Sp1 Target Research Articles

Ginkgo Biloba Bioactive Phytochemicals against Age-Related Diseases: Evidence from a Stepwise, High-Throughput Research Platform.

The seeds of ginkgo biloba L (GB) have been widely used worldwide. This study investigated the bioefficacies of whole GB seed powder (WGP) retaining the full nutrients of ginkgo against aging, atherosclerosis, and fatigue. The experimental results indicated that WGP lowered brain monoamine oxidase and serum malondialdehyde levels, enhanced thymus/spleen indexes, and improved learning ability, and delayed aging in senescent mice. WGP regulated lipid levels and prevented atherosclerosis by reducing triglycerides, lowering low-density lipoprotein cholesterol, increasing high-density lipoprotein cholesterol, and decreasing the atherosclerosis index. WGP improved exercise performance by reducing blood lactate accumulation and extending exhaustive swimming and climbing times, improved energy storage by increasing muscle/liver glycogen levels, and relieved physical fatigue. Network pharmacology analysis revealed 270 potential targets of WGP that play roles in cellular pathways related to inflammation inhibition, metabolism regulation, and anti-cellular senescence, etc. Protein-protein interaction analysis identified 10 hub genes, including FOS, ESR1, MAPK8, and SP1 targets. Molecular docking and molecular dynamics simulations showed that the bioactive compounds of WGP bound well to the targets. This study suggests that WGP exerts prominent health-promoting effects through multiple components, targets, and pathways.

PSAT1 Promotes Metastasis via p-AKT/SP1/ITGA2 Axis in Estrogen Receptor-Negative Breast Cancer Cell.

Accumulating evidence indicates that PSAT1 not only reprogrammed metabolic function but also exhibits "moonlighting" functions in promoting tumor malignancy. However, the underlying molecular mechanisms of PSAT1 promoting ER-negative breast cancer cell migration need further investigation. Briefly, the PSAT1 and ITGA2 expression in cells and tissues was detected using qRT-PCR, immunofluorescence staining and western blot assay. The effect of PSAT1 and ITGA2 was verified both in vitro and in vivo. RNA-seq analysis explored a series of differently expressed genes. The regulation between SP1 and ITGA2 was investigated by ChIP analysis. We reported PSAT1 was highly expressed in ER-breast cancer tissues and tumor cells and positively correlated with metastasis. Moreover, RNA-seq analysis explored a series of differently expressed genes, including ITGA2, in PSAT1 overexpressed cells. Mechanistically, PSAT1 facilitated breast cancer metastasis via the p-AKT/SP1/ITGA2 axis. We further elucidated that PSAT1 promoted the entry of SP1 into the nucleus through the upregulation of p-AKT and confirmed ITGA2 is a target of SP1. In addition, enhanced cell migration was remarkably reversed by ITGA2 depletion or p-AKT inhibitor treatment. This study clarified the mechanism of PSAT1 in promoting ER-negative breast cancer metastasis, which may provide mechanistic clues for attenuating breast cancer metastasis.

Tolfenamic Acid Derivatives: A New Class of Transcriptional Modulators with Potential Therapeutic Applications for Alzheimer's Disease and Related Disorders.

The field of Alzheimer's disease (AD) has witnessed recent breakthroughs in the development of disease-modifying biologics and diagnostic markers. While immunotherapeutic interventions have provided much-awaited solutions, nucleic acid-based tools represent other avenues of intervention; however, these approaches are costly and invasive, and they have serious side effects. Previously, we have shown in AD animal models that tolfenamic acid (TA) can lower the expression of AD-related genes and their products and subsequently reduce pathological burden and improve cognition. Using TA as a scaffold and the zinc finger domain of SP1 as a pharmacophore, we developed safer and more potent brain-penetrating analogs that interfere with sequence-specific DNA binding at transcription start sites and predominantly modulate the expression of SP1 target genes. More importantly, the proteome of treated cells displayed ~75% of the downregulated products as SP1 targets. Specific levels of SP1-driven genes and AD biomarkers such as amyloid precursor protein (APP) and Tau proteins were also decreased as part of this targeted systemic response. These small molecules, therefore, offer a viable alternative to achieving desired therapeutic outcomes by interfering with both amyloid and Tau pathways with limited off-target systemic changes.

