Crafting of Neuroprotective Octapeptide from Taxol-Binding Pocket of β‑Tubulin

Microtubules play a crucial role in maintaining the shape and function of neurons. During progression of Alzheimer’s disease (AD), severe destabilization of microtubules occurs, which leads to the permanent disruption of signal transduction processes and memory loss. Thus, microtubule stabilization is one of the key requirements for the treatment of AD. Taxol, a microtubule stabilizing anticancer drug, has been considered as a potential anti-AD drug but was never tested in AD patients, likely because of its’ toxic nature and poor brain exposure. However, other microtubule-targeting agents such as epothilone D (BMS-241027) and TPI-287 (abeotaxane) and NAP peptide (davunetide) have entered in AD clinical programs. Therefore, the taxol binding pocket of tubulin could be a potential site for designing of mild and noncytotoxic microtubule stabilizing molecules. Here, we adopted an innovative strategy for the development of a peptide based microtubule stabilizer, considering the taxol binding pocket of β-tubulin, by using alanine scanning mutagenesis technique. This approach lead us to a potential octapeptide, which strongly binds to the taxol pocket of β-tubulin, serves as an excellent microtubule stabilizer, increases the expression of acetylated tubulin, and acts as an Aβ aggregation inhibitor and neuroprotective agent. Further, results revealed that this peptide is nontoxic against both PC12 derived neurons and primary cortical neurons. We believe that our strategy and discovery of peptide-based microtubule stabilizer will open the door for the development of potential anti-AD therapeutics in near future

Genesis of Neuroprotective Peptoid from Aβ30–34 Inhibits Aβ Aggregation and AChE Activity

Aβ peptide and hyper-phosphorylated microtubule associated protein (Tau) aggregation causes severe damage to both the neuron membrane and key signal processing microfilament (microtubule) in Alzheimer’s disease (AD) brains. To date, the key challenge is to develop nontoxic, proteolytically stable amyloid inhibitors, which can simultaneously target multiple pathways involved in AD. Various attempts have been made in this direction; however, clinical outcomes of those attempts have been reported to be poor. Thus, we choose development of peptoid (N-substituted glycine oligomers)-based leads as potential AD therapeutics, which are easy to synthesize, found to be proteolytically stable, and exhibit excellent bioavailability. In this paper, we have designed and synthesized a new short peptoid for amyloid inhibition from 30−34 hydrophobic pocket of amyloid beta (Aβ) peptide. The peptoid selectively binds with 17–21 hydrophobic region of Aβ and inhibits Aβ fibril formation. Various <i>in vitro</i> assays suggested that our AI peptoid binds with tubulin/microtubule and promotes its polymerization and stability. This peptoid also inhibits AChE-induced Aβ fibril formation and provides significant neuroprotection against toxicity generated by nerve growth factor (NGF) deprived neurons derived from rat adrenal pheochromocytoma (PC12) cell line. Moreover, this peptoid shows serum stability and is noncytotoxic to primary rat cortical neurons