Transcription Factor Sp1 Research Articles

Profibrotic role of transcription factor SP1 in cross-talk between fibroblasts and M2 macrophages

Profibrotic role of transcription factor SP1 in cross-talk between fibroblasts and M2 macrophages

Folic acid blocks ferroptosis induced by cerebral ischemia and reperfusion through regulating folate hydrolase transcriptional adaptive program

Cerebral ischemia-reperfusion (I/R) injury is notably linked with folic acid (FA) deficiency. The aim of our investigation was to explore the effects and underlying mechanisms by which FA mitigates I/R, specifically through regulating the GCPII transcriptional adaptive program. Initially, we discovered that following cerebral I/R, levels of FA, methionine synthase (MTR), and methylenetetrahydrofolate reductase (MTHFR) were decreased, while GCPII expression was elevated. Secondly, administering FA could mitigate cognitive impairment and neuronal damage induced by I/R. Thirdly, the mechanism of FA supplementation involved suppressing the transcriptional factor Sp1, subsequently inhibiting GCPII transcription, reducing Glu content, obstructing cellular ferroptosis, and alleviating cerebral I/R injury. In summary, our data demonstrate that FA affords protection against cerebral I/R injury by inhibiting the GCPII transcriptional adaptive response. These findings unveil that targeting GCPII might be a viable therapeutic strategy for cerebral I/R.

Structure of a DNA G-quadruplex that Modulates SP1 Binding Sites Architecture in HIV-1 Promoter

Nucleic acid sequences containing guanine tracts are able to form non-canonical DNA or RNA structures known as G-quadruplexes (or G4s). These structures, based on the stacking of G-tetrads, are involved in various biological processes such as gene expression regulation. Here, we investigated a G4 forming sequence, HIVpro2, derived from the HIV-1 promoter. This motif is located 60 nucleotides upstream of the proviral Transcription Starting Site (TSS) and overlaps with two SP1 transcription factor binding sites. Using NMR spectroscopy, we determined that HIVpro2 forms a hybrid type G4 structure with a core that is interrupted by a single nucleotide bulge. An additional reverse-Hoogsteen AT base pair is stacked on top of the tetrad. SP1 transcription factor is known to regulate transcription activity of many genes through the recognition of Guanine-rich duplex motifs. Here, the formation of HIVpro2 G4 may modulate SP1 binding sites architecture by competing with the formation of the canonical duplex structure. Such DNA structural switch potentially participates to the regulation of viral transcription and may also interfere with HIV-1 reactivation or viral latency.

Effect of hydroxyurea on SP1, LIN28B, IGF2BP3, COL4A5, BCL2, gamma globin genes expression: an in vitro study

BackgroundIn some β-thalassemia intermedia patients, hydroxyurea (HU) increases hemoglobin and HbF levels. However, HUs’ effects molecular mechanism is still unclear.MethodsIn this study, a weighted gene co-expression network analysis was conducted on the GSE109186 dataset. The genes LIN28A, COL4A5, SP1, BCL2, and IGF2BP3 were identified as hub genes involved in the γ-gene switching process. The effect of HU treatment at doses of 50, 100, and 150 μM for 12, 24, and 48 h on the K562 cell line was examined by using qRT-PCR to measure the expression levels of these hub genes.ResultsSP1 gene expression decreased after treatment with 50, 100, and 150 μM HU for 12, 24, and 48 h. The expression of the LIN28A gene was tripled at three concentrations of 50, 100, and 150 μM for 12 h. The IGF2BP3 gene expression was doubled after 24 and 48 h at a concentration of 150 μM HU. Regarding COL4A5 gene expression, except at 12 h after treatment at a concentration of 50 μM, a significant increase was observed in other concentrations and times. The BCL2 gene expression pattern at all concentrations decreased significantly after 12 h. The γ gene showed a significant increase compared to the control group after 24 and 48 h at the different concentrations.ConclusionThe results showed that in HU-treated cells, changes in the expression of LIN28A, COL4A5, SP1, and IGF2BP3 genes were accompanied by an increase in γ-gene expression. By elucidating precisely the mechanism of γ-to-β gene switching, we can hope for less complicated drugs.

