BMP7 Ameliorated Viral Myocardial Fibrosis by Inhibiting Endothelial-to-Mesenchymal Transition

Abstract Background: Endothelial-to-mesenchymal transition (Endo-MT) is associated with myocardial fibrosis in dilated cardiomyopathy (DCM). Endothelial-to-mesenchymal transition (Endo-MT) is induced by coxsackievirus B3 (CVB3) in cardiac microvascular endothelial cells (CMVECs). Bone morphogenetic protein 7 (BMP7) significantly inhibits Endo-MT and the progression of cardiac fibrosis. The study was aimed to investigate the effect and the underlying mechanism of BMP7 on Endo-MT in myocardial fibrosis induce by CVB3 infection in vivo. Methods: BALB/c mice were intraperitoneally injected by CVB3 to induce viral myocarditis (VMC). Mice were treated with BMP7 after CVB3 infection. Subsequently, all groups of mice were determined by echocardiography, histopathologic and molecular detection. Results: We found that the ratio of BMP7/TGF-β1 in mRNA levels was decreased obviously at different time points after CVB3 injection. BMP7 facilitated the recovery of cardiac function after CVB3 infection via inhibition of myocardial damage, collagen deposition. Double immunofluorescence staining indicated that Endo-MT was implicated in CVB3-induced myocardial fibrosis, which was attenuated by BMP7. The protein levels of pSmad3 and Smad4 were significantly upregulated in VMC group, as well as Wnt/β-catenin and the transcription factor snail. BMP7 treatment reversed the changes of these protein levels. Moreover, CO-IP demonstrated the crosstalk between β-catenin and Smad3 in VMC mice, which was downregulated by BMP7 treatment. Conclusions: These results indicated that BMP7 obviously ameliorated myocardial fibrosis in CVB3-infected mice via Endo-MT, which was involved in the TGF-β/Smad and Wnt/β-catenin pathway. β-Catenin/Smad3 interaction may be associated with Endo-MT in the development of viral myocardial fibrosis.

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Calcitriol Attenuates Doxorubicin-Induced Cardiac Dysfunction and Inhibits Endothelial-to-Mesenchymal Transition in Mice

Cells ◽

10.3390/cells8080865 ◽

2019 ◽

Vol 8 (8) ◽

pp. 865 ◽

Cited By ~ 5

Author(s):

Tsai ◽

Lin ◽

Hang ◽

Chen

Keyword(s):

Myocardial Fibrosis ◽

Cardiac Fibrosis ◽

Transforming Growth Factor ◽

Cardiac Fibroblasts ◽

Umbilical Vein ◽

Active Form ◽

Mesenchymal Transition ◽

Endothelial To Mesenchymal Transition ◽

Umbilical Vein Endothelial Cells

Doxorubicin (Dox) is an effective anti-neoplasm drug, but its cardiac toxicity limits its clinical use. Endothelial-to-mesenchymal transition (EndMT) has been found to be involved in the process of heart failure. It is unclear whether EndMT contributes to Dox-induced cardiomyopathy (DoIC). Calcitriol, an active form Vitamin D3, blocks the growth of cancer cells by inhibiting the Smad pathway. To investigate the effect of calcitriol via inhibiting EndMT in DoIC, C57BL/6 mice and endothelial-specific labeled mice were intraperitoneally administered Dox twice weekly for 4 weeks (32 mg/kg cumulative dose) and were subsequently treated with or without calcitriol for 12 weeks. Echocardiography revealed diastolic dysfunction at 13 weeks following the first Dox treatment, accompanied by increased myocardial fibrosis and up-regulated pro-fibrotic proteins. Calcitriol attenuated Dox-induced myocardial fibrosis, down-regulated pro-fibrotic proteins and improved diastolic function. Endothelial fate tracing revealed that EndMT-derived cells contributed to Dox-induced cardiac fibrosis. In vitro, human umbilical vein endothelial cells and mouse cardiac fibroblasts were treated with Transforming growth factor (TGF)-β with or without calcitriol. Morphological, immunofluorescence staining, and Western blot analyses revealed that TGF-β-induced EndMT and fibroblast-to-myofibroblast transition (FMT) were attenuated by calcitriol by the inhibition of the Smad2 pathway. Collectively, calcitriol attenuated DoIC through the inhibition of the EndMT and FMT processes.

