@article{19404,
  abstract     = {Cell migration is a fundamental process during embryonic development. Most studies in vivo have focused on the migration of cells using the extracellular matrix (ECM) as their substrate for migration. In contrast, much less is known about how cells migrate on other cells, as found in early embryos when the ECM has not yet formed. Here, we show that lateral mesendoderm (LME) cells in the early zebrafish gastrula use the ectoderm as their substrate for migration. We show that the lateral ectoderm is permissive for the animal-pole-directed migration of LME cells, while the ectoderm at the animal pole halts it. These differences in permissiveness depend on the lateral ectoderm being more cohesive than the animal ectoderm, a property controlled by bone morphogenetic protein (BMP) signaling within the ectoderm. Collectively, these findings identify ectoderm tissue cohesion as one critical factor in regulating LME migration during zebrafish gastrulation.},
  author       = {Tavano, Ste and Brückner, David and Tasciyan, Saren and Tong, Xin and Kardos, Roland and Schauer, Alexandra and Hauschild, Robert and Heisenberg, Carl-Philipp J},
  issn         = {2211-1247},
  journal      = {Cell Reports},
  number       = {3},
  publisher    = {Elsevier},
  title        = {{BMP-dependent patterning of ectoderm tissue material properties modulates lateral mesendoderm cell migration during early zebrafish gastrulation}},
  doi          = {10.1016/j.celrep.2025.115387},
  volume       = {44},
  year         = {2025},
}

@article{15048,
  abstract     = {Embryogenesis results from the coordinated activities of different signaling pathways controlling cell fate specification and morphogenesis. In vertebrate gastrulation, both Nodal and BMP signaling play key roles in germ layer specification and morphogenesis, yet their interplay to coordinate embryo patterning with morphogenesis is still insufficiently understood. Here, we took a reductionist approach using zebrafish embryonic explants to study the coordination of Nodal and BMP signaling for embryo patterning and morphogenesis. We show that Nodal signaling triggers explant elongation by inducing mesendodermal progenitors but also suppressing BMP signaling activity at the site of mesendoderm induction. Consistent with this, ectopic BMP signaling in the mesendoderm blocks cell alignment and oriented mesendoderm intercalations, key processes during explant elongation. Translating these ex vivo observations to the intact embryo showed that, similar to explants, Nodal signaling suppresses the effect of BMP signaling on cell intercalations in the dorsal domain, thus allowing robust embryonic axis elongation. These findings suggest a dual function of Nodal signaling in embryonic axis elongation by both inducing mesendoderm and suppressing BMP effects in the dorsal portion of the mesendoderm.},
  author       = {Schauer, Alexandra and Pranjic-Ferscha, Kornelija and Hauschild, Robert and Heisenberg, Carl-Philipp J},
  issn         = {1477-9129},
  journal      = {Development},
  number       = {4},
  pages        = {1--18},
  publisher    = {The Company of Biologists},
  title        = {{Robust axis elongation by Nodal-dependent restriction of BMP signaling}},
  doi          = {10.1242/dev.202316},
  volume       = {151},
  year         = {2024},
}

@article{18940,
  abstract     = {BMP signaling has a conserved function in patterning the dorsal-ventral body axis in Bilateria and the directive axis in anthozoan cnidarians. So far, cnidarian studies have focused on the role of different BMP signaling network components in regulating pSMAD1/5 gradient formation. Much less is known about the target genes downstream of BMP signaling. To address this, we generated a genome-wide list of direct pSMAD1/5 target genes in the anthozoan <jats:italic>Nematostella vectensis</jats:italic>, several of which were conserved in <jats:italic>Drosophila</jats:italic> and <jats:italic>Xenopus</jats:italic>. Our ChIP-seq analysis revealed that many of the regulatory molecules with documented bilaterally symmetric expression in <jats:italic>Nematostella</jats:italic> are directly controlled by BMP signaling. We identified several so far uncharacterized BMP-dependent transcription factors and signaling molecules, whose bilaterally symmetric expression may be indicative of their involvement in secondary axis patterning. One of these molecules is <jats:italic>zswim4-6</jats:italic>, which encodes a novel nuclear protein that can modulate the pSMAD1/5 gradient and potentially promote BMP-dependent gene repression.},
  author       = {Knabl, Paul and Schauer, Alexandra and Pomreinke, Autumn P and Zimmermann, Bob and Rogers, Katherine W and Čapek, Daniel and Müller, Patrick and Genikhovich, Grigory},
  issn         = {2050-084X},
  journal      = {eLife},
  publisher    = {eLife Sciences Publications},
  title        = {{Analysis of SMAD1/5 target genes in a sea anemone reveals ZSWIM4-6 as a novel BMP signaling modulator}},
  doi          = {10.7554/elife.80803},
  volume       = {13},
  year         = {2024},
}