Loss of CCAAT‐Enhancer Binding Protein Delta Promotes Acute Myeloid Leukemia Cell Proliferation and Survival By Upregulating Cyclin D1 Expression

Despite improvements in the treatment options, acute myeloid leukemia (AML) remains a fatal malignancy with an estimated 5-year relative survival rate of 31.7%. There is continued need for identification of new disease drivers to develop novel therapeutic options and improve clinical outcomes. Dysregulated transcriptional landscapes are associated with disease pathogenesis and treatment responses. To identify new disease drivers of AML, we analyzed RNA-Seq data from 59 patient-matched diagnosis and relapse (PAML) specimens (study cohort). A set of five differentially expressed genes (DEGs; STAT4, XRCC2, USP3, CEBPD, RBM47) with concordant changes in expression between diagnosis and relapse (Figure 1A) were selected for study using the following criteria: (a) concordant differential expression (DESeq2: log2FC > |1.2| and q < 0.05) in at least 25% of the relapsed patients in the study cohort (b) concordant differential expression in independent datasets of RNA-Seq without any experimental validation, and (c) high cancer driver potential based on their molecular function. Binding analysis for regulation of transcription (BART) on DEGs between normal CD34 + cells, diagnosis and relapsed AML patient specimens suggested that CEBPD could function as a transcriptional regulator of a subset of the DEGs. We hypothesized that dysregulated expression of these genes promotes AML disease progression. To examine their role in AML, we altered their expression in AML cell line models and measured changes in AML cell phenotypes. Of these genes, CRISPR-mediated knockdown of the transcription factor CCAAT/enhancer-binding protein delta (CEBPD) enhanced AML cell proliferation, self-renewal capacity, and survival of the relapsed AML cell line OCI-AML5. CEBPD knockdown also conferred OCI-AML5 resistance to cytarabine - a common chemotherapy drug used for AML treatment. Short hairpin RNA (shRNA)-mediated knockdown of CEBPD in OCI-AML5 validated these results. CRISPR-mediated upregulation of CEBPD expression induced monocyte/macrophage differentiation marker CD14 expression and enhanced apoptosis rates in OCI-AML5 cells. CEBPD upregulation also induced differentiation in the diagnosis AML cell line OCI-AML2. Survival analyses showed that lower expression of CEBPD was significantly associated with poor survival in pediatric AML patients, and there was a trend of lower CEBPD expression associating with worse survival in adult AML patients (UCSC Xena browser). These results altogether suggest that CEBPD plays a tumor suppressor role in AML. Gene set enrichment analyses (GSEA) on RNA-Seq data revealed significant positive enrichment of cell proliferation pathways upon CEBPD knockdown in OCI-AML5 cells as well as in a subset of the PAML patients with downregulated CEBPD expression at relapse. Differential gene expression and GSEA analyses altogether suggested upregulated cyclin D1 as one of the downstream drivers of enhanced growth of AML cells with repressed CEBPD expression (Figure 1B). RT-qPCR and Western Blot experiments confirmed upregulation of CCND1 expression in CEBPD knockdown OCI-AML5 and OCI-AML2 cells. Next, we sought to understand the molecular mechanisms repressing CEBPD expression during AML disease progression. We found an inverse association between CEBPD and DNMT3 methyltransferases mRNA expression in PAML and independent datasets. Treatment with the hypomethylating agent azacitidine upregulated CEBPD mRNA expression in multiple AML cell lines including OCI-AML5 and OCI-AML2, suggesting that hypermethylation represses CEBPD gene expression in these AML cells. Integrative analysis of gene expression with DNA methylation at the CEBPD promoter identified hypermethylation of multiple CpGs within the binding region of the transcription factor Sp1 in a subset of patients with CEBPD downregulation. CpG methylation has been shown to interfere with Sp1 binding at the CEBPD promoter. Since Sp1 binding promotes CEBPD transcription, hypermethylation at these sites may repress CEBPD expression during AML disease progression. Our study suggests that CEBPD can function as tumor suppressor in AML. Results suggest a role for DNA methylation in repressing CEBPD expression during AML disease progression. Furthermore, we show that CEBPD repression promotes AML cells' growth potentially via inducing the expression of the cell cycle driver CCND1.

