Membrane blebbing during apoptosis results from caspase-mediated activation of ROCK I

Rho-associated protein kinase 1 inhibition in hepatocytes attenuates nonalcoholic steatohepatitis

BACKGROUND

NASH is the progressive form of NAFLD characterized by lipotoxicity, hepatocyte injury, tissue inflammation, and fibrosis. Previously, Rho-associated protein kinase (ROCK) 1 has been implicated in lipotoxic signaling in hepatocytes in vitro and high-fat diet-induced lipogenesis in vivo. However, whether ROCK1 plays a role in liver inflammation and fibrosis during NASH is unclear. Here, we hypothesized that pathogenic activation of ROCK1 promotes murine NASH pathogenesis.

METHODS AND RESULTS

Patients with NASH had increased hepatic ROCK1 expression compared with patients with fatty liver. Similarly, hepatic ROCK1 levels and activity were increased in mice with NASH induced by a western-like diet that is high in fat, fructose, and cholesterol (FFC). Hepatocyte-specific ROCK1 knockout mice on the FFC diet displayed a decrease in liver steatosis, hepatic cell death, liver inflammation, and fibrosis compared with littermate FFC-fed controls. Mechanistically, these effects were associated with a significant attenuation of myeloid cell recruitment. Interestingly, myeloid cell-specific ROCK1 deletion did not affect NASH development in FFC-fed mice. To explore the therapeutic opportunities, mice with established NASH received ROCKi, a novel small molecule kinase inhibitor of ROCK1/2, which preferentially accumulates in liver tissue. ROCK inhibitor treatment ameliorated insulin resistance and decreased liver injury, inflammation, and fibrosis.

CONCLUSIONS

Genetic or pharmacologic inhibition of ROCK1 activity attenuates murine NASH, suggesting that ROCK1 may be a therapeutic target for treating human NASH.

Orchestration of Mitochondrial Function and Remodeling by Post-Translational Modifications Provide Insight into Mechanisms of Viral Infection

The regulation of mitochondria structure and function is at the core of numerous viral infections. Acting in support of the host or of virus replication, mitochondria regulation facilitates control of energy metabolism, apoptosis, and immune signaling. Accumulating studies have pointed to post-translational modification (PTM) of mitochondrial proteins as a critical component of such regulatory mechanisms. Mitochondrial PTMs have been implicated in the pathology of several diseases and emerging evidence is starting to highlight essential roles in the context of viral infections. Here, we provide an overview of the growing arsenal of PTMs decorating mitochondrial proteins and their possible contribution to the infection-induced modulation of bioenergetics, apoptosis, and immune responses. We further consider links between PTM changes and mitochondrial structure remodeling, as well as the enzymatic and non-enzymatic mechanisms underlying mitochondrial PTM regulation. Finally, we highlight some of the methods, including mass spectrometry-based analyses, available for the identification, prioritization, and mechanistic interrogation of PTMs.

Surface-Engineered Extracellular Vesicles in Cancer Immunotherapy

Extracellular vesicles (EVs) are lipid bilayer-enclosed bodies secreted by all cell types. EVs carry bioactive materials, such as proteins, lipids, metabolites, and nucleic acids, to communicate and elicit functional alterations and phenotypic changes in the counterpart stromal cells. In cancer, cells secrete EVs to shape a tumor-promoting niche. Tumor-secreted EVs mediate communications with immune cells that determine the fate of anti-tumor therapeutic effectiveness. Surface engineering of EVs has emerged as a promising tool for the modulation of tumor microenvironments for cancer immunotherapy. Modification of EVs' surface with various molecules, such as antibodies, peptides, and proteins, can enhance their targeting specificity, immunogenicity, biodistribution, and pharmacokinetics. The diverse approaches sought for engineering EV surfaces can be categorized as physical, chemical, and genetic engineering strategies. The choice of method depends on the specific application and desired outcome. Each has its advantages and disadvantages. This review lends a bird's-eye view of the recent progress in these approaches with respect to their rational implications in the immunomodulation of tumor microenvironments (TME) from pro-tumorigenic to anti-tumorigenic ones. The strategies for modulating TME using targeted EVs, their advantages, current limitations, and future directions are discussed.

The Effects of Programmed Cell Death of Mesenchymal Stem Cells on the Development of Liver Fibrosis

Mesenchymal stem cells have shown noticeable potential for unlimited self-renewal. They can differentiate into specific somatic cells, integrate into target tissues via cell-cell contact, paracrine effects, exosomes, and other processes and then regulate the target cells and tissues. Studies have demonstrated that transplantation of MSCs could decrease the expression and concentration of collagen in the liver, thereby reducing liver fibrosis. A growing body of evidence indicates that apoptotic MSCs could inhibit harmful immune responses and reduce inflammatory responses more effectively than viable MSCs. Accumulating evidence suggests that mitochondrial transfer from MSCs is a novel strategy for the regeneration of various damaged cells via the rescue of their respiratory activities. This study is aimed at reviewing the functions of MSCs and the related roles of the programmed cell death of MSCs, including autophagy, apoptosis, pyroptosis, and ferroptosis, as well as the regulatory pathogenic mechanisms of MSCs in liver fibrosis. Research has demonstrated that the miR-200B-3p gene is differentially expressed gene between LF and normal liver samples, and that the miR-200B-3p gene expression is positively correlated with the degree of liver fibrosis, suggesting that MSCs could inhibit liver fibrosis through pyroptosis. It was confirmed that circulating monocytes could deliver MSC-derived immunomodulatory molecules to different sites by phagocytosis of apoptotic MSCs, thereby achieving systemic immunosuppression. Accordingly, it was suggested that characterization of the programmed cell death-mediated immunomodulatory signaling pathways in MSCs should be a focus of research.

Heparin Biofunctionalized Selenium Nanoparticles as Potential Antiangiogenic-Chemotherapeutic Agents for Targeted Doxorubicin Delivery

Combining antiangiogenic and chemotherapeutic agents has shown promising clinical benefits in cancer cures when the therapeutic intervention takes into account the tissue and molecular targets. Moreover, the risk of induced drug resistance is minimized when multiple pathways are involved in the treatment regimen, yielding a better therapeutic outcome. Nanodrug delivery systems have proven to be a prudent approach to treating complex disease pathologies. As such, combining antiangiogenic and chemotherapeutic drugs within multimodal nanocarriers synergistically augments the clinical efficiency of the drugs. This study reports the combinatorial efficacy of heparin (Hep), selenium NPs (SeNPs), and doxorubicin (Dox) to inhibit tumor growth and progression. Both Se@Hep-NPs and Se@Hep-Dox-NPs with excellent water dispersity having a size and charge in the range of 250 ± 5 and 253 ± 5 nm and -53 ± 0.4 and -48.4 ± 6.4 mV, respectively, showed strong anticancer potential assessed through in vitro assays like cell viability, specificity, colony formation, and wound scratch in MCF7 cells. Strong synergistic interactions among SeNPs, Hep, and Dox in Se@Hep-Dox-NPs render it to be an antiangiogenic and proapoptotic cancer cell death inducers. In vivo imaging highlights the dual-mode attributes of Se@Hep-NPs with desirable passive tumor targeting and biomedical imaging ability when tagged with Cy7.5, while Se@Hep-Dox-NPs significantly reduce the tumor burden and prolong the longevity of subcutaneous EAC-bearing mice. Histopathology studies reveal no signs of toxicity in major organs. Collectively, these results qualify Se@Hep-Dox-NPs as a plausible clinical therapeutic candidate.

