@article{ScholzGehringGuanetal.2015, author = {Scholz, Nicole and Gehring, Jennifer and Guan, Chonglin and Ljaschenko, Dmitrij and Fischer, Robin and Lakshmanan, Vetrivel and Kittel, Robert J. and Langenhan, Tobias}, title = {The adhesion GPCR Latrophilin/CIRL shapes mechanosensation}, series = {Cell Reports}, volume = {11}, journal = {Cell Reports}, doi = {10.1016/j.celrep.2015.04.008}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148626}, pages = {866-874}, year = {2015}, abstract = {G-protein-coupled receptors (GPCRs) are typically regarded as chemosensors that control cellular states in response to soluble extracellular cues. However, the modality of stimuli recognized through adhesion GPCR (aGPCR), the second largest class of the GPCR superfamily, is unresolved. Our study characterizes the Drosophila aGPCR Latrophilin/dCirl, a prototype member of this enigmatic receptor class. We show that dCirl shapes the perception of tactile, proprioceptive, and auditory stimuli through chordotonal neurons, the principal mechanosensors of Drosophila. dCirl sensitizes these neurons for the detection of mechanical stimulation by amplifying their input-output function. Our results indicate that aGPCR may generally process and modulate the perception of mechanical signals, linking these important stimuli to the sensory canon of the GPCR superfamily.}, language = {en} } @phdthesis{Ljaschenko2013, author = {Ljaschenko, Dmitrij}, title = {Hebbian plasticity at neuromuscular synapses of Drosophila}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-90465}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2013}, abstract = {Synaptic plasticity determines the development of functional neural circuits. It is widely accepted as the mechanism behind learning and memory. Among different forms of synaptic plasticity, Hebbian plasticity describes an activity-induced change in synaptic strength, caused by correlated pre- and postsynaptic activity. Additionally, Hebbian plasticity is characterised by input specificity, which means it takes place only at synapses, which participate in activity. Because of its correlative nature, Hebbian plasticity suggests itself as a mechanism behind associative learning. Although it is commonly assumed that synaptic plasticity is closely linked to synaptic activity during development, the mechanistic understanding of this coupling is far from complete. In the present study channelrhodopsin-2 was used to evoke activity in vivo, at the glutamatergic Drosophila neuromuscular junction. Remarkably, correlated pre- and postsynaptic stimulation led to increased incorporation of GluR-IIA-type glutamate receptors into postsynaptic receptor fields, thus boosting postsynaptic sensitivity. This phenomenon is input-specific. Conversely, GluR-IIA was rapidly removed from synapses at which neurotransmitter release failed to evoke substantial postsynaptic depolarisation. This mechanism might be responsible to tame uncontrolled receptor field growth. Combining these results with developmental GluR-IIA dynamics leads to a comprehensive physiological concept, where Hebbian plasticity guides growth of postsynaptic receptor fields and sparse transmitter release stabilises receptor fields by preventing overgrowth. Additionally, a novel mechanism of retrograde signaling was discovered, where direct postsynaptic channelrhodopsin-2 based stimulation, without involvement of presynaptic neurotransmitter release, leads to presynaptic depression. This phenomenon is reminiscent of a known retrograde homeostatic mechanism, of inverted polarity, where neurotransmitter release is upregulated, upon reduction of postsynaptic sensitivity.}, subject = {Synapse}, language = {en} }