Over-expression of cFos by the Transcription Factors NFATc2 and Sp1 in Pancreatic Cancer Cells.

The transcription factors NFATc2 and Sp1 play a key role in the progression of pancreatic cancer because they interact inside the cells and exert their carcinogenic effect through transcriptional modification. Drugs can also induce a variety of oncogenic signalling cascades. The risk of tumour progression and metastasis seems to be significantly increased in the perioperative period. Our research group has previously demonstrated the function of the interaction between NFATc2 and Sp1 in pancreatic cancer and has identified the proto-oncogene cFos as a target gene. We also found that the anaesthetic drug propofol has anti-tumour properties. The aim of the present study was to investigate the effect of propofol on the expression of the transcription factors NFATc2, Sp1 and cFos in the pancreatic cancer cell lines PaTu 8988t and PANC-1 and to analyse the relevance of this effect for the cells. Stimulation with propofol and its effects on the expression of NFATc2, Sp1 and cFos were assessed by immunoblot. Cell cycle distribution was analysed by flow cytometry, and cell proliferation was measured with the ELISA BrdU assay. Propofol and siRNA against cFos were used for stimulation. Propofol regulated the expression of NFATc2, Sp1 and cFos. Stimulation with 250 µM or 500 µM propofol decreased NFATc2, Sp1 and cFos signalling in the Western blot analysis. At the same time, propofol significantly inhibited proliferation and activated cell cycle. The same proliferation behaviour was observed after transient cFos inhibition. These effects were potentiated by simultaneous stimulation with propofol and transient inhibition of cFos, further inhibiting cell proliferation. Interestingly, the cell cycle activation observed after stimulation with propofol alone was reversed in both cell lines. Anaesthetists only see oncological patients in a short time window. However, the perioperative period is increasingly recognised as a very vulnerable time with a major impact on tumour progression. Further studies are needed to identify the underlying mechanisms and to verify their clinical relevance, especially in anaesthesia.

Naringenin improves muscle endurance via activation of the Sp1-ERRγ transcriptional axis

Skeletal muscle function declines in the aging process or disease; however, until now, skeletal muscle has remained one of the organs most undertreated with medication. In this study, naringenin (NAR) was found to build muscle endurance in wild-type mice of different ages by increasing oxidative myofiber numbers and aerobic metabolism, and it ameliorates muscle dysfunction in mdx mice. The transcription factor Sp1 was identified as a direct target of NAR and was shown to mediate the function of NAR on muscle. Moreover, the binding site of NAR on Sp1 was further validated as GLN-110. NAR enhances the binding of Sp1 to the CCCTGCCCTC sequence of the Esrrg promoter by promoting Sp1 phosphorylation, thus upregulating Esrrg expression. The identification of the Sp1-ERRγ transcriptional axis is of great significance in basic muscle research, and this function of NAR has potential implications for the improvement of muscle function and the prevention of muscle atrophy.

Evening Primrose Extract Modulates TYMS Expression via SP1 Transcription Factor in Malignant Pleural Mesothelioma.

To determine the mechanism of EPE in downregulating TYMS in MPM cancer. The TYMS mRNA expression with epithelial-to-mesenchymal transition biomarkers and nuclear factor SP1 was assessed using the GEO database in a data set of MPM patients (GSE51024). Invasive MPM cell lines were in vitro models for the investigation of TYMS expression after EPE treatment. The tyms promoter SP1 binding sequences were determined using Genomatix v 3.4 software Electrophoretic mobility shift and dual-luciferase reporter assays revealed specific SP1 motifs in the interaction of EPE and reference compounds. Chromatin immunoprecipitation and Re-ChIP were used for the co-occupancy study. In MPM patients, a positive correlation of overexpressed TYMS with mesenchymal TWIST1, FN1 and N-cadherin was observed. EPE and its major components, gallic and ellagic acid (GA and EA, respectively), downregulated TYMS in invasive MPM cells by interacting with particular SP1 motifs on the tyms promoter. The luciferase constructs confirmed the occupation of two SP1 regulatory regions critical for the promotion of TYMS expression. Both EPE and reference standards influenced SP1 translocation into the nucleus. EPE components reduced TYMS expression by occupation of SP1 motifs on the tyms promoter and reversed the EMT phenotype of invasive MPM cells. Further in-depth analysis of the molecular docking of polyphenol compounds with SP1 regulatory motifs is required.

