USF2 promotes autophagy and proliferation in chronic lymphocytic leukemia by inhibiting STUB1-induced NFAT5 ubiquitination.

Chronic lymphocytic leukemia (CLL) mainly affects the health of older adults and is difficult to cure. Upstream stimulatory factor 2 (USF2) has been implicated in several diseases and conditions including cancers. However, the effect of USF2 on CLL has not been elucidated. To investigate the effect of USP2 on proliferation and autophagy of CLL, and to explore the underlying mechanism. The mRNA of USF2 and STIP1 homology and U-Box containing protein 1 (STUB1) was analyzed using qRT-PCR. Western blots were used to evaluate the expression level of USF2, LC3II, Beclin-1, P62, STUB1, and NFAT5. The cell proliferation was evaluated using CCK-8 and EdU assays. The cell apoptosis was evaluated using flow cytometry. Indirect fluorescent assay (IFA) was performed to analyze LC3 signal. Nuclear factor of activated T-cells 5 (NFAT5) ubiquitination was detected using immunoprecipitation (IP) assay. The CLL progression was evaluated in xenotransplantation model of nude mice. USF2 was highly expressed in CLL tissues and cell lines. USF2 knockdown suppressed the cell viability and EdU incorporation, while promoting cell apoptosis. Meanwhile, USF2 knockdown reduced the level of LC3II and Beclin-1, but increased P62, illustrating USF2 knockdown inhibiting autophagy. USF2 induced NFAT5 ubiquitination and promoted NFAT5 protein level via repressing STUB1. The downregulation of USF2 weakened CLL progression in xenotransplantation model of nude mice. CLL survival and autophagy was dependent on highly expressed USF2 which promoted the expression and ubiquitination of NFAT5 through inhibiting the transcription of STUB1, which makes USF2 a promising therapeutic candidate for CLL treatment.

Usf2 Deficiency Promotes Autophagy to Alleviate Cerebral Ischemia-Reperfusion Injury Through Suppressing YTHDF1-m6A-Mediated Cdc25A Translation.

Autophagy has been involved in protection of ischemia/reperfusion (I/R)-induced injury in many tissues including the brain. The upstream stimulatory factor 2 (Usf2) was proposed as a regulator in aging and degenerative brain diseases; however, the its role in autophagy during cerebral I/R injury remains unclear. Here, the middle cerebral artery occlusion (MCAO) operation was applied to establish an I/R mouse model. We showed that Usf2 was significantly upregulated in I/R-injured brain, accompanied by decreased levels of autophagy. Then, oxygen-glucose deprivation/recovery (OGD/R) treatment was used to establish a cellular I/R model in HT22 neurons, and lentiviral interference vector against Usf2 (LV-sh-Usf2) was used to infect the neurons. Our results showed that Usf2 was significantly upregulated in OGD/R-treated HT22 neurons that displayed an increased level in cell apoptosis and decreased levels in cell viability and autophagy, and interference of Usf2 largely rescued the effects of OGD/R on cell viability, apoptosis, and autophagy, suggesting an important role of Usf2 in neuron autophagy. In the mechanism exploration, we found that, as a transcription factor, Usf2 bound to the promoter of YTHDF1, a famous reader of N6-Methyladenosine (m6A), also induced by OGD/R, and promoted its transcription. Overexpression of YTHDF1 was able to reverse the improvement of Usf2 interference on viability and autophagy of HT22 neurons. Moreover, YTHDF1 suppressed autophagy to induce HT22 cell apoptosis through increasing m6A-mediated stability of Cdc25A, a newly identified autophagy inhibitor. Finally, we demonstrated that interference of Usf2 markedly improved autophagy and alleviated I/R-induced injury in MCAO mice.

Long non-coding RNA X-Inactive Specific Transcript (XIST) interacting with USF2 promotes osteogenic differentiation of periodontal ligament stem cells through regulation of WDR72 transcription.

