Many embryonic organs undergo epithelial morphogenesis to form tree-like hierarchical structures. However, it remains unclear what drives the budding and branching of stratified epithelia, such as in ...the embryonic salivary gland and pancreas. Here, we performed live-organ imaging of mouse embryonic salivary glands at single-cell resolution to reveal that budding morphogenesis is driven by expansion and folding of a distinct epithelial surface cell sheet characterized by strong cell-matrix adhesions and weak cell-cell adhesions. Profiling of single-cell transcriptomes of this epithelium revealed spatial patterns of transcription underlying these cell adhesion differences. We then synthetically reconstituted budding morphogenesis by experimentally suppressing E-cadherin expression and inducing basement membrane formation in 3D spheroid cultures of engineered cells, which required β1-integrin-mediated cell-matrix adhesion for successful budding. Thus, stratified epithelial budding, the key first step of branching morphogenesis, is driven by an overall combination of strong cell-matrix adhesion and weak cell-cell adhesion by peripheral epithelial cells.
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•Single-cell tracking and RNA-seq identify mechanisms driving budding morphogenesis•In stratified epithelia, the surface cell sheet can expand and fold to form buds•A combination of strong cell-matrix and weak cell-cell adhesions is critical•Applying these principles permits synthetic reconstitution of budding morphogenesis
Using live-organ imaging and transcriptomics, epithelial morphogenesis into tree-like hierarchical structures was profiled at single-cell resolution, and the early steps were synthetically reconstituted in 3D spheroid cultures of engineered cells.
Planar cell polarity (PCP) is an essential feature of animal tissues, whereby distinct polarity is established within the plane of a cell sheet. Tissue-wide establishment of PCP is driven by multiple ...global cues, including gradients of gene expression, gradients of secreted WNT ligands and anisotropic tissue strain. These cues guide the dynamic, subcellular enrichment of PCP proteins, which can self-assemble into mutually exclusive complexes at opposite sides of a cell. Endocytosis, endosomal trafficking and degradation dynamics of PCP components further regulate planar tissue patterning. This polarization propagates throughout the whole tissue, providing a polarity axis that governs collective morphogenetic events such as the orientation of subcellular structures and cell rearrangements. Reflecting the necessity of polarized cellular behaviours for proper development and function of diverse organs, defects in PCP have been implicated in human pathologies, most notably in severe birth defects.
Mammalian palatogenesis is a highly regulated morphogenetic process during which the embryonic primary and secondary palatal shelves develop as outgrowths from the medial nasal and maxillary ...prominences, respectively, remodel and fuse to form the intact roof of the oral cavity. The complexity of control of palatogenesis is reflected by the common occurrence of cleft palate in humans. Although the embryology of the palate has long been studied, the past decade has brought substantial new knowledge of the genetic control of secondary palate development. Here, we review major advances in the understanding of the morphogenetic and molecular mechanisms controlling palatal shelf growth, elevation, adhesion and fusion, and palatal bone formation.
The unique architecture of the mammalian lung is required for adaptation to air breathing at birth and thereafter. Understanding the cellular and molecular mechanisms controlling its morphogenesis ...provides the framework for understanding the pathogenesis of acute and chronic lung diseases. Recent single-cell RNA sequencing data and high-resolution imaging identify the remarkable heterogeneity of pulmonary cell types and provides cell selective gene expression underlying lung development. We will address fundamental issues related to the diversity of pulmonary cells, to the formation and function of the mammalian lung, and will review recent advances regarding the cellular and molecular pathways involved in lung organogenesis. What cells form the lung in the early embryo? How are cell proliferation, migration, and differentiation regulated during lung morphogenesis? How do cells interact during lung formation and repair? How do signaling and transcriptional programs determine cell-cell interactions necessary for lung morphogenesis and function?
