Biology subjects

Ryu, J.-R.

Publications and source records attributed to Ryu, J.-R..

4 recordsLinked to original sources

bioRxiv2026

Characterization of variants associated with Cerebral Small Vessel Disease identifies a functional SNV in Versican

BackgroundSingle nucleotide variants in the non-coding genome can significantly alter disease risk, but identifying the function of SNVs is a challenge. Increasing numbers of variants of unknown significance have been associated with the risk of Stroke, Cerebral Small Vessel Disease and burden of White Matter Hyperintensities, but without biological validation, the significance of these findings is uncertain. MethodsWe use a Multiplexed Parallel Reporter Assay (MPRA) to assay the function of 44 SNVs associated with Cerebral Small Vessel Disease and stroke in EFEMP1, FOXF2, HAAO, KCNK3, NMT1, OPA1, RASL12, STAT3 and VCAN. A functional SNV in versican was further probed using transcriptional reporter and Chromatin Immunoprecipitation assays. ResultsWe identify 26 allele-specific enhancers in where the SNV either increases or decreases transcriptional activity. We validate rs13176921 as an SNV that significantly modulates an intronic enhancer in the matrisome protein Versican and show it affects mRNA levels of the gene. We identify that the transcription factor NKX3.1 binds to the region of this SNV. ConclusionsThus, using MRPA we were able to gain mechanistic insight into which GWAS-identified SNVs modulate transcriptional activity, and validate a functionally important SNV in Versican and provide a mechanism by which it controls its transcription.

genetics↗

bioRxiv2021

midline represses Dpp signaling and target gene expression in Drosophila ventral leg development.

Ventral leg patterning in Drosophila is controlled by the expression of the redundant T-box Transcription factors midline (mid) and H15. Here we show that mid represses the Dpp-activated gene Daughters against decapentaplegic (Dad) through a consensus TBE site in the minimal enhancer, Dad13. Mutating the Dad13 DNA sequence results in an increased and broadening of Dad expression. We further demonstrate that the engrailed-homology-1 domain of Mid is critical for regulating the levels of phospho-Mad, a transducer of Dpp-signaling. However, we find that mid does not affect all Dpp-target genes as we demonstrate that brinker (brk) expression is unresponsive to mid. This study further illuminates the interplay between mechanisms involved in determination of cellular fate and the varied roles of mid. Summary statementVentral patterning is controlled in part by the T-box Transcription factor midline blocking Dpp signaling and Dpp-activated genes, though midline does not affect the Dpp-repressed gene brk.

developmental biology↗

bioRxiv2021

Venous activation of MEK/ERK drives development of arteriovenous malformation and blood 2 flow anomalies with loss of Rasa1

Vascular malformations develop when growth pathway signaling goes awry in the endothelial cells lining blood vessels. Arteriovenous malformations (AVMs) arise where arteries and veins abnormally connect in patients with loss of RASA1, a Ras GTPase activating protein, and, as we show here, in zebrafish rasa1 mutants. Mutant fish develop massively enlarged vessels at the connection between artery and vein in the tail vascular plexus. These AVMs progressively enlarge and become filled with slow-flowing blood and have a greater drop in pulsatility from the artery to the vein. Expression of the flow responsive transcription factor klf2a is diminished in rasa1 mutants, suggesting changes in flow velocity and pattern contribute to the progression of vessel malformations. Migration of endothelial cells is not affected in rasa1 mutants, nor is cell death or proliferation. Early developmental artery-vein patterning is also normal in rasa1 mutants, but we find that MEK/ERK signaling is ectopically activated in the vein as compared to high arterial activation seen in wildtype animals. MEK/ERK signaling inhibition prevents AVM development of rasa1 mutants, demonstrating venous MEK/ERK drives the initiation of rasa1 AVMs. Thus, rasa1 mutants show overactivation of MEK/ERK signaling causes AVM formation, altered blood flow and downstream flow responsive signaling. SummaryThe zebrafish model of RASA1 capillary malformation and arteriovenous malformation (CM-AVM1) develops cavernous vascular malformations driven by ectopic MEK/ERK signaling in the vein, disrupting flow and downstream mechanosensitive signaling.

developmental biology↗

bioRxiv2018

Morphogenesis and differentiation of embryonic vascular smooth muscle cells in zebrafish

Despite the critical role of vascular mural cells (smooth muscle cells and pericytes) in supporting the endothelium of blood vessels, we know little of their early morphogenesis and differentiation. foxc1b:EGFP expressing cells in zebrafish associate with the vascular endothelium (kdrl) and co-express a smooth muscle marker (acta2), but not a pericyte marker (pdgfr{beta}). The expression of foxc1b in early peri-endothelial mesenchymal cells allows us to follow the morphogenesis of mesenchyme into acta2 expressing vascular smooth muscle cells. We show that mural cells expressing different markers associate with vessels of different diameters, depending on their embryonic location and developmental timing, suggesting marker expression is predictive of functional differences. We identify gene expression signatures for an enriched vascular smooth muscle cell population (foxc1b + acta2) and all smooth muscle (acta2) using fluorescence-activated cell sorting and RNA-Seq. Finally, we demonstrate that progressive loss of foxc1a/foxc1b results in decreased smooth muscle cell coverage. Together, our data highlight the early cellular dynamics and transcriptome profiles of smooth muscle cells in vivo, using foxc1b as a unique tool to probe vascular smooth muscle cell differentiation.\n\nSummary StatementTracing the morphogenesis and transcriptome of early vascular smooth muscle cells using foxc1b

developmental biology↗