Articles
Publication Date: 2021
ACS Chemical Neuroscience (19487193)12(21)pp. 4037-4057
The aggregation of human alpha-synuclein (hαS) is pivotally implicated in the development of most types of synucleinopathies. Molecules that can inhibit or reverse the aggregation process of amyloidogenic proteins have potential therapeutic value. The anti-aggregating activity of multiple carotenoid compounds has been reported over the past decades against a growing list of amyloidogenic polypeptides. Here, we aimed to determine whether crocin, the main carotenoid glycoside component of saffron, would inhibit hαS aggregation or could disassemble its preformed fibrils. By employing a series of biochemical and biophysical techniques, crocin was exhibited to inhibit hαS fibrillation in a dose-dependent fashion by stabilizing very early aggregation intermediates in off-pathway non-toxic conformations with little β-sheet content. We also observed that crocin at high concentrations could efficiently destabilize mature fibrils and disassemble them into seeding-incompetent intermediates by altering their β-sheet conformation and reshaping their structure. Our atomistic molecular dynamics (MD) simulations demonstrated that crocin molecules bind to both the non amyloid-β component (NAC) region and C-terminal domain of hαS. These interactions could thereby stabilize the autoinhibitory conformation of the protein and prevent it from adopting aggregation-prone structures. MD simulations further suggested that ligand molecules prefer to reside longitudinally along the fibril axis onto the edges of the inter-protofilament interface where they establish hydrogen and hydrophobic bonds with steric zipper stabilizing residues. These interactions turned out to destabilize hαS fibrils by altering the interstrand twist angles, increasing the rigidity of the fibril core, and elevating its radius of gyration. Our findings suggest the potential pharmaceutical implication of crocin in synucleinopathies. ©
Publication Date: 2020
Preparative Biochemistry and Biotechnology (10826068)50(7)pp. 723-734
Herein, we describe a simple and efficient approach to produce recombinant human α-synuclein (hAS) with high purity from Escherichia coli (E. coli). The cDNA for hAS was inserted into plasmid pET32a and expressed in E. coli BL21 (DE3) with an N-terminal tag containing E. coli thioredoxin (trx), followed by a histidine hexapeptide, and a tobacco etch virus (TEV) protease cleavage site (trx-6His-TEV). The fusion protein, trx-hAS, was initially released by osmotic shock treatment from the host cells and subsequently purified using a nickel affinity chromatography. A TEV protease cleavage step was performed to liberate the target protein, hAS, from the fusion partner, trx. Finally, an additional nickel affinity chromatography was performed to further purify the digested product. The yield of this method is ∼25 mg of tag-less protein (with ∼99% purity) per liter of culture volume. Reverse phase HPLC (RP-HPLC) and electrospray ionization (ESI) mass spectrometry confirmed the purity and authenticity of the purified protein. Thioflavin T (ThT) fluorescence assay, transmission electron microscopy (TEM), and circular dichroism (CD) spectroscopy demonstrated that the purified proteins form fibrils. Our protocol not only provides a convenient procedure for preparing highly pure hAS, but also requires very little specialized laboratory techniques. © 2020 Taylor & Francis Group, LLC.
Publication Date: 2015
Tehran University Medical Journal (16831764)72(12)pp. 838-846
Background: Polymorphisms of the upstream transcription factor 1 (USF1) have been associated with familial combined hyperlipidemia (FCHL), type 2 diabetes and coronary heart diseases (CHD). In the current investigation, the association of USF1s2 variant of human USF1 gene with premature coronary artery disease (PCAD) was evaluated in a population from southern Iran. USF1s2 has the best potential as a functional variant.in the USF1 gene. Methods: In a case-control study USF1s2 variant of human USF1 gene was determined by polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) technique using BsiHKA I restriction enzyme for 186 women under 55 years of age and 135 men less than 50 years of age who underwent diagnostic coronary angiography in Saadi, Nemazee and Kowsar Hospitals of Shiraz, between July 2009 and March 2012. Data on the history of familial myocardial infarction or other heart diseases, hypertension, and smoking habit were collected by a simple questionnaire. Blood sugar level and serum lipid profile of all participants were also obtained by measuring the levels of fasting blood sugar (FBS), total cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL) and high-density lipoprotein cholesterol (HDL). Results: Frequencies of the major (G) and minor (A) alleles of usf1s2 gene variant were 0.74 and 0.26 in the whole population, respectively. Meanwhile, the prevalence of the minor allele was significantly higher in PCAD patients compared with control subjects. This difference remained significant even after adjustment for confounding parameters. Indeed, subjects with mutant homozygous genotype (AA) were about 5 times more likely to suffer from early-onset CAD than those with wild-type homozygous genotype (GG). Moreover, the baseline characteristics of the control subjects and patients were statistically similar for almost all parameters except for the number of male individuals; there was no significant difference among various genotypes in the patient group for any of these investigated variables. Conclusion: It appears that the usf1s2 variant in upstream transcription factor 1 gene is an independent predictor of premature coronary artery disease in our population and applies its effects without affecting blood sugar and lipid levels. © 2015, Tehran University of Medical Sciences. All rights reserved.
