Biology subjects

Uosaki, H.

Publications and source records attributed to Uosaki, H..

5 recordsLinked to original sources

bioRxiv2021

Noncanonical Notch signals have opposing roles during cardiac development

The Notch pathway is an ancient intercellular signaling system with crucial roles in numerous cell-fate decision processes across species. While the canonical pathway is activated by ligand-induced cleavage and nuclear localization of membrane-bound Notch, Notch can also exert its activity in a ligand/transcription-independent fashion, which is conserved in Drosophila, Xenopus, and mammals. However, the noncanonical role remains poorly understood in in vivo processes. Here we show that increased levels of the Notch intracellular domain (NICD) in the early mesoderm inhibit heart development, potentially through impaired induction of the second heart field (SHF), independently of the transcriptional effector RBP-J. Similarly, inhibiting Notch cleavage, shown to increase noncanonical Notch activity, suppressed SHF induction in embryonic stem cell (ESC)-derived mesodermal cells. In contrast, NICD overexpression in late cardiac progenitor cells lacking RBP-J resulted in an increase in heart size. Our study suggests that noncanonical Notch signaling has stagespecific roles during cardiac development.

developmental biology↗

bioRxiv2021

Cross-organ transcriptomic comparison reveals universal factors during maturation

Various cell types can be derived from stem cells. However, these cells are immature and do not match their adult counterparts in functional capabilities, limiting their use in disease modeling and cell therapies. Thus, it is crucial to understand the mechanisms of maturation in vivo. However, it is unknown if there are genes and pathways conserved across organs during maturation. To address this, we performed a time-series analysis of the transcriptome of the mouse heart, brain, liver, and kidney and analyzed their trajectories over time. In addition, gene regulatory networks were reconstructed to determine overlapping expression patterns. Based on these, we identified commonly upregulated and downregulated pathways across all four organs. Key upstream regulators were also predicted based on the temporal expression of downstream genes. These findings suggest the presence of universal regulators during organ maturation, which may help us develop a general strategy to mature stem cell-derived cells in vitro.

bioinformatics↗

bioRxiv2021

Cardiac progenitors auto-regulate second heart field cell fate via Wnt secretion

Proper heart formation requires coordinated development of two anatomically distinct groups of cells - the first and second heart fields (FHF and SHF). Given that congenital heart defects are often restricted to derivatives of the FHF or SHF, it is crucial to understand the mechanisms controlling their development. Wnt signaling has previously been implicated in SHF proliferation; however, the source of Wnts remains unknown. Through comparative gene analysis, we found upregulation of Wnts and Wnt receptor/target genes in the FHF and SHF, respectively, raising the possibility that early cardiac progenitors may secrete Wnts to influence SHF cell fate. To probe this further, we deleted Wntless (Wls), a gene required for Wnt ligand secretion, in various populations of precardiac cells. Deletion of Wls in Mesp1+ cells resulted in formation of a single chamber heart with left ventricle identity, implying compromised SHF development. This phenotype was recapitulated by deleting Wls in cells expressing Islet1, a pan-cardiac marker. Similarly, Wls deletion in cells expressing Nkx2.5, a later-expressed pan-cardiac marker, resulted in hypoplastic right ventricle, a structure derived from the SHF. However, no developmental defects were observed when deleting Wls in SHF progenitors. To gain mechanistic insights, we isolated Mesp1-lineage cells from developing embryos and performed single-cell RNA-sequencing. Our comprehensive single cell transcriptome analysis revealed that Wls deletion dysregulates developmental trajectories of both anterior and posterior SHF cells, marked by impaired proliferation and premature differentiation. Together, these results demonstrate a critical role of local precardiac mesodermal Wnts in SHF fate decision, providing fundamental insights into understanding heart field development and chamber formation. Significance StatementThere is significant interest in understanding the mechanisms underlying heart formation to develop treatments and cures for patients suffering from congenital heart disease. In particular, we were interested in the intricacies of first (FHF) and second heart field (SHF) development, as many congenital heart defects present with heart field-specific etiologies. Here, we uncovered a novel relationship between specified cardiac progenitor cells and second heart field progenitors. Through genetic manipulation of Wnt secretion in developing mouse embryos, we identified a population of cardiac progenitor cells that acts as a local source of Wnts which are necessary for proper SHF development. Our single cell transcriptomic analysis of developing anterior mesoderm showed cardiac progenitor-secreted Wnts function through regulation of differentiation and proliferation among SHF progenitors. Thus, this study provides insight into the source and timing of Wnts required for SHF development, and points to the crucial role of co-developing cell populations in heart development.

developmental biology↗

bioRxiv2020

Disentangling the biological information encoded in disordered mitochondrial morphology through its rapid elicitation by iCMM

Mitochondrial morphology is dynamically changed in conjunction with spatiotemporal functionality. Although considerable efforts have been made to understand why abnormal mitochondrial morphology occurs in various diseases, the biological significance of mitochondrial morphology in states of health and disease remains to be elucidated owing to technical limitations. In the present study, we developed a novel method, termed inducible Counter Mitochondrial Morphology (iCMM), to purposely manipulate mitochondrial morphological patterns on a minutes timescale, using a chemically inducible dimerization system. Using iCMM, we showed that mitochondrial morphological changes rapidly lead to the characteristic reconstitution of various biological information, which is difficult to investigate by conventional genetic engineering. The manipulation of mitochondrial morphology using iCMM can improve our understanding of the interplay between mitochondrial morphology and cellular functions.Competing Interest StatementThe authors have declared no competing interest.View Full Text

synthetic biology↗

bioRxiv2020

PGC1/PPAR Drive Cardiomyocyte Maturation through Regulation of Yap1 and SF3B2

Cardiomyocytes undergo significant levels of structural and functional changes after birth--fundamental processes essential for the heart to produce the volume and contractility to pump blood to the growing body. However, due to the challenges in isolating single postnatal/adult myocytes, how individual newborn cardiomyocytes acquire multiple aspects of mature phenotypes remains poorly understood. Here we implemented large-particle sorting and analyzed single myocytes from neonatal to adult hearts. Early myocytes exhibited a wide-ranging transcriptomic and size heterogeneity, maintained until adulthood with a continuous transcriptomic shift. Gene regulatory network analysis followed by mosaic gene deletion revealed that peroxisome proliferator-activated receptor coactivator-1 signaling--activated in vivo but inactive in pluripotent stem cell-derived cardiomyocytes--mediates the shift. The signaling regulated key aspects of cardiomyocyte maturation simultaneously through previously unrecognized regulators, including Yap1 and SF3B2. Our study provides a single-cell roadmap of heterogeneous transitions coupled to cellular features and unveils a multifaceted regulator controlling cardiomyocyte maturation. Significance StatementHow the individual single myocytes achieve full maturity remains a black box, largely due to the challenges with the isolation of single mature myocytes. Understanding this process is particularly important as the immaturity and early developmental arrest of pluripotent stem cell-derived myocytes has emerged a major concern in the field. Here we present the first study of high-quality single-cell transcriptomic analysis of cardiac muscle cells from neonatal to adult hearts. We identify a central transcription factor and its novel targets that control key aspects of myocyte maturation, including cellular hypertrophy, contractility, and mitochondrial activity.

developmental biology↗