scholarly journals Dietary Monoterpenoids As a New Class of Allosteric Human Aryl Hydrocarbon Receptor Antagonists

2020 ◽  
Author(s):  
Karolína Poulíková ◽  
Iveta Zůvalová ◽  
Barbora Vyhlídalová ◽  
Kristýna Krasulová ◽  
Eva Jiskrová ◽  
...  

ABSTRACTCarvones, the constituents of essential oils of dill, caraway, and spearmint, were reported to antagonize the human aryl hydrocarbon receptor (AhR); however, the exact molecular mechanism remains elusive. We show that carvones are non-competitive allosteric antagonists of the AhR that inhibit the induction of AhR target genes in a ligand-selective and cell type-specific manner. Carvones do not displace radiolabeled ligand from binding at the AhR, but they bind allosterically within the bHLH/PAS-A region of the AhR. Carvones did not influence a translocation of ligand-activated AhR into the nucleus. Carvones inhibited the heterodimerization of the AhR with its canonical partner ARNT and subsequent binding of the AhR to the promotor of CYP1A1. Interaction of carvones with potential off-targets, including ARNT and protein kinases, was refuted. This is the first report of a small dietary monoterpenoids as a new class of AhR non-competitive allosteric antagonists with the potential preventive and therapeutic application.

Author(s):  
Brittany Cain ◽  
Brian Gebelein

Metazoans differentially express multiple Hox transcription factors to specify diverse cell fates along the developing anterior-posterior axis. Two challenges arise when trying to understand how the Hox transcription factors regulate the required target genes for morphogenesis: First, how does each Hox factor differ from one another to accurately activate and repress target genes required for the formation of distinct segment and regional identities? Second, how can a Hox factor that is broadly expressed in many tissues within a segment impact the development of specific organs by regulating target genes in a cell type-specific manner? In this review, we highlight how recent genomic, interactome, and cis-regulatory studies are providing new insights into answering these two questions. Collectively, these studies suggest that Hox factors may differentially modify the chromatin of gene targets as well as utilize numerous interactions with additional co-activators, co-repressors, and sequence-specific transcription factors to achieve accurate segment and cell type-specific transcriptional outcomes.


2019 ◽  
Author(s):  
Xin Wang ◽  
Lingling Ye ◽  
Robertas Ursache ◽  
Ari Pekka Mähönen

ABSTRACTConditional manipulation of gene expression is a key approach to investigating the primary function of a gene in a biological process. While conditional and cell-type specific overexpression systems exist for plants, there are currently no systems available to disable a gene completely and conditionally. Here, we present a novel tool with which target genes can be efficiently conditionally knocked out at any developmental stage. The target gene is manipulated using the CRISPR-Cas9 genome editing technology, and conditionality is achieved with the well-established estrogen-inducible XVE system. Target genes can also be knocked-out in a cell-type specific manner. Our tool is easy to construct and will be particularly useful for studying genes which have null-alleles that are non-viable or show strong developmental defects.


2000 ◽  
Vol 191 (8) ◽  
pp. 1281-1292 ◽  
Author(s):  
Raelene J. Grumont ◽  
Steve Gerondakis

In lymphocytes, the Rel transcription factor is essential in establishing a pattern of gene expression that promotes cell proliferation, survival, and differentiation. Here we show that mitogen-induced expression of interferon (IFN) regulatory factor 4 (IRF-4), a lymphoid-specific member of the IFN family of transcription factors, is Rel dependent. Consistent with IRF-4 functioning as a repressor of IFN-induced gene expression, the absence of IRF-4 expression in c-rel−/− B cells coincided with a greater sensitivity of these cells to the antiproliferative activity of IFNs. In turn, enforced expression of an IRF-4 transgene restored IFN modulated c-rel−/− B cell proliferation to that of wild-type cells. This cross-regulation between two different signaling pathways represents a novel mechanism that Rel/nuclear factor κB can repress the transcription of IFN-regulated genes in a cell type–specific manner.


2018 ◽  
Vol 19 (12) ◽  
pp. 3762 ◽  
Author(s):  
Anaïs Wakx ◽  
Margaux Nedder ◽  
Céline Tomkiewicz-Raulet ◽  
Jessica Dalmasso ◽  
Audrey Chissey ◽  
...  

The human placenta is an organ between the blood of the mother and the fetus, which is essential for fetal development. It also plays a role as a selective barrier against environmental pollutants that may bypass epithelial barriers and reach the placenta, with implications for the outcome of pregnancy. The aryl hydrocarbon receptor (AhR) is one of the most important environmental-sensor transcription factors and mediates the metabolism of a wide variety of xenobiotics. Nevertheless, the identification of dietary and endogenous ligands of AhR suggest that it may also fulfil physiological functions with which pollutants may interfere. Placental AhR expression and activity is largely unknown. We established the cartography of AhR expression at transcript and protein levels, its cellular distribution, and its transcriptional activity toward the expression of its main target genes. We studied the profile of AhR expression and activity during different pregnancy periods, during trophoblasts differentiation in vitro, and in a trophoblast cell line. Using diverse methods, such as cell fractionation and immunofluorescence microscopy, we found a constitutive nuclear localization of AhR in every placental model, in the absence of any voluntarily-added exogenous activator. Our data suggest an intrinsic activation of AhR due to the presence of endogenous placental ligands.


Author(s):  
Jieru Li ◽  
Alexandros Pertsinidis

Establishing cell-type-specific gene expression programs relies on the action of distal enhancers, cis-regulatory elements that can activate target genes over large genomic distances — up to Mega-bases away. How distal enhancers physically relay regulatory information to target promoters has remained a mystery. Here, we review the latest developments and insights into promoter–enhancer communication mechanisms revealed by live-cell, real-time single-molecule imaging approaches.


2020 ◽  
Vol 62 (1) ◽  
pp. 99-106 ◽  
Author(s):  
Yuriko Goto ◽  
Miho Ibi ◽  
Hirotaka Sato ◽  
Junichi Tanaka ◽  
Rika Yasuhara ◽  
...  

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