Update of cellular responses to the efferocytosis of necroptosis and pyroptosis

Cell death is a basic physiological process that occurs in all living organisms. A few key players in these mechanisms, as well as various forms of cell death programming, have been identified. Apoptotic cell phagocytosis, also known as apoptotic cell clearance, is a well-established process regulated by a number of molecular components, including 'find-me', 'eat-me' and engulfment signals. Efferocytosis, or the rapid phagocytic clearance of cell death, is a critical mechanism for tissue homeostasis. Despite having similar mechanism to phagocytic clearance of infections, efferocytosis differs from phagocytosis in that it induces a tissue-healing response and is immunologically inert. However, as field of cell death has rapid expanded, much attention has recently been drawn to the efferocytosis of additional necrotic-like cell types, such as necroptosis and pyroptosis. Unlike apoptosis, this method of cell suicide allows the release of immunogenic cellular material and causes inflammation. Regardless of the cause of cell death, the clearance of dead cells is a necessary function to avoid uncontrolled synthesis of pro-inflammatory molecules and inflammatory disorder. We compare and contrast apoptosis, necroptosis and pyroptosis, as well as the various molecular mechanisms of efferocytosis in each type of cell death, and investigate how these may have functional effects on different intracellular organelles and signalling networks. Understanding how efferocytic cells react to necroptotic and pyroptotic cell uptake can help us understand how to modulate these cell death processes for therapeutic purposes.

Caspases help to spread the message via extracellular vesicles

Cell-cell communication is an essential aspect of multicellular life, key for coordinating cell proliferation, growth, and death in response to environmental changes. Whilst caspases are well-known for facilitating apoptotic and pyroptotic cell death, several recent investigations are uncovering new roles for these enzymes in biological scenarios requiring long-range intercellular signalling mediated by extracellular vesicles (EVs). EVs are small membrane-bound nanoparticles released from cells that may carry and deliver cargo between distant cells, thus helping to coordinate their behaviour. Intriguingly, there is emerging evidence indicating a key contribution of caspases in the biogenesis of EVs, the selection of their cargo content, and EV uptake/function in recipient cells. Here, we discuss the latest findings supporting the interplay between caspases and EVs, and the biological relevance of this molecular convergence for cellular signalling, principally in non-apoptotic scenarios.

Ferroptosis in lung cancer: a novel pathway regulating cell death and a promising target for drug therapy

Lung cancer is a common malignant tumor that occurs in the human body and poses a serious threat to human health and quality of life. The existing treatment methods mainly include surgical treatment, chemotherapy, and radiotherapy. However, due to the strong metastatic characteristics of lung cancer and the emergence of related drug resistance and radiation resistance, the overall survival rate of lung cancer patients is not ideal. There is an urgent need to develop new treatment strategies or new effective drugs to treat lung cancer. Ferroptosis, a novel type of programmed cell death, is different from the traditional cell death pathways such as apoptosis, necrosis, pyroptosis and so on. It is caused by the increase of iron-dependent reactive oxygen species due to intracellular iron overload, which leads to the accumulation of lipid peroxides, thus inducing cell membrane oxidative damage, affecting the normal life process of cells, and finally promoting the process of ferroptosis. The regulation of ferroptosis is closely related to the normal physiological process of cells, and it involves iron metabolism, lipid metabolism, and the balance between oxygen-free radical reaction and lipid peroxidation. A large number of studies have confirmed that ferroptosis is a result of the combined action of the cellular oxidation/antioxidant system and cell membrane damage/repair, which has great potential application in tumor therapy. Therefore, this review aims to explore potential therapeutic targets for ferroptosis in lung cancer by clarifying the regulatory pathway of ferroptosis. Based on the study of ferroptosis, the regulation mechanism of ferroptosis in lung cancer was understood and the existing chemical drugs and natural compounds targeting ferroptosis in lung cancer were summarized, with the aim of providing new ideas for the treatment of lung cancer. In addition, it also provides the basis for the discovery and clinical application of chemical drugs and natural compounds targeting ferroptosis to effectively treat lung cancer.

The Applications and Potentials of Extracellular Vesicles from Different Cell Sources in Periodontal Regeneration

Periodontitis is a chronic infectious disease worldwide that can cause damage to periodontal supporting tissues including gingiva, bone, cementum and periodontal ligament (PDL). The principle for the treatment of periodontitis is to control the inflammatory process. Achieving structural and functional regeneration of periodontal tissues is also essential and remains a major challenge. Though many technologies, products, and ingredients were applied in periodontal regeneration, most of the strategies have limited outcomes. Extracellular vesicles (EVs) are membranous particles with a lipid structure secreted by cells, containing a large number of biomolecules for the communication between cells. Numerous studies have demonstrated the beneficial effects of stem cell-derived EVs (SCEVs) and immune cell-derived EVs (ICEVs) on periodontal regeneration, which may be an alternative strategy for cell-based periodontal regeneration. The production of EVs is highly conserved among humans, bacteria and plants. In addition to eukaryocyte-derived EVs (CEVs), a growing body of literature suggests that bacterial/plant-derived EVs (BEVs/PEVs) also play an important role in periodontal homeostasis and regeneration. The purpose of this review is to introduce and summarize the potential therapeutic values of BEVs, CEVs and PEVs in periodontal regeneration, and discuss the current challenges and prospects for EV-based periodontal regeneration.

Determination of Intracellular Esterase Activity Using Ratiometric Raman Sensing and Spectral Phasor Analysis

Carboxylesterases (CEs) are a class of enzymes that catalyze the hydrolysis of esters in a variety of endogenous and exogenous molecules. CEs play an important role in drug metabolism, in the onset and progression of disease, and can be harnessed for prodrug activation strategies. As such, the regulation of CEs is an important clinical and pharmaceutical consideration. Here, we report the first ratiometric sensor for CE activity using Raman spectroscopy based on a bisarylbutadiyne scaffold. The sensor was shown to be highly sensitive and specific for CE detection and had low cellular cytotoxicity. In hepatocyte cells, the ratiometric detection of esterase activity was possible, and the result was validated by multimodal imaging with standard viability stains used for fluorescence microscopy within the same cell population. In addition, we show that the detection of localized ultraviolet damage in a mixed cell population was possible using stimulated Raman scattering microscopy coupled with spectral phasor analysis. This sensor demonstrates the practical advantages of low molecular weight sensors that are detected using ratiometric Raman imaging and will have applications in drug discovery and biomedical research.

New substances of Equisetum hyemale L. extracts and their in vivo antitumoral effect against oral squamous cell carcinoma

ETHNOBOTANICAL RELEVANCE

Equisetum hyemale is used in traditional medicine as an anti-inflammatory, antioxidant, diuretic and anticancer agent. Recent studies have observed antiproliferative activity of this species in some tumor cell lines.

AIM OF THE STUDY

The aim of this study was to evaluate the antiproliferative activity of the ethanol extract of E. hyemale and its partitions in oral squamous carcinoma cell lines, the death pathways induced by the most active partition, the acute toxicity and therapeutic activity, and the identification of the main compounds.

MATERIALS AND METHODS

The ethanol crude extract was prepared from the stems of E. hyemale and partitions were obtained from this extract with n-hexane, dichloromethane and ethyl acetate. Cytotoxicity assays were performed using MTT on human oral tumor lines SCC-9, SCC4 and SCC-25, and normal primary fibroblasts. The main pathways of programmed cell death were analyzed. Acute toxicity in mice was performed using the most active partition, ethyl acetate. Antitumor activity was accessed in xenotransplants grafts of SCC-9 cells in Balb/nude mice. Phytochemical analysis was performed using UHPLC-MS/MS and dereplication was done using Global Natural Product Social Molecular Networking (GNPS) analysis.

RESULTS

Ethanol extract, n-hexane and ethyl acetate partitions showed dose-dependent activity and selectivity towards oral tumor cells, with the ethyl acetate being the most bioactive. This medium polarity partition was shown to induce tumor cell death through apoptosis due to the presence of activated caspase 3/7, DNA fragmentation, chromatin condensation and phosphatidylserine exposure. The ethyl acetate partition also produced low toxicity in mice, provoking mild hepatic changes, but without causing necrosis and significantly reduced tumors volume and weight in xenotransplants of SCC-9 cells. Phytochemical analysis allowed identification of kaempferol glycosides and cinnamic acid derivatives previously described for E. hyemale. In addition it was possible to identify 6 new non-glycolyzed flavonoids 5-Hydroxy-3',4',7,8-tetramethoxyflavone (14), 5,4'-Dihydroxy-7,8,3'-trimethoxyflavone (15), 5,7-Dihydroxy-3',4'-dimethoxyflavone (16), 3',4,5,7-Tretramethoxyflavone (17), 5-Hydroxy-3'4',7-trimethoxyflavone (18), and 5,4'-Dihydroxy-3'-7'-dimethoxyflavone (19); besides 5 compounds already determined to be cytotoxic in other species, Isoferulic acid (1), Ferulic acid (2), Atractylenolide III (6), Dihydroxy-3',4'-dimethoxyflavone (16), and 5-Hydroxy-3'4 ',7-trimethoxyflavone (18).