The non-cell-autonomous function of ID1 promotes AML progression via ANGPTL7 from the microenvironment

AbstractThe bone marrow microenvironment (BMM) can regulate leukemia stem cells (LSCs) via secreted factors. Increasing evidence suggests that dissecting the mechanisms by which the BMM maintains LSCs may lead to the development of effective therapies for the eradication of leukemia. Inhibitor of DNA binding 1 (ID1), a key transcriptional regulator in LSCs, previously identified by us, controls cytokine production in the BMM, but the role of ID1 in acute myeloid leukemia (AML) BMM remains obscure. Here, we report that ID1 is highly expressed in the BMM of patients with AML, especially in BM mesenchymal stem cells, and that the high expression of ID1 in the AML BMM is induced by BMP6, secreted from AML cells. Knocking out ID1 in mesenchymal cells significantly suppresses the proliferation of cocultured AML cells. Loss of Id1 in the BMM results in impaired AML progression in AML mouse models. Mechanistically, we found that Id1 deficiency significantly reduces SP1 protein levels in mesenchymal cells cocultured with AML cells. Using ID1-interactome analysis, we found that ID1 interacts with RNF4, an E3 ubiquitin ligase, and causes a decrease in SP1 ubiquitination. Disrupting the ID1-RNF4 interaction via truncation in mesenchymal cells significantly reduces SP1 protein levels and delays AML cell proliferation. We identify that the target of Sp1, Angptl7, is the primary differentially expression protein factor in Id1-deficient BM supernatant fluid to regulate AML progression in mice. Our study highlights the critical role of ID1 in the AML BMM and aids the development of therapeutic strategies for AML.

SP1 transcriptionally regulates UBE2N expression to promote lung adenocarcinoma progression

Lung adenocarcinoma (LUAD) is the main cause of cancer-related death worldwide. Understanding the mechanisms of LUAD progression may provide insights into targeted therapy approaches for this malignancy. Ubiquitin-conjugating enzyme 2 N (UBE2N) has been demonstrated to play key roles in the progression of various cancers. However, the functions and mechanisms underlying UBE2N expression in LUAD are still unclear. In this study, we found that UBE2N is highly expressed in LUAD and patients with high UBE2N expression in their tumors have poor clinical outcomes. Moreover, we showed that UBE2N interference significantly inhibited LUAD progression in vitro and in vivo. At the molecular level, we demonstrated that the UBE2N is a bona fide target of transcription factor SP1. SP1 directly bound to the promoter of UBE2N and upregulated its expression in LUAD cells, which in turn contributed to the progression of LUAD. Furthermore, we found that there is a strong positive correlation between the expression of SP1 and UBE2N in LUAD samples. Importantly, LUAD patients with concomitantly high expression of SP1 and UBE2N were significantly associated with poor clinical outcomes. In conclusion, our study demonstrated that the SP1-UBE2N signaling axis might play a key role in the malignant progression of LUAD, which provides new targets and strategies for the treatment of LUAD.

