• Biomolecules & Therapeutics
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• v.27 no.6
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• pp.530-539
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• 2019

Brain aging is an inevitable process characterized by structural and functional changes and is a major risk factor for neurodegenerative diseases. Most brain aging studies are focused on neurons and less on astrocytes which are the most abundant cells in the brain known to be in charge of various functions including the maintenance of brain physical formation, ion homeostasis, and secretion of various extracellular matrix proteins. Altered mitochondrial dynamics, defective mitophagy or mitochondrial damages are causative factors of mitochondrial dysfunction, which is linked to age-related disorders. Etoposide is an anti-cancer reagent which can induce DNA stress and cellular senescence of cancer cell lines. In this study, we investigated whether etoposide induces senescence and functional alterations in cultured rat astrocytes. Senescence-associated ${\beta}$-galactosidase (SA-${\beta}$-gal) activity was used as a cellular senescence marker. The results indicated that etoposide-treated astrocytes showed cellular senescence phenotypes including increased SA-${\beta}$-gal-positive cells number, increased nuclear size and increased senescence-associated secretory phenotypes (SASP) such as IL-6. We also observed a decreased expression of cell cycle markers, including PhosphoHistone H3/Histone H3 and CDK2, and dysregulation of cellular functions based on wound-healing, neuronal protection, and phagocytosis assays. Finally, mitochondrial dysfunction was noted through the determination of mitochondrial membrane potential using tetramethylrhodamine methyl ester (TMRM) and the measurement of mitochondrial oxygen consumption rate (OCR). These data suggest that etoposide can induce cellular senescence and mitochondrial dysfunction in astrocytes which may have implications in brain aging and neurodegenerative conditions.

• Journal of Life Science
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• v.29 no.7
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• pp.817-823
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• 2019

Immune system provides defense integrity of body against external invaders. In order to accomplish the important defending role immune system is composed of many different components which are regenerated continuously during lifespan. The key components are professional killing cells such as macrophage, neutrophil, natural killer cell, and cytotoxic T cell and professional blocking molecule, antibody, which is produced by plasma cell, the terminal differentiated B cell. Immune response is orchestrated harmoniously by all these components mediated through antigen presenting cells such as dendritic cells. Immune responses can be divided into two ways: innate immune response and adaptive immune response depending on induction mechanism. Aging is a broad spectrum of physiological changes. Likewise other physiological changes, the immune components and responses are wane as aging is progressing. Immune responses become decline and dysregulating, which is called immunosenescense. Immune components of both innate and adaptive immune response are affected as aging progresses leading to increased vulnerability to infectious diseases. Numbers of immune cells and amounts of soluble immune factors were decreased in aged animal models and human and also functional and structural alterations in immune system were reduced and declined. Cellular intrinsic changes were discovered as well. Recent researches focusing on aging have been enormously growing. Many advanced tools were developed to bisect aging process in multi-directions including immune system area. This review will provide a broad overview of aging-associated changes of key components of immunity.

• Journal of Microbiology and Biotechnology
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• v.29 no.5
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• pp.813-819
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• 2019

Middle East respiratory syndrome coronavirus (MERS-CoV) induces severe respiratory impairment with a reported mortality rate of ~36% in humans. The absence of clinically available MERS-CoV vaccines and treatments to date has resulted in uncontrolled incidence and propagation of the virus. In vaccine design, fusion with the IgG Fc domain is reported to increase the immunogenicity of various vaccine antigens. However, limited reports have documented the potential negative effects of Fc fusion on vaccine antigens. To determine whether Fc fusion affects the immunogenicity of MERS-CoV antigen, we constructed a Fcassociated MERS-CoV spike protein (eS770-Fc, 110 kDa), whereby human IgG4 Fc domain was fused to MERS-CoV spike protein (eS770) via a Gly/Pro linker using baculovirus as the expression system. For comparative analyses, two eS770 proteins lacking the IgG4 Fc domain were generated using the IdeS protease ($eS770-{\Delta}Fc$) or His tag attachment (eS770-His) and the immunogenicity of the above constructs were examined following intramuscular immunization in mice. Contrary to expectations, non-Fc spike proteins ($eS770-{\Delta}Fc$, eS770-His; 90 kDa) showed higher immunogenicity than the Fc fusion protein (eS770-Fc). Moreover, unlike non-Fc spike proteins, eS770-Fc immunization did not elicit neutralizing antibodies against MERS-CoV. The lower immunogenicity of Fc-fused eS770 was related to alterations in the structural conformation of the spike protein. Taken together, our results indicate that IgG Fc fusion reduces the immunogenicity of eS770 by interfering with the proper folding structure.

