Cell Communication and Signaling最新文献

Background: Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) that is associated with increased risk of developing colitis-associated carcinoma (CAC). The genetic profile of CACs is fairly similar to the sporadic colorectal carcinomas (sCRCs), although showing certain differences in the timing and sequence of alterations that contribute to carcinogenesis. Also, both cancer types typically show a strong histological resemblance, which complicates the pathologists' diagnosis. Due to the different clinical consequences, it is of utmost importance to categorize the corresponding cancer type correctly.

Methods: In this study, we determined the mutation profiles of 64 CACs and sCRCs in the hotspot regions of 50 cancer-associated genes and compared them to 29 controls to identify genetic gene variants that can facilitate the pathologists' diagnosis. Pearson Chi-Square or Fisher's exact tests were used for statistical analyses.

Results: We found that sCRCs tend to mutate more frequently in APC and PIK3CA genes than CACs and that mainly males were affected. Our CAC cohort identified the KRAS G12D mutation as group-specific variant that was not detected in the sCRCs. When separating conventional from non-conventional CACs, it was discovered that the conventional type shows significantly more mutations for ATM.

Conclusions: Taken together, our data highlights genetic differences between sCRC and CAC and enables the possibility to utilize specific gene alterations to support the pathologist's diagnosis.

Background: Stress-induced activation of ERK/Drp1 serves as a checkpoint in the segregation of damaged mitochondria for autophagic clearance (mitophagy). Elevated cytosolic calcium (Ca²⁺) activates ERK, which is pivotal to mitophagy initiation. This process is altered in Parkinson's disease (PD) with mutations in leucine-rich repeat kinase 2 (LRRK2), potentially contributing to mitochondrial dysfunction. Pathogenic LRRK2 mutation is linked to dysregulated cellular Ca²⁺ signaling but the mechanism involved remains unclear.

Methods: Mitochondrial damages lead to membrane depolarization. To investigate how LRRK2 mutation impairs cellular response to mitochondrial damages, mitochondrial depolarization was induced by artificial uncoupler (FCCP) in wild-type (WT) and LRRK2^R1441G mutant knockin (KI) mouse embryonic fibroblasts (MEFs). The resultant cytosolic Ca²⁺ flux was assessed using live-cell Ca²⁺ imaging. The role of mitochondria in FCCP-induced cytosolic Ca²⁺ surge was confirmed by co-treatment with the mitochondrial sodium-calcium exchanger (NCLX) inhibitor. Cellular mitochondrial quality and function were evaluated by Seahorse™ real-time cell metabolic analysis, flow cytometry, and confocal imaging. Mitochondrial morphology was visualized using transmission electron microscopy (TEM). Activation (phosphorylation) of stress response pathways were assessed by immunoblotting.

Results: Acute mitochondrial depolarization induced by FCCP resulted in an immediate cytosolic Ca²⁺ surge in WT MEFs, mediated predominantly via mitochondrial NCLX. However, such cytosolic Ca²⁺ response was abolished in LRRK2 KI MEFs. This loss of response in KI was associated with impaired activation of Ca²⁺/calmodulin-dependent kinase II (CaMKII) and MEK, the two upstream kinases of ERK. Treatment of LRRK2 inhibitor did not rescue this phenotype indicating that it was not caused by mutant LRRK2 kinase hyperactivity. KI MEFs exhibited swollen mitochondria with distorted cristae, depolarized mitochondrial membrane potential, and reduced mitochondrial Ca²⁺ store and mitochondrial calcium uniporter (MCU) expression. These mutant cells also exhibited lower cellular ATP: ADP ratio albeit higher basal respiration than WT, indicating compensation for mitochondrial dysfunction. These defects may hinder cellular stress response and signals to Drp1-mediated mitophagy, as evident by impaired mitochondrial clearance in the mutant.

Conclusions: Pathogenic LRRK2^R1441G mutation abolished mitochondrial depolarization-induced Ca²⁺ response and impaired the basal mitochondrial clearance. Inherent defects from LRRK2 mutation have weakened the cellular ability to scavenge damaged mitochondria, which may further aggravate mitochondrial dysfunction and neurodegeneration in PD.

As most traditional drugs used to treat central nervous system (CNS) diseases have a single therapeutic target, many of them cannot treat complex diseases or diseases whose mechanism is unknown and cannot effectively reverse the root changes underlying CNS diseases. This raises the question of whether multiple functional components are involved in the complex pathological processes of CNS diseases. Organelles are the core functional units of cells, and the replacement of damaged organelles with healthy organelles allows the multitargeted and integrated modulation of cellular functions. The development of therapies that target independent functional units in the cell, specifically, organelle-based therapies, is rapidly progressing. This article comprehensively discusses the pathogenesis of mitochondrial homeostasis disorders, which involve mitochondria, one of the most important organelles in CNS diseases, and the machanisms of mitochondrion-based therapies, as well as current preclinical and clinical studies on the efficacy of therapies targeting mitochondrial to treat CNS diseases, to provide evidence for use of organelle-based treatment strategies in the future.

The Wnt/β-catenin signaling pathway is crucial for embryonic development and adult tissue homeostasis. Dysregulation of Wnt signaling is linked to various developmental anomalies and diseases, notably cancer. Although numerous regulators of the Wnt signaling pathway have been identified, their precise function during mouse embryo development remains unclear. Here, we revealed that TMEM132A is a crucial regulator of canonical Wnt/β-catenin signaling in mouse development. Mouse embryos lacking Tmem132a displayed a range of malformations, including open spina bifida, caudal truncation, syndactyly, and renal defects, similar to the phenotypes of Wnt/β-catenin mutants. Tmem132a knockdown in cultured cells suppressed canonical Wnt/β-catenin signaling. In developing mice, loss of Tmem132a also led to diminished Wnt/β-catenin signaling. Mechanistically, we showed that TMEM132A interacts with the Wnt co-receptor LRP6, thereby stabilizing it and preventing its lysosomal degradation. These findings shed light on a novel role for TMEM132A in regulating LRP6 stability and canonical Wnt/β-catenin signaling during mouse embryo development. This study provides valuable insights into the molecular intricacies of the Wnt signaling pathway. Further research may deepen our understanding of Wnt pathway regulation and offer its potential therapeutic applications.

