Cell Death and Differentiation最新文献

The plasma concentrations of acyl CoA binding protein (ACBP) encoded by the gene diazepam binding inhibitor (DBI) are increased in patients with severe osteoarthritis (OA). Here, we show that knee OA induces a surge in plasma ACBP/DBI in mice subjected to surgical destabilization of one hind limb. Knockout of the Dbi gene or intraperitoneal (i.p.) injection of a monoclonal antibody (mAb) neutralizing ACBP/DBI attenuates OA progression in this model, supporting a pathogenic role for ACBP/DBI in OA. Furthermore, anti-ACBP/DBI mAb was also effective against OA after its intraarticular (i.a.) injection, as monitored by sonography, revealing the capacity of ACBP/DBI to locally reduce knee inflammation over time. In addition, i.a. anti-ACBP/DBI mAb improved functional outcomes, as indicated by the reduced weight imbalance caused by OA. At the anatomopathological level, i.a. anti-ACBP/DBI mAb mitigated histological signs of joint destruction and synovial inflammation. Of note, i.a. anti-ACBP/DBI mAb blunted the OA-induced surge of plasma ACBP/DBI, as well as that of other inflammatory factors including interleukin-1α, interleukin-33, and tumor necrosis factor. These findings are potentially translatable to OA patients because joints from OA patients express both ACBP/DBI and its receptor GABA_ARγ2. Moreover, a novel mAb against ACBP/DBI recognizing an epitope conserved between human and mouse ACBP/DBI demonstrated similar efficacy in mitigating OA as an anti-mouse ACBP/DBI-only mAb. In conclusion, ACBP/DBI might constitute a promising therapeutic target for the treatment of OA.

Impaired glucose uptake regulated by suppressed insulin receptor signaling is a key driving force of podocytopathies. The identification of potential therapeutic targets that mediate podocyte insulin receptor signaling holds significant clinical importance. Here, we observed a substantial reduction in PR domain-containing 16 (PRDM16) expression within damaged podocytes in both humans and mice. Podocyte-specific Prdm16 deletion aggravated podocyte injury, albuminuria, and glomerulosclerosis in diabetic nephropathy (DN) mice. Conversely, exogenous PRDM16 delivered by lentivirus mitigated these pathological changes in DN mice and adriamycin (ADR) nephropathy mice. Furthermore, we demonstrated that loss of PRDM16 blocked glucose uptake of podocytes by inhibiting insulin receptor signaling. Mechanistically, PRDM16 deficiency downregulated the transcription of NEDD4L, subsequently enhancing the stability of IKKβ protein. The accumulation of IKKβ caused by the loss of PRDM16 led to the phosphorylation of serine residues on insulin receptor substrate-1 (IRS-1), thereby promoting IRS-1 degradation. Exogenous NEDD4L mitigated podocyte injury induced by PRDM16 knockdown in vitro and attenuated ADR nephropathy in vivo. Our study clarified the role and mechanism of PRDM16 in insulin receptor signaling and podocyte injury, providing a potential therapeutic target for podocytopathies.

Efferocytosis is crucial for the clearance of apoptotic cells (ACs) following acute ischemic stroke (AIS), however, its mechanism remains unclear. This study reveals that chemokine-like factor 1 (CKLF1) disrupts efferocytosis by promoting AC finding and internalization while impairing AC degradation in microglia. CKLF1 deficiency reduced the proportion of ACs and lowered levels of damage-associated molecular patterns. Mechanistically, CKLF1 binds to phosphatidylserine on apoptotic neurons/blebs, recruiting microglia to the ischemic penumbra via a C-C chemokine receptor 4 (CCR4)-dependent pathway. Apoptotic blebs with CKLF1 are engulfed into microglia, triggering the rapid production of interleukin-6 (IL6). IL6 enhances AC internalization through the signal transducer and activator of transcription 3 (STAT3)-vav guanine nucleotide exchange factor 1 (VAV1)-ras-related C3 botulinum toxin substrate 1 (RAC1) signaling cascade but simultaneously inhibits transcription factor EB (TFEB) nuclear translocation, leading to lysosomal dysfunction. This effect results in AC accumulation, compromising microglial efferocytosis efficiency and integrity. These findings uncover a novel regulatory axis induced by CKLF1, emphasizing the complex balance between AC internalization and degradation in microglial efferocytosis.

