[Clinicopathological characteristics and immune microenvironment of breast squamous cell carcinoma].

Objective: To investigate the clinicopathological characteristics of breast squamous cell carcinoma and to analyze the relationship between its immune microenvironment tumor infiltrating lymphocytes (TILs) and prognosis. Methods: Forty-four cases of primary squamous cell carcinoma of the breast diagnosed and treated in the First Affiliated Hospital of Air Force Medical University, Xi'an, China from January 2006 to July 2022 were selected. Their clinicopathological characteristics were analyzed. The cell composition of TILs was evaluated using immunohistochemistry (Mainly markers of B lymphocytes, T lymphocytes and plasma cells). The relationship between TILs and prognosis was also analyzed. Results: The 44 patients of breast squamous cell carcinoma were all female and all were invasive carcinoma. Eight cases (8/44, 18.2%) were squamous cell carcinoma, while 36 cases (36/44, 81.8%) were mixed squamous cell carcinoma. The mixed components included non-specific carcinoma and spindle cell metaplastic carcinoma (17 cases each). One case contained ductal carcinoma in situ of the breast and 1 case contained tubular carcinoma. The proportion of squamous cell carcinoma was 10% to 90%. The cases with pure squamous cell carcinoma often had a large cystic cavity, which was lined by atypical squamous epithelium, while infiltrating squamous cell carcinoma nests were seen in the breast tissue around the cystic cavity. Immunohistochemical staining showed that p63 and CK5/6 were expressed in the squamous cell carcinoma component, but ER, PR and HER2 were not, except for one case of HER2 1+. The positive rates of TRPS1 and PDL-1 were 76% and less than 1%, respectively. Fifteen cases were in the high TILs group (TILs≥30%) and 29 cases were in the low TILs group (TILs<30%). Twenty-three patients were followed up for 5 to 118 months. Among them, 12 died within 3 years and 9 were alive at the end of the follow up. There was no significant difference in TNM stage, TILs and prognosis between simple squamous cell carcinoma and mixed squamous cell carcinoma. Conclusions: Breast squamous cell carcinoma can be divided into simple squamous cell carcinoma and mixed squamous cell carcinoma. There are differences in gross findings and histology between the simple and mixed squamous cell carcinoma of the breast. Sufficient samples should be taken to avoid missing the diagnosis of a minor squamous component. The prognosis of patients with high TILs is significantly better than that of patients with low TILs. The expression rate of TRPS1 in primary squamous cell carcinoma of breast is high and helpful to the differential diagnosis from metastatic squamous cell carcinoma.

TRIB3 promotes the progression of renal cell carcinoma by upregulating the lipid droplet-associated protein PLIN2.

Abnormal lipid metabolism and lipid accumulation are characteristic hallmarks of renal cell carcinoma (RCC). While there is prior evidence closely linking such lipid accumulation within RCC cells and consequent tumorigenesis, the mechanisms underlying this process remain incompletely understood. In this study, a series of bioinformatics analyses were initially performed by screening RCC databases and gene sets, ultimately leading to the identification of TRIB3 as an oncogene that functions as a central regulator of lipid metabolism. TRIB3 overexpression was observed in both RCC patient tumor tissues and cell lines, and this upregulation was correlated with a worse RCC patient prognosis. When TRIB3 was knocked down, this resulted in a reduction in lipid accumulation and the consequent induction of endoplasmic reticulum (ER) stress-related apoptotic cell death. At the molecular level, interactions between TRIB3 and PLIN2 were found to abrogate TEB4-mediated PLIN2 ubiquitination and consequent degradation, thus maintaining higher PLIN2 expression levels. This simultaneously helps facilitate the accumulation of lipids while preserving ER homeostasis, thus driving accelerated RCC tumor progression. This TRIB3-PLIN2 axis thus represents a promising new target for efforts to treat RCC.

Spatiotemporal transcriptomic changes of human ovarian aging and the regulatory role of FOXP1.

