Biology subjects

Isotani, A.

Publications and source records attributed to Isotani, A..

8 recordsLinked to original sources

bioRxiv2025

Non-invasive estrous cycle classification in mice using convolutional neural networks

Accurately identifying the estrous cycle phases in laboratory mice is essential for neurological research, reproductive studies, and breeding programs. Here, we introduce a non-invasive approach using Convolutional Neural Networks (CNNs) to classify estrous stages from external genital images, with cytological smears serving as the reference standard for labeling. Images were curated, preprocessed, and augmented to ensure consistency and generalization. Seven pre-trained CNNs and a lightweight custom architecture, Repro Cycle Net (RCN), were evaluated. All models achieved accuracies above 75%, with RCN exceeding 83% and showing the lowest test loss, highlighting its efficiency despite a simple four-layer design. Saliency map analyses revealed that classification relied on perivaginal features, while irrelevant regions such as the fur area were largely ignored. Importantly, binary classification of estrus versus non-estrus directly informs mating feasibility, underscoring the immediate utility of this method for reproductive studies and colony management. This work demonstrates that combining deep learning with external genital observation enables efficient and reproducible estrous monitoring, supporting both experimental reliability and animal welfare.

bioinformatics↗

bioRxiv2023

Astrocyte-specific inhibition of primary cilium functions improves cognitive impairment during neuroinflammation by suppressing A1 astrocyte differentiation.

A1 astrocytes play a neurotoxic role in various neurodegenerative diseases. While inhibiting the differentiation of A1 astrocytes can slow disease progression, the mechanisms controlling A1 astrocyte differentiation are largely unknown. The primary cilium is a cellular organelle that receives extracellular signals and regulates cell proliferation, differentiation, and maturation. To elucidate the physiological function of the primary cilium in A1 astrocytes, we utilized primary astrocytes and an inflammation mouse model. We found that the length of the primary cilium was increased in astrocytes, and the inhibition of primary cilium formation inhibited their differentiation into A1 astrocytes. Since mice with systemic ciliogenesis defects exhibit embryonic lethality, the function of the primary cilium in adults has remained largely unclear. Therefore, we established conditional knockout (cKO) mice that specifically inhibit primary cilium function in astrocytes upon drug stimulation. In a neuroinflammation mouse model in which lipopolysaccharide (LPS) was intraperitoneally injected into wild-type mice, increases in A1 astrocyte number and primary cilium length were observed in the brain. In contrast, cKO mice exhibited a reduction in the proportions of A1 astrocytes and apoptotic cells in the brain. Additionally, the novel object recognition (NOR) score observed in the cKO mice was higher than that observed in the neuroinflammation model mice. These results suggest that the primary cilium in astrocytes is essential for A1 astrocyte differentiation, which leads to a decline brain function. We propose that regulating astrocyte-specific primary cilium signalling may be a novel strategy for the suppression of neuroinflammation.

neuroscience↗

bioRxiv2023

Generating an organ-deficient animal model using a multi-targeted CRISPR-Cas9 system

Gene-knockout animal models with organ-deficient phenotypes used for blastocyst complementation are generally not viable. Animals need to be maintained as heterozygous mutants, and homozygous mutant embryos yield only one-fourth of all embryos. In this study, we generated organ-deficient embryos using the CRISPR-Cas9-sgRNAms system that induces cell death with a single-guide RNA (sgRNAms) targeting multiple sites in the genome. The Cas9-sgRNAms system interrupted cell proliferation and induced cell ablation in vitro. The mouse model had Cas9 driven by the Foxn1 promoter with a ubiquitous expression cassette of sgRNAms at the Rosa26 locus (Foxn1Cas9; Rosa26_ms). It showed an athymic phenotype similar to that of nude mice but was not hairless. Eventually, a rat cell-derived thymus in an interspecific chimera was generated by blastocyst complementation of Foxn1Cas9; Rosa26_ms mouse embryos with rat embryonic stem cells. Theoretically, half of the total embryos have the Cas9-sgRNAms system because Rosa26_ms could be maintained as homozygous.

bioengineering↗

bioRxiv2022

Generation of rat lungs by blastocyst complementation in Fgfr2b-deficient mouse model

Regenerative medicine is a tool to compensate for the shortage of lungs for transplantation, but it remains difficult to construct a lung in vitro due to the complex three-dimensional structures and multiple cell types required. A blastocyst complementation method using interspecies chimeric animals has been attracting attention as a way to create complex organs in animals, but successful lung formation has not yet been achieved. Here, we applied a "reverse-blastocyst complementation method" to clarify the conditions required to form lungs in an Fgfr2b-deficient mouse model. We then successfully formed a rat-derived lung in the mouse model without generating a mouse line by applying a tetraploid-based organ-complementation method. Importantly, rat lung epithelial cells retained their developmental timing even in the mouse body. This result provides useful insights regarding the need to overcome the barrier of species-specific developmental timing in order to generate functional lungs in interspecies chimeras.