DDB1 and CUL4 Associated Factor 7 (DCAF7) Is Essential for Hematopoiesis

Mutations in DDB1 And CUL4 Associated Factor 7 (DCAF7) have been detected in a subset of patients with Myeloid Leukemia in Down syndrome. DCAF7 is a highly conserved WD40 domain protein with 100% homology among vertebrates and is a prominent binding partner of DYRK1A, a kinase located on chromosome 21. Analysis of the DepMap database revealed that hematopoietic cell lines are highly dependent on DCAF7 compared to cell lines from other tumors. However, the function of DCAF7 during normal hematopoiesis is currently unknown. Thus, we aimed to study its function in hematopoietic cell lines and in a conditional knockout mouse model. We first deleted DCAF7 from a panel of hematopoietic cell lines by CRISPR/Cas9 editing and observed its absence led to cell cycle arrest and decreased proliferation. Rescue experiments in which a CRISPR resistant DCAF7 allele was expressed in the targeted clones restored proliferation and cell cycling. A comparison of RNA-seq data between parental HEL cells and those without DCAF7 showed decreased expression of genes involved in differentiation, TNF signaling and the IFN pathway, indicating that DCAF7 is important for cell differentiation. Next, we created a Dcaf7 conditionally targeted mouse strain (Dcaf7F/F Mx-1 Cre) and assessed its role in hematopoiesis in vivo. Following Cre induction by pIpC, we observed a decrease in white blood cells, hemoglobin and platelet counts in KO mice. Analysis of the bone marrow showed an accumulation of LT-HSCs and multipotent progenitors. In addition, we observed a defect in the generation of B-cells, reminiscent of the phenotype observed upon Dyr1ka deletion. We then tested the recovery of Dcaf7 KO hematopoietic cells after different types of stress, which included ex-vivo culture, transplantation, and myelosuppression. Dcaf7 deficient HSCs showed defective expansion in PVA-containing media and poor differentiation in single cell colony assays in methylcellulose. In non-competitive transplants, KO cells reconstituted hematopoiesis although the number of mature myeloid and lymphoid cells was dramatically decreased. In competitive transplants, Dcaf7 KO cells were outcompeted by wild-type cells. Lastly, upon myelosuppression with 5-FU, Dcaf7 deficient mice were not able to recover and died acutely. Overall, these results indicate that DCAF7 plays a critical role in HSCs during homeostasis and regeneration. To uncover the mechanisms by which DCAF7 contributes to hematopoiesis, we performed IP-MS using tagged DCAF7 as bait in a hematopoietic cell line. In addition to DYRK1A, we found that DCAF7 interacts with multiple components of the polycomb repressive complex1 (PRC1), specifically the non-canonical PRC1.5 complex, which has been previously implicated in gene activation and transcription. We confirmed that DCAF7 engages in the PRC1.5 complex by glycerol gradient centrifugation. Upon DCAF7 absence the size the PRC1 complex shifts towards a lower molecular weight, indicating that DCAF7 is a core subunit of the complex. We then performed RNASeq analysis in sorted LT-HSCs (Lin-cKit+Sca1+CD48-CD150+) and found that 70% of the differentially expressed genes were downregulated in KO cells. These downregulated genes were associated with diminished activation of GATA1, GATA2, RUNX1 and SP1 target genes, in agreement with the functional role of the PRC1.5 complex in gene activation and cell differentiation. Together our results reveal that DCAF7 regulates hematopoiesis by participating in transcriptional regulatory complexes, and we predict that DCAF7 mutations contribute to leukemia by cooperating with DYRK1A and altering the activity of the PRC1 complex.

Regulation of alternative polyadenylation by the C2H2-zinc-finger protein Sp1

Alternative polyadenylation (APA) enhances gene regulatory potential by increasing the diversity of mRNA transcripts. 3' UTR shortening through APA correlates with enhanced cellular proliferation and is a widespread phenomenon in tumor cells. Here, we show that the ubiquitously expressed transcription factor Sp1 binds RNA invivo and is a common repressor of distal poly(A) site usage. RNA sequencing identified 2,344 genes (36% of the total mapped mRNA transcripts) with lengthened 3' UTRs upon Sp1 depletion. Sp1 preferentially binds the 3' UTRs of such lengthened transcripts and inhibits cleavage at distal sites by interacting with the subunits of the core cleavage and polyadenylation (CPA) machinery. The 3' UTR lengths of Sp1 target genes in breast cancer patient RNA-seq data correlate with Sp1 expression levels, implicating Sp1-mediated APA regulation in modulating tumorigenic properties. Taken together, our findings provide insights into the mechanism for dynamic APA regulation by unraveling a previously unknown function of the DNA-binding transcription factor Sp1.

The WNK1 kinase regulates the stability of transcription factors during wound healing of human corneal epithelial cells

Due to its superficial anatomical localization, the cornea is continuously subjected to injuries. Damages to the corneal epithelium trigger important changes in the composition of the extracellular matrix to which the basal human corneal epithelial cells (hCECs) attach. These changes are perceived by membrane-bound integrins and ultimately lead to re-epithelialization of the injured epithelium through intracellular signalin. Among the many downstream targets of the integrin-activated signaling pathways, WNK1 is the kinase whose activity is the most strongly increased during corneal wound healing. We previously demonstrated that pharmacological inhibition of WNK1 prevents proper closure of wounded human tissue-engineered cornea in vitro. In the present study, we investigated the molecular mechanisms by which WNK1 contributes to corneal wound healing. By exploiting transcription factors microarrays, electrophoretic mobility-shift assay, and gene profiling analyses, we demonstrated that the DNA binding properties and expression of numerous transcription factors (TFs), including the well-known, ubiquitous TFs specific protein 1 (Sp1) and activator protein 1 (AP1), were reduced in hCECs upon WNK1 inhibition by WNK463. This process appears to be mediated at least in part by alteration in both the ubiquitination and glycosylation status of these TFs. These changes in TFs activity and expression impacted the transcription of several genes, including that encoding the α5 integrin subunit, a well-known target of both Sp1 and AP1. Gene profiling revealed that only a moderate number of genes in hCECs had their level of expression significantly altered in response to WNK463 exposition. Interestingly, analysis of the microarray data for these deregulated genes using the ingenuity pathway analysis software predicted that hCECs would stop migrating and proliferating but differentiate more when they are grown in the presence of the WNK1 inhibitor. These results demonstrate that WNK1 plays a critical function by orienting hCECs into the appropriate biological response during the process of corneal wound healing.

