Interactions of the transcription factors c-Fos and c-Jun with phospholipid vesicles

Campinas

Otro; Reporte Anual de Actividad Sincrotron; 2006

Laboratorio Nacional de Luz Sincrotron

c-Fos and c-Jun are Immediate Early Gene products thatdimerize to form the transcription complex Activator Protein-1 (AP-1).The interaction of AP-1 with biointerfaces lies at thecore of its biological functions in normal and oncogenic cellularprocesses [1]. In addition, as a monomer and independentlyof transcriptional activity, c-Fos associates to endoplasmicreticulum -that is, a membrane interface- to activate phospholipidmetabolism [2]. On the other hand, both c-Fos and c-Jun are surface active, and their dimer AP-1 is stabilized by interfaces.c-Fos is further stabilized through differential interactionswith phospholipid interfaces and responds to changesin membrane packing and composition through molecular reordering,evidencing its ability to sense and transduce information[3][4][5][6]. Specific interactions induce condensationand depolarization with phosphatidylinositol diphosphate(PIP2) or expansion and hyperpolarization with phosphadityilcholine (DMPC), of c-Fos mixtures with these phospholipids.Such alterations affect other membrane componentslike the activity of phospholipases mediating signal transductionevents [7][8]. In contrast, c-Jun interacts with phospholipidsin a non selective way. We wanted to extend our observationsto bilayers. Exploiting the potential of SAXS tostudy colloidal systems, we have applied the technique to proteoliposomes,in order to evaluate possible changes in lipidpacking induced by c-Fos or c-Jun that may affect processesat the membrane level.