title: Beclin 1 knockdown inhibits autophagic activation and prevents the secondary neurodegenerative damage in the ipsilateral thalamus following focal cerebral infarction.
abstract: Cerebral infarction can cause secondary degeneration of thalamus and delay functional recovery. However, the mechanisms underlying secondary degeneration are unclear. The present study aimed to determine the occurrence and contribution of autophagy to the thalamic degeneration after cerebral infarction. Focal cerebral infarction was induced by distal middle cerebral artery occlusion (MCAO). Autophagic activation, Beclin 1 expression and amyloid β (Aβ) deposits were determined by immunofluorescence, immunoblot and electron microscopy. Secondary damage to thalamus was assessed with Nissl staining and immunofluorescence analysis. Apoptosis was determined using TUNEL staining. The contribution of autophagy to the secondary damage was evaluated by shRNA-mediated downregulation of Beclin 1 and the autophagic inhibitor, 3-methyladenine (3-MA). The potential role of Aβ in autophagic activation was determined with N-[N-(3, 5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT). The results showed that the conversion of LC3-II, the formation of autophagosomes, and the levels of activated cathepsin B and Beclin 1 were significantly increased in the ipsilateral thalamus at 7 and 14 days after MCAO (p < 0.05 or 0.01). Both Beclin 1 knockdown and 3-MA treatment significantly reduced LC3-II conversion and autophagosome formation, which were accompanied by obvious decreases in neuronal loss, gliosis and apoptosis in the ipsilateral thalamus (p < 0.05 or 0.01). Additionally, DAPT treatment markedly reduced Aβ deposits, which coincided with decreases in LC3-II conversion and autophagosome formation (p < 0.01). These results suggest that inhibition of autophagy by Beclin 1 knockdown can attenuate the secondary thalamic damage after focal cerebral infarction. Furthermore, Aβ deposits may be involved in the activation of autophagy.
authors: Department of Neurology and Stroke Center, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors: Shihui
authors: S
authors: Xing
authors: Yusheng
authors: Y
authors: Zhang
authors: Jingjing
authors: J
authors: Li
authors: Jian
authors: J
authors: Zhang
authors: Yiliang
authors: Y
authors: Li
authors: Chao
authors: C
authors: Dang
authors: Chuo
authors: C
authors: Li
authors: Yuhua
authors: Y
authors: Fan
authors: Jian
authors: J
authors: Yu
authors: Zhong
authors: Z
authors: Pei
authors: Jinsheng
authors: J
authors: Zeng
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects; D000071186:Beclin-1; D002544:Cerebral Infarction / Q000150:complications* / Q000473:pathology; D055785:Gene Knockdown Techniques; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009410:Nerve Degeneration / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013788:Thalamus / Q000187:drug effects / Q000473:pathology* / Q000648:ultrastructure; D014617:Vacuoles / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D016229:Amyloid beta-Peptides; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; C512829:Becn1 protein, rat; C025946:3-methyladenine; D000225:Adenine