title: The link between glycolysis and signaling during mouse embryo segmentation
creator: Rada, Jona
subject: ddc-500
subject: 500 Natural sciences and mathematics
subject: ddc-570
subject: 570 Life sciences
description: New phenotypes can arise in organisms as a response to changing environments. Changes  in environmental conditions, such as temperature fluctuations, pressure changes, or nutrient  availability, are translated into cellular processes, thus giving rise to new phenotypes without  affecting the genotype. Metabolism can be a translator of such environmental changes. It is  being recognized more and more how metabolism can not only have a bioenergetic role but  also affect signaling, gene expression, epigenetics, post-translational modifications, etc.  I have conducted this work in mouse embryos, where Hidenobu Miyazawa has observed  a phenotype in developmental timing as a result of changes in glycolytic flux. Previous  data shows that increasing glycolytic flux in the presomitic mesoderm (PSM) slows down  the tempo of the segmentation clock (a molecular clock that controls the patterning of the  PSM). Because of these previous findings, I was interested in investigating the link between  glycolysis and signaling in the PSM.  I addressed the questions in the first part of this work by applying a microfluidics-based  entrainment approach. Entrainment is a fundamental property of oscillating systems, which  occurs when an oscillator adjusts its phase and its period to an external periodic pertur-  bation, thus getting entrained to it. It has been shown before that glucose can entrain the  segmentation clock, so first, I expanded the approach of glycolytic entrainment and tested  which glycolytic metabolites can entrain the segmentation clock. The segmentation clock  consists of an intricate network of different signaling pathways, such as Notch, Wnt, and  FGF. I attempted entrainment of Notch oscillations (which are the core oscillatory compo-  nent of the segmentation clock) with fructose-6-phosphate (F6P), fructose-1,6-bisphosphate  (FBP), and pyruvate. I quantified the efficiency of entrainment by F6P, FBP and pyruvate  by using the entrainment phase and in-phase synchrony as readouts. I identified FBP as a  Zeitgeber (an external cue that synchronizes an organism’s intrinsic clock), which entrained   both Notch and Wnt oscillations based on the predefined criteria. I showed that FBP pulses  change the phase of entrainment when pulses are applied at different periods (detunings).  I saw a difference in timing to entrainment between Wnt and Notch during entrainment  with FBP pulses, hinting at a differential relationship between FBP and these two signaling  pathways. The segmentation clock did not get entrained by pulses of pyruvate. Therefore,  I suggest that the part of glycolysis that is linked to signaling might be confined between  FBP and pyruvate (excluding pyruvate).  Furthermore, I investigated whether glycolysis has a signaling role in the segmentation  clock and how glycolysis is functionally linked to signaling during mouse embryo segmen-  tation. I tried to disentangle the functional link of FBP to signaling by entraining with  combination pulses of FBP and signaling perturbations of Wnt and Notch. By using pre-  dictions from theory of dynamical systems, I showed that FBP functions as a signal in  entraining the segmentation clock, hinting at a role of FBP in the PSM that goes beyond  its bioenergetic function. I made some predictions about the functional link between FBP  and signaling based on the resulting phases of entrainment after applying combined pulses  of FBP and signaling perturbations.  In the second part of this work, I explored the presence of glycolytic oscillations in the PSM  by using Ca2+ oscillations as indirect evidence. I discovered that there are Ca2+ oscillations  present in the PSM, which are induced by glucose and F6P supplementation in the medium,  whereas they are depleted by FBP and pyruvate supplementation. Thus, I gathered some  first evidence, which suggests that it might be worth it to develop FBP sensors in mice in  order to consolidate the presence of glycolytic rhythms in the PSM.
date: 2024
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/35470/1/Thesis_Rada_Final_first_person.pdf
identifier: DOI:10.11588/heidok.00035470
identifier: urn:nbn:de:bsz:16-heidok-354707
identifier:   Rada, Jona  (2024) The link between glycolysis and signaling during mouse embryo segmentation.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/35470/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng