https://scholar.gist.ac.kr/handle/local/7974 Wed, 04 Feb 2026 10:07:55 GMT 2026-02-04T10:07:55Z https://scholar.gist.ac.kr/handle/local/19877 Title: Unwinding Mechanism of SARS-CoV Helicase (nsp13) by Biochemical and Single-molecular Studies Author(s): Jeongmin Yu Abstract: The recent outbreak of coronavirus diseases has highlighted the urgent need for effective therapeutic agents and vaccines. One potential therapeutic target is the non-structural protein 13 (nsp13) helicase of Severe Acute Respiratory Syndrome (SARS) CoV, which plays an essential role in the viral replication process and has a conserved amino acid sequence between species. Although the replication of coronaviruses and other retroviruses occurs in the cytoplasm of infected cells, little is known about the detailed mechanism of nsp13 unwinding activity. To address this, I utilized biochemical approaches and biophysical single-molecule assays to investigate the molecular unwinding mechanism of nsp13. In the first part of the study, I demonstrated that nsp13 exhibits cooperative unwinding activity on single-stranded regions of DNA, with inhibition by re-zipping. Additionally, I found that nsp13 interacts with double-stranded regions under the influence of ADP, leading to transient destabilization of the double strands, which enhances cooperative unwinding activity. These findings suggest a unique model that nsp13 exhibits unwinding activity through different cooperative actions. In second part of study, I further demonstrated that nsp13 can efficiently unwind double-stranded DNA under physiological concentrations of Ca2+ found in the cytosolic DMVs. Importantly, nsp13 achieves this unwinding activity while performing ATP hydrolysis in the presence of Ca2+. These novel findings provide new insights into the properties of nsp13 in the range of calcium in cytosolic DMVs. Taken together, understanding the molecular mechanism of nsp13 unwinding activity may provide important approaches into the development of effective therapeutic strategies against the coronavirus diseases that continue to affect humanity. Sun, 31 Dec 2023 15:00:00 GMT https://scholar.gist.ac.kr/handle/local/19877 2023-12-31T15:00:00Z https://scholar.gist.ac.kr/handle/local/19858 Title: Translational Research on Novel Therapeutic approaches for Treating Skeletal muscle atrophy Kim Hyun-Jun School of Life Sciences Gwangju Institute of Science and Technology Author(s): Hyun-Jun Kim Abstract: Skeletal muscle atrophy arises from numerous factors, including aging, hormonal imbalances, and inflammation, and contributes significantly to socioeconomic burdens. Advanced metastasis often leads to cachexia, a complex syndrome characterized by muscle wasting and responsible for approximately one-third of cancer-related deaths. Despite the severe impact of both sarcopenia and cancer cachexia, no approved drug therapies currently exist for either condition. Among potential therapeutic targets, Arachidonate 5-lipoxygenase (Alox5) has gained attention for its role in various diseases, while C-X-C motif chemokine ligand 5 (CXCL5), a pro-inflammatory cytokine secreted by cancer-associated fibroblasts (CAFs), has been implicated in cancer progression and immune cell recruitment. However, the roles of Alox5 inhibition in sarcopenia and CXCL5 neutralization in cancer cachexia have not been fully explored. This study focused on investigating the potential of Alox5 inhibition and CXCL5 neutralization as therapeutic strategies for muscle atrophy. Using cell-based models, animal studies, and human skeletal muscle primary cells, we evaluated the effects of Alox5 inhibition in sarcopenia and CXCL5 neutralization in cancer cachexia. Malotilate, a clinically approved drug with Alox5-inhibitory properties, was identified as a candidate for repurposing. The mechanisms of action were assessed by evaluating the expression of key regulatory pathways involved in muscle atrophy, with gene knockdown and RNA sequencing confirming the effects. In sarcopenia models, Alox5 inhibition via malotilate treatment showed significant protective effects against muscle wasting. Myotubes treated with dexamethasone or conditioned media (CM) exhibited a marked reduction in catabolic responses when treated with malotilate. Similarly, Alox5 gene knockdown in these models provided anti-atrophy benefits without affecting the myogenic differentiation process. In vivo 김현준Hyun-Jun Kim ( ), Translational Research on Novel Therapeutic approaches for Treating Skeletal muscle atrophy 근감소증 치료를 위한 신규 치료제에 대한 중개연구( ), School of Life Sciences, 130p, Prof. Darren Williams PhD/LS 20184016 studies demonstrated