Targeted Activation of Programmed Cell Death Pathways by Optogenetics.

Regulated cell death is an important biological process by which an organism removes unwanted, malignant, or infected cells. Although it has become clear that different forms of regulated cell death exist, it remains difficult to compare their consequences at the cellular and tissue level as they are induced by different stimuli and proceed with different kinetics. Moreover, it was so far difficult to target and induce cell death in selected cells within cell populations or complex tissues without affecting its neighbors.

CCDC134 controls TLR biogenesis through the ER chaperone Gp96.

Toll-like receptors (TLRs) are central to initiate immune responses against invading pathogens. To ensure host defense while avoiding aberrant activation leading to pathogenic inflammation and autoimmune diseases, TLRs are tightly controlled by multilevel regulatory mechanisms. Through a loss-of-function genetic screen in a reporter cell line engineered to undergo cell death upon TLR7-induced IRF5 activation, we identified here CCDC134 as an essential factor for TLR responses.

Viral-bacterial co-infections screen in vitro reveals molecular processes affecting pathogen proliferation and host cell viability.

The broadening of accessible methodologies has enabled mechanistic insights into single-pathogen infections, yet the molecular mechanisms underlying co-infections remain largely elusive, despite their clinical frequency and relevance, generally exacerbating symptom severity and fatality. Here, we describe an unbiased in vitro screening of pairwise co-infections in a murine macrophage model, quantifying pathogen proliferation and host cell death in parallel over time. The screen revealed that the majority of interactions are antagonistic for both metrics, highlighting general patterns depending on the pathogen virulence strategy.

NLRP1-dependent activation of Gasdermin D in neutrophils controls cutaneous leishmaniasis.

Intracellular pathogens that replicate in host myeloid cells have devised ways to inhibit the cell's killing machinery. Pyroptosis is one of the host strategies used to reduce the pathogen replicating niche and thereby control its expansion. The intracellular Leishmania parasites can survive and use neutrophils as a silent entry niche, favoring subsequent parasite dissemination into the host.

Gasdermins as evolutionarily conserved executors of inflammation and cell death.

The gasdermins are a family of pore-forming proteins that have recently emerged as executors of pyroptosis, a lytic form of cell death that is induced by the innate immune system to eradicate infected or malignant cells. Mammalian gasdermins comprise a cytotoxic N-terminal domain, a flexible linker and a C-terminal repressor domain. Proteolytic cleavage in the linker releases the cytotoxic domain, thereby allowing it to form β-barrel membrane pores.

Programmed cell death: NINJ1 and mechanisms of plasma membrane rupture.

Lytic cell death culminates in cell swelling and plasma membrane rupture (PMR). The cellular contents released, including proteins, metabolites, and nucleic acids, can act as danger signals and induce inflammation. During regulated cell death (RCD), lysis is actively initiated and can be preceded by an initial loss of membrane integrity caused by pore-forming proteins, allowing small molecules and cytokines to exit the cell.

NINJ1 induces plasma membrane rupture and release of damage-associated molecular pattern molecules during ferroptosis.

Ferroptosis is a regulated form of necrotic cell death caused by iron-dependent accumulation of oxidized phospholipids in cellular membranes, culminating in plasma membrane rupture (PMR) and cell lysis. PMR is also a hallmark of other types of programmed necrosis, such as pyroptosis and necroptosis, where it is initiated by dedicated pore-forming cell death-executing factors. However, whether ferroptosis-associated PMR is also actively executed by proteins or driven by osmotic pressure remains unknown.

Exome sequencing improves the molecular diagnostics of paediatric unexplained neurodevelopmental disorders.

Background: Neurodevelopmental disorders (NDDs) and/or associated multiple congenital abnormalities (MCAs) represent a genetically heterogeneous group of conditions with an adverse prognosis for the quality of intellectual and social abilities and common daily functioning. The rapid development of exome sequencing (ES) techniques, together with trio-based analysis, nowadays leads to up to 50% diagnostic yield. Therefore, it is considered as the state-of-the-art approach in these diagnoses.

Gasdermin D is the only Gasdermin that provides protection against acute gut infection in mice.

Gasdermins (GSDMs) share a common functional domain structure and are best known for their capacity to form membrane pores. These pores are hallmarks of a specific form of cell death called pyroptosis and mediate the secretion of pro-inflammatory cytokines such as interleukin 1β (IL1β) and interleukin 18 (IL18). Thereby, Gasdermins have been implicated in various immune responses against cancer and infectious diseases such as acute Typhimurium (Tm) gut infection.

E-selectin-mediated rapid NLRP3 inflammasome activation regulates S100A8/S100A9 release from neutrophils via transient gasdermin D pore formation.

S100A8/S100A9 is a proinflammatory mediator released by myeloid cells during many acute and chronic inflammatory disorders. However, the precise mechanism of its release from the cytosolic compartment of neutrophils is unclear. Here, we show that E-selectin-induced rapid S100A8/S100A9 release during inflammation occurs in an NLRP3 inflammasome-dependent fashion.

Selective induction of programmed cell death using synthetic biology tools.

