Repression of the miR-17-92 cluster by p53 has an important function in hypoxia-induced apoptosis

Yan, Hongli; Geng, Xue; Mei, Qian; Wang, Yu‐Zhao; Ding, Fei-Xiang; Lin, Li; Lu, Minghua; Tang, Ying; Yu, Hong‐Yu; Sun, Shuhan

doi:10.1038/emboj.2009.214

Cited by 276 publications

(222 citation statements)

References 57 publications

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“…PS exposure in the erythrocytes was assessed by the Annexin V/ PI detection kit (Beyotime, Nantong, China) as described previously [58,59]. The images of the annexin binding cells were captured by the fluorescent microscope.…”

Section: Measurement Of Apoptosismentioning

confidence: 99%

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The metabolites of glutamine prevent hydroxyl radical-induced apoptosis through inhibiting mitochondria and calcium ion involved pathways in fish erythrocytes

Jiang

Liu

et al. 2016

Free Radical Biology and Medicine

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a b s t r a c tThe present study explored the apoptosis pathways in hydroxyl radicals ( • OH)-induced carp erythrocytes. Carp erythrocytes were treated with the caspase inhibitors in physiological carp saline (PCS) or Ca 2 þ -free PCS in the presence of 40 μM FeSO 4 /20 μM H 2 O 2 . The results showed that the generation of reactive oxygen species (ROS), the release of cytochrome c and DNA fragmentation were caspase-dependent, and Ca 2 þ was involved in calpain activation and phosphatidylserine (PS) exposure in • OH-induced carp erythrocytes. Moreover, the results suggested that caspases were involved in PS exposure, and Ca 2 þ was involved in DNA fragmentation in • OH-induced fish erythrocytes. These results demonstrated that there might be two apoptosis pathways in fish erythrocytes, one is the caspase and cytochrome c-dependent apoptosis that is similar to that in mammal nucleated cells, the other is the Ca 2 þ -involved apoptosis that was similar to that in mammal non-nucleated erythrocytes. So, fish erythrocytes may be used as a model for studying oxidative stress and apoptosis in mammal cells. Furthermore, the present study investigated the effects of glutamine (Gln)'s metabolites [alanine (Ala), citrulline (Cit), proline (Pro) and their combination (Ala 10 Pro 4 Cit 1 )] on the pathways of apoptosis in fish erythrocytes. The results displayed that Ala, Cit, Pro and Ala 10 Pro 4 Cit 1 effectively suppressed ROS generation, cytochrome c release, activation of caspase-3, caspase-8 and caspase-9 at the physiological concentrations, prevented Ca 2 þ influx, calpain activation, PS exposure, DNA fragmentation and the degradation of the cytoskeleton and oxidation of membrane and hemoglobin (Hb) and increased activity of anti-hydroxyl radical (AHR) in • OH-induced carp erythrocytes. Ala 10 Pro 4 Cit 1 produced a synergistic effect of inhibited oxidative stress and apoptosis in fish erythrocytes. These results demonstrated that Ala, Cit, Pro and their combination can protect mammal erythrocytes and nucleated cells against oxidative stress and apoptosis. The studies supported the use of Gln, Ala, Cit and Pro as oxidative stress and apoptosis inhibitors in mammal cells and the hypothesis that the inhibited effects of Gln on oxidative stress and apoptosis are at least partly dependent on that of its metabolites in mammalian.

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Section: Measurement Of Apoptosismentioning

confidence: 99%

“…The number of annexin binding cells is a widely used index of PS exposure [59]. There may be a positive connection between PS exposure and Ca 2 þ levels in fish erythrocytes.…”

Section: • Oh-induced Apoptosis In Fish Erythrocytesmentioning

confidence: 99%

The metabolites of glutamine prevent hydroxyl radical-induced apoptosis through inhibiting mitochondria and calcium ion involved pathways in fish erythrocytes

Jiang

Liu

et al. 2016

Free Radical Biology and Medicine

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“…12 Known major activators of the miR-17-92 cluster are transcription factor c-MYC and members of the E2F family, whereas p53 acts as a repressor under hypoxic conditions. [22][23][24][25] As PHLPP2 phosphatases are potential therapeutic targets, it is important to understand mechanisms that regulate PHLPP2 protein expression. Most recent investigations of this tumor-suppressor family have focused primarily on its regulation in solid tumors and their derivative cell lines, rather than in hematological malignancies.…”

