The Bacillus cereus toxin alveolysin disrupts the intestinal epithelial barrier by inducing microtubule disorganization through CFAP100

Targeted degradation of membrane and extracellular proteins with LYTACs

Targeted protein degradation technology has gained substantial momentum over the past two decades as a revolutionary strategy for eliminating pathogenic proteins that are otherwise refractory to treatment. Among the various approaches developed to harness the body's innate protein homeostasis mechanisms for this purpose, lysosome targeting chimeras (LYTACs) that exploit the lysosomal degradation pathway by coupling the target proteins with lysosome-trafficking receptors represent the latest innovation. These chimeras are uniquely tailored to degrade proteins that are membrane-bound and extracellular, encompassing approximately 40% of all proteome. Several novel LYTAC formulas have been developed recently, providing valuable insights for the design and development of therapeutic degraders. This review delineates the recent progresses of LYTAC technology, its practical applications, and the factors that dictate target degradation efficiency. The potential and emerging trends of this technology are discussed as well. LYTAC technology offers a promising avenue for targeted protein degradation, potentially revolutionizing the therapeutic landscape for numerous diseases.

Strategies of bacterial detection by inflammasomes

Mammalian innate immunity is regulated by pattern-recognition receptors (PRRs) and guard proteins, which use distinct strategies to detect infections. PRRs detect bacterial molecules directly, whereas guards detect host cell manipulations by microbial virulence factors. Despite sensing infection through different mechanisms, both classes of innate immune sensors can activate the inflammasome, an immune complex that can mediate cell death and inflammation. Inflammasome-mediated immune responses are crucial for host defense against many bacterial pathogens and prevent invasion by non-pathogenic organisms. In this review, we discuss the mechanisms by which inflammasomes are stimulated by PRRs and guards during bacterial infection, and the strategies used by virulent bacteria to evade inflammasome-mediated immunity.

Liquid-liquid phase separation of microtubule-binding proteins in the regulation of spindle assembly

Cell division is a highly regulated process essential for the accurate segregation of chromosomes. Central to this process is the assembly of a bipolar mitotic spindle, a highly dynamic microtubule (MT)-based structure responsible for chromosome movement. The nucleation and dynamics of MTs are intricately regulated by MT-binding proteins. Over the recent years, various MT-binding proteins have been reported to undergo liquid-liquid phase separation, forming either single- or multi-component condensates on MTs. Herein, we provide a comprehensive summary of the phase separation characteristics of these proteins. We underscore their critical roles in MT nucleation, spindle assembly and kinetochore-MT attachment during the cell division process. Furthermore, we discuss the current challenges and various remaining unsolved problems, highlights the ongoing research efforts aimed at a deeper understanding of the role of the phase separation process during spindle assembly and orientation. Our review aims to contribute to the collective knowledge in this area and stimulate further investigations that will enhance our comprehension of the intricate mechanisms governing cell division.

Multifaceted roles of PDCD6 both within and outside the cell

Programmed cell death protein 6 (PDCD6) is an evolutionarily conserved Ca2+-binding protein. PDCD6 is involved in regulating multifaceted and pleiotropic cellular processes in different cellular compartments. For instance, nuclear PDCD6 regulates apoptosis and alternative splicing. PDCD6 is required for coat protein complex II-dependent endoplasmic reticulum-to-Golgi apparatus vesicular transport in the cytoplasm. Recent advances suggest that cytoplasmic PDCD6 is involved in the regulation of cytoskeletal dynamics and innate immune responses. Additionally, membranous PDCD6 participates in membrane repair through endosomal sorting complex required for transport complex-dependent membrane budding. Interestingly, extracellular vesicles are rich in PDCD6. Moreover, abnormal expression of PDCD6 is closely associated with many diseases, especially cancer. PDCD6 is therefore a multifaceted but pivotal protein in vivo. To gain a more comprehensive understanding of PDCD6 functions and to focus and stimulate PDCD6 research, this review summarizes key developments in its role in different subcellular compartments, processes, and pathologies.

