Difference between revisions of "Part:BBa K5267006"

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6xCRE-Pmin

As the response element to report whether melatonin is accepted or not Sequence and Features

Profile

Name: 6xCRE-Pmin
Base Pairs: 159bp
Origin: Homo sapiens
Properties: As the response element to report whether melatonin is accepted or not

Usage and Biology

CRE(cAMP response element)play an important role as the binding site of CREB(cAMP response element binding protein) ,which is typically found within 100 nucleotides of the TATA Box. CREB binds to cAMP response elements and recruits transcriptional coactivators (such as CBP/p300) to form transcription complexes that initiate transcription of target genes.[1]

TATA Box is one of the components that constitute the promoter of eukaryotes. The consistent order is TATA(A/T)A(A/T) (non-template chain sequence). It is about -30bp (-25~-32bp) upstream of the transcription starting point of most eukaryotic genes, and is basically composed of A-T base pairs, which determines the selection of gene transcription and is one of the binding sites of RNA polymerase. RNA polymerase can only start transcription after firmly binding to the TATA Box. The ability of CRE sequences to mediate transcriptional activation in response to cAMP appears to be somewhat promoter dependen[1],in this experiment, TATA box of the commonly used CMV promoter was selected to minimize to the minimum amount of nucleotides for transcription and named Pmin.

The activity of CREB is modulated by a plethora of signaling cascades, including three downstream pathways that are activated by the melatonin receptor MT1/2 in response to melatonin stimulation: the cAMP/PKA pathway, the calcium (Ca2+) signaling pathway, and MAPK/ERK pathway.[2] Consequently, CRE can be employed as a diagnostic element to assess the successful activation of the melatonin receptor's downstream signaling pathways.

Special design

In part 4xCRE-Pmin (BBa_K5267004), we demonstrated that CRE can promote downstream gene transcription after binding to CREB. However, we cannot be sure that 4 multimerized CRE sequence incorporating a 5'minimal promoter is the best choice to promote expression. In order to select the best number of clones，in this parts ，we constructed the 6xCRE-Pmin sequence, containing a 5'minimal promoter with 6 multimerized CREs.

Function test

In order to test the function of cAMP response element, multiple CRE sequences and Pmin were loaded onto vector that equipped with sleeping beauty transposon site, where IgK-Nluc reporter gene added downstream. If the incandescent sequence responds successfully, the Nluc gene will be successfully expressed. (Figure 1)
In Figure 1,we can find that the expression level of Nluc gene in cells supplemented with 4XGRE-Pmin was significantly increased compared with the blank control, which proved that the CRE sequence responded successfully.

Sequence

cagcctgacgtccgagtcgcgtagcctgacgtccgagagccgtagcctgacgtccgagggtaccagcctgacgtccgagagccgtagcctgacgtccgagtactccgtagagggtatataatggaagctcgacttccag

Reference

[1] M. Montminy, "Transcriptional regulation by cyclic AMP," Annu Rev Biochem, vol. 66, pp. 807-22, 1997, doi: 10.1146/annurev.biochem.66.1.807.
[2] A. J. Shaywitz and M. E. Greenberg, "CREB: a stimulus-induced transcription factor activated by a diverse array of extracellular signals," Annu Rev Biochem, vol. 68, pp. 821-61, 1999, doi: 10.1146/annurev.biochem.68.1.821.