Biology subjects

Gunawan, F.

Publications and source records attributed to Gunawan, F..

8 recordsLinked to original sources

bioRxiv2026

Dll4 and Jag1a signalling act sequentially and cooperatively to drive hematopoietic stem cell fate specification

Hematopoietic stem and progenitor cells (HSPCs) arise from a specialized subset of arterial endothelial cells, the hemogenic endothelium (HE), during embryonic development and sustain blood production throughout life. Notch signalling is a key regulator of this process: its ligand Jag1 promotes HSPC formation, whereas Dll4 promotes arterial identity. However, how the activities of these ligands are temporally coordinated during HSPC emergence remains unresolved. Here we demonstrate that Dll4 is required prior to circulation onset, acting by dampening MAPK signalling to drive the transition from pre-HE to HE fate and enabling HE differentiation towards HSPCs. Subsequently, after circulation starts, Jag1a acts to maintain gene expression in HE and support transition to HSPC fate. Jag1a activity depends on blood flow-induced shear stress and rescues HSPC loss caused by impaired flow. Thus, rather than playing opposing roles, Dll4 and Jag1a act sequentially and coordinately to drive the endothelial-to-hematopoietic transition and promote HSPC emergence.

developmental biology↗

bioRxiv2024

Mechanical Strain Activates Planar Cell Polarity Signaling to Coordinate Vascular Cell Dynamics

Mechanical stimuli, particularly laminar blood flow, play a crucial role in shaping the vascular system. Changes in the rate of blood flow manifest in altered shear stress, which activates signaling cascades that drive vascular remodeling. Consistently, dysregulation of the endothelial response to fluid shear forces and aberrant flow patterns both lead to pathological conditions, including impaired blood vessel development and atherosclerosis. Despite its importance, the mechanisms driving the coordinated cell behavior underlying vascular remodeling are not fully understood. Combining classical cell biological approaches with advanced image analysis, mathematical modeling, biomimetic strategies, and in vivo studies, we identify the planar cell polarity (PCP) protein Vangl1 as an enforcer of flow-dependent cell dynamics in the vascular system. We demonstrate that shear stress triggers the relocation of Vangl1 from an internal reservoir to the plasma membrane at the initiation of cell remodeling. Membrane enrichment of Vangl1 is mediated by a Coronin1C-dependent shift in the equilibrium between endo- and exocytosis and results in the spatial reorganization of another essential PCP protein, Frizzled6 (Fzd6). The resulting mutual exclusion of the core PCP proteins Fzd6 and Vangl1 augments differential junctional and cytoskeletal dynamics along the flow axis. Loss of Vangl1 limits the ability of endothelial cells to respond to shear forces in a coordinated fashion, resulting in irregular cell alignment along the flow direction and erroneous vessel sprouting. Together, these studies introduce core PCP signaling as a determinant of collective cell dynamics and organization of the vascular system.

cell biology↗

bioRxiv2022

Adgrg6/Gpr126 is required for myocardial Notch activity and N-cadherin localization to attain trabecular identity

How adhesion G protein-coupled receptors (aGPCRs) control development remains unclear. The aGPCR Adgrg6/Gpr126 has been associated with heart trabeculation. Defects in this process cause cardiomyopathies and embryonic lethality. Yet, how cardiomyocytes attain trabecular identity is poorly understood. Here, we show that Gpr126 regulates Notch activity and N-cadherin localization that are necessary for attaining trabecular identity in zebrafish. Maternal zygotic gpr126stl47 early truncation mutants exhibit hypotrabeculation whereby N-cadherin distributes randomly at apical/basal membranes of compact layer cardiomyocytes. In contrast, gpr126st49 mutants expressing a N-terminal fragment lacking the GPS motif (NTF{Delta}GPS) exhibit a multilayered ventricular wall consisting of polarized cardiomyocytes with normal N-cadherin expression and increased Notch signaling. Notably, endocardially expressed C-terminal fragment (CTF) reinstates trabeculation in gpr126st49 mutants. Collectively, our data indicate domain-specific roles of Gpr126 during trabeculation whereby the NTF maintains cell-cell adhesion and is required for compact wall integrity, while the CTF is essential to provide trabecular identity

developmental biology↗

bioRxiv2021

The developing epicardium regulates cardiac chamber morphogenesis by promoting cardiomyocyte growth

The epicardium, the outermost layer of the heart, is an important regulator of cardiac regeneration. However, a detailed understanding of the crosstalk between the epicardium and myocardium during development requires further investigation. Here, we generated three models of epicardial impairment in zebrafish by mutating the transcription factor genes tcf21 and wt1a, and by ablating tcf21+ epicardial cells. Notably, all three epicardial-impairment models exhibit smaller ventricles. We identified the initial cause of this phenotype as defective cardiomyocyte growth, resulting in reduced cell surface and volume. This failure of cardiomyocytes to grow is followed by decreased proliferation and increased abluminal extrusion. By temporally manipulating its ablation, we show that the epicardium is required to support ventricular growth during early cardiac morphogenesis. By transcriptomic profiling of sorted epicardial cells, we identified reduced expression of FGF and VEGF ligand genes in tcf21-/- hearts, and pharmacological inhibition of these signaling pathways partially recapitulated the ventricular growth defects. Thus, the analysis of these epicardial-impairment models further elucidates the distinct roles of the epicardium during cardiac morphogenesis and the signaling pathways underlying epicardial-myocardial crosstalk.

