Dysregulation of TNF-induced protein 3 and CCAAT/enhancer-binding protein ß in alveolar macrophages: Implications for systemic sclerosis-associated interstitial lung disease.

OBJECTIVES: This study investigates the role of TNF-induced protein 3 (TNFAIP3) and CCAAT/enhancer-binding protein ß (C/EBPß) in alveolar macrophages (AMs) of patients with systemic sclerosis-associated interstitial lung disease (SSc-ILD) and their influence on pulmonary fibrosis. METHODS: Transfection of HEK293T cells and AMs with plasmids carrying TNFAIP3 and C/EBPß was performed, followed by co-culturing AMs with pulmonary fibroblasts. Immunoblotting analysis was then utilized to assess the expression of TNFAIP3, C/EBPß, and collagen type 1 (Col1). Quantitative PCR analysis was conducted to quantify the mRNA levels of C/EBPß, IL-10, and TGF-ß1. STRING database analysis, and immunoprecipitation assays were employed to investigate the interactions between TNFAIP3 and C/EBPß. RESULTS: TNFAIP3 expression was significantly reduced in SSc-ILD AMs, correlating with increased Col1 production in fibroblasts. Overexpression of TNFAIP3 inhibited this pro-fibrotic activity. Conversely, C/EBPß expression was elevated in SSc-ILD AMs, and its reduction through TNFAIP3 restoration decreased pro-fibrotic cytokines IL-10 and TGFß1 levels. Protein-protein interaction studies confirmed the regulatory relationship between TNFAIP3 and C/EBPß. CONCLUSIONS: This study highlights the important role of TNFAIP3 in regulating pulmonary fibrosis in SSc-ILD by modulating C/EBPß expression in AMs. These findings suggest that targeting TNFAIP3 could be a potential therapeutic strategy for managing SSc-ILD patients.

Midkine promotes renal fibrosis by stabilizing C/EBPß to facilitate endothelial-mesenchymal transition.

Numerous myofibroblasts are arisen from endothelial cells (ECs) through endothelial to mesenchymal transition (EndMT) triggered by TGF-ß. However, the mechanism of ECs transforms to a different subtype, or whether there exists an intermediate state of ECs remains unclear. In present study, we demonstrate Midkine (MDK) mainly expressed by CD31 + ACTA2+ECs going through partial EndMT contribute greatly to myofibroblasts by spatial and single-cell transcriptomics. MDK is induced in TGF-ß treated ECs, which upregulates C/EBPß and increases EndMT genes, and these effects could be reversed by siMDK. Mechanistically, MDK promotes the binding ability of C/EBPß with ACTA2 promoter by stabilizing the C/EBPß protein. In vivo, knockout of Mdk or conditional knockout of Mdk in ECs reduces EndMT markers and significantly reverses fibrogenesis. In conclusion, our study provides a mechanistic link between the induction of EndMT by TGF-ß and MDK, which suggests that blocking MDK provides potential therapeutic strategies for renal fibrosis.