Background: Type I interferons (IFN-I) are potent alarm factors that initiate cancer cell elimination within tumors by the immune system. This critical immune response is often suppressed in aggressive tumors, thereby facilitating cancer immune escape and unfavorable patient outcome. The mechanisms underpinning IFN-I suppression in tumors are incompletely understood. Arginase-1 (ARG1)-expressing immune cells that infiltrate tumors can restrict arginine availability by ARG1-mediated arginine degradation. We hypothesized that arginine restriction suppresses the IFN-I response in tumors.

Methods: Comprehensive, unbiased open approach omics analyses, various in vitro techniques, including microscopy, qPCR, immunoblotting, knock-down experiments, and flow cytometry were employed, as well as ex vivo analysis of tumor tissue from mice. Several functional bioassays were utilized to assess metabolic functions and autophagy activity in cancer cells.

Results: Arginine restriction potently induced expression of selective autophagy receptors, enhanced bulk and selective autophagy and strongly suppressed the IFN-I response in cancer cells in an autophagy-dependent manner.

Conclusion: Our study proposes a mechanism for how tumor-infiltrating immune cells can promote cancer immune escape by dampening the IFN-I response. We suggest ARG1 and autophagy as putative therapeutic targets to activate the IFN-I response in tumors.

Background: Cellular senescence can be induced in mammalian tissues by multiple stimuli, including aging, oncogene activation and loss of tumor suppressor genes, and various types of stresses. While senescence is a tumor suppressing mechanism when induced within premalignant or malignant tumor cells, senescent cells can promote cancer development through increased secretion of growth factors, cytokines, chemokines, extracellular matrix, and degradative enzymes, collectively known as senescence-associated secretory phenotype (SASP). Previous studies indicated that senescent cells, through SASP factors, stimulate tumor cell invasion that is a critical step in cancer cell metastasis.

Methods: In the current study, we investigated the effect of senescent cells on the motility of breast cancer cells, which is another key step in cancer cell metastasis. We analyzed the motility of breast cancer cells co-cultured with senescent cells in vitro and metastasis of the breast cancer cells co-injected with senescent cells in orthotopic xenograft models. We also delineated the signaling pathway mediating the effect of senescent cells on cancer cell motility.

Results: Our results indicate that senescent cells stimulated the migration of breast cancer cells through secretion of GM-CSF and bFGF, which in turn induced activation of the JNK pathway in cancer cells. More importantly, senescent cells promoted breast cancer metastasis, with a minimum effect on the primary tumor growth, in orthotopic xenograft mouse models.

Conclusions: These results have revealed an additional mechanism by which senescent cells promote tumor cell metastasis and tumor progression, and will potentially lead to identification of novel targets for cancer therapies that suppress metastasis, the major cause of cancer mortality.

Glioblastoma (GB) is a highly heterogeneous type of incurable brain cancer with a low survival rate. Intensive ongoing research has identified several potential targets; however, GB is marred by the activation of multiple pathways, and thus common targets are highly sought. The signal regulatory scaffold IQGAP1 is an oncoprotein implicated in GB. IQGAP1 nucleates a myriad of pathways in a contextual manner and modulates many of the targets altered in GB like MAPK, NF-κB, and mTOR/PI3K/Akt1, thus positioning it as a plausible common therapeutic target. Here, we review the targets that are subjects of GB treatment clinical trials and the commonly used animal models that facilitate target identification. We propose a model in which the dysfunction of various IQGAP1 pathways can explain to a larger extent some of the GB heterogeneity and offer a platform for personalized medicine.

Background: Our previous study has demonstrated a decreased colonic CD8⁺CD39⁺ T cells, enrichment of granzyme A (GZMA), was found in pediatric-onset colitis and inflammatory bowel disease (IBD) characterized by impaired intestinal barrier function. However, the influence of GZMA on intestinal barrier function remains unknown.

Methods: Western blotting(WB), real-time PCR (qPCR), immunofluorescence (IF) and in vitro permeability assay combined with intestinal organoid culture were used to detect the effect of GZMA on intestinal epithelial barrier function in vivo and in vitro. Luciferase, immunoprecipitation (IP) and subcellular fractionation isolation were performed to identify the mechanism through which GZMA modulated intestinal epithelial barrier function.

Results: Herein, we, for the first time, demonstrated that CD8⁺CD39⁺ T cells promoted intestinal epithelial barrier function through GZMA, leading to induce Occludin(OCLN) and Zonula Occludens-1(ZO-1) expression, which was attributed to enhanced CDX2-mediated cell differentiation caused by increased glutathione peroxidase 4(GPX4)-induced ferroptosis inhibition in vivo and in vitro. Mechanically, GZMA inhibited intestinal epithelial cellular PDE4B activation to trigger cAMP/PKA/CREB cascade signaling to increase CREB nuclear translocation, initiating GPX4 transactivity. In addition, endogenous PKA interacted with CREB, and this interaction was enhanced in response to GZMA. Most importantly, administration of GZMA could alleviate DSS-induced colitis in vivo.

Conclusion: These findings extended the novel insight of GZMA contributed to intestinal epithelial cell differentiation to improve barrier function, and enhacement of GZMA could be a promising strategy to patients with IBD.