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confidence: 99%

Transcription factor C/EBP-β induces tumor-suppressor phosphatase PHLPP2 through repression of the miR-17–92 cluster in differentiating AML cells

et al. 2016

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PHLPP2, a member of the PH-domain leucine-rich repeat protein phosphatase (PHLPP) family, which targets oncogenic kinases, has been actively investigated as a tumor suppressor in solid tumors. Little is known, however, regarding its regulation in hematological malignancies. We observed that PHLPP2 protein expression, but not its mRNA, was suppressed in late differentiation stage acute myeloid leukemia (AML) subtypes. MicroRNAs (miR or miRNAs) from the miR-17-92 cluster, oncomir-1, were shown to inhibit PHLPP2 expression and these miRNAs were highly expressed in AML cells that lacked PHLPP2 protein.Studies showed that miR-17-92 cluster regulation was, surprisingly, independent of transcription factors c-MYC and E2F in these cells; instead all-trans-retinoic acid (ATRA), a drug used for terminally differentiating AML subtypes, markedly suppressed miR-17-92 expression and increased PHLPP2 protein levels and phosphatase activity. Finally, we demonstrate that the effect of ATRA on miR-17-92 expression is mediated through its target, transcription factor C/EBPβ, which interacts with the intronic promoter of the miR-17-92 gene to inhibit transactivation of the cluster. These studies reveal a novel mechanism for upregulation of the phosphatase activity of PHLPP2 through C/EBPβ-mediated repression of the miR-17-92 cluster in terminally differentiating myeloid cells. Phosphatases are pivotal components of intracellular signaling cascades, controlling essential processes like metabolism, apoptosis, proliferation and differentiation. 1 The PH-domain leucine-rich repeat protein phosphatase (PHLPP) family serine-threonine phosphatases are emerging as central factors in cell survival and death regulation. The PHLPP2 is a member of this family. 2,3 To date four PHLPP substrates, Akt, PKC, Mst1 and S6K1, have been identified, all kinases involved in cell survival or apoptosis. 4-7 Dephosphorylation inactivates Akt, S6K1 and PKC, and subsequently cell survival signaling, whereas dephosphorylation of Mst1 activates its apoptotic function.PHLPP protein expression and activity is suppressed through various mechanisms in cancers. Although most studies on PHLPP2 have focused on genetic alterations in solid tumors, 8 PHLPP2 protein expression in small cell lung and colorectal cancers is also restricted through translational suppression 9 and post-transcriptional control by microRNAs (miR or miRNAs), miR-205 and miR-224. 10,11 The PHLPP2 3' untranslated region (3'UTR) harbors complementary binding sites for a subset of miRNAs belonging to the miRNA-17-92 cluster. 12 This cluster comprises six miRNAs on chromosome 13, transcribed as a single polycistronic unit. 13,14 Also known as oncomir-1, the cluster enhances cell proliferation or inhibits apoptosis by suppressing targets such as Bim, E2F1 and PTEN and is markedly overexpressed in human cancers. [15][16][17][18][19][20][21] Reduced levels of PHLPP2 in chemoresistant miR-17-92 overexpressing mantle cell lymphomas had suggested that the phosphatase could be a target of oncomir-1. 12 Kno...

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“…miR-206 prevents apoptosis by targeting notch3 35 . The miR-17-92 cluster is a novel target for p53-mediated transcriptional repression 36 . In addition, p53 is also regulated by miR-125b 37 .…”

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confidence: 99%

miR-484 regulates mitochondrial network through targeting Fis1

et al. 2012

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mitochondria constantly undergo fusion and fission, two necessary processes for the maintenance of organelle fidelity. The abnormal mitochondrial fission participates in the pathogenesis of many diseases, but its regulation remains poorly understood. Here we show that miR-484 can suppress translation of mitochondrial fission protein Fis1, and inhibit Fis1-mediated fission and apoptosis in cardiomyocytes and in the adrenocortical cancer cells. We demonstrate that Fis1 is necessary for mitochondrial fission and apoptosis, and is upregulated during anoxia, whereas miR-484 is downregulated. miR-484 is able to attenuate Fis1 upregulation and mitochondrial fission, by binding to the amino acid coding sequence of Fis1 and inhibiting its translation. In exploring the underlying mechanism of miR-484 downregulation upon apoptosis, we observe that Foxo3a transactivates miR-484 expression. Foxo3a transgenic or knockout mice exhibit, respectively, a high or low level of miR-484 and a reduced or enhanced mitochondrial fission, apoptosis and myocardial infarction. our data reveal a model of mitochondrial fission regulation by a microRnA.

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Repression of the miR-17-92 cluster by p53 has an important function in hypoxia-induced apoptosis

Cited by 276 publications

References 57 publications

The metabolites of glutamine prevent hydroxyl radical-induced apoptosis through inhibiting mitochondria and calcium ion involved pathways in fish erythrocytes

The metabolites of glutamine prevent hydroxyl radical-induced apoptosis through inhibiting mitochondria and calcium ion involved pathways in fish erythrocytes

Transcription factor C/EBP-β induces tumor-suppressor phosphatase PHLPP2 through repression of the miR-17–92 cluster in differentiating AML cells

miR-484 regulates mitochondrial network through targeting Fis1

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