Limited understanding exists regarding how aging impacts the cellular and molecular aspects of the human ovary. This study combines single-cell RNA sequencing and spatial transcriptomics to systematically characterize human ovarian aging. Spatiotemporal molecular signatures of the eight types of ovarian cells during aging are observed. An analysis of age-associated changes in gene expression reveals that DNA damage response may be a key biological pathway in oocyte aging. Three granulosa cells subtypes and five theca and stromal cells subtypes, as well as their spatiotemporal transcriptomics changes during aging, are identified. FOXP1 emerges as a regulator of ovarian aging, declining with age and inhibiting CDKN1A transcription. Silencing FOXP1 results in premature ovarian insufficiency in mice. These findings offer a comprehensive understanding of spatiotemporal variability in human ovarian aging, aiding the prioritization of potential diagnostic biomarkers and therapeutic strategies.

ELK3 destabilization by speckle-type POZ protein suppresses prostate cancer progression and docetaxel resistance.

Accumulating evidence demonstrates that the activity regulation of ELK3, a member of the E26 transformation-specific oncogene family, is critical to regulating cell proliferation, migration, and survival in human cancers. However, the molecular mechanisms of how ELK3 induces chemoresistance in prostate cancer (PCa) have not been elucidated. In this study, we found that SPOP and ELK3 are an interacting partner. The interaction between SPOP and ELK3 resulted in increased ELK3 ubiquitination and destruction, assisted by checkpoint kinase-mediated ELK3 phosphorylation. Notably, the modulation of SPOP-mediated ELK3 protein stability affected the c-Fos-induced cell proliferation and invasion of PCa cells. The clinical involvement of the SPOP-ELK3 axis in PCa development was confirmed by an immunohistochemical assay on 123 PCa tissues, with an inverse correlation between increased ELK3 and decreased SPOP being present in ~80% of the specimens. This observation was supported by immunohistochemistry analysis using a SPOP-mutant PCa specimen. Finally, docetaxel treatment induced cell death by activating checkpoint kinase- and SPOP-mediated ELK3 degradation, while SPOP-depleted or SPOP-mutated PCa cells showed cell death resistance. Notably, this observation was correlated with the protein levels of ELK3. Taken together, our study reveals the precise mechanism of SPOP-mediated degradation of ELK3 and provides evidence that SPOP mutations contribute to docetaxel resistance in PCa.

N6-methyladenosine-modified circSLCO1B3 promotes intrahepatic cholangiocarcinoma progression via regulating HOXC8 and PD-L1.

BACKGROUND: Refractoriness to surgical resection and chemotherapy makes intrahepatic cholangiocarcinoma (ICC) a fatal cancer of the digestive system with high mortality and poor prognosis. Important function invests circRNAs with tremendous potential in biomarkers and therapeutic targets. Nevertheless, it is still unknown how circRNAs contribute to the evolution of ICC. METHODS: CircRNAs in paired ICC and adjacent tissues were screened by circRNAs sequencing. To explore the impact of circRNAs on ICC development, experiments involving gain and loss of function were conducted. Various experimental techniques, including quantitative real-time PCR (qPCR), western blotting, RNA immunoprecipitation (RIP), luciferase reporter assays, RNA pull-down, chromatin immunoprecipitation (ChIP), ubiquitination assays and so on were employed to identify the molecular regulatory role of circRNAs. RESULTS: Herein, we reported a new circRNA, which originates from exon 9 to exon 15 of the SLCO1B3 gene (named circSLCO1B3), orchestrated ICC progression by promoting tumor proliferation, metastasis and immune evasion. We found that the circSLCO1B3 gene was highly overexpressed in ICC tissues and related to lymphatic metastasis, tumor sizes, and tumor differentiation. Mechanically, circSLCO1B3 not only promoted ICC proliferation and metastasis via miR-502-5p/HOXC8/SMAD3 axis, but also eradicated anti-tumor immunity via suppressing ubiquitin-proteasome-dependent degradation of PD-L1 by E3 ubiquitin ligase SPOP. We further found that methyltransferase like 3 (METTL3) mediated the m6A methylation of circSLCO1B3 and stabilizes its expression. Our findings indicate that circSLCO1B3 is a potential prognostic marker and therapeutic target in ICC patients. CONCLUSIONS: Taken together, m6A-modified circSLCO1B3 was correlated with poor prognosis in ICC and promoted ICC progression not only by enhancing proliferation and metastasis via potentiating HOXC8 expression, but also by inducing immune evasion via antagonizing PD-L1 degradation. These results suggest that circSLCO1B3 is a potential prognostic marker and therapeutic target for ICC.

