Zur Kurzanzeige

Cellular stress induces RIS dependent sleep and ALA dependent sedation via EGF receptor signaling in Caenorhabditis elegans

dc.contributor.advisorBringmann, Henrik Prof. Dr.
dc.contributor.authorKonietzka, Jan
dc.date.accessioned2019-07-15T09:06:35Z
dc.date.available2019-07-15T09:06:35Z
dc.date.issued2019-07-15
dc.identifier.urihttp://hdl.handle.net/21.11130/00-1735-0000-0003-C166-0
dc.identifier.urihttp://dx.doi.org/10.53846/goediss-7558
dc.language.isoengde
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subject.ddc570de
dc.titleCellular stress induces RIS dependent sleep and ALA dependent sedation via EGF receptor signaling in Caenorhabditis elegansde
dc.typedoctoralThesisde
dc.contributor.refereeHeinrich, Ralf Prof. Dr.
dc.date.examination2019-07-05
dc.description.abstractengWhy do we sleep? This question is still unsolved, although sleep is such a fundamental behavioral state in all organism with a nervous system. Several physiological mechanisms, like memory consolidation, metabolic waste clearance, or immune system boosting, depend on sleep but none was sufficient to answer yet, why our consciousness has to shut off every night. The nematode and model organism Caenorhabditis elegans has a minimalistic nervous system of exactly 302 neurons. Still, it provides three different types of sleep, which are linked to either-or one of two sleep neurons. The sleep-active neuron RIS controls developmentally-regulated lethargus sleep and environment-stimulated L1 arrest sleep. Stress-induced sleep (SIS) depends on the interneuron ALA. The clear structure of the nervous system, next to the straightforward genetic accessibility of C. elegans, made it an easy choice to use the worms for exploring sleep on a molecular level. To investigate what defines RIS and ALA on the molecular level, I obtained different transcriptomes for both neurons. I got one transcriptome, which was based on RNA sequencing of fluorescence-activated cell sorted (FACS) RIS neurons. Additionally, Cao et al. (2018) used single-cell combinatorial indexing RNA sequencing to publish a data set of 42’035 single cell transcriptomes, spanning all C. elegans L2 cells. From this data set, clusters representing RIS and ALA could be identified and used for the generation of transcriptomes for both cells, respectively. The transcriptomes provided me with genes enriched in RIS, which were potentially important in sleep control in this neuron. I used mutated alleles of these genes for a behavioral sleep screen. A nonsense-allele of the invertebrate-type lysozyme ilys-4 and a gain-of-function allele of the epidermal growth factor receptor (EGFR) let-23 caused worms to sleep more in L1 arrest. Both were known to express in ALA, but I was able to confirm their additional expression in RIS via fluorescent reporters. I also showed the let- 23(gf) phenotype mainly depends on RIS. SIS was known to be mediated via LET-23 in ALA. I used genetic ablations of ALA and RIS, and a RIS-specific knock-out of let-23 to demonstrate that SIS is also highly vi Introduction dependent on LET-23 signaling in RIS. Calcium imaging revealed that ALA activates broadly over the time span of SIS, while RIS activity correlates with individual sleep bouts of SIS. This is likely mediated via EGF signaling in ALA and RIS, as overexpression of EGF activated both neurons and caused movement quiescence of the worms. Next, I used optogenetic manipulation to show that ALA is able to activate RIS. This may function to some extent via the ALA neuropeptides encoded by flp-24, as shown in an overexpression experiment. I could confirm that worms survival after cellular stress is affected by ALA-induced sedation, but discovered survival does not depend on the RIS-induced sleep bouts. In this thesis, I showed that SIS depends on EGF receptor signaling in RIS, besides the known pathway in ALA. RIS seems to be the major controller of sleep in the worm, as I now discovered that it is involved in all types of sleep in C. elegans. Furthermore, I demonstrated that stress-induced EGF receptor signaling acts parallel in ALA and RIS, which inherit different mechanistic properties and thus provide a discrete response. ALA sedates the worm, while RIS activity causes sleep bouts. This dual system allows the worm to fine-tune the behavioral response to cellular stress. Sedation and sleep representing distinct but interacting pathways in C. elegans might be a general principle, which also holds true in other organisms.de
dc.contributor.coRefereeValerius, Oliver Dr.
dc.contributor.thirdRefereeSchuh, Reinhard Prof. Dr.
dc.contributor.thirdRefereeStumpner, Andreas Prof. Dr.
dc.contributor.thirdRefereeVorbrüggen, Gerd Dr.
dc.subject.engCaenorhabditis elegansde
dc.subject.engSleepde
dc.subject.engEGFde
dc.subject.engRISde
dc.subject.engALAde
dc.subject.engStress-induced sleepde
dc.identifier.urnurn:nbn:de:gbv:7-21.11130/00-1735-0000-0003-C166-0-5
dc.affiliation.instituteGöttinger Graduiertenschule für Neurowissenschaften, Biophysik und molekulare Biowissenschaften (GGNB)de
dc.subject.gokfullBiologie (PPN619462639)de
dc.identifier.ppn1672306566


Dateien

Thumbnail

Das Dokument erscheint in:

Zur Kurzanzeige