Thrombus Tango: Hypercoagulable State With a Right Atrial Mass and Superimposed Persistent Bacteremia

Bacillus cereus is an uncommon nosocomial bacteria, typically dismissed as a contaminant. This case is a unique scenario in which B. cereus bacteremia persisted despite appropriate treatment. Further investigation revealed the presence of a right atrial thrombus believed to harbor a biofilm responsible for the sustained bacteremia. Clearance of the thrombus using the AngioVac system (AngioDynamics, Inc., Latham, NY) led to the resolution of blood cultures, and subsequently, the patient was discharged with a six-week course of intravenous (IV) antibiotics.

Restraining the power of Proteolysis Targeting Chimeras in the cage: A necessary and important refinement for therapeutic safety

Proteolysis Targeting Chimeras (PROTACs) represent a significant advancement in therapeutic drug development by leveraging the ubiquitin-proteasome system to enable targeted protein degradation, particularly impacting oncology. This review delves into the various types of PROTACs, such as peptide-based, nucleic acid-based, and small molecule PROTACs, each addressing distinct challenges in protein degradation. It also discusses innovative strategies like bridged PROTACs and conditional switch-activated PROTACs, offering precise targeting of previously "undruggable" proteins. The potential of PROTACs extends beyond oncology, with ongoing research and technological advancements needed to maximize their therapeutic potential. Future progress in this field relies on interdisciplinary collaboration and the integration of advanced computational tools to open new treatment avenues across various diseases.

Dynamic changes of endothelial and stromal cilia are required for the maintenance of corneal homeostasis

Primary cilia are distributed extensively within the corneal epithelium and endothelium. However, the presence of cilia in the corneal stroma and the dynamic changes and roles of endothelial and stromal cilia in corneal homeostasis remain largely unknown. Here, we present compelling evidence for the presence of primary cilia in the corneal stroma, both in vivo and in vitro. We also demonstrate dynamic changes of both endothelial and stromal cilia during corneal development. In addition, our data show that cryoinjury triggers dramatic cilium formation in the corneal endothelium and stroma. Furthermore, depletion of cilia in mutant mice lacking intraflagellar transport protein 88 compromises the corneal endothelial capacity to establish the effective tissue barrier, leading to an upregulation of α-smooth muscle actin within the corneal stroma in response to cryoinjury. These observations underscore the essential involvement of corneal endothelial and stromal cilia in maintaining corneal homeostasis and provide an innovative strategy for the treatment of corneal injuries and diseases.

Dynein Light Intermediate Chains Exhibit Different Arginine Methylation Patterns

BACKGROUND

The motor protein dynein is integral to retrograde transport along microtubules and interacts with numerous cargoes through the recruitment of cargo-specific adaptor proteins. This interaction is mediated by dynein light intermediate chain subunits LIC1 (DYNC1LI1) and LIC2 (DYNC1LI2), which govern the adaptor binding and are present in distinct dynein complexes with overlapping and unique functions.

METHODS

Using bioinformatics, we analyzed the C-terminal domains (CTDs) of LIC1 and LIC2, revealing similar structural features but diverse post-translational modifications (PTMs). The methylation status of LIC2 and the proteins involved in this modification were examined through immunoprecipitation and immunoblotting analyses. The specific methylation sites on LIC2 were identified through a site-directed mutagenesis analysis, contributing to a deeper understanding of the regulatory mechanisms of the dynein complex.

RESULTS

We found that LIC2 is specifically methylated at the arginine 397 residue, a reaction that is catalyzed by protein arginine methyltransferase 1 (PRMT1).

CONCLUSIONS

The distinct PTMs of the LIC subunits offer a versatile mechanism for dynein to transport diverse cargoes efficiently. Understanding how these PTMs influence the functions of LIC2, and how they differ from LIC1, is crucial for elucidating the role of dynein-related transport pathways in a range of diseases. The discovery of the arginine 397 methylation site on LIC2 enhances our insight into the regulatory PTMs of dynein functions.

