Unbiased contribution of the first two blastomeres to mouse blastocyst development

MotivationThe identification of heterogeneities in cell populations by utilizing single-cell technologies such as single-cell RNA-Seq, enables inference of cellular development and lineage trees. Several methods have been proposed for such inference from high-dimensional single-cell data. They typically assign each cell to a branch in a differentiation trajectory. However, they commonly assume specific geometries such as tree-like developmental hierarchies and lack statistically sound methods to decide on the number of branching events.ResultsWe present K-Branches, a solution to the above problem by locally fitting half-lines to single-cell data, introducing a clustering algorithm similar to K-Means. These halflines are proxies for branches in the differentiation trajectory of cells. We propose a modified version of the GAP statistic for model selection, in order to decide on the number of lines that best describe the data locally. In this manner, we identify the location and number of subgroups of cells that are associated with branching events and full differentiation, respectively. We evaluate the performance of our method on single-cell RNA-Seq data describing the differentiation of myeloid progenitors during hematopoiesis, single-cell qPCR data of mouse blastocyst development and artificial data.AvailabilityAn R implementation of K-Branches is freely available at https://github.com/theislab/[email protected]

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Notch signaling in mouse blastocyst development and hatching

10.21203/rs.3.rs-22442/v2 ◽

2020 ◽

Author(s):

Mariana Batista ◽

Patrícia Diniz ◽

Ana Torres ◽

Daniel Murta ◽

Luís Lopes-da-Costa ◽

...

Keyword(s):

Protein Expression ◽

Notch Signaling ◽

Gene Transcription ◽

Embryo Culture ◽

Expression Patterns ◽

Mouse Blastocyst ◽

Blastocyst Development ◽

Gene Markers ◽

Signaling Activity ◽

Blastocyst Hatching

Abstract Background Mammalian early embryo development requires a well-orchestrated interplay of cell signaling pathways. Notch is a major regulatory pathway involved in cell-fate determination in embryonic and adult scenarios. However, the role of Notch in embryonic pre-implantation development is controversial. In particular, Notch role on blastocyst development and hatching remains elusive, and a complete picture of the transcription and expression patterns of Notch components during this time-period is not available.Results This study provided a comprehensive view on the dynamics of individual embryo gene transcription and protein expression patterns of Notch components (receptors Notch1-4; ligands Dll1 and Dll4, Jagged1-2; and effectors Hes1-2), and their relationship with transcription of gene markers of pluripotency and differentiation (Sox2, Oct4, Klf4, Cdx2) during mouse blastocyst development and hatching. Transcription of Notch1-2, Jagged1-2 and Hes1 was highly prevalent and dynamic along stages of development, whereas transcription of Notch3-4, Dll4 and Hes2 had a low prevalence among embryos. Transcription levels of Notch1, Notch2, Jagged2 and Hes1 correlated with each other and with those of pluripotency and differentiation genes. Gene transcription was associated to protein expression, except for Jagged2, where high transcription levels in all embryos were not translated into protein. Presence of Notch signaling activity was confirmed through nuclear NICD and Hes1 detection, and downregulation of Hes1 transcription following canonical signaling blockade with DAPT. In vitro embryo culture supplementation with Jagged1 had no effect on embryo developmental kinetics. In contrast, supplementation with Jagged2 abolished Jagged1 transcription, downregulated Cdx2 transcription and inhibited blastocyst hatching. Notch signaling blockade by DAPT downregulated transcription of Sox2, and retarded embryo hatching. Conclusion Transcription of Notch genes showed a dynamic pattern along blastocyst development and hatching. Data confirmed Notch signaling activity, and lead to the suggestion that Notch canonical signaling may be operating through Notch1, Notch3, Jagged1 and Hes1. Embryo culture supplementation with Jagged1 and Jagged2 unveiled a possible regulatory effect between Jagged1, Cdx2 and blastocyst hatching. Overall, results indicate that a deregulation in Notch signaling, either by its over or under-activation, affects blastocyst development and hatching.

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Interaction between inner cell mass and trophectoderm of the mouse blastocyst

Development ◽

10.1242/dev.48.1.109 ◽

1978 ◽

Vol 48 (1) ◽

pp. 109-125

Author(s):

A. J. Copp

Keyword(s):

Inner Cell Mass ◽

Cell Mass ◽

Cell Number ◽

High Rate ◽

Mouse Blastocyst ◽

Blastocyst Development ◽

Trophectoderm Cells ◽

Rate Of Increase ◽

Short Period ◽

Number Increase

Increase in cell number has been compared with mitotic activity in the polar and mural trophectoderm and in the inner cell mass (ICM) of mouse blastocysts. The results indicate that whereas ICM cells divide at a rate which is compatible with the rate of increase of ICM cell number, polar trophectoderm cells divide faster and mural trophectoderm cells slower than can account for their own rates of cell number increase. It is suggested that the ICM induces a high rate of proliferation in the polar trophectoderm and that there is a resulting cell shift from polar to mural regions during blastocyst development. Mural trophectoderm cells close to the ICM divide faster than those farther away, indicating that cells may retain a ‘memory’ of ICM contact for some time after leaving the ICM. There is considerable cell death in the blastocyst, but this is restricted to a short period of time coincident with the appearance of primitive endoderm.

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Three-dimensional cell neighbourhood impacts differentiation in the inner mass cells of the mouse blastocyst

10.1101/159301 ◽

2017 ◽

Cited By ~ 2

Author(s):

Sabine C. Fischer ◽

Elena Corujo-Simón ◽

Joaquín Lilao-Garzón ◽

Ernst H. K. Stelzer ◽

Silvia Muñoz-Descalzo

Keyword(s):

Cell Fate ◽

Inner Cell Mass ◽

Cell Mass ◽

Three Dimensional ◽

Mouse Blastocyst ◽

Blastocyst Development ◽

Cell Position ◽

Fate Decision ◽

Early Mouse ◽

Dimensional Cell

AbstractDuring mammalian blastocyst development, inner cell mass (ICM) cells differentiate into epiblast (Epi) or primitive endoderm (PrE). These two fates are characterised by the transcription factors NANOG and GATA6, respectively. Here, we present quantitative three-dimensional single cell-based neighbourhood analyses to investigate the spatial distribution of NANOG and GATA6 expression in the ICM of the mouse blastocyst. The cell neighbourhood is characterised by the expression levels of the fate markers in the surrounding cells, together with the number of surrounding cells and cell position. We find that cell neighbourhoods are established in early blastocysts and different for cells expressing different levels of NANOG and GATA6. Highest NANOG expressing cells occupy specific positions within the ICM and are surrounded by 9 neighbours, while GATA6 expressing cells cluster according to their GATA6 levels. The analysis of mutants reveals that NANOG local neighbourhood is regulated by GATA6.Summary statementThree-dimensional cell neighbourhood, which includes fate marker levels, number of neighbouring cells and cell position, determines cell fate decision in early mouse embryos.

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