Biology subjects

Sawasaki, T.

Publications and source records attributed to Sawasaki, T..

7 recordsLinked to original sources

bioRxiv2026

Androgen receptor determines skeletal muscle sexual dimorphism

The molecular and functional bases of sexual dimorphism in skeletal muscle remain poorly understood. The androgen receptor (AR) is a major regulator of sex-biased gene expression in muscle, but its genomic targets and associated coregulators in vivo are incompletely defined. Using ChIL-seq and an AirID-AR knock-in mouse, we mapped AR-bound genes and AR-associated proteins in skeletal muscle and identified histone deacetylase-linked corepressors. We further identified myosin binding protein H (Mybph) as a female-biased AR-repressed gene conserved in mouse and human muscle. Mybph loss disrupted sarcomeric organization and selectively delayed postinjury force recovery in female mice. These findings define an in vivo AR regulatory network and identify AR-dependent Mybph repression as a potential mechanism contributing to skeletal muscle sexual dimorphism.

molecular biology↗

bioRxiv2025

LRBA promotes drug-induced liver injury and MASLD by scaffolding MAPK activation

LPS-responsive beige-like anchor protein (LRBA) regulates vesicular trafficking and receptor recycling, and its deficiency results in immunodeficiency characterized by hypogammaglobulinemia and autoimmune syndrome. However, its role in liver pathophysiology remains unclear. Here, we reveal a previously unrecognized function of LRBA as a critical intracellular scaffold for mitogen-activated protein kinase (MAPK) activation that promotes liver injury. Lrba-/-mice exhibit reduced acetaminophen (APAP)-induced hepatic necrosis through the suppression of JNK activation. In a model of metabolic dysfunction-associated steatotic liver disease (MASLD) induced by a high-fat, high-cholesterol (HFHC) diet, Lrba deficiency reduces hepatic inflammation, fibrosis, and Kupffer cell activation. Mechanistically, LRBA homodimers directly interact with specific mitogen-activated protein kinase kinase kinases (MAP3Ks), including transforming growth factor-{beta}-activated kinase 1 (TAK1) and mixed-lineage kinase 3 (MLK3), to facilitate their activation. LRBA, which is primarily expressed in hepatocytes under physiological conditions, is upregulated in non-parenchymal cells such as Kupffer cells and cholangiocytes in both HFHC diet-fed mice and patients with MASLD and cirrhosis, linking its scaffolding function to pathological inflammation. Thus, LRBA promotes liver disease progression by amplifying inflammatory signaling.

cell biology↗

bioRxiv2025

Sex-biased transcriptome in embryonic mouse cortices under Pax6 haploinsufficiency highlights Pbdc1 as a candidate regulator

Mutations in Pax6, encoding a transcription factor essential for brain patterning and neurogenesis, have been linked to female-biased cortical malformations and behavioral abnormalities, yet the molecular basis remains unclear. Here we show that Pax6 haploinsufficiency (Sey/+) produces more pronounced sex-biased alterations in the transcriptomes and cytoarchitecture of embryonic mouse cortices than those in wild-type and homozygous mutants (Sey/Sey). Pbdc1, a previously uncharacterized X-linked gene implicated in autism, is selectively upregulated in Sey/+ females and proximity-dependent protein-protein interaction analysis reveals Pbdc1 interacts with RNA-splicing factors. Moreover, Pbdc1 overexpression reduces intermediate progenitor cells in the developing cortex. ChIP-qPCR further demonstrates Pax6 and BAF occupancy at the Pbdc1 promoter in WT embryos of both sexes and CUT&Tag shows H3K4me3 elevation selectively in Sey/+ females. Our findings indicate that partial loss of Pax6 shapes the embryonic cortical transcriptomes and cytoarchitecture in a sex-dependent manner and highlight Pbdc1 as a candidate regulator of sex-biased corticogenesis.

developmental biology↗

bioRxiv2025

Comparative Proteomic Profiling of Receptor Kinase Signaling Reveals Key Trafficking Components Enforcing Plant Stomatal Development

