Myosin 1b regulates intestinal epithelial morphogenesis via interaction with UNC45A.

Vesicle trafficking and the establishment of apicobasal polarity are essential processes in epithelial morphogenesis. UNC45A deficiency has been reported in a multi-organ syndrome presenting with severe diarrhea associated with enterocyte polarity defects. Myosin 1b, an actin motor able to bind membranes, regulates membrane shaping and vesicle trafficking.

SIN-3 transcriptional coregulator maintains mitochondrial homeostasis and polyamine flux.

Mitochondrial function relies on the coordinated transcription of mitochondrial and nuclear genomes to assemble respiratory chain complexes. Across species, the SIN3 coregulator influences mitochondrial functions, but how its loss impacts mitochondrial homeostasis and metabolism in the context of a whole organism is unknown. Exploring this link is important because haploinsufficiency causes intellectual disability/autism syndromes and SIN3 plays a role in tumor biology.

PAR-4/LKB1 prevents intestinal hyperplasia by restricting endoderm specification in Caenorhabditis elegans embryos.

The kinase PAR-4/LKB1 is a major regulator of intestinal homeostasis, which prevents polyposis in humans. Moreover, its ectopic activation is sufficient to induce polarization and formation of microvilli-like structures in intestinal cell lines. Here, we use Caenorhabditis elegans to examine the role of PAR-4 during intestinal development in vivo.

Crb3 is required to organize the apical domain of multiciliated cells.

Cell shape changes mainly rely on the remodeling of the actin cytoskeleton. Multiciliated cells (MCCs) of the mucociliary epidermis of Xenopus laevis embryos, as they mature, dramatically reshape their apical domain to grow cilia, in coordination with the underlying actin cytoskeleton. Crumbs (Crb) proteins are multifaceted transmembrane apical polarity proteins known to recruit actin linkers and promote apical membrane growth.

Sparse denoising and adaptive estimation enhances the resolution and contrast of fluorescence emission difference microscopy based on an array detector.

An array detector allows a resolution gain for confocal microscopy by combining images sensed by a set of photomultipliers tubes (or sub-detectors). Several methods have been proposed to reconstruct a high-resolution image by linearly combining sub-detector images, especially the fluorescence emission difference (FED) technique. To improve the resolution and contrast of FED microscopy based on an array detector, we propose to associate sparse denoising with spatial adaptive estimation.

Super-resolved live-cell imaging using random illumination microscopy.

Current super-resolution microscopy (SRM) methods suffer from an intrinsic complexity that might curtail their routine use in cell biology. We describe here random illumination microscopy (RIM) for live-cell imaging at super-resolutions matching that of 3D structured illumination microscopy, in a robust fashion. Based on speckled illumination and statistical image reconstruction, easy to implement and user-friendly, RIM is unaffected by optical aberrations on the excitation side, linear to brightness, and compatible with multicolor live-cell imaging over extended periods of time.

High-resolution dynamic mapping of the C. elegans intestinal brush border.

The intestinal brush border is made of an array of microvilli that increases the membrane surface area for nutrient processing, absorption and host defense. Studies on mammalian cultured epithelial cells have uncovered some of the molecular players and physical constraints required to establish this apical specialized membrane. However, the building and maintenance of a brush border in vivo has not yet been investigated in detail.

C-terminal phosphorylation modulates ERM-1 localization and dynamics to control cortical actin organization and support lumen formation during development.

ERM proteins are conserved regulators of cortical membrane specialization that function as membrane-actin linkers and molecular hubs. The activity of ERM proteins requires a conformational switch from an inactive cytoplasmic form into an active membrane- and actin-bound form, which is thought to be mediated by sequential PIP binding and phosphorylation of a conserved C-terminal threonine residue. Here, we use the single ERM ortholog, ERM-1, to study the contribution of these regulatory events to ERM activity and tissue formation Using CRISPR/Cas9-generated mutant alleles, we demonstrate that a PIP-binding site is crucially required for ERM-1 function.

Simultaneous Regulation of Cytokinetic Furrow and Nucleus Positions by Cortical Tension Contributes to Proper DNA Segregation during Late Mitosis.

Coordinating mitotic spindle and cytokinetic furrow positioning is essential to ensure proper DNA segregation. Here, we present a novel mechanism, which corrects DNA segregation defects due to cytokinetic furrow mispositioning during the first division of C. elegans embryos.

A V0-ATPase-dependent apical trafficking pathway maintains the polarity of the intestinal absorptive membrane.

Intestine function relies on the strong polarity of intestinal epithelial cells and the array of microvilli forming a brush border at their luminal pole. Combining a genetic RNA interference (RNAi) screen with super-resolution imaging in the intestine, we found that the V0 sector of the vacuolar ATPase (V0-ATPase) controls a late apical trafficking step, involving Ras-related protein 11 (RAB-11) endosomes and the -ethylmaleimide-sensitive factor-attachment protein receptor (SNARE) synaptosome-associated protein 29 (SNAP-29), and is necessary to maintain the polarized localization of both apical polarity modules and brush border proteins. We show that the V0-ATPase pathway also genetically interacts with glycosphingolipids and clathrin in enterocyte polarity maintenance.

Force Transmission between Three Tissues Controls Bipolar Planar Polarity Establishment and Morphogenesis.

