Intravital imaging reveals cell cycle-dependent myogenic cell migration during muscle regeneration

Abstract

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 cellcycle phases in mouse muscle satellite cell-derived myogenic cells. We found that in vivo, ERK is maximally activated in myogenic cells two days after injury, and this is then followed by increases in cell number and motility. With limited effects of ERK activity on migration on an acute timescale, we hypothesized that ERK increases migration speed in the later phase by promoting cellcycle progression. Our cell-cycle analysis further revealed that in myogenic cells, ERK activity is critical for G1/S transition, and cells migrate more rapidly in S/G2 phase 3 days after injury. Finally, migration speed of myogenic cells was suppressed after CDK1/2-but not CDK1-inhibitor treatment, demonstrating a critical role of CDK2 in myogenic cell migration. Overall, our study demonstrates that in myogenic cells, the ERK-CDK2 axis promotes not only G1/S transition but also migration, thus providing a novel mechanism for efficient muscle regeneration.

Imaging analysis for muscle stem cells and regeneration

“…After several hours of in vivo imaging of regenerating muscle to monitor the initial response to muscle injury, cell migration, cell division, and cell fusion of MuSCs using two-photon microscopy or standard confocal microscopy. Konagaya et al (2020) utilized an intravital imaging system for measuring migration rate, extracellular signal-regulated kinase (ERK) activity, and cell cycle of MuSCs within mouse TA muscle. Jacobsen et al injected adult mice with fluorescent dextran and performed intravital imaging to assess in vivo microvascular perfusion of the gluteus maximus (GM) muscle.…”

Automatic detection of three cell types in a microscope image based on deep learning

“…In this article, T score was set to 0.01, and the process of parameter selection was described in detail in Section 3.3. When the prediction box was retained, s would be set to G 0 [4], which recorded the confidence value of G 0 . If G was retained, then the G 0 [4] assignment is expressed in Equation ( 13) as:…”

“…When the prediction box was retained, s would be set to G 0 [4], which recorded the confidence value of G 0 . If G was retained, then the G 0 [4] assignment is expressed in Equation ( 13) as:…”

“…Recently, convolutional neural networks (CNNs) are widely used in the field of biomedical image analysis [2, 3]. Therefore, the research based on deep learning for the object detection of human cells provides some new insights into fundamental life sciences and also creates new possibilities in clinical settings, such as applications in prenatal genetic testing or cancer diagnosis [4]. It can help researchers understand the process of cellular action in the human body, and provide valuable assistance to automated technologies for clinical applications [5].…”

Drosophila, an Integrative Model to Study the Features of Muscle Stem Cells in Development and Regeneration

“…Although MuSCs have been extensively studied since their discovery in the early sixties, major gaps still exist in our understanding of their behavior during the early steps of their activation, prior to differentiation. Intravital imaging has proven to be a powerful approach to address such questions [87][88][89]. However, the use of this method in mice models has been constrained both by the complexity of the muscle environment and the long duration of regeneration, which precludes extended live imaging.…”