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 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 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 FGIN-1-27 Inhibits Melanogenesis by Regulating Protein Kinase A/cAMP-Responsive Element-Binding, Protein Kinase C-β, and Mitogen-Activated Protein Kinase Pathways

2020 ◽  
Vol 11 ◽  
Author(s):  
Jinpeng Lv ◽  
Songzhou Jiang ◽  
Ying Yang ◽  
Ximei Zhang ◽  
Rongyin Gao ◽  
...  
Keyword(s):  
Protein Kinase ◽  
The Body ◽  
Tyrosinase Activity ◽  
Mitogen Activated Protein Kinase ◽  
Mushroom Tyrosinase ◽  
Mitogen Activated Protein ◽  
Element Binding Protein ◽  
Responsive Element

FGIN-1-27 is a synthetic mitochondrial diazepam binding inhibitor receptor (MDR) agonist that has demonstrated pro-apoptotic, anti-anxiety, and steroidogenic activity in various studies. Here we report, for the first time, the anti-melanogenic efficacy of FGIN-1-27 in vitro and in vivo. FGIN-1-27 significantly inhibited basal and α-melanocyte-stimulating hormone (α-MSH)-, 1-Oleoyl-2-acetyl-sn-glycerol (OAG)- and Endothelin-1 (ET-1)-induced melanogenesis without cellular toxicity. Mushroom tyrosinase activity assay showed that FGIN-1-27 did not directly inhibit tyrosinase activity, which suggested that FGIN-1-27 was not a direct inhibitor of tyrosinase. Although it was not capable of modulating the catalytic activity of mushroom tyrosinase in vitro, FGIN-1-27 downregulated the expression levels of key proteins that function in melanogenesis. FGIN-1-27 played these functions mainly by suppressing the PKA/CREB, PKC-β, and MAPK pathways. Once inactivated, it decreased the expression of MITF, tyrosinase, TRP-1, TRP-2, and inhibited the tyrosinase activity, finally inhibiting melanogenesis. During in vivo experiments, FGIN-1-27 inhibited the body pigmentation of zebrafish and reduced UVB-induced hyperpigmentation in guinea pig skin, but not a reduction of numbers of melanocytes. Our findings indicated that FGIN-1-27 exhibited no cytotoxicity and inhibited melanogenesis in both in vitro and in vivo models. It may prove quite useful as a safer skin-whitening agent.

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 miR-205 Inhibits Neuroblastoma Growth by Targeting cAMP-Responsive Element-Binding Protein 1

2018 ◽  
Vol 26 (3) ◽  
pp. 445-455 ◽  
Author(s):  
Shu Chen ◽  
Lianhua Jin ◽  
Shu Nie ◽  
Lizhi Han ◽  
Na Lu ◽  
...  
Keyword(s):  
Binding Protein ◽  
Staging System ◽  
Migration And Invasion ◽  
Tissue Samples ◽  
Direct Target Gene ◽  
Element Binding Protein ◽  
Responsive Element ◽  
Camp Responsive Element Binding

Accumulating evidence indicates that microRNA-205 (miR-205) is involved in tumor initiation, development, and metastasis in various cancers. However, its functions in neuroblastoma (NB) remain largely unclear. Here we found that miR-205 was significantly downregulated in human NB tissue samples and cell lines. miR-205 expression was lower in poorly differentiated NB tissues and those of advanced International Neuroblastoma Staging System stage. In addition, restoration of miR-205 in NB cells suppressed proliferation, migration, and invasion and induced cell apoptosis in vitro, as well as impaired tumor growth in vivo. cAMP-responsive element-binding protein 1 (CREB1) was identified as a direct target gene of miR-205. Expression of an miR-205 mimic in NB cells significantly diminished expression of CREB1 and the CREB1 targets BCL-2 and MMP9. CREB1 was also found to be upregulated in human NB tissues, its expression being inversely correlated with miR-205 expression (r = −0.554, p = 0.003). Importantly, CREB1 upregulation partially rescued the inhibitory effects of miR-205 on NB cells. These findings suggest that miR-205 may function as a tumor suppressor in NB by targeting CREB1.

scholarly journals CaM kinase II regulates cardiac hemoglobin expression through histone phosphorylation upon sympathetic activation

2019 ◽  
Vol 116 (44) ◽  
pp. 22282-22287
Author(s):  
Ali Reza Saadatmand ◽  
Viviana Sramek ◽  
Silvio Weber ◽  
Daniel Finke ◽  
Matthias Dewenter ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Target Genes ◽  
Ventricular Myocardium ◽  
Cam Kinase Ii ◽  
Sympathetic Activation ◽  
Cam Kinase ◽  
In Vivo Experiments ◽  
Underlying Mechanisms

Sympathetic activation of β-adrenoreceptors (β-AR) represents a hallmark in the development of heart failure (HF). However, little is known about the underlying mechanisms of gene regulation. In human ventricular myocardium from patients with end-stage HF, we found high levels of phosphorylated histone 3 at serine-28 (H3S28p). H3S28p was increased by inhibition of the catecholamine-sensitive protein phosphatase 1 and decreased by β-blocker pretreatment. By a series of in vitro and in vivo experiments, we show that the β-AR downstream protein kinase CaM kinase II (CaMKII) directly binds and phosphorylates H3S28. Whereas, in CaMKII-deficient myocytes, acute catecholaminergic stimulation resulted in some degree of H3S28p, sustained catecholaminergic stimulation almost entirely failed to induce H3S28p. Genome-wide analysis of CaMKII-mediated H3S28p in response to chronic β-AR stress by chromatin immunoprecipitation followed by massive genomic sequencing led to the identification of CaMKII-dependent H3S28p target genes. Forty percent of differentially H3S28p-enriched genomic regions were associated with differential, mostly increased expression of the nearest genes, pointing to CaMKII-dependent H3S28p as an activating histone mark. Remarkably, the adult hemoglobin genes showed an H3S28p enrichment close to their transcriptional start or end sites, which was associated with increased messenger RNA and protein expression. In summary, we demonstrate that chronic β-AR activation leads to CaMKII-mediated H3S28p in cardiomyocytes. Thus, H3S28p-dependent changes may play an unexpected role for cardiac hemoglobin regulation in the context of sympathetic activation. These data also imply that CaMKII may be a yet unrecognized stress-responsive regulator of hematopoesis.