BACKGROUND: Periodontal ligament stem cells (PDLSCs) are the most potential cells in periodontal tissue regeneration and bone tissue regeneration. Our prior work had revealed that WD repeat-containing protein 72 (WDR72) was crucial for osteogenic differentiation of PDLSCs. Here, we further elucidated its underlying mechanism in PDLSC osteogenic differentiation. METHODS: Human PDLSCs, isolated and identified by flow cytometry, were prepared for osteogenic differentiation induction. Levels of WDR72, long non-coding RNA X-Inactive Specific Transcript (XIST), upstream stimulatory factor 2 (USF2), and osteogenic marker genes (Runx2, Osteocalcin, and Collagen I) in human PDLSCs and clinical specimens were detected by RT-qPCR. Protein expressions of WDR72, Runx2, Osteocalcin, and Colla1 were tested by Western blot. The interactions among the molecules were verified by RIP, RNA pull-down, ChIP, and luciferase reporter assays. Osteogenic differentiation was evaluated by alkaline phosphatase (ALP) and alizarin red staining (ARS). RESULTS: WDR72 was decreased in periodontal tissues of periodontitis patients, and overexpression reversed TNF-α-mediated suppressive effects on PDLSC osteogenic differentiation. Mechanically, XIST recruited the enrichment of USF2 to the WDR72 promoter region, thereby positively regulating WDR72. WDR72 silencing overturned XIST-mediated biological effects in PDLSCs. CONCLUSION: WDR72, regulated by the XIST/USF2 axis, enhances osteogenic differentiation of PDLSCs, implying a novel strategy for alleviating periodontitis.

Upstream Stimulatory Factors Regulate HIV-1 Latency and Are Required for Robust T Cell Activation.

HIV-1 provirus expression is controlled by signaling pathways that are responsive to T cell receptor engagement, including those involving Ras and downstream protein kinases. The induction of transcription from the HIV-1 LTR in response to Ras signaling requires binding of the Ras-responsive element binding factor (RBF-2) to conserved cis elements flanking the enhancer region, designated RBE3 and RBE1. RBF-2 is composed minimally of the USF1, USF2, and TFII-I transcription factors. We recently determined that TFII-I regulates transcriptional elongation from the LTR through recruitment of the co-activator TRIM24. However, the function of USF1 and USF2 for this effect are uncharacterized. Here, we find that genetic deletion of USF2 but not USF1 in T cells inhibits HIV-1 expression. The loss of USF2 caused a reduction in expression of the USF1 protein, an effect that was not associated with decreased USF1 mRNA abundance. USF1 and USF2 were previously shown to exist predominately as heterodimers and to cooperatively regulate target genes. To examine cooperativity between these factors, we performed RNA-seq analysis of T cell lines bearing knockouts of the genes encoding these factors. In untreated cells, we found limited evidence of coordinated global gene regulation between USF1 and USF2. In contrast, we observed a high degree of genome-wide cooperative regulation of RNA expression between these factors in cells stimulated with the combination of PMA and ionomycin. In particular, we found that the deletion of USF1 or USF2 restricted T cell activation response. These observations indicate that USF2, but not USF1, is crucial for HIV-1 expression, while the combined function of these factors is required for a robust T cell inflammatory response.

USF2 activates RhoB/ROCK pathway by transcriptional inhibition of miR-206 to promote pyroptosis in septic cardiomyocytes.

Septic cardiomyopathy (SCM) is one of the most serious complications of sepsis. The present study investigated the role and mechanism of upstream stimulatory factor 2 (USF2) in SCM. Serum samples were extracted from SCM patients and healthy individuals. A murine model of sepsis was induced by caecal ligation and puncture (CLP) surgery. Myocardial injury was examined by echocardiography and HE staining. ELISA assay evaluated myocardial markers (CK-MB, cTnI) and inflammatory cytokines (TNF-α, IL-1ß, IL-18). Primary mouse cardiomyocytes were treated with lipopolysaccharide (LPS) to simulate sepsis in vitro. RT-qPCR and Western blot were used for analyzing gene and protein levels. CCK-8 assay assessed cell viability. NLRP3 was detected by immunofluorescence. ChIP, RIP and dual luciferase reporter assays were conducted to validate the molecular associations. USF2 was increased in serum from SCM patients, septic mice and primary cardiomyocytes. USF2 silencing improved the survival of septic mice and attenuated sepsis-induced myocardial pyroptosis and inflammation in vitro and in vivo. Mechanistically, USF2 could directly bind to the promoter of miR-206 to transcriptionally inhibit its expression. Moreover, RhoB was confirmed as a target of miR-206 and could promote ROCK activation and NLRP3 inflammasome formation. Moreover, overexpression of RhoB remarkably reversed the protection against LPS-induced inflammation and pyroptosis mediated by USF2 deletion or miR-206 overexpression in cardiomyocytes. The above findings elucidated that USF2 knockdown exerted a cardioprotective effect on sepsis by decreasing pyroptosis and inflammation via miR-206/RhoB/ROCK pathway, suggesting that USF2 may be a novel drug target in SCM.

