scholarly journals LXRα Regulates ChREBPα Transactivity in a Target Gene-Specific Manner through an Agonist-Modulated LBD-LID Interaction

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1214
Author(s):  
Qiong Fan ◽  
Rikke Christine Nørgaard ◽  
Ivar Grytten ◽  
Cecilie Maria Ness ◽  
Christin Lucas ◽  
...  
Keyword(s):  
Target Genes ◽  
Binding Capacity ◽  
Quantitative Polymerase Chain Reaction ◽  
Glucose Sensing ◽  
Activation Domains ◽  
Specific Target ◽  
Glucose And Lipid Metabolism ◽  
Element Binding Protein

The cholesterol-sensing nuclear receptor liver X receptor (LXR) and the glucose-sensing transcription factor carbohydrate responsive element-binding protein (ChREBP) are central players in regulating glucose and lipid metabolism in the liver. More knowledge of their mechanistic interplay is needed to understand their role in pathological conditions like fatty liver disease and insulin resistance. In the current study, LXR and ChREBP co-occupancy was examined by analyzing ChIP-seq datasets from mice livers. LXR and ChREBP interaction was determined by Co-immunoprecipitation (CoIP) and their transactivity was assessed by real-time quantitative polymerase chain reaction (qPCR) of target genes and gene reporter assays. Chromatin binding capacity was determined by ChIP-qPCR assays. Our data show that LXRα and ChREBPα interact physically and show a high co-occupancy at regulatory regions in the mouse genome. LXRα co-activates ChREBPα and regulates ChREBP-specific target genes in vitro and in vivo. This co-activation is dependent on functional recognition elements for ChREBP but not for LXR, indicating that ChREBPα recruits LXRα to chromatin in trans. The two factors interact via their key activation domains; the low glucose inhibitory domain (LID) of ChREBPα and the ligand-binding domain (LBD) of LXRα. While unliganded LXRα co-activates ChREBPα, ligand-bound LXRα surprisingly represses ChREBPα activity on ChREBP-specific target genes. Mechanistically, this is due to a destabilized LXRα:ChREBPα interaction, leading to reduced ChREBP-binding to chromatin and restricted activation of glycolytic and lipogenic target genes. This ligand-driven molecular switch highlights an unappreciated role of LXRα in responding to nutritional cues that was overlooked due to LXR lipogenesis-promoting function.

scholarly journals Open the LID: LXRα regulates ChREBPα transactivity in a target gene-specific manner through an agonist-modulated LBD-LID interaction

2019 ◽  
Author(s):  
Qiong Fan ◽  
Rikke C. Nørgaard ◽  
Ivar Grytten ◽  
Cecilie M. Ness ◽  
Christin Lucas ◽  
...  
Keyword(s):  
Target Genes ◽  
Glucose Sensing ◽  
Activation Domains ◽  
Specific Target ◽  
Glucose And Lipid Metabolism ◽  
Element Binding Protein ◽  
Underlying Mechanisms ◽  
Responsive Element

ABSTRACTThe cholesterol-sensing nuclear receptor liver X receptor (LXR) and the glucose-sensing transcription factor carbohydrate responsive element-binding protein (ChREBP) are central players in regulating glucose and lipid metabolism in liver. We have previously shown that LXR regulates ChREBP transcription and activity; however, the underlying mechanisms are unclear. In the current study, we demonstrate that LXRα and ChREBPα interact physically, and show a high co-occupancy at regulatory regions in the mouse genome. LXRα co-activates ChREBPα, and regulates ChREBP-specific target genes in vitro and in vivo. This co-activation is dependent on functional recognition elements for ChREBP, but not for LXR, indicating that ChREBPα recruits LXRα to chromatin in trans. The two factors interact via their key activation domains; ChREBPα’s low glucose inhibitory domain (LID) and the ligand-binding domain (LBD) of LXRα. While unliganded LXRα co-activates ChREBPα, ligand-bound LXRα surprisingly represses ChREBPα activity on ChREBP-specific target genes. Mechanistically, this is due to a destabilized LXRα:ChREBPα interaction, leading to reduced ChREBP-binding to chromatin and restricted activation of glycolytic and lipogenic target genes. This ligand-driven molecular switch highlights an unappreciated role of LXRα that was overlooked due to LXR lipogenesis-promoting function.

