SATRD7 DEPLETION INDUCE ENDOPLASMIC RETICULUM STRESS (ER AND GOLGI APPARATUS FRAGMENTATION)

Mar del Plata

Congreso; SAIB; 2015

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. StarD7 facilitates 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 response to H2O2 treatment.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 suggest that StarD7 is involved in maintaining cell homeostasis. Supported by FONCyT, CONICET, SECyT-UNC.