• BMB Reports
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• 제52권6호
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• pp.349-359
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• 2019

After the first research declaring the generation of human induced pluripotent stem cells (hiPSCs) in 2007, several attempts have been made to model neurodegenerative disease in vitro during the past decade. Parkinson's disease (PD) is the second most common neurodegenerative disorder, which is mainly characterized by motor dysfunction. The formation of unique and filamentous inclusion bodies called Lewy bodies (LBs) is the hallmark of both PD and dementia with LBs. The key pathology in PD is generally considered to be the alpha-synuclein (${\alpha}$-syn) accumulation, although it is still controversial whether this protein aggregation is a cause or consequence of neurodegeneration. In the present work, the recently published researches which recapitulated the ${\alpha}$-syn aggregation phenomena in sporadic and familial PD hiPSC models were reviewed. Furthermore, the advantages and potentials of using patient-derived PD hiPSC with focus on ${\alpha}$-syn aggregation have been discussed.

• Journal of Microbiology and Biotechnology
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• 제9권3호
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• pp.276-281
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• 1999

In order to determine the functional region of the antifungal protein (AFP) isolated from Aspergillus giganteus responsible for growth inhibitory activity and the promotion of phospholipid vesicle aggregation, overlapping peptides covering the complete sequence of AFP were synthesized. The antibiotic activity against bacterial, fungal, and tumor cells, and the vesicle-aggregation activity of the synthetic peptides were investigated. The AFP functional sequence responsible for antibiotic and vesicle-aggregation activity was determined to be located within the region between AFP residues 19 to 32. AFP (19-32) exhibited an a-helical conformation in a cell membrane-like environment. AFP (19-32) displayed potent antibiotic activity against bacterial, fungal, and tumor cells without peptide toxicity as indicated by hemolysis. Accordingly, AFP (19-32) could be used as a good model for the design of effective antibiotic agents with powerful antibiotic activity yet without any cytotoxic effects against the host organism.

• Journal of Applied Biological Chemistry
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• 제65권1호
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• pp.57-62
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• 2022

혈소판의 과도한 활성화 및 응집은 심혈관계 질환의 주요원인이 된다. 따라서, 혈소판 활성화 및 응집을 억제하는 것은 심혈관계 질환을 예방하고 치료하는데 있어서 매력적인 치료 표적으로 여겨진다. 특히, 혈관 내피세포에서 분비되는 collagen에 의한 강력한 혈소판 활성화와 응집이 혈관질환에서 특징적이다. Artesunate는 Artemisia 또는 Scopolia 속 식물의 뿌리에서 추출한 화합물이며, 항암 및 알츠하이머 병 분야에서 효과가 있다고 보고된 바 있다. 그러나, artesunate가 collagen 유도의 혈소판 활성화와 응집에 미치는 영향과 그 기전에 대해서는 규명된 바가 없다. 본 연구에서는 collagen이 유도하는 사람 혈소판 응집에 있어 artesunate이 미치는 영향을 확인하였고, artesunate의 작용 기전을 명확히 하였다. Artesunate은 혈소판가 활성화 될 때 신호 전달 과정에 작용한다고 알려진 인단백질인 PI3K/Akt 및 MAPK의 인산화를 억제하였다. 또한, artesunate는 TXA2 생성을 감소시켰고, ATP 및 serotonin 방출 등의 혈소판 내 과립 분비를 감소시켰다. 그 결과, artesunate는 혈관 내피세포에서 분비되는 강력한 응집 유도 물질인 collagen으로 유도된 혈소판 응집을 106.41 μM의 IC₅₀로 강력하게 억제하였다. 이 결과들을 통해, artesunate가 혈관 손상을 통해 일어나는 사람 혈소판의 활성화 및 응집을 억제하는 데 유효한 항혈전 물질로 가치가 있음을 제안한다.

• BMB Reports
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• 제38권3호
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• pp.259-265
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• 2005

Proteins must fold into their correct three-dimensional conformation in order to attain their biological function. Conversely, protein aggregation and misfolding are primary contributors to many devastating human diseases, such as prion-mediated infections, Alzheimer's disease, type II diabetes and cystic fibrosis. While the native conformation of a polypeptide is encoded within its primary amino acid sequence and is sufficient for protein folding in vitro, the situation in vivo is more complex. Inside the cell, proteins are synthesized or folded continuously; a process that is greatly assisted by molecular chaperones. Molecular chaperones re a group of structurally diverse and mechanistically distinct proteins that either promote folding or prevent the aggregation of other proteins. With our increasing understanding of the proteome, it is becoming clear that the number of proteins that can be classified as molecular chaperones is increasing steadily. Many of these proteins have novel but essential cellular functions that differ from that of more 'conventional' chaperones, such as Hsp70 and the GroE system. This review focuses on the emerging role of molecular chaperones in protein quality control, i.e. the mechanism that rids the cell of misfolded or incompletely synthesized polypeptides that otherwise would interfere with normal cellular function.