PFKP is a prospective prognostic, diagnostic, immunological and drug sensitivity predictor across pan-cancer

Phosphofructokinase, platelet (PFKP) is a rate-limiting enzyme of glycolysis that plays a decisive role in various human physio-pathological processes. PFKP has been reported to have multiple functions in different cancer types, including lung cancer and breast cancer. However, no systematic pancancer analysis of PFKP has been performed; this type of analysis could elucidate the clinical value of PFKP in terms of diagnosis, prognosis, drug sensitivity, and immunological correlation. Systematic bioinformation analysis of PFKP was performed based on several public datasets, including The Cancer Genome Atlas (TCGA), Cancer Cell Line Encyclopedia (CCLE), Genotype-Tissue Expression Project (GTEx), and Human Protein Atlas (HPA). Prospective carcinogenesis of PFKP across cancers was estimated by expression analysis, effect on patient prognosis, diagnosis significance evaluation, and immunity regulation estimation. Then, pancancer functional enrichment of PFKP was also assessed through its effect on the signaling score and gene expression profile. Finally, upstream expression regulation of PFKP was explored by promoter DNA methylation and transcription factor (TF) prediction. Our analysis revealed that high expression of PFKP was found in most cancer types. Additionally, a high level of PFKP displayed a significant correlation with poor prognosis in patients across cancers. The diagnostic value of PFKP was performed based on its positive correlation with programmed cell death-ligand 1 (PD-L1). We also found an obvious immune-regulating effect of PFKP in most cancer types. PFKP also had a strong negative correlation with several cancer drugs. Finally, ectopic expression of PFKP may depend on DNA methylation and several predicated transcription factors, including the KLF (KLF transcription factor) and Sp (Sp transcription factor) families. This pancancer analysis revealed that a high expression level of PFKP might be a useful biomarker and predictor in most cancer types. Additionally, the performance of PFKP across cancers also suggested its meaningful role in cancer immunity regulation, even in immunotherapy and drug resistance. Overall, PFKP might be explored as an auxiliary monitor for pancancer early prognosis and diagnosis.

FRI625 Diabetic Ischemic Skeletal Muscle Injury Occurs Through Pkc-beta/sp1 Regulation Of Bag3 Expression