CONCLUSION

The results indicate that the E. hyemale extract and partitions inhibited 3 different cell lines of OSCC in a highly selective nontoxic way by inducing apoptosis of the cells. We identified 6 new non-glycosylated flavonoids and 5 other substances in this species.

Preclinical to clinical utility of ROCK inhibitors in cancer

ROCK belongs to the AGC family of Ser/Thr protein kinases that are involved in many cellular processes. ROCK-driven actomyosin contractility regulates cytoskeletal dynamics underpinning cell migration, proliferation, and survival in many cancer types. ROCK1/2 play key protumorigenic roles in several subtypes and stages of cancer development. Therefore, successfully targeting ROCK and its downstream effectors presents an interesting avenue for cancer treatment. Because local use of ROCK inhibitors will reduce the side effects of systemic administration, we propose different therapeutic strategies and latest-generation ROCK inhibitors for use in the clinic.

Desmosome-anchored intermediate filaments facilitate tension-sensitive RhoA signaling for epithelial homeostasis

Epithelia are subject to diverse forms of mechanical stress during development and post-embryonic life. They possess multiple mechanisms to preserve tissue integrity against tensile forces, which characteristically involve specialized cell-cell adhesion junctions coupled to the cytoskeleton. Desmosomes connect to intermediate filaments (IF) via desmoplakin (DP)1,2, while the E-cadherin complex links to the actomyosin cytoskeleton in adherens junctions (AJ)3. These distinct adhesion-cytoskeleton systems support different strategies to preserve epithelial integrity, especially against tensile stress. IFs coupled to desmosomes can passively respond to tension by strain-stiffening4-10, whereas for AJs a variety of mechanotransduction mechanisms associated with the E-cadherin apparatus itself11,12, or proximate to the junctions13, can modulate the activity of its associated actomyosin cytoskeleton by cell signaling. We now report a pathway where these systems collaborate for active tension-sensing and epithelial homeostasis. We found that DP was necessary for epithelia to activate RhoA at AJ on tensile stimulation, an effect that required its capacity to couple IF to desmosomes. DP exerted this effect by facilitating the association of Myosin VI with E-cadherin, the mechanosensor for the tension-sensitive RhoA pathway at AJ12. This connection between the DP-IF system and AJ-based tension-sensing promoted epithelial resilience when contractile tension was increased. It further facilitated epithelial homeostasis by allowing apoptotic cells to be eliminated by apical extrusion. Thus, active responses to tensile stress in epithelial monolayers reflect an integrated response of the IF- and actomyosin-based cell-cell adhesion systems.

50 years on and still very much alive: 'Apoptosis: a basic biological phenomenon with wide-ranging implications in tissue kinetics'

Cell death is part of the lifecycle of every multicellular organism. Nineteenth-century pathologists already recognised that organised forms of cell death must exist to explain the demise and turnover of cells during metamorphosis (of insects), embryogenesis and normal tissue homoeostasis [1]. Nevertheless, Kerr, Wyllie and Currie in their seminal paper of 1972, were the first to collate and define the distinct morphological features of controlled cell death in different contexts [2]. To describe the processes of cell deletion observed under both physiological and pathological conditions, they coined the term 'Apoptosis' (derived from the Greek word 'ἀπόπτωσις', meaning 'dropping off or falling off' of petals from flowers). Kerr, Wyllie and Currie defined apoptosis as a mechanism 'complementary to mitosis in the regulation of animal cell populations'. In addition, they already recognised the potential to use this programmed form of cell death for cancer therapy, but they also emphasised the occurrence of apoptosis during cancer development. In this article, some 50 years after its initial publication in The British Journal of Cancer, we revaluate and put the authors initial assumptions and general concepts about apoptosis into the context of modern-day biology.

Mitochondrial-Derived Vesicles-Link to Extracellular Vesicles and Implications in Cardiovascular Disease

Mitochondria are dynamic organelles regulating metabolism, cell death, and energy production. Therefore, maintaining mitochondrial health is critical for cellular homeostasis. Mitophagy and mitochondrial reorganization via fission and fusion are established mechanisms for ensuring mitochondrial quality. In recent years, mitochondrial-derived vesicles (MDVs) have emerged as a novel cellular response. MDVs are shed from the mitochondrial surface and can be directed to lysosomes or peroxisomes for intracellular degradation. MDVs may contribute to cardiovascular disease (CVD) which is characterized by mitochondrial dysfunction. In addition, evidence suggests that mitochondrial content is present in extracellular vesicles (EVs). Herein, we provide an overview of the current knowledge on MDV formation and trafficking. Moreover, we review recent findings linking MDV and EV biogenesis and discuss their role in CVD. Finally, we discuss the role of vesicle-mediated mitochondrial transfer and its potential cardioprotective effects.

Platelet-Derived Extracellular Vesicles in Arterial Thrombosis

Blood platelets are necessary for normal haemostasis but also form life-threatening arterial thrombi when atherosclerotic plaques rupture. Activated platelets release many extracellular vesicles during thrombosis. Phosphatidylserine-exposing microparticles promote coagulation. Small exosomes released during granule secretion deliver cargoes including microRNAs to cells throughout the cardiovascular system. Here, we discuss the mechanisms by which platelets release these extracellular vesicles, together with the possibility of inhibiting this release as an antithrombotic strategy.

Apoptosis regulation by the tyrosine-protein kinase CSK

C-terminal Src kinase (CSK) is a cytosolic tyrosine-protein kinase with an important role in regulating critical cellular decisions, such as cellular apoptosis, survival, proliferation, cytoskeletal organization and many others. Current knowledge on the CSK mechanisms of action, regulation and functions is still at an early stage, most of CSK's known actions and functions being mediated by the negative regulation of the SRC family of tyrosine kinases (SFKs) through phosphorylation. As SFKs play a vital role in apoptosis, cell proliferation and survival regulation, SFK inhibition by CSK has a pro-apoptotic effect, which is mediated by the inhibition of cellular signaling cascades controlled by SFKs, such as the MAPK/ERK, STAT3 and PI3K/AKT signaling pathways. Abnormal functioning of CSK and SFK activation can lead to diseases such as cancer, cardiovascular and neurological manifestations. This review describes apoptosis regulation by CSK, CSK inhibition of the SFKs and further explores the clinical relevance of CSK in important pathologies, such as cancer, autoimmune, autoinflammatory, neurologic diseases, hypertension and HIV/AIDS.

Actin remodeling mediates ROS production and JNK activation to drive apoptosis-induced proliferation

Stress-induced cell death, mainly apoptosis, and its subsequent tissue repair is interlinked although our knowledge of this connection is still very limited. An intriguing finding is apoptosis-induced proliferation (AiP), an evolutionary conserved mechanism employed by apoptotic cells to trigger compensatory proliferation of their neighboring cells. Studies using Drosophila as a model organism have revealed that apoptotic caspases and c-Jun N-terminal kinase (JNK) signaling play critical roles to activate AiP. For example, the initiator caspase Dronc, the caspase-9 ortholog in Drosophila, promotes activation of JNK leading to release of mitogenic signals and AiP. Recent studies further revealed that Dronc relocates to the cell cortex via Myo1D, an unconventional myosin, and stimulates production of reactive oxygen species (ROS) to trigger AiP. During this process, ROS can attract hemocytes, the Drosophila macrophages, which further amplify JNK signaling cell non-autonomously. However, the intrinsic components connecting Dronc, ROS and JNK within the stressed signal-producing cells remain elusive. Here, we identified LIM domain kinase 1 (LIMK1), a kinase promoting cellular F-actin polymerization, as a novel regulator of AiP. F-actin accumulates in a Dronc-dependent manner in response to apoptotic stress. Suppression of F-actin polymerization in stressed cells by knocking down LIMK1 or expressing Cofilin, an inhibitor of F-actin elongation, blocks ROS production and JNK activation, hence AiP. Furthermore, Dronc and LIMK1 genetically interact. Co-expression of Dronc and LIMK1 drives F-actin accumulation, ROS production and JNK activation. Interestingly, these synergistic effects between Dronc and LIMK1 depend on Myo1D. Therefore, F-actin remodeling plays an important role mediating caspase-driven ROS production and JNK activation in the process of AiP.