• BMB Reports
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• 제55권7호
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• pp.323-335
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• 2022

Together with neuronal loss, the existence of insoluble inclusions of alpha-synuclein (α-syn) in the brain is widely accepted as a hallmark of synucleinopathies including Parkinson's disease (PD), multiple system atrophy, and dementia with Lewy body. Because the α-syn aggregates are deeply involved in the pathogenesis, there have been many attempts to demonstrate the mechanism of the aggregation and its potential causative factors including post-translational modifications (PTMs). Although no concrete conclusions have been made based on the previous study results, growing evidence suggests that modifications such as phosphorylation and ubiquitination can alter α-syn characteristics to have certain effects on the aggregation process in PD; either facilitating or inhibiting fibrillization. In the present work, we reviewed studies showing the significant impacts of PTMs on α-syn aggregation. Furthermore, the PTMs modulating α-syn aggregation-induced cell death have been discussed.

• 대한의생명과학회지
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• 제9권4호
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• pp.203-207
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• 2003

Protein aggregation could be problematic as causes of diseases and hindrance in the production of useful recombinant proteins. Aggregation of mutant tryptophan synthase $\alpha$-subunits was examined by treatment with urea and at high temperature. Large amorphous aggregate seemed to appear by heat treatment, while more various aggregates in size were formed by treatment with urea at low concentration. The result indicates that different aggregate in size could be formed depending on the treatment condition, suggesting different mechanisms underlying aggregation processes.

• Journal of Microbiology and Biotechnology
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• 제21권10호
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• pp.1053-1056
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• 2011

Optimal conditions for a high cell density fermentation were investigated in a recombinant Escherichia coli producing salmosin, a platelet aggregation inhibitor. The optimized carbon and nitrogen sources were glycerol 10 g/l, yeast extract 30 g/l, and bacto-tryptone 10 g/l, yielding the dry cell weight (DCW) of 10.61 g/l in a 500 ml flask culture. The late-stage induction with 1% L-arabinose in a 5 l jar fermentor showed the highest DCW of 65.70 g/l after 27 h of the fed-batch fermentation. Around 2,200 mg/l of the protein was expressed as an inclusion body that was then refolded to obtain the active salmosin of 96 mg/l. We also confirmed the inhibitory activity against platelet aggregation of the active salmosin from the high cell density fermentation.

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.77-80
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• 2007

As neurofilament proteins are major cytoskeletal components of neuron, abnormality of neurofilament is proposed in brain with neurodegenerative disorders such as Parkinson's disease (PD). Since oxidative stress might play a critical role in altering normal brain proteins, we investigated the oxidative modification of neurofilament-L (NF-L) induced by the reaction of cytochrome c with H2O2. When NF-L was incubated with cytochrome c and H2O2, the protein aggregation was increased in cytochrome c and H2O2 concentrationsdependent manner. Radical scavengers, azide, formate and N-acetyl cysteine, prevented the aggregation of NFL induced by the cytochrome c/H2O2 system. The formations of carbonyl group and dityrosine were obtained in cytochrome c/H2O2-mediated NF-L aggregates. Iron specific chelator, desferoxamine, prevented the cytochrome c/H2O2 system-mediated NF-L aggregation. These results suggest that the cytochrome c/H2O2 system may be related to abnormal aggregation of NF-L which may be involved in the pathogenesis of PD and related disorders.

• Journal of Microbiology and Biotechnology
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• 제8권6호
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• pp.663-668
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• 1998

Several neurodegenerative diseases such as Huntington's disease, dentatorubralpallidoluysian atrophy, spinobulbar muscular atrophy, Machado-Joseph disease, and spinocerebellar ataxias type 1 are associated with the aggregation of expanded glutamine repeats within their proteins. Generally, in clinically affected individuals, the expansion of the polyglutamine sequences is beyond 40 residues. To address the length of polyglutamine that forms aggregation, we have constructed plasmids encoding glutathione S-transferase (GST) Machado-Joseph disease gene fusion proteins containing polyglutamine and investigated the formation of aggregates in E. coli. Surprisingly, even $(Gin)_8$, in the normal range as well as $(Gin)_{65}$ in the pathogenic range enhanced the formation of insoluble protein aggregates, whereas $(Ser)_8$, and $(Aia)_8$, did not form aggregates. Our results indicate that the formation of protein aggregates in GST-polyglutamine proteins is specifically mediated by the polyglutamine repeat sequence within their protein structure. Our study may contribute to the understanding of the molecular mechanism of the formation of protein aggregates in neurodegenerative disorders and the development of preventative strategies.

• 한국자기공명학회논문지
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• 제15권2호
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• pp.175-186
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• 2011

Amyloid fibrils have long been known to be the well known ${\alpha}$-helix to ${\beta}$-sheet transition characterizing the conversion of cellular to scrapie forms of the prion protein. A very short sequence of Yeast prion-like protein, GNNQQNY (SupN), is responsible for aggregation that induces diseases. KSI-fused tandem repeats of SupN vector are constructed and used to express SupN peptide in Escherichia coli (E.Coli). A method for a production, purification, and cleavage of tandem repeats of recombinant isotopically enriched SupN in E. coli is described. This method yields as much as 20 mg/L of isotope-enriched fusion proteins in minimal media. Synthetic SupN peptides and $^{13}C$ Gly labeled SupN peptides are studied by Congo Red staining, Birefringence and transmission electron microscopy to characterize amyloid fibril formation. To get a better understanding of aggregation-structure relationship of 7 residues of Yeast prion-like protein, the change of a conformational structure will be studied by $^{13}C$ solid-state nmr spectroscopy as powder of both amorphous and fibrillar forms.