Cell Death Discovery最新文献

Retinal ganglion cell (RGC) death is a critical component of glaucoma pathology. The degenerative signaling pathways that lead to RGC death in glaucoma are incompletely defined. Recently, the transcription factors JUN and DDIT3 were identified as critical hubs regulating RGC somal loss after mechanical axonal injury. However, their position within the degenerative cascade remains unclear. One possibility is that JUN and DDIT3 activity in the soma initiates signaling events that trigger axonal degeneration. Alternatively, JUN and DDIT3 may function downstream of the primary insult, acting specifically to mediate somal degeneration without influencing axonal pathology. Disentangling these possibilities is critical for understanding the compartment-specific mechanisms of RGC degeneration in glaucoma. The MAP2Ks MKK4 and MKK7 control JNK and JUN activity and can indirectly activate DDIT3. Furthermore, MKK4 and MKK7 have been shown to drive RGC axonal degeneration after mechanical axonal injury. The present work investigated whether JUN and DDIT3, or their upstream activators MKK4 and MKK7, control degeneration of RGC axons and somas after glaucoma-relevant injuries; including ocular hypertension in aged DBA/2J mice and after mechanical axonal injury (controlled optic nerve crush, CONC) in C57BL/6J mice. Ddit3 and Jun deletion did not prevent RGC axonal degeneration in DBA/2J mice but prevented nearly all somal loss. Despite robust somal survival, Ddit3 and Jun deletion did not prevent RGC somal shrinkage or pattern electroretinography (PERG) amplitude decline in DBA/2J mice or after CONC in C57BL/6J mice. In contrast, Mkk4 and Mkk7 deletion from C57BL/6J mice significantly lessened RGC soma and axon degeneration while preserving PERG amplitude and soma size after CONC. In summary, activation of MKK4 and MKK7 may be an inciting mechanism governing RGC somal and axonal degeneration after glaucoma-relevant axonal injury.

Transforming growth factor-beta (TGFβ) is a major immunosuppressive cytokine produced by various cell types, including regulatory T cells (Tregs) and M2 macrophages. In Tregs, GRP94 is known as a key protein regulating TGFβ expression by chaperoning both the TGFβ docking receptor, GARP, and the integrin αvβ8. We previously reported that GRP94 inhibition in a triple-negative breast cancer (TNBC) murine model induced a decrease in intra-tumoral CD206 + M2-like macrophages that correlated with a decrease in collagen content, an increase in CD8+ cells in tumors and a reduced tumor volume. Here, we investigated the impact of GRP94 inhibition on TGFβ expression focusing on a possible interaction with furin, a proprotein convertase responsible for the first step in TGFβ maturation. We demonstrated in human primary M2 macrophages that GRP94 interacted with furin and that GRP94 inhibition by its selective inhibitor PU-WS13 led to a decrease in furin enzymatic activity, which was associated with a decrease in TGFβ secretion. Similar results were obtained in the human TNBC cell line MDA-MB-231 using PU-WS13 and GRP94 inhibitor- 1, suggesting that our findings are not cell type-specific. Finally, we showed that GRP94 associated with LRRC33, a GARP paralog in macrophages. Together, these findings support the hypothesis that GRP94 plays a key role in regulating the TGFβ maturation pathway, not only in Tregs as previously reported, but also in M2 macrophages and tumor cells.

Retinitis Pigmentosa (RP) is an inherited neurodegenerative disease which leads to loss of retinal photoreceptors and blindness. Histone deacetylases (HDAC) were previously found to be involved in photoreceptor cell death, and HDAC inhibitors have shown protective effects in animal models for autosomal recessive RP. However, whether HDAC inhibitors can protect photoreceptors in autosomal dominant RP (ADRP) remains unclear. Here, we utilized the recently generated human homologous Rho^I255d/+ ADRP mouse model to investigate degenerative mechanisms and the therapeutic potential of HDAC inhibitors. To visualize photoreceptor HDAC activity, we applied an in situ HDAC activity assay on post-natal (P) day 20 wild type (WT) and Rho^I255d/+ retina. Treatment with the HDAC class I/II inhibitor Trichostatin A and the HDAC class III inhibitor nicotinamide (NAM) suggested that most HDAC activity detected in Rho^I255d/+ photoreceptors was related to class I/II isoforms. The therapeutic potential of different HDAC inhibitors, targeting different HDAC isoforms, was evaluated in vitro, on organotypic retinal explants cultured under completely controlled conditions. HDAC inhibitors tested included SAHA (Vorinostat), MPT0G211, ACY-957, and NAM. Readouts comprised the TUNEL assay, immunostaining for activated calpain-2 and caspase-3, cone arrestin-3, and bromodeoxyuridine (BrdU)-labeling. Among the compounds tested, MPT0G211, targeting predominantly cytoplasmic HDAC-6, exhibited the strongest protective effect on both rod and cone photoreceptors. Remarkably, high-dose ACY-957, inhibiting nuclear HDAC-1/-2, induced both photoreceptor cell death and cell proliferation. High levels of NAM, blocking mitochondrial and nuclear HDACs, caused selective rod cell death, without affecting cones. All HDAC inhibitors tested had no or only minor effects on neurons of the inner retina. Our study highlights the complexity and ambiguity of HDAC activity during photoreceptor neurodegeneration and cautions against the use of unspecific inhibitors. At the same time, it showcases important differences between rod and cone photoreceptors and suggests especially HDAC-6 as a potential target for future therapy development.

