STARD7 DEPLETIONINDUCES ENDOPLASMIC RETICULUM STRESS (ER) AND GOLGI APPARATUS FRAGMENTATION´C

FLORES-MARTÍN, JESICA; CRUZ DEL PUERTO, MARIANO; REYNA, LUCIANA; ÁLVAREZ, CECILIA; PANZETTA-DUTARI, GRACIELA MARÍA; GENTI-RAIMONDI, SUSANA

Mar del Plata

Congreso; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Lipid and protein transport between organelles is an essential process in the organization of the different cell compartments. StarD7 is an intracellular lipid transport protein, member of the START domain superfamily, which is involved in many physiological processes such as lipid transfer, metabolism, and modulation of signaling pathways. StarD7facilitates the delivery of phosphatidylcholine to the mitochondria and previous results indicated that StarD7 silencing decreased ABCG2 multidrug transporter level, cell migration, proliferation, and phospholipid synthesis. Also, StarD7 silencing produced an increase in basal ROS as well as in H2O2-induced ROS levels. Here, we report that HepG2 cells transfected with StarD7 siRNA during 72 h and analyzed by transmission electron microscopy showed altered mitochondria and ER morphology. These changes were accompanied with an ER stress response measured by augmented expression levels of inositol-requiring enzyme 1 (IRE1α), calnexin, glucose regulated protein 78/immunoglobulin heavy chain-binding protein (Grp78/BiP), and protein kinase-like ER kinase (PERK). In addition, immunofluorescence assay revealed that StarD7 knockdown induced Golgi apparatus fragmentation, labeled by anti-Giantin. In summary, our results provide novel evidence for an important role of StarD7 in maintaining cell homeostasis. Supported by FONCyT, CONICET, SECyT-UNC.