Gossypium hirsutum is an important source of natural textile fibers. Gossypol, which is a sesquiterpenoid compound mainly existing in the cotton pigment glands, can facilitate resistance to the ...stress from diseases and pests. The level of gossypol in the cotton is positively correlated to the quantity of pigment glands. However, the underlying regulatory mechanisms of gossypol synthesis and gland morphogenesis are still poorly understood, especially from a transcriptional perspective. The transcripts of young leaves and ovules at 30 DPA of the glanded plants and glandless plants were studied by RNA-Seq and 865 million clean reads were obtained. A total of 34,426 differentially expressed genes (DEGs) were identified through comparative transcriptome analysis. Genes related to gossypol synthesis or gland morphogenesis displayed significant differential expression between the two cultivars. Functional annotation revealed that the candidate genes related to catalytic activity, the biosynthesis of secondary metabolites, and biomolecular decomposition processes. Our work herein unveiled several potential candidate genes related to gossypol synthesis or gland morphogenesis and may provide useful clues for a breeding program of cotton cultivars with low cottonseed gossypol contents.
Oriented cell divisions (OCDs) represent a fundamental mechanism for tissue morphogenesis, repair and differentiation where the mitotic spindle is oriented along a specific polarity axis. Early ...research identified the evolutionarily conserved Gαi/LGN/NuMA ternary complex that mediates orientation of the mitotic spindle by being restricted to specific cortical regions. The mechanisms that control the recruitment of these proteins to the cortex remain unfolding, particularly in epithelial systems such as the mammary gland. The mammary gland represents a unique organ that develops predominantly after birth where postnatal morphogenesis of the mammary gland drives dramatic tissue turnover and remodelling. Thus, differentiation and proliferation are constantly balanced to allow normal mammary gland development and homeostasis. How mammary epithelial cells regulate mitotic spindle orientation, hence OCDs, to accompany the rapid and constant tissue turnover is not well understood. This study aimed to identify novel factors that regulate the LGN-mediated spindle orientation machinery and determine how their dysregulation affects OCDs in mammary epithelial cells. By combining co-immunoprecipitation with mass spectrometry, the LGN interactome at the cell cortex of mitotic mammary epithelial cells was characterised and the membrane-associated protein Annexin A1 (ANXA1) was identified as a novel partner of LGN. Confocal and time-lapse microscopy demonstrated a critical role of ANXA1 in regulating the position and planar orientation of the mitotic spindle by instructing the accumulation and restriction of the LGN complex at the lateral cortex. Moreover, loss of ANXA1 leads to mitotic spindle misassembly and chromosome segregation defects, affecting the dynamics and progression of mitosis. Collectively the present study identified ANXA1 as a novel intrinsic cue of OCDs in mammary epithelial cells. Given increasing evidence of a link between OCD and tumorigenesis, this work is not only important for advancing our understanding of normal epithelial biology but also elucidating how imbalance of OCDs can contribute to the abnormal cell behaviour observed in cancer.
Human 2-oxoglutarate (2OG) and iron-dependent oxygenases catalyse an emerging post-translational modification, hydroxylation, on a range of substrates including DNA, RNA and protein. Despite the ...well-recognised roles of 2OG oxygenases in oxygen sensing and epigenetic regulation of transcription, much work remains to be done to elucidate the roles of the less well-characterised family members in physiology and disease. Myc-induced nuclear antigen (MINA) is a 2OG oxygenase that catalyses histidyl hydroxylation of the large ribosomal subunit protein RPL27A. The paradoxical role of MINA in cancer, however, suggests the potential existence of additional substrates or functions. Here, we identify and explore a novel role of MINA in epithelial morphogenesis. We begin by characterising the physiological and pathological cues that contribute to the nucleolar retention and release of MINA. We then identify and characterise a novel activity-dependent and extra-nucleolar interaction between MINA and a membrane-associated guanylate kinase, membrane palmitoylated protein 6 (MPP6). Subsequent studies explored the role of MINA localisation, activity and MPP6 in epithelial morphogenesis. Overall, our findings suggest that extra-nucleolar MINA functions as a tumour suppressor, possibly through its interaction with MPP6. Moreover, the work presented in this thesis suggests a novel mechanism by which the tumour suppressor function of MINA may be broadly inactivated in cancer.
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