Biology subjects

Takakura, K.

Publications and source records attributed to Takakura, K..

3 recordsLinked to original sources

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

A FRET biosensor, SMART, monitors necroptosis in renal tubular epithelial cells in a cisplatin-induced kidney injury model

Necroptosis is a regulated form of cell death involved in various pathological conditions, including ischemic reperfusion injuries, virus infections, and drug-induced tissue injuries. However, it is not fully understood when and where necroptosis occurs in vivo. We previously generated a Forster resonance energy transfer (FRET) biosensor, termed SMART (the sensor for MLKL activation based on FRET), which specifically monitored necroptosis in human and murine cell lines in vitro. Here, we generated transgenic (Tg) mice that expressed the SMART biosensor in various tissues. SMART monitored necroptosis, but not apoptosis or pyroptosis, in primary cells, including peritoneal macrophages and embryonic fibroblasts. Moreover, the FRET signal was elevated in renal tubular cells of cisplatin-treated SMART Tg mice compared to untreated SMART Tg mice. Together, SMART Tg mice may provide a valuable tool for monitoring necroptosis in different types of cells in vitro and in vivo.

cell biology↗

bioRxiv2020

Intravital imaging reveals cell cycle-dependent satellite cell migration during muscle regeneration.

During muscle regeneration, extracellular signal-regulated kinase (ERK) promotes both proliferation and migration. However, the relationship between proliferation and migration is poorly understood in this context. To elucidate this complex relationship on a physiological level, we established an intravital imaging system for measuring ERK activity, migration speed, and cell-cycle phases in mouse muscle satellite cells. We found that in vivo, ERK was maximally activated in satellite cells two days after injury, and this is then followed by increases in cell number and motility. With limited effects of immediate ERK activity on migration, we hypothesized that ERK increases migration speed in the later phase by promoting cell-cycle progression. Our cell-cycle analysis further revealed that in satellite cells, ERK activity is critical for the G1/S transition, and cells migrate more rapidly in the S/G2 phase three days after injury. Finally, migration speed of satellite cells was suppressed after CDK1/2, but not CDK1, inhibitor treatment, demonstrating a critical role of CDK2 in satellite cell migration. Overall, our study demonstrates that in satellite cells, the ERK-CDK2 axis not only promotes the G1/S transition, but also migration speed, which may provide a novel mechanism for efficient muscle regeneration.

cell biology↗