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P3115Effect of calcitriol attenuates doxorubicin-induced cardiac dysfunction in mice model: focus on endothelial-to-mesenchymal transition

European Heart Journal ◽

10.1093/eurheartj/ehz745.0190 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

T H Tsai ◽

W Y Chen

Keyword(s):

Heart Failure ◽

Endothelial Cells ◽

Myocardial Fibrosis ◽

Cardiac Fibrosis ◽

Cardiac Myocyte ◽

Cell Damage ◽

Active Form ◽

Smad Pathway ◽

Mesenchymal Transition ◽

Endothelial To Mesenchymal Transition

Abstract Objective Doxorubicin (DOX) is an effective anti-neoplasm drug, but the early and late cardiac toxicity limits its clinical use. The Endothelial-to-mesenchymal transition (EndMT) has been found to involve in the process of heart failure. It's unclear whether EndMT plays a role in DOX-induced cardiomyopathy (DoIC). Calcitriol is an active form Vitamin D3, which blocks the growth of cancer cells via inhibiting Smad pathway. This study investigated the cardiac protective effect of calcitriol via inhibiting of EndMT in DoIC. Methods/Findings C57BL/6 mice and endothelial-specific labeled mice were administered Dox twice weekly for 4 weeks [intraperitoneally (i.p.), 32 mg/kg cumulative dose]and were subsequently treated with/without calcitriol for 12 weeks. The cardiac echography revealed diastolic dysfunction at 13 weeks following the first DOX treatment and was accompanied by increased of myocardial fibrosis and up-regulated pro-fibrotic proteins.(Figure A-C) Calcitriol attenuated DOX-induced myocardial fibrosis, down-regulated pro-fibrotic proteinsand diastolic function. Endothelial fate tracing revealed that endothelium-derived cells contributed DOX-induced cardiac remodelling through EndMT and Calcitriol attenuated this process without attenuating Dox-induced cardiac myocyte and endothelial cell damage.(Figure D) In vitro, we examined if calcitriol would inhibit EndMT and fibroblast-to-myofibroblast transition (FMT) through the Smad pathway. Human umbilical vein endothelial cells (HUVECs) and mouse cardiac fibroblasts were treated with TGF-beta with or without calcitriol. Morphological, immunofluorescence staining, and western blot analyses were carried out to evaluate EndMT and FMT. Calcitriol attenuated EndMT and FMT by inhibiting the Smad2 pathway. Taken together, calcitriol didn't reduced Doxorubicin induced damage of cardiomocyte and endothelial cells. But calcitriol inhibit doxorubicin induced heart failure by attenuating cardiac fibrosis through inhibiting Smad pathway. Conclusion Calcitriol attenuated DOX-induced cardiomyopathy partial through inhibiting EndMT process. Acknowledgement/Funding CMRPG8E0661-3

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Proteasome inhibition attenuates coxsackievirus-induced myocardial damage in mice

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00292.2008 ◽

2008 ◽

Vol 295 (1) ◽

pp. H401-H408 ◽

Cited By ~ 38

Author(s):

Guang Gao ◽

Jingchun Zhang ◽

Xiaoning Si ◽

Jerry Wong ◽

Caroline Cheung ◽

...

Keyword(s):

Proteasome Inhibitor ◽

Critical Role ◽

Plaque Assay ◽

Viral Myocarditis ◽

Myocardial Damage ◽

Proteasome Inhibition ◽

Cvb3 Infection ◽

In Vivo Animal Model

Coxsackievirus B3 (CVB3) is one of the most prevalent pathogens of viral myocarditis, which may persist chronically and progress to dilated cardiomyopathy. We previously demonstrated a critical role of the ubiquitin-proteasome system (UPS) in the regulation of coxsackievirus replication in mouse cardiomyocytes. In the present study, we extend our interest to an in vivo animal model to examine the regulation and role of the UPS in CVB3-induced murine myocarditis. Male myocarditis-susceptible A/J mice at age 4–5 wk were randomized to four groups: sham infection + vehicle ( n = 10), sham infection + proteasome inhibitor ( n = 10), virus + vehicle ( n = 20), and virus + proteasome inhibitor ( n = 20). Proteasome inhibitor was administered subcutaneously once a day for 3 days. Mice were killed on day 9 after infection, and infected hearts were harvested for Western blot analysis, plaque assay, immunostaining, and histological examination. We showed that CVB3 infection led to an accumulation of ubiquitin conjugates at 9 days after infection. Protein levels of ubiquitin-activating enzyme E1A/E1B, ubiquitin-conjugating enzyme UBCH7, as well as deubiquitinating enzyme UCHL1 were markedly increased in CVB3-infected mice compared with sham infection. However, there was no significant alteration in proteasome activities at 9 days after infection. Immunohistochemical staining revealed that increased expression of E1A/E1B was mainly localized to virus-damaged cells. Finally, we showed that application of a proteasome inhibitor significantly reduced CVB3-induced myocardial damage. This observation reveals a novel mechanism of coxsackieviral pathogenesis, and suggests that the UPS may be an attractive therapeutic target against coxsackievirus-induced myocarditis.