that Alox5 inhibition preserved muscle mass, increased muscle fiber cross-sectional area, and improved muscle force/strength, while downregulating atrogene expression. In aging models of sarcopenia, malotilate preserved fast-twitch muscle fibers, further emphasizing the potential of Alox5 inhibition as a treatment for sarcopenia. In contrast, for cancer cachexia, CXCL5 neutralization emerged as a promising strategy. Neutralizing CXCL5 effectively inhibited cachexia in mice co-injected with HCT 116 colon cancer cells and CAFs. The suppression of CXCL5 triggered hypertrophy-related PI3K-AKT-MyoG signaling pathways and facilitated the remodeling of the muscle extracellular matrix. CAFs were identified as the primary source of CXCL5 in patient-derived tumor samples strongly associated with cachexia. Importantly, these effects were specific to the atrophy condition induced by cancer and were not observed in normal skeletal muscle. Furthermore, pharmacological targeting of Alox5 provided protection against muscle atrophy in human myotubes, reinforcing its potential application beyond cancer cachexia. These findings highlight distinct yet complementary therapeutic avenues: Alox5 inhibition shows promise for treating sarcopenia by protecting against muscle wasting and preserving muscle function, while CXCL5 neutralization offers a novel strategy for combating cancer cachexia by targeting pro-inflammatory cytokines within the tumor microenvironment. Together, these approaches provide a foundation for developing effective treatments for muscle atrophy across different pathological conditions. Tue, 31 Dec 2024 15:00:00 GMT https://scholar.gist.ac.kr/handle/local/19858 2024-12-31T15:00:00Z https://scholar.gist.ac.kr/handle/local/31974 Title: Transcriptomic Responses of Testis to Aging and Ethanol in Mice Author(s): Gwidong Han Abstract: PART I: Transcriptomic Responses of Testis to Aging in Mice Male reproductive aging, or andropause, is associated with gradual age-related changes in testicular properties, sperm production, and erectile function. The testis, which is the primary male reproductive organ, produces sperm and androgens. To understand the transcriptional changes underlying male reproductive aging, I performed transcriptome analysis of aging testes in mice. A total of 31,386 mRNAs and 9387 long non-coding RNAs (lncRNAs) were identified in the mouse testes of diverse age groups (3, 6, 12, and 18 months old) by total RNA sequencing. Of them, 1571 mRNAs and 715 lncRNAs exhibited changes in their levels during testicular aging. Most of these aging-related transcripts exhibited slight and continuous expression changes during aging, whereas some (9.6%) showed larger expression changes. The aging-related transcripts could be classified into diverse expression patterns, in which the transcripts changed mainly at 3-6 months or at 12-18 months. My subsequent in silico analysis provided insight into the potential features of testicular aging-related mRNAs and lncRNAs. I identified testis-specific aging-related transcripts (121 mRNAs and 25 lncRNAs) by comparison with a known testis-specific transcript profile, and then predicted the potential reproduction-related functions of the mRNAs. By selecting transcripts that are altered only between 3 and 18 months, I identified 46 mRNAs and 34 lncRNAs that are stringently related to the terminal stage of male reproductive aging. Some of these mRNAs were related to hormonal regulation. Finally, my in silico analysis of the 34 aging-related lncRNAs revealed that they co-localized with 19 testis-expressed protein-coding genes, 13 of which are considered to show testis-specific or -predominant expression. These nearby genes could be potential targets of cis-regulation by the aging-related lncRNAs. Collectively, my results identify a number of testicular aging-related mRNAs and lncRNAs in mice and provide a basis for the future investigation of these transcripts in the context of aging-associated testicular dysfunction. PART II: Transcriptomic Responses of Testis to Ethanol in Mice Alcohol consumption is widely known to have detrimental effects on various organs and tissues. The effects of ethanol on male reproduction have been studied at the physiological and cellular levels, but no systematic study has examined the effects of ethanol on male reproduction-related gene expression. I employed a model of chronic ethanol administration using the Lieber-DeCarli diet. Ethanol-fed mice showed normal testicular and epididymal integrity, and sperm morphology, but decreased sperm count. Total RNA sequencing analysis of testes from ethanol-fed