Biology subjects

Labudina, A.

Publications and source records attributed to Labudina, A..

3 recordsLinked to original sources

bioRxiv2023

Cohesin composition and dosage independently affect early development in zebrafish

Cohesin, a chromatin-associated protein complex with four core subunits (Smc1a, Smc3, Rad21 and either Stag1 or 2), has a central role in cell proliferation and gene expression in metazoans. Human developmental disorders termed "cohesinopathies" are characterised by germline mutations in cohesin or its regulators that do not entirely eliminate cohesin function. However, it is not clear if mutations in individual cohesin subunits have independent developmental consequences. Here we show that zebrafish rad21 or stag2b mutants independently influence embryonic tailbud development. Both mutants have altered mesoderm induction, but only homozygous or heterozygous rad21 mutation affects cell cycle gene expression. stag2b mutants have narrower notochords and reduced Wnt signaling in neuromesodermal progenitors as revealed by single cell RNA-sequencing. Stimulation of Wnt signaling rescues transcription and morphology in stag2b, but not rad21 mutants. Our results suggest that mutations altering the quantity versus composition of cohesin have independent developmental consequences, with implications for the understanding and management of cohesinopathies. Summary StatementViable zebrafish mutants show that cohesin complex quantity versus composition lead to different transcriptional and developmental outcomes in the early embryo.

developmental biology↗

bioRxiv2020

Cohesin components Stag1 and Stag2 differentially influence haematopoietic mesoderm development in zebrafish embryos

Cohesin is a multiprotein complex made up of core subunits Smc1, Smc3 and Rad21, and either Stag1 or Stag2. Normal haematopoietic development relies on crucial functions of cohesin in cell division and regulation of gene expression via three-dimensional chromatin organisation. Cohesin subunit STAG2 is frequently mutated in myeloid malignancies, but the individual contributions of Stag variants to haematopoiesis or malignancy are not fully understood. Zebrafish have four Stag paralogues (Stag1a, Stag1b, Stag2a and Stag2b), allowing detailed genetic dissection of the contribution of Stag1-cohesin and Stag2-cohesin to development. Here we characterize for the first time the expression patterns and functions of zebrafish stag genes during embryogenesis. Using loss-of-function CRISPR-Cas9 zebrafish mutants, we show that stag1a and stag2b contribute to primitive embryonic haematopoiesis. Both stag1a and stag2b mutants present with erythropenia by 24 hours post-fertilisation. Homozygous loss of either paralog alters the number of haematopoietic/vascular progenitors in the lateral plate mesoderm. The lateral plate mesoderm zone of scl-positive cells is expanded in stag1a mutants with concomitant loss of kidney progenitors, and the number of spi1-positive cells are increased, consistent with skewing toward primitive myelopoiesis. In contrast, stag2b mutants have reduced haematopoietic/vascular mesoderm and downregulation of primitive erythropoiesis. Our results suggest that Stag1 and Stag2 proteins cooperate to balance the production of primitive haematopoietic/vascular progenitors from mesoderm.

developmental biology↗

bioRxiv2019

STOCHASTIC SINGLE CELL BEHAVIOUR LEADS TO ROBUST HORIZONTAL CELL LAYER FORMATION IN THE VERTEBRATE RETINA

Developmental programs that arrange cells and tissues into patterned organs are remarkably robust. In the developing vertebrate retina for example, neurons reproducibly assemble into distinct layers giving the mature organ its overall structured appearance. This stereotypic neuronal arrangement, termed lamination, is important for efficient neuronal connectivity. While retinal lamination is conserved in many vertebrates including humans, how it emerges from single cell behaviour is not fully understood. To shed light on this question, we here investigated the formation of the retinal horizontal cell layer. Using in vivo light sheet imaging of the developing zebrafish retina, we generated a comprehensive quantitative analysis of horizontal single cell behaviour from birth to final positioning. Interestingly, we find that all parameters analyzed including cell cycle dynamics, migration paths and kinetics as well as sister cell dispersal are very heterogeneous. Thus, horizontal cells show individual non-stereotypic behaviour before final positioning. Yet, these initially stochastic cell dynamics always generate the correct laminar pattern. Consequently, our data shows that lamination of the vertebrate retina contains a yet underexplored extent of single cell stochasticity.

developmental biology↗