scholarly journals A New Role for Sterol Regulatory Element Binding Protein 1 Transcription Factors in the Regulation of Muscle Mass and Muscle Cell Differentiation

2009 ◽  
Vol 30 (5) ◽  
pp. 1182-1198 ◽  
Author(s):  
Virginie Lecomte ◽  
Emmanuelle Meugnier ◽  
Vanessa Euthine ◽  
Christine Durand ◽  
Damien Freyssenet ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Muscle Mass ◽  
Target Genes ◽  
Binding Protein ◽  
Regulatory Element ◽  
Element Binding Protein ◽  
Sterol Regulatory Element ◽  
Myogenic Program

ABSTRACT The role of the transcription factors sterol regulatory element binding protein 1a (SREBP-1a) and SREBP-1c in the regulation of cholesterol and fatty acid metabolism has been well studied; however, little is known about their specific function in muscle. In the present study, analysis of recent microarray data from muscle cells overexpressing SREBP1 suggested that they may play a role in the regulation of myogenesis. We then demonstrated that SREBP-1a and -1c inhibit myoblast-to-myotube differentiation and also induce in vivo and in vitro muscle atrophy. Furthermore, we have identified the transcriptional repressors BHLHB2 and BHLHB3 as mediators of these effects of SREBP-1a and -1c in muscle. Both repressors are SREBP-1 target genes, and they affect the expression of numerous genes involved in the myogenic program. Our findings identify a new role for SREBP-1 transcription factors in muscle, thus linking the control of muscle mass to metabolic pathways.

scholarly journals cAMP-Responsive Element Binding Protein: A Vital Link in Embryonic Hormonal Adaptation

Endocrinology ◽  
2013 ◽  
Vol 154 (6) ◽  
pp. 2208-2221 ◽  
Author(s):  
Maria Schindler ◽  
Sünje Fischer ◽  
René Thieme ◽  
Bernd Fischer ◽  
Anne Navarrete Santos
Keyword(s):  
Transcription Factors ◽  
Target Genes ◽  
Binding Protein ◽  
Cell Lineage ◽  
Element Binding Protein ◽  
A Cell ◽  
Responsive Element ◽  
Camp Responsive Element Binding

Abstract The transcription factor cAMP responsive element-binding protein (CREB) and activating transcription factors (ATFs) are downstream components of the insulin/IGF cascade, playing crucial roles in maintaining cell viability and embryo survival. One of the CREB target genes is adiponectin, which acts synergistically with insulin. We have studied the CREB-ATF-adiponectin network in rabbit preimplantation development in vivo and in vitro. From the blastocyst stage onwards, CREB and ATF1, ATF3, and ATF4 are present with increasing expression for CREB, ATF1, and ATF3 during gastrulation and with a dominant expression in the embryoblast (EB). In vitro stimulation with insulin and IGF-I reduced CREB and ATF1 transcripts by approximately 50%, whereas CREB phosphorylation was increased. Activation of CREB was accompanied by subsequent reduction in adiponectin and adiponectin receptor (adipoR)1 expression. Under in vivo conditions of diabetes type 1, maternal adiponectin levels were up-regulated in serum and endometrium. Embryonic CREB expression was altered in a cell lineage-specific pattern. Although in EB cells CREB localization did not change, it was translocated from the nucleus into the cytosol in trophoblast (TB) cells. In TB, adiponectin expression was increased (diabetic 427.8 ± 59.3 pg/mL vs normoinsulinaemic 143.9 ± 26.5 pg/mL), whereas it was no longer measureable in the EB. Analysis of embryonic adipoRs showed an increased expression of adipoR1 and no changes in adipoR2 transcription. We conclude that the transcription factors CREB and ATFs vitally participate in embryo-maternal cross talk before implantation in a cell lineage-specific manner. Embryonic CREB/ATFs act as insulin/IGF sensors. Lack of insulin is compensated by a CREB-mediated adiponectin expression, which may maintain glucose uptake in blastocysts grown in diabetic mothers.