Abstract Disclosure: A. Mani: None. V. Lamin: None. T. Wong: None. M.V. Singh: None. A.O. Dokun: None. Peripheral arterial disease (PAD) affects more than 200 million people worldwide and is characterized by impaired blood flow to the lower extremities. Individuals with diabetes (DM) and PAD have more severe ischemic limb injuries and increased limb amputations, but the mechanisms involved are poorly understood. Following experimental PAD, C57Bl/6 mice develop limited ischemic limb injury largely due to protective effect of genes within the limb salvage QTL-1 (LSq-1) a genetic locus on chromosome 7. However, when diabetes is induced in C57Bl/6 mice they develop severe ischemic limb injuries following experimental PAD, akin to the findings in humans. Previously, we identified BAG3 as a gene within LSq-1 that is protective against ischemic limb injuries. BAG3 is upregulated in ischemic limbs from non-DM C57Bl/6 mice but poorly expressed in ischemic limbs of DM mice. The mechanism of BAG3 upregulation in ischemia is not known however the BAG3 promoter has a Specificity protein 1 (Sp1) transcription factor binding site suggesting its possible role. Moreover, how DM impairs BAG3 expression in ischemic skeletal muscles in not known. PKCβ regulates expression of transcription factors, and its phosphorylation has been implicated in the vascular pathology in DM but a role in ischemic diabetic skeletal muscle injury has not been established. Here we assessed the role of Sp1 in BAG3 upregulation in ischemic skeletal muscle cells (HSMC), we found Sp1 is upregulated in ischemic HSMCs and overexpression of Sp1 enhanced BAG3 promoter luciferase activity while knock down of Sp1 impaired BAG3 upregulation in ischemia. However, in vitro, ischemic HSMCs under DM conditions (High glucose or HG, 25mM + Palmitic acid or PA, 200µM) express lower BAG3 (fold change: Vehicle, 1.0±0.02 vs HG+PA, 0.57±0.04; n=4; p<0.05) and Sp1 (fold change: Vehicle, 1.0±0.15 vs HG+PA, 0.22±0.03; n=4; p<0.05). Overexpression of BAG3 improved survival of ischemic HSMCs in DM conditions in vitro (fold change: Vehicle, 1.0±0.02 vs HG+PA, 1.3±0.02 vs BAG3+HG+PA, 1.03±0.03; n=4-5; p<0.05) and improved extent of limb injury in vivo (Necrosis Score; DM mice without BAG3 2.67±0.29 vs DM mice + BAG3, 0.87±0.29; n=8-9; p<0.05). Additionally, under DM conditions ischemic HSMCs showed increased phosphorylation of PKCβ on the Ser661. Blocking PKCβ activation with Ruboxistaurin (Rbx), a specific inhibitor of PKCβ phosphorylation prevented the DM induced phosphorylation of PKCβ on the Ser661 (p-PKCβ/PKCβ ratio: Vehicle, 0.08±0.006 vs HG±PA, 0.19±0.03 vs Rbx+HG+PA, 0.10±0.006; n=4; p<0.05) and rescued BAG3 and Sp1 expression (BAG3, fold change: Vehicle, 1.0±0.06 vs HG±PA, 0.50±0.02 vs Rbx+HG+PA, 0.76±0.03; SP1, fold change: Vehicle, 1.0±0.02 vs HG±PA, 0.57±0.03 vs Rbx+HG+PA, 0.85±0.02; n=4; p<0.05). We conclude that impaired BAG3 expression in ischemic HSMC is mediated by impaired Sp1 expression due to increased PKCβ phosphorylation in DM. Presentation: Friday, June 16, 2023

Non-Canonical p16-SP1 Signaling in Head and Neck Cancer Potentially Affects Cell Plasticity

We have previously identified a non-canonical role for p16 in head and neck cancer (HNSCC) to repress homologous recombination (HR) via activation of a ubiquitin-mediated pathway. This was potentially via interaction with the transcription factor Sp1, however this interaction, as well as its downstream effects remain to be determined. HPV- HN5 cells forced to overexpress p16 and HPV+ UM-SCC-47 cells p16 CRISPR knockout or shRNA to Sp1 were used. Following modulation, cells were evaluated via clonogenic assay and RNA Sequencing. Additionally, a nude mouse flank model of tumors derived from UM-SCC-47 cells expressing either scrambled control or Sp1 shRNA was performed to evaluate effects on tumor growth (n = 7/group). Clonogenic assay revealed that, as expected, forced expression of p16 in HPV- cells significantly increased radiosensitivity, while CRISPR KO of p16 in HPV+ cells led to radioresistance. Preliminary results indicate a similar pattern observed when Sp1 is inhibited via shRNA. RNASeq data were examined to identify genes likely regulated by p16. Specifically, genes that were significant between p16 modulated cells (either forced expression or CRISPR KO; False Discovery Rate (FDR 1%)) with differences in expression tracking p16 (at least 1.5x higher in cells with intact p16) were evaluated via Ingenuity Pathway Analysis (IPA), with the most significant pathways repressed by p16 including: Stem cell signaling (p = 5e-4), Regulation of EMT (p = 9e-4) and WNT pathways (p = 1.6e-3). Initial results from in vivo studies indicate minimal, non-significant inhibitory effects on tumor growth following inhibition of Sp1 in UM-SCC-47. Confirmatory and radiation experiments are ongoing. Our results indicate that non-canonical functions of p16 may extend beyond direct effects on HR to modulation of aspects of cell differentiation and plasticity. If accurate, p16 may be repressing EMT, contributing to its effects on radiosensitization.