Pancreatic ductal adenocarcinoma is characterized by a three-dimensional (3D) tumor microenvironment devoid of oxygen and nutrients but enriched in extracellular matrix, which acts as a physical and chemical barrier. In 3D, cancer cells reprogram their metabolic pathways in ways that help them survive hostile conditions. However, little is known about the metabolic phenotypes of cancer cells in 3D and the intrinsic cues that modulate them. We found that Cxcl5 deletion restricted pancreatic tumor growth in a 3D spheroid-in-Matrigel culture system without affecting cancer cell growth in 2D culture. Cxcl5 deletion impaired 3D-specific global metabolic reprogramming, resistance to hypoxia-induced cell death, and upregulation of Hif1α and Myc. Overexpression of Hif1α and Myc, however, effectively restored 3D culture-induced metabolic reconfiguration, growth, redox homeostasis, and mitochondrial function in Cxcl5^−/− cells, reducing ferroptosis. We also found that pancreatic cancer patients with higher expression of hypoxia and metabolism-related genes whose expression is well-correlated with CXCL5 generally have poorer prognosis. Together, our findings identify an unanticipated role of Cxcl5 in orchestrating the cancer metabolic reprogramming in 3D culture that is required for energy and biomass maintenance and that restricts oxidative cell death. Thus, our results provide a rationale for targeting CXCL5 as a promising therapeutic strategy.

The colonic crypts are principally composed by Lgr5⁺ stem cells and deep crypt secretory (DCS) cells. c-Kit-expressing cells mark DCS cells and supply Wnt3, EGF, and Notch signals to support their neighboring crypt bottom-intermingled Lgr5⁺ cells. However, the role of c-Kit⁺ cells beyond supporting Lgr5⁺ cells in colonic epithelium remains unexplored. Here, we identify that c-Kit⁺ cells are a heterogeneous entity and possess stemness potency to differentiate into the entire spectrum of epithelial cells and renew the homeostatic colon. Intriguingly, c-Kit⁺ cells play a pivotal role in epithelium repair in mouse models of colitis when contemporary Lgr5⁺ cells are insufficient or absent. Depletion of c-Kit⁺ cells or inhibition of SCF/c-Kit signaling worsens, while supplementation of SCF alleviates colonic epithelium injury during colitis. Our findings unravel the fate and function of c-Kit⁺ cells in homeostatic colon and recovery during colonic epithelium injury which has translational implications for human inflammatory bowel diseases.

The ubiquitination of histone H2A/H2AX, catalyzed by RNF8/RNF168, is a crucial step in the repair of DNA double-strand breaks (DSBs), playing a significant role in transmitting and amplifying DNA damage response signals. However, the upstream regulatory mechanisms of RNF168 remain unclear. Here, we demonstrate that ZNF451 catalyzes the SUMOylation of RNF168, thereby regulating the ubiquitination of histone H2A/H2AX. Specifically, ZNF451 rapidly responds to radiation-induced DNA damage, accumulating abundantly at damage sites and catalyzing the SUMO2 modification of RNF168. This modification stabilizes RNF168, enhancing its accumulation at damage sites, which increases the ubiquitination levels of downstream histone H2A/H2AX and promotes the DNA damage repair process. Furthermore, we find that ZNF451 and RNF8 jointly regulate RNF168 in a novel manner, exhibiting both competitive and cooperative characteristics. The interaction between RNF168 and either ZNF451 or RNF8 mutually inhibits each other. However, simultaneous loss of ZNF451 and RNF8 markedly impedes the recruitment of RNF168 to damage sites. Whereas, varying expression levels of ZNF451 and RNF8 suggest that both facilitate the interaction between RNF168 and the downstream factor H2AX, but the interaction plateaus beyond a specific threshold. Altogether, these findings reveal that the SUMOylation catalyzed by ZNF451 is involved in regulating RNF168-induced ubiquitin signaling in DSBs repair and suggest that ZNF451 could serve as a potential therapeutic target in tumor radiotherapy.