A Clockwork Bleb: cytoskeleton, calcium, and cytoplasmic fluidity

When the plasma membrane (PM) detaches from the underlying actin cortex, the PM expands according to intracellular pressure and a spherical membrane protrusion called a bleb is formed. This bleb retracts when the actin cortex is reassembled underneath the PM. Whereas this phenomenon seems simple at first glance, there are many interesting, unresolved cell biological questions in each process. For example, what is the membrane source to enlarge the surface area of the PM during rapid bleb expansion? What signals induce actin reassembly for bleb retraction, and how is cytoplasmic fluidity regulated to allow rapid membrane deformation during bleb expansion? Furthermore, emerging evidence indicates that cancer cells use blebs for invasion, but little is known about how molecules that are involved in bleb formation, expansion, and retraction are coordinated for directional amoeboid migration. In this review, we discuss the molecular mechanisms involved in the regulation of blebs, which have been revealed by various experimental systems.

Poly(ε-Caprolactone) Substrates with Micro/Nanohierarchical Patterned Structures for Cell Culture

A simple, efficient and controllable one-step template method is proposed to fabricate poly(ε-caprolactone) substrates with micro/nanohierarchical patterned structures. Two kinds of geometric patterns with and without nanowires, i.e., hexagonal and strip with controllable island size and spacing are designed and fabricated. Furthermore, the influence of geometric patterns, island size, island spacing, and patterned nanowires (pNW) on the growth behavior of MG-63 cells is studied in terms of cell density, distribution, proliferation, morphogenesis, and cellular alignment. It is found that MG-63 cells prefer to adhere and grow on the substrate with smaller island size or spacing. Moreover, unlike the hexagonal structure, the strip structure can guide cellular alignment on its surface. In addition, the microisland structures and the pNW play different roles in promoting cell proliferation, distribution, and morphogenesis. It is concluded that the growth behavior of MG-63 cells can be well controlled by precisely adjusting the micro/nanostructure of the substrate surface. A simple and effective method is provided here for the regulation of cell growth behavior.

Immunogenic Death of Hepatocellular Carcinoma Cells in Mice Expressing Caspase-Resistant ROCK1 Is Not Replicated by ROCK Inhibitors

The morphological changes during apoptosis help facilitate "immunologically silent" cell death. Caspase cleavage of the ROCK1 kinase results in its activation, which drives the forceful contraction of apoptotic cells. We previously showed that when ROCK1 was mutated to render it caspase-resistant, there was greater liver damage and neutrophil recruitment after treatment with the hepatotoxin diethylnitrosamine (DEN). We now show that acute DEN-induced liver damage induced higher levels of pro-inflammatory cytokines/chemokines, indicative of immunogenic cell death (ICD), in mice expressing non-cleavable ROCK1 (ROCK1nc). Hepatocellular carcinoma (HCC) tumours in ROCK1nc mice had more neutrophils and CD8⁺ T cells relative to mice expressing wild-type ROCK1, indicating that spontaneous tumour cell death also was more immunogenic. Since ICD induction has been proposed to be tumour-suppressive, the effects of two distinct ROCK inhibitors on HCC tumours was examined. Both fasudil and AT13148 significantly decreased tumour numbers, areas and volumes, but neither resulted in greater numbers of neutrophils or CD8+ T cells to be recruited. In the context of acute DEN-induced liver damage, AT13148 inhibited the recruitment of dendritic, natural killer and CD8⁺ T cells to livers. These observations indicate that there is an important role for ROCK1 cleavage to limit immunogenic cell death, which was not replicated by systemic ROCK inhibitor administration. As a result, concomitant administration of ROCK inhibitors with cancer therapeutics would be unlikely to result in therapeutic benefit by inducing ICD to increase anti-tumour immune responses.

How Do Extracellular Vesicles Play a Key Role in the Maintenance of Bone Homeostasis and Regeneration? A Comprehensive Review of Literature

The maintenance of bone homeostasis includes both bone resorption by osteoclasts and bone formation by osteoblasts. These two processes are in dynamic balance to maintain a constant amount of bone for accomplishing its critical functions in daily life. Multiple cell type communications are involved in these two complex and continuous processes. In recent decades, an increasing number of studies have shown that osteogenic and osteoclastic extracellular vesicles play crucial roles in regulating bone homeostasis through paracrine, autosecretory and endocrine signaling. Elucidating the functional roles of extracellular vesicles in the maintenance of bone homeostasis may contribute to the design of new strategies for bone regeneration. Hence, we review the recent understandings of the classification, production process, extraction methods, structure, contents, functions and applications of extracellular vesicles in bone homeostasis. We highlight the contents of various bone-derived extracellular vesicles and their interactions with different cells in the bone microenvironment during bone homeostasis. We also summarize the recent advances in EV-loaded biomaterial scaffolds for bone regeneration and repair.

Novel Formulation of Undecylenic Acid induces Tumor Cell Apoptosis

Undecylenic acid, a monounsaturated fatty acid, is currently in clinical use as a topical antifungal agent, however the potential for therapeutic application in other disease settings has not been investigated. In this study, we describe a novel platform for the solubilization of fatty acids using amino acids and utilize this approach to define a tumoricidal activity and underlying mechanism for undecylenic acid. We examined a novel formulation of undecylenic acid compounded with L-Arginine, called GS-1, that induced concentration-dependent tumor cell death, with undecylenic acid being the cytotoxic component. Further investigation revealed that GS-1-mediated cell death was caspase-dependent with a reduction in mitochondrial membrane potential, suggesting a pro-apoptotic mechanism of action. Additionally, GS-1 was found to localize intracellularly to lipid droplets. In contrast to previous studies where lipid droplets have been shown to be protective against fatty acid-induced cell death, we showed that lipid droplets could not protect against GS-1-induced cytotoxicity. We also found a role for Fatty Acid Transport Protein 2 (FATP2) in the uptake of this compound. Collectively, this study demonstrates that GS-1 has effective pro-apoptotic antitumor activity in vitro and, together with the novel platform of fatty acid solubilization, contributes to the re-emerging field of fatty acids as potential anti-cancer therapeutics.

Effect of Rho-Associated Kinase Inhibitor on Growth Behaviors of Human Induced Pluripotent Stem Cells in Suspension Culture

Rho-associated protein kinase (ROCK) inhibitors are used for the survival of single-dissociated human induced pluripotent stem cells (hiPSCs); however, their effects on the growth behaviors of hiPSCs in suspension culture are unexplored. Therefore, we investigated the effect of ROCK inhibitor on growth behaviors of two hiPSC lines (Tic and 1383D2) with different formation of aggregate that attached between single cells in suspension culture. The apparent specific growth rate by long-term exposure to Y-27632, a ROCK inhibitor, was maintained throughout the culture. Long-term exposure to ROCK inhibitor led to an increase in cell division throughout the culture in both lines. Immunofluorescence staining confirmed that hiPSCs forming spherical aggregates showed localization of collagen type I on its periphery. In addition, phosphorylated myosin (pMLC) was localized at the periphery in culture under short-term exposure to ROCK inhibitor, whereas pMLC was not detected at whole the aggregate in culture under long-term exposure. Scanning electron microscopy indicated that long-term exposure to ROCK inhibitor blocked the structural alteration on the surface of cell aggregates. These results indicate that pMLC inhibition by long-term ROCK inhibition leads to enhanced growth abilities of hiPSCs in suspension culture by maintaining the structures of extracellular matrices.

