@phdthesis{Kurz2022,
  author    = {Kurz, Hendrikje},
  title     = {Regulation of ion conductance and cAMP/cGMP concentration in megakaryocytes by light},
  doi       = {10.25972/OPUS-21694},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-216947},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Platelets play an essential role in haemostasis. Through granule secretion of second wave mediators and aggregation, they secure vascular integrity. Due to incorrect activation, platelet aggregation and subsequent thrombus formation can cause blood vessel occlusion, leading to ischemia. Patients with defects in platelet production have a low platelet count (thrombocytopenia), which can cause an increased bleeding risk. In vitro platelet generation is still in its development phase. So far, no convincing results have been obtained. For this reason, the health care system still depends on blood donors. Platelets are produced by bone marrow megakaryocytes (MKs), which extend long cytoplasmic protrusions, designated proplatelets, into sinusoidal blood vessels. Due to shear forces, platelets are then released into the bloodstream. The molecular mechanisms underlying platelet production are still not fully understood. However, a more detailed insight of this biological process is necessary to improve the in vitro generation of platelets and to optimise treatment regimens of patients. Optogenetics is defined as "light-modulation of cellular activity or of animal behaviour by gene transfer of photo-sensitive proteins". Optogenetics has had a big impact on neuroscience over the last decade. The use of channelrhodopsin 2 (ChR2), a light-sensitive cation channel, made it possible to stimulate neurons precisely and minimally invasive for the first time. Recent developments in the field of optogenetics intend to address a broader scope of cellular and molecular biology. The aim of this thesis is to establish optogenetics in the field of MK research in order to precisely control and manipulate MK differentiation. An existing "optogenetic toolbox" was used, which made it possible to light-modulate the cellular concentration of specific signalling molecules and ion conductance in MKs. Expression of the bacterial photoactivated adenylyl cyclase (bPAC) resulted in a significant increase in cAMP concentration after 5 minutes of illumination. Similarly, intracellular cGMP concentrations in MKs expressing photoactivated guanylyl cyclase (BeCyclop) were elevated. Furthermore, proplatelet formation of MKs expressing the light-sensitive ion channels ChR2 and anion channelrhodopsin (ACR) was altered in a light-dependent manner. These results show that MK physiology can be modified by optogenetic approaches. This might help shed new light on the underlying mechanisms of thrombopoiesis.},
  subject      = {Optogenetik},
  language  = {en}
}