Biology subjects

Kim, W.-Y.

Publications and source records attributed to Kim, W.-Y..

4 recordsLinked to original sources

bioRxiv2025

A nuclear pore complex component HOS1 mediates UV-B light-induced UVR8 nuclear localization for activating HY5 cascade in Arabidopsis

Upon ultraviolet-B (UV-B) exposure, the photoreceptor UVR8 translocates to the nucleus and interacts with COP1 to activate downstream transcription factors, notably including HY5. However, the mechanism of UVR8 nuclear import has remained unclear1,2. Here, we identified HOS1, a component of the nuclear pore complex (NPC), as a key mediator of UVR8 nuclear translocation under UV-B conditions. HOS1 directly interacts with UVR8 specifically in response to UV-B, facilitating its efficient import into the nucleus. Consistent with this role, HOS1-deficient mutants exhibit reduced HY5 protein accumulation, compromised UV-B tolerance, and impaired expression of HY5- regulated genes, including those involved in anthocyanin synthesis. These findings reveal a novel role of HOS1 in bridging UV-B perception in the cytoplasm and gene transcriptional activation in the nucleus by enabling UVR8 nuclear import. They highlight a distinct broader role of NPC components in coordinating plant transcriptional response to environmental stimuli.

plant biology↗

bioRxiv2025

N-Terminal Deleted Isoforms of E3 Ligase RNF220 (Isoform 4) Are Ubiquitously Expressed and Required for Mouse Muscle Differentiation.

Four isoform peptides of the novel E3 ligase RNF220 have been identified in humans. However, all of previous studies have predominantly focused on isoform 1, which consists of 566 amino acids (aa). Here, we show that a shorter isoform, isoform 4 (308 aa), lacking most of the N-terminus, is the predominant and ubiquitously expressed variant that warrants functional investigation. Both isoform 1 and isoform 4 are expressed in the brain; however, isoform 4 is the major isoform expressed in all other tissues in mice. Consistently, H3K4me3 ChIP-seq data from ENCODE reveal that the transcription start site for isoform 4 demonstrates broader and stronger activity across human tissues than that of isoform 1. Isoform 4 produces two peptides (4a and 4b) through alternative translation initiation, with isoform 4b displaying distinct subcellular localization and subnuclear structures. Notably, during embryonic stem cell differentiation into neural stem cells, isoform 1 expression increases, whereas isoform 4 expression decreases. In murine myoblasts, isoform 4 is the sole expressed isoform and is required for MyoD and myogenin expression, as well as for muscle differentiation. Our findings highlight isoform 4 as the ubiquitously and highly expressed variant, likely playing a fundamental role across tissues while exhibiting functional differences from isoform 1. These results emphasize the critical importance of isoform 4 in future studies investigating the biological functions of RNF220.

molecular biology↗

bioRxiv2021

A Calcium/Palmitoylation Switch Interfaces the Signaling Networks of Stress Response and Transition to Flowering

The precise timing of flowering in adverse environments is critical for plants to secure reproductive success. We report a novel mechanism controlling the time of flowering by which the palmitoylation-dependent nuclear import of protein SOS3/CBL4, a Ca2+-signaling intermediary in the plant response to salinity, results in the selective stabilization of the flowering time regulator GIGANTEA inside the nucleus under salt stress, while degradation of GIGANTEA in the cytosol releases the protein kinase SOS2 to achieve salt tolerance. S-acylation of SOS3 was critical for its nuclear localization and the promotion of flowering, but dispensable for salt tolerance. SOS3 interacted with the photoperiodic flowering components GIGANTEA and FKF1 on the CONSTANS gene promoter to sustain the transcription of CO and FT under salinity. Thus, SOS3 acts as a Ca2+- and palmitoylation-dependent molecular switch that fine-tunes flowering in a saline environment through the shared spatial separation and selective stabilization of GIGANTEA. The SOS3 protein connects two signaling networks to co-regulate stress adaptation and time of flowering. Short summaryS-acylation promoted the nuclear import of SOS3/CBL4 for the selective stabilization of the photoperiodic floral regulator GIGANTEA to fine-tune flowering time in a saline environment. Spatial separation of SOS3 acts as a molecular switch co-regulating stress adaptation and time of flowering.

plant biology↗

bioRxiv2018

Reversing Abnormal Neural Development by Inhibiting OLIG2 in Down Syndrome Human iPSC Brain Organoids and Neuronal Mouse Chimeras

Down syndrome (DS) is a common neurodevelopmental disorder, and cognitive defects in DS patients may arise form imbalances in excitatory and inhibitory neurotransmission. Understanding the mechanisms underlying such imbalances may provide opportunities for therapeutic intervention. Here, we show that human induced pluripotent stem cells (hiPSCs) derived from DS patients overproduce OLIG2+ ventral forebrain neural progenitors. As a result, DS hiPSC-derived cerebral organoids excessively produce specific subclasses of GABAergic interneurons and cause impaired recognition memory in neuronal chimeric mice. Increased OLIG2 expression in DS cells directly upregulates interneuron lineage-determining transcription factors. shRNA-mediated knockdown of OLIG2 largely reverses abnormal gene expression in early-stage DS neural progenitors, reduces interneuron production in DS organoids and chimeric mouse brains, and improves behavioral deficits in DS chimeric mice. Thus, altered OLIG2 expression may underlie neurodevelopmental abnormalities and cognitive defects in DS patients.

neuroscience↗