Biology subjects

Hauserova, A.

Publications and source records attributed to Hauserova, A..

4 recordsLinked to original sources

bioRxiv2025

TEAD4 regulates apical domain homeostasis and cell-positioning to maintain the trophectoderm lineage during preimplantation mouse embryo development.

In mammalian preimplantation embryos, different cell lineages occupy specific niches. For example, the outer trophectoderm (TE) comprises a monolayer of epithelialized cells surrounding the inner-cell mass (ICM) and blastocyst cavity. In mice, TEAD4 is known as a transcription factor that regulates TE-specific genes in a polarity-dependent manner during TE specification. Here we show that it also maintains blastocyst TE integrity, as knocking down (KD) Tead4 via clonal siRNA causes abnormal morphology of outer-cell apical domains, which correlates with the atypical contribution of Tead4-KD cell clones to an enlarged ICM throughout blastocyst maturation; with only minimal feedback on established apical polarity. Light-sheet live-cell embryo imaging reveals these cells either actively migrate into the ICM, sometimes involving apical domain abscission, or are positioned post-division, linking disrupted apical morphology to cell repositioning. RNA-Seq data indicate TEAD4 regulates genes related to the cytoskeleton, particularly actin, and cell adhesion, which we propose are required for the appropriate maintenance of the spatial positioning of specified TE cells in the blastocyst. Indeed, knocking down Tead4 in combination with two identified target genes, the atypical GTPases Rnd1 and Rnd3, partially rescues aberrant outer-to-inner cell allocations but does not influence the onset of apical domain morphological abnormalities. These findings indicate that Tead4 and its regulated transcriptome actively contribute to the maintenance of the outer TE lineage until the peri-implantation stage.

developmental biology↗

bioRxiv2025

Regulation of mouse blastocyst primitive endoderm differentiation by p38-mitogen-activated-kinases (p38-MAPKs) is inner-cell-mass (ICM) autonomous and unrelated to cavity expansion defects in ICM specification.

During early mouse blastocyst ICM maturation, we previously described that pharmacological inhibition of p38-MAPK (p38-MAPKi) significantly impairs primitive endoderm (PrE) differentiation from an initially uncommitted population of ICM cells but does not affect pluripotent epiblast (EPI) specification. A recent report details a positive role for blastocyst cavity expansion in assisting ICM lineage formation and marker gene expression. As p38-MAPKi also results in smaller cavity volumes, we addressed to what extent p38-MAPKi mediated impaired PrE differentiation is driven by ICM autonomous or cavity expansion mechanisms. We compared ICM differentiation phenotypes associated with either chemically inhibited cavity volume expansion and p38-MAPKi, on the individual cell and ICM lineage population levels. Whilst recapitulating previously observed decreases in expression of both EPI and PrE markers, we discovered cavity expansion phenotypes are manifest in impaired numbers of specified EPI and increased numbers of uncommitted cells; rather than impaired PrE differentiation, as observed after p38-MAPKi. Moreover, using both 2D ES-cell and 3D ICM organoid models, we show PrE differentiation is also significantly impaired by p38-MAPKi in the absence of a blastocyst cavity; a result recapitulated in cultured immuno-surgically isolated early blastocyst ICMs, in which an outer PrE and inner EPI population are ordinarily formed. These data confirm the early blastocyst requirement for p38-MAPK activity to permit PrE differentiation from uncommitted ICM progenitors is primarily ICM autonomous rather than caused by impaired cavity expansion.

developmental biology↗

bioRxiv2021

DDX21 is a p38-MAPK sensitive nucleolar protein necessary for mouse preimplantation embryo development and cell-fate specification.

Successful navigation of the mouse preimplantation stages of development, during which three distinct blastocyst lineages are derived, represents a prerequisite for continued development. We previously identified a role for p38-mitogen-activated kinases (p38-MAPK) regulating blastocyst inner cell mass (ICM) cell-fate, specifically primitive endoderm (PrE) differentiation, that is intimately linked to rRNA precursor processing, polysome formation and protein translation regulation. Here, we develop this work by assaying the role of DEAD-box RNA helicase 21 (Ddx21), a known regulator of rRNA processing, in the context of p38-MAPK regulation of preimplantation mouse embryo development. We show nuclear Ddx21 protein is robustly expressed from the 16-cell stage, becoming exclusively nucleolar during blastocyst maturation; a localisation dependent on active p38-MAPK. Efficient siRNA mediated clonal Ddx21 knockdown within developing embryos is associated with profound cell autonomous and non-autonomous proliferation defects and reduced blastocyst volume, by the equivalent peri-implantation blastocyst stage. Moreover, ICM residing Ddx21 knockdown clones express the EPI marker NANOG but rarely express the PrE differentiation marker GATA4. These data contribute extra significance to emerging importance of lineage specific translation regulation, as identified for p38-MAPK, during mouse preimplantation development.

developmental biology↗

bioRxiv2020

p38-MAPK mediated rRNA processing and translation regulation enables PrE differentiation during mouse blastocyst maturation.

Backgroundp38-MAPKs are stress-activated kinases necessary for placental development and nutrient and oxygen transfer during murine post-implantation development. In preimplantation development, p38-MAPK activity is required for blastocyst formation. Additionally, we have previously reported its role in regulating specification of inner cell mass (ICM) towards primitive endoderm (PrE), although a comprehensive mechanistic understanding is currently limited. Adopting live embryo imaging, proteomic and transcriptomic approaches, we report experimental data that directly address this deficit. ResultsChemical inhibition of p38-MAPK activity during blastocyst maturation causes impaired blastocyst cavity expansion, most evident between the third and tenth hours post inhibition onset. We identify an overlapping minimal early blastocyst maturation window of p38-MAPKi inhibition (p38-MAPKi) sensitivity, that is sufficient to impair PrE cell fate by the late blastocyst (E4.5) stage. Comparative proteomic analyses reveal substantial downregulation of ribosomal proteins, the mRNA transcripts of which are also significantly upregulated. Ontological analysis of the differentially expressed transcriptome during this developmental period reveals "translation" related gene transcripts as being most significantly, yet transiently, affected by p38-MAPKi. Moreover, combined assays consistently report concomitant reductions in de novo translation that are associated with accumulation of unprocessed rRNA precursors. Using a phosphoproteomic approach, {+/-} p38-MAPKi, we identified Mybpp1a, an rRNA transcription and processing regulator gene, as a potential p38-MAPK effector. We report that siRNA mediated clonal knockdown of Mybpp1a is associated with significantly diminished PrE contribution. Lastly, we show that defective PrE specification caused by p38-MAPKi (but not MEK/ERK signalling inhibition) can be partially rescued by activating the archetypal mTOR mediated translation regulatory pathway. ConclusionsActivated p38-MAPK controls blastocyst maturation in an early and distinctly transient developmental window by regulating gene functionalities related to translation, that creates a permissive environment for appropriate specification of ICM cell fate.

developmental biology↗