MiR-4310 induced by SP1 targets PTEN to promote glioma progression

BackgroundmiRNAs have been reported to be involved in multiple biological processes of gliomas. Here, we aimed to analyze miR-4310 and its correlation genes involved in the progression of human glioma.MethodsmiR-4310 expression levels were examined in glioma and non-tumor brain (NB) tissues. The molecular mechanisms of miR-4310 expression and its effects on cell proliferation, migration, and invasion were explored using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide, Transwell chamber, Boyden chamber, and western blot analyses, as well as its effect on tumorigenesis was explored in vivo in nude mice. The relationships between miR-4310, SP1, phosphatase, and tensin homolog (PTEN) were explored using chromatin immunoprecipitation, agarose gel electrophoresis, electrophoresis mobility shift, and dual-luciferase reporter gene assays.ResultsmiR-4310 expression was upregulated in glioma tissues compared to that in NB tissues. Overexpressed miR-4310 promoted glioma cell proliferation, migration, and invasion in vitro, as well as tumorigenesis in vivo. The inhibition of miR-4310 expression was sufficient to reverse these results. Mechanistic analyses revealed that miR-4310 promoted glioma progression through the PI3K/AKT pathway by targeting PTEN. Additionally, SP1 induced the expression of miR-4310 by binding to its promoter region.ConclusionmiR-4310 promotes the progression of glioma by targeting PTEN and activating the PI3K/AKT pathway; meanwhile, the expression of miR-4310 was induced by SP1.

In vivo analysis of the evolutionary conserved BTD-box domain of Sp1 and Btd during Drosophila development

The Sp family of transcription factors plays important functions during development and disease. An evolutionary conserved role for some Sp family members is the control of limb development. The family is characterized by the presence of three C2H2-type zinc fingers and an adjacent 10 aa region with an unknown function called the Buttonhead (BTD) box. The presence of this BTD-box in all Sp family members identified from arthropods to vertebrates, suggests that it plays an essential role during development. However, despite its conservation, the in vivo function of the BTD-box has never been studied. In this work, we have generated specific BTD-box deletion alleles for the Drosophila Sp family members Sp1 and buttonhead (btd) using gene editing tools and analyzed its role during development. Unexpectedly, btd and Sp1 mutant alleles that lack the BTD-box are viable and have almost normal appendages. However, in a sensitized background the requirement of this domain to fully regulate some of Sp1 and Btd target genes is revealed. Furthermore, we have also identified a novel Sp1 role promoting leg vs antenna identity through the repression of spineless (ss) expression in the leg, a function that also depends on the Sp1 BTD-box.

A frameshift variant in specificity protein 1 triggers superactivation of Sp1-mediated transcription in familial bone marrow failure

Inherited bone marrow failure (BMF) syndromes are a heterogeneous group of diseases characterized by defective hematopoiesis and often predisposing to myelodysplastic syndrome (MDS) and acute myelogenous leukemia. We have studied a large family consisting of several affected individuals with hematologic abnormalities, including one family member who died of acute leukemia. By whole-exome sequencing, we identified a novel frameshift variant in the ubiquitously expressed transcription factor specificity protein 1 (SP1). This heterozygous variant (c.1995delA) truncates the canonical Sp1 molecule in the highly conserved C-terminal DNA-binding zinc finger domains. Transcriptomic analysis and gene promoter characterization in patients' blood revealed a hypermorphic effect of this Sp1 variant, triggering superactivation of Sp1-mediated transcription and driving significant up-regulation of Sp1 target genes. This familial genetic study indicates a central role for Sp1 in causing autosomal dominant transmission of BMF, thereby confirming its critical role in hematopoiesis in humans.