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Abstract MP02: Angiotensin II Mediates Microvascular Rarefaction In Vivo and Exacerbates Endothelial-To-Mesenchymal Transition In Vitro

Hypertension ◽

10.1161/hyp.66.suppl_1.mp02 ◽

2015 ◽

Vol 66 (suppl_1) ◽

Author(s):

Katrin Nather ◽

Mónica Flores-Muñoz ◽

Rhian M Touyz ◽

Christopher M Loughrey ◽

Stuart A Nicklin

Keyword(s):

Endothelial Cells ◽

Smooth Muscle ◽

Cardiac Fibrosis ◽

Smooth Muscle Actin ◽

Muscle Actin ◽

Mesenchymal Transition ◽

Endothelial To Mesenchymal Transition

Cardiac fibrosis accompanies numerous cardiovascular diseases (CVD) such as hypertension and myocardial infarction and increases myocardial stiffness leading to contractile dysfunction. Recently, endothelial-to-mesenchymal transition (EndMT) has been shown to contribute to myocardial fibrosis. EndMT describes a process by which endothelial cells transform into mesenchymal cells such as fibroblasts and has been implicated in many fibrotic diseases. Angiotensin II (AngII) plays a key role in myocardial fibrosis and has been associated with the activation of fibroblasts to myofibroblasts and an increase in myocardial collagen deposition. Here, we assessed the role of AngII in capillary loss and EndMT in vivo and in vitro . C57BL/6J mice were infused with H 2 O (control) or 24μg/kg/hr AngII for 4 weeks. Mice infused with AngII developed significant cardiac fibrosis characterised by the deposition of collagen I (2.5-fold vs. control; p<0.05) and III (1.9-fold vs. control; p<0.05). Capillary density was assessed by CD31 immunohistochemistry and revealed significant vascular rarefaction (control 2161±111 vs . AngII 838±132 capillaries/mm 2 ; p<0.05). To investigate whether AngII can induce EndMT in vitro , human coronary artery endothelial cells were stimulated with 10ng/mL TGFβ 1 alone or in combination with 1μM AngII for 10 days. AngII significantly enhanced TGFβ 1 -induced gene expression of α-smooth muscle actin (TGFβ 1 1.8-fold; TGFβ 1 ±AngII 4.3-fold vs . control; p<0.05) and collagen I (TGFβ 1 9.2-fold; TGFβ 1 +AngII 30.2-fold vs . control; p<0.05). Concomitantly, AngII significantly increased α-smooth muscle actin protein expression (TGFβ 1 3.9-fold; TGFβ 1 +AngII 23.6-fold vs . control; p<0.05) and significantly decreased CD31 expression (TGFβ 1 0.9-fold; TGFβ 1 +AngII 0.7-fold vs . control; p<0.05), suggesting AngII acts in concert with TGFβ 1 to enhance conversion of endothelial cells to myofibroblasts. Further studies investigating the underlying mechanism, including the role of the Smad pathway, are ongoing. These results demonstrate that AngII induces vascular rarefaction in vivo and potentiates TGFβ 1 -induced EndMT in vitro. Understanding the molecular basis for these observations may help to identify new therapeutic options in CVD.

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Knockout RAGE alleviates cardiac fibrosis through repressing endothelial-to-mesenchymal transition (EndMT) mediated by autophagy

Cell Death and Disease ◽

10.1038/s41419-021-03750-4 ◽

2021 ◽

Vol 12 (5) ◽

Author(s):

Lu Zhang ◽

Jiaqi He ◽

Junyan Wang ◽

Jing Liu ◽

Zixin Chen ◽

...

