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 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

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.

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 A novel role for kynurenine 3-monooxygenase in mitochondrial dynamics

PLoS Genetics ◽  
2020 ◽  
Vol 16 (11) ◽  
pp. e1009129
Author(s):  
Daniel C. Maddison ◽  
Mónica Alfonso-Núñez ◽  
Aisha M. Swaih ◽  
Carlo Breda ◽  
Susanna Campesan ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Translational Regulation ◽  
Metabolic Flux ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Kynurenine Pathway ◽  
Loss Of Function ◽  
Disease Associated Genes

The enzyme kynurenine 3-monooxygenase (KMO) operates at a critical branch-point in the kynurenine pathway (KP), the major route of tryptophan metabolism. As the KP has been implicated in the pathogenesis of several human diseases, KMO and other enzymes that control metabolic flux through the pathway are potential therapeutic targets for these disorders. While KMO is localized to the outer mitochondrial membrane in eukaryotic organisms, no mitochondrial role for KMO has been described. In this study, KMO deficient Drosophila melanogaster were investigated for mitochondrial phenotypes in vitro and in vivo. We find that a loss of function allele or RNAi knockdown of the Drosophila KMO ortholog (cinnabar) causes a range of morphological and functional alterations to mitochondria, which are independent of changes to levels of KP metabolites. Notably, cinnabar genetically interacts with the Parkinson’s disease associated genes Pink1 and parkin, as well as the mitochondrial fission gene Drp1, implicating KMO in mitochondrial dynamics and mitophagy, mechanisms which govern the maintenance of a healthy mitochondrial network. Overexpression of human KMO in mammalian cells finds that KMO plays a role in the post-translational regulation of DRP1. These findings reveal a novel mitochondrial role for KMO, independent from its enzymatic role in the kynurenine pathway.

scholarly journals Fis1 phosphorylation by Met promotes mitochondrial fission and hepatocellular carcinoma metastasis

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Yan Yu ◽  
Xiao-Dan Peng ◽  
Xiao-Jun Qian ◽  
Kai-Ming Zhang ◽  
Xiang Huang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Tyrosine Kinase ◽  
Receptor Tyrosine Kinase ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Critical Role ◽  
Structured Illumination ◽  
Structured Illumination Microscopy

AbstractMet tyrosine kinase, a receptor for a hepatocyte growth factor (HGF), plays a critical role in tumor growth, metastasis, and drug resistance. Mitochondria are highly dynamic and undergo fission and fusion to maintain a functional mitochondrial network. Dysregulated mitochondrial dynamics are responsible for the progression and metastasis of many cancers. Here, using structured illumination microscopy (SIM) and high spatial and temporal resolution live cell imaging, we identified mitochondrial trafficking of receptor tyrosine kinase Met. The contacts between activated Met kinase and mitochondria formed dramatically, and an intact HGF/Met axis was necessary for dysregulated mitochondrial fission and cancer cell movements. Mechanically, we found that Met directly phosphorylated outer mitochondrial membrane protein Fis1 at Tyr38 (Fis1 pY38). Fis1 pY38 promoted mitochondrial fission by recruiting the mitochondrial fission GTPase dynamin-related protein-1 (Drp1) to mitochondria. Fragmented mitochondria fueled actin filament remodeling and lamellipodia or invadopodia formation to facilitate cell metastasis in hepatocellular carcinoma (HCC) cells both in vitro and in vivo. These findings reveal a novel and noncanonical pathway of Met receptor tyrosine kinase in the regulation of mitochondrial activities, which may provide a therapeutic target for metastatic HCC.

Abstract 283: SGK1-Dependent Sirt3 Phosphorylation Regulates Mitochondrial Dynamics

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Dallas Ellis ◽  
Takara Scott ◽  
Wei Zhong ◽  
Oguljahan Babayeva ◽  
Sharon C Francis
Keyword(s):  
Molecular Mechanisms ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Ectopic Expression ◽  
Mitochondrial Fragmentation ◽  
Proteomic Screen ◽  
Protein Levels ◽  
Stimulation Of

