Molecular characteristics and induction profiles of hypoxia-inducible factor-1αand other basic helix–loop–helix and Per–Arnt–Sim domain-containing proteins identified in a carcinogenic liver flukeClonorchis sinensis

Parasitology ◽  
2018 ◽  
Vol 146 (2) ◽  
pp. 176-186
Author(s):  
Seon-Hee Kim ◽  
Gyu-Seok Oh ◽  
Woon-Mok Sohn ◽  
Kihyun Lee ◽  
Hyun-Jong Yang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Clonorchis Sinensis ◽  
Hypoxia Inducible Factor ◽  
Hypoxic Condition ◽  
Molecular Structures ◽  
Molecular Characteristics ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Aryl Hydrocarbon ◽  
Oxygen Condition

AbstractClonorchis sinensis(C. sinensis), a trematode parasite that invades the hypoxic hepatobiliary tract of vertebrate hosts requires a considerable amount of oxygen for its sexual reproduction and energy metabolism. However, little is known regarding the molecular mechanism ofC. sinensisinvolved in the adaptation to the hypoxic environments. In this study, we investigated the molecular structures and induction patterns of hypoxia-inducible factor-1α(HIF-1α) and other basic helix–loop–helix and Per–Arnt–Sim (bHLH–PAS) domain-containing proteins such as HIF-1β, single-minded protein and aryl hydrocarbon receptor, which might prompt adaptive response to hypoxia, inC. sinensis. These proteins possessed various bHLH–PAS family-specific domains. Expression ofC. sinensis HIF-1α(CsHIF-1α) was highly induced in worms which were either exposed to a hypoxic condition or co-incubated with human cholangiocytes. In addition to oxygen, nitric oxide and nitrite affected theCsHIF-1αexpression depending on the surrounding oxygen concentration. Treatment using a prolyl hydroxylase-domain protein inhibitor under 20%-oxygen condition resulted in an increase in the CsHIF-1αlevel. Conversely, the otherbHLH–PASgenes were less responsive to these exogenous stimuli. We suggest that nitrite and nitric oxide, as well as oxygen, coordinately involve in the regulation of HIF-1αexpression to adapt to the hypoxic host environments inC. sinensis.

scholarly journals Sequence Analysis and Phylogenetic Studies of Hypoxia-Inducible Factor-1α

2017 ◽  
Vol 16 ◽  
pp. 117693511771224
Author(s):  
Jagadeesha Poyya ◽  
Chandrashekhar G Joshi ◽  
D Jagadeesha Kumar ◽  
HG Nagendra
Keyword(s):  
Hypoxia Inducible Factor ◽  
Hypoxic Condition ◽  
Metabolic Reprogramming ◽  
Low Oxygen ◽  
Hypoxia Inducible Factor 1Α ◽  
Helix Loop Helix ◽  
Phylogenetic Studies ◽  
Sequence Variations ◽  
Potential Risk Factors ◽  
Inhibitory Domain

Hypoxia-inducible factors (HIF) belong to the basic helix loop helix–PER ARNT SIM (bHLH-PAS) family of transcription factors that induce metabolic reprogramming under hypoxic condition. The phylogenetic studies of hypoxia-inducible factor-1α (HIF-1α) sequences across different organisms/species may leave a clue on the evolutionary relationships and its probable correlation to tumorigenesis and adaptation to low oxygen environments. In this study, we have aimed at the evolutionary investigation of the protein HIF-1α across different species to decipher their sequence variations/mutations and look into the probable causes and abnormal behaviour of this molecule under exotic conditions. In total, 16 homologous sequences for HIF-1α were retrieved from the National Center for Biotechnology Information. Sequence identity was performed using the Needle program. Multiple aligned sequences were used to construct the phylogeny using the neighbour-joining method. Most of the changes were observed in oxygen-dependent degradation domain and inhibitory domain. Sixteen sequences were clustered into 5 groups. The phylogenetic analysis clearly highlighted the variations that were observed at the sequence level. Comparisons of the HIF-1α sequence among cancer-prone and cancer-resistant animals enable us to find out the probable clues towards potential risk factors in the development of cancer.

scholarly journals cDNA cloning and tissue-specific expression of a novel basic helix-loop-helix/PAS factor (Arnt2) with close sequence similarity to the aryl hydrocarbon receptor nuclear translocator (Arnt).

1996 ◽  
Vol 16 (4) ◽  
pp. 1706-1713 ◽  
Author(s):  
K Hirose ◽  
M Morita ◽  
M Ema ◽  
J Mimura ◽  
H Hamada ◽  
...  
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Sequence Similarity ◽  
Cdna Clones ◽  
Mobility Shift ◽  
Phylogenetic Groups ◽  
Specific Expression ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Aryl Hydrocarbon ◽  
Adult Mice

