Publications by authors named "Evanthia Pangou"

3 Publications

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A PKD-MFF signaling axis couples mitochondrial fission to mitotic progression.

Cell Rep 2021 May;35(7):109129

Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France; Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France; Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France; Université de Strasbourg, Strasbourg, France. Electronic address:

Mitochondria are highly dynamic organelles subjected to fission and fusion events. During mitosis, mitochondrial fission ensures equal distribution of mitochondria to daughter cells. If and how this process can actively drive mitotic progression remains largely unknown. Here, we discover a pathway linking mitochondrial fission to mitotic progression in mammalian cells. The mitochondrial fission factor (MFF), the main mitochondrial receptor for the Dynamin-related protein 1 (DRP1), is directly phosphorylated by Protein Kinase D (PKD) specifically during mitosis. PKD-dependent MFF phosphorylation is required and sufficient for mitochondrial fission in mitotic but not in interphasic cells. Phosphorylation of MFF is crucial for chromosome segregation and promotes cell survival by inhibiting adaptation of the mitotic checkpoint. Thus, PKD/MFF-dependent mitochondrial fission is critical for the maintenance of genome integrity during cell division.
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http://dx.doi.org/10.1016/j.celrep.2021.109129DOI Listing
May 2021

HIF-2α phosphorylation by CK1δ promotes erythropoietin secretion in liver cancer cells under hypoxia.

J Cell Sci 2016 11 29;129(22):4213-4226. Epub 2016 Sep 29.

Laboratory of Biochemistry, Faculty of Medicine, University of Thessaly, Biopolis, Larissa 41500, Greece

Hypoxia inducible factor 2 (HIF-2) is a transcriptional activator implicated in the cellular response to hypoxia. Regulation of its inducible subunit, HIF-2α (also known as EPAS1), involves post-translational modifications. Here, we demonstrate that casein kinase 1δ (CK1δ; also known as CSNK1D) phosphorylates HIF-2α at Ser383 and Thr528 in vitro We found that disruption of these phosphorylation sites, and silencing or chemical inhibition of CK1δ, reduced the expression of HIF-2 target genes and the secretion of erythropoietin (EPO) in two hepatic cancer cell lines, Huh7 and HepG2, without affecting the levels of HIF-2α protein expression. Furthermore, when CK1δ-dependent phosphorylation of HIF-2α was inhibited, we observed substantial cytoplasmic mislocalization of HIF-2α, which was reversed upon the addition of the nuclear protein export inhibitor leptomycin B. Taken together, these data suggest that CK1δ enhances EPO secretion from liver cancer cells under hypoxia by modifying HIF-2α and promoting its nuclear accumulation. This modification represents a new mechanism of HIF-2 regulation that might allow HIF isoforms to undertake differing functions.
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http://dx.doi.org/10.1242/jcs.191395DOI Listing
November 2016

Endothelin-1 (ET-1) induces resistance to bortezomib in human multiple myeloma cells via a pathway involving the ETB receptor and upregulation of proteasomal activity.

J Cancer Res Clin Oncol 2016 Oct 16;142(10):2141-58. Epub 2016 Aug 16.

Department of Medical Oncology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Biopolis, 41110, Larissa, Greece.

Purpose: Bortezomib (BTZ) is used for the treatment of multiple myeloma (MM). However, a significant proportion of patients may be refractory to the drug. This study aimed to investigate whether the endothelin (ET-1) axis may act as an escape mechanism to treatment with bortezomib in MM cells.

Methods: NCI-H929 and RPMI-8226 (human MM cell lines) were cultured with or without ET-1, BTZ, and inhibitors of the endothelin receptors. ET-1 levels were determined by ELISA, while the protein levels of its receptors and of the PI3K and MAPK pathways' components by western blot. Effects of ET-1 on cell proliferation were studied by MTT and on the ubiquitin proteasome pathway by assessing the chymotryptic activity of the 20S proteasome in cell lysates.

Results: Endothelin receptors A and B (ETAR and ETBR, respectively) were found to be expressed in both cell lines, with the RPMI-8226 cells that are considered resistant to BTZ, expressing higher levels of ETBR and in addition secreting ET-1. Treatment of the NCI-H929 cells with ET-1 increased proliferation, while co-incubation of these cells with ET-1 and BTZ decreased BTZ efficacy with concomitant upregulation of 20S proteasomal activity. Si-RNA silencing or chemical blockade of ETBR abrogated the protective effects of ET-1. Finally, data suggest that the predominant signaling pathway involved in ET-1/ETBR-induced BTZ resistance in MM cells may be the MAPK pathway.

Conclusion: Our data suggest a possible role of the ET-1/ETBR axis in regulating the sensitivity of MM cells to BTZ. Thus, combining bortezomib with strategies to target the ET-1 axis could prove to be a novel promising therapeutic approach in MM.
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http://dx.doi.org/10.1007/s00432-016-2216-2DOI Listing
October 2016
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