scholarly journals Dietary Fiber: An Opportunity for a Global Control of Hyperlipidemia

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Ying Nie ◽  
Feijun Luo
Keyword(s):  
Dietary Fiber ◽  
Target Genes ◽  
Binding Capacity ◽  
Protective Action ◽  
Underlying Mechanism ◽  
Mapk Signaling ◽  
Lipid Lowering ◽  
Dietary Fibers

Dietary fiber has a long history in the intervention study of hyperlipidemia. In this review, current understandings of structures, sources, and natures of various kinds of dietary fibers (DFs) were analyzed first. Available evidences for the use of different varieties of DFs in the lipid-lowering action both in vitro and in vivo were subsequently classified, including both soluble ones, such as glucans, pectins, and gums, and insoluble ones, including arabinooxylans and chitosans, in order to draw a primary conclusion of their dose and molecular weight relationship with lipid-lowering effect. Their potential mechanisms, especially the related molecular mechanism of protective action in the treatment and prevention of hyperlipidemia, were summarized at last. Five major mechanisms are believed to be responsible for the antihyperlipidemic benefits of DFs, including low levels of energy, bulking effect, viscosity, binding capacity, and fermentation thus ameliorating the symptoms of hyperlipidemia. From the molecular level, DFs could possibly affect the activities of HMG-CoA reductase, LDL receptors, CYP7A1, and MAPK signaling pathway as well as other lipid metabolism-related target genes. In summary, dietary fibers could be used as alternative supplements to exert certain lipid-lowering effects on humans. However, more clinical evidence is needed to strengthen this proposal and its fully underlying mechanism still requires more investigation.

scholarly journals Cell-specific discrimination of desmosterol and desmosterol mimetics confers selective regulation of LXR and SREBP in macrophages

2018 ◽  
Vol 115 (20) ◽  
pp. E4680-E4689 ◽  
Author(s):  
Evan D. Muse ◽  
Shan Yu ◽  
Chantle R. Edillor ◽  
Jenhan Tao ◽  
Nathanael J. Spann ◽  
...  
Keyword(s):  
Target Genes ◽  
Fatty Acid Biosynthesis ◽  
Regulatory Element ◽  
Element Binding Protein ◽  
Cholesterol Biosynthetic Pathway ◽  
Sterol Regulatory Element ◽  
X Receptors ◽  
Lxr Agonists

Activation of liver X receptors (LXRs) with synthetic agonists promotes reverse cholesterol transport and protects against atherosclerosis in mouse models. Most synthetic LXR agonists also cause marked hypertriglyceridemia by inducing the expression of sterol regulatory element-binding protein (SREBP)1c and downstream genes that drive fatty acid biosynthesis. Recent studies demonstrated that desmosterol, an intermediate in the cholesterol biosynthetic pathway that suppresses SREBP processing by binding to SCAP, also binds and activates LXRs and is the most abundant LXR ligand in macrophage foam cells. Here we explore the potential of increasing endogenous desmosterol production or mimicking its activity as a means of inducing LXR activity while simultaneously suppressing SREBP1c-induced hypertriglyceridemia. Unexpectedly, while desmosterol strongly activated LXR target genes and suppressed SREBP pathways in mouse and human macrophages, it had almost no activity in mouse or human hepatocytes in vitro. We further demonstrate that sterol-based selective modulators of LXRs have biochemical and transcriptional properties predicted of desmosterol mimetics and selectively regulate LXR function in macrophages in vitro and in vivo. These studies thereby reveal cell-specific discrimination of endogenous and synthetic regulators of LXRs and SREBPs, providing a molecular basis for dissociation of LXR functions in macrophages from those in the liver that lead to hypertriglyceridemia.