Zinc Finger Protein St18 Protects against Septic Death by Inhibiting VEGF-A from Macrophages

Zinc finger protein St18 was initially reported as candidate tumor suppressor gene, and also suggested that fibroblast St18 positively regulates NF-κB activation. Despite the pleiotropic functions of St18, little is known about its roles in macrophages. Here, we report that myeloid St18 is a potent inhibitor of VEGF-A. Mice lacking St18 in myeloid lineages exhibit increased retinal vasculature with enhanced serum VEGF-A concentrations. Despite the normal activation of NF-κB target genes, these mice are highly susceptible to LPS-induced shock, polymicrobial sepsis, and experimental colitis, accompanied by enhanced vascular and intestinal leakage. Pharmacological inhibition of VEGF signaling rescued the high mortality rate of myeloid-specific St18-deficient mice in response to inflammation. Mechanistically, St18 directly binds to Sp1 and attenuates its activity, leading to the suppression of Sp1 target gene VEGF-A. Using mouse genetic and pharmacological models, we reveal myeloid St18 as a critical septic death protector.

Klotho is regulated by transcription factor Sp1 in renal tubular epithelial cells

BackgroundKlotho is a multifunctional protein, which exists both in a membrane bound and a soluble form. In renal tubules, Klotho is involved in cell senescence, anti-oxidant response, and renal fibrosis, thus regulation of its expression is critical to understand its roles in renal diseases. Indeed, reduced expression was observed in various renal disease. However, the mechanisms underlying transcriptional regulation of the human klotho gene (KL) largely remain unknown.ResultsHere we demonstrated that the Klotho expression in human renal tubular epithelial cells (RTECs) was enhanced by overexpression of the transcription factor Sp1. On the contrary, Klotho expression was decreased by Sp1 knockdown. Besides, increased expression of Sp1 alleviated TGF-β1-induced fibrosis in HK-2 cells by inducing Klotho expression. Luciferase reporter assays and chromatin immunoprecipitation assays further identified the binding site of Sp1 was located in − 394 to − 289 nt of the KL promoter, which was further confirmed by mutation analysis.ConclusionsThese data demonstrate that KL is a transcriptional target of Sp1 and TGF-β1-induced fibrosis was alleviated by Sp1 in human RTECs by directly modulating Klotho expression, which help to further understand the transcriptional regulation of Klotho in renal disease models.

High Expression Level of SP1, CSF1R, and PAK1 Correlates with Sensitivity of Leukemia Cells to the Antibiotic Mithramycin

Acute myeloid leukemia (AML) is a genetically heterogeneous group of oncological diseases of the hematopoietic system, which are extremely difficult to treat. The development of new targeted drugs (Hylteritinib, Venetoclax) significantly improved the survival of patients, but resistance, as well as cytotoxic anti-leukemia drugs, often occurs. The search for new molecular targets for the development of effective approaches for the treatment of AML is very urgent. In blast cells of patients with AML, mutations, chromosomal rearrangements, and increased expression of a number of non-mutant genes, including transcription factor genes, are detected. The transcription factor Sp 1 binds to GC-rich regions of regulatory regions of various genes and thus controls their expression. Sp1 targets include genes responsible for proliferation, cell cycle regulation, and differentiation. In many malignant diseases, a high level of Sp1 gene expression is associated with an unfavorable prognosis, therefore, Sp1 is considered as a promising therapeutic target for cancer. In this paper, we estimated the expression levels of Sp1 in various malignant tissues. Increased Sp1 expression was detected in samples obtained from patients with AML, acute lymphoblastic leukemia, Ewing sarcoma, ovarian and kidney cancer. It is also shown that Sp1 expression correlates with the expression of genes encoding cytokine receptors and growth factors (CSF1R and IL6R), intracellular kinases (CSK, SYK, PAK1, ILK, JAK2), and transcription factor LMO2. The correlation between expression levels of Sp1 and CSF1R, SYK, Jak2 and LMO2 is also characteristic of transplanted human leukemia cells. We measured expression levels of Sp1, CSF1R, ILK, PAK1 in the cells of three transplantable lines of human leukemia and found increased levels of expression of these genes in Kasumi-1 cells. In addition, we showed that Kasumi-1 cells are most sensitive to Mitramycin, a drug that displaces Sp1 from its targets with DNA. Our data indicate the need to identify AML cells that are most sensitive to inhibition of Sp1 activity in order to assess the possibility of suppressing its activity in vivo.

