title: Sustained Action of Ceramide on the Insulin Signaling Pathway in Muscle Cells: IMPLICATION OF THE DOUBLE-STRANDED RNA-ACTIVATED PROTEIN KINASE.
abstract: In vivo, ectopic accumulation of fatty acids in muscles leads to alterations in insulin signaling at both the IRS1 and Akt steps. However, in vitro treatments with saturated fatty acids or their derivative ceramide demonstrate an effect only at the Akt step. In this study, we adapted our experimental procedures to mimic the in vivo situation and show that the double-stranded RNA-dependent protein kinase (PKR) is involved in the long-term effects of saturated fatty acids on IRS1. C2C12 or human muscle cells were incubated with palmitate or directly with ceramide for short or long periods, and insulin signaling pathway activity was evaluated. PKR involvement was assessed through pharmacological and genetic studies. Short-term treatments of myotubes with palmitate, a ceramide precursor, or directly with ceramide induce an inhibition of Akt, whereas prolonged periods of treatment show an additive inhibition of insulin signaling through increased IRS1 serine 307 phosphorylation. PKR mRNA, protein, and phosphorylation are increased in insulin-resistant muscles. When PKR activity is reduced (siRNA or a pharmacological inhibitor), serine phosphorylation of IRS1 is reduced, and insulin-induced phosphorylation of Akt is improved. Finally, we show that JNK mediates ceramide-activated PKR inhibitory action on IRS1. Together, in the long term, our results show that ceramide acts at two distinct levels of the insulin signaling pathway (IRS1 and Akt). PKR, which is induced by both inflammation signals and ceramide, could play a major role in the development of insulin resistance in muscle cells.
authors.affiliation: From INSERM, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Université Paris Descartes, Sorbonne Paris Cité, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France.
authors.forename: Rima
authors.initials: R
authors.lastname: Hage Hassan
authors.affiliation: From INSERM, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Université Paris Descartes, Sorbonne Paris Cité, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France.
authors.forename: Ana Catarina
authors.initials: AC
authors.lastname: Pacheco de Sousa
authors.affiliation: From INSERM, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Université Paris Descartes, Sorbonne Paris Cité, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France.
authors.forename: Rana
authors.initials: R
authors.lastname: Mahfouz
authors.affiliation: From INSERM, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Université Paris Descartes, Sorbonne Paris Cité, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Hainault
authors.affiliation: Department of Physiology, Medical University of Bialystok, 15-222 Bialystok, Poland, Assistance Publique-Hôpitaux de Paris.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Blachnio-Zabielska
authors.affiliation: From INSERM, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Université Paris Descartes, Sorbonne Paris Cité, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Département de Diabétologie et Maladies Métaboliques and.
authors.forename: Olivier
authors.initials: O
authors.lastname: Bourron
authors.affiliation: Service de Chirurgie Vasculaire,Hôpital Pitié-Salpêtrière, 75013 Paris, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Koskas
authors.affiliation: Department of Physiology, Medical University of Bialystok, 15-222 Bialystok, Poland, Assistance Publique-Hôpitaux de Paris.
authors.forename: Jan
authors.initials: J
authors.lastname: Górski
authors.affiliation: From INSERM, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Université Paris Descartes, Sorbonne Paris Cité, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Ferré
authors.affiliation: From INSERM, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Université Paris Descartes, Sorbonne Paris Cité, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Foufelle
authors.affiliation: From INSERM, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, Université Paris Descartes, Sorbonne Paris Cité, Unité Mixte de Recherche_S 1138, Centre de Recherche des Cordeliers, 75006 Paris, France, eric.hajduch@crc.jussieu.fr.
authors.forename: Eric
authors.initials: E
authors.lastname: Hajduch
mesh_terms: D000818:Animals; D002460:Cell Line; D002518:Ceramides / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000235:genetics / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000502:physiology*; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism*
chemical_list: D002518:Ceramides; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D019892:eIF-2 Kinase; C000605978:protein kinase R, mouse; D048670:MAP Kinase Kinase 4
keywords: Akt PKB; ceramide; insulin signaling; protein kinase RNA-activated (PKR); skeletal muscle; type 2 diabetes