Stable Expression of a Novel Fusion Peptide of Thioredoxin-1 and ABAD-Inhibiting Peptide Protects PC12 Cells from Intracellular Amyloid-Beta

Friend or enemy? Review of 17β-HSD10 and its role in human health or disease

17β-hydroxysteroid dehydrogenase (17β-HSD10) is a multifunctional human enzyme with important roles both as a structural component and also as a catalyst of many metabolic pathways. This mitochondrial enzyme has important functions in the metabolism, development and aging of the neural system, where it is involved in the homeostasis of neurosteroids, especially in regard to estradiol, changes in which make it an essential part of neurodegenerative pathology. These roles therefore, indicate that 17β-HSD10 may be a possible druggable target for neurodegenerative diseases including Alzheimer's disease (AD), and in hormone-dependent cancer. The objective of this review was to provide a summary about physiological functions and pathological roles of 17β-HSD10 and the modulators of its activity.

rAAV/ABAD-DP-6His attenuates oxidative stress-induced injury of PC12 cells

Our previous studies have revealed that amyloid β (Aβ)-binding alcohol dehydrogenase (ABAD) decoy peptide antagonizes Aβ42-induced neurotoxicity. However, whether it improves oxidative stress injury remains unclear. In this study, a recombinant adenovirus constitutively secreting and expressing Aβ-ABAD decoy peptide (rAAV/ABAD-DP-6His) was successfully constructed. Our results showed that rAAV/ABAD-DP-6His increased superoxide dismutase activity in hydrogen peroxide-induced oxidative stress-mediated injury of PC12 cells. Moreover, rAAV/ABAD-DP-6His decreased malondialdehyde content, intracellular Ca(2+) concentration, and the level of reactive oxygen species. rAAV/ABAD-DP-6His maintained the stability of the mitochondrial membrane potential. In addition, the ATP level remained constant, and apoptosis was reduced. Overall, the results indicate that rAAV/ABAD-DP-6His generates the fusion peptide, Aβ-ABAD decoy peptide, which effectively protects PC12 cells from oxidative stress injury induced by hydrogen peroxide, thus exerting neuroprotective effects.

Protein folding and misfolding in the neurodegenerative disorders: a review

Protein misfolding is an intrinsic aspect of normal folding within the complex cellular environment. Its effects are minimized in living system by the action of a range of protective mechanisms including molecular chaperones and quality control systems. According to the current growing research, protein misfolding is a recognized key feature of most neurodegenerative diseases. Extensive biochemical, neuropathological, and genetic evidence suggest that the cerebral accumulation of amyloid fibrils is the central event in the pathogenesis of neurodegenerative disorders. In the first part of this review we have discussed the general course of action of folding and misfolding of the proteins. Later part of this review gives an outline regarding the role of protein misfolding in the molecular and cellular mechanisms in the pathogenesis of Alzheimer's and Parkinson along with their treatment possibilities. Finally, we have mentioned about the recent findings in neurodegenerative diseases.

The novel amyloid-beta peptide aptamer inhibits intracellular amyloid-beta peptide toxicity

Amyloid β peptide binding alcohol dehydrogenase (ABAD) decoy peptide (DP) can competitively antagonize binding of amyloid β peptide to ABAD and inhibit the cytotoxic effects of amyloid β peptide. Based on peptide aptamers, the present study inserted ABAD-DP into the disulfide bond of human thioredoxin (TRX) using molecular cloning technique to construct a fusion gene that can express the TRX1-ABAD-DP-TRX2 aptamer. Moreover, adeno-associated virus was used to allow its stable expression. Immunofluorescent staining revealed the co-expression of the transduced fusion gene TRX1-ABAD-DP-TRX2 and amyloid β peptide in NIH-3T3 cells, indicating that the TRX1-ABAD-DP-TRX2 aptamer can bind amyloid β peptide within cells. In addition, cell morphology and MTT results suggested that TRX1-ABAD-DP-TRX2 attenuated amyloid β peptide-induced SH-SY5Y cell injury and improved cell viability. These findings confirmed the possibility of constructing TRX-based peptide aptamer using ABAD-DP. Moreover, TRX1-ABAD-DP-TRX2 inhibited the cytotoxic effect of amyloid β peptide.

Mitochondrial β-amyloid in Alzheimer's disease

It is well established that the intracellular accumulation of Aβ (amyloid β-peptide) is associated with AD (Alzheimer's disease) and that this accumulation is toxic to neurons. The precise mechanism by which this toxicity occurs is not well understood; however, identifying the causes of this toxicity is an essential step towards developing treatments for AD. One intracellular location where the accumulation of Aβ can have a major effect is within mitochondria, where mitochondrial proteins have been identified that act as binding sites for Aβ, and when binding occurs, a toxic response results. At one of these identified sites, an enzyme known as ABAD (amyloid-binding alcohol dehydrogenase), we have identified changes in gene expression in the brain cortex, following Aβ accumulation within mitochondria. Specifically, we have identified two proteins that are up-regulated not only in the brains of transgenic animal models of AD but also in those of human sufferers. The increased expression of these proteins demonstrates the complex and counteracting pathways that are activated in AD. Previous studies have identified approximate contact sites between ABAD and Aβ; on basis of these observations, we have shown that by using a modified peptide approach it is possible to reverse the expression of these two proteins in living transgenic animals and also to recover mitochondrial and behavioural deficits. This indicates that the ABAD–Aβ interaction is potentially an interesting target for therapeutic intervention. To explore this further we used a fluorescing substrate mimic to measure the activity of ABAD within living cells, and in addition we have identified chemical fragments that bind to ABAD, using a thermal shift assay.

The consequences of mitochondrial amyloid beta-peptide in Alzheimer's disease

The Abeta (amyloid-beta peptide) has long been associated with Alzheimer's disease, originally in the form of extracellular plaques. However, in the present paper we review the growing evidence for the role of soluble intracellular Abeta in the disease progression, with particular reference to Abeta found within the mitochondria. Once inside the cell, Abeta is able to interact with a number of targets, including the mitochondrial proteins ABAD (amyloid-binding alcohol dehydrogenase) and CypD (cyclophilin D), which is a component of the mitochondrial permeability transition pore. Interference with the normal functions of these proteins results in disruption of cell homoeostasis and ultimately cell death. The present review explores the possible mechanisms by which cell death occurs, considering the evidence presented on a molecular, cellular and in vivo level.