Inhibition study on insulin fibrillation and cytotoxicity by paclitaxel

Abstract

Alzheimer, a neurodegenerative disease, and a large variety of pathologic conditions are associated with a form of protein aggregation known as amyloid fibrils. Since fibrils and prefibrillar intermediates are cytotoxic, numerous attempts have been made to inhibit fibrillation process as a therapeutic strategy. Peptides, surfactants and aromatic small molecules have been used as fibrillation inhibitors. Here we studied the effects of paclitaxel, a polyphenol with a high tendency for interaction with proteins, on fibrillation of insulin as a model protein. The effects of paclitaxel on insulin fibrillation were determined by Thioflavin T fluorescence, Congo red absorbance, circular dichroism and atomic force microscopy. These studies indicated that paclitaxel considerably hindered nucleation, and therefore, fibrillation of insulin in a dose-dependant manner. The isothermal titration calorimetry studies showed that the interaction between paclitaxel and insulin was spontaneous. In addition, the van der Waal's interactions and hydrogen bonds were prominent forces contributing to this interaction. Computational results using molecular dynamic simulations and docking studies revealed that paclitaxel diminished the polarity of insulin dimer and electrostatic interactions by increasing the hydrophobicity of its dimer state. Furthermore, paclitaxel reduced disrupting effects of insulin fibrils on PC12 cell's neurite outgrowth and complexity, and enhanced their survival.

A Small Molecule Impedes Insulin Fibrillation: Another New Role of Phenothiazine Derivatives

“…By interacting with the insulin monomers, MB inhibits insulin oligomerization. After comparing our CD experimental results with the results obtained by Wang et al., Kachooei et al., and Banerjee et al., we found that MB retained the secondary structure of insulin with more efficiency.…”

Effects of several quinones on insulin aggregation

“…Insulin amyloidosis was commonly found at the site of repeated insulin injection in diabetic patients as well as in the clinic formulations891011. Different from the natively unstructured amyloidogenic proteins such as islet amyloid polypeptide, amyloid-β and α-synuclein121314, insulin belongs to the category of natively structured amyloidogenic proteins, such as prion and lysozyme151617, and is also commonly used as a classical model to probe the mechanisms of protein fibrillation since insulin amyloids share the same typical cross-β structure as the mature fibrils of the disease relevant amyloids41819, as well as an amyloid model system for studying aggregation inhibitors2021.…”

Curcumin Protects β-Lactoglobulin Fibril Formation and Fibril-Induced Neurotoxicity in PC12Cells

“…It is believed that aggregated/ fibrillar amyloid proteins are toxic to neurons and neuron-like cells [ 47 – 50 ]. The PC-12 cells line as a useful model for neurobiological studies have been employed in studying differentiation, survival and apoptosis [ 51 , 52 ]. Here protein fibrils were employed as a neurotoxicant, and the viability of PC12 cells was measured after incubation with native β-Lgand β-Lgfibrilsobtained in the absence or presence of curcumin, Pb ions and AFM1 using an MTT assay.…”