Sodium Sulfite as a Novel Hypoxia Revulsant Involved in Hypoxic Regulation in Escherichia coli.

As a reducing salt, sodium sulfite could deprive oxygen in solution, which could mimic hypoxic stress in Caenorhabditis elegans. In this study, the wild-type Escherichia coli strain MG1655 was used to examine the inhibition of sodium sulfite-induced hypoxia by observing the bacterial growth curves. We also analyzed the growth curves of mutant strains (for arcA/B, soxR/S, fnr, and oxyR) related to E. coli hypoxic pathways to reveal roles of the related genes during hypoxia. The ultrastructure of hypoxia-inhibited bacteria were also observed using transmission electron microscopy. Sodium sulfite could maintain hypoxic condition of bacterial culture for 8 h with concentrations over 40 mmol/L. Complete ultrastructure of the bacteria indicated sodium sulfite did inhibit bacterial growth and division. Among the hypoxia genes, fnr and arcB played key roles in sodium sulfite-induced hypoxia. This study showed that sodium sulfite could be used as a novel hypoxia revulsant for bacterial cultures.

MiR-522-3p Attenuates Cardiac Recovery by Targeting FOXP1 to Suppress Angiogenesis.

Angiogenesis is crucial for blood supply reconstitution after myocardial infarction in patients with acute coronary syndrome (ACS). MicroRNAs are recognized as important epigenetic regulators of endothelial angiogenesis. The purpose of this study is to determine the roles of miR-522-3p in angiogenesis after myocardial infarction. The expression levels of miR-522-3p in rats' plasma and in the upper part of the ligation of the heart tissues at 28 days after myocardial infarction were significantly higher than those of the sham group. miR-522-3p mimics inhibited cell proliferations, migrations, and tube formations under hypoxic conditions in HUVECs (human umbilical vein endothelial cells), whereas miR-522-3p inhibitors did the opposite. Furthermore, studies have indicated that the inhibition of miR-522-3p by antagomir infusion promoted angiogenesis and accelerated the recovery of cardiac functions in rats with myocardial infarction.Data analysis and experimental results revealed that FOXP1 (Forkhead-box protein P1) was the target gene of miR-522-3p. Our study explored the mechanism of cardiac angiogenesis after myocardial infarction and provided a potential therapeutic approach for the treatment of ischemic heart disease in the future.

GFI1B and LSD1 repress myeloid traits during megakaryocyte differentiation.

The transcription factor Growth Factor Independence 1B (GFI1B) recruits Lysine Specific Demethylase 1 A (LSD1/KDM1A) to stimulate gene programs relevant for megakaryocyte and platelet biology. Inherited pathogenic GFI1B variants result in thrombocytopenia and bleeding propensities with varying intensity. Whether these affect similar gene programs is unknow. Here we studied transcriptomic effects of four patient-derived GFI1B variants (GFI1BT174N,H181Y,R184P,Q287*) in MEG01 megakaryoblasts. Compared to normal GFI1B, each variant affected different gene programs with GFI1BQ287* uniquely failing to repress myeloid traits. In line with this, single cell RNA-sequencing of induced pluripotent stem cell (iPSC)-derived megakaryocytes revealed a 4.5-fold decrease in the megakaryocyte/myeloid cell ratio in GFI1BQ287* versus normal conditions. Inhibiting the GFI1B-LSD1 interaction with small molecule GSK-LSD1 resulted in activation of myeloid genes in normal iPSC-derived megakaryocytes similar to what was observed for GFI1BQ287* iPSC-derived megakaryocytes. Thus, GFI1B and LSD1 facilitate gene programs relevant for megakaryopoiesis while simultaneously repressing programs that induce myeloid differentiation.

