CIBICI   14215
CENTRO DE INVESTIGACION EN BIOQUIMICA CLINICA E INMUNOLOGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Role of StarD7 in mitochondrial dynamics
Autor/es:
ANDREA MIRANDA; SUSANA GENTI DE RAIMONDI; MARIANO CRUZ DEL PUERTO; GRACIELA PANZETTA DE DUTARI; MARÍA LAURA ROJAS; LUCILE KOURDOVA
Lugar:
Salta
Reunión:
Congreso; LV Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2019
Institución organizadora:
SAIB
Resumen:
Mitochondria are dynamic organelles crucial for cell function and survival implicated in oxidative energy production. Mitochondrial lipids affect several important functions such as respiratory metabolism, membrane architecture, protein import, mitophagy, and mitochondrial dynamics. StarD7.I is a lipid transport protein isoform that has a mitochondrial targeting signal involved in phosphatidylcholine (PC) delivery to the mitochondria. Previous studies have shown that StarD7 knockdown induces alterations in mitochondria and endoplasmic reticulum morphology with a reduction in mitochondrial PC content, however, how different StarD7 levels affect the mitochondrial dynamics has been not explored yet. Here, we generated two HTR8/SVneo stable cell lines expressing the mitochondrial StarD7.I or the cytosolic StarD7.II isoforms. We demonstrated that StarD7.I overexpression promotes altered mitochondrial morphology with a significant increase in mitochondrial fragmentation, whereas no changes were observed in stable StarD7.II cells compared to control cells. These data were confirmed by immunofluorescence analysis in HTR8/SVneo wild type cells transiently transfected with the bicistronic p-Lenti-StarD7.I-IRES-EGFP or p-Lenti-StarD7.II-IRES-EGFP plasmids. Mitochondrial targeting photoactivatable (PA-GFP) protein assays indicated that mitochondria are able to yield fusions with higher motility in StarD7.I-overexpressing cells than those in control cells. Stable StarD7.I cells maintain the mitochondrial membrane potential and produce lower ROS generation than control cells. Additionally, an increase in the expression of Drp1 and Mfn2 proteins was established in StarD7.I cells. In contrast, the amount of Mfn1 was decreased and no changes were observed in PGC1α protein levels. Moreover, the overexpression of Drp1K38A, used to induce Drp1 loss-of-function, promotes mitochondrial network invariably to collapse into large perinuclear aggregates, inhibiting StarD7 overexpression-induced mitochondrial fragmentation. These results indicate that StarD7 overexpression-mediated mitochondrial fragmentation occurs in a fission-dependent manner via Drp1. Nocodazole treatment separates the aggregates showing how mutant Drp1 affects the mitochondria morphology. Finally, StarD7 silencing leads to mitochondrial fragmentation with a donut phenotype, without motility and an increase in ROS generation. In this condition, the Mfn2 level was decreased without modifications in Drp1, Mfn1, and PGC1α proteins. Altogether these findings indicate that alterations in StarD7.I expression produce significant changes in the proteins that control the mitochondrial morphology impacting mitochondrial dynamics. Granted by FONCyT, SECyT-UNC.