scholarly journals Evolution of ventricular myocyte electrophysiology

2008 ◽  
Vol 35 (3) ◽  
pp. 262-272 ◽  
Author(s):  
Barbara Rosati ◽  
Min Dong ◽  
Lan Cheng ◽  
Shian-Ren Liou ◽  
Qinghong Yan ◽  
...  
Keyword(s):  
Action Potential ◽  
Functional Properties ◽  
Small Mammals ◽  
Action Potential Duration ◽  
Structural Evolution ◽  
Regulatory Elements ◽  
Proximal Promoter ◽  
Regulatory Evolution ◽  
Promoter Regions ◽  
Primary Determinant

The relative importance of regulatory versus structural evolution for the evolution of different biological systems is a subject of controversy. The primacy of regulatory evolution in the diversification of morphological traits has been promoted by many evolutionary developmental biologists. For physiological traits, however, the role of regulatory evolution has received less attention or has been considered to be relatively unimportant. To address this issue for electrophysiological systems, we examined the importance of regulatory and structural evolution in the evolution of the electrophysiological function of cardiac myocytes in mammals. In particular, two related phenomena were studied: the change in action potential morphology in small mammals and the scaling of action potential duration across mammalian phylogeny. In general, the functional properties of the ion channels involved in ventricular action potential repolarization were found to be relatively invariant. In contrast, there were large changes in the expression levels of multiple ion channel and transporter genes. For the Kv2.1 and Kv4.2 potassium channel genes, which are primary determinants of the action potential morphology in small mammals, the functional properties of the proximal promoter regions were found to vary in concordance with species-dependent differences in mRNA expression, suggesting that evolution of cis-regulatory elements is the primary determinant of this trait. Scaling of action potential duration was found to be a complex phenomenon, involving changes in the expression of a large number of channels and transporters. In this case, it is concluded that regulatory evolution is the predominant mechanism by which the scaling is achieved.

scholarly journals Characterization and Activity Analyses of the FLOWERING LOCUS T Promoter in Gossypium Hirsutum

2019 ◽  
Vol 20 (19) ◽  
pp. 4769 ◽  
Author(s):  
Na Sang ◽  
Darun Cai ◽  
Chao Li ◽  
Yuqiang Sun ◽  
Xianzhong Huang
Keyword(s):  
Gossypium Hirsutum ◽  
Regulatory Elements ◽  
Proximal Promoter ◽  
Activity Levels ◽  
Loss Of Function ◽  
Flowering Locus T ◽  
Promoter Regions ◽  
Core Motif ◽  
Late Flowering ◽  
Flowering Locus

Flowering transition is a crucial development process in cotton (Gossypium hirsutum L.), and the flowering time is closely correlated with the timing of FLOWERING LOCUS T (FT) expression. However, the mechanism underlying the coordination of various cis-regulatory elements in the FT promoter of cotton has not been determined. In this study, a 5.9-kb promoter of FT was identified from cotton. A bioinformatics analysis showed that multiple insertion–deletion sites existed in the 5.9-kb promoter. Different expression levels of a reporter gene, and the induction by sequential deletions in GhFT promoter, demonstrated that 1.8-kb of the GhFT promoter was stronger than 4.2-, 4.8-, and 5.9-kb promoter fragments. The binding sites of the CONSTANS (CO) and NUCLEAR FACTOR Y transcription factors were located within the 1.0-kb sequence upstream of the FT transcription start site. A large number of repeat segments were identified in proximal promoter regions (−1.1 to −1.4 kb). A complementation analysis of deletion constructs between 1.0 and 1.8 kb of G. hirsutum, Gossypium arboretum, and Gossypium raimondii FT promoters revealed that the 1.0-kb fragment significantly rescued the late-flowering phenotype of the Arabidopsis FT loss-of-function mutant ft-10, whereas the 1.8-kb promoter only slightly rescued the late-flowering phenotype. Furthermore, the conserved CORE motif in the cotton FT promoter is an atypical TGTG(N2-3)ATG, but the number of arbitrary bases between TGTG and ATG is uncertain. Thus, the proximal FT promoter region might play an important role affecting the activity levels of FT promoters in cotton flowering.