Gas7 attenuates hepatocellular carcinoma progression and chemoresistance through the PI3K/Akt signaling pathway

Growth arrest-specific gene 7 (Gas7) was involved in various cellular functions, although its specific roles and molecular mechanisms in hepatocellular carcinoma (HCC) remained unclear. So the current study was to investigate the role of Gas7 in HCC. Our findings revealed that Gas7 was downregulated in various HCC cell lines and low Gas7 expression was associated with decreased overall survival in patients with HCC. Additionally, our functional assays showed that Gas7 inhibited cell proliferation and migration, induced cell cycle arrest, apoptosis, and autophagy, and enhanced oxaliplatin sensitivity by inhibiting the PI3K/Akt signaling pathway. We also observed that transcription factorSp1 was responsible for inhibiting Gas7. These findings provide insights into the role and elucidated a potential mechanism of Gas7 in HCC progression and metastasis. It was also observed that the Sp1/Gas7/PI3K/Akt axis was critical for malignant phenotype and oxaliplatin sensitivity in HCC. Therefore, Gas7 can be considered as a prognostic predictor and therapeutic target for HCC.

Proteomics Reveals mRNA Regulation and the Action of Annexins in Thyroid Cancer.

Differentiated thyroid cancer is the most common malignancy of the endocrine system. Although most thyroid nodules are benign, given the high incidence of thyroid nodules in the population, it is important to understand the differences between benign and malignant thyroid cancer and the molecular alterations associated with malignancy to improve detection and signal potential diagnostic, prognostic, and therapeutic targets. Proteomics analysis of benign and malignant human thyroid tissue largely revealed changes indicating modifications in RNA regulation, a common cancer characteristic. In addition, changes in the immune system and cell membrane/endocytic processes were also suggested to be involved. Annexin A1 was considered a potential malignancy biomarker and, similarly to other annexins, it was found to increase in the malignant group. Furthermore, a bioinformatics approach points to the transcription factor Sp1 as being potentially involved in most of the alterations seen in the malignant thyroid nodules.

LINC00955 suppresses colorectal cancer growth by acting as a molecular scaffold of TRIM25 and Sp1 to Inhibit DNMT3B-mediated methylation of the PHIP promoter

BackgroundLong non-coding RNAs play an important role in the development of colorectal cancer (CRC), while many CRC-related lncRNAs have not yet been identified.MethodsThe relationship between the expression of LINC00955 (Long Intergenic Non-protein Coding RNA 955) and the prognosis of colorectal cancer patients was analyzed using the sequencing results of the TCGA database. LINC00955 expression levels were measured using qRT-PCR. The anti-proliferative activity of LINC00955 was evaluated using CRC cell lines in vitro and xenograft models in nude mice in vivo. The interaction of TRIM25-Sp1-DNMT3B-PHIP-CDK2 was analyzed by western blotting, protein degradation experiment, luciferase, RNA-IP, RNA pull-down assays and immunohistochemically analysis. The biological roles of LINC00955, tripartite motif containing 25 (TRIM25), Sp1 transcription factor (Sp1), DNA methyltransferase 3 beta (DNMT3B), pleckstrin homology domain interacting protein (PHIP), cyclin dependent kinase 2 (CDK2) in colorectal cancer cells were analyzed using ATP assays, Soft agar experiments and EdU assays.ResultsThe present study showed that LINC00955 is downregulated in CRC tissues, and such downregulation is associated with poor prognosis of CRC patients. We found that LINC00955 can inhibit CRC cell growth both in vitro and in vivo. Evaluation of its mechanism of action showed that LINC00955 acts as a scaffold molecule that directly promotes the binding of TRIM25 to Sp1, and promotes ubiquitination and degradation of Sp1, thereby attenuating transcription and expression of DNMT3B. DNMT3B inhibition results in hypomethylation of the PHIP promoter, in turn increasing PHIP transcription and promoting ubiquitination and degradation of CDK2, ultimately leading to G0/G1 growth arrest and inhibition of CRC cell growth.ConclusionsThese findings indicate that downregulation of LINC00955 in CRC cells promotes tumor growth through the TRIM25/Sp1/DNMT3B/PHIP/CDK2 regulatory axis, suggesting that LINC00955 may be a potential target for the therapy of CRC.

Transcriptional Stochasticity as a Key Aspect of HIV-1 Latency.