C/EBPß: A transcription factor associated with the irreversible progression of Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is a neurodegenerative disorder distinguished by a swift cognitive deterioration accompanied by distinctive pathological hallmarks such as extracellular Aß (ß-amyloid) peptides, neuronal neurofibrillary tangles (NFTs), sustained neuroinflammation, and synaptic degeneration. The elevated frequency of AD cases and its proclivity to manifest at a younger age present a pressing challenge in the quest for novel therapeutic interventions. Numerous investigations have substantiated the involvement of C/EBPß in the progression of AD pathology, thus indicating its potential as a therapeutic target for AD treatment. AIMS: Several studies have demonstrated an elevation in the expression level of C/EBPß among individuals afflicted with AD. Consequently, this review predominantly delves into the association between C/EBPß expression and the pathological progression of Alzheimer's disease, elucidating its underlying molecular mechanism, and pointing out the possibility that C/EBPß can be a new therapeutic target for AD. METHODS: A systematic literature search was performed across multiple databases, including PubMed, Google Scholar, and so on, utilizing predetermined keywords and MeSH terms, without temporal constraints. The inclusion criteria encompassed diverse study designs, such as experimental, case-control, and cohort studies, restricted to publications in the English language, while conference abstracts and unpublished sources were excluded. RESULTS: Overexpression of C/EBPß exacerbates the pathological features of AD, primarily by promoting neuroinflammation and mediating the transcriptional regulation of key molecular pathways, including δ-secretase, apolipoprotein E4 (APOE4), acidic leucine-rich nuclear phosphoprotein-32A (ANP32A), transient receptor potential channel 1 (TRPC1), and Forkhead BoxO (FOXO). DISCUSSION: The correlation between overexpression of C/EBPß and the pathological development of AD, along with its molecular mechanisms, is evident. Investigating the pathways through which C/EBPß regulates the development of AD reveals numerous multiple vicious cycle pathways exacerbating the pathological progression of the disease. Furthermore, the exacerbation of pathological progression due to C/EBPß overexpression and its molecular mechanism is not limited to AD but also extends to other neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and multiple sclerosis (MS). CONCLUSION: The overexpression of C/EBPß accelerates the irreversible progression of AD pathophysiology. Additionally, C/EBPß plays a crucial role in mediating multiple pathways linked to AD pathology, some of which engender vicious cycles, leading to the establishment of feedback mechanisms. To sum up, targeting C/EBPß could hold promise as a therapeutic strategy not only for AD but also for other degenerative diseases.

TG-interacting factor 1 regulates mitotic clonal expansion during adipocyte differentiation.

Obesity is one of the significant health challenges in the world and is highly associated with abnormal adipogenesis. TG-interacting factor 1 (TGIF1) is essential for differentiating murine adipocytes and human adipose tissue-derived stem cells. However, the mode of action needs to be better elucidated. To investigate the roles of TGIF1 in differentiation in-depth, CRISPR/Cas9 knockout technology was performed to generate TGIF1-silenced preadipocytes. The absence of TGIF1 in 3 T3-F442A preadipocytes abolished lipid accumulation throughout the differentiation using Oil Red O staining. Conversely, we established 3 T3-F442A preadipocytes stably expressing TGIF1 and doxycycline-inducible TGIF1 in TGIF1-silenced 3 T3-F442A preadipocytes. Remarkably, the induction of TGIF1 by doxycycline during the initial differentiation phase successfully promoted lipid accumulation in TGIF1-silenced 3 T3-F442A cells. We further explored the mechanisms of TGIF1 in early differentiation. We demonstrated that TGIF1 promoted the mitotic clonal expansion via upregulation of CCAAT/enhancer-binding proteins ß expression, interruption with peroxisome proliferators activated receptor γ downstream regulation, and inhibition of p27kip1 expression. In conclusion, we strengthen the pivotal roles of TGIF1 in early differentiation, which might contribute to resolving obesity-associated metabolic syndromes.

The Involvement of the microRNAs miR-466c and miR-340 in the Palmitate-Mediated Dysregulation of Gonadotropin-Releasing Hormone Gene Expression.

Diets high in saturated fatty acids are associated with obesity and infertility. Palmitate, the most prevalent circulating saturated fatty acid, is sensed by hypothalamic neurons, contributing to homeostatic dysregulation. Notably, palmitate elevates the mRNA levels of gonadotropin-releasing hormone (Gnrh) mRNA and its activating transcription factor, GATA binding protein 4 (Gata4). GATA4 is essential for basal Gnrh expression by binding to its enhancer region, with Oct-1 (Oct1) and CEBP-ß (Cebpb) playing regulatory roles. The pre- and post-transcriptional control of Gnrh by palmitate have not been investigated. Given the ability of palmitate to alter microRNAs (miRNAs), we hypothesized that palmitate-mediated dysregulation of Gnrh mRNA involves specific miRNAs. In the mHypoA-GnRH/GFP neurons, palmitate significantly downregulated six miRNAs (miR-125a, miR-181b, miR-340, miR-351, miR-466c and miR-503), and the repression was attenuated by co-treatment with 100 µM of oleate. Subsequent mimic transfections revealed that miR-466c significantly downregulates Gnrh, Gata4, and Chop mRNA and increases Per2, whereas miR-340 upregulates Gnrh, Gata4, Oct1, Cebpb, and Per2 mRNA. Our findings suggest that palmitate may indirectly regulate Gnrh at both the pre- and post-transcriptional levels by altering miR-466c and miR-340, which in turn regulate transcription factor expression levels. In summary, palmitate-mediated dysregulation of Gnrh and, consequently, reproductive function involves parallel transcriptional mechanisms.

