Biology subjects

Shigeoka, T.

Publications and source records attributed to Shigeoka, T..

5 recordsLinked to original sources

bioRxiv2026

Tissue-specific chromatin accessibility and co-factor availability together define ASCL1-dependent neural reprogrammability across germ layers during embryogenesis

The proneural transcription factor ASCL1 is well established as a pioneering neuronal reprogramming factor in several contexts. However, the extent to which distinct tissue types adopt a similar or divergent response to the same ASCL1 fate challenge is unclear. By expressing ASCL1 across germ layers and tissues of the developing Xenopus neurula embryo, we reveal widespread but largely distinct transcriptomic and chromatin responses to ASCL1. Ectopic ASCL1 can access partially open chromatin sites across all tissues, but it is able to further open those sites specifically in neuroectoderm. Using motif enrichment and accessibility analyses we identify Sox transcription factor motifs as enriched and preferentially accessible at ASCL1-bound regions in neuroectoderm. We show that co-expression of Sox3 and ASCL1 can enable the activation of otherwise refractory ASCL1 target genes in mesoderm and epidermal skin. Our findings reveal how the chromatin landscape and co-factor availability work together to modulate the response to transcription factor-driven fate challenge during development. Summary statementSingle-cell multi-omics reveals how chromatin accessibility and cofactor availability constrains ASCL1-driven neuronal reprogramming across tissues in the developing Xenopus embryo.

developmental biology↗

bioRxiv2024

Zbtb38 inhibits apoptosis by transcriptionally regulating XIAP expression

The X-linked inhibitor of apoptosis protein (XIAP) is a key suppressor of apoptosis, crucial for cellular differentiation, embryogenesis, and cancer progression. However, its upstream regulatory mechanisms remain poorly understood. Here, we demonstrate that the zinc finger transcription factor Zbtb38, a negative regulator of apoptosis, modulates XIAP expression in both loss- and gain-of-function experiments, irrespective of p53 expression. Notably, XIAP overexpression rescues the apoptosis induced by Zbtb38 knockdown, indicating that Zbtb38-associated apoptosis is at least partially XIAP-dependent. Mechanistically, Zbtb38 binds to E-box motifs within upstream regulatory regions of XIAP and activates its transcription. During embryonic stem (ES) cell differentiation and embryogenesis, Zbtb38 depletion increases apoptosis and reduces XIAP and Bcl-2 expression, underscoring their functional relevance in these processes. Analysis of human tumor datasets reveals a strong positive correlation between ZBTB38 and XIAP expression, with elevated ZBTB38 levels associated with high-grade malignancies. Furthermore, Zbtb38 knockdown induces apoptosis in cancer cells with reduced XIAP expression, regardless of p53 expression. Collectively, these findings uncover a novel Zbtb38-XIAP axis that regulates apoptosis during cellular differentiation, development, and oncogenesis, and highlight its therapeutic potential in XIAP-driven and p53-deficient tumors.

cell biology↗

bioRxiv2023

Granulomatous inflammatory responses are elicited in the liver of PD-1 knockout mice by de novo genome mutagenesis

Aimsprogrammed death-1 (PD-1) is a negative regulator of immune responses. Upon deletion of PD-1 in mice, symptoms of autoimmunity developed only after they got old. In a model experiment in cancer immunotherapy, PD-1 was shown to prevent cytotoxic T lymphocytes from attacking cancer cells that expressed neoantigens derived from genome mutations. Furthermore, the larger number of genome mutations in cancer cells led to the more robust anti-tumor immune responses after the PD-1 blockade. In order to understand the common molecular mechanisms underlying these findings, we hypothesize that we might have acquired PD-1 during evolution in order to avoid/suppress autoimmune reactions against neoantigens derived from mutations in the genome of aged individuals. Main methods: to test the hypothesis, we introduced random mutations into the genome of young PD-1-/- and PD-1+/+ mice. We employed two different procedures of random mutagenesis: administration of a potent chemical mutagen N-ethyl-N-nitrosourea (ENU) into the peritoneal cavity of mice and deletion of MSH2, which is essential for the mismatch-repair activity in the nucleus and, therefore, for the suppression of accumulation of random mutations in the genome. Key findingswe observed granulomatous inflammatory changes in the liver of the ENU-treated PD-1 knockout (KO) mice, but not in the wild-type (WT) counterparts. Such lesions also developed in the PD-1/MSH2 double KO mice, but not in the MSH2 single KO mice. Significance: the results we obtained support our hypothesis: PD-1 probably functions to avoid/suppress inflammatory responses against neoantigens derived from genome mutations in aged individuals.

immunology↗

bioRxiv2019

Receptor-specific interactome as a hub for rapid cue-induced selective translation in axons

During neuronal wiring, extrinsic cues trigger the local translation of specific mRNAs in axons via cell surface receptors. The coupling of ribosomes to receptors has been proposed as a mechanism linking signals to local translation but it is not known how broadly this mechanism operates, nor whether it can selectively regulate mRNA translation. We report that receptor-ribosome coupling is employed by multiple guidance cue receptors and this interaction is mRNA-dependent. We find that different receptors bind to distinct sets of mRNAs and RNA-binding proteins. Cue stimulation induces rapid dissociation of ribosomes from receptors and the selective translation of receptor-specific mRNAs in retinal axon growth cones. Further, we show that receptor-ribosome dissociation and cue-induced selective translation are inhibited by simultaneous exposure to translation-repressive cues, suggesting a novel mode of signal integration. Our findings reveal receptor-specific interactomes and provide a general model for the rapid, localized and selective control of cue-induced translation.

developmental biology↗

bioRxiv2018

On-site ribosome remodeling by locally synthesized ribosomal proteins in axons

Ribosomes are known to be assembled in the nucleolus, yet recent studies have revealed robust enrichment and translation of mRNAs encoding ribosomal proteins (RPs) in axons, far away from neuronal cell bodies. Using subcellular proteomics and live-imaging, we show that locally synthesized RPs incorporate into axonal ribosomes in a nucleolus-independent fashion. We revealed that axonal RP translation is regulated through a novel sequence motif, CUIC, that forms a RNA-loop structure in the region immediately upstream of the initiation codon. Inhibition of axonal CUIC-regulated RP translation leads to defects in local translation activity and axon branching, demonstrating the physiological relevance of the axonal ribosome remodeling. These results indicate that axonal translation supplies cytoplasmic RPs to maintain/modify local ribosomal function far from the nucleolus.

neuroscience↗