• Genomics & Informatics
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• v.19 no.4
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• pp.44.1-44.9
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• 2021

Autism is a complex neurodevelopmental disorder, the prevalence of which has increased drastically in India in recent years. Neuroligin is a type I transmembrane protein that plays a crucial role in synaptogenesis. Alterations in synaptic genes are most commonly implicated in autism and other cognitive disorders. The present study investigated the neuroligin 3 gene in the Indian autistic population by sequencing and in silico pathogenicity prediction of molecular changes. In total, 108 clinically described individuals with autism were included from the North Karnataka region of India, along with 150 age-, sex-, and ethnicity-matched healthy controls. Genomic DNA was extracted from peripheral blood, and exonic regions were sequenced. The functional and structural effects of variants of the neuroligin 3 protein were predicted. One coding sequence variant (a missense variant) and four non-coding variants (two 5'-untranslated region [UTR] variants and two 3'-UTR variants) were recorded. The novel missense variant was found in 25% of the autistic population. The C/C genotype of c.551T>C was significantly more common in autistic children than in controls (p = 0.001), and a significantly increased risk of autism (24.7-fold) was associated with this genotype (p = 0.001). The missense variant showed pathogenic effects and high evolutionary conservation over the functions of the neuroligin 3 protein. In the present study, we reported a novel missense variant, V184A, which causes abnormal neuroligin 3 and was found with high frequency in the Indian autistic population. Therefore, neuroligin is a candidate gene for future molecular investigations and functional analysis in the Indian autistic population.

• BMB Reports
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• v.56 no.9
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• pp.520-525
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• 2023

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by cognitive decline. Several recent studies demonstrated that impaired adult neurogenesis could contribute to AD-related cognitive impairment. Adult subventricular zone (SVZ) neurogenesis, which occurs in the lateral ventricles, plays a crucial role in structural plasticity and neural circuit maintenance. Alterations in adult SVZ neurogenesis are early events in AD, and impaired adult neurogenesis is influenced by the accumulation of intracellular Aβ. Although Aβ-overexpressing transgenic 5XFAD mice are an AD animal model well representative of Aβ-related pathologies in the brain, the characterization of altered adult SVZ neurogenesis following AD progression in 5XFAD mice has not been thoroughly examined. Therefore, we validated the characterization of adult SVZ neurogenesis changes with AD progression in 2-, 4-, 8-, and 11-monthold male 5XFAD mice. We first investigated the Aβ accumulation in the SVZ using the 4G8 antibody. We observed intracellular Aβ accumulation in the SVZ of 2-month-old 5XFAD mice. In addition, 5XFAD mice exhibited significantly increased Aβ deposition in the SVZ with age. Next, we performed a histological analysis to investigate changes in various phases of adult neurogenesis, such as quiescence, proliferation, and differentiation, in SVZ. Compared to age-matched wild-type (WT) mice, quiescent neural stem cells were reduced in 5XFAD mice from 2-11 months of age. Moreover, proliferative neural stem cells were decreased in 5XFAD mice from 2 to 8 months of age. Furthermore, differentiations of neuroblasts were diminished in 5XFAD mice from 2-11 months of age. Intriguingly, we found that adult SVZ neurogenesis was reduced with aging in healthy mice. Taken together, our results revealed that impairment of adult SVZ neurogenesis appears with aging or AD progression.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.875-884
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• 2023

Hydrogen infiltration into metals has been reported to induce alterations in their mechanical properties under load. In this study, we conducted CTOD (Crack Tip Opening Displacement) tests on steel specimens designed for use in liquid hydrogen storage systems. Electrochemical hydrogen charging was performed using both FCC series austenitic stainless steel and BCC series structural steel specimens, while CTOD testing was carried out using a 500kN-class material testing machine. Results indicate a notable divergence in behavior: SS400 test samples exhibited a higher susceptibility to failure compared to austenitic stainless steel counterparts, whereas SUS 316L test samples displayed minimal changes in displacement and maximum load due to hydrogen charging. However, SEM (Scanning Electron Microscopy) analysis results presented challenges in clearly explaining the mechanical degradation phenomenon in the tested materials. This study's resultant database holds significant promise for enhancing the safety design of liquid hydrogen storage systems, providing invaluable insights into the performance of various steel alloys under the influence of hydrogen embrittlement.

• Molecules and Cells
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• v.46 no.11
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• pp.675-687
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• 2023

Accumulation of pathogenic amyloid-β disrupts the tight junction of retinal pigment epithelium (RPE), one of its senescence-like structural alterations. In the clearance of amyloid-β, the autophagy-lysosome pathway plays the crucial role. In this context, mammalian target of rapamycin (mTOR) inhibits the process of autophagy and lysosomal degradation, acting as a potential therapeutic target for age-associated disorders. However, efficacy of targeting mTOR to treat age-related macular degeneration remains largely elusive. Here, we validated the therapeutic efficacy of the mTOR inhibitors, Torin and PP242, in clearing amyloid-β by inducing the autophagy-lysosome pathway in a mouse model with pathogenic amyloid-β with tight junction disruption of RPE, which is evident in dry age-related macular degeneration. High concentration of amyloid-β oligomers induced autophagy-lysosome pathway impairment accompanied by the accumulation of p62 and decreased lysosomal activity in RPE cells. However, Torin and PP242 treatment restored the lysosomal activity via activation of LAMP2 and facilitated the clearance of amyloid-β in vitro and in vivo. Furthermore, clearance of amyloid-β by Torin and PP242 ameliorated the tight junction disruption of RPE in vivo. Overall, our findings suggest mTOR inhibition as a new therapeutic strategy for the restoration of tight junctions in age-related macular degeneration.