Lung myofibroblast transition and fibrosis is regulated by circ0044226.

Idiopathic pulmonary fibrosis (IPF) is a life-threatening progressive disease characterized by aberrant fibroblast activation. This study aims to explore the role of the circ0044226 on fibroblast-to-myofibroblast transition (FMT). Bleomycin and TGF-β1 were respectively used to induce the IPF mice model and human lung fibroblasts to myofibroblast differentiation. The mRNA and protein levels were examined by qRT-PCR and western blot. Localization of α-SMA was evaluated by immunofluorescence staining. Cell viability and proliferation were evaluated by CCK8 and EDU test. Dual-luciferase reporter assay was used to analyze the interaction between miR-7 and circ0044226 or sp1. Fluorescence in situ hybridization (FISH) assay was used for the identification of sub-location of circ0044226 and miR-7 in cells. The IPF model mice received intratracheal injection of AAV-sh-NC and AAV-sh- circ0044226, and lung fibrosis was detected by HE staining, Masson staining and immunohistochemistry assay. The circ0044226 was upregulated while miR-7 was downregulated in IPF mice model and FMT-derived myofibroblasts. miR-7 was a target of circ0044226 and sp1 was a target of miR-7. circ0044226 was distributed mostly in the cytoplasm and functioned as a miR-7 sponge to positively regulate the expression of sp1. Intervention of circ0044226 could ameliorate FMT and suppress fibroblast viability and proliferation by functioning as an endogenous miR-7 sponge. Circ0044226 knockdown alleviates fibroblast proliferation and FMT by functioning as a competing endogenous RNA, which may represent a promising therapy for pulmonary fibrosis.

Synergistic targeting of Sp1 in myeloma cells with hyperthermia plus proteasome inhibitors

Multiple myeloma (MM) and extramedullary plasmacytoma still remain incurable despite recent advances in the treatment of MM. MM-initiating cells or MM progenitors are considered to contribute to disease relapse through their drug-resistant nature. We recently developed novel superparamagnetic iron oxide nanoparticles which selectively accumulate in extramedullary plasmacytoma and to kill their progenitors by heat generated with magnetic resonance (Theranostics, 2013). Therefore, superparamagnetic iron oxide nanoparticles potentially achieve what is called ''theranostics'', a combination of tumor imaging and targeting treatment for extramedullary tumors.

The LIM protein Ajuba/SP1 complex forms a feed forward loop to induce SP1 target genes and promote pancreatic cancer cell proliferation

BackgroundThe aim of this study is to explore the molecular mechanism of the LIM protein Ajuba and the transcription factor SP1 in the pathogenesis and progression of PDAC. Ajuba is a newly defined transcriptional co-regulator and plays important role in various cancer development, while SP1 is a classic transcription factor, and is closely related with a variety of gene expression and cancer development including PDAC.MethodsThe expression of Ajuba and SP1 in PDAC tissues was detected by immunohistochemistry (IHC), and the correlation between expression level and clinical prognosis of Ajuba and SP1 was extensively analyzed using online tools. The interaction between Ajuba and SP1 was examined by co-immunoprecipitation (co-IP) and GST-pulldown assays. Stable cell lines were established via lentiviral infection, and was examined by qRT-PCR and western blot assays. The effects of Ajuba/SP1 on PDAC cell proliferation were examined using CCK8 and colony formation assays. Luciferase reporter and chromatin immunoprecipitation (ChIP) assays were employed to examine the transcription activity.ResultsThe expression level (protein and mRNA) of Ajuba and SP1 was elevated in PDAC tissues and was positively correlated; patients with high Ajuba and SP1 expression had a poor prognosis. Mechanistically, Ajuba binds to the C-terminus of SP1 and functions as a co-activator to enhance SP1 gene expression and promote cell proliferation; the promoter of Ajuba contains functional SP1 responsive elements and Ajuba itself is a target gene of SP1.ConclusionAjuba functions as a co-activator of SP1 to induce its target gene, and that Ajuba itself is a target genes of SP1. Ajuba/SP1 complex could form a feed forward loop to drive SP1 target gene transcription and promote cell proliferation of pancreatic cancer cells. Ajuba and SP1 might be biomarkers for PDAC diagnostics, prognosis and targets for new therapeutics.