Receptor kinases are pivotal for growth, development, and environmental response of plants. Yet, their regulatory mechanisms and spatial dynamics are still underexplored. The ERECTA-family receptor kinases coordinate diverse developmental processes, including stomatal development. To understand the proteomic landscape of the ERECTA-mediated signaling pathways, we here report comparative analyses of the ERECTA interactome and proximitome by epitope-tagged affinity-purification (ET-AP) and TurboID-based proximity labeling (TbID-PL) mass-spectrometry, respectively. While ET-AP successfully recovered receptor complex components (e.g., TOO MANY MOUTHS), TbID-PL effectively captured transient associations with the components of endosomal trafficking, i.e., clathrin-mediated endocytosis (CME) machinery. We further identify that specific subfamily members of phosphatidylinositol-binding clathrin assembly proteins (PICALMs) interact with and synergistically regulate ERECTA internalization. Mutations of these PICALMs impair ERECTA endocytosis and lead to excessive stomatal clustering by dampening the downstream signaling output. Taken together, our work provides a proteomic atlas of the ERECTA signaling network and suggests that timely removal of receptor kinase by the endocytosis machinery is essential for active signal transduction enforcing stomatal patterning.

plant biology↗

bioRxiv2025

In-cell proximity target validation methods for heterobifunctional molecules with CRBN- or VHL-binder using AirID

Heterobifunctional molecules, such as proteolysis-targeting and autophagy-targeting chimera, represent new drug concepts. They are composed of two protein binders that can induce proximity interactions between two proteins and protein catalysis. Currently, cereblon (CRBN)- and von Hippel-Lindau (VHL)-binders with thalidomide- and VH032-backbones are widely used as E3 ligase binders. Here we developed a method to validate proteins that interact with heterobifunctional molecules in cells using AirID, a proximity biotinylation enzyme. Interactome of target proteins was validated for six heterobifunctional molecules. ThBD-AirID, a fusion of the thalidomide-binding domain (ThBD) of CRBN and AirID, effectively biotinylated the target proteins. AirID fused to full-length VHL also exhibited highly effective biotinylation. Heterobifunctional molecules with the same target binder but different E3 binders showed different proximity interactome profiles in cells. Analysis using ThBD-AirID revealed a nuclear interaction between androgen receptor and ARV-110. AirID-fused ThBD and VHL could be useful for validating the heterobifunctional molecular interactome in cells.

molecular biology↗

bioRxiv2021

OTUD1 deubiquitylase regulates NF-κB- and KEAP1-mediated inflammatory responses and reactive oxygen species-associated cell death pathways

Deubiquitylating enzymes (DUBs) regulate numerous cellular functions by removing ubiquitin modifications. We examined the effects of 88 human DUBs on linear ubiquitin chain assembly complex (LUBAC)-induced NF-{kappa}B activation, and identified OTUD1 as a potent suppressor. OTUD1 regulates the canonical NF-{kappa}B pathway by hydrolysing K63-linked ubiquitin chains from NF-{kappa}B signalling factors, including LUBAC. OTUD1 negatively regulates the canonical NF-{kappa}B activation, apoptosis, and necroptosis, whereas OTUD1 upregulates the interferon (IFN) antiviral pathway. The N-terminal intrinsically disordered region of OTUD1, which contains an EGTE motif, is indispensable for KEAP1-binding and NF-{kappa}B suppression. OTUD1 is involved in the KEAP1-mediated antioxidant response and reactive oxygen species (ROS)-induced cell death, oxeiptosis. In Otud1-/--mice, inflammation, oxidative damage, and cell death were enhanced in inflammatory bowel disease, acute hepatitis, and sepsis models. Thus, OTUD1 is a crucial regulator for the inflammatory, innate immune, and oxidative stress responses and ROS-associated cell death pathways.

cell biology↗

bioRxiv2020

PLZF is a new substrate of CRBN with thalidomide and 5-hydroxythalidomide

Thalidomide induces cereblon (CRBN)-dependent degradation of proteins. Human cytochrome P450s are thought to provide two monohydroxylated metabolites from thalidomide, and the metabolites are also considered to be involved in thalidomide effects. However, it remains unclear. We report that human PLZF/ZBTB16 is a target protein of CRBN with thalidomide and its derivatives, and that 5-hydroxythalidomide has high potential for degrading PLZF. Using a human transcription factor protein array produced by a wheat cell-free protein synthesis system, PLZF was found to bind to CRBN with thalidomide. PLZF is degraded by the CRL4CRBN complex with thalidomide and its derivatives. Mutagenesis analysis revealed that both 1st and 3rd zinc finger domains conserved in vertebrates are recognized for thalidomide-dependent binding and degradation by CRBN. In chicken limbs, knockdown of Plzf induced skeletal abnormalities, and Plzf was degraded after thalidomide or 5-hydroxythalidomide treatment. Our findings suggest that PLZF is a pivotal substrate involving thalidomide-induced teratogenesis.

pharmacology and toxicology↗