Monitoring AKT activity and targeting in live tissue and disease contexts using a real-time Akt-FRET biosensor mouse

Aberrant AKT activation occurs in a number of cancers, metabolic syndrome, and immune disorders, making it an important target for the treatment of many diseases. To monitor spatial and temporal AKT activity in a live setting, we generated an Akt-FRET biosensor mouse that allows longitudinal assessment of AKT activity using intravital imaging in conjunction with image stabilization and optical window technology. We demonstrate the sensitivity of the Akt-FRET biosensor mouse using various cancer models and verify its suitability to monitor response to drug targeting in spheroid and organotypic models. We also show that the dynamics of AKT activation can be monitored in real time in diverse tissues, including in individual islets of the pancreas, in the brown and white adipose tissue, and in the skeletal muscle. Thus, the Akt-FRET biosensor mouse provides an important tool to study AKT dynamics in live tissue contexts and has broad preclinical applications.

Optimizing metastatic-cascade-dependent Rac1 targeting in breast cancer: Guidance using optical window intravital FRET imaging

Assessing drug response within live native tissue provides increased fidelity with regards to optimizing efficacy while minimizing off-target effects. Here, using longitudinal intravital imaging of a Rac1-Förster resonance energy transfer (FRET) biosensor mouse coupled with in vivo photoswitching to track intratumoral movement, we help guide treatment scheduling in a live breast cancer setting to impair metastatic progression. We uncover altered Rac1 activity at the center versus invasive border of tumors and demonstrate enhanced Rac1 activity of cells in close proximity to live tumor vasculature using optical window imaging. We further reveal that Rac1 inhibition can enhance tumor cell vulnerability to fluid-flow-induced shear stress and therefore improves overall anti-metastatic response to therapy during transit to secondary sites such as the lung. Collectively, this study demonstrates the utility of single-cell intravital imaging in vivo to demonstrate that Rac1 inhibition can reduce tumor progression and metastases in an autochthonous setting to improve overall survival.

Off-line learning in a rhythmic bimanual task: early feedback dependency is reduced over wakefulness

Research has supported two distinct forms of motor skill consolidation that can occur between practice sessions: (1) off-line learning, and (2) memory stabilization. Off-line learning describes performance improvement between practice sessions that is above the gain observed at the end of practice, while memory stabilization describes a gain in performance that is maintained between practice sessions. This study used a Lissajous plot to provide concurrent feedback to train participants to produce a 90° relative phase between the index fingers (flexion/extension motion). Significant improvements in performance emerged after ten trials (5 min) of practice. At the end of training, participants were divided into two delay interval groups before retesting, 2-h and 6-h. The retesting session started with participants performing an interference task (10 trials, 5 min) that required training on a 45° relative phase between the fingers with concurrent feedback from the Lissajous plot. When training with the interference task was completed participants were retested with the 90° relative phase without the Lissajous plot feedback. In the retest of the 90° pattern, a performance loss was found in the 2-h delay group, whereas the 6-h delay group maintained the end of practice performance level. Maintenance of the same level of performance without the Lissajous plot represents memory stabilization of the initially trained 90° pattern. The findings are discussed within the context of current positions regarding procedural consolidation and the coordination dynamics framework wherein action and perception are linked through the informational nature of relative phase.