Transient knockdown of presenilin-1 provokes endoplasmic reticulum stress related formation of autophagosomes in HepG2 cells.
The involvement of presenilins in the endoplasmic reticulum (ER) related autophagy was investigated by their transient knockdown in HepG2 cells. The silencing of PSEN1 but not of PSEN2 led to cell growth impairment and decreased viability. PSEN1 silencing resulted in ER stress response as evidenced by the elevated levels of glucose regulated protein 78 (Grp78), protein disulfide isomerase (PDI), and CCAAT/enhancer-binding protein homologous protein (CHOP) and by the activation of activating transcription factor 6 (ATF6). The activation of autophagy was indicated by the increased procession of microtubule-associated light chain 3 protein isoform B (LC3B) and by decreased phosphorylation of mammalian target of rapamycin (mTOR) and 70kDa ribosomal protein S6 kinase (p70S6K). Formation of ER-related cytoplasmic vacuolization colocalizing with the autophagic marker LC3B was also observed. The morphological effects and LC3B activation in presenilin-1 knockdown cells could be prevented by using the phosphoinositide 3-kinase (PI3K) inhibitor wortmannin or by calcium chelation. The results show that presenilin-1 hampers the ER stress dependent initiation of macroautophagy.
Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.
Péter
P
Száraz
Gábor
G
Bánhegyi
Paola
P
Marcolongo
Angelo
A
Benedetti
D001343:Autophagy; D002118:Calcium / Q000378:metabolism; D049109:Cell Proliferation; D002470:Cell Survival; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress; D056945:Hep G2 Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D053764:Presenilin-1 / Q000235:genetics*; D034622:RNA Interference
D002118:Calcium; D000091342:Endoplasmic Reticulum Chaperone BiP; D008869:Microtubule-Associated Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D053764:Presenilin-1; C000717247:HSPA5 protein, human; C502070:MAP1LC3B protein, human
Autophagy; Calcium; ER stress; Endoplasmic reticulum; PI3K; Presenilin