Apoptotic MSCs and MSC-Derived Apoptotic Bodies as New Therapeutic Tools

Over the past two decades, mesenchymal stem cells (MSCs) have shown promising therapeutic effects both in preclinical studies (in animal models of a wide range of diseases) and in clinical trials. However, the efficacy of MSC-based therapy is not always predictable. Moreover, despite the large number of studies, the mechanisms underlying the regenerative potential of MSCs are not fully elucidated. Recently, it has been reliably established that transplanted MSCs can undergo rapid apoptosis and clearance from the recipient's body, still exhibiting therapeutic effects, especially those associated with their immunosuppressive/immunomodulating properties. The mechanisms underlying these effects can be mediated by the efferocytosis of apoptotic MSCs by host phagocytic cells. In this concise review, we briefly describe three types of MSC-generated extracellular vesicles, through which their therapeutic functions can potentially be carried out; we focused on reviewing recent data on apoptotic MSCs and MSC-derived apoptotic bodies (MSC-ApoBDs), their functions, and the mechanisms of their therapeutic effects.

A caspase-RhoGEF axis contributes to the cell size threshold for apoptotic death in developing Caenorhabditis elegans

A cell's size affects the likelihood that it will die. But how is cell size controlled in this context and how does cell size impact commitment to the cell death fate? We present evidence that the caspase CED-3 interacts with the RhoGEF ECT-2 in Caenorhabditis elegans neuroblasts that generate "unwanted" cells. We propose that this interaction promotes polar actomyosin contractility, which leads to unequal neuroblast division and the generation of a daughter cell that is below the critical "lethal" size threshold. Furthermore, we find that hyperactivation of ECT-2 RhoGEF reduces the sizes of unwanted cells. Importantly, this suppresses the "cell death abnormal" phenotype caused by the partial loss of ced-3 caspase and therefore increases the likelihood that unwanted cells die. A putative null mutation of ced-3 caspase, however, is not suppressed, which indicates that cell size affects CED-3 caspase activation and/or activity. Therefore, we have uncovered novel sequential and reciprocal interactions between the apoptosis pathway and cell size that impact a cell's commitment to the cell death fate.

Extracellular Vesicles and Membrane Protrusions in Developmental Signaling

During embryonic development, cells communicate with each other to determine cell fate, guide migration, and shape morphogenesis. While the relevant secreted factors and their downstream target genes have been characterized extensively, how these signals travel between embryonic cells is still emerging. Evidence is accumulating that extracellular vesicles (EVs), which are well defined in cell culture and cancer, offer a crucial means of communication in embryos. Moreover, the release and/or reception of EVs is often facilitated by fine cellular protrusions, which have a history of study in development. However, due in part to the complexities of identifying fragile nanometer-scale extracellular structures within the three-dimensional embryonic environment, the nomenclature of developmental EVs and protrusions can be ambiguous, confounding progress. In this review, we provide a robust guide to categorizing these structures in order to enable comparisons between developmental systems and stages. Then, we discuss existing evidence supporting a role for EVs and fine cellular protrusions throughout development.

The Protective Effect of Simvastatin on the Systolic Function of the Heart in the Model of Acute Ischemia and Reperfusion Is Due to Inhibition of the RhoA Pathway and Independent of Reduction of MMP-2 Activity

The present study investigated whether Rho-associated protein kinase (RhoA/ROCK) signaling pathway inhibitor simvastatin inhibits matrix metalloproteinase 2 (MMP-2) activity in a rat ischemia-reperfusion injury (I/Ri) model by inhibiting the RhoA/ROCK pathway and reducing MMP-2 mRNA levels. Isolated rat hearts were subjected to aerobic perfusion or I/Ri control. The effect of simvastatin was assessed in hearts subjected to I/Ri. We determined cardiac mechanical function, the content of RhoA, phosphorylated myosin light chain subunit 1 (phospho-MYL9), troponin I, MMP-2, and MMP-2 mRNA in the heart homogenates, as well as MMP-2 activity in heart tissue. We showed that treatment with simvastatin caused improvement in the contractile function of the heart subjected to I/Ri which was accompanied by a decrease of MMP-2 activity in heart tissue along with inhibition of RhoA pathway, expressed in a reduction in both RhoA and its downstream product—phosphorylated myosin light chain (phospho-MYL9) in hearts treated with simvastatin. MMP-2 inactivation is not due to inhibition of MMP-2 m-RNA synthesis caused by inhibition of RhoA/ROCK pathway and is due, at least in part, to the direct drug action. The protective effect of simvastatin on systolic function in the acute ischemia-reperfusion model does not appear to be related to reduced MMP-2 activation, but other mechanisms related with the inhibition RhoA/ROCK pathway.

Live-cell imaging in human colonic monolayers reveals ERK waves limit the stem cell compartment to maintain epithelial homeostasis

The establishment and maintenance of different cellular compartments in tissues is a universal requirement across all metazoans. Maintaining the correct ratio of cell types in time and space allows tissues to form patterned compartments and perform complex functions. Patterning is especially evident in the human colon, where tissue homeostasis is maintained by stem cells in crypt structures that balance proliferation and differentiation. Here, we developed a human 2D patient derived organoid screening platform to study tissue patterning and kinase pathway dynamics in single cells. Using this system, we discovered that waves of ERK signaling induced by apoptotic cells play a critical role in maintaining tissue patterning and homeostasis. If ERK is activated acutely across all cells instead of in wave-like patterns, then tissue patterning and stem cells are lost. Conversely, if ERK activity is inhibited, then stem cells become unrestricted and expand dramatically. This work demonstrates that the colonic epithelium requires coordinated ERK signaling dynamics to maintain patterning and tissue homeostasis. Our work reveals how ERK can antagonize stem cells while supporting cell replacement and the function of the gut.

Metabolic alterations and mitochondrial dysfunction underlie hepatocellular carcinoma cell death induced by a glycogen metabolic inhibitor

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths. There is an urgent need for new targets to treat HCC due to limited treatment options and drug resistance. Many cancer cells are known to have high amount of glycogen than their tissue of origin and inhibition of glycogen catabolism induces cancer cell death by apoptosis. To further understand the role of glycogen in HCC and target it for pharmacotherapy, we studied metabolic adaptations and mitochondrial function in HepG2 cells after pharmacological inhibition of glycogen phosphorylase (GP) by CP-91149 (CP). GP inhibition increased the glycogen levels in HepG2 cells without affecting overall glucose uptake. Glycolytic capacity and importantly glycolytic reserve decreased significantly. Electron microscopy revealed that CP treatment altered mitochondrial morphology leading to mitochondrial swelling with less defined cristae. A concomitant decrease in mitochondrial oxygen consumption and mitochondria-linked ATP generation was observed. Metabolomics and enzyme activity / expression studies showed a decrease in the pentose phosphate pathway. In addition, CP treatment decreased the growth of HepG2 3D tumor spheroids in a dose- and time-dependent manner. Taken together, our study provides insights into metabolic alterations and mitochondrial dysfunction accompanying apoptosis in HepG2 cells upon GP inhibition. Our study can aid in the understanding of the mechanism and development of metabolic inhibitors to treat HCC.

Role of Pannexin-1-P2X7R signaling on cell death and pro-inflammatory mediator expression induced by Clostridioides difficile toxins in enteric glia

Clostridioides difficile (C. difficile) produces toxins A (TcdA) and B (TcdB), both associated with intestinal damage and diarrhea. Pannexin-1 (Panx1) channels allows the passage of messenger molecules, such as adenosine triphosphate (ATP), which in turn activate the P2X7 receptors (P2X7R) that regulate inflammation and cell death in inflammatory bowel diseases. The aim of this study was to verify the effect of C. difficile infection (CDI) in the expression of Panx1 and P2X7R in intestinal tissues of mice, as well as their role in cell death and IL-6 expression induced by TcdA and TcdB in enteric glial cells (EGCs). Male C57BL/6 mice (8 weeks of age) were infected with C. difficile VPI10463, and the control group received only vehicle per gavage. After three days post-infection (p.i.), cecum and colon samples were collected to evaluate the expression of Panx1 by immunohistochemistry. In vitro, EGCs (PK060399egfr) were challenged with TcdA or TcdB, in the presence or absence of the Panx1 inhibitor (10Panx trifluoroacetate) or P2X7R antagonist (A438079), and Panx1 and P2X7R expression, caspase-3/7 activity and phosphatidylserine binding to annexin-V, as well as IL-6 expression were assessed. CDI increased the levels of Panx1 in cecum and colon of mice compared to the control group. Panx1 inhibitor decreased caspase-3/7 activity and phosphatidylserine-annexin-V binding, but not IL-6 gene expression in TcdA and TcdB-challenged EGCs. P2X7 receptor antagonist accentually reduced caspase-3/7 activity, phosphatidylserine-annexin-V binding, and IL-6 gene expression in TcdA and TcdB-challenged EGCs. In conclusion, Panx1 is increased during CDI and plays an important role in the effects of C. difficile toxins in EGCs, participating in cell death induced by both toxins by promoting caspase-3/7 activation via P2X7R, which is also involved in IL-6 expression induced by both toxins.