Glutamine: fructose-6-phosphate amidotransferase (GFAT), a conserved enzyme across prokaryotic and eukaryotic species, is the first and rate-limiting step in the hexosamine biosynthetic pathway (HBP), diverting 2-5% of fructose-6-phosphate derived from glucose toward the synthesis of uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), a key substrate for the glycosylation of proteins and lipids. While substantial progress has been made in elucidating the basic biochemical properties and regulatory mechanisms of GFAT, its functional impact on pathological processes remains incompletely understood. Emerging evidence implicates GFAT in a spectrum of human diseases, including cancer, diabetes, cardiovascular disorders, and neurodegenerative conditions such as Alzheimer's disease. This review aims to provide a comprehensive synthesis of current insights into GFAT's role in disease etiology, with the goal of informing future research and therapeutic strategies targeting this essential metabolic regulator.

Cervical cancer (CC) ranks as the fourth most prevalent malignancy and the second leading cause of cancer-related mortality in women. Central to its pathology are long non-coding RNAs (LncRNAs), a class of transcripts exceeding 200 nucleotides that do not encode proteins. Instead, they function as critical regulators of gene transcription, chromatin remodeling, and cell cycle progression by interacting with DNA, RNA, or proteins, thereby influencing a range of physiological and pathological processes. As research on LncRNA function deepens, its critical role in tumor biology has become increasingly apparent. LncRNAs have attracted considerable attention in recent years regarding their role in the development and progression of CC. LncRNAs are involved in the proliferation, migration, and invasion of CC cells, and also regulate multiple signaling pathways by interacting with other molecules to influence tumor progression. Although several LncRNAs have been identified as biomarkers of CC, and research on their potential as therapeutic targets is advancing, their specific mechanisms of action and clinical application remain poorly understood. This review aims to comprehensively analyze the biological functions and mechanisms of LncRNAs in CC and explore their clinical application potential, providing new insights and directions for the early diagnosis and treatment of CC.

Caspase 6 is a pivotal executioner caspase involved in cell death; however, its role in inflammatory bowel disease (IBD) remains incompletely understood. Levels of cleaved caspase 6 were quantified in colonic tissues from IBD patients, and an IBD mouse model was established via DSS induction, incorporating both systemic (Casp6 KO) and IEC-specific knockout (Casp6 cKO) strategies. Single-cell RNA sequencing (scRNA-seq) revealed that Casp6 KO enhanced necroptosis in IECs, reducing intestinal endocrine cells and damaging intestinal stem cells. Both in vivo and in vitro studies confirmed that caspase 6 deficiency activates the necroptosis pathway by upregulating RIPK1 in IECs and impairs macrophage bacterial clearance. Importantly, Casp6 KO reduces bactericidal activity in a cathepsin L (CTSL)-dependent manner. These findings demonstrate that preserving caspase 6 activity is essential for necroptosis prevention and effective bacterial clearance, providing new insights for future IBD therapies.

The post-translational modification ubiquitination consists in a three-step reaction triggered by E1 ubiquitin activating enzymes, E2 ubiquitin conjugating enzymes, and E3 ubiquitin ligases. The latter enzymes, providing substrate specificity, play an important role in determining the fate of the substrate proteins, by regulating their level and function. Efficient DNA damage response (DDR) is necessary to detect and signal DNA damage, thus favoring DNA damage repair to prevent genomic instability and tumorigenesis. Differently from RING (really interesting new gene)-type E3s, the ones belonging to the Homologous to E6AP C-terminus (HECT) family have an intrinsic catalytic activity, which enables them to directly transfer ubiquitin molecules to their substrates. They participate in the regulation of numerous processes, from cell proliferation to apoptosis. Nevertheless, their role in DDR and repair is less known. Recent evidence reports of the HECT E3s involvement in the regulation of DNA damage signaling, chromatin remodeling, repair pathway choice and DNA damage resolution. Further elucidating their functions in DDR and repair may provide new insights into the processes aimed at the preservation of genome integrity, putatively uncovering HECT E3s as therapeutic targets in tumors and defective DNA repair pathologies.

