Cell Death & Disease最新文献

Cell death and related signaling pathways are essential during development and in various physiological and pathological conditions. Post-translational modifications such as ubiquitination and phosphorylation play an important role in these signaling pathways. The involvement of kinases - enzymes that catalyze protein phosphorylation - in cell death signaling has been extensively studied. On the other hand, not many studies have been devoted to analyzing the role in cell death of phosphatases, enzymes involved in the removal of phosphorylated residues added to proteins by kinases. Obviously, the two opposite reactions, phosphorylation and dephosphorylation, are equally important in the regulation of protein functions and subsequently in the execution of the cell death program. Here, we have summarized recent work on the involvement of serine-threonine PP2C phosphatases in cell death pathways, senescence and autophagy, focusing in particular on the most studied phosphatase PPM1D (PP2Cδ) as an example of the regulatory role of PP2Cs in cell death. The review should help to draw attention to the importance of PP2C family phosphatases in cell death checkpoints and to discover new targets for drug development.

Aortic dissection (AD) poses a significant threat to cardiovascular health globally, yet its underlying mechanisms remain elusive. Smooth muscle cells death and phenotypic switching are critically important pathological processes in AD. Currently, no pharmacological therapies have proven effective in managing AD. This study aims to elucidate the involvement of ferroptosis in AD progression and explore ferroptosis inhibition as a potential therapeutic approach for AD management. Elevated expression of ferroptosis markers (HMOX1, ACSL4, and 4-HNE) was observed in AD patients and β-Aminopropionitrile (BAPN)-induced mice. In vivo administration of silibinin (SIL) attenuated aortic dilation, inflammation, mitochondrial injury, and ferroptosis. SIL treatment enhanced cell viability and mitochondrial function while reducing reactive oxygen species (ROS) generation and mitigating ferroptosis in primary human aortic smooth muscle cells (HASMCs) induced by RSL3 or IKE. Mechanistically, RNA-sequencing analysis identified dysregulation of iron homeostasis and endoplasmic reticulum stress, which were modulated by SIL. Molecular docking, cellular thermal shift assay, drug affinity responsive target stability, and surface plasmon resonance analysis confirmed HMOX1 as a direct target of SIL, highlighting its role in modulating iron homeostasis. Moreover, NCT-502, a PHGDH inhibitor, reversed the protective effect of SIL in RSL3-induced HASMCs. Conversely, 4-PBA and ZnPP demonstrate a facilitative role. This suggests that SIL plays a crucial role in ferroptosis development by modulating iron homeostasis and endoplasmic reticulum stress-mediated serine biosynthesis, both in vitro and in vivo. Iron homeostasis and endoplasmic reticulum stress of HASMCs drive the development of aortic dissection. These findings unveil a novel role of SIL in mitigating ferroptosis in HASMCs, offering a promising therapeutic avenue for treating AD.

The cyclin D1-Cyclin-Dependent Kinases 4 and 6 (CDK4/6) complex is crucial for the development of melanoma. We previously demonstrated that targeting CDK4/6 using small molecule inhibitors (CDK4/6i) suppresses Braf^V600E melanoma growth in vitro and in vivo through induction of cellular senescence. However, clinical trials investigating CDK4/6i in melanoma have not yielded successful outcomes, underscoring the necessity to enhance the therapeutic efficacy of CDK4/6i. Accumulated research has shown that while senescence initially suppresses cell proliferation, a prolonged state of senescence eventually leads to tumor relapse by altering the tumor microenvironment, suggesting that removal of those senescent cells (in a process referred to as senolysis) is of clinical necessity to facilitate clinical response. We demonstrate that glutaminase 1 (GLS1) expression is specifically upregulated in CDK4/6i-induced senescent Braf^V600E melanoma cells. Upregulated GLS1 expression renders Braf^V600E melanoma senescent cells vulnerable to GLS1 inhibitor (GLS1i). Furthermore, we demonstrate that this senolytic approach targeting upregulated GLS1 expression is applicable even though those cells developed resistance to the Braf^V600E inhibitor vemurafenib, a frequently encountered substantial clinical challenge to treating patients. Thus, this novel senolytic approach may revolutionize current CDK4/6i mediated melanoma treatment if melanoma cells undergo senescence prior to developing resistance to CDK4/6i. Given that we demonstrate that a low dose of vemurafenib induced senescence, which renders Braf^V600E melanoma cells susceptible to GLS1i and recent accumulated research shows many cancer cells undergo senescence in response to chemotherapy, radiation, and immunotherapy, this senolytic therapy approach may prove applicable to a wide range of cancer types once senescence and GLS1 expression are induced.