scholarly journals Deciphering Transcriptional Regulation of Human Core Promoters

2017 ◽  
Author(s):  
Shira Weingarten-Gabbay ◽  
Ronit Nir ◽  
Shai Lubliner ◽  
Eilon Sharon ◽  
Yael Kalma ◽  
...  
Keyword(s):  
Binding Site ◽  
Human Genome ◽  
Core Promoter ◽  
Regulatory Elements ◽  
Proximal Promoter ◽  
Promoter Regions ◽  
Core Promoters ◽  
Optimal Distance ◽  
Negative Effect ◽  
Positive Effect

ABSTRACTDespite its pivotal role in regulating transcription, our understanding of core promoter function, architecture, and cis-regulatory elements is lacking. Here, we devised a highthroughput assay to quantify the activity of ∼15,000 fully designed core promoters that we integrated and expressed from a fixed location within the human genome. We find that core promoters drive transcription unidirectionally, and that sequences originating from promoters exhibit stronger activity than sequences originating from enhancers. Testing multiple combinations and distances of core promoter elements, we observe a positive effect of TATA and Initiator, a negative effect of BREu and BREd, and a 10bp periodicity in the optimal distance between the TATA and the Initiator. By comprehensively screening TF binding-sites, we show that site orientation has little effect, that the effect of binding site number on expression is factor-specific, and that there is a striking agreement between the effect of binding site multiplicity in our assay and the tendency of the TF to appear in homotypic clusters throughout the genome. Overall, our results systematically assay the elements that drive expression in core- and proximal-promoter regions and shed light on organization principles of regulatory regions in the human genome.

scholarly journals Decoding a Signature-Based Model of Transcription Cofactor Recruitment Dictated by Cardinal Cis-Regulatory Elements in Proximal Promoter Regions

PLoS Genetics ◽  
2013 ◽  
Vol 9 (11) ◽  
pp. e1003906 ◽  
Author(s):  
Christopher Benner ◽  
Sergiy Konovalov ◽  
Carlos Mackintosh ◽  
Kasey R. Hutt ◽  
Rieka Stunnenberg ◽  
...  
Keyword(s):  
Regulatory Elements ◽  
Proximal Promoter ◽  
Promoter Regions ◽  
Transcription Cofactor ◽  
Cofactor Recruitment

scholarly journals Identification of regulatory elements in the Cyp19 proximal promoter in rat luteal cells

2007 ◽  
Vol 39 (4) ◽  
pp. 211-221 ◽  
Author(s):  
Carlos Stocco ◽  
Jakub Kwintkiewicz ◽  
Zailong Cai
Keyword(s):  
Binding Site ◽  
Promoter Activity ◽  
Regulatory Elements ◽  
Binding Activity ◽  
Proximal Promoter ◽  
Promoter Regions ◽  
Pregnant Rats ◽  
Response Element ◽  
Luteal Cells ◽  
Immature Rats

AbstractThe cytochrome P450 aromatase (Cyp19) gene encodes an enzyme of crucial importance in the synthesis of estradiol. Estradiol is luteotropic in the rat. In this species, luteal Cyp19 expression increases progressively during pregnancy and falls before parturition. The mechanisms that control these changes are unknown. Using gel shift assays, we sought to identify the promoter regions that control Cyp19 expression in the rat corpus luteum (CL). The Cyp19 promoter contains a cAMP response element-like sequence (CLS), two nuclear receptor elements half sites (NREs), a GATA binding site, a Yin Yang-1 (YY1) response element, and an activation protein 3 (AP3) binding site. Nuclear extracts were obtained from CL of rats on days 4, 15, and 23 of pregnancy and from the ovaries of immature rats treated with vehicle or a hormone that induces Cyp19 expression in the follicles. CLS was active in immature ovaries but inactive in the CL of pregnant rats, whereas binding to NREs and GATA was observed in both tissues. YY1 was inactive in all samples tested. In the CL, AP3 binding was higher on day 15 of pregnancy when compared with day 4 and day 23 but it was absent in ovaries of immature rats, whereas luteinization increased AP3 binding activity. Mutation of the AP3 site blunted the stimulation of Cyp19 promoter activity in granulosa cells. Our results indicate that CLS is active only in follicles; whereas in the CL, binding to the GATA, NRE, and AP3 sites associates with changes in Cyp19 expression, suggesting that they control Cyp19 promoter activity in luteal cells.

