Biology subjects

Tarbashevich, K.

Publications and source records attributed to Tarbashevich, K..

5 recordsLinked to original sources

bioRxiv2026

Germ granules act as repositories for RNA and protein molecules essential for zebrafish germline development

Germ granules are conserved, phase-separated ribonucleoprotein condensates enriched in germline determinants, yet their precise function remains unclear. Using quantitative live imaging, translational reporters, and targeted disruption of germ granule assembly in zebrafish primordial germ cells, we show that germ granules are dispensable for germ cell fate, migration, and gamete production. Instead, granules act as reservoirs, sequestering transcripts and releasing them gradually for cytoplasmic translation. Under heat stress or translational inhibition, granules further accumulate mRNAs and canonical stress granule factors, indicating a role in buffering RNA and regulatory protein availability rather than serving as sites of localized translation, as previously proposed. Consistent with this reservoir model, cytoplasmic expression of the germline determinants Nanos3 and Dead end is sufficient to direct somatic cells toward a germline fate even in the absence of germ granules. Correspondingly, germ cells lacking granules develop normally but show reduced persistence of germline RNA expression and impaired fertility. Together, these findings establish zebrafish germ granules as protective condensates that safeguard germline determinants and enhance developmental robustness by buffering the timing and rate of RNA translation.

cell biology↗

bioRxiv2025

Optochemical control over mRNA translation by photocaged phosphorodiamidate morpholino oligonucleotides in vivo

A key regulatory step in protein synthesis is the initiation of mRNA translation. We developed an efficient, robust, and broadly applicable system for light-induced protein translation to control the production of proteins of interest and study their function. The method is based on the displacement of a single type of antisense morpholino from RNA by the uncaged guanidinium-linked morpholino (GMO)-phosphorodiamidate morpholino oligonucleotide (PMO) chimera upon UV irradiation. The GMO-PMO chimera designed here is cell-permeable and the GMO part can be produced employing a new mercury-free approach compatible with the synthesis on solid support. We demonstrate the function of this novel optochemical approach in live embryos by inducing, at desired times and locations, the expression of proteins that label specific cells, ablate tissue regions, and affect embryonic development. Together, our results demonstrate that the cell-permeable GMO-PMO chimera offers a unique strategy for controlling the function of mRNAs of interest. This method allows for the production of proteins at specific times and positions within live organisms, facilitating numerous applications in biomedical research and therapy.

developmental biology↗

bioRxiv2023

Spatial organization and function of RNA molecules within phase-separatedcondensates are controlled by Dnd1

Germ granules, condensates of phase-separated RNA and protein, are organelles essential for germline development in different organisms The patterning of the granules and its relevance for germ cell fate are not fully understood. Combining three-dimensional in vivo structural and functional analyses, we study the dynamic spatial organization of molecules within zebrafish germ granules. We find that localization of RNA molecules to the periphery of the granules, where ribosomes are localized depends on translational activity at this location. In addition, we find that the vertebrate-specific Dead end (Dnd1) protein is essential for nanos3 RNA localization at the condensates periphery. Accordingly, in the absence of Dnd1, or when translation is inhibited, nanos3 RNA translocates into the granule interior, away from the ribosomes, a process that is correlated with loss of germ cell fate. These findings highlight the relevance of sub-granule compartmentalization for posttranscriptional control, and its importance for preserving germ cell totipotency.

cell biology↗

bioRxiv2022

Primordial germ cells adjust their protrusion type while migrating in different tissue contexts in vivo

In both physiological processes and disease contexts, migrating cells have the ability to adapt to conditions in their environment. As an in vivo model for this process, we use zebrafish primordial germ cells that migrate throughout the developing embryo. When migrating within an ectodermal environment, the germ cells form fewer and smaller blebs as compared with their behavior within mesodermal environment. We find that cortical tension of neighboring cells is a parameter that affects blebbing frequency. Interestingly, the change in blebbing activity is accompanied by the formation of more actin-rich protrusions. These alterations in cell behavior that correlate with changes in RhoA activity could allow the cells to maintain dynamic motility parameters, such as migration speed and track straightness, in different settings. In addition, we find that the polarity of the cells can be affected by stiff structures positioned in their migration path.

cell biology↗

bioRxiv2022

Patterning of phase-separated condensates by Dnd1 controls cell fate

Germ granules, condensates of phase-separated RNA and protein, are essential for germline development, but how these molecules are organized within the granules and whether such an organization is relevant for germ cell fate is unclear. Combining three-dimensional in vivo structural and functional analyses, we study the dynamic spatial organization of molecules within zebrafish germ granules. We find that the vertebrate-specific Dead end protein is essential for positioning nanos3 RNA at the condensates periphery, where ribosomes are located. Without Dead end, or when translation is inhibited, nanos3 RNA translocates into granule interiors, far from the ribosomes location. These findings reveal the molecular mechanisms controlling the spatial organization of RNA within the phase-separated organelle and the importance of subgranule RNA localization for preserving germ cell totipotency.

cell biology↗