Exosomal long non-coding RNA AU020206 alleviates macrophage pyroptosis in atherosclerosis by suppressing CEBPB-mediated NLRP3 transcription.

Recent studies have suggested exosomes (EXO) as potential therapeutic tools for cardiovascular diseases, including atherosclerosis (AS). This study investigates the function of bone marrow stem cell (BMSC)-derived exosomes (EXO) on macrophage pyroptosis in AS and explores the associated mechanism. BMSC-EXO were isolated from healthy mice and identified. RAW264.7 cells (mouse macrophages) were exposed to oxLDL to simulate an AS condition. BMSC-EXO treatment enhanced viability and reduced lactate dehydrogenase release of macrophages. An animal model of AS was established using ApoE-/- mice. BMSC-EXO treatment suppressed plaque formation as well as macrophage and lipid infiltration in mouse aortic tissues. Moreover, BMSC-EXO decreased concentrations of pyroptosis-related markers interleukin (IL)-1ß, IL-18, cleaved-caspase-1 and gasdermin D in vitro and in vivo. Long non-coding RNA AU020206 was carried by the BMSC-EXO, and it bound to CCAAT enhancer binding protein beta (CEBPB) to block CEBPB-mediated transcriptional activation of NLR family pyrin domain containing 3 (NLRP3). Functional assays revealed that silencing of AU020206 aggravated macrophage pyroptosis and exacerbated AS symptoms in mice. These exacerbations were blocked upon CEBPB silencing but then restored after NLRP3 overexpression. In conclusion, this study demonstrates that AU020206 delivered by BMSC-EXO alleviates macrophage pyroptosis in AS by blocking CEBPB-mediated transcriptional activation of NLRP3.

rs822336 binding to C/EBPß and NFIC modulates induction of PD-L1 expression and predicts anti-PD-1/PD-L1 therapy in advanced NSCLC.

Efficient predictive biomarkers are needed for immune checkpoint inhibitor (ICI)-based immunotherapy in non-small cell lung cancer (NSCLC). Testing the predictive value of single nucleotide polymorphisms (SNPs) in programmed cell death 1 (PD-1) or its ligand 1 (PD-L1) has shown contrasting results. Here, we aim to validate the predictive value of PD-L1 SNPs in advanced NSCLC patients treated with ICIs as well as to define the molecular mechanisms underlying the role of the identified SNP candidate. rs822336 efficiently predicted response to anti-PD-1/PD-L1 immunotherapy in advanced non-oncogene addicted NSCLC patients as compared to rs2282055 and rs4143815. rs822336 mapped to the promoter/enhancer region of PD-L1, differentially affecting the induction of PD-L1 expression in human NSCLC cell lines as well as their susceptibility to HLA class I antigen matched PBMCs incubated with anti-PD-1 monoclonal antibody nivolumab. The induction of PD-L1 expression by rs822336 was mediated by a competitive allele-specificity binding of two identified transcription factors: C/EBPß and NFIC. As a result, silencing of C/EBPß and NFIC differentially regulated the induction of PD-L1 expression in human NSCLC cell lines carrying different rs822336 genotypes. Analysis by binding microarray further validated the competitive allele-specificity binding of C/EBPß and NFIC to PD-L1 promoter/enhancer region based on rs822336 genotype in human NSCLC cell lines. These findings have high clinical relevance since identify rs822336 and induction of PD-L1 expression as novel biomarkers for predicting anti-PD-1/PD-L1-based immunotherapy in advanced NSCLC patients.

Transcription factor CEBPB mediates intracranial aneurysm rupture by inflammatory and immune response.