Static and Electromagnetic Fields Differently Affect Proliferation and Cell Death Through Acid Enhancement of ROS Generation in Mesenchymal Stem Cells

Magnetic fields remotely influence cellular homeostasis as a physical agent through the changes in cell physicochemical reactions. Magnetic fields affect cell fate, which may provide an important and interesting challenge in stem cell behaviors. Here, we investigated the effects of the static magnetic field (SMF, 20 mT) and electromagnetic field (EMF, 20 mT-50 Hz) on reactive oxygen species (ROS) production and the acidic pH conditions as stimuli to change cell cycle progression and cell death in mesenchymal stem cells. Results show that SMF, EMF, and their simultaneous (SMF+EMF) administration increase ROS and expression of nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 2 (SOD2), and glutathione-S-transferase (GST) as an antioxidant defense system. Besides, intracellular pH (pHi) decreases in presence of either EMF or SMF+EMF, but not SMF. Decreased ROS content using ascorbic acid in these treatments leads to increased pH compared to the magnetic field treatments alone. Furthermore, each magnetic field has different effects on the cellular process of stem cells, including cell cycle, apoptosis and necrosis. Moreover, treatment by SMF enhances the cell viability after 24 h, while EMF or SMF+EMF decreases it. These observations indicate that fluctuations of ROS generation and acid enhancement during SMF and EMF treatments may reveal their beneficial and adverse effects on the molecular and cellular mechanisms involved in the growth, death, and differentiation of stem cells.

Extracellular Vesicles in Pathogenesis and Treatment of Metabolic Associated Fatty Liver Disease

Metabolic associated fatty liver disease (MAFLD) is the most common chronic liver disease worldwide due to the sedentary and overeating lifestyle. Yet, the pathophysiology of MAFLD is still unclear and no drug has been approved for MAFLD treatment. Extracellular vesicles (EVs) are heterogenous membrane-bound particles released from almost all types of cells. These nano-sized particles mediate intercellular communication through their bioactive cargos including nucleic acids, proteins, and lipids. The EVs modulate metabolic homeostasis via communication between adipose tissue and liver. The dysregulation of lipid metabolism leads to inflammation in liver and the number and compounds of EVs are changed during MAFLD. The injured hepatocytes secrete EVs to induce the migration of bone marrow-derived monocytes and the activation of macrophages in liver. The EVs secreted by different cells regulate the alteration of hepatic stellate cell (HSC) phenotypes and HSC activation gives rise to liver fibrosis. Based on the participation of EVs in MAFLD progression, we discuss the prospects of EVs as a therapeutic target and their application in drug delivery.

The role of extracellular vesicles in animal reproduction and diseases

Extracellular vesicles (EVs) are nanosized membrane-enclosed compartments that serve as messengers in cell-to-cell communication, both in normal physiology and in pathological conditions. EVs can transfer functional proteins and genetic information to alter the phenotype and function of recipient cells, which undergo different changes that positively affect their structural and functional integrity. Biological fluids are enriched with several subpopulations of EVs, including exosomes, microvesicles (MVs), and apoptotic bodies carrying several cargoes, such as lipids, proteins, and nucleic acids. EVs associated with the reproductive system are actively involved in the regulation of different physiological events, including gamete maturation, fertilization, and embryo and fetal development. EVs can influence follicle development, oocyte maturation, embryo production, and endometrial-conceptus communication. EVs loaded with cargoes are used to diagnose various diseases, including pregnancy disorders; however, these are dependent on the type of cell of origin and pathological characteristics. EV-derived microRNAs (miRNAs) and proteins in the placenta regulate inflammatory responses and trophoblast invasion through intercellular delivery in the placental microenvironment. This review presents evidence regarding the types of extracellular vesicles, and general aspects of isolation, purification, and characterization of EVs, particularly from various types of embryos. Further, we discuss EVs as mediators and messengers in reproductive biology, the effects of EVs on placentation and pregnancy disorders, the role of EVs in animal reproduction, in the male reproductive system, and mother and embryo cross-communication. In addition, we emphasize the role of microRNAs in embryo implantation and the role of EVs in reproductive and therapeutic medicine. Finally, we discuss the future perspectives of EVs in reproductive biology.

Comprehensive insight into endothelial progenitor cell-derived extracellular vesicles as a promising candidate for disease treatment

Endothelial progenitor cells (EPCs), which are a type of stem cell, have been found to have strong angiogenic and tissue repair capabilities. Extracellular vesicles (EVs) contain many effective components, such as cellular proteins, microRNAs, messenger RNAs, and long noncoding RNAs, and can be secreted by different cell types. The functions of EVs depend mainly on their parent cells. Many researchers have conducted functional studies of EPC-derived EVs (EPC-EVs) and showed that they exhibit therapeutic effects on many diseases, such as cardiovascular disease, acute kidney injury, acute lung injury, and sepsis. In this review article, we comprehensively summarized the biogenesis and functions of EPCs and EVs and the potent role of EPC-EVs in the treatment of various diseases. Furthermore, the current problems and future prospects have been discussed, and further studies are needed to compare the therapeutic effects of EVs derived from various stem cells, which will contribute to the accelerated translation of these applications in a clinical setting.

A unique form of collective epithelial migration is crucial for tissue fusion in the secondary palate and can overcome loss of epithelial apoptosis

Tissue fusion frequently requires the removal of an epithelium that intervenes distinct primordia to form one continuous structure. In the mammalian secondary palate, a midline epithelial seam (MES) forms between two palatal shelves and must be removed to allow mesenchymal confluence. Abundant apoptosis and cell extrusion support their importance in MES removal. However, genetically disrupting the intrinsic apoptotic regulators BAX and BAK within the MES results in complete loss of cell death and cell extrusion, but successful removal of the MES. Novel static- and live-imaging approaches reveal that the MES is removed through streaming migration of epithelial trails and islands to reach the oral and nasal epithelial surfaces. Epithelial trail cells that express the basal epithelial marker ΔNp63 begin to express periderm markers, suggesting that migration is concomitant with differentiation. Live imaging reveals anisotropic actomyosin contractility within epithelial trails, and genetic ablation of actomyosin contractility results in dispersion of epithelial collectives and failure of normal MES migration. These findings demonstrate redundancy between cellular mechanisms of morphogenesis, and reveal a crucial and unique form of collective epithelial migration during tissue fusion.

Summary: Multiple cellular processes mediate secondary palate fusion, including a unique form of streaming collective epithelial migration driven by pulsatile actomyosin contractility.

Microparticles in Diabetic Kidney Disease

Diabetickidneydisease(DKD)isthemostcommoncauseofrenal failure and a major contributor to the socioeconomic burden in chronic kidney disease (CKD) patients worldwide. The pathogenesis of DKD involves all the structures in the nephron, and it is indicated by proteinuria, hypertension, and progressive decline in renal function, leading tosubstantialmorbidityandmortality. Due to the limitations of currently available standard markers (albuminuria and glomerular filtration rate) in the diagnosis and clinical grading of DKD, it's time to have novel biomarkers for early detection, targeted and effective therapy to prevent the progression. Microparticles (MPs) are extracellular vesicles measuring 0.1 to 1 micron derived by cytoskeletal reorganization in the form of cytoplasmic blebs which alters the phospholipid cytochemistry of the cell membrane. They are shed during cell activation and apoptosis as well as plays an important role in cell-to-cell communication. Over the last few decades, both plasma and urinary MPs have been investigated, validated and the preliminary research looks promising. With alterations in their number and composition documented in clinical situations involving both Type1 and 2 diabetes mellitus, microparticles assay appears to be promising in early diagnosis and prognostication of DKD. WecoverthebasicsofmicroparticlesandtheirinvolvementinDKDinthisreviewarticle.

