Biology subjects

Vuoristo, S.

Publications and source records attributed to Vuoristo, S..

6 recordsLinked to original sources

bioRxiv2026

Hsa-miR-92a-3p regulates cell-cycle and signaling programs during human extra-embryonic lineage commitment

MicroRNA (miRNA) levels increase during human embryonic genome activation (EGA) and have been implicated in the first lineage decisions. Re-analyzing single-cell and bulk small RNA-seq (sRNA-seq) from human and mouse embryos, together with new sRNA-seq of naive human embryonic stem cells (hESCs) differentiated into hypoblast-like cells (HLCs) and extra-embryonic mesoderm (EXM)-like cells (EXMCs), we identify hsa-miR-92a-3p as highly expressed from oocyte to morula stage and dynamically regulated during HLC and EXMC formation. Functional inhibition of hsa-miR-92a-3p delays RACL (HLC/EXMC) differentiation, maintains epiblast-like and promotes trophectoderm (TE)-like transcriptional features, and reduces hypoblast and EXM marker acquisition. Transcriptome analyses revealed derepression of hsa-miR-92a-3p targets, including FGF2, and shifts in developmental and cell-cycle programs. The patterns of FGF protein stainings and flow cytometry-based cell-cycle analysis further implicate these pathways in RACL differentiation. Our findings position hsa-miR-92a-3p as a central regulator coordinating signaling and cell-cycle cues during extra embryonic lineage progression.

developmental biology↗

bioRxiv2025

Integrated transcriptomic analysis reveals a metabolically quiescent state and gene expression networks related to intermediate and mature human 8-cell stage embryo resembling cells in vitro

Human early development is challenging to study due to limited samples and cell numbers. The emergence of 8-cell stage embryo-like cells (8CLCs) offers new opportunities to understand embryonic genome activation (EGA) in humans. Our research compares and characterizes 8CLCs from various stem cell-based systems to determine how well these models reflect human early embryonic development. Using single-cell RNA sequencing (scRNA-seq) datasets from multiple studies, we integrated data to identify key gene co-expression modules, transposable element (TE) expression, and biological processes recapitulated in 8CLCs. We identified both mature and intermediate 8CLCs, with the Yoshihara and Mazid datasets best representing 8-cell stage embryos. 8CLCs show quiescence in energy and RNA metabolism, regulation of RNA splicing, and ribosome biogenesis, mirroring human 8-cell stage embryos. Our findings underscore the importance of distinguishing mature 8CLCs from partially reprogrammed cell states to improve their use as models for human EGA, in vitro.

developmental biology↗

bioRxiv2024

Mechano-osmotic signals control chromatin state and fate transitions in pluripotent stem cells

Acquisition of specific cell shapes and morphologies is a central component of cell fate transitions. Although signaling circuits and gene regulatory networks that regulate pluripotent stem cell differentiation have been intensely studied, how these networks are integrated in space and time with morphological transitions and mechanical deformations to control state transitions remains a fundamental open question. Here, we focus on two distinct models of pluripotency, primed pluripotent stem cells and pre-implantation inner cell mass cells of human embryos to discover that cell fate transitions associate with rapid changes in nuclear shape and volume which collectively alter the nuclear mechanophenotype. Mechanistic studies in human induced pluripotent stem cells further reveal that these phenotypical changes and the associated active fluctuations of the nuclear envelope arise from growth factor signaling-controlled changes in chromatin mechanics and cytoskeletal confinement. These collective mechano-osmotic changes trigger global transcriptional repression and a condensation-prone environment that primes chromatin for a cell fate transition by attenuating repression of differentiation genes. However, while this mechano-osmotic chromatin priming has the potential to accelerate fate transitions and differentiation, sustained biochemical signals are required for robust induction of specific lineages. Our findings uncover a critical mechanochemical feedback mechanism that integrates nuclear mechanics, shape and volume with biochemical signaling and chromatin state to control cell fate transition dynamics.