This review summarizes current advances in the role of transcriptional stochasticity in HIV-1 latency, which were possible in a large part due to the development of single-cell approaches. HIV-1 transcription proceeds in bursts of RNA production, which stem from the stochastic switching of the viral promoter between ON and OFF states. This switching is caused by random binding dynamics of transcription factors and nucleosomes to the viral promoter and occurs at several time scales from minutes to hours. Transcriptional bursts are mainly controlled by the core transcription factors TBP, SP1 and NF-κb, the chromatin status of the viral promoter and RNA polymerase II pausing. In particular, spontaneous variability in the promoter chromatin creates heterogeneity in the response to activators such as TNF-α, which is then amplified by the Tat feedback loop to generate high and low viral transcriptional states. This phenomenon is likely at the basis of the partial and stochastic response of latent T cells from HIV-1 patients to latency-reversing agents, which is a barrier for the development of shock-and-kill strategies of viral eradication. A detailed understanding of the transcriptional stochasticity of HIV-1 and the possibility to precisely model this phenomenon will be important assets to develop more effective therapeutic strategies.

CircUBXN7 promotes macrophage infiltration and renal fibrosis associated with the IGF2BP2-dependent SP1 mRNA stability in diabetic kidney disease.

Inflammatory cell infiltration is a novel hallmark of diabetic kidney disease (DKD), in part, by activated macrophages. Macrophage-to-tubular epithelial cell communication may play an important role in renal fibrosis. Circular RNAs (circRNAs) have been reported in the pathogenesis of various human diseases involving macrophages activation, including DKD. However, the exact mechanism of circRNAs in macrophage infiltration and renal fibrosis of DKD remains obscure. In our study, a novel circRNA circUBXN7 was identified in DKD patients using microarray. The function of circUBXN7 in vitro and in vivo was investigated by qRT-PCR, western blot, and immunofluorescence. Finally, a dual-luciferase reporter assay, ChIP, RNA pull-down, RNA immunoprecipitation and rescue experiments were performed to investigate the mechanism of circUBXN7. We demonstrated that the expression of circUBXN7 was significantly upregulated in the plasma of DKD patients and correlated with renal function, which might serve as an independent biomarker for DKD patients. According to investigations, ectopic expression of circUBXN7 promoted macrophage activation, EMT and fibrosis in vitro, and increased macrophage infiltration, EMT, fibrosis and proteinuria in vivo. Mechanistically, circUBXN7 was transcriptionally upregulated by transcription factor SP1 and could reciprocally promote SP1 mRNA stability and activation via directly binding to the m6A-reader IGF2BP2 in DKD. CircUBXN7 is highly expressed in DKD patients may provide the potential biomarker and therapeutic target for DKD.

PGF2alpha Inhibits 20alpha-HSD Expression by Suppressing CK1alpha-induced ERK and SP1 Activation in the Corpus Luteum of Pregnant Mice.

Prostaglandin F2α (PGF2α) is a luteolytic hormone that promotes parturition in mammals at the end of pregnancy by reducing progesterone secretion from the corpus luteum (CL). In rodents and primates, PGF2α rapidly converts progesterone to 20α-hydroxyprogesterone (20α-OHP) by promoting 20α-hydroxysteroid dehydrogenase (20α-HSD) expression. However, the specific mechanism of 20α-HSD regulation by PGF2α remains unclear. Casein Kinase 1α (CK1α) is a CK1 family member that regulates a variety of physiological functions, including reproductive development. Here, we investigated the effects of CK1α on pregnancy in female mice. Our experiments showed that CK1α is expressed in mouse CL, and its inhibition enhanced progesterone metabolism, decreased progesterone levels, and affected mouse embryo implantation. Further, CK1α mediated the effect of PGF2α on 20α-HSD in mouse luteal cells in vitro. Our results are the first to show that CK1α affects the 20α-HSD mRNA level by affecting the ERK signalling pathway to regulate the expression of the transcription factor SP1. These findings improve our understanding of PGF2α regulation of 20α-HSD.