Mitochondrial dynamics (i.e. fusion and fission) is impaired in models of obesity and can result in target organ dysfunction. However, the mechanisms that regulate mitochondrial dynamics in the setting of obesity are not completely understood. The objectives of this study are to examine a role for and determine the molecular mechanisms of serum and glucocorticoid-inducible kinase 1 (SGK1) in obesity-related mitochondrial dynamics in the vasculature. We recently reported that aortic expression of SGK1 is elevated in a model of diet-induced obesity (DIO) in vivo and by resistin; a fat-derived adipokine, in human aortic smooth muscle cells (SMC) in vitro . To directly examine the effects of SMC-derived SGK1 on mitochondrial dynamics, wildtype and SMC-specific SGK1 knockout mice were subjected to DIO for eight weeks. Our results indicate that SMC-specific deletion of SGK1 induced a fused, elongated mitochondrial phenotype in aortic SMC in vivo and attenuated obesity-mediated arterial mitochondrial fragmentation suggesting a role for SGK1 in stimulation of mitochondrial fission. To determine the molecular mechanism for this effect, we performed a proteomic screen for novel SGK1 substrates and identified the mitochondrial deacetylase SIRT3 as a novel SGK1 target. Mass spectrometry indicates SGK1 phosphorylates SIRT3 on serine103. Increasing doses of resistin augmented SIRT3-S103 phosphorylation and caused a concomitant decrease in total SIRT3 in rat aortic SMC in vitro . To examine whether SGK1-dependent SIRT3 phosphorylation regulates the mitochondrial fission protein machinery; we evaluated total and activated levels of Drp1, the mitochondrial fission regulator, in response to ectopic expression of SIRT3 wildtype, phospho-memetic (S103D) and phospho-deficient (S103A) mutants. SIRT3-S103D increased total Drp1 and activated Drp1 protein levels an effect inhibited by SIRT3-S103A. These findings implicate elevated resistin observed during obesity in stimulation of SGK1 and subsequent phosphorylation of SIRT3 leading to activation of Drp1 and stimulation of arterial mitochondrial fragmentation.

scholarly journals Mitochondrial Transplantation Modulates Inflammation and Apoptosis, Alleviating Tendinopathy Both In Vivo and In Vitro

Antioxidants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 696
Author(s):  
Ji Min Lee ◽  
Jung Wook Hwang ◽  
Mi Jin Kim ◽  
Sang Youn Jung ◽  
Kyung-Soo Kim ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Tendon Healing ◽  
Nuclear Factor Κb ◽  
Therapeutic Effects ◽  
Matrix Metalloproteinase 1 ◽  
Anti Inflammatory

Tendinopathy is a common musculoskeletal condition causing pain and dysfunction. Conventional treatment and surgical procedures for tendinopathy are insufficient; accordingly, recent research has focused on tendon-healing regenerative approaches. Tendon injuries usually occur in the hypoxic critical zone, characterized by increased oxidative stress and mitochondrial dysfunction; thus, exogenous intact mitochondria may be therapeutic. We aimed to assess whether mitochondrial transplantation could induce anti-inflammatory activity and modulate the metabolic state of a tendinopathy model. Exogenous mitochondria were successfully delivered into damaged tenocytes by centrifugation. Levels of Tenomodulin and Collagen I in damaged tenocytes were restored with reductions in nuclear factor-κB and matrix metalloproteinase 1. The dysregulation of oxidative stress and mitochondrial membrane potential was attenuated by mitochondrial transplantation. Activated mitochondrial fission markers, such as fission 1 and dynamin-related protein 1, were dose-dependently downregulated. Apoptosis signaling pathway proteins were restored to the pre-damage levels. Similar changes were observed in a collagenase injection-induced rat model of tendinopathy. Exogenous mitochondria incorporated into the Achilles tendon reduced inflammatory and fission marker levels. Notably, collagen production was restored. Our results demonstrate the therapeutic effects of direct mitochondrial transplantation in tendinopathy. These effects may be explained by alterations in anti-inflammatory and apoptotic processes via changes in mitochondrial dynamics.

scholarly journals SOCS-6 promotes mitochondrial fission and cardiomyocyte apoptosis and is negatively regulated by QKI mediated miR-19b

2020 ◽  
Author(s):  
Peng Zhang ◽  
Ping Guan ◽  
Xiaomiao Ye ◽  
Yi Lu ◽  
Yanwen Hang ◽  
...  
Keyword(s):  
Rna Binding ◽  
Mitochondrial Dynamics ◽  
Ischemia Reperfusion ◽  
Mitochondrial Fission ◽  
Vital Role ◽  
Cardiomyocyte Apoptosis ◽  
Luciferase Assay ◽  
Future Research