• Applied Microscopy
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• v.30 no.3
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• pp.285-293
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• 2000

The present study has been carried out to investigate the effect of fluoride toxicity on the morphology as well as inorganic chemical constituents of rat teeth. Rats were administered sodium fluoride at dose of 0 ppm, 100 ppm, 200 ppm and 300 ppm at the beginning of pregnancy. Animals were perfused intravascularly with glutaraldehyde and the incisors were removed. Changes in the protein composition of the secretory and maturation enamel were investigated using polyacrylamide gel electrophoresis (SDS PAGE). And the enamel surface of incisors was examined under scanning electron microscope (SEM). Changes of protein quantities were found significantly in high levels fluoride administration for experimental groups compared with control. The SDS PAGE analysis demonstrated as follows In control group, secretory phase enamel protein, amelogenins, was detected more quantities than experimental group. The enamelin, presence in maturation phase enamel , showed more quantifies than control enamel with an increasing fluoride concentration in the drinking water. Also, the scanning electron micrographic data showed hypoplastic, tough, uneven, pitted and cracked enamel surfaces covered with granular deposits as a result of excessive intake of fluoride. From these results we conclude that high dose of fluoride administration leads to severe structural alterations on the enamel surface and these structural changes could be through defective mineralization.

• Korean Journal of Biological Psychiatry
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• v.25 no.3
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• pp.60-71
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• 2018

Objectives A growing body of evidence has suggested that morphologic changes in cerebellum may be implicated with pathophysiology of major depressive disorder (MDD). The aim of this study is to investigate a difference in the volume and cortical thickness of the specific region of cerebellum between patients with MDD and healthy controls (HC). Methods A total of 127 patients with MDD and 105 HC participated in this study and underwent T1-weighted structural magnetic resonance imaging. We analyzed volume and cortical thickness of each twelve cerebellum regions divided by left and right and the volume and cortical thickness of the whole cerebellum from T1-weigted image of participants. One-way analysis of covariance was used to investigate the volume and cortical thickness difference of total and specific regions between two groups adjusting for age, gender, medication, and total intracranial cavity volume. Results We found that the patients with MDD had significantly greater volume in the left cerebellum lobule III region [false discovery rate (FDR)-corrected p = 0.034] compared to HC. Also, our findings indicate that cortical thickness of left lobule VIIB (FDR-corrected p = 0.032) and lobule VIIIB (FDR-corrected p = 0.032) are significantly thinner in the patients with MDD compared with the HC. No significant volume and cortical thickness differences were observed in other sub-regions of the cerebellum. The volumes and cortical thickness of whole cerebellum between patients with MDD and HC did not differ significantly. Conclusions We observed the region-specific volume and cortical thickness difference in cerebellum between the patients with MDD and HC. The results of our study implicate that the information about structural alterations in cerebellum with further replicative studies might provide a stepping stone toward a specific marker to diagnose MDD.

• Molecules and Cells
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• v.43 no.4
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• pp.408-418
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• 2020

The sinus node (SN) is located at the apex of the cardiac conduction system, and SN dysfunction (SND)-characterized by electrical remodeling-is generally attributed to idiopathic fibrosis or ischemic injuries in the SN. SND is associated with increased risk of cardiovascular disorders, including syncope, heart failure, and atrial arrhythmias, particularly atrial fibrillation. One of the histological SND hallmarks is degenerative atrial remodeling that is associated with conduction abnormalities and increased right atrial refractoriness. Although SND is frequently accompanied by increased fibrosis in the right atrium (RA), its molecular basis still remains elusive. Therefore, we investigated whether SND can induce significant molecular changes that account for the structural remodeling of RA. Towards this, we employed a rabbit model of experimental SND, and then compared the genome-wide RNA expression profiles in RA between SND-induced rabbits and sham-operated controls to identify the differentially expressed transcripts. The accompanying gene enrichment analysis revealed extensive pro-fibrotic changes within 7 days after the SN ablation, including activation of transforming growth factor-β (TGF-β) signaling and alterations in the levels of extracellular matrix components and their regulators. Importantly, our findings suggest that periostin, a matricellular factor that regulates the development of cardiac tissue, might play a key role in mediating TGF-β-signaling-induced aberrant atrial remodeling. In conclusion, the present study provides valuable information regarding the molecular signatures underlying SND-induced atrial remodeling, and indicates that periostin can be potentially used in the diagnosis of fibroproliferative cardiac dysfunctions.