@phdthesis{12891,
  abstract     = {The tight spatiotemporal coordination of signaling activity determining embryo
patterning and the physical processes driving embryo morphogenesis renders
embryonic development robust, such that key developmental processes can unfold
relatively normally even outside of the full embryonic context. For instance, embryonic
stem cell cultures can recapitulate the hallmarks of gastrulation, i.e. break symmetry
leading to germ layer formation and morphogenesis, in a very reduced environment.
This leads to questions on specific contributions of embryo-specific features, such as
the presence of extraembryonic tissues, which are inherently involved in gastrulation
in the full embryonic context. To address this, we established zebrafish embryonic
explants without the extraembryonic yolk cell, an important player as a signaling
source and for morphogenesis during gastrulation, as a model of ex vivo development.
We found that dorsal-marginal determinants are required and sufficient in these
explants to form and pattern all three germ layers. However, formation of tissues,
which require the highest Nodal-signaling levels, is variable, demonstrating a
contribution of extraembryonic tissues for reaching peak Nodal signaling levels.
Blastoderm explants also undergo gastrulation-like axis elongation. We found that this
elongation movement shows hallmarks of oriented mesendoderm cell intercalations
typically associated with dorsal tissues in the intact embryo. These are disrupted by
uniform upregulation of BMP signaling activity and concomitant explant ventralization,
suggesting that tight spatial control of BMP signaling is a prerequisite for explant
morphogenesis. This control is achieved by Nodal signaling, which is critical for
effectively downregulating BMP signaling in the mesendoderm, highlighting that Nodal
signaling is not only directly required for mesendoderm cell fate specification and
morphogenesis, but also by maintaining low levels of BMP signaling at the dorsal side.
Collectively, we provide insights into the capacity and organization of signaling and
morphogenetic domains to recapitulate features of zebrafish gastrulation outside of
the full embryonic context.},
  author       = {Schauer, Alexandra},
  issn         = {2663-337X},
  pages        = {190},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{Mesendoderm formation in zebrafish gastrulation: The role of extraembryonic tissues}},
  doi          = {10.15479/at:ista:12891},
  year         = {2023},
}

@article{8966,
  abstract     = {During development, a single cell is transformed into a highly complex organism through progressive cell division, specification and rearrangement. An important prerequisite for the emergence of patterns within the developing organism is to establish asymmetries at various scales, ranging from individual cells to the entire embryo, eventually giving rise to the different body structures. This becomes especially apparent during gastrulation, when the earliest major lineage restriction events lead to the formation of the different germ layers. Traditionally, the unfolding of the developmental program from symmetry breaking to germ layer formation has been studied by dissecting the contributions of different signaling pathways and cellular rearrangements in the in vivo context of intact embryos. Recent efforts, using the intrinsic capacity of embryonic stem cells to self-assemble and generate embryo-like structures de novo, have opened new avenues for understanding the many ways by which an embryo can be built and the influence of extrinsic factors therein. Here, we discuss and compare divergent and conserved strategies leading to germ layer formation in embryos as compared to in vitro systems, their upstream molecular cascades and the role of extrinsic factors in this process.},
  author       = {Schauer, Alexandra and Heisenberg, Carl-Philipp J},
  issn         = {0012-1606},
  journal      = {Developmental Biology},
  keywords     = {Developmental Biology, Cell Biology, Molecular Biology},
  pages        = {71--81},
  publisher    = {Elsevier},
  title        = {{Reassembling gastrulation}},
  doi          = {10.1016/j.ydbio.2020.12.014},
  volume       = {474},
  year         = {2021},
}

@article{7888,
  abstract     = {Embryonic stem cell cultures are thought to self-organize into embryoid bodies, able to undergo symmetry-breaking, germ layer specification and even morphogenesis. Yet, it is unclear how to reconcile this remarkable self-organization capacity with classical experiments demonstrating key roles for extrinsic biases by maternal factors and/or extraembryonic tissues in embryogenesis. Here, we show that zebrafish embryonic tissue explants, prepared prior to germ layer induction and lacking extraembryonic tissues, can specify all germ layers and form a seemingly complete mesendoderm anlage. Importantly, explant organization requires polarized inheritance of maternal factors from dorsal-marginal regions of the blastoderm. Moreover, induction of endoderm and head-mesoderm, which require peak Nodal-signaling levels, is highly variable in explants, reminiscent of embryos with reduced Nodal signals from the extraembryonic tissues. Together, these data suggest that zebrafish explants do not undergo bona fide self-organization, but rather display features of genetically encoded self-assembly, where intrinsic genetic programs control the emergence of order.},
  author       = {Schauer, Alexandra and Nunes Pinheiro, Diana C and Hauschild, Robert and Heisenberg, Carl-Philipp J},
  issn         = {2050-084X},
  journal      = {eLife},
  publisher    = {eLife Sciences Publications},
  title        = {{Zebrafish embryonic explants undergo genetically encoded self-assembly}},
  doi          = {10.7554/elife.55190},
  volume       = {9},
  year         = {2020},
}

@article{7001,
  author       = {Schwayer, Cornelia and Shamipour, Shayan and Pranjic-Ferscha, Kornelija and Schauer, Alexandra and Balda, M and Tada, M and Matter, K and Heisenberg, Carl-Philipp J},
  issn         = {1097-4172},
  journal      = {Cell},
  number       = {4},
  pages        = {937--952.e18},
  publisher    = {Cell Press},
  title        = {{Mechanosensation of tight junctions depends on ZO-1 phase separation and flow}},
  doi          = {10.1016/j.cell.2019.10.006},
  volume       = {179},
  year         = {2019},
}