• Bulletin of the Korean Chemical Society
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• v.32 no.10
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• pp.3553-3554
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• 2011

• BMB Reports
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• v.28 no.6
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• pp.546-551
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• 1995

The conformation studies of myelin P2 protein and two of its major peptides were carried out using circular dichroism and fluorescence spectroscopy in water and in lipid environments. Significant conformational changes occur when the protein or peptides were bound to gangliosides. Similar effects were also found in trifluoroethanol solutions. The conformational features of P2 protein and its major peptides were discussed in relation to the environmental changes and the disease-inducing effects.

• BMB Reports
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• v.38 no.3
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• pp.275-280
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• 2005

For most of proteins to be active, they need well-defined three-dimensional structures alone or in complex. Folding is a process through which newly synthesized proteins get to the native state. Protein folding inside cells is assisted by various chaperones and folding factors, and misfolded proteins are eliminated by the ubiquitin-proteasome degradation system to ensure high fidelity of protein expression. Under certain circumstances, misfolded proteins escape the degradation process, yielding to deposit of protein aggregates such as loop-sheet polymer and amyloid fibril. Diseases characterized by insoluble deposits of proteins have been recognized for long time and are grouped as conformational diseases. Study of protein folding mechanism is required for better understanding of the molecular pathway of such conformational diseases.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.14-23
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• 2015

Alzheimer's disease is one of the most common types of degenerative dementia. As a considerable cause of Alzheimer's disease, neurotoxic plaques composed of 39 to 42 residue-long amyloid beta($A{\beta}$) fibrils have been found in the patient's brain in large quantity. A previous study found that erythrosine B (ER), a red color food dye approved by FDA, inhibits the formation of amyloid beta fibril structures. Here, in an attempt to elucidate the inhibition mechanism, we performed molecular dynamics simulations to demonstrate the conformational change of $A{\beta}40$ induced by 2 ERs in atomistic detail. During the simulation, the ERs bound to the surfaces of both N-terminus and C-terminus regions of $A{\beta}40$ rapidly. The observed stacking of the ERs and the aromatic side chains near the N-terminus region suggests a possible inhibition mechanism in which disturbing the inter-chain stacking of PHEs destabilizes beta-sheet enriched in amyloid beta fibrils. The bound ERs block water molecules and thereby help stabilizing alpha helical structure at the main chain of C-terminus and interrupt the formation of the salt-bridge ASP23-LYS28 at the same time. Our findings can help better understanding of the current and upcoming treatment studies for Alzheimer's disease by suggesting inhibition mechanism of ER on the conformational transition of $A{\beta}40$ at the molecular level.

• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1225-1228
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• 2005

C-terminal fragments of APP (APP-CTs), that contain A$\beta$ sequence, are found in neurotic plaques, neurofibrillary tangles and the cytosol of lymphoblastoid cells obtained from AD patients. CT26, Thr639-Asp664 (TVIVITLVMLKKKQYTSIHH GVVEVD) includes not only the transmembrane domain but also the cytoplasmic domain of APP. This sequence is produced from cleavage of APP by caspase and $\gamma$-secretase. In this study, the solution structure of CT26 was investigated using NMR spectroscopy and circular dichroism (CD) spectropolarimeter in various membrane-mimicking environments. According to CD spectra and the tertiary structure of CT26 determined in TFE-containing aqueous solution, CT26 has an α-helical structure from $Val^{2}\;to\;Lys^{11}$ in TFE-containing aqueous solution. However, according to CD data, CT26 adopts a $\beta$-sheet structure in the SDS micelles and DPC micelles. This result implies that CT26 may have a conformational transition between $\alpha$-helix and $\beta$-sheet structure. This study may provide an insight into the conformational basis of the pathological activity of the C-terminal fragments of APP in the model membrane.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1059-1070
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• 2007

Prion diseases, often called transmissible spongiform encephalopathies (TSEs), are infectious diseases that accompany neurological dysfunctions in many mammalian hosts. Prion diseases include Creutzfeldt-Jakob disease (CJD) in humans, bovine spongiform encephalopathy (BSE, "mad cow disease") in cattle, scrapie in sheep, and chronic wasting disease (CWD) in deer and elks. The cause of these fatal diseases is a proteinaceous pathogen termed prion that lacks functional nucleic acids. As demonstrated in the BSE outbreak and its transmission to humans, the onset of disease is not limited to a certain species but can be transmissible from one host species to another. Such a striking nature of prions has generated huge concerns in public health and attracted serious attention in the scientific communities. To date, the potential transmission of prions to humans via foodborne infection and iatrogenic routes has not been alleviated. Rather, the possible transmission of human to human or cervids to human aggravates the terrifying situation across the globe. In this review, basic features about prion diseases including clinical and pathological characteristics, etiology, and transmission of diseases are described. Based on recently accumulated evidences, the molecular and biochemical aspects of prions, with an emphasis on the molecular interactions involved in prion conversion that is critical during prion replication and pathogenesis, are also addressed.