INTRODUCTION: Genetic factors play a major part in mediating intracranial aneurysm (IA) rupture. However, research on the role of transcription factors (TFs) in IA rupture is rare. AIMS: Bioinformatics analysis was performed to explore the TFs and related functional pathways involved in IA rupture. RESULTS: A total of 63 differentially expressed transcription factors (DETFs) were obtained. Significantly enriched biological processes of these DETFs were related to regulation of myeloid leukocyte differentiation. The top 10 DETFs were screened based on the MCC algorithm from the protein-protein interaction network. After screening and validation, it was finally determined that CEBPB may be the hub gene for aneurysm rupture. The GSEA results of CEBPB were mainly associated with the inflammatory response, which was also verified by the experimental model of cellular inflammation in vitro. CONCLUSION: The inflammatory and immune response may be closely associated with aneurysm rupture. CEBPB may be the hub gene for aneurysm rupture and may have diagnostic value. Therefore, CEBPB may serve as the diagnostic signature for RIAs and a potential target for intervention.

ERK1/2-CEBPB Axis-Regulated hBD1 Enhances Anti-Tuberculosis Capacity in Alveolar Type II Epithelial Cells.

Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), remains a global health crisis with substantial morbidity and mortality rates. Type II alveolar epithelial cells (AEC-II) play a critical role in the pulmonary immune response against Mtb infection by secreting effector molecules such as antimicrobial peptides (AMPs). Here, human ß-defensin 1 (hBD1), an important AMP produced by AEC-II, has been demonstrated to exert potent anti-tuberculosis activity. HBD1 overexpression effectively inhibited Mtb proliferation in AEC-II, while mice lacking hBD1 exhibited susceptibility to Mtb and increased lung tissue inflammation. Mechanistically, in A549 cells infected with Mtb, STAT1 negatively regulated hBD1 transcription, while CEBPB was the primary transcription factor upregulating hBD1 expression. Furthermore, we revealed that the ERK1/2 signaling pathway activated by Mtb infection led to CEBPB phosphorylation and nuclear translocation, which subsequently promoted hBD1 expression. Our findings suggest that the ERK1/2-CEBPB-hBD1 regulatory axis can be a potential therapeutic target for anti-tuberculosis therapy aimed at enhancing the immune response of AEC-II cells.

MiR-155-5p improves the insulin sensitivity of trophoblasts by targeting CEBPB in gestational diabetes mellitus.

INTRODUCTION: Gestational diabetes mellitus (GDM) is a prevalent pregnancy complication featuring impaired insulin sensitivity. MiR-155-5p is associated with various metabolic diseases. However, its specific role in GDM remains unclear. CCAAT enhancer binding protein beta (CEBPB), a critical role in regulating glucolipid metabolism, has been identified as a potential target of miR-155-5p. This study aims to investigate the impact of miR-155-5p and CEBPB on insulin sensitivity of trophoblasts in GDM. METHODS: Placental tissues were obtained from GDM and normal pregnant women; miR-155-5p expression was then evaluated by RT‒qPCR and CEBPB expression by western blot and immunohistochemical staining. To investigate the impact of miR-155-5p on insulin sensitivity and CEBPB expression, HTR-8/SVneo cells were transfected with either miR-155-5p mimic or inhibitor under basal and insulin-stimulated conditions. Cellular glucose uptake consumption was quantified using a glucose assay kit. Furthermore, the targeting relationship between miR-155-5p and CEBPB was validated using a dual luciferase reporter assay. RESULTS: Reduced miR-155-5p expression and elevated CEBPB expression were observed in GDM placentas and high glucose treated HTR8/SVneo cells. The overexpression of miR-155-5p significantly enhanced insulin signaling and glucose uptake in trophoblasts. Conversely, inhibiting miR-155-5p induced the opposite effects. Additionally, CEBPB was directly targeted and negatively regulated by miR-155-5p in HTR8/SVneo cells. Silencing CEBPB effectively restored the inhibitory effect of miR-155-5p downregulation on insulin sensitivity in trophoblasts. DISCUSSION: These findings suggest that miR-155-5p could enhance insulin sensitivity in trophoblasts by targeting CEBPB, highlighting the potential of miR-155-5p as a therapeutic target for improving the intrauterine hyperglycemic environment in GDM.

[C/EBPß mediates expressions of downstream inflammatory factors of the tumor necrosis factor-α signaling pathway in renal tubular epithelial cells with NPHP1 knockdown].