Dysregulated mitochondrial dynamics and macrophage-driven inflammation are essential contributors to the pathogenesis of acute kidney injury (AKI). Although the chemokine CX3CL1 has been associated with inflammatory responses, its role in AKI, particularly in regulating macrophage polarization and mitochondrial function, remains unclear. In this study, we investigated the therapeutic potential of CX3CL1 inhibition in a lipopolysaccharide (LPS)-induced AKI model. Our results found that CX3CL1 deficiency could significantly ameliorate renal dysfunction and attenuate inflammatory responses. RNA sequencing revealed that CX3CL1 deficiency alters macrophage subpopulations and gene expression profiles in the kidney, particularly affecting pathways related to immune responses and mitochondrial function. Mechanistically, the absence of CX3CL1 promotes macrophage polarization from a pro-inflammatory M1 phenotype toward an anti-inflammatory M2 phenotype. Furthermore, CX3CL1 inhibition improves mitochondrial dynamics, alleviates mitochondrial dysfunction, and reduces oxidative stress and mitochondrial DNA (mtDNA) leakage, thereby preserving mitochondrial integrity. Notably, CX3CL1 knockdown suppresses activation of the cGAS-STING pathway, a key mediator of inflammation triggered by cytosolic mtDNA. We also observed that these effects appear to be mediated through stabilization of mitochondrial transcription factor A (TFAM). Collectively, these findings identify CX3CL1 as an essential regulator of macrophage mitochondrial function and inflammation in AKI, offering a potential therapeutic target for mitigating kidney injury.

Non-small cell lung cancer (NSCLC) is characterized by the deregulation of the Hippo kinase NDR2 and high basal autophagic activity. NDR2 promotes autophagy-driven tumor growth in some cancers, but evidence in lung cancer is lacking. Human bronchial epithelial tumor cell (HBEC) lines H2030, H2030-BrM3, and H1299, with or without NDR2 depletion via siRNA or shRNA, were cultured for up to 24 h in the presence or absence of serum, and with or without the autophagosome-lysosome fusion inhibitor chloroquine (CQ). Autophagosome biogenesis, migration and Golgi apparatus functionality were analyzed. Serum deprivation of HBECs silences the expression of NDR1 but not NDR2. As shown by the increased expression of the autophagosome marker LC3-II, NDR2 participates to the formation and distribution of phagophores/autophagosomes in HBECs in an ATG9A-dependent manner. NDR2 is required for cargos degradation since its depletion disrupts lysosomal trafficking and/or fusion with autophagosomes. Finally, NDR2 silencing inhibits filopodia formation and cell polarization during HBEC migration under serum deprivation by disrupting Golgi repositioning to the leading edge, a process essential for cell migration. These data highlight NDR2's role in Golgi- and autophagy-regulated migration during starvation. Unlike NDR1, NDR2 is stabilized under starvation and promotes autophagy by regulating LC3 and ATG9A, thereby supporting NSCLC cell proliferation and migration. Routine staining for NDR2 and/or ATG9 could aid in diagnosing NSCLC with high migratory potential.

Parkinson's disease (PD) is histopathologically defined by the presence of Lewy bodies, which are intracellular proteinaceous inclusions that contain mainly aggregated alpha-synuclein (aSyn). It is believed that oligomeric intermediates between monomeric aSyn and large aggregates are neurotoxic, which would lead to the demise of dopaminergic neurons. Therefore, novel therapies preventing aSyn-induced cell death need to be developed. Therefore, we performed a genome-wide siRNA screening in an aSyn-induced dopaminergic cell death model and found the knockdown of three transforming growth factor-beta (TGFb) pathway-related genes to be protective. Hence, we hypothesized that a reduction in TGFb signaling would protect dopaminergic neurons from aSyn-induced toxicity. Thus, we validated the results of the genome-wide knockdown screening with the use of two different types of siRNAs. We confirmed that the knockdown of Activin receptor-like kinase 5 (ALK5) and Mothers against decapentaplegic homolog 2 (SMAD2), two genes of the TGFb pathway, protected dopaminergic neurons from aSyn-induced toxicity. An increase in TGFb signaling by treatment with TGFb ligands further exacerbated aSyn-induced toxicity, whereas this effect was mitigated by knockdown of ALK5, SMAD2, or Dynein light chain roadblock type-1 (DYNLRB1). Moreover, TGFb ligand treatment induced an up-regulation of SNCA mRNA expression in aSyn-overexpressing cells. Interestingly, consistent with the literature, we identified an up-regulation of the genes of the TGFb pathway in aSyn-overexpressing cells. Altogether, we identified a potential protective role by interference with the TGFb pathway against aSyn-induced toxicity. These findings provide a rationale for the development of novel strategies against PD.