Identification of HDAC9 and ARRDC4 as potential biomarkers and targets for treatment of type 2 diabetes.

We aimed to identify the key potential insulin resistance (IR)-related genes and investigate their correlation with immune cell infiltration in type 2 diabetes (T2D). The GSE78721 dataset (68 diabetic patients and 62 controls) was downloaded from the Gene Expression Omnibus database and utilized for single-sample gene set enrichment analysis. IR-related genes were obtained from the Comparative Toxicology Genetics Database, and the final IR-differentially expressed genes (DEGs) were screened by intersecting with the DEGs obtained from the GSE78721 datasets. Functional enrichment analysis was performed, and the networks of the target gene with microRNA, transcription factor, and drug were constructed. Hub genes were identified based on a protein-protein interaction network. Least absolute shrinkage and selection operator regression and Random Forest and Boruta analysis were combined to screen diagnostic biomarkers in T2D, which were validated using the GSE76894 (19 diabetic patients and 84 controls) and GSE9006 (12 diabetic patients and 24 controls) datasets. Quantitative real-time polymerase chain reaction was performed to validate the biomarker expression in IR mice and control mice. In addition, infiltration of immune cells in T2D and their correlation with the identified markers were computed using CIBERSORT. We identified differential immune gene set regulatory T-cells in the GSE78721 dataset, and T2D samples were assigned into three clusters based on immune infiltration. A total of 2094 IR-DEGs were primarily enriched in response to endoplasmic reticulum stress. Importantly, HDAC9 and ARRDC4 were identified as markers of T2D and associated with different levels of immune cell infiltration. HDAC9 mRNA level were higher in the IR mice than in control mice, while ARRDC4 showed the opposite trend. In summary, we discovered potential vital biomarkers that contribute to immune cell infiltration associated with IR, which offers a new sight of immunotherapy for T2D.

A function of spalt major as a sequence-specific DNA binding transcription factor mediates repression of knirps in the Drosophila wing imaginal disc.

The Spalt transcriptional regulators participate in a variety of cell fate decisions during multicellular development. Vertebrate Spalt proteins have been mostly associated to the organization of heterochromatic regions, but they also contribute regulatory functions through binding to A/T rich motives present in their target genes. The developmental processes in which the Drosophila spalt genes participate are well known through genetic analysis, but the mechanism by which the Spalt proteins regulate transcription are still unknown. Furthermore, despite the prominent changes in gene expression associated to mutations in the spalt genes, the specific DNA sequences they bind are unknow. Here, we analyze a DNA fragment present in the regulatory region of the knirps gene. Spalt proteins are candidate repressors of knirps expression during the formation of the venation pattern in the wing disc, and we identified a minimal conserved 30bp sequence that binds to Spalt major both in vivo and in vitro. This sequence mediates transcriptional repression in the central region of the wing blade, constituting the first confirmed case of a direct regulatory interaction between Spalt major and its target DNA in Drosophila. Interestingly, we also find similar sequences in a set of eight novel candidate Spalt target genes, pointing to a common mechanism of transcriptional repression mediated by Spalt proteins.

Mesenchymal stem cells-derived exosomes carrying microRNA-30b confer protection against pulmonary fibrosis by downregulating Runx1 via Spred2.