Poly (ADP-ribose) polymerase 1 (PARP1) catalyzes poly (ADP) ribosylation reaction, one of the essential post-translational modifications of proteins in eukaryotic cells. Given that PARP1 inhibition can lead to synthetic lethality in cells with compromised homologous recombination, this enzyme has been identified as a potent target for anti-cancer therapeutics. However, the clinical application of existing PARP1 inhibitors is restrained by side effects associated with DNA trapping and off-target effects, highlighting the need for improved therapeutic strategies. By integrating protein degradation technology, we synthesized a PROTAC molecule 180055 based on the Rucaparib junction and VHL ligand, which efficiently and selectively degraded PARP1 and inhibited PARP1 enzyme activity without a noticeable DNA trapping effect. Furthermore, 180055 kills tumor cells carrying BRCA mutations with a minor impact on the growth of normal cells both in vitro and in vivo. This suggests that 180055 is a PARP1-degrading compound with excellent pharmacological efficacy and extremely high biological safety that deserves further exploration and validation in clinical trials.

Intestinal cell death is a defining feature of Crohn's disease (CD), a major form of inflammatory bowel disease. The focus on this aspect of enteric inflammation has mainly been on epithelial cells, while other cell types such as stromal and myeloid cells have received less attention. Hypothesising that decreased macrophage viability in an oxidative environment could be a contributing factor to the pathophysiology of CD, we found that monocyte-derived macrophages from individuals with active CD (but not those in clinical disease remission) have increased sensitivity to cell death induced by H₂O₂. Molecular biology and pharmacological studies ruled out apoptosis and necroptosis, while increased lipid peroxidation and surface expression of the transferrin receptor implicated ferroptosis as the mechanism of the H₂O₂-induced cell death: this was supported by suppression of H₂O₂-cytotoxicity by liproxstatin-1, a pharmacological inhibitor of ferroptosis. Selenoproteins are important antioxidants, and selenium deficiency can be a feature of CD. Despite normal dietary intake of selenium, monocyte-derived macrophages and intestinal macrophages in individuals with CD had decreased protein and/or mRNA expression of the selenoprotein, glutathione peroxidase (GPx)-1. Knockdown of GPx1 in macrophages from healthy volunteers resulted in increased H₂O₂-induced cell death reminiscent of that observed with macrophages from CD. In summary, monocyte-derived macrophages from individuals with CD have increased susceptibility to H₂O₂-induced ferroptosis cell death, that may be facilitated, at least in part, by reduced expression of the antioxidant GPx1. We suggest that reduced GPx1 in monocytes recruited to the gut and intestinal macrophages renders these cells vulnerable to reactive oxygen species-evoked ferroptosis cell death and that unraveling the participation of this pathway in Crohn's disease may reveal novel therapeutic approaches to this chronic condition.

Regeneration of injured central nervous system (CNS) axons is highly restricted, leading to permanent neurological deficits. The myristoylated alanine-rich C-kinase substrate (MARCKS) is a membrane-associated protein kinase C (PKC) substrate ubiquitously expressed in eukaryotic cells, plays critical roles in development, brain plasticity, and tissues regeneration. However, little is known about the role of Marcks in CNS axon regeneration. Here we show that Marcks overexpression promotes robust axon regeneration either before or after optic nerve crush, but insignificantly impacts neuronal survival. Notably, immunostaining and RNA sequencing demonstrate that Marcks overexpression does not affect known regeneration-associated genes and pathways. Furthermore, combining CNTF which activates the JAK-STAT3 pathway and Marcks overexpression further enhances axon regeneration. Finally, we demonstrate functionally essential effector domain (ED) of MARCKS has similar effects on inducing axon regeneration in RGCs. These results suggest that manipulating Marcks and its ED may become a therapeutic approach to promote axon regeneration after CNS injury.

