RNA interference-mediated downregulation of Beclin1 attenuates cerebral ischemic injury in rats

Abstract

Aim: To test the role of the Beclin 1-dependent autophagy pathway in brain damage during cerebral ischemia. Methods: Focal cerebral ischemia was established in rats using a middle cerebral artery occlusion (MCAO) model. A lentiviral vectorassociated RNA interference (RNAi) system was stereotaxically injected into the ipsilateral lateral ventricle to reduce Beclin1 expression. We measured the ipsilateral infarct volume, autophagosome formation, neurogenesis and apoptosis, all of which could be modulated by Beclin1 RNAi. Results: On the 14th day after MCAO, Beclin1 downregulation by RNAi increased the population of neural progenitor cells (BrdU + -DCX + ), newborn immature cells (BrdU + -Tuj-1 + ) and mature neurons (BrdU + -MAP-2 + ), and reduced the apoptosis of immature neurons (caspase-3 + -DCX + and caspase-3 + -Tuj-1 + ) surrounding the ischemic core of the ipsilateral hemisphere. Furthermore, RNAi-mediated downregulation of Beclin1 decreased infarct volume and inhibited histological injury and neurological deficits. Conclusion: RNAi-mediated downregulation of Beclin1 improves outcomes after transient MCAO.

Death and survival of neuronal and astrocytic cells in ischemic brain injury: a role of autophagy

“…The identification of autophagy (Atg) genes involved in specific ubiquitinlike conjugation reactions that are essential for the extension of autophagic membranes has revolutionized the field, allowing for the development of specific markers for autophagic vacuole formation and maturation and providing molecular genetic tools for knocking out or knocking down essential Atg gene products. Recently, evidence on the genetic level showing that ribonucleic acid interference (RNAi)-mediated downregulation of Beclin1 decreases infarct volume and inhibits histological injury and neurological deficits induced by focal cerebral ischemia [61] supports the present conclusion.…”

Inhibition of Autophagy Contributes to Melatonin-Mediated Neuroprotection Against Transient Focal Cerebral Ischemia in Rats

“…It is well known that autophagy is involved in the regulation of neuronal death following cerebral ischemia (2,3,10). During autophagy, cytoplasmic components are sequestered into double-membrane vesicles called autophagosomes, which fuse with lysosomes and are degraded by lysosomal hydrolases.…”

“…Inhibition of autophagy with chemical inhibitors (i.e., 3-MA, bafilomycin A1) reduced neuronal injury in focal ischemia (9). Our previous report revealed that lentiviralmediated knockdown of beclin-1 improved outcome of cerebral ischemic injury, with evidence for increased (10). On the basis of such evidences, many researchers accept that autophagy is a major mediator of cell death in cerebral ischemia (2).…”

“…One is the dysregulation of Class I phosphatidylinositol 3-kinase (PI3K), which in turn activates the Akt/protein kinase B (PKB) kinase pathway. The other is the binding of Beclin-1 (Atg6 or BECN1) to Class III PI3Ks that regulates autophagosome formation (10,22). Autophagy falls under negative regulation by a signaling pathway involving Class I PI3K/Akt, while Beclin-1 forms a protein complex with a Class III PI3Ks to promote autophagic vacuole formation (23,24).…”

Ischemic Stroke Mechanisms, Prevention, and Treatment: The Anesthesiologist’s Perspective

“…Whether autophagy is a driver of cell death in ischemia is still not clarified. Some experimental evidence suggests that reducing autophagy early after infarction can attenuate injury progression (71,(74)(75)(76). Conversely, other studies indicate that promoting autophagy may induce cells to undergo apoptotic rather than necrotic cell death, leading to reduced lesion sizes (71,77,78).…”