Sp1 Suppresses miR-3178 to Promote the Metastasis Invasion Cascade via Upregulation of TRIOBP

Specificity protein (Sp1) plays an important role in invasion-metastasis cascade. Sp1 regulation on protein coding genes has been extensively investigated; however, little is known about its regulation on protein non-coding genes. In this study, miR-3178 is reported as a novel target of Sp1 in multiple cancer cell models. Sp1 functions as its transcriptional suppressor as evidenced by luciferase reporter and chromatin immunoprecipitation (ChIP) assays. In line with the pro-metastatic role of Sp1, miR-3178 exerts anti-metastasis function. Overexpression of miR-3178 inhibits both migration and invasion of highly metastatic prostate, lung, and breast cancer cells whereas antagonizing miR-3178 promotes those events in their lowly metastatic counterparts. The in vivo study demonstrates that miR-3178 suppresses the tail vein inoculated prostate cancer cells to form colonies in lung, lymph node, and liver of BALB/c nude mice. miR-3178 directly targets the 3′ UTR of TRIOBP-1 and TRIOBP-5, two isoforms of TRIOBP expressed in prostate, lung, and breast cancer cells. Overexpression of TRIOBP-1 could rescue miR-3178 inhibition on cell migration and invasion. Collectively, our findings reveal the regulatory axis of Sp1/miR-3178/TRIOBP in metastasis cascade. Our results suggest miR-3178 as a promising application to suppress metastasis in Sp1-overexpressed cancers.

Discovery of Novel Human Gene Regulatory Modules from Gene Co-expression and Promoter Motif Analysis

Deciphering gene regulatory networks requires identification of gene expression modules. We describe a novel bottom-up approach to identify gene modules regulated by cis-regulatory motifs from a human gene co-expression network. Target genes of a cis-regulatory motif were identified from the network via the motif’s enrichment or biased distribution towards transcription start sites in the promoters of co-expressed genes. A gene sub-network containing the target genes was extracted and used to derive gene modules. The analysis revealed known and novel gene modules regulated by the NF-Y motif. The binding of NF-Y proteins to these modules’ gene promoters were verified using ENCODE ChIP-Seq data. The analyses also identified 8,048 Sp1 motif target genes, interestingly many of which were not detected by ENCODE ChIP-Seq. These target genes assemble into house-keeping, tissues-specific developmental, and immune response modules. Integration of Sp1 modules with genomic and epigenomic data indicates epigenetic control of Sp1 targets’ expression in a cell/tissue specific manner. Finally, known and novel target genes and modules regulated by the YY1, RFX1, IRF1, and 34 other motifs were also identified. The study described here provides a valuable resource to understand transcriptional regulation of various human developmental, disease, or immunity pathways.

DNA methyltransferase 1 may be a therapy target for attenuating diabetic nephropathy and podocyte injury

The contribution of DNA methylation to diabetic nephropathy, especially the effect on podocyte integrity, is not clarified. Here we found that albuminuria in a db/db mouse model was markedly attenuated after treatment with a DNA methylation inhibitor. This was accompanied by alleviation of glomerular hypertrophy, mesangial matrix expansion, and podocyte injury. The expression of DNA methyltransferase 1 (Dnmt1), nuclear factor Sp1, and nuclear factor kappa B (NFκB)-p65 markedly increased in podocytes invivo and invitro under the diabetic state. The increased expression of Dnmt1 was attenuated after treatment with 5-azacytidine or 5-aza-2'-deoxycytidine or Dnmt1 knockdown, accompanied by restored decreased podocyte slit diaphragm proteins resulting from hypermethylation and improved podocyte motility. Further studies found that increased Sp1 and NFκB-p65 interacted in the nucleus of podocytes incubated with high glucose, and Sp1 bound to the Dnmt1 promoter region. The involvement of the Sp1/NFκB-p65 complex in Dnmt1 regulation was confirmed by the observation that Sp1 knockdown using mithramycin A or siRNA decreased Dnmt1 protein levels. The luciferase reporter assay further indicated that Dnmt1 was a direct target of Sp1. Thus, inhibition of DNA methylation may be a new therapeutic avenue for treating diabetic nephropathy. Hence, the Sp1/NFκB p65-Dnmt1 pathway may be exploited as a therapeutic target for protecting against podocyte injury in diabetic nephropathy.