Histone H3 clipping is a novel signature of human neutrophil extracellular traps.

Neutrophils are critical to host defence, executing diverse strategies to perform their antimicrobial and regulatory functions. One tactic is the production of neutrophil extracellular traps (NETs). In response to certain stimuli, neutrophils decondense their lobulated nucleus and release chromatin into the extracellular space through a process called NETosis.

Hemocytes are essential for Drosophila melanogaster post-embryonic development, independent of control of the microbiota.

Proven roles for hemocytes (blood cells) have expanded beyond the control of infections in Drosophila. Despite this, the crucial role of hemocytes in post-embryonic development has long thought to be limited to control of microorganisms during metamorphosis. This has previously been shown by rescue of adult development in hemocyte-ablation models under germ-free conditions.

Gasdermin D plays a vital role in the generation of neutrophil extracellular traps.

The death of a cell is an inevitable part of its biology. During homeostasis, most cells die through apoptosis. If homeostasis is disturbed, cell death can switch to proinflammatory forms of death, such as necroptosis, pyroptosis, or NETosis.

Diverse stimuli engage different neutrophil extracellular trap pathways.

Neutrophils release neutrophil extracellular traps (NETs) which ensnare pathogens and have pathogenic functions in diverse diseases. We examined the NETosis pathways induced by five stimuli; PMA, the calcium ionophore A23187, nigericin, and Group B Streptococcus. We studied NET production in neutrophils from healthy donors with inhibitors of molecules crucial to PMA-induced NETs including protein kinase C, calcium, reactive oxygen species, the enzymes myeloperoxidase (MPO) and neutrophil elastase.

In vivo super-resolution RESOLFT microscopy of Drosophila melanogaster.

Despite remarkable developments in diffraction unlimited super-resolution microscopy, in vivo nanoscopy of tissues and model organisms is still not satisfactorily established and rarely realized. RESOLFT nanoscopy is particularly suited for live cell imaging because it requires relatively low light levels to overcome the diffraction barrier. Previously, we introduced the reversibly switchable fluorescent protein rsEGFP2, which facilitated fast RESOLFT nanoscopy (Grotjohann et al.

Histone supply regulates S phase timing and cell cycle progression.

Eukaryotes package DNA into nucleosomes that contain a core of histone proteins. During DNA replication, nucleosomes are disrupted and re-assembled with newly synthesized histones and DNA. Despite much progress, it is still unclear why higher eukaryotes contain multiple core histone genes, how chromatin assembly is controlled, and how these processes are coordinated with cell cycle progression.

Bällchen participates in proliferation control and prevents the differentiation of Drosophila melanogaster neuronal stem cells.

Stem cells continuously generate differentiating daughter cells and are essential for tissue homeostasis and development. Their capacity to self-renew as undifferentiated and actively dividing cells is controlled by either external signals from a cellular environment, the stem cell niche, or asymmetric distribution of cell fate determinants during cell division. Here we report that the protein kinase Bällchen (BALL) is required to prevent differentiation as well as to maintain normal proliferation of neuronal stem cells of Drosophila melanogaster, called neuroblasts.

Bällchen is required for self-renewal of germline stem cells in Drosophila melanogaster.

Self-renewing stem cells are pools of undifferentiated cells, which are maintained in cellular niche environments by distinct tissue-specific signalling pathways. In Drosophila melanogaster, female germline stem cells (GSCs) are maintained in a somatic niche of the gonads by BMP signalling. Here we report a novel function of the Drosophila kinase Bällchen (BALL), showing that its cell autonomous role is to maintain the self-renewing capacity of female GSCs independent of BMP signalling.

A histone mutant reproduces the phenotype caused by loss of histone-modifying factor Polycomb.

Although many metazoan enzymes that add or remove specific modifications on histone proteins are essential transcriptional regulators, the functional significance of posttranslational modifications on histone proteins is not well understood. Here, we show in Drosophila that a point mutation in lysine 27 of histone H3 (H3-K27) fails to repress transcription of genes that are normally repressed by Polycomb repressive complex 2 (PRC2), the methyltransferase that modifies H3-K27. Moreover, differentiated H3-K27 mutant cells show homeotic transformations like those seen in PRC2 mutant cells.

Pre-fibrillar α-synuclein mutants cause Parkinson's disease-like non-motor symptoms in Drosophila.

Parkinson's disease (PD) is linked to the formation of insoluble fibrillar aggregates of the presynaptic protein α-Synuclein (αS) in neurons. The appearance of such aggregates coincides with severe motor deficits in human patients. These deficits are often preceded by non-motor symptoms such as sleep-related problems in the patients.

A genetic system to assess in vivo the functions of histones and histone modifications in higher eukaryotes.

Despite the fundamental role of canonical histones in nucleosome structure, there is no experimental system for higher eukaryotes in which basic questions about histone function can be directly addressed. We developed a new genetic tool for Drosophila melanogaster in which the canonical histone complement can be replaced with multiple copies of experimentally modified histone transgenes. This new histone-replacement system provides a well-defined and direct cellular assay system for histone function with which to critically test models in chromatin biology dealing with chromatin assembly, variant histone functions and the biological significance of distinct histone modifications in a multicellular organism.

Pre-fibrillar alpha-synuclein variants with impaired beta-structure increase neurotoxicity in Parkinson's disease models.

The relation of alpha-synuclein (alphaS) aggregation to Parkinson's disease (PD) has long been recognized, but the mechanism of toxicity, the pathogenic species and its molecular properties are yet to be identified. To obtain insight into the function different aggregated alphaS species have in neurotoxicity in vivo, we generated alphaS variants by a structure-based rational design. Biophysical analysis revealed that the alphaS mutants have a reduced fibrillization propensity, but form increased amounts of soluble oligomers.

Structure predictions and interaction studies indicate homology of separase N-terminal regulatory domains and Drosophila THR.

The final resolution of sister chromatid cohesion during mitotic and meiotic divisions is mediated by activation of separase which cleaves a cohesin complex subunit. The structural basis of separase regulation is unknown. Separases from different eukaryotes share almost no sequence similarity, especially within the large N-terminal domain that precedes the protease domain except in Drosophila melanogaster.

Proteolytic cleavage of the THR subunit during anaphase limits Drosophila separase function.

Sister-chromatid separation in mitosis requires proteolytic cleavage of a cohesin subunit. Separase, the corresponding protease, is activated at the metaphase-to-anaphase transition. Activation involves proteolysis of an inhibitory subunit, securin, following ubiquitination mediated by the anaphase-promoting complex/cyclosome.