Time Course Transcriptomics indentifies Storkhead Box 2 as a novel modulator in TGFb Signaling
Open access
Author
Date
2019Type
- Doctoral Thesis
ETH Bibliography
yes
Altmetrics
Abstract
Mammalian embryonic development is one of the most fascinating topics to investigate and has baffled mankind for centuries. The equally complex and beautiful process by which a unicellular zygote develops over time to a full-grown organism with diverse organs and tissues is governed by the intricate interplay of a plethora of signaling mechanisms. Shedding light on these processes and interactions will not only help us find solutions for debilitating diseases but also understand our origin a bit better.
Human embryonic stem cells present a great tool to study the complex processes involved in maintaining pluripotency and early cell fate commitment. In this thesis, I utilized comprehensive time-course transcriptomics in human embryonic stem cells to identify novel effectors of Transforming Growth Factor β (TGFβ) and Fibroblast Growth Factor (FGF) signaling pathways, which are central to human development. Integrating raw RNA-seq data with ChIP-Seq and proteomic data as well as literature research lead to the selection of Storkhead Box 2 (STOX2) as a prime candidate for follow-up mechanistic investigation.
The expression of this vastly understudied gene is heavily downregulated upon TGFβ inhibition in stem cells. We were able to show that this is most likely due to direct binding of SMAD transcription factors to regulatory sequences of the gene. In gene suppression studies we were able to show that loss of STOX2 leads to decreased expression of TGFβ targets. It does so likely by physically interacting with the SMAD complex and regulating its stability. The fact that STOX2 is not only a target of TGFβ signaling but also directly interacts in the pathway itself classifies it as a feedback loop. Immunofluoresence and subcellular fractionation show that, surprisingly, this interaction seems to take place primarily in the cytoplasm of human pluripotent stem cells.
However, upon differentiation the cellular role of STOX2 seems to change. Not only does its expression increase dramatically during neuroectoderm differentiation, without any input from TGFβ signaling, STOX2 also translocates to nucleus in this context where it takes on another role to possibly act as transcription factor. Depletion of STOX2 during neuroectoderm differentiation leads to a concomitant decrease of important neural markers such as SOX1 and PAX6.
This work presents the first ever mechanistic investigation of STOX2, describes its role in TGFβ signaling during pluripotency and attributes a role during neural differentiation. It lays the foundation for future studies to define the dual roles of STOX2 even more closely. Manipulation of STOX2 may one day even help target TGFβ signaling in disease context or improve existing differentiation protocols. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000340896Publication status
publishedExternal links
Search print copy at ETH Library
Contributors
Examiner: Wutz, Anton
Examiner: Werner, Sabine
Examiner: Constam, Daniel
Examiner: Beyer, Tobias Andreas
Publisher
ETH ZurichSubject
TGF beta; Stem cells; Development; SIGNALING; MOLECULAR BIOLOGYOrganisational unit
03978 - Wutz, Anton / Wutz, Anton
More
Show all metadata
ETH Bibliography
yes
Altmetrics