• Molecules and Cells
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• v.27 no.6
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• pp.621-627
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• 2009

Spinocerebellar ataxia type 1 (SCA1) is an autosomal-dominant neurodegenerative disorder characterized by ataxia and progressive motor deterioration. SCA1 is associated with an elongated polyglutamine tract in ataxin-1, the SCA1 gene product. As summarized in this review, recent studies have clarified the molecular mechanisms of SCA1 pathogenesis and provided direction for future therapeutic approaches. The nucleus is the subcellular site where misfolded mutant ataxin-1 acts to cause SCA1 disease in the cerebellum. The role of these nuclear aggregates is the subject of intensive study. Additional proteins have been identified, whose conformational alterations occurring through interactions with the polyglutamine tract itself or non-polyglutamine regions in ataxin-1 are the cause of SCA-1 cytotoxicity. Therapeutic hope comes from the observations concerning the reduction of nuclear aggregation and alleviation of the pathogenic phenotype by the application of potent inhibitors and RNA interference.

• Biomedical Science Letters
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• v.21 no.1
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• pp.1-8
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• 2015

Alzheimer's disease is a common form of dementia occurring among the elderly population and can be identified by symptoms such as cognition impairments, memory loss and neuronal dysfunction. Alzheimer's disease was found to be caused by the deposition of $\beta$-amyloid plaques and neurofibrillary tangles. In addition, mutation in the APP (Amyloid precursor protein), Presenilin 1 (PSEN1) and Presenilin 2 (PSEN2) genes were also found to contribute to Alzheimer's disease. Since the potential conformational diagnosis of Alzheimer's disease requires histopathological tests on brain through autopsy, potential early diagnosis still remains challenging. In recent years, several researches have proposed the use of biomarkers for early diagnosis. In cerebrospinal fluid (CSF), $\beta$-amyloid(1-42), phosphorylated-tau and total tau were suggested to be effective biomarkers for Alzheimer's disease diagnosis. However, a single biomarker might not be sufficient for potential diagnosis of Alzheimer's disease. Thus, the use of RNA interference (RNAi) through microRNAs (miRNAs) has been proposed by several researchers for simultaneous analysis of several biomarkers using microarray technology. These miRNA based biomarkers can be analysed from both blood and CSF, but miRNAs from blood are advantageous over CSF as they are non-invasive and simple for collection. Moreover, the RNAi based therapeutics by siRNA (short interference RNA) or shRNA (short hairpin RNA) have also been proposed to be effective in the treatment of Alzheimer's disease. This review describes the promising application of RNAi technology in therapeutics and as a biomarker for both Alzheimer's disease diagnosis and treatment.

• Biomedical Science Letters
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• v.27 no.4
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• pp.270-276
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• 2021

Physiological agents trigger a signaling process called "inside-out signaling" and activated platelets promote adhesion, granule release, and conformational changes of glycoprotein IIb/IIIa (αIIb/β₃). Activated αIIb/β₃ interacts with fibrinogen and initiates a second signaling step called "external signaling". These two signaling pathways can cause hemostasis or thrombosis, and thrombosis is a possible medical problem in arterial and venous vessels, and platelet-mediated thrombosis is a major cause of cardiovascular disease (CVD). Therefore, modulating platelet activity is important for platelet-mediated thrombosis and cardiovascular disease. Esculetin is a coumarin-based physiologically active 6,7-dihydroxy derivative known to have pharmacological activity against obesity, diabetes, renal failure and CVD. Although some studies have confirmed the effects of esculetin in human platelet activation and experimental mouse models, it is not clear how esculetin has antiplatelet and antithrombotic effects. We confirmed the effect and mechanism of action of escultein on human platelets induced by collagen. As a result, esculetin decreased Ca²⁺ recruitment through upregulation of inositol 1, 4, 5-triphosphate receptor. In addition, esculetin upregulates cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP)-dependent pathways and inhibits fibrinogen binding and thrombus contraction. Our results demonstrate the antiplatelet effect and antithrombotic effect of esculetin in human platelets. Therefore, we suggest that esculetin could be a potential phytochemical for the prevention of thrombus-mediated CVD.

• Journal of Microbiology and Biotechnology
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• v.23 no.3
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• pp.279-288
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• 2013

Phosphorylation and dephosphorylation of proteins trigger many critical events involved in cellular response, such as regulation of enzymatic activity, protein conformational change, protein-protein interaction, and cellular localization. Any malfunction of protein phosphorylation leads to a diseased state such as diabetes, cancer, and even neurodegenerative diseases. In order to comprehend the molecular view of the complex biological processes of these diseases in depth, very sensitive and detailed analytical methods are necessary for identification of the phosphorylated residues in a protein. As part of these efforts, phosphoproteomics has been developed and applied for the elucidation of neurodegenerative diseases. In this review, we present a brief summary of phosphoproteomics approaches that are now routinely used in biomedical research, and describe the biomedical application of phosphoproteomics especially in Alzheimer's and other neurodegenerative diseases.