In Vitro and in Vivo Comparison of Binding of 99m-Tc-Iabeled Anti-CEA MAb F33-104 with 99m-Tc-labeled Anti-CEA MAb BW431/26

1999 ◽  
Vol 38 (04) ◽  
pp. 115-119
Author(s):  
N. Oriuchi ◽  
S. Sugiyama ◽  
M. Kuroki ◽  
Y. Matsuoka ◽  
S. Tanada ◽  
...  
Keyword(s):  
Nude Mice ◽  
Binding Capacity ◽  
Colon Adenocarcinoma ◽  
Human Colon ◽  
Cell Binding ◽  
Vitro Binding ◽  
Labeling Method ◽  
Human Colon Adenocarcinoma

Summary Aim: The purpose of this study was to assess the potential for radioimmunodetection (RAID) of murine anti-carcinoembryonic antigen (CEA) monoclonal antibody (MAb) F33-104 labeled with technetium-99m (99m-Tc) by a reduction-mediated labeling method. Methods: The binding capacity of 99m-Tc-labeled anti-CEA MAb F33-104 with CEA by means of in vitro procedures such as immunoradiometric assay and cell binding assay and the biodistribution of 99m-Tc-labeled anti-CEA MAb F33-104 in normal nude mice and nude mice bearing human colon adenocarcinoma LS180 tumor were investigated and compared with 99m-Tc-labeled anti-CEA MAb BW431/26. Results: The in vitro binding rate of 99m-Tc-labeled anti-CEA MAb F33-104 with CEA in solution and attached to the cell membrane was significantly higher than 99m-Tclabeled anti-CEA MAb BW431/261 (31.4 ± 0.95% vs. 11.9 ± 0.55% at 100 ng/mL of soluble CEA, 83.5 ± 2.84% vs. 54.0 ± 2.54% at 107 of LS 180 cells). In vivo, accumulation of 99m-Tc-labeled anti-CEA MAb F33-104 was higher at 18 h postinjection than 99m-Tc-labeled anti-CEA MAb BW431/26 (20.1 ± 3.50% ID/g vs. 14.4 ± 3.30% ID/g). 99m-Tcactivity in the kidneys of nude mice bearing tumor was higher at 18 h postinjection than at 3 h (12.8 ± 2.10% ID/g vs. 8.01 ± 2.40% ID/g of 99m-Tc-labeled anti-CEA MAb F33-104, 10.7 ± 1.70% ID/g vs. 8.10 ± 1.75% ID/g of 99m-Tc-labeled anti-CEA MAb BW431/26). Conclusion: 99m-Tc-labeled anti-CEA MAb F33-104 is a potential novel agent for RAID of recurrent colorectal cancer.

scholarly journals Circular RNA circSDHC serves as a sponge for miR-127-3p to promote the proliferation and metastasis of renal cell carcinoma via the CDKN3/E2F1 axis

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Junjie Cen ◽  
Yanping Liang ◽  
Yong Huang ◽  
Yihui Pan ◽  
Guannan Shu ◽  
...  
Keyword(s):  
Renal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Renal Cell ◽  
Target Genes ◽  
Expression Patterns ◽  
Luciferase Reporter ◽  
Circular Rnas ◽  
Proliferation And Metastasis

