Biology subjects

Cho, S. K.

Publications and source records attributed to Cho, S. K..

4 recordsLinked to original sources

bioRxiv2025

Novel mouse model of cerebral microbleeds created by Crispr/Cas9-mediated Col4a1 deletion in adult brain microvessels

Cerebral small vessel disease is a leading cause of cognitive decline and stroke in the elderly, with cerebral microbleeds (CMBs) as one of the key imaging biomarkers. Our understanding of its pathophysiology remains limited due to the lack of appropriate animal models. We report a novel mouse CMB model created by disrupting collagen IV, a core component of the vascular basement membrane (BM), specifically within brain microvessels. Targeted deletion of Col4a1 was achieved in adult mice using brain endothelial-specific AAV vectors with CRISPR/Cas9. MRI revealed numerous CMBs with distributions similar to those of human CMBs. CMB burden increased progressively over six months following Col4a1 deletion in a dose-dependent manner, accompanied by cognitive decline and motor incoordination. Histological examination revealed hemosiderin deposits corresponding to MRI-detected CMBs without evidence of macroscopic hemorrhage or white matter lesions, while ultrastructural analysis demonstrated significant BM thinning in Col4a1-depleted microvessels. Analysis of human MRI and genomic data identified significant associations between CMB susceptibility and genetic variants in TIMP2, an endogenous inhibitor of the matrix-degrading enzyme MMP2, underscoring the clinical relevance of our model. These findings establish a direct causal relationship between microvessel COL4A1 and CMB, suggesting that dysregulated collagen IV homeostasis in BM underlies CMB development.

neuroscience↗

bioRxiv2023

A phosphorylation-deficient ribosomal protein eS6 is largely functional in Arabidopsis thaliana, rescuing mutant defects from global translation and gene expression to photosynthesis and growth

The eukaryote-specific ribosomal protein of the small subunit eS6 is phosphorylated through the Target of rapamycin (TOR) kinase pathway. Although this phosphorylation event responds dynamically to environmental conditions and has been studied for over 50 years, its biochemical and physiological significance remains controversial and poorly understood. Here we report data from Arabidopsis thaliana, which indicate that plants expressing only a largely phospho-deficient isoform of eS6 grow essentially normally under laboratory conditions. The eS6A (RPS6A) paralog of eS6 functionally rescued double mutations in both rps6a and rps6b genes when expressed at approximately twice the wild-type dosage. A mutant isoform of eS6A lacking the major six phosphorylatable serine and threonine residues in its carboxyl-terminal tail also rescued the lethality, rosette growth, and polyribosome loading of the double mutant. It also complemented many mutant phenotypes of rps6 that were newly characterized here, including photosynthetic efficiency, and the vast majority of gene expression defects that were measured by transcriptomics and proteomics. However, compared to plants rescued with a phospho-enabled version of eS6A, the phospho-deficient seedlings retained a mild pointed-leaf phenotype, root growth was reduced, and certain cell cycle related mRNAs and ribosome biogenesis proteins were misexpressed. The residual defects of the phospho-deficient seedlings could be understood as an incomplete rescue of the rps6 mutant defects, with little or no evidence for gain-of-function defects. As expected, the phospho-deficient eS6A also rescued the rps6a and rps6b single mutants; however, phosphorylation of the eS6B paralog remained lower than predicted, further underscoring that plants can tolerate phospho-deficiency of eS6 well. Our data also yield new insights into how plants cope with mutations in essential, duplicated ribosomal protein isoforms.

plant biology↗

bioRxiv2019

Light activates the translational regulatory GCN2 kinase via reactive oxygen species emanating from the chloroplast

Cytosolic mRNA translation is subject to global and mRNA-specific controls. Phosphorylation of translation initiation factor eIF2 anchors a reversible switch that represses translation globally. The stress-responsive GCN2 kinase is the only known kinase for eIF2 in Arabidopsis. Here we show that conditions that generate reactive oxygen species (ROS) in the chloroplast, such as dark-light transitions, high light, and the herbicide methyl viologen all rapidly activated the GCN2 kinase, whereas mitochondrial and ER stress did not. In addition, GCN2 activation was light dependent and mitigated by photosynthesis inhibitors and ROS quenchers. Accordingly, seedling growth of multiple gcn2 mutant alleles was retarded under conditions of excess light, implicating the GCN2-eIF2 pathway in responses to light and associated ROS. Once activated, the GCN2 kinase preferentially suppressed the ribosome loading of mRNAs for functions such as mitochondrial ATP synthesis, the chloroplast thylakoids, vesicle trafficking, and translation. The transcriptome of gcn2 mutants was sensitized to abiotic stress, including oxidative stress, as well as innate immune responses. Accordingly, gcn2 displayed defects in immune priming by the fungal elicitor, chitin. In conclusion, we provide evidence that reactive oxygen species produced by the photosynthetic apparatus help to activate the highly conserved GCN2 kinase, leading to eIF2 phosphorylation and thus affecting the status of the cytosolic protein synthesis apparatus.

plant biology↗

bioRxiv2018

Genetic predisposition to hypouricemia on whole-exome sequencing analysis and its utilities in primary screening purposes

Differentiating between inherited renal hypouricemia and transient hypouricemia is challenging. Here, we aimed to describe the genetic predisposition of hypouricemia patients using whole-exome sequencing (WES) and assess the feasibility for genetic diagnosis in primary screening. WES was performed for the discovery of diagnostic markers in discovery cohorts (N=31). Two known genetic markers SLC22A12 c.774G>A (p.Trp258*) and SLC22A12 c.269G>A (p.Arg90His) were identified, We genotyped for the 2 SLC22A12 SNPs among screened 50 hypouricemia subjects for the replication cohorts; 47 carried known SLC22A12 markers; three unexplained hypouricemic cases were analyzed by using WES. We used 46 healthy internal controls for the variant discovery. Four novel variants of SLC22A12, c.408C>A (p.Asn136Lys), c.674C>A (p.Thr225Lys), c.851G>A (p.Arg284Gln), and c.1285G>A (p.Glu429Lys), and one novel variant of SLC2A9, c. 376A>G (p.Met155Val), were identified. After filtering out known genes (SLC22A12 and SLC2A9), the p.Arg78His variant in ASB12 was overlapped in two unexplained conditions. This is the first attempt to investigate the effectiveness of integrating exome sequencing and genotype into the clinical care for hypouricemia and determine the value of genetic diagnostic screening for hypouricemia in the clinical setting. Screening of just two SNPs (p.Trp258* and p.Arg90His) identified 87.7% (71/81) of patients with hypouricemia. Early identification and intervention of hypouricemia is feasible using genetic screening to prevent acute kidney injury, especially for soldiers and athletics.

genetics↗