@article{vomDahlMuellerBerishaetal.2022,
  author    = {vom Dahl, Christian and M{\"u}ller, Christoph Emanuel and Berisha, Xhevat and Nagel, Georg and Zimmer, Thomas},
  title     = {Coupling the cardiac voltage-gated sodium channel to channelrhodopsin-2 generates novel optical switches for action potential studies},
  series = {Membranes},
  volume    = {12},
  journal   = {Membranes},
  number    = {10},
  issn      = {2077-0375},
  doi       = {10.3390/membranes12100907},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-288228},
  year      = {2022},
  abstract  = {Voltage-gated sodium (Na\(^+\)) channels respond to short membrane depolarization with conformational changes leading to pore opening, Na\(^+\) influx, and action potential (AP) upstroke. In the present study, we coupled channelrhodopsin-2 (ChR2), the key ion channel in optogenetics, directly to the cardiac voltage-gated Na\(^+\) channel (Na\(_v\)1.5). Fusion constructs were expressed in Xenopus laevis oocytes, and electrophysiological recordings were performed by the two-microelectrode technique. Heteromeric channels retained both typical Na\(_v\)1.5 kinetics and light-sensitive ChR2 properties. Switching to the current-clamp mode and applying short blue-light pulses resulted either in subthreshold depolarization or in a rapid change of membrane polarity typically seen in APs of excitable cells. To study the effect of individual K\(^+\) channels on the AP shape, we co-expressed either K\(_v\)1.2 or hERG with one of the Na\(_v\)1.5-ChR2 fusions. As expected, both delayed rectifier K\(^+\) channels shortened AP duration significantly. K\(_v\)1.2 currents remarkably accelerated initial repolarization, whereas hERG channel activity efficiently restored the resting membrane potential. Finally, we investigated the effect of the LQT3 deletion mutant ΔKPQ on the AP shape and noticed an extremely prolonged AP duration that was directly correlated to the size of the non-inactivating Na\(^+\) current fraction. In conclusion, coupling of ChR2 to a voltage-gated Na\(^+\) channel generates optical switches that are useful for studying the effect of individual ion channels on the AP shape. Moreover, our novel optogenetic approach provides the potential for an application in pharmacology and optogenetic tissue-engineering.},
  language  = {en}
}
@article{JonesHuangHedrichetal.2022,
  author    = {Jones, Jeffrey J. and Huang, Shouguang and Hedrich, Rainer and Geilfus, Christoph-Martin and Roelfsema, M. Rob G.},
  title     = {The green light gap: a window of opportunity for optogenetic control of stomatal movement},
  series = {New Phytologist},
  volume    = {236},
  journal   = {New Phytologist},
  number    = {4},
  doi       = {10.1111/nph.18451},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293724},
  pages     = {1237 -- 1244},
  year      = {2022},
  abstract  = {Green plants are equipped with photoreceptors that are capable of sensing radiation in the ultraviolet-to-blue and the red-to-far-red parts of the light spectrum. However, plant cells are not particularly sensitive to green light (GL), and light which lies within this part of the spectrum does not efficiently trigger the opening of stomatal pores. Here, we discuss the current knowledge of stomatal responses to light, which are either provoked via photosynthetically active radiation or by specific blue light (BL) signaling pathways. The limited impact of GL on stomatal movements provides a unique option to use this light quality to control optogenetic tools. Recently, several of these tools have been optimized for use in plant biological research, either to control gene expression, or to provoke ion fluxes. Initial studies with the BL-activated potassium channel BLINK1 showed that this tool can speed up stomatal movements. Moreover, the GL-sensitive anion channel GtACR1 can induce stomatal closure, even at conditions that provoke stomatal opening in wild-type plants. Given that crop plants in controlled-environment agriculture and horticulture are often cultivated with artificial light sources (i.e. a combination of blue and red light from light-emitting diodes), GL signals can be used as a remote-control signal that controls stomatal transpiration and water consumption.},
  language  = {en}
}