Keyword(s):

Therapeutic Strategy ◽

Cardiac Fibrosis ◽

Smooth Muscle Actin ◽

Heart Tissue ◽

Mesenchymal Transition ◽

Glycation End Products ◽

Endothelial To Mesenchymal Transition ◽

Related Proteins

AbstractEndothelial-to-mesenchymal transition (EndMT) has been shown to contribute to cardiac fibrosis and heart failure (HF). Recent studies have demonstrated that EndMT is regulated by autophagy, and we previously showed suppression of excessive autophagy and alleviation of cardiac fibrosis in HF mice with inactivated receptor for advanced glycation end products (RAGE). Thus, we investigated whether reduced cardiac fibrosis due to RAGE knockout occurred by inhibiting EndMT mediated by excessive autophagy. We found a decrease in endothelial cells (CD31+/VE-Cadherin+) and an increase in cells co-expressing CD31 and α-smooth muscle actin (α-SMA, myofibroblast marker) at 8 weeks in heart tissue of mice subjected to transverse aortic constriction (TAC), which implied EndMT. Knockout RAGE decreased EndMT accompanied by decreased expression of autophagy-related proteins (LC3BII/I and Beclin 1), and alleviated cardiac fibrosis and improved cardiac function in TAC mice. Moreover, 3-methyladenine (3-MA) and chloroquine (CQ), inhibitors of autophagy, attenuated EndMT, and cardiac fibrosis in TAC mice. Importantly, EndMT induced by AGEs could be blocked by autophagy inhibitor in vivo and in vitro. These results suggested that AGEs/RAGE-autophagy-EndMT axis involved in the development of cardiac fibrosis and knockout RAGE ameliorated cardiac fibrosis through decreasing EndMT regulated by autophagy, which could be a promising therapeutic strategy for HF.

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TRIM27 interacts with Iκbα to promote the growth of human renal cancer cells through regulating the NF-κB pathway

BMC Cancer ◽

10.1186/s12885-021-08562-5 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Chengwu Xiao ◽

Wei Zhang ◽

Meimian Hua ◽

Huan Chen ◽

Bin Yang ◽

...

Keyword(s):

Cell Lines ◽

Prognostic Indicator ◽

The Cancer Genome Atlas ◽

Mrna Levels ◽

Loss Of Function ◽

Protein Levels ◽

Kaplan Meier ◽

Cancer Genome Atlas

Abstract Background The tripartite motif (TRIM) family proteins exhibit oncogenic roles in various cancers. The roles of TRIM27, a member of the TRIM super family, in renal cell carcinoma (RCC) remained unexplored. In the current study, we aimed to investigate the clinical impact and roles of TRIM27 in the development of RCC. Methods The mRNA levels of TRIM27 and Kaplan–Meier survival of RCC were analyzed from The Cancer Genome Atlas database. Real-time PCR and Western blotting were used to measure the mRNA and protein levels of TRIM27 both in vivo and in vitro. siRNA and TRIM27 were exogenously overexpressed in RCC cell lines to manipulate TRIM27 expression. Results We discovered that TRIM27 was elevated in RCC patients, and the expression of TRIM27 was closely correlated with poor prognosis. The loss of function and gain of function results illustrated that TRIM27 promotes cell proliferation and inhibits apoptosis in RCC cell lines. Furthermore, TRIM27 expression was positively associated with NF-κB expression in patients with RCC. Blocking the activity of NF-κB attenuated the TRIM27-mediated enhancement of proliferation and inhibition of apoptosis. TRIM27 directly interacted with Iκbα, an inhibitor of NF-κB, to promote its ubiquitination, and the inhibitory effects of TRIM27 on Iκbα led to NF-κB activation. Conclusions Our results suggest that TRIM27 exhibits an oncogenic role in RCC by regulating NF-κB signaling. TRIM27 serves as a specific prognostic indicator for RCC, and strategies targeting the suppression of TRIM27 function may shed light on future therapeutic approaches.

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YAP1 Overexpression Is Associated with Kidney Dysfunction in Lupus Nephritis

Pathobiology ◽

10.1159/000517575 ◽

2021 ◽

pp. 1-12

Author(s):

Ying Xie ◽

Yuanyuan Ruan ◽

Huimei Zou ◽

Yixin Wang ◽

Xin Wu ◽

...