We isolated mouse cDNA clones (Arnt2) that are highly similar to but distinct from the aryl hydrocarbon receptor (AhR) nuclear translocator (Arnt). The composite cDNA covered a 2,443-bp sequence consisting of a putative 2,136-bp open reading frame encoding a polypeptide of 712 amino acids. The predicted Arnt2 polypeptide carries a characteristic basic helix-loop-helix (bHLH)/PAS motif in its N-terminal region with close similarity (81% identity) to that of mouse Arnt and has an overall sequence identity of 57% with Arnt. Biochemical properties and interaction of Arnt2 with other bHLH/PAS proteins were investigated by coimmunoprecipitation assays, gel mobility shift assays, and the yeast two-hybrid system. Arnt2 interacted with AhR and mouse Sim as efficiently as Arnt, and the Arnt2-AhR complex recognized and bound specifically the xenobiotic responsive element (XRE) sequence. Expression of Arnt2 successfully rescued XRE-driven reporter gene activity in the Arnt-defective c4 mutant of Hepa-1 cells. RNA blot analysis revealed that expression of Arnt2 mRNA was restricted to the brains and kidneys of adult mice, while Arnt mRNA was expressed ubiquitously. In addition, whole-mount in situ hybridization of 9.5-day mouse embryos showed that Arnt2 mRNA was expressed in the dorsal neural tube and branchial arch 1, while Arnt transcripts were detected broadly in various tissues of mesodermal and endodermal origins. These results suggest that Arnt2 may play different roles from Arnt both in adult mice and in developing embryos. Finally, sequence comparison of the currently known bHLH/PAS proteins indicates a division into two phylogenetic groups: the Arnt group, containing Arnt, Arnt2, and Per, and the AhR group, consisting of AhR, Sim, and Hif-1alpha.

scholarly journals The murine Sim-2 gene product inhibits transcription by active repression and functional interference.

1997 ◽  
Vol 17 (9) ◽  
pp. 4933-4947 ◽  
Author(s):  
P Moffett ◽  
M Reece ◽  
J Pelletier
Keyword(s):  
Gene Product ◽  
Cell Fate ◽  
Transcriptional Activation ◽  
Mammalian Cells ◽  
Regulatory Protein ◽  
Hypoxia Inducible Factor ◽  
Structure Mapping ◽  
Helix Loop Helix ◽  
Aryl Hydrocarbon ◽  
Transcription Complexes

The Drosophila single-minded (Dsim) gene encodes a master regulatory protein involved in cell fate determination during midline development. This protein is a member of a rapidly expanding family of gene products possessing basic helix-loop-helix (bHLH) and hydrophobic PAS (designated a conserved region among PER, ARNT [aryl hydrocarbon receptor nuclear translocator] and SIM) protein association domains. Members of this family function as central transcriptional regulators in cellular differentiation and in the response to environmental stimuli such as xenobiotics and hypoxia. We have previously identified a murine member of this family, called mSim-2, showing sequence homology to the bHLH and PAS domains of Dsim. Immunoprecipitation experiments with recombinant proteins indicate that mSIM-2 associates with the arnt gene product. In the present work, by using fine-structure mapping we found that the HLH and PAS motifs of both proteins are required for optimal association. Forced expression of GAL4/mSIM-2 fusion constructs in mammalian cells demonstrated the presence of two separable repression domains within the carboxy terminus of mSIM-2. We found that mSIM-2 is capable of repressing ARNT-mediated transcriptional activation in a mammalian two-hybrid system. This effect (i) is dependent on the ability of mSIM-2 and ARNT to heterodimerize, (ii) is dependent on the presence of the mSIM-2 carboxy-terminal repression domain, and (iii) is not specific to the ARNT activation domain. These results suggest that mSIM-2 repression activity can dominantly override the activation potential of adjacent transcription factors. We also demonstrated that mSIM-2 can functionally interfere with hypoxia-inducible factor 1alpha (HIF-1alpha)/ARNT transcription complexes, providing a second mechanism by which mSIM-2 may inhibit transcription.

scholarly journals Induction of Endothelial PAS Domain Protein-1 by Hypoxia: Characterization and Comparison With Hypoxia-Inducible Factor-1α

Blood ◽  
1998 ◽  
Vol 92 (7) ◽  
pp. 2260-2268 ◽  
Author(s):  
M.S. Wiesener ◽  
H. Turley ◽  
W.E. Allen ◽  
C. Willam ◽  
K.-U. Eckardt ◽  
...  
Keyword(s):  
Mutant Cell ◽  
Hypoxia Inducible Factor ◽  
Cell Types ◽  
Pas Domain ◽  
Functional Studies ◽  
Hypoxia Inducible Factor 1 ◽  
Helix Loop Helix ◽  
Aryl Hydrocarbon ◽  
Domain Protein ◽  
Different Cell Types

Abstract Hypoxia results in adaptive changes in the transcription of a range of genes including erythropoietin. An important mediator is hypoxia-inducible factor-1 (HIF-1), a DNA binding complex shown to contain at least two basic helix-loop-helix PAS-domain (bHLH-PAS) proteins, HIF-1α and aryl hydrocarbon nuclear receptor translocator (ARNT). In response to hypoxia, HIF-1α is activated and accumulates rapidly in the cell. Endothelial PAS domain protein 1 (EPAS-1) is a recently identified bHLH-PAS protein with 48% identity to HIF-1α, raising the question of its role in responses to hypoxia. We developed specific antibodies and studied expression and regulation of EPAS-1 mRNA and protein across a range of human cell lines. EPAS-1 was widely expressed, and strongly induced by hypoxia at the level of protein but not mRNA. Comparison of the effect of a range of activating and inhibitory stimuli showed striking similarities in the EPAS-1 and HIF-1α responses. Although major differences were observed in the abundance of EPAS-1 and HIF-1α in different cell types, differences in the inducible response were subtle with EPAS-1 protein being slightly more evident in normoxic and mildly hypoxic cells. Functional studies in a mutant cell line (Ka13) expressing neither HIF-1α nor EPAS-1 confirmed that both proteins interact with hypoxically responsive targets, but suggest target specificity with greater EPAS-1 transactivation (relative to HIF-1α transactivation) of the VEGF promoter than the LDH-A promoter.

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