Inhibition of excessive autophagy and mitophagy mediates neuroprotective effects of URB597 against chronic cerebral hypoperfusion

Abstract

URB597 (URB) has therapeutic potential for treating chronic cerebral hypoperfusion (CCH)-induced neuronal death. The present study investigated the protective effects of URB on autopahgy and mitophagy in a CCH model as well as the underlying mechanisms. The ultrastructural changes were examined by electron microscopy. The mitochondrial membrane potential was assessed by immunofluorescence. The expressions of autophagy-related proteins (beclin-1, p62, and LC3), lysosome-related proteins (CTSD and LAMP1), and mitophagy-related proteins (BNIP3, cyt C and parkin) were evaluated by western blotting, and the interaction of beclin-1 and Bcl-2 were determined by immunoprecipitation. CCH significantly decreased the protein expression of p62, CTSD, and LAMP1 and increased the protein expression of beclin-1, parkin, and BNIP3, the LC3-II to LC3-I ratio, and the release of cyt C from mitochondria to cytoplasm. Furthermore, CCH induced the accumulation of ubiquitinated proteins in PSDs. However, URB significantly reversed these results. Besides, URB significantly inhibited the beclin-1 from beclin-1/Bcl-2 complex to whole-cell lysates. The above results indicate that URB could inhibit impaired autophagy degradation and the disruption of beclin-1/Bcl-2 complex and subsequently cut off BNIP3-cyt C- and parkin-required mitophagy, finally preventing the abnormal excessive autophagy and mitophagy. These findings provide new insights that URB is a promising agent for therapeutic management of CCH.

URB597 protects against NLRP3 inflammasome activation by inhibiting autophagy dysfunction in a rat model of chronic cerebral hypoperfusion

“…In our previous study [7][8][9][10][11], we found that CCH may contribute to neuronal apoptosis, cognitive impairment, chronic neuroinflammatory responses and abnormal excessive autophagy in the frontal cortex and hippocampus of rats, resulting in cerebral ischemic damage. The fatty acid amide hydrolase inhibitor URB597 (URB) could be a candidate for alleviating chronic intracranial ischemic injury, as it could offer increased selective protection with less risk of the undesirable side effects that have been observed with cannabinoid receptor agonists capable of activating all accessible receptors indiscriminately [7][8][9][10][11]. Thus, we believe that URB might be a promising therapeutic agent for the treatment and management of CCH.…”

“…and 3-MA [3 μg/day, intracerebroventricular (i.c.v.) injection] dosages were selected based on previous studies [11,[23][24][25]. For baseline balance, all experimental rats received the intracerebroventricular catheter implantation.…”

“…Briefly, according to our previous study [11], coronal slices in the CA1 hippocampal area were cut to a thickness of 1 mm and postfixed with 2.5% glutaraldehyde overnight at 4°C. Then, these slices were washed with 0.1 mol/L PBS three times, and were postfixed in 1% osmium tetroxide for 2 h at 4°C.…”

“…A substantial amount of evidence indicates that chronic cerebral hypoperfusion (CCH), a state of chronic cerebral blood flow reduction, is associated with several cerebrovascular and neurodegenerative disorders including Alzheimer's disease (AD), carotid stenosis/occlusion, cerebral arteriovenous malformation, dural arteriovenous fistula, moyamoya disease and cerebral small vessel disease [1][2][3][4][5][6]. In our previous study [7][8][9][10][11], we found that CCH may contribute to neuronal apoptosis, cognitive impairment, chronic neuroinflammatory responses and abnormal excessive autophagy in the frontal cortex and hippocampus of rats, resulting in cerebral ischemic damage. The fatty acid amide hydrolase inhibitor URB597 (URB) could be a candidate for alleviating chronic intracranial ischemic injury, as it could offer increased selective protection with less risk of the undesirable side effects that have been observed with cannabinoid receptor agonists capable of activating all accessible receptors indiscriminately [7][8][9][10][11].…”

Exaggerated mitophagy: a weapon of striatal destruction in the brain?

“…CCH is found in many cerebrovascular diseases, including AD. Excessive BNIP3-cyt C-and parkin-mediated mitophagy was found in CCH, and the fatty acid amide hydrolase inhibitor URB597 (URB) promotes neuroprotection by inhibiting abnormal excessive autophagy as well as mitophagy [24]. Intriguingly, excessive mitophagy was found in a genetic mouse model of HD [25].…”