LncRNA MACC1-AS1 associates with DDX5 to modulate MACC1 transcription in breast cancer cells

MACC1 is a master oncogene involved in multiple aspects of cancer metastasis in a broad variety of tumors. However, the molecular mechanism by which MACC1 transcription is regulated remains unclear. Here, we show that in breast cancer cells, lncRNA MACC1-AS1 serves as a cis-factor to up-regulate MACC1 transcription and this regulation increases the cell proliferation potential. Mechanistically, MACC1-AS1 forms a complex with DEAD-Box helicase 5 (DDX5) and simultaneously interacts with the distal region of the MACC1 promoter. The interaction allows its associated DDX5 to spatially contact the MACC1 core promoter and shift from MACC1-AS1 to the core promoter. Moreover, binding of DDX5 to the core promoter results in local recruitment of the transcription factor SP-1, thus enhancing MACC1 transcription. Our findings reveal a molecular mechanism by which MACC1-AS1 cis-regulates MACC1 transcription by interacting with the distal promoter region and delivering DDX5 to the core-promoter of the gene.

Inosine enhances tumor mitochondrial respiration by inducing Rag GTPases and nascent protein synthesis under nutrient starvation

Metabolic heterogeneity of tumor microenvironment (TME) is a hallmark of cancer and a big barrier to cancer treatment. Cancer cells display diverse capacities to utilize alternative carbon sources, including nucleotides, under poor nutrient circumstances. However, whether and how purine, especially inosine, regulates mitochondrial metabolism to buffer nutrient starvation has not been well-defined yet. Here, we identify the induction of 5′-nucleotidase, cytosolic II (NT5C2) gene expression promotes inosine accumulation and maintains cancer cell survival in the nutrient-poor region. Inosine elevation further induces Rag GTPases abundance and mTORC1 signaling pathway by enhancing transcription factor SP1 level in the starved tumor. Besides, inosine supplementary stimulates the synthesis of nascent TCA cycle enzymes, including citrate synthesis (CS) and aconitase 1 (ACO1), to further enhance oxidative phosphorylation of breast cancer cells under glucose starvation, leading to the accumulation of iso-citric acid. Inhibition of the CS activity or knockdown of ACO1 blocks the rescue effect of inosine on cancer survival under starvation. Collectively, our finding highlights the vital signal role of inosine linking mitochondrial respiration and buffering starvation, beyond serving as direct energy carriers or building blocks for genetic code in TME, shedding light on future cancer treatment by targeting inosine metabolism.

Molecular mechanism of an aspirin compound for alleviation of osteoporosis using nerwork pharmacology and molecular docking

The aspirin compound (AC) is commonly found to have a wide range ofpharmacological activities. This study aimed to investigate the underlying mechanism ofthe anti-osteoporotic (anti-OP) activity of AC using network pharmacology and moleculardocking approaches. First, AC targets were identified using the GeneCards database, andsecond, OP-related targets were mined using a combination of the GeneCards andDisGeNet databases. The intersection targets from the Genecards, AC, and OP databaseswere considered candidate targets and were utilized to calculate protein-protein interactionsbetween targets. We discovered a C4A intersection target in the Genecards, AC, and OPdatabases. This is useful for molecular binding. In addition, we obtained 11 additionalprospective targets that may be used to attach the AC molecule to these targets. At theintersection region of the AC and OP target groups are the target genes HLA-DQA1, HLADQB1, RPL31, SATB2, SP1, and WNT1. And at the intersection region of the GeneCardsand OP databases, we discovered the anti-OP target genes CTSK, PDIA2, RARG, andTBC1D8. They are crucial binding targets that interact with other protein targets.According to the protein-protein interaction network, C4A showed the highest bindingcapacity with other proteins. The gene ontology (GO) analysis performed in this workfound the 10 biological processes, 10 cellular components, 9 molecular activities, and 13biological pathways. Furthermore, C4A and 10 candidate targets are associated withhomologous genes mainly involved in the signaling pathways of the Kyoto Encyclopediaof Genomics and Genomics (KEGG). The AC molecule was found to be highly bound to11 target candidates. This study identified candidate targets for AC to alleviate OP usingthe search for protein-protein interactions and the associated signaling pathways of thetargets to endorse AC against OP. This may help us understand the mechanism of action ofAC during OP treatment.