Regulated cell death (RCD) controls the removal of dispensable, infected or malignant cells, and is thus essential for development, homeostasis and immunity of multicellular organisms. Over the last years different forms of RCD have been described (among them apoptosis, necroptosis, pyroptosis and ferroptosis), and the cellular signaling pathways that control their induction and execution have been characterized at the molecular level. It has also become apparent that different forms of RCD differ in their capacity to elicit inflammation or an immune response, and that RCD pathways show a remarkable plasticity.

NLRP12 senses heme and PAMPs to drive necrotic cell death and inflammation.

Red blood cell rupture (hemolysis) activates innate immunity and inflammation by releasing heme. Sundaram et al. implicate the immune sensor NLRP12 in hemolytic disease, showing that it controls necrotic cell death induction in response to heme combined with pathogen-associated molecules.

Changes on chromosome 11p15.5 as specific marker for embryonal rhabdomyosarcoma?

Rhabdomyosarcomas (RMS) constitute a heterogeneous spectrum of tumors with respect to clinical behavior and tumor morphology. The paternal uniparental disomy (pUPD) of 11p15.5 is a molecular change described mainly in embryonal RMS.

Optogenetic Induction of Pyroptosis, Necroptosis, and Apoptosis in Mammalian Cell Lines.

Regulated cell death plays a key role in immunity, development, and homeostasis, but is also associated with a number of pathologies such as autoinflammatory and neurodegenerative diseases and cancer. However, despite the extensive mechanistic research of different cell death modalities, the direct comparison of different forms of cell death and their consequences on the cellular and tissue level remain poorly characterized. Comparative studies are hindered by the mechanistic and kinetic differences between cell death modalities, as well as the inability to selectively induce different cell death programs in an individual cell within cell populations or tissues.

Unconventional protein secretion by gasdermin pores.

Unconventional protein secretion (UPS) allows the release of specific leaderless proteins independently of the classical endoplasmic reticulum (ER)-Golgi secretory pathway. While it remains one of the least understood mechanisms in cell biology, UPS plays an essential role in immunity as it controls the release of the IL-1 family of cytokines, which coordinate host defense and inflammatory responses. The unconventional secretion of IL-1β and IL-18, the two most prominent members of the IL-1 family, is initiated by inflammasome complexes - cytosolic signaling platforms that are assembled in response to infectious or noxious stimuli.

Structural basis of NINJ1-mediated plasma membrane rupture in cell death.

Eukaryotic cells can undergo different forms of programmed cell death, many of which culminate in plasma membrane rupture as the defining terminal event. Plasma membrane rupture was long thought to be driven by osmotic pressure, but it has recently been shown to be in many cases an active process, mediated by the protein ninjurin-1 (NINJ1). Here we resolve the structure of NINJ1 and the mechanism by which it ruptures membranes.

Unusual case of inflammatory rhabdomyoblastic tumor in a pediatric patient.

Inflammatory rhabdomyoblastic tumor (IRMT) is a rare, recently described skeletal muscle neoplasm of uncertain malignant potential. We report an unusual tumor in the right arm of a 5-year-old boy, which is the first case of a pediatric IRMT. Immunohistochemically, most cells in the tumor were positive for CD163 and CD68 staining.

Apoptotic cell death in disease-Current understanding of the NCCD 2023.

Apoptosis is a form of regulated cell death (RCD) that involves proteases of the caspase family. Pharmacological and genetic strategies that experimentally inhibit or delay apoptosis in mammalian systems have elucidated the key contribution of this process not only to (post-)embryonic development and adult tissue homeostasis, but also to the etiology of multiple human disorders. Consistent with this notion, while defects in the molecular machinery for apoptotic cell death impair organismal development and promote oncogenesis, the unwarranted activation of apoptosis promotes cell loss and tissue damage in the context of various neurological, cardiovascular, renal, hepatic, infectious, neoplastic and inflammatory conditions.

Caspase-4 Activation and Recruitment to Intracellular Gram-Negative Bacteria.

The non-canonical inflammasome pathway functions as the primary cytosolic innate immune detection mechanism for Gram-negative bacterial lipopolysaccharide (LPS) in human and mouse cells and controls the proteolytic activation of the cell death executor gasdermin D (GSDMD). The main effectors of this pathways are the inflammatory proteases caspase-11 in mice and caspase-4/caspase-5 in humans. These caspases have been shown to bind LPS directly; however, the interaction between LPS and caspase-4/caspase-11 requires a set of interferon (IFN)-inducible GTPases, known as guanylate-binding proteins (GBPs).

A unique case of Bloom syndrome with a combination of genetic hits: A lesson from trio‑based exome sequencing: A case report.

Pathogenic variants affecting the gene are responsible for the manifestation of extremely rare cancer‑predisposing Bloom syndrome. The present study reports on a case of an infant with a congenital hypotrophy, short stature and abnormal facial appearance. Initially she was examined using a routine molecular diagnostic algorithm, including the cytogenetic analysis of her karyotype, microarray analysis and methylation‑specific MLPA, however, she remained undiagnosed on a molecular level.