A natural variation-based screen in mouse cells reveals USF2 as a regulator of the DNA damage response and cellular senescence.

Cellular senescence is a program of cell cycle arrest, apoptosis resistance, and cytokine release induced by stress exposure in metazoan cells. Landmark studies in laboratory mice have characterized a number of master senescence regulators, including p16INK4a, p21, NF-κB, p53, and C/EBPß. To discover other molecular players in senescence, we developed a screening approach to harness the evolutionary divergence between mouse species. We found that primary cells from the Mediterranean mouse Mus spretus, when treated with DNA damage to induce senescence, produced less cytokine and had less-active lysosomes than cells from laboratory Mus musculus. We used allele-specific expression profiling to catalog senescence-dependent cis-regulatory variation between the species at thousands of genes. We then tested for correlation between these expression changes and interspecies sequence variants in the binding sites of transcription factors. Among the emergent candidate senescence regulators, we chose a little-studied cell cycle factor, upstream stimulatory factor 2 (USF2), for molecular validation. In acute irradiation experiments, cells lacking USF2 had compromised DNA damage repair and response. Longer-term senescent cultures without USF2 mounted an exaggerated senescence regulatory program-shutting down cell cycle and DNA repair pathways, and turning up cytokine expression, more avidly than wild-type. We interpret these findings under a model of pro-repair, anti-senescence regulatory function by USF2. Our study affords new insights into the mechanisms by which cells commit to senescence, and serves as a validated proof of concept for natural variation-based regulator screens.

WDR3 promotes stem cell-like properties in prostate cancer by inhibiting USF2-mediated transcription of RASSF1A.

BACKGROUND: WD repeat domain 3 (WDR3) is involved in tumor growth and proliferation, but its role in the pathological mechanism of prostate cancer (PCa) is still unclear. METHODS: WDR3 gene expression levels were obtained by analyzing databases and our clinical specimens. The expression levels of genes and proteins were determined by a real-time polymerase chain reaction, western blotting and immunohistochemistry, respectively. Cell-counting kit-8 assays were used to measure the proliferation of PCa cells. Cell transfection was used to investigate the role of WDR3 and USF2 in PCa. Fluorescence reporter and chromatin immunoprecipitation assays were used to detect USF2 binding to the promoter region of RASSF1A. Mouse experiments were used to confirm the mechanism in vivo. RESULTS: By analyzing the database and our clinical specimens, we found that WDR3 expression was significantly increased in PCa tissues. Overexpression of WDR3 enhanced PCa cell proliferation, decreased cell apoptosis rate, increased spherical cell number and increased indicators of stem cell-like properties. However, these effects were reversed by WDR3 knockdown. WDR3 was negatively correlated with USF2, which was degraded by promoting ubiquitination of USF2, and USF2 interacted with promoter region-binding elements of RASSF1A to depress PCa stemness and growth. In vivo studies showed that WDR3 knockdown reduced tumor size and weight, reduced cell proliferation and enhanced cell apoptosis. CONCLUSIONS: WDR3 ubiquitinated USF2 and inhibited its stability, whereas USF2 interacted with promoter region-binding elements of RASSF1A. USF2 transcriptionally activated RASSF1A, which inhibited the carcinogenic effect of WDR3 overexpression.

GLI1, a novel target of the ER stress regulator p97/VCP, promotes ATF6f-mediated activation of XBP1.