Preceding Stimulus Frequency-Dependent Potentiation of the Postrest Shortening of the Action Potential Duration in Rabbits.

2000 ◽  
Vol 41 (4) ◽  
pp. 481-492
Author(s):  
Naohiko Takahashi ◽  
Morio Ito ◽  
Shuji Ishida ◽  
Takao Fujino ◽  
Mikiko Nakagawa ◽  
...  
Keyword(s):  
Action Potential ◽  
Action Potential Duration ◽  
Stimulus Frequency ◽  
Frequency Dependent ◽  
Preceding Stimulus

scholarly journals P496Remodeling of atrial action potential duration and atrial chamber deformation: a potential link in the development of atrial fibrillation?

2018 ◽  
Vol 114 (suppl_1) ◽  
pp. S120-S120
Author(s):  
L Sartiani ◽  
L Sartiani ◽  
M Cameli ◽  
L Dini ◽  
S Modillo ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Action Potential ◽  
Action Potential Duration ◽  
Potential Link

scholarly journals The Coordinated Upregulated Expression of Genes Involved in MEP, Chlorophyll, Carotenoid and Tocopherol Pathways, Mirrored the Corresponding Metabolite Contents in Rice Leaves during De-Etiolation

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1456
Author(s):  
Xin Jin ◽  
Can Baysal ◽  
Margit Drapal ◽  
Yanmin Sheng ◽  
Xin Huang ◽  
...  
Keyword(s):  
Higher Plants ◽  
Expression Patterns ◽  
Regulatory Elements ◽  
Isoprenoid Biosynthesis ◽  
Promoter Regions ◽  
Expression Of Genes ◽  
Coordinated Expression ◽  
Rice Leaves ◽  
Mechanistic Basis ◽  
Phosphate Synthase

Light is an essential regulator of many developmental processes in higher plants. We investigated the effect of 4-hydroxy-3-methylbut-2-enyl diphosphate reductase 1/2 genes (OsHDR1/2) and isopentenyl diphosphate isomerase 1/2 genes (OsIPPI1/2) on the biosynthesis of chlorophylls, carotenoids, and phytosterols in 14-day-old etiolated rice (Oyza sativa L.) leaves during de-etiolation. However, little is known about the effect of isoprenoid biosynthesis genes on the corresponding metabolites during the de-etiolation of etiolated rice leaves. The results showed that the levels of α-tocopherol were significantly increased in de-etiolated rice leaves. Similar to 1-deoxy-D-xylulose-5-phosphate synthase 3 gene (OsDXS3), both OsDXS1 and OsDXS2 genes encode functional 1-deoxy-D-xylulose-5-phosphate synthase (DXS) activities. Their expression patterns and the synthesis of chlorophyll, carotenoid, and tocopherol metabolites suggested that OsDXS1 is responsible for the biosynthesis of plastidial isoprenoids in de-etiolated rice leaves. The expression analysis of isoprenoid biosynthesis genes revealed that the coordinated expression of the MEP (2-C-methyl-D-erythritol 4-phosphate) pathway, chlorophyll, carotenoid, and tocopherol pathway genes mirrored the changes in the levels of the corresponding metabolites during de-etiolation. The underpinning mechanistic basis of coordinated light-upregulated gene expression was elucidated during the de-etiolation process, specifically the role of light-responsive cis-regulatory motifs in the promoter region of these genes. In silico promoter analysis showed that the light-responsive cis-regulatory elements presented in all the promoter regions of each light-upregulated gene, providing an important link between observed phenotype during de-etiolation and the molecular machinery controlling expression of these genes.

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