Moreover, through in silico structural engineering of the tail fiber, we demonstrate PVCs' reprogrammability to target organisms beyond their natural substrates, including human cells and mice, with near-perfect efficiency approaching 100%. Lastly, we present compelling evidence that PVCs can load and deliver a broad spectrum of proteins, including Cas9, base editors, and toxins, into human cells, effectively illustrating their functional potential. PVCs, demonstrably programmable protein delivery vehicles, hold promise for applications in gene therapy, cancer treatment, and biocontrol.

Effective pancreatic ductal adenocarcinoma (PDA) therapies are urgently needed, given the escalating incidence and poor prognosis of this highly lethal malignancy. While the pursuit of targeting tumor metabolism has been a subject of extensive investigation for over a decade, the dynamic nature of tumor metabolism and the substantial potential for adverse effects have constrained this cancer-fighting strategy. learn more In human and mouse in vitro and in vivo models, we utilize genetic and pharmacological approaches to demonstrate PDA's unique reliance on de novo ornithine synthesis from glutamine. Ornithine aminotransferase (OAT) is a key mediator in polyamine synthesis, which is vital for tumor growth. Infancy is usually associated with a strong directional aspect of OAT activity, differing significantly from the usage of arginine-derived ornithine for the synthesis of polyamines in the majority of adult normal tissues and cancer types. Mutant KRAS provokes arginine depletion, resulting in a dependency that is observed within the PDA tumor microenvironment. Elevated expression of OAT and polyamine synthesis enzymes, triggered by activated KRAS, causes modifications to the transcriptome and open chromatin landscape in PDA tumor cells. The disparate reliance on OAT-mediated de novo ornithine synthesis between pancreatic cancer cells and normal tissue highlights a potential therapeutic avenue for treating pancreatic cancer, mitigating harmful effects.

A gasdermin-family protein, GSDMB, is cleaved by granzyme A, a cytotoxic lymphocyte-derived enzyme, leading to the pyroptotic demise of the target cell. The Shigella flexneri virulence factor IpaH78, a ubiquitin-ligase, has been reported with conflicting results regarding its influence on the degradation of both GSDMB and the gasdermin family member, GSDMD45. A list of sentences is the JSON schema for sentence 67. The precise mechanism by which IpaH78 interacts with both gasdermins remains unclear, and the role of GSDMB in pyroptosis has recently come under scrutiny. The crystal structure of the IpaH78-GSDMB complex is documented herein, highlighting IpaH78's specific interaction with the pore-forming domain of GSDMB. We elucidate that IpaH78 is directed towards human GSDMD, not mouse GSDMD, through a similar method. In contrast to other gasdermins, the full-length GSDMB structure reveals a more substantial autoinhibitory capacity. Multiple splicing isoforms of GSDMB are equally bound by IpaH78, leading to varying degrees of pyroptotic response. Exon 6's presence within the GSDMB isoforms dictates their pore-forming, pyroptotic activity. The 27-fold-symmetric GSDMB pore's structure, as observed via cryo-electron microscopy, is presented, coupled with a depiction of the conformational shifts that prompt its formation. Exon-6-derived components play a pivotal part in pore formation, as revealed by the structure, thereby elucidating the underlying cause of pyroptosis impairment in the non-canonical splicing variant, as observed in recent studies. Marked differences exist in isoform makeup across various cancer cell lines, closely aligning with the initiation and extent of pyroptosis following GZMA. Pathogenic bacteria and mRNA splicing exert a finely tuned regulation of GSDMB pore activity, as detailed in our study, revealing the structural underpinnings of this process.

In numerous areas, such as cloud physics, climate change, and cryopreservation, ice on Earth plays a critical role. Ice's role is influenced by the pattern of its formation and the resultant structural configuration. However, a thorough understanding of these matters is yet to be achieved. A noteworthy, longstanding discussion continues regarding whether water can freeze to form cubic ice, a currently unexplored phase within the phase diagram of common hexagonal ice. learn more A compilation of laboratory findings indicates that the prevalent understanding of this variation points to the challenge of recognizing cubic ice from stacking-disordered ice, a combination of cubic and hexagonal structures, as referenced in studies 7 through 11. We employ cryogenic transmission electron microscopy combined with low-dose imaging to demonstrate that cubic ice nucleates preferentially at low-temperature interfaces. This process leads to the separate crystallization of cubic and hexagonal ice from water vapor deposition at 102 Kelvin. Furthermore, we pinpoint a sequence of cubic-ice imperfections, encompassing two distinct stacking irregularities, thereby illuminating the structural evolution dynamics corroborated by molecular dynamics simulations. Transmission electron microscopy allows for the direct real-space imaging of ice formation and its dynamic behavior at the molecular level, offering opportunities in ice research at the molecular scale and potentially applicable to other hydrogen-bonding crystals.