Upon accumulation of improperly folded proteins in the Endoplasmic Reticulum (ER), the Unfolded Protein Response (UPR) is triggered to restore ER homeostasis. The induction of stress genes is a sine qua non condition for effective adaptive UPR. Although this requirement has been extensively described, the mechanisms underlying this process remain in part uncharacterized. Here, we show that p97/VCP, an AAA+ ATPase known to contribute to ER stress-induced gene expression, regulates the transcription factor GLI1, a primary effector of Hedgehog (Hh) signaling. Under basal (non-ER stress) conditions, GLI1 is repressed by a p97/VCP-HDAC1 complex while upon ER stress GLI1 is induced through a mechanism requiring both USF2 binding and increase histone acetylation at its promoter. Interestingly, the induction of GLI1 was independent of ligand-regulated Hh signaling. Further analysis showed that GLI1 cooperates with ATF6f to induce promoter activity and expression of XBP1, a key transcription factor driving UPR. Overall, our work demonstrates a novel role for GLI1 in the regulation of ER stress gene expression and defines the interplay between p97/VCP, HDAC1 and USF2 as essential players in this process.

Plasma PFOA and PFOS Levels, DNA Methylation, and Blood Lipid Levels: A Pilot Study.

Exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) is associated with blood lipids in adults, but the underlying mechanisms remain unclear. This pilot study aimed to investigate the associations between PFOA or PFOS and epigenome-wide DNA methylation and assess the mediating effect of DNA methylation on the PFOA/PFOS-blood lipid association. We measured plasma PFOA/PFOS and leukocyte DNA methylation in 98 patients enrolled from the hospital between October 2018 and August 2019. The median plasma PFOA/PFOS levels were 0.85 and 2.29 ng/mL. Plasma PFOA and PFOS levels were significantly associated with elevated total cholesterol (TC) and low-density lipoprotein cholesterol (LDL) levels. There were 63/87 CpG positions and 8/11 differentially methylated regions (DMRs) associated with plasma PFOA/PFOS levels, respectively. In addition, 5 CpG positions (annotated to AFF3, CREB5, NRG2, USF2, and intergenic region) and one DMR annotated to IRF6 may mediate the association between plasma PFOA/PFOS and LDL levels (mediated proportion from 7.29 to 46.77%); two CpG positions may mediate the association between plasma PFOA/PFOS and TC levels (annotated to CREB5 and USF2, mediated proportion is around 30%). The data suggest that PFOA/PFOS exposure alters DNA methylation. More importantly, the association of PFOA/PFOS with lipid indicators was partly mediated by DNA methylation changes in lipid metabolism-related genes.

Decorin-induced, preeclampsia-associated microRNA-512-3p restrains extravillous trophoblast functions by targeting USF2/PPP3R1 axis.

Decorin (DCN) is a leucine-rich proteoglycan produced by chorionic villus mesenchymal cells anddecidual cells during human pregnancy. Studies from our laboratory demonstrated that decidua-derived DCN restrains multiple trophoblast functions including proliferation, migration, invasion andendovascular differentiation, mediated by DCN-binding to multiple tyrosine kinase receptors; expressed by the trophoblast. Furthermore, DCN was shown to be selectively over-produced by thedecidua in preeclampsia (PE) subjects and elevated in the second trimester maternal plasma in PE, before the appearance of clinical signs, presenting as a predictive biomarker for PE. Micro (mi)RNAs are single-stranded non-coding RNAs (17-25 nucleotides) that typically downregulate target genes by repressing translation or facilitating degradation of mRNAs. The human; placenta expresses many miRNAs, some of which are exclusively expressed by the trophoblast. Many; of these miRNAs are dysregulated in PE-associated placentas and some appear in the maternal blood as PE biomarkers. However, little is known about their contribution to the pathogenesis of PE, a multi-factorial disease associated with a hypo-invasive placenta. The objective of the present study was to examine whether exposure of extravillous trophoblast (EVT) to DCN affects expression of specific miRNAs, and to test the role of these miRNAs in altering EVT functions. We identified miR-512-3p, as one of the DCN-induced miRNAs, also upregulated in PE placentas. It was shown to be elevated in ectopic DCN-over-expressing or exogenous DCN-treated first trimester human trophoblast cell line HTR-8/SVneo. Use of miRNA-mimics and inhibitors revealed that miR-512-3p compromised trophoblast migration, invasion and VEGF-dependent endovascular differentiation. Finally, Protein Phosphatase 3 Regulatory Subunit B, Alpha (PPP3R1), a known target of miR-512-3p, was paradoxically elevated in miR-512-3p-overexpressing trophoblast and PE-associated placentas. Using Enrichr, a tool that consists of both a validated user-submitted gene list and a search engine for transcription factors, we found that PPP3R1 elevation resulted from the miRNA binding to and targeting Upstream Transcription Factor 2 (USF2) which targeted PPP3R1. These findings reveal a novel aspect of pathogenesis of PE and biomarker potentials of this miRNA in PE.