Keyword(s):

Lupus Nephritis ◽

Epithelial Mesenchymal Transition ◽

Kidney Tissue ◽

Mouse Kidney ◽

Experimental Comparison ◽

Control Group ◽

Mrna Levels ◽

Mesenchymal Transition ◽

Protein Levels

Objective: The goal of the present study was to determine the expression of yes-associated protein 1 (YAP1) in renal tissues of mice with lupus nephritis (LN) and elucidate its role in the progression of renal fibrosis. Methods: C57BL/6 mice and MRL/lpr mice were selected for experimental comparison. Mouse kidney tissues were removed and sectioned for hematoxylin and eosin staining, Masson’s trichome staining, Sirius staining, and immunohistochemistry. The mRNA and protein levels of YAP1 in mouse kidney tissues were detected, and the correlation between YAP1 and fibronectin (FN) mRNA levels was analyzed. Mouse renal epithelial cells were used for in vitro experiments. After transfection and stimulation, the cells were divided into 4 groups, namely the C57BL/6 serum group (group 1), the MRL/lpr serum group (group 2), the MRL/lpr serum + siRNA-negative control group (group 3), and the MRL/lpr serum + siRNA-YAP1 group (group 4). Epithelial-mesenchymal transition (EMT) markers in each group were detected by Western blotting and immunofluorescence staining. Serum creatinine, blood urea nitrogen, and urinary protein levels were detected and assessed for their correlation with YAP1 mRNA levels by Spearman’s analysis. Results: Compared to C57BL/6 mice, MRL/lpr mice exhibited obvious changes in fibrosis in renal tissues. In addition, YAP1 expression was significantly higher in the renal tissues of MRL/lpr mice than in those of C57BL/6 mice, and YAP1 mRNA levels were positively correlated with those of FN. YAP1 silencing in lupus serum-stimulated cells could effectively relieve serum-induced EMT. Finally, we observed that YAP1 mRNA levels in mouse kidney tissue were significantly and positively correlated with the degree of renal function injury. Conclusion: YAP1 expression in the kidney tissues of LN mice was higher than that observed in normal mice, indicating that YAP1 may play an important role in the occurrence and development of LN.

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EXTH-51. ANTI-INVASIVE EFFICACY AND SURVIVAL BENEFIT OF THE YAP-TEAD INHIBITOR VERTEPORFIN IN PRECLINICAL GLIOBLASTOMA MODELS

Neuro-Oncology ◽

10.1093/neuonc/noaa215.405 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii98-ii98

Author(s):

Anne Marie Barrette ◽

Alexandros Bouras ◽

German Nudelman ◽

Zarmeen Mussa ◽

Elena Zaslavsky ◽

...

Keyword(s):

Survival Benefit ◽

De Novo ◽

Epithelial Mesenchymal Transition ◽

Intraperitoneal Administration ◽

Standard Of Care ◽

Tumor Burden ◽

Mesenchymal Transition ◽

Protein Levels

Abstract Glioblastoma (GBM) remains an incurable disease, in large part due to its malignant infiltrative spread, and current clinical therapy fails to target the invasive nature of tumor cells in disease progression and recurrence. Here, we use the YAP-TEAD inhibitor Verteporfin to target a convergence point for regulating tumor invasion/metastasis and establish the robust anti-invasive therapeutic efficacy of this FDA-approved drug and its survival benefit across several preclinical glioma models. Using patient-derived GBM cells and orthotopic xenograft models (PDX), we show that Verteporfin treatment disrupts YAP/TAZ-TEAD activity and processes related to cell adhesion, migration and epithelial-mesenchymal transition. In-vitro, Verteporfin impairs tumor migration, invasion and motility dynamics. In-vivo, intraperitoneal administration of Verteporfin in mice with orthotopic PDX tumors shows consistent drug accumulation within the brain and decreased infiltrative tumor burden, across three independent experiments. Interestingly, PDX tumors with impaired invasion after Verteporfin treatment downregulate CDH2 and ITGB1 adhesion protein levels within the tumor microenvironment. Finally, Verteporfin treatment confers survival benefit in two independent PDX models: as monotherapy in de-novo GBM and in combination with standard-of-care chemoradiation in recurrent GBM. These findings indicate potential therapeutic value of this FDA-approved drug if repurposed for GBM patients.

