoxic Conditions ◽  
Cytotoxicity Studies

Abstract The goal of this study was to prepare cationic nanoliposomal doxorubicin in which PEG molecule attached to the liposome via a hypoxia-sensitive azo linker. The cost-effective hypoxia-sensitive molecule (HSM) was synthesized composing of C18H37 lipophilic tail, azo-linker, and PEG2000 hydrophilic molecule. The NMR and FTIR were employed to characterize the HSM. Then, this compound was post-inserted into the cationic liposome (Cat-lip), and PEG-Azo-Cat-lip was prepared and characterized using DLS. In vitro release and cytotoxicity studies were performed in normoxic and hypoxic conditions. In vivo biodistribution and anti-tumor activities of the formulations were studied on mice bearing C-26 colon carcinoma tumor model and compared with PEGylated liposomal doxorubicin (Caelyx®). Besides, the histological test confirmed the formulation biosafety on healthy mice. The results of NMR and FTIR indicated the synthesis of HSM. The decrease in the zeta-potential of formulation from +18.4 mV for Cat-lip to +6.1 mV along with the increase in the size of the PEG-Azo-Cat-lip indicated the successful post-insertion of HSM. The release study showed that PEGylation results in the more stable PEG-Azo-Cat-lip compared to the Cat-lip. The increased cytotoxicity of the PEG-Azo-Cat-lip in the hypoxic condition also indicated the cleavage of the azo-linker in the hypoxic environment. In vivo biodistribution using animal imaging has shown higher tumor accumulation of the PEG-Azo-Cat-lip than Cat-lip during the 120 h of the study. The results of anti-tumor activities and biosafety of the formulations also showed the higher efficiency of the PEG-Azo-Cat-lip compared with the Cat-lip. The results of this study, indicated the anti-tumor efficacy of this hypoxia-sensitive which merits further investigation.

scholarly journals UDCA Inhibits Hypoxic Hepatocellular Carcinoma Cell–Induced Angiogenesis Through Suppressing HIF-1α/VEGF/IL-8 Intercellular Signaling

2021 ◽  
Vol 12 ◽  
Author(s):  
Wanfu Lin ◽  
Shu Li ◽  
Yongbin Meng ◽  
Guokai Huang ◽  
Shufang Liang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Hypoxia Inducible Factor ◽  
Hypoxic Condition ◽  
Tube Formation ◽  
Luciferase Reporter ◽  
Enzyme Linked Immunosorbent Assay ◽  
Intercellular Signaling ◽  
Hcc Cells

Background: A hypoxic microenvironment may induce angiogenesis and promote the development of hepatocellular carcinoma (HCC). The aim of this study was to evaluate whether ursodeoxycholic acid (UDCA) may inhibit hypoxic HCC cell–induced angiogenesis and the possible mechanisms.Methods: Tube formation and matrigel plug angiogenesis assays were used to evaluate angiogenesis in vitro and in vivo, respectively. Real-time PCR, enzyme-linked immunosorbent assay, and Western blot were used to evaluate the mRNA and protein expressions of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and IL-8, respectively. Dual-luciferase reporter assay was applied to assess the reporter gene expression of hypoxia-response element (HRE).Results: UDCA antagonized hypoxic Huh 7 cell-induced tube formation of EA.hy 926 cells. In HCC cells, UDCA inhibited hypoxia-induced upregulation of VEGF and IL-8 both in mRNA and protein levels. UDCA also inhibited IL-8–induced angiogenesis in vitro and in vivo through suppressing IL-8–induced phosphorylation of ERK. The levels of HIF-1α mRNA and protein and HRE-driven luciferase activity in HCC cells were upregulated by hypoxia and were all inhibited by UDCA. The proteasome inhibitor MG132 antagonized the effect of UDCA on HIF-1α degradation. In hypoxic condition, the phosphorylation of ERK and AKT was obviously increased in HCC cells, which was suppressed by UDCA. Transfection of the HIF-1α overexpression plasmid reversed the effects of UDCA on hypoxic HCC cell–induced angiogenesis, HRE activity, and expressions of IL-8 and VEGF.Conclusions: Our results demonstrated that UDCA could inhibit hypoxic HCC cell–induced angiogenesis through suppressing HIF-1α/VEGF/IL-8–mediated intercellular signaling between HCC cells and endothelial cells.

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