hsa-miR-875-5p inhibits tumorigenesis and suppresses TGF-ß signalling by targeting USF2 in gastric cancer.

BACKGROUND: Gastric cancer (GC) is one of the most common malignancies, and an increasing number of studies have shown that its pathogenesis is regulated by various miRNAs. In this study, we investigated the role of miR-875-5p in GC. METHODS: The expression of miR-875-5p was detected in human GC specimens and cell lines by miRNA qRT-PCR. The effect of miR-875-5p on GC proliferation was determined by Cell Counting Kit-8 (CCK-8) proliferation and 5-ethynyl-2'-deoxyuridine (EdU) assays. Migration and invasion were examined by transwell migration and invasion assays as well as wound healing assays. The interaction between miR-875-5p and its target gene upstream stimulatory factor 2(USF2) was verified by dual luciferase reporter assays. The effects of miR-875-5p in vivo were studied in xenograft nude mouse models. Related proteins were detected by western blot. RESULTS: The results showed that miR-875-5p inhibited the proliferation, migration and invasion of GC cells in vitro and inhibited tumorigenesis in vivo. USF2 was proved to be a direct target of miR-875-5p. Knockdown of USF2 partially counteracted the effects of miR-875-5p inhibitor. Overexpression of miR-875-5p could inhibit proliferation, migration and invasion and suppress the TGF-ß signalling pathway by downregulating USF2. CONCLUSIONS: MiR-875-5p can inhibit the progression of GC by directly targeting USF2. And in the future, miR-875-5p is expected to be a potential target for GC diagnosis and treatment.

Upstream stimulatory factor 2 (USF2) induced upregulation of triggering receptor expressed on myeloid cells 1 (TREM1) promotes endometritis by regulating toll-like receptor (TLR) 2/4-nuclear factor-kappaB (NF-κB) signaling pathway.

Triggering receptor expressed on myeloid cells 1 (TREM1) participates in the development of endometritis. This study aims at identifying the effects and interaction of TREM1 and upstream stimulatory factor 2 (USF2) in endometritis by using a model of lipopolysaccharide (LPS)-induced human endometrial epithelial cells (HEnEpCs). ELISA was performed to determine the levels of interleukin (IL)-6, IL-1ß, and tumor necrosis factor (TNF-α) after LPS stimulation. TREM1 and USF2 expression was examined with RT-qPCR and Western blot. The JASPAR database was employed to predict the binding site between USF2 and TREM1, which was confirmed by luciferase reporter and chromatin immunoprecipitation assays. After TREM1 overexpression, IL-6, IL-1ß, and TNF-α expression was detected by ELISA. Next, the binding of TREM1 to toll-like receptor (TLR) 2/4 was examined with co-immunoprecipitation. Then, proteins in TLR2/4-nuclear factor-kappaB (NF-κB) signaling in HEnEpCs under LPS condition were assessed by Western blot or immunofluorescence before and after TREM1 knockdown. Finally, TLR2 or TLR4 was silenced to explore whether intervene TLR2/4-NF-κB signaling pathway could rescue TREM1-overexpression-induced inflammation in LPS-induced HEnEpCs. Results revealed that upregulated TREM1 was observed in LPS-challenged HEnEpCs. Next, USF2 was found to have transcriptionally active TREM1 expression. Additionally, USF2 knockdown decreased the levels of IL-6, IL-1ß, and TNF-α, whereas this effect was rescued after TREM1 overexpression. Besides, TREM1 could bind to TLR2/4 to regulate NF-κB signaling. Moreover, the intervention of TLR2/4-NF-κB signaling pathway rescued TREM1-overexpression-induced inflammation in LPS-stimulated HEnEpCs. Collectively, USF2 promotes endometritis by upregulating TREM1, thereby activating TLR2/4-NF-κB pathway.

