ALBERT

Description:    Autophagy has been described as a cellular response to stressful stimuli like starvation. One of its primary functions is to recycle amino acids from degraded proteins for cellular survival under nutrient deprived conditions. Autophagy is characterized by double membrane cytosolic vesicles called autophagosomes and prolonged autophagy is known to result in autophagic (Type II) cell death. Beclin-1 is involved in the regulation of autophagy in mammalian cells. This study examined the potential impact of knockdown of Beclin-1 in an autophagic response in HT22 neurons challenged with amino acid starvation (AAS). AAS exposure induced light chain-3 (LC-3)-immunopositive and monodansylcadaverine (MDC) fluorescent dye-labeled autophagosome formation in cell bodies as early as 3 h post-AAS in wild type cells. Elevated levels of the autophagosome-targeting LC3-II were also observed following AAS. In addition, neuronal death induced by AAS in HT22-cells led to a moderate activation of caspase-3, a slight upregulation of AIF and did not alter the HtrA2 levels. Autophagy inhibition by a knockdown of Beclin-1 significantly reduced AAS-induced LC3-II increase, reduced accumulation of autophagosomes, and potentiated AAS-mediated neuronal death. Collectively, this study shows that the both apoptotic and autophagic machineries are inducible in cultured hippocampal HT22 neurons subjected to AAS. Our data further show that attenuation of autophagy by a knockdown of Beclin-1 enhanced neurons susceptibility to proapoptotic signals induced by AAS and underlines that autophagy is per se a protective than a deleterious mechanism. Content Type Journal Article Category Original Paper Pages 1-10 DOI 10.1007/s00418-012-1013-5 Authors M. Kim, Dr. Senckenbergische Anatomie, Institute of Cellular and Molecular Anatomy, Wolfgang Goethe-University, Anatomie III, Universitätsklinikum, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany J. Fekadu, Dr. Senckenbergische Anatomie, Institute of Cellular and Molecular Anatomy, Wolfgang Goethe-University, Anatomie III, Universitätsklinikum, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany E. Maronde, Dr. Senckenbergische Anatomie, Institute of Cellular and Molecular Anatomy, Wolfgang Goethe-University, Anatomie III, Universitätsklinikum, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany A. Rami, Dr. Senckenbergische Anatomie, Institute of Cellular and Molecular Anatomy, Wolfgang Goethe-University, Anatomie III, Universitätsklinikum, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany Journal Histochemistry and Cell Biology Online ISSN 1432-119X Print ISSN 0948-6143