Abstract Background There is increasing evidence that circular RNAs (circRNAs) have significant regulatory roles in cancer development and progression; however, the expression patterns and biological functions of circRNAs in renal cell carcinoma (RCC) remain largely elusive. Method Bioinformatics methods were applied to screen for circRNAs differentially expressed in RCC. Analysis of online circRNAs microarray datasets and our own patient cohort indicated that circSDHC (hsa_circ_0015004) had a potential oncogenic role in RCC. Subsequently, circSDHC expression was measured in RCC tissues and cell lines by qPCR assay, and the prognostic value of circSDHC evaluated. Further, a series of functional in vitro and in vivo experiments were conducted to assess the effects of circSDHC on RCC proliferation and metastasis. RNA pull-down assay, luciferase reporter and fluorescent in situ hybridization assays were used to confirm the interactions between circSDHC, miR-127-3p and its target genes. Results Clinically, high circSDHC expression was correlated with advanced TNM stage and poor survival in patients with RCC. Further, circSDHC promoted tumor cell proliferation and invasion, both in vivo and in vitro. Analysis of the mechanism underlying the effects of circSDHC in RCC demonstrated that it binds competitively to miR-127-3p and prevents its suppression of a downstream gene, CDKN3, and the E2F1 pathway, thereby leading to RCC malignant progression. Furthermore, knockdown of circSDHC caused decreased CDKN3 expression and E2F1 pathway inhibition, which could be rescued by treatment with an miR-127-3p inhibitor. Conclusion Our data indicates, for the first time, an essential role for the circSDHC/miR-127-3p/CDKN3/E2F1 axis in RCC progression. Thus, circSDHC has potential to be a new therapeutic target in patients with RCC.

scholarly journals TMOD-15. EFFICACY OF THE MDM2 INHIBITOR KRT-232 IN GLIOBLASTOMA PATIENT-DERIVED XENOGRAFT MODELS

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii231-ii231
Author(s):  
Rachael Vaubel ◽  
Ann Mladek ◽  
Yu Zhao ◽  
Shiv K Gupta ◽  
Minjee Kim ◽  
...  
Keyword(s):  
Target Genes ◽  
Xenograft Model ◽  
Culture Conditions ◽  
Patient Derived Xenograft ◽  
Fold Induction ◽  
Extended Survival ◽  
Mdm2 Amplification ◽  
Mdm2 Inhibitor

Abstract Non-genotoxic reactivation of p53 by MDM2 inhibitors represents a promising therapeutic strategy for tumors with wild-type TP53, particularly tumors harboring MDM2 amplification. MDM2 controls p53 levels by targeting it for degradation, while disruption of the MDM2-p53 interaction causes rapid accumulation of p53 and activation of the p53 pathway. We examined the efficacy of the small molecule MDM2 inhibitor KRT-232, alone and in combination with radiation therapy (RT), in MDM2-amplified and/or p53 wildtype patient-derived xenograft (PDX) models of glioblastoma in vitro and in vivo. In vitro, glioblastoma PDX explant cultures showed sensitivity to KRT-232, both tumors with MDM2 amplification (GBM108 and G148) and non-amplified but TP53-wildtype lines (GBM10, GBM14, and GBM39), with IC50s ranging from 300-800 nM in FBS culture conditions. A TP53 p.F270C mutant PDX (GBM43) was inherently resistant, with IC50 >3000 nM. In the MDM2-amplified GBM108 line, KRT-232 led to a robust (5-6 fold) induction of p53-target genes p21, PUMA, and NOXA, with initiation of both apoptosis and senescence. Expression of p21 and PUMA was greater with KRT-232 in combination with RT (25-35 fold induction), while stable knock-down of p53 in GBM108 led to complete resistance to KRT-232. In contrast, GBM10 showed lower induction of p21 and PUMA (2-3 fold) and was more resistant to KRT-232. In an orthotopic GBM108 xenograft model, treatment with KRT-232 +/- RT for one week extended survival from 22 days (placebo) to 46 days (KRT-232 alone); combination KRT-232 + RT further extended survival (77 days) over RT alone (31 days). KRT-232 is an effective treatment in a subset of glioblastoma pre-clinical models alone and in combination with RT. Further studies are underway to understand the mechanisms conferring innate sensitivity or resistance to KRT-232.