mice showed that a small fraction (∼ 2%) of testicular genes were differentially expressed in ethanol-fed mice and that, of these genes, 28% were cell-type specific in the testis. Various in silico analyses were performed, and gene set enrichment analysis revealed that sperm tail structure-related genes, including forkhead box J1 (Foxj1), were down-regulated in testes of ethanol-fed mice. Consistent with this result, ethanol- fed mice exhibited decreased sperm motility. This study provides the first comprehensive transcriptomic profiling of ethanol-induced changes in the mouse testis, and suggests gene expression profile changes as a potential mechanism underlying ethanol-mediated reproductive dysfunction, such as impaired sperm motility.|Part I. 생쥐에서의 노화에 따른 정소 전사체 반응 남성 생식 노화 (Andropause)는 정소의 구조 및 기능 변화, 정자 생성 감소, 발기 기능 저하 등과 관련된 점진적인 생리적 변화로 정의된다. 본 연구에서는 생쥐 고환의 연령별 전사체 분석을 통해 생식 노화에 수반되는 전사적 변화를 규명하고자 하였다. RNA 시퀀싱을 통해 3, 6, 12, 18 개월령 생쥐 정소에서 31,386 개의 mRNA 와 9387 개의 긴 비암호화 RNA (lncRNA)를 동정하였으며, 이 중 1571 개의 mRNA 와 715 개의 lncRNA 가 연령에 따라 유의한 발현 변화를 보였다. 대부분의 노화 관련 전사체는 작고 점진적인 발현 변화 양상을 보였으나, 약 9.6%는 뚜렷한 변화 폭을 나타냈다. 발현 패턴 분석을 통해 이들 전사체는 3–6 개월 또는 12–18 개월 구간에서 주요한 변화를 보이는 군으로 분류되었다. 이어진 in silico 분석을 통해 정소 특이적 전사체와의 비교를 통해 노화 관련 정소 특이 전사체(121 개 mRNA, 25 개 lncRNA)를 규명하였고, 일부는 생식 기능 조절과 관련된 기능을 가질 것으로 예측되었다. 특히, 3 개월과 18 개월 사이에서만 변화하는 전사체를 기준으로 노화와 연관된 mRNA(46 개)와 lncRNA(34 개)를 선별하였으며, 일부는 호르몬 조절에 관여하는 것으로 나타났다. 또한, 노화 관련 lncRNA 중 34 개는 정소 특이적으로 발현되는 단백질 코딩 유전자(19 개)에 가까이 위치 (co-localize)하며, 이들 중 13 개는 cis-조절의 잠재적 표적일 수 있음을 제시하였다. 본 연구는 정소 노화와 관련된 전사체 네트워크를 포괄적으로 제시하며, 남성 생식 기능 저하의 분자적 기전을 이해하는 데 기초 자료를 제공한다. Part II. 생쥐에서의 에탄올 급여에 따른 정소 전사체 반응 알코올 섭취는 다양한 장기와 조직에 해로운 영향을 미치는 것으로 널리 알려져 있다. 에탄올이 남성 생식에 미치는 영향은 생리학적 및 세포 수준에서 여러 차례 연구되었지만, 생식 관련 유전자 발현에 미치는 영향을 체계적으로 분석한 연구는 없었다. 본 연구에서는 Lieber-DeCarli 식이법을 이용한 만성 에탄올 급여 모델을 사용하였다. 에탄올을 투여받은 마우스는 정소과 부정소의 구조적 이상은 없었으며, 정자 형태 역시 정상이었으나 정자 수는 감소하였다. 에탄올 급여 마우스의 정소에 대해 수행한 RNA 시퀀싱 분석 결과, 정소 유전자 중 약 2% 정도만이 차등 발현되었으며, 이 중 28%는 정소 내의 세포 특이 발현 유전자였다. 다양한 in silico 분석을 수행한 결과, 유전자 집합 풍부도 분석 (GSEA)에서 Foxj1 을 포함한 일부 정자 꼬리 구조 관련 유전자의 발현이 감소됨이 확인되었다. 이러한 결과에 부합하게, 에탄올 급여 마우스는 정자 운동성 감소를 보였다. 본 연구는 에탄올 급여에 따른 정소 전사체 변화를 포괄적으로 규명한 최초의 연구로서, 에탄올로 인한 생식 장애, 특히 정자 운동성 저하의 잠재적 기전으로서 유전자 발현 변화의 가능성을 제시한다. Tue, 31 Dec 2024 15:00:00 GMT https://scholar.gist.ac.kr/handle/local/31974 2024-12-31T15:00:00Z https://scholar.gist.ac.kr/handle/local/19830 Title: The Role of Posttranslational Modifications in Endothelial BMP Signaling Author(s): Han, Orjin Abstract: Bone Morphogenetic Protein (BMP) signaling plays a crucial role in endothelial cell (EC) biology, particularly in regulating vascular development and angiogenesis. Posttranslational modifications, such as ubiquitination and palmitoylation, have emerged as essential mechanisms for fine-tuning the activity of BMP receptors and downstream SMAD proteins. Despite their significance, the specific roles of these modifications in endothelial BMP signaling remain poorly understood, particularly in ECs. This study aimed to investigate how Posttranslational modifications, specifically ubiquitination and palmitoylation, regulate BMP signaling in ECs, focusing on the differential regulation of BMP receptors and SMAD proteins. Our findings reveal that ALK2 protein levels, despite being expressed at transcript levels in both arterial and venous ECs, are specifically downregulated in arterial ECs through Notch signaling-induced ubiquitination and subsequent lysosomal degradation. This regulation is mediated by the Notch-SPSB1 axis, which selectively targets ALK2 for degradation, ensuring a BMP signaling bias in venous ECs. Furthermore, SMAD1, rather than SMAD5, was found to be the primary transducer of BMP signals in ECs. Notably, palmitoylation of SMAD1 is critical for its nuclear localization and activation in response to BMP ligands, whereas SMAD5 is minimally affected by this modification in ECs. Chemical inhibition or mutation-based disruption of palmitoylation significantly impaired SMAD1 signaling, demonstrating the importance of lipid-based modifications in BMP signal transduction. This study provides novel insights into the Posttranslational regulation of BMP signaling in ECs, highlighting the roles of ubiquitination and palmitoylation in modulating the activity of BMP receptors and SMAD proteins. The differential regulation of BMP signaling in arterial and venous ECs through these modifications underscores the complexity of endothelial heterogeneity and its significance in vascular development. Tue, 31 Dec 2024 15:00:00 GMT https://scholar.gist.ac.kr/handle/local/19830 2024-12-31T15:00:00Z