Biology subjects

Muncie, J. M.

Publications and source records attributed to Muncie, J. M..

4 recordsLinked to original sources

bioRxiv2022

A spatiotemporal gradient of mesoderm assembly governs cell fate and morphogenesis of the early mammalian heart

Using four-dimensional whole-embryo light sheet imaging with improved and accessible computational tools, we longitudinally reconstruct early murine cardiac development at single-cell resolution. Nascent mesoderm progenitors form opposing density and motility gradients, converting the temporal birth sequence of gastrulation into a spatial anterolateral-to-posteromedial arrangement. Migrating precardiac mesoderm doesnt strictly preserve cellular neighbor relationships; spatial patterns only become solidified as the cardiac crescent emerges. Progenitors undergo a heretofore unknown mesenchymal-to-epithelial transition, with a first heart field (FHF) ridge apposing a motile juxtacardiac field (JCF). Anchored along the ridge, the FHF epithelium rotates the JCF forward due to push-pull morphodynamics of the second heart field, which forms the nascent heart tube. In Mesp1 mutants that fail to make a cardiac crescent, mesoderm remains highly motile but directionally incoherent, resulting in density gradient inversion. Our practicable live embryo imaging approach defines spatial origins and behaviors of cardiac progenitors, and identifies their unanticipated morphological transitions.

developmental biology↗

bioRxiv2020

Cytoskeletal tension forces mitohormesis

Mitochondria control eukaryotic cell fate by producing the energy needed to support life and the signals required to execute programmed cell death. The biochemical milieu is known to affect mitochondrial function and contribute to the dysfunctional mitochondrial phenotypes implicated in cancer and the morbidities of ageing. However, the physical characteristics of the extracellular matrix are also altered in cancer and in aging tissues. We demonstrate that cells sense the physical properties of the extracellular matrix and activate a mitochondrial stress response that adaptively tunes mitochondrial function via SLC9A1-dependent ion exchange and HSF1-dependent transcription. Overall, our data indicate that adhesion-mediated mechanosignaling may play an unappreciated role in the altered mitochondrial functions observed in aging and cancer. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=154 SRC="FIGDIR/small/979583v3_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@1ecdaceorg.highwire.dtl.DTLVardef@1112c32org.highwire.dtl.DTLVardef@6c99a1org.highwire.dtl.DTLVardef@1da1e5f_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2020

Mechanics regulate human embryonic stem cell self-organization to specify mesoderm

Embryogenesis is directed by morphogens that induce differentiation within a defined tissue geometry. Tissue organization is mediated by cell-cell and cell-extracellular matrix (ECM) adhesions and is modulated by cell tension and tissue-level force. Whether cell tension regulates development by directly influencing morphogen signaling remains unclear. Human embryonic stem cells (hESCs) exhibit an intrinsic capacity for self-organization that motivates their use as a tractable model of early human embryogenesis. We engineered patterned substrates that enhance cell-cell interactions to direct the self-organization of cultured hESCs into "gastrulation-like" nodes. Tissue geometries that generate local nodes of high cell-cell tension and induce these self-organized tissue nodes drive BMP4-dependent gastrulation by enhancing phosphorylation and nuclear translocation of {beta}-catenin to promote Wnt signaling and mesoderm specification. The findings underscore the interplay between tissue organization, cell tension, and morphogen-dependent differentiation, and demonstrate that cell- and tissue-level forces directly regulate cell fate specification in early human development. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/943076v1_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@e21aaeorg.highwire.dtl.DTLVardef@45c41forg.highwire.dtl.DTLVardef@4ee902org.highwire.dtl.DTLVardef@a3837d_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG HighlightsO_LISubstrates that enhance cell-cell adhesion promote hESC self-organization C_LIO_LITissue nodes exhibiting high tension are predisposed to gastrulation induction C_LIO_LIColony geometry dictates the localization of tension nodes to specify mesoderm C_LIO_LITension activates {beta}-catenin and stimulates Wnt signaling to induce mesoderm C_LI In BriefEngineered substrates that promote cell-cell adhesion and reconstitute epiblast tissue organization facilitate "gastrulation-like" morphogenesis in cultured hESCs. Tissue geometries that foster localized regions of high cell-cell tension potentiate BMP4-dependent mesoderm specification by enhancing phosphorylation and nuclear translocation of {beta}-catenin to promote Wnt signaling.

developmental biology↗

bioRxiv2018

Spatiotemporal mosaic patterning of pluripotent stem cells using CRISPR interference

Morphogenesis results from the interactions of asymmetric cell populations to form complex multicellular patterns and structures comprised of distinct cell types. However, current methods to model morphogenic events offer little control over parallel cell type co-emergence and do not offer the capability to selectively perturb gene expression in specific subpopulations of cells. We have developed an in vitro system that can spatiotemporally interrogate cell-cell interactions and multicellular organization within human induced pluripotent stem cell (hiPSC) colonies. We examined the effects of independently knocking down molecular regulators of cortical tension and cell-cell adhesion using inducible CRISPRi: Rho-associated kinase-1 (ROCK1) and E-cadherin (CDH1), respectively. Induced mosaic knockdown of ROCK1 or CDH1 in hiPSC populations resulted in differential patterning events within hiPSC colonies indicative of cell-driven population organization. Patterned colonies retained an epithelial phenotype and nuclear expression of pluripotency markers. Gene expression within each of the mixed populations displayed a transient wave of differential expression with induction of knockdown that stabilized in coordination with intrinsic pattern formation. Mosaic patterning of hiPSCs enables the genetic interrogation of emergent multicellular properties of pluripotent cells, leading to a greater mechanistic understanding of the specific molecular pathways regulating the dynamics of symmetry breaking events that transpire during developmental morphogenesis.\n\nSIGNIFICANCEHuman embryonic development entails a series of multicellular morphogenic events that lead to primitive tissue formation. Attempts to study human morphogenic processes experimentally have been limited due to divergence from model organisms and the inability of current human in vitro models to accurately control the coincident emergence of heterogeneous cell populations in the spatially controlled manner necessary for proper tissue structure. We developed a human induced pluripotent stem cell (iPSC) in vitro model that enables temporal control over the emergence of heterotypic subpopulations of cells. We examined mosaic knockdown of two target molecules to create predictable and robust cell-patterning events within hiPSC colonies. This method allows for dynamic interrogation of intrinsic cell mechanisms that initiate symmetry breaking events and provides direct insight(s) into tissue developmental principles.

bioengineering↗