Idiopathic pulmonary fibrosis (IPF) is a chronic pulmonary fibrosis disease that is fatal. Mesenchymal stem cells (MSCs)-secreted exosomes (exos) have been linked to improving PF. Moreover, exosomal microRNAs (miRs) can control the growth of numerous diseases, including lung disorders. Our bioinformatics analysis showed that miR-30b was downregulated in tissue samples from surgical remnants of biopsies or lungs explanted from patients with IPF who underwent pulmonary transplantation. This suggests that miR-30b plays an important role in both the pathogenesis and treatment of IPF. Herein, this research was designed to ascertain the mechanism of MSCs-exos-packaged miR-30b in alleviating PF. The serum was harvested from idiopathic PF (IPF) patients with interstitial pneumonia caused by dermatomyositis and the MLE12 lung epithelial cell fibrosis model was built with TGF-ß1 (10 ng/mL), followed by miR-30b expression determination. TGF-ß1-stimulated MLE12 cells were co-incubated with exos from MSCs with or without Spred2 or Runx1 overexpression, followed by measurement of cell viability and apoptosis. After establishing the IPF mouse model with bleomycin and injecting exos and/or silencing and overexpressing adenovirus vectors, fibrosis evaluation was conducted. In mice and cells, the expression of TGF-ß1, TNF-α, and IL-1ß was tested via ELISA, and the levels of E-cad, ZO-1, α-SMA, and collagen type I via western blot analysis. The promoters of miR-30b, Runx1, and Spred2 were investigated. miR-30b was downregulated in the serum of IPF patients and TGF-ß1-stimulated MLE12 cells. Mechanistically, miR-30b inhibited Spred2 transcription by negatively targeting Runx1. MSCs-exos or MSCs-exo-miR-30b decreased the apoptosis, inflammation, and fibrosis while increasing their viability in TGF-ß1-stimulated MLE12 cells, which was annulled by overexpressing Runx1 or Spred2. Exo-miR-30b decreased Runx1 expression to downregulate Spred2, reducing fibrosis and inflammation in IPF mice. Our results indicated that MSCs-exos-encapsulated miR-30b had a potential function to inhibit PF and part of its function may be achieved by targeting RUNX1 to reduce the Spred2 transcription level. Moreover, this work offered evidence and therapeutic targets for therapeutic strategies for managing clinical PF in patients.

TRIB3 promotes malignancy of head and neck squamous cell carcinoma via inhibiting ferroptosis.

Tribbles pseudokinase 3 (TRIB3) has been identified recently as a novel oncogene in several cancers. Still, further extensive research is imperative to elucidate its function and the molecular mechanisms underlying its involvement in the progression of head and neck squamous cell carcinoma (HNSCC). In our study, we found that TRIB3 silencing significantly promoted cell death by inducing ferroptosis. The interaction of TRIB3 with Transcription Factor 4 (TCF4) and ß-catenin created a heterotrimeric complex, which directly interacts with the ALOXE3 promoter, detrimentally impacting its activation. The consequential partial neutralization of ferroptosis induced by TRIB3 deficiency is observed through the implementation of ALOXE3 knockdown. Furthermore, the study demonstrated that the molecular inhibitor hesperidin, targeting TRIB3, not only reduced cell malignancy but also induced ferroptosis, thereby suppressing tumor growth. Overall, our findings unequivocally validate the proposition that TRIB3 deficiency precipitates the iron death mechanism, thereby indicating that the strategic targeting of TRIB3 could emerge as an innovative therapeutic strategy for HNSCC.

SP140 inhibitor suppressing TRIM22 expression regulates glioma progress through PI3K/AKT signaling pathway.

