Biology subjects

Watabe, T.

Publications and source records attributed to Watabe, T..

7 recordsLinked to original sources

bioRxiv2026

Three-dimensional vascular microenvironments uncover endothelial plasticity during TGF-β2-driven vascular remodeling

The tumor microenvironment plays a pivotal role in tumor development, harboring elements such as endothelial cells, immune cells, fibroblasts, and soluble factors such as transforming growth factor-{beta} (TGF-{beta}) family. TGF-{beta} family regulates cell development and promotes tumor invasion, metastasis, angiogenesis, and endothelial-to-mesenchymal transition (EndoMT). Here, we investigate the effects of TGF-{beta} signaling on vascular remodeling using a three-dimensional (3D) vascular network in a microfluidic device. Using both a co-culture (3D-Co) and simplified endothelial monoculture (3D-CM), we demonstrate that TGF-{beta} signaling reduces the quality and functionality of the vasculature by regressing them. In addition, we observed the upregulation of EndoMT-related markers in mRNA and protein expressions, suggesting the induction of EndoMT in 3D vascular networks. The increased vascular permeability stimulated by TGF-{beta}2 also supports the loss of endothelial identity in the 3D-Co. Transcriptomic analysis revealed the coordinated activation of pathways associated with cell migration and EndoMT, along with the suppression of cell cycle progression. A comparative analysis of two-dimensional (2D) and 3D cultures revealed a fundamentally distinct endothelial response to TGF-{beta}2 in the 3D context, including metabolic reprogramming. These findings demonstrate that the 3D microenvironment critically modulates endothelial responses to TGF-{beta} and enables the emergence of vascular phenotypes not captured in 2D systems. This study provides a more physiologically relevant platform to investigate endothelial dysfunction and vascular remodeling.

bioengineering↗

bioRxiv2024

Tumor-microvessel on-a-chip reveals sequential intravasation cascade of cancer cell clusters

Circulating tumor cell (CTC) clusters are often detected in blood samples of patients with high-grade tumor and are associated with tumor metastasis and poor prognosis. However, the underlying mechanisms by which CTC clusters are released from primary tumors beyond blood vessel barriers remain unclear. In this study, a three-dimensional (3D) in vitro culture system is developed to visualize tumor intravasation by positioning tumor organoids with distinct genetic backgrounds to surround microvessels. We visualized tumor intravasation in a cluster unit, including collective migration in the collagen gel, vessel co-option, and the release of CTC clusters as one of cluster invasion manners yet reported previously. In addition, our results show that both transforming growth factor-{beta} (TGF-{beta}) expression in tumor cells and subsequent induction of activin expression in endothelium are essential for tumor cell intravasation accompanied with endothelial-to-mesenchymal transition (EndoMT) in microvessels. Our 3D in vitro system can be used to develop therapeutic strategies for tumor metastasis by targeting CTC clusters.

cancer biology↗

bioRxiv2023

Dendritic, delayed, and stochastic CaMKII activation underlies behavioral time scale plasticity in CA1 synapses

Behavioral time scale plasticity (BTSP), is a form of non-Hebbian plasticity induced by integrating pre- and postsynaptic components separated by behavioral time scale (seconds). BTSP in the hippocampal CA1 neurons underlies place cell formation. However, the molecular mechanisms underlying this behavioral time scale (eligibility trace) and synapse specificity are unknown. CaMKII can be activated in a synapse-specific manner and remain active for a few seconds, making it a compelling candidate for the eligibility trace during BTSP. Here, we show that BTSP can be induced in a single dendritic spine using 2-photon glutamate uncaging paired with postsynaptic current injection temporally separated by behavioral time scale. Using an improved CaMKII sensor, we saw no detectable CaMKII activation during this BTSP induction. Instead, we observed a dendritic, delayed, and stochastic CaMKII activation (DDSC) associated with Ca2+ influx and plateau 20-40 s after BTSP induction. DDSC requires both pre-and postsynaptic activity, suggesting that CaMKII can integrate these two signals. Also, optogenetically blocking CaMKII 30 s after the BTSP protocol inhibited synaptic potentiation, indicating that DDSC is an essential mechanism of BTSP. IP3-dependent intracellular Ca2+ release facilitates both DDSC and BTSP. Thus, our study suggests that the non-synapse specific CaMKII activation provides an instructive signal with an extensive time window over tens of seconds during BTSP.

neuroscience↗

bioRxiv2023

Calcium transients trigger switch-like discharge of prostaglandin E2 (PGE2) in an ERK-dependent manner

