| First Author | Geng J | Year | 2022 |
| Journal | Elife | Volume | 11 |
| PubMed ID | 36196992 | Mgi Jnum | J:370309 |
| Mgi Id | MGI:7387759 | Doi | 10.7554/eLife.76691 |
| Citation | Geng J, et al. (2022) Chronic Ca(2+) imaging of cortical neurons with long-term expression of GCaMP-X. Elife 11 |
| abstractText | Dynamic Ca(2+) signals reflect acute changes in membrane excitability, and also mediate signaling cascades in chronic processes. In both cases, chronic Ca(2+) imaging is often desired, but challenged by the cytotoxicity intrinsic to calmodulin (CaM)-based GCaMP, a series of genetically-encoded Ca(2+) indicators that have been widely applied. Here, we demonstrate the performance of GCaMP-X in chronic Ca(2+) imaging of cortical neurons, where GCaMP-X by design is to eliminate the unwanted interactions between the conventional GCaMP and endogenous (apo)CaM-binding proteins. By expressing in adult mice at high levels over an extended time frame, GCaMP-X showed less damage and improved performance in two-photon imaging of sensory (whisker-deflection) responses or spontaneous Ca(2+) fluctuations, in comparison with GCaMP. Chronic Ca(2+) imaging of one month or longer was conducted for cultured cortical neurons expressing GCaMP-X, unveiling that spontaneous/local Ca(2+) transients progressively developed into autonomous/global Ca(2+) oscillations. Along with the morphological indices of neurite length and soma size, the major metrics of oscillatory Ca(2+), including rate, amplitude and synchrony were also examined. Dysregulations of both neuritogenesis and Ca(2+) oscillations became discernible around 2-3 weeks after virus injection or drug induction to express GCaMP in newborn or mature neurons, which were exacerbated by stronger or prolonged expression of GCaMP. In contrast, neurons expressing GCaMP-X were significantly less damaged or perturbed, altogether highlighting the unique importance of oscillatory Ca(2+) to neural development and neuronal health. In summary, GCaMP-X provides a viable solution for Ca(2+) imaging applications involving long-time and/or high-level expression of Ca(2+) probes. |