INPP5E Regulates the Distribution of Phospholipids on Cilia in RPE1 Cells

BACKGROUND

Primary cilia are static microtubule-based structures protruding from the cell surface and present on most vertebrate cells. The appropriate localization of phospholipids is essential for cilia formation and stability. INPP5E is a cilia-localized inositol 5-phosphatase; its deletion alters the phosphoinositide composition in the ciliary membrane, disrupting ciliary function.

METHODS

The EGFP-2xP4MSidM, PHPLCδ1-EGFP, and SMO-tRFP plasmids were constructed by the Gateway system to establish a stable RPE1 cell line. The INPP5E KO RPE1 cell line was constructed with the CRISPR/Cas9 system. The localization of INPP5E and the distribution of PI(4,5)P2 and PI4P were examined by immunofluorescence microscopy. The fluorescence intensity co-localized with cilia was quantified by ImageJ.

RESULTS

In RPE1 cells, PI4P is localized at the ciliary membrane, whereas PI(4,5)P2 is localized at the base of cilia. Knocking down or knocking out INPP5E alters this distribution, resulting in the distribution of PI(4,5)P2 along the ciliary membrane and the disappearance of PI4P from the cilia. Meanwhile, PI(4,5)P2 is located in the ciliary membrane labeled by SMO-tRFP.

CONCLUSIONS

INPP5E regulates the distribution of phosphoinositide on cilia. PI(4,5)P2 localizes at the ciliary membrane labeled with SMO-tRFP, indicating that ciliary pocket membrane contains PI(4,5)P2, and phosphoinositide composition in early membrane structures may differ from that in mature ciliary membrane.

CCL2-CCR2 signaling axis in obesity and metabolic diseases

Obesity and metabolic diseases, such as insulin resistance, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular ailments, represent formidable global health challenges, bearing considerable implications for both morbidity and mortality rates. It has become increasingly evident that chronic, low-grade inflammation plays a pivotal role in the genesis and advancement of these conditions. The involvement of C-C chemokine ligand 2 (CCL2) and its corresponding receptor, C-C chemokine receptor 2 (CCR2), has been extensively documented in numerous inflammatory maladies. Recent evidence indicates that the CCL2/CCR2 pathway extends beyond immune cell recruitment and inflammation, exerting a notable influence on the genesis and progression of metabolic syndrome. The present review seeks to furnish a comprehensive exposition of the CCL2-CCR2 signaling axis within the context of obesity and metabolic disorders, elucidating its molecular mechanisms, functional roles, and therapeutic implications.

A Modified Tridecapeptide Probe for Imaging Cell Junction

Cell junctions, which are typically associated with dynamic cytoskeletons, are essential for a wide range of cellular activities, including cell migration, cell communication, barrier function and signal transduction. Observing cell junctions in real-time can help us understand the mechanisms by which they regulate these cellular activities. This study examined the binding capacity of a modified tridecapeptide from Connexin 43 (Cx43) to the cell junction protein zonula occludens-1 (ZO-1). The goal was to create a fluorescent peptide that can label cell junctions. A cell-penetrating peptide was linked to the modified tridecapeptide. The heterotrimeric peptide molecule was then synthesized. The binding of the modified tridecapeptide was tested using pulldown and immunoprecipitation assays. The ability of the peptide to label cell junctions was assessed by adding it to fixed or live Caco-2 cells. The testing assays revealed that the Cx43-derived peptide can bind to ZO-1. Additionally, the peptide was able to label cell junctions of fixed cells, although no obvious cell junction labeling was observed clearly in live cells, probably due to the inadequate affinity. These findings suggest that labeling cell junctions using a peptide-based strategy is feasible. Further efforts to improve its affinity are warranted in the future.