clock-scan-protocol-for-image-analysis-imagej-plugins

Clock Scan Protocol for Image Analysis: ImageJ Plugins

The clock scan protocol for image analysis is an efficient tool to quantify the average pixel intensity within, at the border, and outside (background) a ...

Max Plank Institute for Infection Biology

The epidermis and internal tubular organs, such as gut and lungs, are exposed to a hostile environment. They form an extracellular matrix to provide epithelial integrity and to prevent contact with pathogens and toxins. In arthropods, the cuticle protects, shapes, and enables the functioning of organs. During development, cuticle matrix is shielded from premature degradation; however, underlying molecular mechanisms are poorly understood. Previously, we identified the conserved obstructor multigene-family, which encodes chitin-binding proteins. Here we show that Obstructor-A is required for extracellular matrix dynamics in cuticle forming organs. Loss of obstructor-A causes severe defects during cuticle molting, wound protection, tube expansion and larval growth control. We found that Obstructor-A interacts and forms a core complex with the polysaccharide chitin, the cuticle modifier Knickkopf and the chitin deacetylase Serpentine. Knickkopf protects chitin from chitinase-dependent degradation and deacetylase enzymes ensure extracellular matrix maturation. We provide evidence that Obstructor-A is required to control the presence of Knickkopf and Serpentine in the extracellular matrix. We propose a model suggesting that Obstructor-A coordinates the core complex for extracellular matrix protection from premature degradation. This mechanism enables exoskeletal molting, tube expansion, and epithelial integrity. The evolutionary conservation suggests a common role of Obstructor-A and homologs in coordinating extracellular matrix protection in epithelial tissues of chitinous invertebrates.

Obstructor-A is required for epithelial extracellular matrix dynamics, exoskeleton function, and tubulogenesis.

Long-term proliferating, DH JH -rearranged mouse precursor B-cell lines have previously been established in serum- and IL-7-containing media from fetal liver, but not from bone marrow. Serum and stromal cells expose these pre-B cells to undefined factors, hampering accurate analyses of ligand-dependent signaling, which controls pre-B cell proliferation, survival, residence and migration. Here, we describe a novel serum-free, stromal cell-free culture system, which allows us to establish and maintain pre-B cells not only from fetal liver, but also from bone marrow with practically identical efficiencies in proliferation, cloning and differentiation. Surprisingly, recombinant kit-ligand, also called stem cell factor, produced as a kit-ligand-Fc fusion protein, suffices to replace stromal cells and serum, provided that it is presented to cultured pre-B cells in an optimal density in plate-bound, insolubilized, potentially crosslinking form. Additional recombinant CXCL12 and fibronectin have a minor influence on the establishment and maintenance of pre-B cell lines and clones from fetal liver, but are necessary to establish such cell lines from bone marrow.

Article	Year
Obstructor-A is required for epithelial extracellular matrix dynamics, exoskeleton function, and tubulogenesis. The Journal of biological chemistry\| PubMed ID: 22544743	2012
IL-7 and immobilized Kit-ligand stimulate serum- and stromal cell-free cultures of precursor B-cell lines and clones. European journal of immunology\| PubMed ID: 27739072	2017

Georg Petkau

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