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Endothelial-to-Mesenchymal Transition in Human Adipose Tissue Vasculature Alters the Particulate Secretome and Induces Endothelial Dysfunction

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvbaha.119.312826 ◽

2019 ◽

Vol 39 (10) ◽

pp. 2168-2191 ◽

Cited By ~ 3

Author(s):

Bronson A. Haynes ◽

Li Fang Yang ◽

Ryan W. Huyck ◽

Eric J. Lehrer ◽

Joshua M. Turner ◽

...

Keyword(s):

Adipose Tissue ◽

Endothelial Dysfunction ◽

Smooth Muscle Actin ◽

Phenotypic Change ◽

Alpha Smooth Muscle Actin ◽

Mesenchymal Transition ◽

Molecular Features ◽

Endothelial To Mesenchymal Transition

Objective: Endothelial cells (EC) in obese adipose tissue (AT) are exposed to a chronic proinflammatory environment that may induce a mesenchymal-like phenotype and altered function. The objective of this study was to establish whether endothelial-to-mesenchymal transition (EndoMT) is present in human AT in obesity and to investigate the effect of such transition on endothelial function and the endothelial particulate secretome represented by extracellular vesicles (EV). Approach and Results: We identified EndoMT in obese human AT depots by immunohistochemical co-localization of CD31 or vWF and α-SMA (alpha-smooth muscle actin). We showed that AT EC exposed in vitro to TGF-β (tumor growth factor-β), TNF-α (tumor necrosis factor-α), and IFN-γ (interferon-γ) undergo EndoMT with progressive loss of endothelial markers. The phenotypic change results in failure to maintain a tight barrier in culture, increased migration, and reduced angiogenesis. EndoMT also reduced mitochondrial oxidative phosphorylation and glycolytic capacity of EC. EVs produced by EC that underwent EndoMT dramatically reduced angiogenic capacity of the recipient naïve ECs without affecting their migration or proliferation. Proteomic analysis of EV produced by EC in the proinflammatory conditions showed presence of several pro-inflammatory and immune proteins along with an enrichment in angiogenic receptors. Conclusions: We demonstrated the presence of EndoMT in human AT in obesity. EndoMT in vitro resulted in production of EV that transferred some of the functional and metabolic features to recipient naïve EC. This result suggests that functional and molecular features of EC that underwent EndoMT in vivo can be disseminated in a paracrine or endocrine fashion and may induce endothelial dysfunction in distant vascular beds.

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DBC1 (Deleted in Breast Cancer 1) modulates the stability and function of the nuclear receptor Rev-erbα

Biochemical Journal ◽

10.1042/bj20121085 ◽

2013 ◽

Vol 451 (3) ◽

pp. 453-461 ◽

Cited By ~ 26

Author(s):

Claudia C. S. Chini ◽

Carlos Escande ◽

Veronica Nin ◽

Eduardo N. Chini

Keyword(s):

Breast Cancer ◽

Nuclear Receptor ◽

Clock Genes ◽

Mrna Levels ◽

Protein Levels ◽

The Stability ◽

And Function ◽

Interfering Rna ◽

In Cells

The nuclear receptor Rev-erbα has been implicated as a major regulator of the circadian clock and integrates circadian rhythm and metabolism. Rev-erbα controls circadian oscillations of several clock genes and Rev-erbα protein degradation is important for maintenance of the circadian oscillations and also for adipocyte differentiation. Elucidating the mechanisms that regulate Rev-erbα stability is essential for our understanding of these processes. In the present paper, we report that the protein DBC1 (Deleted in Breast Cancer 1) is a novel regulator of Rev-erbα. Rev-erbα and DBC1 interact in cells and in vivo, and DBC1 modulates the Rev-erbα repressor function. Depletion of DBC1 by siRNA (small interfering RNA) in cells or in DBC1-KO (knockout) mice produced a marked decrease in Rev-erbα protein levels, but not in mRNA levels. In contrast, DBC1 overexpression significantly enhanced Rev-erbα protein stability by preventing its ubiquitination and degradation. The regulation of Rev-erbα protein levels and function by DBC1 depends on both the N-terminal and C-terminal domains of DBC1. More importantly, in cells depleted of DBC1, there was a dramatic decrease in circadian oscillations of both Rev-erbα and BMAL1. In summary, our data identify DBC1 as an important regulator of the circadian receptor Rev-erbα and proposes that Rev-erbα could be involved in mediating some of the physiological effects of DBC1.

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