Biology subjects

Zinski, J.

Publications and source records attributed to Zinski, J..

5 recordsLinked to original sources

bioRxiv2025

Dysregulated lymphocyte localization in idiopathic multicentric Castleman disease

Idiopathic multicentric Castleman disease (iMCD) is a rare and life-threatening hematologic disease involving episodic flares of uncontrollable systemic inflammation by unknown causes. Hallmark features of iMCD include multiple enlarged lymph nodes with characteristic histopathological phenotypes and a potentially fatal, cytokine release syndrome. The key pathophysiologic drivers of disease are poorly understood and few effective treatment options exist. Here, we discovered an association between elevated chemokines, namely CXCL13, and lymph node size in iMCD, providing one possible explanation for the lymphadenopathy observed clinically. Instead of a concurrent increase in circulating CXCL13 and CXCR5-expressing cells that has been described in other contexts, during active disease, chemokine-responsive lymphocytes downregulated CXCR5 levels in iMCD. Despite heightened chemokine production by lymph node stromal cells, T and B cells failed to appropriately respond to their cues locally within the tissue and were particularly scarce within CXCL13-expressing germinal centers (GC). Inflammatory signals in iMCD lymph nodes appeared to restrict the production and movement of T follicular helper cells, which play an important role in facilitating appropriate GC responses. Together, these data provide a link between dysregulated chemokine production and germinal center lymphocyte trafficking, highlighting a potential mechanism and therapeutic target in iMCD lymphadenopathy. One Sentence SummaryLymphocyte chemotaxis to discrete areas of lymphoid tissue is disrupted in idiopathic multicentric Castleman disease.

immunology↗

bioRxiv2025

Oocyte polarity is established independently of the Balbiani body

In most animals, oocyte polarity establishes the embryonic body plan by asymmetrically localizing axis-determining transcripts. These transcripts first localize in Xenopus and zebrafish oocytes to the Balbiani body (Bb), a large membrane-less organelle conserved from insects to humans. The Bb is transient, disassembling and anchoring at one pole the axis-determining transcripts that establish the vegetal pole of the oocyte. Aggregation of the Bb depends on the Bucky ball (Buc) protein, an intrinsically disordered protein with a prion-like self-aggregation domain. In zebrafish buc null mutants, the Bb fails to form and oocytes lack polarity. Here, we established buc hypomorphic mutants that fail to form the Bb, but remarkably Buc protein and vegetal mRNAs localized normally at the vegetal cortex of the oocyte. Thus, these buc hypomorphic mutants displayed normal oocyte polarity, demonstrating that the Bb is not required to establish oocyte polarity. We found that both a reduced Buc protein level and truncation of the N-terminal 10 amino acids contribute to Bb failure in the hypomorphic mutants.

developmental biology↗

bioRxiv2024

A fine kinetic balance of interactions directs transcription factor hubs to genes

Eukaryotic gene regulation relies on the binding of sequence-specific transcription factors (TFs). TFs bind chromatin transiently yet occupy their target sites by forming high-local concentration microenvironments (hubs and condensates) that increase the frequency of binding. Despite their ubiquity, such microenvironments are difficult to study in endogenous contexts due to technical limitations. Here, we use live embryo light-sheet imaging, single-molecule tracking, and genomics to overcome these limitations and investigate how hubs are localized to target genes to drive TF occupancy and transcription. By examining mutants of a hub-forming TF, Zelda, in Drosophila embryos, we find that hub formation propensity, spatial distributions, and temporal stabilities are differentially regulated by DNA binding and disordered protein domains. We show that hub localization to genomic targets is driven by a finely-tuned kinetic balance of interactions between proteins and chromatin, and hubs can be redirected to new genomic sites when this balance is perturbed.

molecular biology↗

bioRxiv2024

EpicTope: narrating protein sequence features to identify non-disruptive epitope tagging sites

Epitope tagging is a valuable technique enabling the in vivo identification, tracking, and purification of proteins. We developed a tool, EpicTope, to facilitate this method by identifying amino acid positions most suitable for epitope insertion. Our method uses a scoring function that considers protein sequence secondary and tertiary structural features, solvent accessibility, and disordered binding regions to determine locations least disruptive to the proteins function. We validated our approach on the zebrafish Smad5 and Hdac1 proteins. We show that multiple predicted internally tagged Smad5 proteins rescue zebrafish smad5 mutant embryos, while the N- and C-terminal tagged variants do not, as predicted. Similarly, we found that optimally-predicted internal and C-terminal Hdac1 tags rescued hdac1 mutant embryos, while a less-optimal N-terminal tag did not. We further show that these functionally tagged Smad5 and Hdac1 proteins are accessible to antibodies in wholemount zebrafish embryo immunohistochemistry, by western blot, and by immunoprecipitation from embryo extracts. Our work demonstrates that EpicTope is an accessible and effective tool for designing epitope tag insertion sites.

developmental biology↗

bioRxiv2021

Bmper is required for morphogenesis of the anterior and posterior semicircular canal ducts in the developing zebrafish inner ear

BMP signalling is known to have a conserved function in development of the semicircular canal system of the vertebrate inner ear, but its regulation, target genes and effects on cell behaviour during otic morphogenesis are not fully understood. We have characterised the effects of mutations in the zebrafish gene bmper, which codes for a regulator of BMP signalling with both pro- and anti-BMP roles in different developmental contexts. The inner ears of bmper mutant embryos develop with truncations of the anterior and posterior semicircular canal ducts. To image the developing ear in live embryos, we have exploited a new transgenic line, Tg(smad6b:EGFP), which exhibits strong GFP expression in the otic epithelium. Morphometric analysis indicates defects in the bmper mutant ear from early stages of semicircular canal formation, correlating with a specific reduction in BMP signalling activity and specific loss of dlx5a expression in dorsal otic epithelium. Subsequent changes to cell shape occur at the truncation site and the dorsolateral septum. The bmper mutations that we describe are adult viable; truncation of the anterior and posterior semicircular canal ducts persists into adulthood. Our results argue against a major role for Bmper in specification of the pre-placodal region, induction of the otic placode, or development of the neural crest, processes in which Bmper function has previously been implicated. Instead, we conclude that a key requirement for Bmper function in the zebrafish is to promote BMP signalling during patterning and morphogenesis of the semicircular canal system.

developmental biology↗