For the fetus's sustenance and safety throughout pregnancy, the relationship between the placenta, the extraembryonic organ of the fetus, and the decidua, the uterine lining, is paramount. learn more The decidua serves as a target for extravillous trophoblast cells (EVTs), originating from placental villi, leading to the transformation of maternal arteries into high-conductance vessels. A key link between pre-eclampsia and other pregnancy problems is the compromised trophoblast invasion and arterial modification that take place in early pregnancy. A spatially resolved, multiomic single-cell atlas of the entire human maternal-fetal interface, encompassing the myometrium, has been generated, allowing for a comprehensive analysis of trophoblast differentiation trajectories. Our utilization of this cellular map enabled the inference of potential transcription factors driving EVT invasion, and we found these factors conserved in in vitro models of EVT differentiation from primary trophoblast organoids and trophoblast stem cells. Defining the transcriptomes of the terminal cell states in trophoblast-invaded placental bed giant cells (fused multinucleated extravillous trophoblasts) and endovascular extravillous trophoblasts (which form plugs inside maternal arteries) is our approach. We project the cell-cell communication events behind trophoblast invasion and placental bed giant cell development, and we propose a model that details the dual function of interstitial and endovascular extravillous trophoblasts in facilitating arterial transformation during early pregnancy. Our data collectively provide a detailed analysis of postimplantation trophoblast differentiation, enabling the creation of more relevant experimental models for the human placenta during early pregnancy.

Pyroptosis is a process facilitated by Gasdermins (GSDMs), pore-forming proteins, which are integral to host defense. Among GSDMs, GSDMB's uniqueness arises from its unusual lipid-binding profile and the continuing uncertainty surrounding its pyroptotic functionality. GSDMB's capacity for directly killing bacteria, a recently observed phenomenon, is mediated by its pore-forming action. The human-adapted intracellular enteropathogen Shigella employs IpaH78, a virulence effector, to outmaneuver GSDMB-mediated host defense by triggering ubiquitination and proteasomal degradation of GSDMB4. Cryo-EM structures of human GSDMB bound to Shigella IpaH78 and its pore are reported. The GSDMB-IpaH78 complex's structural arrangement demonstrates a three-residue motif of negatively charged residues within GSDMB to be the structural determinant recognized by IpaH78. Only human GSDMD, and not mouse GSDMD, exhibits this conserved motif, leading to the species-specificity of the IpaH78 effect. Alternative splicing regulates an interdomain linker within the GSDMB pore structure, functioning as a modulator for GSDMB pore creation. While GSDMB isoforms featuring a standard interdomain linker preserve normal pyroptotic activity, other isoforms display reduced or non-existent pyroptotic function. The molecular mechanisms of Shigella IpaH78's interaction with and targeting of GSDMs are examined in this work, and a structural component within GSDMB is identified as crucial for its pyroptotic activity.

Newly formed non-enveloped virions necessitate the destruction of the host cell to be released, signifying that these viruses possess mechanisms to induce cellular demise. Noroviruses represent a category of viruses; however, a causative mechanism for norovirus infection-associated cell death and lysis is presently undisclosed. Through investigation, we pinpoint the molecular mechanism behind norovirus-induced cellular demise. Norovirus-encoded NTPase NS3 was found to contain an N-terminal four-helix bundle domain that exhibits homology with the membrane-disruption domain of the pseudokinase mixed lineage kinase domain-like (MLKL) molecule. NS3's mitochondrial localization signal directly promotes its interaction with and subsequent damage to mitochondria, thus initiating cell death. Full-length NS3 protein, and a segment of the protein's N-terminus, both interacted with the mitochondrial membrane lipid cardiolipin, which led to membrane permeabilization and a subsequent mitochondrial dysfunction cascade. In mice, the NS3 protein's mitochondrial localization motif and N-terminal region were pivotal for cell death, viral release, and viral replication. The acquisition of a host MLKL-like pore-forming domain by noroviruses is indicative of an adaptive strategy to exploit mitochondrial malfunction and thus support viral egress.

Inorganic membranes, independent of organic and polymeric structures, may unlock advanced applications, such as separation, catalysis, sensors, memory devices, optical filters, and ionic conduction.