Abstract Background Ischemia/reperfusion (IR) injury following myocardial infarction can result in debilitating complications and morbidity. Mitochondrial dysfunction and abnormal mitochondrial fission have been implicated in the complications associated with IR injury as cardiomyocytes are abundant in mitochondria. SOCS-6 is known to participate in mitochondrial fragmentation but its exact involvement and the pathways associated are uncertain. Results In the present study, we examine the biological role and regulation of SOCS-6 in mitochondrial dynamics using hypoxia and reoxygenation (H/R) in cardiomyocytes and with a murine model of IR injury. We found that SOCS-6 inhibition by RNA interference attenuated H/R-induced mitochondrial fission and apoptosis in cardiomyocytes. A luciferase assay indicated that SOCS-6 is a direct target of miR-19b. The overexpression of miR-19b decreased mitochondrial fission and apoptosis in vitro . Moreover, the presence of miR-19b reduced the level of SOCS-6 and the injury caused by IR in vivo . There were less apoptotic cells in the myocardium of mice injected with miR-19b. In addition, we found that the RNA-binding protein, QKI, participates in the regulation of miR-19b expression. Conclusions Our results indicate that the inhibition of mitochondrial fission through downregulating SOCS-6 via the QKI/miR-19b/SOCS-6 pathway attenuated the damage sustained by IR. The QKI/miR-19b/SOCS-6 axis plays a vital role in regulation of mitochondrial fission and cardiomyocyte apoptosis and could form the basis of future research in the development of therapies for the management of cardiac diseases.

scholarly journals USP9X-mediated KDM4C deubiquitination promotes lung cancer radioresistance by epigenetically inducing TGF-β2 transcription

2021 ◽  
Author(s):  
Xiaohua Jie ◽  
William Pat Fong ◽  
Rui Zhou ◽  
Ye Zhao ◽  
Yingchao Zhao ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Affinity Purification ◽  
Smad Signaling ◽  
Lung Cancer Patients ◽  
Lysine Specific Demethylase ◽  
Underlying Mechanisms ◽  
H3k9me3 Level ◽  
Critical Binding

AbstractRadioresistance is regarded as the main barrier to effective radiotherapy in lung cancer. However, the underlying mechanisms of radioresistance remain elusive. Here, we show that lysine-specific demethylase 4C (KDM4C) is overexpressed and correlated with poor prognosis in lung cancer patients. We provide evidence that genetical or pharmacological inhibition of KDM4C impairs tumorigenesis and radioresistance in lung cancer in vitro and in vivo. Moreover, we uncover that KDM4C upregulates TGF-β2 expression by directly reducing H3K9me3 level at the TGF-β2 promoter and then activates Smad/ATM/Chk2 signaling to confer radioresistance in lung cancer. Using tandem affinity purification technology, we further identify deubiquitinase USP9X as a critical binding partner that deubiquitinates and stabilizes KDM4C. More importantly, depletion of USP9X impairs TGF-β2/Smad signaling and radioresistance by destabilizing KDM4C in lung cancer cells. Thus, our findings demonstrate that USP9X-mediated KDM4C deubiquitination activates TGF-β2/Smad signaling to promote radioresistance, suggesting that targeting KDM4C may be a promising radiosensitization strategy in the treatment of lung cancer.

scholarly journals All-Trans Retinoic Acid Increases DRP1 Levels and Promotes Mitochondrial Fission

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1202
Author(s):  
Bojjibabu Chidipi ◽  
Syed Islamuddin Shah ◽  
Michelle Reiser ◽  
Manasa Kanithi ◽  
Amanda Garces ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Mitochondrial Fission ◽  
Normal Function ◽  
Mitochondrial Network ◽  
Protein Levels ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid ◽  
Area And Perimeter

In the heart, mitochondrial homeostasis is critical for sustaining normal function and optimal responses to metabolic and environmental stressors. Mitochondrial fusion and fission are thought to be necessary for maintaining a robust population of mitochondria, and disruptions in mitochondrial fission and/or fusion can lead to cellular dysfunction. The dynamin-related protein (DRP1) is an important mediator of mitochondrial fission. In this study, we investigated the direct effects of the micronutrient retinoid all-trans retinoic acid (ATRA) on the mitochondrial structure in vivo and in vitro using Western blot, confocal, and transmission electron microscopy, as well as mitochondrial network quantification using stochastic modeling. Our results showed that ATRA increases DRP1 protein levels, increases the localization of DRP1 to mitochondria in isolated mitochondrial preparations. Our results also suggested that ATRA remodels the mitochondrial ultrastructure where the mitochondrial area and perimeter were decreased and the circularity was increased. Microscopically, mitochondrial network remodeling is driven by an increased rate of fission over fusion events in ATRA, as suggested by our numerical modeling. In conclusion, ATRA results in a pharmacologically mediated increase in the DRP1 protein. It also results in the modulation of cardiac mitochondria by promoting fission events, altering the mitochondrial network, and modifying the ultrastructure of mitochondria in the heart.

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