OBJECTIVE: To explore the activation of tumor necrosis factor-α (TNF-α) signaling pathway and the expressions of the associated inflammatory factors in NPHP1-defective renal tubular epithelial cells. METHODS: A human proximal renal tubular cell (HK2) model of lentivirus-mediated NPHP1 knockdown (NPHP1KD) was constructed, and the expressions of TNF-α, p38, and C/EBPß and the inflammatory factors CXCL5, CCL20, IL-1ß, IL-6 and MCP-1 were detected using RT-qPCR, Western blotting or enzyme-linked immunosorbent assay. A small interfering RNA (siRNA) was transfected in wild-type and NPHP1KDHK2 cells, and the changes in the expressions of TNF-α, p38, and C/EBPß and the inflammatory factors were examined. RESULTS: NPHP1KDHK2 cells showed significantly increased mRNA expressions of TNF-α, C/EBPß, CXCL5, IL-1ß, and IL-6 (P < 0.05), protein expressions of phospho-p38 and C/EBPß (P < 0.05), and IL-6 level in the culture supernatant (P < 0.05), and these changes were significantly blocked by transfection of cells with siRNA-C/EBPß (P < 0.05). CONCLUSION: TNF-α signaling pathway is activated and its associated inflammatory factors are upregulated in NPHP1KDHK2 cells, and C/EBPß may serve as a key transcription factor to mediate these changes.

Itraconazole inhibits tumor growth via CEBPB-mediated glycolysis in colorectal cancer.

Advanced colorectal cancer (CRC) is characterized by a high recurrence and metastasis rate, which is the primary cause of patient mortality. Unfortunately, effective anti-cancer drugs for CRC are still lacking in clinical practice. We screened FDA-approved drugs by utilizing targeted organoid sequencing data and found that the antifungal drug itraconazole had a potential therapeutic effect on CRC tumors. However, the effect and mechanism of itraconazole on CRC tumors have not been investigated. A cell line-derived xenograft model in tumor-bearing mice was established and single-cell RNA sequencing was performed on tumor samples from four mice with or without itraconazole treatment. The proportion of cell populations and gene expression profiles was significantly different between the two groups. We found that itraconazole could inhibit tumor growth and glycolysis. We revealed that CEBPB was a new target for itraconazole, and that silencing CEBPB could repress CRC glycolysis and tumor growth by inhibiting ENO1 expression. Clinical analysis showed that CEBPB expression was obviously elevated in CRC patients, and was associated with poor survival. In summary, itraconazole treatment remodeled cell composition and gene expression profiles. Itraconazole inhibited cell glycolysis and tumor growth via the CEBPB-ENO1 axis. In this study, we illustrate a new energy metabolism mechanism for itraconazole on tumor growth in CRC that will provide a theoretical basis for CRC targeting/combination therapy.

Deficiency of circadian clock gene Bmal1 exacerbates noncanonical inflammasome-mediated pyroptosis and lethality via Rev-erbα-C/EBPß-SAA1 axis.

Circadian arrhythmia has been linked to increased susceptibility to multiple inflammatory diseases, such as sepsis. However, it remains unclear how disruption of the circadian clock modulates molecular aspects of innate immune responses, including inflammasome signaling. Here, we examined the potential role of the circadian clock in inflammasome-mediated responses through myeloid-specific deletion of BMAL1, a master circadian clock regulator. Intriguingly, Bmal1 deficiency significantly enhanced pyroptosis of macrophages and lethality of mice under noncanonical inflammasome-activating conditions but did not alter canonical inflammasome responses. Transcriptome analysis of enriched peritoneal myeloid cells revealed that Bmal1 deficiency led to a marked reduction in Rev-erbα expression at steady state and a significant increase in serum amyloid A1 (SAA1) expression upon poly(I:C) stimulation. Notably, we found that the circadian regulator Rev-erbα is critical for poly(I:C)- or interferon (IFN)-ß-induced SAA1 production, resulting in the circadian oscillation pattern of SAA1 expression in myeloid cells. Furthermore, exogenously applied SAA1 markedly increased noncanonical inflammasome-mediated pyroptosis of macrophages and lethality of mice. Intriguingly, our results revealed that type 1 IFN receptor signaling is needed for poly(I:C)- or IFN-ß-induced SAA1 production. Downstream of the type 1 IFN receptor, Rev-erbα inhibited the IFN-ß-induced association of C/EBPß with the promoter region of Saa1, leading to the reduced transcription of Saa1 in macrophages. Bmal1-deficient macrophages exhibited enhanced binding of C/EBPß to Saa1. Consistently, the blockade of Rev-erbα by SR8278 significantly increased poly(I:C)-stimulated SAA1 transcription and noncanonical inflammasome-mediated lethality in mice. Collectively, our data demonstrate a potent suppressive effect of the circadian clock BMAL1 on the noncanonical inflammasome response via the Rev-erbα-C/EBPß-SAA1 axis.