Microparticles in Autoimmunity: Cause or Consequence of Disease?

Microparticles (MPs) are small (100 nm - 1 um) extracellular vesicles derived from the plasma membrane of dying or activated cells. MPs are important mediators of intercellular communication, transporting proteins, nucleic acids and lipids from the parent cell to other cells. MPs resemble the state of their parent cells and are easily accessible when released into the blood or urine. MPs also play a role in the pathogenesis of different diseases and are considered as potential biomarkers. MP isolation and characterization is technically challenging and results in different studies are contradictory. Therefore, uniform guidelines to isolate and characterize MPs should be developed. Our understanding of MP biology and how MPs play a role in different pathological mechanisms has greatly advanced in recent years. MPs, especially if derived from apoptotic cells, possess strong immunogenic properties due to the presence of modified proteins and nucleic acids. MPs are often found in patients with autoimmune diseases where MPs for example play a role in the break of immunological tolerance and/or induction of inflammatory conditions. In this review, we describe the main techniques to isolate and characterize MPs, define the characteristics of MPs generated during cell death, illustrate different mechanism of intercellular communication via MPs and summarize the role of MPs in pathological mechanisms with a particular focus on autoimmune diseases.

ROCK 1 and 2 affect the spatial architecture of 3D spheroids derived from human corneal stromal fibroblasts in different manners

The objective of the current study was to examine the roles of ROCK1 and 2 on the spatial architecture of human corneal stroma. We examined the effects of a pan-ROCK inhibitor (pan-ROCK-i), ripasudil, and a ROCK2 inhibitor (ROCK2-i), KD025 on the expression of genes that encode for ECM proteins including collagen (COL) 1, 4, 6, and fibronectin (FN), their regulators, a tissue inhibitor of metalloproteinase (TIMP) 1-4, matrix metalloproteinase (MMP) 2, 9 and 14, and ER stress-related factors of two- and three-dimensional (2D and 3D) cultures of human corneal stroma fibroblasts (HCSFs), and the physical properties of 3D HCSF spheroids. A gene expression analysis using ROCK-is indicated that KD025 (ROCK2 selective ROCK inhibitor) induced more significant changes than Rip (ripasudil, pan-ROCK inhibitor), suggesting that ROCK2 might be more extensively involved in the metabolism of ECM proteins and cell architectures of the 2D cultured HCSFs than ROCK1. In terms of the physical properties, size and stiffness of the 3D HCSFs spheroids, Rip caused a significant enlargement and this enhancement was concentration-dependent while KD025 also exerted a similar but less pronounced effect. In contrast, Rip and KD025 modulated physical stiffness differently, in that Rip caused a substantial decrease and KD025 caused an increase. Such diverse effects between Rip and KD025 were also observed for the gene expressions of ECM proteins, their regulators, and ER-stress related factors. The findings presented herein suggest that the ROCK1 and 2 influence the spatial architecture of 3D HCFS spheroids in different manners.

Cell-in-cell structure mediates in-cell killing suppressed by CD44

Penetration of immune cells into tumor cells was believed to be immune-suppressive via cell-in-cell (CIC) mediated death of the internalized immune cells. We unexpectedly found that CIC formation largely led to the death of the host tumor cells, but not the internalized immune cells, manifesting typical features of death executed by NK cells; we named this "in-cell killing" which displays the efficacy superior to the canonical way of "kiss-killing" from outside. By profiling isogenic cells, CD44 on tumor cells was identified as a negative regulator of "in-cell killing" via inhibiting CIC formation. CD44 functions to antagonize NK cell internalization by reducing N-cadherin-mediated intercellular adhesion and by enhancing Rho GTPase-regulated cellular stiffness as well. Remarkably, antibody-mediated blockade of CD44 signaling potentiated the suppressive effects of NK cells on tumor growth associated with increased heterotypic CIC formation. Together, we identified CIC-mediated "in-cell killing" as a promising strategy for cancer immunotherapy.

Impact of Epithelial Cell Shedding on Intestinal Homeostasis

The gut barrier acts as a first line of defense in the body, and plays a vital role in nutrition and immunoregulation. A layer of epithelial cells bound together via intercellular junction proteins maintains intestinal barrier integrity. Based on a tight equilibrium between cell extrusion and cell restitution, the renewal of the epithelium (epithelial turnover) permits the preservation of cell numbers. As the last step within the epithelial turnover, cell shedding occurs due to the pressure of cell division and migration from the base of the crypt. During this process, redistribution of tight junction proteins enables the sealing of the epithelial gap left by the extruded cell, and thereby maintains barrier function. Disturbance in cell shedding can create transient gaps (leaky gut) or cell accumulation in the epithelial layer. In fact, numerous studies have described the association between dysregulated cell shedding and infection, inflammation, and cancer; thus epithelial cell extrusion is considered a key defense mechanism. In the gastrointestinal tract, altered cell shedding has been observed in mouse models of intestinal inflammation and appears as a potential cause of barrier loss in human inflammatory bowel disease (IBD). Despite the relevance of this process, there are many unanswered questions regarding cell shedding. The investigation of those mechanisms controlling cell extrusion in the gut will definitely contribute to our understanding of intestinal homeostasis. In this review, we summarized the current knowledge about intestinal cell shedding under both physiological and pathological circumstances.

Safety assessment of graphene oxide and microcystin-LR complex: a toxicological scenario beyond physical mixture

Background

Nanomaterials have been widely used in electrochemistry, sensors, medicine among others applications, causing its inevitable environmental exposure. A raising question is the “carrier” effect due to unique surface properties of nanomaterials, which may collectively impact the bioavailability, toxicokinetic, distribution and biological effects of classic toxicants. Noteworthy, this aspect of information remains largely unexplored.

Methods

Here, we deliberately selected two entities to mimic this scenario. One is graphene oxide (GO), which is made in ton quantity with huge surface-area that provides hydrophilicity and π–π interaction to certain chemicals of unique structures. The other is Microcystin-LR (MCLR), a representative double-bond rich liver-toxic endotoxin widely distributed in aquatic-system. Firstly, the adsorption of GO and MCLR after meeting under environmental conditions was explored, and then we focused on the toxicological effect and related mechanism of GO-MCLR complex on human skin cutin forming cells (HaCaT cells) and normal liver cells (L02 cells).

Results

Abiotically, our study demonstrated that GO could effectively adsorb MCLR through hydrogen bonding and π–π interaction, the oxidation degree of GO-MCLR decreased significantly and surface defect level raised. Compared to GO or MCLR, GO-MCLR was found to induce more remarkable apoptosis and ferroptosis in both HaCaT and L02 cells. The underlying mechanism was that GO-MCLR induced stronger intracellular reactive oxygen species (ROS) and mtROS generation, followed by Fe²⁺ accumulation, mitochondrial dysfunction and cytoskeletal damage.

Conclusions

These results suggest that the GO-MCLR complex formed by GO adsorption of MCLR may exhibit more toxic effects than the single material, which demonstrates the necessity for assessing nano-toxicant complexity. Our discovery may serve as a new toxicological paradigm in which nanomaterial mediated surface adsorption effects could impact the degree of cytotoxicity and toxicological mechanisms of classic toxins.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00466-x.

Ars moriendi: Proteases as sculptors of cellular suicide

The Ars moriendi, which translates to "The Art of Dying," encompasses two Latin texts that gave advice on how to die well and without fear according to the Christian precepts of the late Middle Ages. Given that ten to hundred billion cells die in our bodies every day, it is obvious that the concept of a well and orderly ("regulated") death is also paramount at the cellular level. In apoptosis, as the most well-studied form of regulated cell death, proteases of the caspase family are the central mediators. However, caspases are not the only proteases that act as sculptors of cellular suicide, and therefore, we here provide an overview of the impact of proteases in apoptosis and other forms of regulated cell death.