Little attention was given to heparanase 2 (Hpa2) over the last two decades, possibly because it lacks a heparan sulfate (HS)-degrading activity typical of heparanase. Emerging results suggest, nonetheless, that Hpa2 plays a role in human pathologies, including cancer progression where it functions as a tumor suppressor. Here, we examined the role of Hpa2 in cervical carcinoma. We report that high levels of Hpa2 correlate with prolonged survival of cervical carcinoma patients. Strong staining intensity of Hpa2 also correlates with low tumor grade. Overexpression of Hpa2 in SiHa cervical carcinoma cells resulted in tumor xenografts that were two-fold smaller than control tumors. Interestingly, even smaller tumor xenografts were developed by SiHa cells overexpressing the Pro140Arg and Asn543Ile Hpa2 missense mutations that were identified in patients diagnosed with urofacial syndrome (UFS). Utilizing the Ras recruitment system, we identified bromodomain-containing protein 7 (BRD7) to interact with Hpa2 and found that both BRD7 and the Hpa2 mutants are translocated to the cell nucleus in tumors developed by the Pro140Arg and Asn543Ile Hpa2 mutants. Utilizing our newly developed conditional Hpa2-KO mice, we further show that Hpa2 plays a critical role in macrophage polarization; in the absence of Hpa2, macrophages are shifted towards pro-tumorigenic, M2 phenotype. Notably, implanting SiHa cervical carcinoma cells together with Hpa2-KO macrophages promoted tumor growth. These results support, and further expand, the notion that Hpa2 functions as a tumor suppressor, co-operating with another tumor suppressor, BRD7.

Acute kidney injury (AKI) caused by nephrotoxins, ischemia reperfusion (IR) or sepsis is associated with high morbidity and mortality. Unveiling new mechanisms underlying AKI can help develop new therapeutic strategy. Cullin 4B (CUL4B) is a scaffold protein in the CUL4B-RING E3 ubiquitin ligase (CRL4B) complex. Here, we demonstrate that CUL4B can protect kidneys from acute injury induced by cisplatin and IR. CUL4B is upregulated in mouse tubular epithelial cells (TECs) after cisplatin treatment or IR. Loss of CUL4B in kidneys exacerbates renal injury, inflammation, and apoptosis of TECs caused by cisplatin and IR. Transcriptome analysis reveals that Cul4b deficiency enhances injury-induced PAI-1 expression. CUL4B suppresses PAI-1 expression by promoting polyubiquitination and degradation of p53. Inhibition of either PAI-1 or p53 can prevent the aggravated renal injury and inflammation caused by loss of CUL4B. Our work has identified the kidney-protective role of CUL4B against acute injury.

Sickle cell disease (SCD) is a severe hematological disorder characterized by erythrocyte sickling that causes significant morbidity and mortality. Skeletal complications of SCD include a high incidence of bone loss, especially in vertebrae, leading to fragility fractures that contribute to disease burden. Whether hydroxyurea (HU), a front-line therapy for SCD ameliorates bone disease has not been established. To investigate HU action on SCD-related vertebral defects, we used HU-treated "Townes" mice, an SCD animal model and performed high-resolution micro-computed tomography (µCT) imaging to resolve bone volume and micro-architectural structure of cortical and trabecular bone, the two major compartments contributing to bone mass and strength. Our data revealed that cortical bone was significantly diminished in the vertebrae of skeletally mature (representing adults) and immature (representing children) SCD mice, while only mature mice lost trabecular bone mass. Administration of HU ameliorated cortical bone loss in mature SCD mice, but paradoxically promoted trabecular bone decline in both groups. We further investigated the mechanisms of HU action in wild-type C57BL6/J mice. HU caused dose-dependent trabecular bone loss due to diminished osteoclast and osteoblast function, indicative of a low bone turnover state. Mechanistic investigations in vitro revealed that HU impeded osteoblast-progenitor proliferation and early differentiation, and diminished osteoclastogenic cytokine production, blunting osteoclast formation as well as the activity of mature osteoclasts. HU further, suppressed mitochondrial, but not glycolytic energy metabolism in both differentiating osteoblasts and differentiated osteoclasts. Collectively, these findings reveal that despite ameliorating cortical bone loss, HU inhibits trabecular bone formation and resorption, by suppressing mitochondrial energy metabolism and blunting the differentiation and/or activity of osteoblasts and osteoclasts. Together HU drives a low bone turnover state culminating in trabecular bone loss. Further investigation into HU's impact on bone in SCD patients is warranted for understanding and managing skeletal complications in this population.