CircDYM attenuates microglial apoptosis via CEBPB/ZC3H4 axis in LPS-induced mouse model of depression.

Major depressive disorder (MDD) is a highly prevalent condition and one of the most common psychiatric disorders worldwide. Circular RNA (circRNA) has been increasingly implicated in MDD. However, a comprehensive understanding of circRNA and microglial apoptosis in depression is incomplete. Here, we show that circDYM inhibits microglial apoptosis induced by LPS via CEBPB/ZC3H4 axis. CircDYM prevents the translocation of CEBPB from cytoplasm to the nucleus by binding with CEBPB. Moreover, LPS-induced CEBPB nuclear entry downregulates the expression of ZC3H4, in which promotes autophagy and apoptosis in microglia. Taken together, our findings provide new insights into the relationship between circDYM and microglial apoptosis and shed new light on the function of this novel mechanism in depression-associated complex changes in the brain.

Transcriptional factor CCAAT enhancer binding protein beta inhibits epithelial-mesenchymal transition in cervical cancer via regulating attractin-like 1.

Cervical cancer (CC) is a malignancy seriously endangering women's life and health worldwide. GEPIA demonstrated that attractin-like 1 (ATRNL1) presents downregulation in CC tissue. Transcription factor CCAAT enhancer binding protein beta (CEBPB) was previously revealed to present depletion in CC tissue. We attempted to clarify molecular mechanism between ATRNL1 and CEBPB underlying CC progression. Bioinformatics, RT-qPCR and western blotting revealed expression characteristics of ATRNL1 in CC. RT-qPCR measured ATRNL1 and CEBPB levels in CC cell lines. Gain-of-function assays clarified role of ATRNL1 in CC cell behaviors. Bioinformatics, Pearson correlation, ChIP and luciferase reporter experiments assessed association of ATRNL1 and CEBPB in CC cells. Rescue assays assessed regulatory function of CEBPB-ATRNL1 in CC cellular processes. ATRNL1 showed depletion in CC tissue and cells at mRNA and protein levels. ATRNL1 upregulation repressed CC cell viability, migration and EMT. CEBPB bound to ATRNL1 promoter to transcriptionally upregulate ATRNL1 in CC cells. The impact of CEBPB elevation on CC cell viability, migration and EMT were countervailed by ATRNL1 depletion. ATRNL1 and CEBPB present depletion and serve as tumor suppressors in CC cells. ATRNL1 suppresses CC cell malignancy through CEBPB activation, which may provide a potential new direction for seeking therapeutic plans for CC.

Deubiquitinase USP1 enhances CCAAT/enhancer-binding protein beta (C/EBPß) stability and accelerates adipogenesis and lipid accumulation.