BACKGROUND: SP gene family, consisting of SP100, SP110, SP140, and SP140L, has been implicated in the initiation and advancement of numerous malignancies. Nevertheless, their clinical significance in glioma remains incompletely understood. METHOD: Expression levels and prognostic significance of SP family members were evaluated in the TCGA and CGGA datasets. Multifactorial analysis was used to identify SP gene family members that can independently impact the prognosis of glioma patients. A SP140-based predictive risk model/nomogram was developed in TCGA dataset and validated in CGGA dataset. The model's performance was evaluated through receiver operating characteristic (ROC) curves, calibration plots, and decision curve analyses. Phenotypic associations of SP140 and TRIM22 were examined through CancerSEA and TIMER. The effect of SP140 inhibitor in glioma progress and TRIM22/PI3K/AKT signaling pathway was confirmed in U251/U87 glioma cells. RESULTS: The SP family members exhibited elevated expression in gliomas and were negatively correlated with prognosis. SP140 emerged as an independent prognostic factor, and a SP140-based nomogram/predictive risk model demonstrated high accuracy. SP140 inhibitor, GSK761, lead to the suppression of TRIM22 expression and the PI3K/AKT signaling pathway. GSK761 also restrain glioma proliferation, migration, and invasion. Furthermore, SP140 and TRIM22 coexpressed in glioma cells with high level of vascular proliferation, TRIM22 is closely associated with the immune cell infiltration. CONCLUSION: SP140-based nomogram proved to be a practical tool for predicting the survival of glioma patients. SP140 inhibitor could suppress glioma progress via TRIM22/PI3K/AKT signaling pathway.

Inhibition of PRMT1 Suppresses the Growth of U87MG-Derived Glioblastoma Stem Cells by Blocking the STAT3 Signaling Pathway.

Glioblastoma stem cells (GSCs) play a pivotal role in the initiation, progression, resistance to treatment, and relapse of glioblastoma multiforme (GBM). Thus, identifying potential therapeutic targets and drugs that interfere with the growth of GSCs may contribute to improved treatment outcomes for GBM. In this study, we first demonstrated the functional role of protein arginine methyltransferase 1 (PRMT1) in GSC growth. Furamidine, a PRMT1 inhibitor, effectively inhibited the proliferation and tumorsphere formation of U87MG-derived GSCs by inducing cell cycle arrest at the G0/G1 phase and promoting the intrinsic apoptotic pathway. Moreover, furamidine potently suppressed the in vivo tumor growth of U87MG GSCs in a chick embryo chorioallantoic membrane model. In particular, the inhibitory effect of furamidine on U87MG GSC growth was associated with the downregulation of signal transducer and activator of transcription 3 (STAT3) and key GSC markers, including CD133, Sox2, Oct4, Nanog, aldehyde dehydrogenase 1, and integrin α6. Our results also showed that the knockdown of PRMT1 by small interfering RNA significantly inhibited the proliferation of U87MG GSCs in vitro and in vivo through a molecular mechanism similar to furamidine. In addition, combined treatment with furamidine and berbamine, a calcium/calmodulin-dependent protein kinase II gamma (CaMKIIγ) inhibitor, inhibited the growth of U87MG GSCs more strongly than single-compound treatment. The increased antiproliferative effect of combining the two compounds resulted from a stronger downregulation of STAT3-mediated downstream GBM stemness regulators through dual PRMT1 and CaMKIIγ function blockade. In conclusion, these findings suggest that PRMT1 and its inhibitor, furamidine, are potential novel therapeutic targets and drug candidates for effectively suppressing GSC growth.

Endothelial ß-catenin upregulation and Y142 phosphorylation drive diabetic angiogenesis via upregulating KDR/HDAC9.