Combinatorial Effects of the Natural Products Arctigenin, Chlorogenic Acid, and Cinnamaldehyde Commit Oxidation Assassination on Breast Cancer Cells

Major obstacles in current breast cancer treatment efficacy include the ability of breast cancer cells to develop resistance to chemotherapeutic drugs and the off-target cytotoxicity of these drugs on normal cells, leading to debilitating side effects. One major difference between cancer and normal cells is their metabolism, as cancer cells acquire glycolytic and mitochondrial metabolism alterations throughout tumorigenesis. In this study, we sought to exploit this metabolic difference by investigating alternative breast cancer treatment options based on the application of phytochemicals. Herein, we investigated three phytochemicals, namely cinnamaldehyde (CA), chlorogenic acid (CGA), and arctigenin (Arc), regarding their anti-breast-cancer properties. These phytochemicals were administered alone or in combination to MCF-7, MDA-MB-231, and HCC1419 breast cancer or normal MCF-10A and MCF-12F breast cells. Overall, our results indicated that the combination treatments showed stronger inhibitory effects on breast cancer cells versus single treatments. However, only treatments with CA (35 μM), CGA (250 μg/mL), and the combination of CA + CGA (35 μM + 250 μg/mL) showed no significant cytotoxic effects on normal mammary epithelial cells, suggesting that Arc was the driver of normal cell cytotoxicity in all other treatments. CA + CGA and, to a lesser extent, CGA alone effectively induced breast cancer cell death accompanied by decreases in mitochondrial membrane potential, increased mitochondrial superoxide, reduced mitochondrial and glycolytic ATP production, and led to significant changes in cellular and mitochondrial morphology. Altogether, the combination of CA + CGA was determined as the best anti-breast-cancer treatment strategy due to its strong anti-breast-cancer effects without strong adverse effects on normal mammary epithelial cells. This study provides evidence that targeting the mitochondria may be an effective anticancer treatment, and that using phytochemicals or combinations thereof offers new approaches in treating breast cancer that significantly reduce off-target effects on normal cells.

Extracellular Vesicles—New Players in Cell-To-Cell Communication in Gestational Diabetes Mellitus

Research in extracellular vesicles (EVs) has contributed to a better understanding of physiological and pathophysiological conditions. Biologically active cargo, such as miRNAs and proteins, is critical in many different biological processes. In this context, pregnancy is one of the most complex physiological states, which needs a highly regulated system to ensure the correct nourishment and development of the baby. However, pre-existent maternal conditions and habits can modify the EV-cargo and dysregulate the system leading to pregnancy complications, with gestational diabetes mellitus (GDM) being one of the most reported and influential. Calcification and aging of muscle cells, protein modification in vascular control or variations in the levels of specific miRNAs are some of the changes observed or led by EV populations as adaptation to GDM. Interestingly, insulin sensitivity and glucose tolerance changes are not fully understood to date. Nevertheless, the increasing evidence generated has opened new possibilities in the biomarker discovery field but also in the understanding of cellular mechanisms modified and involved in GDM. This brief review aims to discuss some of the findings in GDM and models used for that purpose and their potential roles in the metabolic alterations during pregnancy, with a focus on insulin sensitivity and glucose tolerance.

Modeling axonal regeneration by changing cytoskeletal dynamics in stem cell-derived motor nerve organoids

Oxidative stress triggers axon degeneration and cell death, leading to the development of neurodegenerative diseases. Spinal motor nerves project very long axons, increasing the burden on axonal transport and metabolism. As such, spinal motor nerves are expected to be susceptible to oxidative stress, but model systems for visualizing and investigating acutely degenerating motor axons are limited. In this study, we establish motor nerve organoids from human pluripotent stem cells (hPSCs) with properties similar to those of neuromesodermal progenitors (NMPs), a population of progenitor cells that comprise the caudal spinal cord. Three-dimensional differentiation of organoids efficiently gave rise to mature motor neurons within 18 days. Adherent organoids showed robust axon fascicles and active growth cones under normal conditions. In addition, more homogenous and efficient generation of motor neurons were achieved when organoids were dissociated into individual cells. Hydrogen peroxide-induced oxidative stress resulted in a broad range of signs of axon degeneration including the disappearance of growth cones and neurites, axon retraction, axon fragmentation and bleb formation, and apoptotic cell death, whose severity can be reliably quantifiable in our culture system. Remarkably, cytoskeletal drugs modulating actin or microtubule turnover differentially facilitated axon dynamics and increased axon regenerative potential. Taken together, our motor nerve organoid model could be potentially useful for drug screens evaluating the rearrangement of cytoskeletons in regenerating motor axons.

Regulating life after death: how mechanical communication mediates the epithelial response to apoptosis

It is increasingly evident that cells in tissues and organs can communicate with one another using mechanical forces. Such mechanical signalling can serve as a basis for the assembly of cellular communities. For this to occur, there must be local instabilities in tissue mechanics that are the source of the signals, and mechanisms for changes in mechanical force to be transmitted and detected within tissues. In this review, we discuss these principles using the example of cell death by apoptosis, when it occurs in epithelia. This elicits the phenomenon of apical extrusion, which can rapidly eliminate apoptotic cells by expelling them from the epithelium. Apoptotic extrusion requires that epithelial cells detect the presence of nearby apoptotic cells, something which can be elicited by the mechanotransduction of tensile instabilities caused by the apoptotic cell. We discuss the central role that adherens junctions can play in the transmission and detection of mechanical signals from apoptotic cells.

Rho Kinases in Embryonic Development and Stem Cell Research

The Rho-associated coiled-coil containing kinases (ROCKs or Rho kinases) belong to the AGC (PKA/PKG/PKC) family of serine/threonine kinases and are major downstream effectors of small GTPase RhoA, a key regulator of actin-cytoskeleton reorganization. The ROCK family contains two members, ROCK1 and ROCK2, which share 65% overall identity and 92% identity in kinase domain. ROCK1 and ROCK2 were assumed to be functionally redundant, based largely on their major common activators, their high degree kinase domain homology, and study results from overexpression with kinase constructs or chemical inhibitors. ROCK signaling research has expanded to all areas of biology and medicine since its discovery in 1996. The rapid advance is befitting ROCK’s versatile functions in modulating various cell behavior, such as contraction, adhesion, migration, proliferation, polarity, cytokinesis, and differentiation. The rapid advance is noticeably driven by an extensive linking with clinical medicine, including cardiovascular abnormalities, aberrant immune responsive, and cancer development and metastasis. The rapid advance during the past decade is further powered by novel biotechnologies including CRISPR-Cas and single cell omics. Current consensus, derived mainly from gene targeting and RNA interference approaches, is that the two ROCK isoforms have overlapping and distinct cellular, physiological and pathophysiology roles. In this review, we present an overview of the milestone discoveries in ROCK research. We then focus on the current understanding of ROCK signaling in embryonic development, current research status using knockout and knockin mouse models, and stem cell research.

Efferocytosis of vascular cells in cardiovascular disease

Cell death and the clearance of apoptotic cells are tightly regulated by various signaling molecules in order to maintain physiological tissue function and homeostasis. The phagocytic removal of apoptotic cells is known as the process of efferocytosis, and abnormal efferocytosis is linked to various health complications and diseases, such as cardiovascular disease, inflammatory diseases, and autoimmune diseases. During efferocytosis, phagocytic cells and/or apoptotic cells release signals, such as "find me" and "eat me" signals, to stimulate the phagocytic engulfment of apoptotic cells. Primary phagocytic cells are macrophages and dendritic cells; however, more recently, other neighboring cell types have also been shown to exhibit phagocytic character, including endothelial cells and fibroblasts, although they are comparatively slower in clearing dead cells. In this review, we focus on macrophage efferocytosis of vascular cells, such as endothelial cells, smooth muscle cells, fibroblasts, and pericytes, and its relation to the progression and development of cardiovascular disease. We also highlight the role of efferocytosis-related molecules and their contribution to the maintenance of vascular homeostasis.