title: Beclin-1 Deficiency Alters Autophagosome Formation, Lysosome Biogenesis and Enhances Neuronal Vulnerability of HT22 Hippocampal Cells.
abstract: Beclin-1 is assumed to be a critical component participating in autophagosome formation in mammals; however, the exact role of Beclin-1 in autophagy remains controversial. Here (1) we created a HT22-Beclin-1-knockdown cell line using the Q-techBECN1 technique, (2) examined the potential role of Beclin-1 in an autophagic response in hippocampal HT22 neurons challenged with rapamycin, (3) investigated the expression of several gene products involved in the autophagic pathway, and (4) checked the effects of Beclin-1 knockdown on neuronal death induced by AAS. Rapamycin induced and altered the expression of autophagy signature proteins in wild-type cultures as well as in HT22-Beclin-1-knockdown cells. However, among the examined markers, only two factors exhibited dramatic changes when comparing controls to HT22-Beclin-1-knockdown cells. The amount of LC3, an important protein for the initiation of autophagosome formation and LAMP-1, a major constituent of the lysosomal membrane, underwent a dramatic and highly significant increase in control cultures challenged with rapamycin. In contrast, rapamycin was not able to induce any significant changes in LC3 and LAMP-1 levels in HT22-Beclin-1-knockdown cells. In addition, the knockdown of Beclin-1 enhanced neuronal susceptibility to death signals induced by AAS. Our data demonstrate the essential role of Beclin-1 in the formation of autophagosomes and lysosome biogenesis and underline that deletion of this key system is deleterious for cell viability.
authors.affiliation: Institut für Zelluläre und Molekulare Anatomie (Anatomie III), Klinikum der Johann Wolfgang von Goethe-Universität, Theodor-Stern-Kai 7, 60590, Frankfurt/Main, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Fekadu
authors.affiliation: Institut für Zelluläre und Molekulare Anatomie (Anatomie III), Klinikum der Johann Wolfgang von Goethe-Universität, Theodor-Stern-Kai 7, 60590, Frankfurt/Main, Germany. rami@em.uni-frankfurt.de.
authors.forename: A
authors.initials: A
authors.lastname: Rami
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D000071182:Autophagosomes / Q000187:drug effects / Q000378:metabolism*; D000071183:Autophagy-Related Proteins / Q000378:metabolism; D000071186:Beclin-1 / Q000172:deficiency* / Q000378:metabolism; D002401:Cathepsin B / Q000378:metabolism; D002452:Cell Count; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006624:Hippocampus / Q000166:cytology*; D006801:Humans; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D000071456:Sequestosome-1 Protein / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D025801:Ubiquitin / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism; D052118:Lysosomal-Associated Membrane Protein 1
chemical_list: D000071183:Autophagy-Related Proteins; D000071186:Beclin-1; D002401:Cathepsin B; D051907:Lysosomal Membrane Proteins; D000071456:Sequestosome-1 Protein; D020123:Sirolimus; D025801:Ubiquitin; D033921:Vesicular Transport Proteins; C561107:Atg14 protein, mouse; C052255:Lamp1 protein, mouse; D052118:Lysosomal-Associated Membrane Protein 1; C101343:Sqstm1 protein, mouse
keywords: Autophagy; Beclin-1; HT22 cells; LAMP-1; Neuronal vulnerability