cell biology↗

bioRxiv2021

Transient DUX4 expression induces blastomere-like expression program that is marked by SLC34A2

DUX4 has recently been recognized as a key regulator in human embryonic genome activation (EGA). The exact role of DUX4 in human embryo is still elusive, partly due to the cytotoxicity of persistent DUX4 expression in cellular models. We report here that a transient DUX4 expression in human embryonic stem cells (hESCs) retains cell viability while inducing an EGA-like expression program in a subpopulation of the cells. These cells showed resemblance to 8-cell stage blastomeres and were thus named induced blastomere-like (iBM) cells. Trajectory inference from the single-cell RNA-seq data suggested that the expression profile of these cells progressed in a manner similar to the morula to blastocyst transition in human embryo. Finally, viable iBM cells could be enriched using an antibody against NaPi2b (SLC34A2), paving the way for further experimental approaches. The iBM cells can become a powerful tool to model transcriptional dynamics and regulation during early human embryogenesis.

cell biology↗

bioRxiv2019

DUX4 regulates oocyte to embryo transition in human

During the human oocyte-to-embryo transition, the fertilized oocyte undergoes final maturation and the embryo genome is gradually activated during the first three cell divisions. How this transition is coordinated in humans is largely unknown. We show that the double homeodomain transcription factor DUX4 contributes to this transition. DUX4 knockdown in human zygotes caused insufficient transcriptome reprogramming as observed three days after fertilization. Induced DUX4 expression in human embryonic stem cells activated transcription of thousands of newly identified bi-directional transcripts, including putative enhancers for embryonic genome activation genes such as LEUTX. DUX4 protein interacted with transcriptional modifiers that are known to couple enhancers and promoters. Taken together, our results reveal that DUX4 is a pioneer regulating oocyte-to-embryo transition in human through activation of intergenic genome, especially enhancers, and hence setting the stage for early human embryo development.

developmental biology↗

bioRxiv2019

Complement in human pre-implantation embryos: attack and defense

It is essential for early human life that immunological responses to developing embryos are tightly regulated. An imbalance in the activation and regulation of the human complement system occurs in pregnancy complications, such as pre-eclampsia and recurrent miscarriage. We hereby present the first full analysis of the expression and deposition of complement molecules in human pre-implantation embryos. Thus far, immunological imbalance has been considered in stages of pregnancy following implantation. We here show that complement activation and deposition takes place on developing human embryos already at the pre-implantation stage. Using confocal microscopy, we observed deposition of activation products such as C1q, C3 and C5 on healthy developing embryos, which highlights the need for strict complement regulation. The early embryos express the complement membrane inhibitors CD46, CD55 and CD59 and bind the soluble regulators C4bp and factor H. These findings show that complement targets human embryos, and indicate potential adverse pregnancy outcomes, if regulation of activation fails. In addition, single-cell RNA sequencing of embryos at oocyte, zygote, 4-cell and 8-cell stages showed expression of complement genes, e.g. C1s, C2, C3, C5, factor B and factor D. This shows that the embryonic cells themselves have the capacity to express C3 and C5, which may become activated and function as mediators of cellular signaling. The specific local embryonic expression of complement components, regulators, and deposition of activation products on the surface of embryos suggests that complement has immunoregulatory functions and may impact cellular homeostasis and differentiation at the earliest stage of human life.\n\nStatement of significanceWhile canonical functions of the complement system relate to pathogen-defence, it is known to drive certain immune pathologies. The work here described shows, for the first time, expression and localization of a full range of complement molecules in human pre-implantation embryos. We demonstrate complement attack against early embryos, and show presence of embryonic defence mechanisms. Furthermore, we reveal early embryonic production of complement activators, suggesting non-canonical roles in cell signalling and development. Our findings thus reveal a fundamental role for complement at the earliest stages of human embryogenesis. Our data opens up for future studies into the role of complement, both in relation to infertility and pregnancy complications, as well as basic cellular processes during early human development.

developmental biology↗