developmental biology↗

bioRxiv2021

Defining the Yeast Resistome through in vitro Evolution and Whole Genome Sequencing

In vitro evolution and whole genome analysis were used to comprehensively identify the genetic determinants of chemical resistance in the model microbe, Saccharomyces cerevisiae. Analysis of 355 curated, laboratory-evolved clones, resistant to 80 different compounds, demonstrates differences in the types of mutations that are identified in selected versus neutral evolution and reveals numerous new, compound-target interactions. Through enrichment analysis we further identify a set of 137 genes strongly associated with or conferring drug resistance as indicated by CRISPR-Cas9 engineering. The set of 25 most frequently mutated genes was enriched for transcription factors and for almost 25 percent of the compounds, resistance was mediated by one of 100 independently derived, gain-of-function, single nucleotide variants found in 170-amino-acid domains in two Zn2C6 transcription factors, YRR1 and YRM1 (p < 1x 10 -100). This remarkable enrichment for transcription factors as drug resistance genes may explain why it is challenging to develop effective antifungal killing agents and highlights their important role in evolution.

genetics↗

bioRxiv2020

The EMT transcription factor Snai1 maintains myocardial wall integrity by repressing intermediate filament gene expression

The zinc finger transcription factor Snai1 is a well-known regulator of epithelial-to-mesenchymal transition (EMT)1, 2; it is required for mesoderm ingression in flies3 and neural crest delamination in vertebrates4. During cardiac development, Snai1-regulated EMT is necessary for myocardial precursor migration and valve formation5, 6. However, a role for Snai1 in maturing cardiomyocytes (CMs) has not been reported. Here, using genetic, transcriptomic and chimeric analyses in zebrafish, we find that Snai1b is required for myocardial wall integrity. Global loss of snai1b leads to the extrusion of CMs away from the cardiac lumen, a process we show is dependent on cardiac contractility. Examining CM junctions in snai1b mutants, we observed that N-cadherin localization was compromised, thereby likely weakening cell-cell adhesion. In addition, extruding CMs exhibit increased actomyosin contractility basally, as revealed by the specific enrichment of canonical markers of actomyosin tension - phosphorylated myosin light chain (active myosin) and the -catenin epitope -18. By comparing the transcriptome of wild-type and snai1b mutant hearts at early stages of CM extrusion, we found the dysregulation of intermediate filament genes in mutants including the upregulation of desmin b. We tested the role of desmin b in myocardial wall integrity and found that CM-specific desmin b overexpression led to CM extrusion, recapitulating the snai1b mutant phenotype. Altogether, these results indicate that Snai1 is a critical regulator of intermediate filament gene expression in CMs, and that it maintains the integrity of the myocardial epithelium during embryogenesis, at least in part by repressing desmin b expression.

developmental biology↗

bioRxiv2018

Myh10 deficiency leads to defective extracellular matrix remodeling and pulmonary disease

Impaired alveolar formation and maintenance are features of many pulmonary diseases that are associated with significant morbidity and mortality. In a forward genetic screen for modulators of mouse lung development, we identified the non-muscle myosin II heavy chain gene, Myh10. Myh10 mutant pups exhibit cyanosis and respiratory distress, and die shortly after birth from differentiation defects in alveolar epithelium and mesenchyme. From omics analyses and follow up studies, we find decreased Thrombospondin expression accompanied with increased matrix metalloproteinase activity in both mutant lungs and cultured mutant fibroblasts, as well as disrupted extracellular matrix (ECM) remodeling. Loss of Myh10 specifically in mesenchymal cells results in ECM deposition defects and alveolar simplification. Notably, MYH10 expression is down-regulated in the lung of emphysema patients. Altogether, our findings reveal critical roles for Myh10 in alveologenesis at least in part via the regulation of ECM remodeling, which may contribute to the pathogenesis of emphysema.

developmental biology↗

bioRxiv2018

The potassium channel KCNJ13 is essential for smooth muscle cytoskeletal organization during mouse tracheal tubulogenesis

Tubulogenesis is essential for the formation and function of internal organs. One such organ is the trachea, which allows gas exchange between the external environment and the lungs. However, the cellular and molecular mechanisms underlying tracheal tube development remain poorly understood. Here, we show that the potassium channel KCNJ13 is a critical modulator of tracheal tubulogenesis. We identify Kcnj13 in an ethylnitrosourea forward genetic screen for regulators of mouse respiratory organ development. Kcnj13 mutants exhibit a shorter trachea as well as defective smooth muscle (SM) cell alignment and polarity. KCNJ13 is essential to maintain ion homeostasis in tracheal SM cells, which is required for actin polymerization. This process appears to be mediated, at least in part, through activation of the actin regulator AKT, as pharmacological increase of AKT phosphorylation ameliorates the Kcnj13 mutant trachea phenotypes. These results provide insights into the role of ion homeostasis in cytoskeletal organization during tubulogenesis.

developmental biology↗