Dysregulation of the ubiquitin-proteasome system has been implicated in the pathogenesis of several metabolic disorders, including obesity, diabetes, and non-alcoholic fatty liver disease; however, the mechanisms controlling pathogenic metabolic disorders remain unclear. Transcription factor CCAAT/enhancer binding protein beta (C/EBPß) regulates adipogenic genes. The study showed that the expression level of C/EBPß is post-translationally regulated by the deubiquitinase ubiquitin-specific protease 1 (USP1) and that USP1 expression is remarkably upregulated during adipocyte differentiation and in the adipose tissue of mice fed a high-fat diet (HFD). We found that USP1 directly interacts with C/EBPß. Knock-down of USP1 decreased C/EBPß protein stability and increased its ubiquitination. Overexpression of USP1 regulates its protein stability and ubiquitination, whereas catalytic mutant of USP1 had no effect on them. It suggests that USP1 directly deubiquitinases C/EBPß and increases the protein expression, leading to adipogenesis and lipid accumulation. Notably, the USP1-specific inhibitor ML323-originally developed to sensitize cancer cells to DNA-damaging agents-decreased adipocyte differentiation and lipid accumulation in 3T3-L1 cells without cytotoxicity. Oral gavage of ML323 was administered to HFD-fed mice, which showed weight loss and improvement in insulin and glucose sensitivity. Both fat mass and adipocyte size in white adipose tissues were significantly reduced by ML323 treatment, which also reduced the expression of genes involved in adipogenesis and inflammatory responses. ML323 also reduced lipid accumulation, hepatic triglycerides, free fatty acids, and macrophage infiltration in the livers of HFD-fed mice. Taken together, we suggest that USP1 plays an important role in adipogenesis by regulating C/EBPß ubiquitination, and USP1-specific inhibitor ML323 is a potential treatment option and further study by ML323 is needed for clinical application for metabolic disorders.

CRISPR screen identifies CEBPB as contributor to dyskeratosis congenita fibroblast senescence via augmented inflammatory gene response.

Aging is the consequence of intra- and extracellular events that promote cellular senescence. Dyskeratosis congenita (DC) is an example of a premature aging disorder caused by underlying telomere/telomerase-related mutations. Cells from these patients offer an opportunity to study telomere-related aging and senescence. Our previous work has found that telomere shortening stimulates DNA damage responses (DDRs) and increases reactive oxygen species (ROS), thereby promoting entry into senescence. This work also found that telomere elongation via TERT expression, the catalytic component of the telomere-elongating enzyme telomerase, or p53 shRNA could decrease ROS by disrupting this telomere-DDR-ROS pathway. To further characterize this pathway, we performed a CRISPR/Cas9 knockout screen to identify genes that extend life span in DC cells. Of the cellular clones isolated due to increased life span, 34% had a guide RNA (gRNA) targeting CEBPB, while gRNAs targeting WSB1, MED28, and p73 were observed multiple times. CEBPB is a transcription factor associated with activation of proinflammatory response genes suggesting that inflammation may be present in DC cells. The inflammatory response was investigated using RNA sequencing to compare DC and control cells. Expression of inflammatory genes was found to be significantly elevated (P < 0.0001) in addition to a key subset of these inflammation-related genes [IL1B, IL6, IL8, IL12A, CXCL1 (GROa), CXCL2 (GROb), and CXCL5]. which are regulated by CEBPB. Exogenous TERT expression led to downregulation of RNA/protein CEBPB expression and the inflammatory response genes suggesting a telomere length-dependent mechanism to regulate CEBPB. Furthermore, unlike exogenous TERT and p53 shRNA, CEBPB shRNA did not significantly decrease ROS suggesting that CEBPB's contribution in DC cells' senescence is ROS independent. Our findings demonstrate a key role for CEBPB in engaging senescence by mobilizing an inflammatory response within DC cells.

P53 regulates CCAAT/Enhancer binding protein ß gene expression.