developmental biology↗

bioRxiv2021

T cell-intrinsic vitamin A metabolism and its signaling are targets for memory T cell-based cancer immunotherapy

Memory T cells play an essential role in infectious and tumor immunity. Vitamin A metabolites such as retinoic acid are immune modulators, but the role of vitamin A metabolism in memory T- cell differentiation is unclear. In this study, we identified retinol dehydrogenase 10 (Rdh10), which metabolizes vitamin A to retinal (RAL), as a key molecule for regulating T cell differentiation. T cell-specific Rdh10 deficiency enhanced memory T-cell formation through blocking RAL production in infection model. Epigenetic profiling revealed that retinoic acid receptor (RAR) signaling activated by vitamin A metabolites induced comprehensive epigenetic repression of memory T cell-associated genes, including TCF7, thereby promoting effector T-cell differentiation. Importantly, memory T cells generated by Rdh10 deficiency and blocking RAR signaling elicited potent anti-tumor responses in adoptive T-cell transfer setting. Thus, T cell differentiation is regulated by vitamin A metabolism and its signaling, which should be novel targets for memory T cell-based cancer immunotherapy.

immunology↗

bioRxiv2021

Trim41 is essential for preventing X chromosome chaotic synapsis in male mice

Meiosis is a hallmark event in germ cell development that accompanies sequential chromosome events executed by numerous molecules. Therefore, characterization of these factors is one of the best strategies to clarify the mechanism of meiosis. Here, we report tripartite motif-containing 41 (TRIM41), a ubiquitin ligase E3, as an essential factor for proper meiotic progression and fertility in male mice. Trim41 KO spermatocytes exhibited synaptonemal complex protein 3 (SYCP3) overloading, especially on the X chromosome, showing extensive self-synapsis of X chromosome and non-homologous synapsis between the X chromosome and autosomes. Furthermore, the mutant mice lacking the RING domain of TRIM41, required for the ubiquitin ligase E3 activity, phenocopied Trim41 KO mice. We then examined the behavior of mutant TRIM41 ({Delta}RING-TRIM41) and found that {Delta}RING-TRIM41 accumulated on the chromosome axes with overloaded SYCP3. This result showed that TRIM41 exerts the function on the chromosome axes. In summary, our study revealed that Trim41 is essential for preventing SYCP3 overloading and chaotic synapsis of the X chromosome, suggesting a TRIM41-mediated mechanism for regulating unsyapsed axes during male meiotic progression. Summary statementTrim41-disruption caused abnormal synapsis configuration of the X chromosome and complete infertility in male mice. Thus, TRIM41 prevents the sex chromosome from chaotic synapsis.

developmental biology↗

bioRxiv2021

Inhibition of N-myristoyltransferase Promotes Naive Pluripotency in Mouse and Human Pluripotent Stem Cells

Naive and primed states are distinct states of pluripotency during early embryonic development that can be captured and converted to each other in vitro. To elucidate the regulatory mechanism of pluripotency, we performed a recessive genetic screen of homozygous mutant mouse embryonic stem cells (mESCs) and found that suppression of N-myristoyltransferase (Nmt) promotes naive pluripotency. Disruption of Nmt1 in mESCs conferred resistance to differentiation. Suppression of Nmt in mouse epiblast stem cells (mEpiSCs) promoted the conversion from the primed to the naive state. This effect was independent of Src, which is a major substrate of Nmt and is known to promote differentiation of mESCs. Suppression of Nmt in naive-state human induced pluripotent stem cells (hiPSCs) increased the expression of the naive-state marker. These results indicate that Nmt is a novel target for the regulation of naive pluripotency conserved between mice and humans.

developmental biology↗

bioRxiv2020

Ets2 frame-shift mutant models express in-frame mRNA by exon skipping that complements Ets2 function in the skin

The Ets2 transcription factor has been implicated in various biological processes. An Ets2 mutant model, which lacks the DNA-binding domain (ETS domain), was previously reported to exhibit embryonic lethality caused by a trophoblast abnormality. This phenotype could be rescued by tetraploid complementation, resulting in pups with wavy hair. Here, we generated new Ets2 mutant models with deletions in exon 8 and with frame-shift mutations using the CRISPR/Cas9 method. Homozygous mutants could not be obtained by natural mating as previously reported. After rescuing with tetraploid complementation, homozygous mutant mice were generated, but these mice did not exhibit wavy hair phenotype. Our newly generated mice exhibited exon 8 skipping, which led to in-frame mutant mRNA expression in the skin and thymus but not in E7.5 embryos. As this in-frame mutation contained the ETS domain, the exon 8-skipped Ets2 mRNA was likely translated into protein in the skin that complemented the Ets2 function. Thus, these Ets2 mutant models, depending on the cell types, exhibited novel phenotypes due to exon skipping and are expected to be useful in several fields of research. Summary statementNew Ets2 mutant models showed embryonic lethal phenotype by a placental abnormality but did not exhibit a wavy hair phenotype as a previous model.

developmental biology↗