Biomedical subjects

Kenjiro Kosaki

Publications and source records attributed to Kenjiro Kosaki.

3 recordsLinked to original sources

PubMed2026

Characterization of stem cells from exfoliated deciduous teeth from a patient with Alagille syndrome carrying a JAG1 mutation.

PURPOSE: Alagille syndrome (ALGS) is an autosomal dominantly inherited disorder primarily caused by mutations in the Jagged Canonical Notch Ligand 1 (JAG1) gene. Although many pluripotent stem cells are well established, no patient-derived stem cells from exfoliated deciduous teeth (SHED) have been developed. In this study, we aimed to establish SHED from an ALGS patient carrying a heterozygous JAG1mut mutation. METHODS: We isolated SHED from a deciduous tooth of an ALGS patient with a heterozygous JAG1 mutation (ALGS-SHED) by the colony-forming unit-fibroblast (CFU-F) method. We then compared the characteristics of ALGS-SHED and healthy donor-derived control SHED (CONT-SHED). RESULTS: ALGS-SHED displayed mesenchymal stem cell features as indicated by CFU-F formation, immunophenotype, and mesenchymal multipotency into adipocytes, chondrocytes, and osteoblasts. ALGS-SHED showed reduced population doubling capacity and exhibited induced chondrogenic potency and diminished osteogenic potency, but similar hepatic potency. ALGS-SHED damaged in situ potency to form bile duct-like tubular structures in the livers of chronically CCl4-injured mice. CONCLUSIONS: We successfully established ALGS-SHED from an ALGS patient carrying a heterozygous JAG1 mutation. Our established ALGS-SHED may represent a potential model for studying ALGS involving a JAG1 mutation.

Alagille Syndrome↗

PubMed2026

Hearing loss associated with CDC42 in mice and humans (Takenouchi-Kosaki syndrome): CDC42 and RHOQ synergistically function in cochlear hair cells.

CDC42 is involved in multiple signaling pathways, including actin organization and polarity. We previously reported progressive sensorineural hearing loss (SNHL) in inner ear hair cell (HC)-specific Cdc42-knockout (Atoh1-Cre+/-;Cdc42flox/flox) mice. However, the phenotype was milder than expected, suggesting possible redundancy with other Rho-family GTPases. Thereafter, Takenouchi-Kosaki syndrome (TKS), caused by de novo CDC42 mutations and manifesting as SNHL, was reported, in which the p.Y64C mutation was speculated to be constitutively active. However, the relationship between CDC42 status and hearing phenotypes in TKS remains unclear. Using cell models, mouse models, and patient data, we propose that impaired and/or dysregulated cycling between GDP/inactive and GTP/active forms, through either loss-of-function or constitutive activation, can lead to SNHL. Furthermore, to test redundancy, we generated HC-specific Cdc42;RhoQ double-knockout (Atoh1-Cre+/-;Cdc42flox/flox;RhoQflox/flox) mice, which revealed synergistic roles of CDC42 and RHOQ in cochlear HCs. Supporting this synergy, MDCK cells with CDC42 and RHOQ double knockdown showed greater phospho-cofilin, a key regulator of actin turnover, elevation than single knockdowns.

CDC42↗

PubMed2025

Rescue of imprinted genes by epigenome editing in human cellular models of Prader-Willi syndrome.

Prader-Willi syndrome (PWS) is a genomic imprinting disorder caused by the loss of function of the paternal chromosome 15q11-13, resulting in a spectrum of symptoms associated with hypothalamic dysfunction. PWS patients lack the expression of paternally expressed genes (PEGs) in the 15q11-13 locus but possess an epigenetically silenced set of these genes in the maternal allele. Thus, activation of these silenced genes can serve as a therapeutic target for PWS. Here, we leverage CRISPR-based epigenome editing system to modulate the DNA methylation status of the PWS imprinting control region (PWS-ICR) in induced pluripotent stem cells (iPSCs) derived from PWS patients. Successful demethylation in the PWS-ICR restores the PEG expression from the maternal allele and reorganizes the methylation patterns in other PWS-associated imprinted regions beyond the PWS-ICR. Remarkably, these corrected epigenomic patterns and PEG expression are maintained following the differentiation of these cells into hypothalamic organoids. Finally, the single-cell transcriptomic analysis of epigenome-edited organoids demonstrates a partial restoration of the transcriptomic dysregulation observed in PWS. This study highlights the utility of epigenome editing technology as a therapeutic approach in addressing PWS and potentially other imprinting disorders.

Prader-Willi Syndrome↗