Cells produce metabolic intermediates through catalytic reactions, mainly via post-translational modifications. The modification of proteins by O-linked N-acetylglucosamine, known as O-GlcNAcylation, is one of the most common post-translational modifications. As O-GlcNAcylation and phosphorylation can occur at serine or threonine residues, it is crucial that the interplay between these two modifications is vital to bioenergetic and biosynthetic demand. Although emerging recognition linking O-GlcNAc modification and phosphorylation to protein functions has been obtained, the issue of how altered O-GlcNAcylation or phosphorylation regulates each other in the metabolic system remains uncertain. The combination of cell biological and proteomic approaches over the recent few years has not only highlighted the interactions between O-GlcNAcylation and phosphorylation in protein function but also prompted us to elucidate the underlying mechanisms behind this crosstalk controlling metabolic homeostasis. The purpose of this review is to summarize recent advances in the O-GlcNAcylation/phosphorylation regulation of the metabolic process. An extensive exploration of this interplay has significant implications for metabolic control systems, including glucose, lipid, and nucleotide metabolism, where dysregulation in O-GlcNAcylation and phosphorylation of metabolic syndrome is essential.

Hippocampal neurogenesis, the generation of new neurons in the dentate gyrus (DG) of mammalian hippocampus, is essential for cognitive and emotional processes. Despite advances in understanding the transcription factors and signaling pathways that regulate DG neurogenesis, the epigenetic mechanisms underlying the molecular changes necessary for granule neuron generation remain poorly understood. In this study, we investigate the role of the H3K9 demethylase KDM3A in postnatal neurogenesis in mouse DG. Using Kdm3a-tdTomato reporter mice, we demonstrate that KDM3A is predominantly expressed in neural stem/progenitor cells (NSPCs) during postnatal DG development. Conventional or conditional knockout (cKO) of Kdm3a in NSPCs hinders postnatal neurogenesis, compromising learning and memory abilities and impairing brain injury repair in mice. Loss of KDM3A in NSPCs suppresses proliferation and neuronal differentiation while promoting glial differentiation in vitro. KDM3A localizes both in the nucleus and cytoplasm of NSPCs and regulates the Wnt/β-catenin signaling pathway through dual mechanisms. Firstly, KDM3A modulates the transcription of Wnt targets and a set of neurogenesis-related genes through its histone demethylase activity. Secondly, in the cytoplasm, KDM3A interacts with casein kinase I alpha (CK1α), regulating its ubiquitination. Loss of KDM3A enhances CK1α stability, leading to increased phosphorylation and degradation of β-catenin. Finally, quercetin, a geroprotective small molecule, upregulates KDM3A protein expression and promotes adult hippocampal neurogenesis following brain injury. However, these effects are diminished in Kdm3a KO mice, indicating that quercetin primarily promotes hippocampal neurogenesis through the regulation of KDM3A. In conclusion, our study highlights KDM3A as a crucial regulator of postnatal hippocampal neurogenesis, influencing NSPC proliferation and differentiation via the Wnt/β-catenin signaling pathway. These findings have potential implications for the development of new therapeutic approaches for neurological disorders and injuries.

Excessive inflammation and cytokine release are hallmarks of severe COVID-19. Certain programmed cell death processes can drive inflammation, however, their role in the pathogenesis of severe COVID-19 is unclear. Pyroptosis is a pro-inflammatory form of regulated cell death initiated by inflammasomes and executed by the pore-forming protein gasdermin D (GSDMD). Using an established mouse adapted SARS-CoV-2 virus and a panel of gene-targeted mice we found that deletion of the inflammasome (NLRP1/3 and the adaptor ASC) and pore forming proteins involved in pyroptosis (GSDMA/C/D/E) only marginally reduced IL-1β levels and did not impact disease outcome or viral loads. Furthermore, we found that SARS-CoV-2 infection did not trigger GSDMD activation in mouse lungs. Finally, we did not observe any difference between WT animals and mice with compound deficiencies in the pro-inflammatory initiator caspases (C1/11/12^−/−). This indicates that the classical canonical and non-canonical pro-inflammatory caspases known to process and activate pro-IL-1β, pro-IL-18 and GSDMD do not substantially contribute to SARS-CoV-2 pathogenesis. However, the loss of IL-1β, but not the absence of IL-18, ameliorated disease and enhanced survival in SARS-CoV-2 infected animals compared to wildtype mice. Collectively, these findings demonstrate that IL-1β is an important factor contributing to severe SARS-CoV-2 disease, but its release was largely independent of inflammasome and pyroptotic pathways.