How tissues from different developmental origins interact to achieve coordinated morphogenesis at the level of a whole organism is a fundamental question in developmental biology. While biochemical signaling pathways controlling morphogenesis have been extensively studied [1-3], morphogenesis of epithelial tissues can also be directed by mechanotransduction pathways physically linking two tissues [4-8]. C.

Dynamic Formation of Microvillus Inclusions During Enterocyte Differentiation in -Deficient Intestinal Organoids.

Background & Aims: Microvillus inclusion disease (MVID) is a congenital intestinal malabsorption disorder caused by defective apical vesicular transport. Existing cellular models do not fully recapitulate this heterogeneous pathology. The aim of this study was to characterize 3-dimensional intestinal organoids that continuously generate polarized absorptive cells as an accessible and relevant model to investigate MVID.

Contractile forces at tricellular contacts modulate epithelial organization and monolayer integrity.

Monolayered epithelia are composed of tight cell assemblies that ensure polarized exchanges. EpCAM, an unconventional epithelial-specific cell adhesion molecule, is assumed to modulate epithelial morphogenesis in animal models, but little is known regarding its cellular functions. Inspired by the characterization of cellular defects in a rare EpCAM-related human intestinal disease, we find that the absence of EpCAM in enterocytes results in an aberrant apical domain.

The localisation of the apical Par/Cdc42 polarity module is specifically affected in microvillus inclusion disease.

Background Information: Microvillus inclusion disease (MVID) is a genetic disorder affecting intestinal absorption. It is caused by mutations in MYO5B or syntaxin 3 (STX3) affecting apical membrane trafficking. Morphologically, MVID is characterised by a depletion of apical microvilli and the formation of microvillus inclusions inside the cells, suggesting a loss of polarity.

PAR-4 and anillin regulate myosin to coordinate spindle and furrow position during asymmetric division.

During asymmetric cell division, the mitotic spindle and polarized myosin can both determine the position of the cytokinetic furrow. However, how cells coordinate signals from the spindle and myosin to ensure that cleavage occurs through the spindle midzone is unknown. Here, we identify a novel pathway that is essential to inhibit myosin and coordinate furrow and spindle positions during asymmetric division.

Adaptation of Cryo-Sectioning for IEM Labeling of Asymmetric Samples: A Study Using Caenorhabditis elegans.

Cryo-sectioning procedures, initially developed by Tokuyasu, have been successfully improved for tissues and cultured cells, enabling efficient protein localization on the ultrastructural level. Without a standard procedure applicable to any sample, currently existing protocols must be individually modified for each model organism or asymmetric sample. Here, we describe our method that enables reproducible cryo-sectioning of Caenorhabditis elegans larvae/adults and embryos.

Control of E-cadherin apical localisation and morphogenesis by a SOAP-1/AP-1/clathrin pathway in C. elegans epidermal cells.

E-cadherin (E-cad) is the main component of epithelial junctions in multicellular organisms, where it is essential for cell-cell adhesion. The localisation of E-cad is often strongly polarised in the apico-basal axis. However, the mechanisms required for its polarised distribution are still largely unknown.

GPSy: a cross-species gene prioritization system for conserved biological processes--application in male gamete development.

We present gene prioritization system (GPSy), a cross-species gene prioritization system that facilitates the arduous but critical task of prioritizing genes for follow-up functional analyses. GPSy's modular design with regard to species, data sets and scoring strategies enables users to formulate queries in a highly flexible manner. Currently, the system encompasses 20 topics related to conserved biological processes including male gamete development discussed in this article.

AP-1 is required for the maintenance of apico-basal polarity in the C. elegans intestine.

Epithelial tubes perform functions that are essential for the survival of multicellular organisms. Understanding how their polarised features are maintained is therefore crucial. By analysing the function of the clathrin adaptor AP-1 in the C.

Anticancer drug 5-fluorouracil induces reproductive and developmental defects in Caenorhabditis elegans.

In order to examine the chronic effects of anticancer drug 5-fluorouracil (5-FU) on reproduction and development, we exploited Caenorhabditis elegans as a model system. We demonstrate that 5-FU induces cell-cycle arrest and apoptosis of germline cells and reduces by approximately 30-40% the number of mitotic nuclei per gonad arm when compared to untreated worms. This drug also affects vulva development, some animals being vulvaless, as well as dysfunction of vulval and egg laying muscles leading to an 8-10 days delay in reproductive time.

[Sorting, recycling and WNT signaling: Wntless and retromer functions].

Cell-cell signaling is essential for the development of multi-cellular organisms. Indeed, membrane traffic is required for the correct sorting and function of receptors and ligands. In the past decades, many genetic screens performed in C.

High-pressure freezing provides insights into Weibel-Palade body biogenesis.

The Weibel-Palade bodies (WPBs) of endothelial cells play an important role in haemostasis and the initiation of inflammation, yet their biogenesis is poorly understood. Tubulation of their major content protein, von Willebrand factor (VWF), is crucial to WPB function, and so we investigated further the relationship between VWF tubule formation and WPB formation in human umbilical vein endothelial cells (HUVECs). By using high-pressure freezing and freeze substitution before electron microscopy, we visualised VWF tubules in the trans-Golgi network (TGN), as well as VWF subunits in vesicular structures.