USF2 knockdown downregulates THBS1 to inhibit the TGF-ß signaling pathway and reduce pyroptosis in sepsis-induced acute kidney injury.

OBJECTIVE: Acute kidney injury (AKI) is a serious complication of sepsis. This study was performed to explore the mechanism that THBS1 mediated pyroptosis by regulating the TGF-ß signaling pathway in sepsis-induced AKI. METHODS: Gene expression microarray related to sepsis-induced AKI was obtained from the GEO database, and the mechanism in sepsis-induced AKI was predicted by bioinformatics analysis. qRT-PCR and ELISA were performed to detect expressions of THBS1, USF2, TNF-α, IL-1ß, and IL-18 in sepsis-induced AKI patients and healthy volunteers. The mouse model of sepsis-induced AKI was established, with serum creatinine, urea nitrogen, 24-h urine output measured, and renal tissue lesions observed by HE staining. The cell model of sepsis-induced AKI was cultured in vitro, with expressions of TNF-α, IL-1ß, and IL-18, pyroptosis, Caspase-1 and GSDMD-N, and activation of TGF-ß/Smad3 pathway detected. The upstream transcription factor USF2 was knocked down in cells to explore its effect on sepsis-induced AKI. RESULTS: THBS1 and USF2 were highly expressed in patients with sepsis-induced AKI. Silencing THBS1 protected mice against sepsis-induced AKI, and significantly decreased the expressions of NLRP3, Caspase-1, GSDMD-N, IL-1ß, and IL-18, increased cell viability, and decreased LDH activity, thus partially reversing the changes in cell morphology. Mechanistically, USF2 promoted oxidative stress responses by transcriptionally activating THBS1 to activate the TGF-ß/Smad3/NLRP3/Caspase-1 signaling pathway and stimulate pyroptosis, and finally exacerbated sepsis-induced AKI. CONCLUSION: USF2 knockdown downregulates THBS1 to inhibit the TGF-ß/Smad3 signaling pathway and reduce pyroptosis and further ameliorate sepsis-induced AKI.

USF2 reduces BMP3 expression via transcriptional activation of miR-34a, thus promoting osteogenic differentiation of BMSCs.

INTRODUCTION: Osteoporosis is the most susceptible disease for people over 60. The main cause of osteoporosis is the decreased osteogenic differentiation of mesenchymal stem cells (MSCs). Here we showed that upstream stimulatory factor 2 (USF2)/microRNA-34a (miR-34a)/bone morphogenetic protein 3 (BMP3) axis regulated osteogenic differentiation of BMSCs. MATERIALS AND METHODS: USF2 and miR-34a expression were examined using qPCR. Protein levels of BMP3 and osteogenic markers expression were evaluated using both western blot and qPCR. Activity of ALP was determined by ALP assay kit. Mineralization capacity of hBMSCs was assessed using ARS. Besides, CHIP assay was employed to verify whether USF2 could bind to miR-34a promoter. Finally, RIP assay and dual-luciferase reporter assay were employed to verify whether miR-34a directly bound to BMP3. RESULTS: Our results suggested that miR-34a was upregulated during osteogenic differentiation of BMSCs, and miR-34a overexpression could enhance osteogenic differentiation of BMSCs. USF2 could positively regulate miR-34a expression by interacting with its promoter. USF2 overexpression enhanced osteogenic differentiation of BMSCs, while miR-34a inhibition reversed the effect. Besides, BMP3 was the target of miR-34a. MiR-34a overexpression enhanced osteogenic differentiation of BMSCs, which was abolished by BMP3 overexpression. CONCLUSION: Taken together, USF2 enhanced osteogenic differentiation of BMSCs via downregulating BMP3 by interacting with miR-34a promoter.