scholarly journals CREB is a critical regulator of normal hematopoiesis and leukemogenesis

Blood ◽  
2008 ◽  
Vol 111 (3) ◽  
pp. 1182-1192 ◽  
Author(s):  
Jerry C. Cheng ◽  
Kentaro Kinjo ◽  
Dejah R. Judelson ◽  
Jenny Chang ◽  
Winston S. Wu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Myeloid Leukemia ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Myeloproliferative Disease ◽  
Hematopoietic Stem ◽  
Element Binding Protein ◽  
Responsive Element

AbstractThe cAMP-responsive element binding protein (CREB) is a 43-kDa nuclear transcription factor that regulates cell growth, memory, and glucose homeostasis. We showed previously that CREB is amplified in myeloid leukemia blasts and expressed at higher levels in leukemia stem cells from patients with myeloid leukemia. CREB transgenic mice develop myeloproliferative disease after 1 year, but not leukemia, suggesting that CREB contributes to but is not sufficient for leukemogenesis. Here, we show that CREB is most highly expressed in lineage negative hematopoietic stem cells (HSCs). To understand the role of CREB in hematopoietic progenitors and leukemia cells, we examined the effects of RNA interference (RNAi) to knock down CREB expression in vitro and in vivo. Transduction of primary HSCs or myeloid leukemia cells with lentiviral CREB shRNAs resulted in decreased proliferation of stem cells, cell- cycle abnormalities, and inhibition of CREB transcription. Mice that received transplants of bone marrow transduced with CREB shRNA had decreased committed progenitors compared with control mice. Mice injected with Ba/F3 cells expressing either Bcr-Abl wild-type or T315I mutation with CREB shRNA had delayed leukemic infiltration by bioluminescence imaging and prolonged median survival. Our results suggest that CREB is critical for normal myelopoiesis and leukemia cell proliferation.

Switching the in vivo specificity of a minimal Hox-responsive element

Development ◽  
1997 ◽  
Vol 124 (10) ◽  
pp. 2007-2014 ◽  
Author(s):  
S.K. Chan ◽  
H.D. Ryoo ◽  
A. Gould ◽  
R. Krumlauf ◽  
R.S. Mann
Keyword(s):  
Binding Sites ◽  
Target Genes ◽  
Expression Patterns ◽  
High Specificity ◽  
Mouse Embryos ◽  
Homeodomain Protein ◽  
Homeodomain Proteins ◽  
Responsive Element

The homeodomain proteins encoded by the Hox complex genes do not bind DNA with high specificity. In vitro, Hox specificity can be increased by binding to DNA cooperatively with the homeodomain protein extradenticle or its vertebrate homologs, the pbx proteins (together, the PBC family). Here we show that a two basepair change in a Hox-PBC binding site switches the Hox-dependent expression pattern generated in vivo, from labial to Deformed. The change in vivo correlates with an altered Hox binding specificity in vitro. Further, we identify similar Deformed-PBC binding sites in the Deformed and Hoxb-4 genes and show that they generate Deformed or Hoxb-4 expression patterns in Drosophila and mouse embryos, respectively. These results suggest a model in which Hox-PBC binding sites play an instructive role in Hox specificity by promoting the formation of different Hox-PBC heterodimers in vivo. Thus, the choice of Hox partner, and therefore Hox target genes, depends on subtle differences between Hox-PBC binding sites.

scholarly journals LncRNA DLX6-AS1 regulates osteosarcoma progression via the miR-200a-3p/GPM6P axis

STEMedicine ◽  
2022 ◽  
Vol 3 (1) ◽  
pp. e111
Author(s):  
Tianyi Wu ◽  
Chen Huang ◽  
Feng Wang
Keyword(s):  
Target Genes ◽  
Critical Role ◽  
Tumor Xenograft ◽  
In Vivo Experiments ◽  
Biochemical Assays ◽  
Cell Metastasis ◽  
Underlying Mechanisms ◽  
Si Rna

LncRNA DLX6-AS1 takes part in the progression of various cancers. However, it is not elaborated clearly in osteosarcoma (OS) development. Therefore, we aimed to explore the impacts and specific mechanisms of DLX6-AS1 on the progression of OS. We estimated the pattern of DLX6-AS1 expression in Ost tissues and cells via quantitative reverse transcription polymerase chain reaction. A number of biochemical assays were carried out to assess the effects of DLX6-AS1. Target genes were predicted by bioinformatics methods. Then we used the transfection of si-RNA, miRNA inhibitor, and miRNA mimics to explore the underlying mechanisms and built tumor xenograft models for the in vivo experiments. A higher expression of DLX6-AS1 was found in OS tissues and cell lines, while knockdown of DXL6-AS1 suppressed OS cell metastasis and proliferation in vitro and in vivo. Mechanistically, it was revealed that DXL6-AS1 sponged miR-200a-3p, thus positively regulating the downstream GPM6B. In summary, DLX6-AS1 knockdown would inhibit OS cell migration, cell invasion, and cell proliferation, in which the DXL6-AS1/ miR-200a-3p/ GPM6B axis played a critical role.

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.

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