scholarly journals Ways into Understanding HIF Inhibition

Cancers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 159
Author(s):  
Tina Schönberger ◽  
Joachim Fandrey ◽  
Katrin Prost-Fingerle
Keyword(s):  
Protein Interactions ◽  
Target Genes ◽  
Protein Protein Interactions ◽  
Low Oxygen ◽  
Drug Candidates ◽  
Open Questions ◽  
Wide Range ◽  
Hif Pathway

Hypoxia is a key characteristic of tumor tissue. Cancer cells adapt to low oxygen by activating hypoxia-inducible factors (HIFs), ensuring their survival and continued growth despite this hostile environment. Therefore, the inhibition of HIFs and their target genes is a promising and emerging field of cancer research. Several drug candidates target protein–protein interactions or transcription mechanisms of the HIF pathway in order to interfere with activation of this pathway, which is deregulated in a wide range of solid and liquid cancers. Although some inhibitors are already in clinical trials, open questions remain with respect to their modes of action. New imaging technologies using luminescent and fluorescent methods or nanobodies to complement widely used approaches such as chromatin immunoprecipitation may help to answer some of these questions. In this review, we aim to summarize current inhibitor classes targeting the HIF pathway and to provide an overview of in vitro and in vivo techniques that could improve the understanding of inhibitor mechanisms. Unravelling the distinct principles regarding how inhibitors work is an indispensable step for efficient clinical applications and safety of anticancer compounds.

scholarly journals Akt kinase LANCL2 functions as a key driver in EGFR-mutant lung adenocarcinoma tumorigenesis

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Yuqing Lou ◽  
Jianlin Xu ◽  
Yanwei Zhang ◽  
Wei Zhang ◽  
Xueyan Zhang ◽  
...  
Keyword(s):  
Lung Adenocarcinoma ◽  
Cell Line ◽  
Quantitative Polymerase Chain Reaction ◽  
Mutant Cell ◽  
A549 Cells ◽  
The Cancer Genome Atlas ◽  
Akt Kinase ◽  
Egfr Expression

AbstractEpidermal growth factor receptor (EGFR) is a key oncogene in lung adenocarcinoma (LUAD). Resistance to EGFR tyrosine kinase inhibitors is a major obstacle for EGFR-mutant LUAD patients. Our gene chip array, quantitative polymerase chain reaction validation, and shRNA-based high-content screening identified the Akt kinase lanthionine synthetase C-like protein 2 (LANCL2) as a pro-proliferative gene in the EGFR-mutant LUAD cell line PC9. Therefore, we investigated whether LANCL2 plays a role in promoting cell proliferation and drug resistance in EGFR-mutant LUAD. In silico clinical correlation analysis using the Cancer Genome Atlas Lung Adenocarcinoma dataset revealed a positive correlation between LANCL2 and EGFR expression and an inverse relationship between LANCL2 gain-of-function and survival in LUAD patients. The EGFR-mutant LUAD cell lines PC9 and HCC827 displayed higher LANCL2 expression than the non-EGFR-mutant cell line A549. In addition, LANCL2 was downregulated following gefitinib+pemetrexed combination therapy in PC9 cells. LANCL2 knockdown reduced proliferation and enhanced apoptosis in PC9, HCC827, and A549 cells in vitro and suppressed murine PC9 xenograft tumor growth in vivo. Notably, LANCL2 overexpression rescued these effects and promoted gefitinib + pemetrexed resistance in PC9 and HCC827 cells. Pathway analysis and co-immunoprecipitation followed by mass spectrometry of differentially-expressed genes in LANCL2 knockdown cells revealed enrichment of several cancer signaling pathways. In addition, Filamin A and glutathione S-transferase Mu 3 were identified as two novel protein interactors of LANCL2. In conclusion, LANCL2 promotes tumorigenic proliferation, suppresses apoptosis, and promotes gefitinib+pemetrexed resistance in EGFR-mutant LUAD cells. Based on the positive association between LANCL2, EGFR, and downstream Akt signaling, LANCL2 may be a promising new therapeutic target for EGFR-mutant LUAD.

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