Epigenomic Analysis of RAD51 ChIP-seq Data Reveals cis-regulatory Elements Associated with Autophagy in Cancer Cell Lines.

RAD51 is a recombinase that plays a pivotal role in homologous recombination. Although the role of RAD51 in homologous recombination has been extensively studied, it is unclear whether RAD51 can be involved in gene regulation as a co-factor. In this study, we found evidence that RAD51 may contribute to the regulation of genes involved in the autophagy pathway with E-box proteins such as USF1, USF2, and/or MITF in GM12878, HepG2, K562, and MCF-7 cell lines. The canonical USF binding motif (CACGTG) was significantly identified at RAD51-bound cis-regulatory elements in all four cell lines. In addition, genome-wide USF1, USF2, and/or MITF-binding regions significantly coincided with the RAD51-associated cis-regulatory elements in the same cell line. Interestingly, the promoters of genes associated with the autophagy pathway, such as ATG3 and ATG5, were significantly occupied by RAD51 and regulated by RAD51 in HepG2 and MCF-7 cell lines. Taken together, these results unveiled a novel role of RAD51 and provided evidence that RAD51-associated cis-regulatory elements could possibly be involved in regulating autophagy-related genes with E-box binding proteins.

Protective mechanism of apigenin in diabetic nephropathy is related to its regulation of miR-423-5P-USF2 axis.

Apigenin (APG), a natural flavonoid with anti-inflammatory and anti-fibrosis properties, has been shown to play a protective role in diabetic nephropathy (DN), but their molecular protection mechanism for miRNA has not been elucidated in detail. This study was designed to focus on exploring its protective role in DN and whether miR-423-5p-upstream stimulating factor 2 (USF2) axis was involved in its protective mechanism. The in vivo model of rat was induced by streptozotocin (STZ) and the in vitro model of renal tubular epithelial cell (RTEC) was induced by high glucose (HG). Our in vivo study revealed that APG had different protective effects on inflammation, renal fibrosis and epithelial mesenchymal transition (EMT) in DN rats, which is mainly reflected in that the inflammatory factors (IL-6, IFN-γ, TNF-α) were obviously down-regulated, the renal fibrosis markers (IV-C, FN, Col I) were significantly inhibited, the E-cadherin (EMT factors) was significantly up-regulated, while the vimentin and α-SMA (EMT factors) were significantly down-regulated, and the renal function indexes (serum Cr, BUN) were significantly improved. In terms of mechanism, the protective effect of APG was related to the regulation of the expression of miR-423-5p-USF2 axis, and there was a targeted relationship between miR-423-5p and USF2. Down-regulating miR-423-5p or up-regulating USF2 could significantly aggravate the disease progression of in vitro model and eliminate DN resistance under APG intervention. The above results revealed that the protective role of APG on DN was mediated by miR-423-5p-USF2 axis.

Identification of the core promoter of ZNFO, an oocyte-specific maternal effect gene in cattle.

ZNFO is a Krüppel-associated box (KRAB) containing zinc finger transcription factor, which is exclusively expressed in bovine oocytes. Previous studies have demonstrated that ZNFO possesses an intrinsic transcriptional repressive activity and is essential for early embryonic development in cattle. However, the mechanisms regulating ZNFO transcription remain elusive. In the present study, the core promoter that controls the ZNFO basal transcription was identified. A 1.7 kb 5' regulatory region of the ZNFO gene was cloned and its promoter activity was confirmed by a luciferase reporter assay. A series of 5' deletion in the ZNFO promoter followed by luciferase reporter assays indicated that the core promoter region has to include the sequence located within 57 bp to 31 bp upstream of the transcription start site. Sequence analysis revealed that a putative USF1/USF2 binding site (GGTCACGTGACC) containing an E-box motif (CACGTG) is located within the essential region. Depletion of USF1/USF2 by RNAi and E-box mutation analysis demonstrated that the USF1/USF2 binding site is required for the ZNFO basal transcription. Furthermore, EMSA and super-shift assays indicated that the observed effects are dependent on the specific interactions between USF proteins and the ZNFO core promoter. From these results, it is concluded that USF1 and USF2 are essential for the basal transcription of the ZNFO gene.