Prostaglandin E2 (PGE2) is a key player in a plethora of physiological and pathological events. Nevertheless, little is known about the dynamics of PGE2 secretion from a single cell and its effect on the neighboring cells. Here, by observing confluent Madin-Darby canine kidney (MDCK) epithelial cells expressing fluorescent biosensors we demonstrate that calcium transients in a single cell cause PGE2-mediated radial spread of PKA activation (RSPA) in neighboring cells. By in vivo imaging, RSPA was also observed in the basal layer of the mouse epidermis. Experiments with an optogenetic tool revealed a switch-like PGE2 discharge in response to the increasing cytoplasmic Ca2+ concentrations. The cell density of MDCK cells correlated with the frequencies of calcium transients and the following RSPA. The extracellular signal-regulated kinase (ERK) activation also enhanced the frequency of RSPA in MDCK and in vivo. Thus, the PGE2 discharge is regulated temporally by calcium transients and ERK activity.

cell biology↗

bioRxiv2022

Neurovascular Uncoupling: Multimodal Imaging Delineates the Acute Effects of MDMA

Psychedelic compounds have attracted increasing interest in recent years due to their therapeutic potential for psychiatric disorders. Methylenedioxymethamphetamine (MDMA) is currently being investigated in clinical trials to treat post-traumatic stress disorder. To understand the acute effects of psychedelic drugs in vivo, functional MR imaging (fMRI) has been widely used in recent years. Notably, fMRI studies have shown that MDMA leads to inhibition of brain activity, challenging earlier hypotheses indicating mainly excitatory effects. However, interpretation of hemodynamic changes induced by psychedelics is challenging because of the potent vascular effects associated with this class of substances. Therefore, this study aimed to investigate the acute effects of MDMA using simultaneous positron emission tomography (PET)/fMRI in rats. For this purpose, hemodynamic changes measured by BOLD-fMRI were related to alterations in glucose utilization and serotonin transporter (SERT) occupancy, investigated using [18F]FDG functional PET (fPET) and [11C]DASB PET. We demonstrate that MDMA induces global hemodynamic decreases accompanied by localized metabolic increases. Elevated metabolism was found primarily in limbic projection areas involved in emotion processing. Concurrent BOLD-fMRI decreases, also found in extracerebral areas, indicate that the BOLD-fMRI reductions observed in the brain are of vascular, non-neuronal origin. We further show that higher SERT occupancy strongly correlates with regional BOLD-fMRI reductions. Therefore, increased serotonin levels induced by SERT blockage may cause a neurovascular uncoupling. Correct understanding of the in vivo mechanism of MDMA not only supports ongoing research but also warrants a reassessment of previous studies on neuronal effects of psychedelics relying on neurovascular coupling.

neuroscience↗

bioRxiv2020

Trk Agonist Drugs Rescue Noise-Induced Hidden Hearing Loss

TrkB agonist drugs are shown here to have a significant effect on the regeneration of afferent cochlear synapses after noise-induced synaptopathy. The effects were consistent with regeneration of cochlear synapses that we observed in vitro after synaptic loss due to kainic acid-induced glutamate toxicity and were elicited by administration of TrkB agonists, amitriptyline and 7,8-dihydroxyflavone, directly into the cochlea via the posterior semicircular canal 48 h after exposure to noise. Synaptic counts at the inner hair cell and wave 1 amplitudes in the ABR were partially restored 2 weeks after drug treatment. Effects of amitriptyline on wave 1 amplitude and afferent auditory synapse numbers in noise-exposed ears after systemic (as opposed to local) delivery were profound and long-lasting; synapses in the treated animals remained intact one year after the treatment. However, the effect of systemically delivered amitriptyline on synaptic rescue was dependent on dose and the time window of administration: it was only effective when given before noise exposure at the highest injected dose. The long-lasting effect and the efficacy of post-exposure treatment indicate a potential broad application for the treatment of synaptopathy, which often goes undetected until well after the original damaging exposure(s).

neuroscience↗

bioRxiv2020

An Antibody to RGMa Promotes Regeneration of Cochlear Synapses after Noise Exposure

Auditory neuropathy is caused by the loss of afferent input to the brainstem via the components of the neural pathway comprising inner hair cells and the first order neurons of the spiral ganglion. Recent work has identified the synapse between cochlear primary afferent neurons and sensory hair cells as a particularly vulnerable component of this pathway. Loss of these synapses due to noise exposure or aging results in the pathology identified as hidden hearing loss, an initial stage of cochlear dysfunction that goes undetected in standard hearing tests. We show here that repulsive axonal guidance molecule a (RGMa) acts to prevent regrowth and synaptogenesis of peripheral auditory nerve fibers with inner hair cells. Treatment of noise-exposed animals with an anti-RGMa blocking antibody regenerated inner hair cell synapses and resulted in recovery of wave-I amplitude of the auditory brainstem response, indicating effective reversal of synaptopathy.

neuroscience↗