BACKGROUND: The transcription factor CCAAT/enhancer-binding protein ß (C/EBPß) is implicated in diverse processes and diseases. Its two isoforms, namely liver-enriched activator protein (LAP) and liver-enriched inhibitor protein (LIP) are translated from the same mRNA. They share the same C-terminal DNA binding domain except LAP has an extra N-terminal activation domain. Probably due to its higher affinity for its DNA cognate sequences, LIP can inhibit LAP transcriptional activity even at substoichiometric levels. However, the regulatory mechanism of C/EBPß gene expression and the LAP: LIP ratio is unclear. METHODS: In this study, the C/EBPß promoter sequence was scanned for conserved P53 response element (P53RE), and binding of P53 to the C/EBPß promoter was tested by Electrophoretic Mobility Shift Assay (EMSA) and chromatin immunoprecipitation assay. P53 over-expression and dominant negative P53 expression plasmids were transfected into rat lung fibroblasts and tested for C/EBPß gene transcription and expression. Western blot analysis was used to test the regulation of C/EBPß LAP and LIP isoforms. Constructs containing the LAP 5'untranslated region (5'UTR) or the LIP 5'UTR region were used to test the importance of 5'UTR in the control of C/EBPß LAP and LIP translation. RESULTS: The C/EBPß promoter sequence was found to contain a conserved P53 response element (P53RE), which binds P53 as demonstrated by Electrophoresis Mobility Shift Assay and chromatin immunoprecipitation assays. P53 over-expression suppressed while dominant negative P53 stimulated C/EBPß gene transcription and expression. Western blot analysis showed that P53 differentially regulated the translation of the C/EBPß LAP and LIP isoforms through the regulation of eIF4E and eIF4E-BP1. Further studies with constructs containing the LAP 5'untranslated region (5'UTR) or the LIP 5'UTR region showed that the 5'UTR is important in differential control of C/EBPß LAP and LIP translation. CONCLUSION: Analysis of the effects of P53 on C/EBPß expression revealed a novel mechanism by which P53 could antagonize the effects of C/EBPß on its target gene expression. For the first time, P53 is shown to be a repressor of C/EBPß gene expression at both transcriptional and translational levels, with a differential effect in the magnitude of the effect on LAP vs. LIP isoforms.

Expression and Activity of the Transcription Factor CCAAT/Enhancer-Binding Protein ß (C/EBPß) Is Regulated by Specific Pulse-Modulated Radio Frequencies in Oligodendroglial Cells.

The rapid growth of wireless electronic devices has raised concerns about the harmful effects of leaked electromagnetic radiation (EMR) on human health. Even though numerous studies have been carried out to explore the biological effects of EMR, no clear conclusions have been drawn about the effect of radio frequency (RF) EMR on oligodendrocytes. To this end, we exposed oligodendroglia and three other types of brain cells to 2.4 GHz EMR for 6 or 48 h at an average input power of 1 W in either a continuous wave (CW-RF) or a pulse-modulated wave (PW-RF, 50 Hz pulse frequency, 1/3 duty cycle) pattern. RNA sequencing, RT-qPCR, and Western blot were used to examine the expression of C/EBPß and its related genes. Multiple reaction monitoring (MRM) was used to examine the levels of expression of C/EBPß-interacting proteins. Our results showed that PW-RF EMR significantly increased the mRNA level of C/EBPß in oligodendroglia but not in other types of cells. In addition, the expression of three isoforms and several interacting proteins and targeted genes of C/EBPß were markedly changed after 6-h PW-RF but not CW-RF. Our results indicated that RF EMR regulated the expression and functions of C/EBPß in a waveform- and cell-type-dependent manner.

C/EBPß deficiency enhances the keratinocyte innate immune response to direct activators of cytosolic pattern recognition receptors.

The skin is the first line of defense to cutaneous microbes and viruses, and epidermal keratinocytes play a critical role in preventing infection by viruses and pathogens through activation of the type I interferon (IFN) response. Using RNAseq analysis, here we report that the conditional deletion of C/EBPß transcription factor in mouse epidermis (CKOß mice) resulted in the upregulation of IFNß and numerous keratinocyte interferon-stimulated genes (ISGs). The expression of cytosolic pattern recognition receptors (cPRRs), that recognize viral RNA and DNA, were significantly increased, and enriched in the RNAseq data set. cPRRs stimulate a type I IFN response that can trigger cell death to eliminate infected cells. To determine if the observed increases in cPRRs had functional consequences, we transfected CKOß primary keratinocytes with the pathogen and viral mimics poly(I:C) (dsRNA) or poly(dA:dT) (synthetic B-DNA) that directly activate PRRs. Transfected CKOß primary keratinocytes displayed an amplified type I IFN response which was accompanied by increased activation of IRF3, enhanced ISG expression, enhanced activation of caspase-8, caspase-3 and increased apoptosis. Our results identify C/EBPß as a critical repressor of the keratinocyte type I IFN response, and demonstrates that the loss of C/EBPß primes keratinocytes to the activation of cytosolic PRRs by pathogen RNA and DNA to induce cell death mediated by caspase-8 and caspase-3.