Aberrant expression of USF2 in refractory rheumatoid arthritis and its regulation of proinflammatory cytokines in Th17 cells.

IL-17-producing Th17 cells are implicated in the pathogenesis of rheumatoid arthritis (RA) and TNF-α, a proinflammatory cytokine in the rheumatoid joint, facilitates Th17 differentiation. Anti-TNF therapy ameliorates disease in many patients with rheumatoid arthritis (RA). However, a significant proportion of patients do not respond to this therapy. The impact of anti-TNF therapy on Th17 responses in RA is not well understood. We conducted high-throughput gene expression analysis of Th17-enriched CCR6+CXCR3-CD45RA- CD4+ T (CCR6+ T) cells isolated from anti-TNF-treated RA patients classified as responders or nonresponders to therapy. CCR6+ T cells from responders and nonresponders had distinct gene expression profiles. Proinflammatory signaling was elevated in the CCR6+ T cells of nonresponders, and pathogenic Th17 signature genes were up-regulated in these cells. Gene set enrichment analysis on these signature genes identified transcription factor USF2 as their upstream regulator, which was also increased in nonresponders. Importantly, short hairpin RNA targeting USF2 in pathogenic Th17 cells led to reduced expression of proinflammatory cytokines IL-17A, IFN-γ, IL-22, and granulocyte-macrophage colony-stimulating factor (GM-CSF) as well as transcription factor T-bet. Together, our results revealed inadequate suppression of Th17 responses by anti-TNF in nonresponders, and direct targeting of the USF2-signaling pathway may be a potential therapeutic approach in the anti-TNF refractory RA.

Loss of USF2 promotes proliferation, migration and mitophagy in a redox-dependent manner.

The upstream stimulatory factor 2 (USF2) is a transcription factor implicated in several cellular processes and among them, tumor development seems to stand out. However, the data with respect to the role of USF2 in tumor development are conflicting suggesting that it acts either as tumor promoter or suppressor. Here we show that absence of USF2 promotes proliferation and migration. Thereby, we reveal a previously unknown function of USF2 in mitochondrial homeostasis. Mechanistically, we demonstrate that deficiency of USF2 promotes survival by inducing mitophagy in a ROS-sensitive manner by activating both ERK1/2 and AKT. Altogether, this study supports USF2's function as tumor suppressor and highlights its novel role for mitochondrial function and energy homeostasis thereby linking USF2 to conditions such as insulin resistance, type-2 diabetes mellitus, and the metabolic syndrome.

A novel protein upstream stimulatory factor 2 identified in lamprey, Lethenteron reissneri.

Upstream stimulatory factors are kinds of multi-functional transcription factors, which are expressed in eukaryotes widely, including Upstream stimulatory factor 1 (USFl) and upstream stimulatory factor 2 (USF2). USF protein has a typical basic helix-loop-helix leucine zipper (b-HLH-LZ) structure, which is involved in cell cycle, cell proliferations, glucose and lipid metabolism, and other biochemical processes. Although the USF family is an important regulator of cellular processes, little is known about the USF genes of lampreys, especially their evolutionary relationships, expression profiles, and biological functions. Here, an upstream stimulatory factor 2 (USF2) homolog from lamprey (Lethenteron reissneri) was identified and characterized (designated as L-USF2) because it is closer to USF2 subfamily than to USF1 subfamily. The cDNA fragment of L-USF2 has an open reading frame (ORF) of 765-bp length, encodes 254 amino acids, and contains an HLH domain at the c-terminal of amino acids. Meanwhile, motifs and genetic structure analysis reveal that USF2 gene exons are conserved. Moreover, the 3D structure analysis indicates that L-USF2 adopts the general USF2 folding and has a high structural similarity with H-USF2. The synteny results showed that the L-USF2 adjacent gene changed greatly compared with the jaw vertebrates. By real-time quantitative experiment and Western blot analysis, we found that L-USF2 gene played a significant role in the immune responses. This study not only provides us with a further understanding of the evolution and function of the USF gene family but also provides a basis for exploring its immune responses and immune defenses in lampreys.