title: The stress oncoprotein LEDGF/p75 interacts with the methyl CpG binding protein MeCP2 and influences its transcriptional activity.
abstract: The lens epithelium-derived growth factor p75 (LEDGF/p75) is a transcription coactivator that promotes resistance to oxidative stress- and chemotherapy-induced cell death. LEDGF/p75 is also known as the dense fine speckles autoantigen of 70 kDa (DFS70) and has been implicated in cancer, HIV-AIDS, autoimmunity, and inflammation. To gain insights into mechanisms by which LEDGF/p75 protects cancer cells against stress, we initiated an analysis of its interactions with other transcription factors and the influence of these interactions on stress gene activation. We report here that both LEDGF/p75 and its short splice variant LEDGF/p52 interact with MeCP2, a methylation-associated transcriptional modulator, in vitro and in various human cancer cells. These interactions were established by several complementary approaches: transcription factor protein arrays, pull-down and AlphaScreen assays, coimmunoprecipitation, and nuclear colocalization by confocal microscopy. MeCP2 was found to interact with the N-terminal region shared by LEDGF/p75 and p52, particularly with the PWWP-CR1 domain. Like LEDGF/p75, MeCP2 bound to and transactivated the Hsp27 promoter (Hsp27pr). LEDGF/p75 modestly enhanced MeCP2-induced Hsp27pr transactivation in U2OS osteosarcoma cells, whereas this effect was more pronounced in PC3 prostate cancer cells. LEDGF/p52 repressed Hsp27pr activity in U2OS cells. Interestingly, siRNA-induced silencing of LEDGF/p75 in U2OS cells dramatically elevated MeCP2-mediated Hsp27pr transactivation, whereas this effect was less pronounced in PC3 cells depleted of LEDGF/p75. These results suggest that the LEDGF/p75-MeCP2 interaction differentially influences Hsp27pr activation depending on the cellular and molecular context. These findings are of significance in understanding the contribution of this interaction to the activation of stress survival genes.
authors.affiliation: Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
authors.forename: Lai Sum
authors.initials: LS
authors.lastname: Leoh
authors.forename: Bart
authors.initials: B
authors.lastname: van Heertum
authors.forename: Jan
authors.initials: J
authors.lastname: De Rijck
authors.forename: Maria
authors.initials: M
authors.lastname: Filippova
authors.forename: Leslimar
authors.initials: L
authors.lastname: Rios-Colon
authors.forename: Anamika
authors.initials: A
authors.lastname: Basu
authors.forename: Shannalee R
authors.initials: SR
authors.lastname: Martinez
authors.forename: Sandy S
authors.initials: SS
authors.lastname: Tungteakkhun
authors.forename: Valeri
authors.initials: V
authors.lastname: Filippov
authors.forename: Frauke
authors.initials: F
authors.lastname: Christ
authors.forename: Marino
authors.initials: M
authors.lastname: De Leon
authors.forename: Zeger
authors.initials: Z
authors.lastname: Debyser
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Casiano
mesh_terms: D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051783:Methyl-CpG-Binding Protein 2 / Q000235:genetics* / Q000378:metabolism; D015513:Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D021381:Protein Transport; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D055551:HSP27 Heat-Shock Proteins; D036341:Intercellular Signaling Peptides and Proteins; D051783:Methyl-CpG-Binding Protein 2; D015513:Oncogene Proteins; C119380:lens epithelium-derived growth factor