BACKGROUND: Diabetic angiogenesis is closely associated with disabilities and death caused by diabetic microvascular complications. Advanced glycation end products (AGEs) are abnormally accumulated in diabetic patients and are a key pathogenic factor for diabetic angiogenesis. The present study focuses on understanding the mechanisms underlying diabetic angiogenesis and identifying therapeutic targets based on these mechanisms. METHODS: In this study, AGE-induced angiogenesis serves as a model to investigate the mechanisms underlying diabetic angiogensis. Mouse aortic rings, matrigel plugs, and HUVECs or 293T cells were employed as research objects to explore this pathological process by using transcriptomics, gene promoter reporter assays, virtual screening and so on. RESULTS: Here, we found that AGEs activated Wnt/ß-catenin signaling pathway and enhanced the ß-catenin protein level by affecting the expression of ß-catenin degradation-related genes, such as FZDs (Frizzled receptors), LRPs (LDL Receptor Related Proteins), and AXIN1. AGEs could also mediate ß-catenin Y142 phosphorylation through VEGFR1 isoform5. These dual effects of AGEs elevated the nuclear translocation of ß-catenin and sequentially induced the expression of KDR (Kinase Insert Domain Receptor) and HDAC9 (Histone Deacetylase 9) by POU5F1 and NANOG, respectively, thus mediating angiogenesis. Finally, through virtual screening, Bioymifi, an inhibitor that blocks VEGFR1 isoform5-ß-catenin complex interaction and alleviates AGE-induced angiogenesis, was identified. CONCLUSION: Collectively, this study offers insight into the pathophysiological functions of ß-catenin in diabetic angiogenesis.

The impact of DNA methylation on CTCF-mediated 3D genome organization.

Cytosine DNA methylation is a highly conserved epigenetic mark in eukaryotes. Although the role of DNA methylation at gene promoters and repetitive elements has been extensively studied, the function of DNA methylation in other genomic contexts remains less clear. In the nucleus of mammalian cells, the genome is spatially organized at different levels, and strongly influences myriad genomic processes. There are a number of factors that regulate the three-dimensional (3D) organization of the genome, with the CTCF insulator protein being among the most well-characterized. Pertinently, CTCF binding has been reported as being DNA methylation-sensitive in certain contexts, perhaps most notably in the process of genomic imprinting. Therefore, it stands to reason that DNA methylation may play a broader role in the regulation of chromatin architecture. Here we summarize the current understanding that is relevant to both the mammalian DNA methylation and chromatin architecture fields and attempt to assess the extent to which DNA methylation impacts the folding of the genome. The focus is in early embryonic development and cellular transitions when the epigenome is in flux, but we also describe insights from pathological contexts, such as cancer, in which the epigenome and 3D genome organization are misregulated.

Peeling the onion: additional layers of regulation in the acid stress response.

Bacteria are capable of withstanding large changes in osmolality and cytoplasmic pH, unlike eukaryotes that tightly regulate their pH and cellular composition. Previous studies on the bacterial acid stress response described a rapid, brief acidification, followed by immediate recovery. More recent experiments with better pH probes have imaged single living cells, and we now appreciate that following acid stress, bacteria maintain an acidic cytoplasm for as long as the stress remains. This acidification enables pathogens to sense a host environment and turn on their virulence programs, for example, enabling survival and replication within acidic vacuoles. Single-cell analysis identified an intracellular pH threshold of ~6.5. Acid stress reduces the internal pH below this threshold, triggering the assembly of a type III secretion system in Salmonella and the secretion of virulence factors in the host. These pathways are significant because preventing intracellular acidification of Salmonella renders it avirulent, suggesting that acid stress pathways represent a potential therapeutic target. Although we refer to the acid stress response as singular, it is actually a complex response that involves numerous two-component signaling systems, several amino acid decarboxylation systems, as well as cellular buffering systems and electron transport chain components, among others. In a recent paper in the Journal of Bacteriology, M. G. Gorelik, H. Yakhnin, A. Pannuri, A. C. Walker, C. Pourciau, D. Czyz, T. Romeo, and P. Babitzke (J Bacteriol 206:e00354-23, 2024, https://doi.org/10.1128/jb.00354-23) describe a new connection linking the carbon storage regulator CsrA to the acid stress response, highlighting new additional layers of complexity.

NSUN5/TET2-directed chromatin-associated RNA modification of 5-methylcytosine to 5-hydroxymethylcytosine governs glioma immune evasion.

