Even though the disruption of axonal transport is an important pathophysiological factor in neurodegenerative diseases including Alzheimer's disease (AD), the relationship between disruption of axonal transport and pathogenesis of AD is poorly understood. Considering that α-tubulin acetylation is an important factor in axonal transport and that Aβ impairs mitochondrial axonal transport, we manipulated the level of α-tubulin acetylation in hippocampal neurons with Aβ cultured in a microfluidic system and examined its effect on mitochondrial axonal transport. We found that inhibiting histone deacetylase 6 (HDAC6), which deacetylates α-tubulin, significantly restored the velocity and motility of the mitochondria in both anterograde and retrograde axonal transports, which would be otherwise compromised by Aβ. The inhibition of HDAC6 also recovered the length of the mitochondria that had been shortened by Aβ to a normal level. These results suggest that the inhibition of HDAC6 significantly rescues hippocampal neurons from Aβ-induced impairment of mitochondrial axonal transport as well as mitochondrial length. The results presented in this paper identify HDAC6 as an important regulator of mitochondrial transport as well as elongation and, thus, a potential target whose pharmacological inhibition contributes to improving mitochondrial dynamics in Aβ treated neurons.

SummaryThe blood–brain barrier (BBB) is composed of brain capillary endothelial cells and has an important role in maintaining homeostasis of the brain separating the blood from the parenchyma of the central nervous system (CNS). It is widely known that disruption of the BBB occurs in various neurodegenerative diseases, including Alzheimer's disease (AD). Annexin A1 (ANXA1), an anti‐inflammatory messenger, is expressed in brain endothelial cells and regulates the BBB integrity. However, its role and mechanism for protecting BBB in AD have not been identified. We found that β‐Amyloid 1‐42 (Aβ42)‐induced BBB disruption was rescued by human recombinant ANXA1 (hrANXA1) in the murine brain endothelial cell line bEnd.3. Also, ANXA1 was decreased in the bEnd.3 cells, the capillaries of 5XFAD mice, and the human serum of patients with AD. To find out the mechanism by which ANXA1 recovers the BBB integrity in AD, the RhoA‐ROCK signaling pathway was examined in both Aβ42‐treated bEnd.3 cells and the capillaries of 5XFAD mice as RhoA was activated in both cases. RhoA inhibitors alleviated Aβ42‐induced BBB disruption and constitutively overexpressed RhoA‐GTP (active form of RhoA) attenuated the protective effect of ANXA1. When pericytes were cocultured with bEnd.3 cells, Aβ42‐induced RhoA activation of bEnd.3 cells was inhibited by the secretion of ANXA1 from pericytes. Taken together, our results suggest that ANXA1 restores Aβ42‐induced BBB disruption through inhibition of RhoA‐ROCK signaling pathway and we propose ANXA1 as a therapeutic reagent, protecting against the breakdown of the BBB in AD.

Alzheimer's disease (AD) is an age-related neurodegenerative disease. The most common pathological hallmarks are amyloid plaques and neurofibrillary tangles in the brain. In the brains of patients with AD, pathological tau is abnormally accumulated causing neuronal loss, synaptic dysfunction, and cognitive decline. We found a histone deacetylase 6 (HDAC6) inhibitor, CKD-504, changed the tau interactome dramatically to degrade pathological tau not only in AD animal model (ADLP APT ) brains containing both amyloid plaques and neurofibrillary tangles but also in AD patientderived brain organoids. Acetylated tau recruited chaperone proteins such as Hsp40, Hsp70, and Hsp110, and this complex bound to novel tau E3 ligases including UBE2O and RNF14. This complex degraded pathological tau through proteasomal pathway.We also identified the responsible acetylation sites on tau. These dramatic tau-interactome changes may result in tau degradation, leading to the recovery of synaptic pathology and cognitive decline in the ADLP APT mice.

CLIF-SOFA enables more accurate prediction of short-term mortality in patients with acutely decompensated alcoholic cirrhosis than other available scoring systems and is useful in predicting both 12-week mortality and the need for mechanical support after liver transplantation.

BackgroundReduction or inhibition of histone deacetylase 6 (HDAC6) has been shown to rescue memory in mouse models of Alzheimer’s disease (AD) and is recently being considered a possible therapeutic strategy. However, the restoring mechanism of HDAC6 inhibition has not been fully understood.Methods and resultsHere, we found that an anti-oxidant protein Peroxdiredoxin1 (Prx1), a substrate of HDAC6, malfunctions in Aβ treated cells, the brains of 5xFAD AD model mice and AD patients. Malfunctioning Prx1, caused by reduced Prx1 acetylation levels, was recovered by HDAC6 inhibition. Increasing acetylation levels of Prx1 by HDAC6 inhibition recovered elevated reactive oxygen species (ROS) levels, elevated Ca2+ levels and impaired mitochondrial axonal transport, sequentially, even in the presence of Aβ. Prx1 mutant studies on the K197 site for an acetylation mimic or silencing mutation support the results showing that HDAC6 inhibitor restores Aβ-induced disruption of ROS, Ca2+ and axonal transport.ConclusionsTaken together, increasing acetylation of Prx1 by HDAC6 inhibition has several beneficial effects in AD pathology. Here, we present the novel mechanism by which elevated acetylation of Prx1 rescues mitochondrial axonal transport impaired by Aβ. Therefore, our results suggest that modulation of Prx1 acetylation by HDAC6 inhibition has great therapeutic potential for AD and has further therapeutic possibilities for other neurodegenerative diseases as well.Electronic supplementary materialThe online version of this article (doi:10.1186/s13024-017-0164-1) contains supplementary material, which is available to authorized users.