Delta-lactoferrin induces cell death via the mitochondrial death signaling pathway by upregulating bax expression.
Delta-lactoferrin (∆Lf) is a transcription factor belonging to the lactoferrin family, the expression of which inhibits cell proliferation and leads to Skp1 and DcpS gene transactivation. In this study, we showed that ∆Lf expression also induces cell death via apoptosis in HEK 293 and MCF7 cells using a cell viability assay and DNA fragmentation. Western blot analyses showed that apoptosis was caspase-9, 7 and 8 dependent. Proteolytic cleavage of the endonuclease PARP was significantly increased. The levels of expression of Bcl family members were detected by immunochemistry and showed that the Bcl-xl/Bax and Bcl-2/Bax protein ratios were decreased. We determined that the pro-apoptotic effects of ∆Lf are mainly mediated by the activation of the mitochondria-dependent death-signaling pathway. Apoptosis induction by ∆Lf is concomitant with increased cellular levels of Bax protein. Analysis of the Bax promoter region detected a ∆Lf response element located at -155 bp from the transcription start site. Both luciferase reporter gene and chromatin immunoprecipitation assays confirmed that ∆Lf interacts in vitro and in vivo specifically with this sequence. Its deletion, realized using directed mutagenesis, totally abolished ∆Lf transcriptional activity, identifying it as a ∆Lf-responsive element. These results indicate that the Bax gene is a novel ∆Lf target. Moreover we also showed that the O-GlcNAc/P interplay, which controls ∆Lf transcriptional activity, modulates Bax transactivation.
Unité de Glycobiologie Structurale et Fonctionnelle (UGSF), UMR 8576 CNRS, Université des Sciences et Technologies de Lille (USTL), IFR-147, 59655, Villeneuve d'Ascq, France.
Stéphan
S
Hardivillé
Adelma
A
Escobar-Ramirez
Soccoro
S
Pina-Canceco
Elisabeth
E
Elass
Annick
A
Pierce
D000215:Acylation; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D007781:Lactoferrin / Q000008:administration & dosage / Q000235:genetics / Q000502:physiology*; D061986:MCF-7 Cells; D008928:Mitochondria / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000008:administration & dosage / Q000235:genetics / Q000502:physiology; D015533:Transcriptional Activation; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000502:physiology*; D019014:fas Receptor / Q000235:genetics / Q000502:physiology
C494826:BAX protein, human; C491901:FAS protein, human; C490098:LTF protein, human; D020033:Protein Isoforms; D051028:bcl-2-Associated X Protein; D019014:fas Receptor; D007781:Lactoferrin