Malignant glioma exhibits immune evasion characterized by highly expressing the immune checkpoint CD47. RNA 5-methylcytosine(m5C) modification plays a pivotal role in tumor pathogenesis. However, the mechanism underlying m5C-modified RNA metabolism remains unclear, as does the contribution of m5C-modified RNA to the glioma immune microenvironment. In this study, we demonstrate that the canonical 28SrRNA methyltransferase NSUN5 down-regulates ß-catenin by promoting the degradation of its mRNA, leading to enhanced phagocytosis of tumor-associated macrophages (TAMs). Specifically, the NSUN5-induced suppression of ß-catenin relies on its methyltransferase activity mediated by cysteine 359 (C359) and is not influenced by its localization in the nucleolus. Intriguingly, NSUN5 directly interacts with and deposits m5C on CTNNB1 caRNA (chromatin-associated RNA). NSUN5-induced recruitment of TET2 to chromatin is independent of its methyltransferase activity. The m5C modification on caRNA is subsequently oxidized into 5-hydroxymethylcytosine (5hmC) by TET2, which is dependent on its binding affinity for Fe2+ and α-KG. Furthermore, NSUN5 enhances the chromatin recruitment of RBFOX2 which acts as a 5hmC-specific reader to recognize and facilitate the degradation of 5hmC caRNA. Notably, hmeRIP-seq analysis reveals numerous mRNA substrates of NSUN5 that potentially undergo this mode of metabolism. In addition, NSUN5 is epigenetically suppressed by DNA methylation and is negatively correlated with IDH1-R132H mutation in glioma patients. Importantly, pharmacological blockage of DNA methylation or IDH1-R132H mutant and CD47/SIRPα signaling synergistically enhances TAM-based phagocytosis and glioma elimination in vivo. Our findings unveil a general mechanism by which NSUN5/TET2/RBFOX2 signaling regulates RNA metabolism and highlight NSUN5 targeting as a potential strategy for glioma immune therapy.

PRMT1 promotes pancreatic cancer development and resistance to chemotherapy.

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal types of cancer, and novel treatment regimens are direly needed. Epigenetic regulation contributes to the development of various cancer types, but its role in the development of and potential as a therapeutic target for PDAC remains underexplored. Here, we show that PRMT1 is highly expressed in murine and human pancreatic cancer and is essential for cancer cell proliferation and tumorigenesis. Deletion of PRMT1 delays pancreatic cancer development in a KRAS-dependent mouse model, and multi-omics analyses reveal that PRMT1 depletion leads to global changes in chromatin accessibility and transcription, resulting in reduced glycolysis and a decrease in tumorigenic capacity. Pharmacological inhibition of PRMT1 in combination with gemcitabine has a synergistic effect on pancreatic tumor growth in vitro and in vivo. Collectively, our findings implicate PRMT1 as a key regulator of pancreatic cancer development and a promising target for combination therapy.

Control of meiotic entry by dual inhibition of a key mitotic transcription factor.

The mitosis to meiosis transition requires dynamic changes in gene expression, but whether and how the mitotic transcriptional machinery is regulated during this transition is unknown. In budding yeast, SBF and MBF transcription factors initiate the mitotic gene expression program. Here, we report two mechanisms that work together to restrict SBF activity during meiotic entry: repression of the SBF-specific Swi4 subunit through LUTI-based regulation and inhibition of SBF by Whi5, a functional homolog of the Rb tumor suppressor. We find that untimely SBF activation causes downregulation of early meiotic genes and delays meiotic entry. These defects are largely driven by the SBF-target G1 cyclins, which block the interaction between the central meiotic regulator Ime1 and its cofactor Ume6. Our study provides insight into the role of SWI4LUTI in establishing the meiotic transcriptional program and demonstrates how the LUTI-based regulation is integrated into a larger regulatory network to ensure timely SBF activity.