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Transcription Factors and Their Libraries
Release time:
2025-02-06
Transcription factors (TFs) are proteins that bind to specific regions of DNA (called transcription factor binding sites) and regulate gene transcription. Transcription factors can influence gene expression, thereby affecting aspects like cell growth, differentiation, and function.
A transcription factor library is a collection of various transcription factors, which is an important tool for studying gene regulatory networks. It helps to understand how specific transcription factors interact with other proteins to regulate gene expression and respond to different biological processes.
Principle Overview
Transcription factor libraries can be used for Y1H screening to identify transcription factors that regulate promoters, or for standard nuclear protein Y2H screening to identify transcription factors interacting with them.
The principles of both are similar. The yeast GAL4 protein is a typical transcription factor, with its DNA-binding domain near the C-terminal and containing several zinc finger structures. It can activate the upstream activation site (UAS) of the yeast β-galactosidase gene, while the transcription activation domain interacts with RNA polymerase or transcription factor TFIID to enhance RNA polymerase activity.
In this process, the DNA-binding domain and the transcription activation domain can function independently. Therefore, we can link the GAL4 DNA-binding domain to the target gene as a bait plasmid to screen the transcription factor library, effectively identifying transcription factors that interact with the target gene.
Application Case
Previously, Arabidopsis transcription factor libraries were often used to study transcription factors interacting with other transcription factors or cis-regulatory elements.
The application of transcription factor libraries in different species is similar. Below is an example from the literature to illustrate the use of transcription factor libraries.
Area 1 TOP IF = 7.2
1.Research Background
The endoplasmic reticulum (ER) stress response (UPR) in maize is a cellular response to the accumulation of unfolded or misfolded proteins in the ER. Under adverse environmental conditions such as extreme weather or pathogen attacks, crop yields can be severely affected because these conditions increase the demand for protein folding, exceeding the biosynthetic capacity of the ER, leading to a potentially lethal condition called ER stress.
UPR is a series of highly conserved surveillance pathways designed to clear misfolded proteins in the ER. Understanding UPR is crucial for maintaining and potentially improving crop yields, especially as the global population is projected to reach 9 billion by 2050, requiring crop yields to double to meet food demand. However, little is known about how UPR target genes are transcriptionally regulated during ER stress, particularly in crops like maize.
2.Research Content
Identification of PDI behind UPR gene expression dynamics
While many transcriptional changes in UPR have been identified in multiple species, the identity and dynamics of the gene regulatory hubs behind the ER stress response remain undrawn. To identify these regulatory hubs, RNA-seq datasets from maize roots under ER stress were analyzed. Six UPR target genes were selected based on their unique expression features during ER stress, which are directly related to important cellular metabolic processes required for ER homeostasis.
To establish the UPR target gene-transcription factor regulatory network, the maize transcription factor library was used for enhanced yeast one-hybrid (eY1H) screening, successfully identifying 262 transcription factors and 831 protein-DNA interactions (PDIs). These PDIs involved transcription factors binding to the promoters of UPR target genes, revealing the combinatorial effects of multiple transcription factors that lead the expression dynamics of UPR target genes. The study also discovered new potential PDIs, which were compared with ChIP-seq datasets to validate the accuracy of the screening method.
Downstream Validation Cases
Due to the influence of multiple factors, the results from a single yeast one-hybrid assay may not fully prove the interaction status of a transcription factor. From the literature mentioned above, we observed that the interactions identified from transcription factor library screening were validated using ChIP-seq datasets.
So, what are some commonly used validation experiments? Let’s learn about them through the following literature examples.
Figure 1: OsPHR2 Directly Regulates the Expression of Mycorrhizal-Related Genes through the P1BS Element
The authors confirmed through EMSA and luciferase reporter assays that OsPHR2 can directly bind and activate the promoters of OsRAM1, OsWRI5A, OsPT11, and OsAMT3, and this binding is dependent on the P1BS element in the promoter.
Figure 2: In vitro Confirmation of TFs Interacting with Med25 and the GCC-Box of the PDF1.2 Promoter
Med25/PFT1 is considered a key regulatory factor in Arabidopsis JA-dependent defense. The authors used the transcription factor library to identify TFs that interact with Med25 and the PDF1.2 promoter, confirming the interaction through GST pull-down and EMSA assays.
Figure 3: Cytokinin Response Factor Interacts with PCRE
The authors used co-immunoprecipitation and quantitative PCR to detect the interaction between cytokinin response factors and PCRE.
From these cases, we can see that after library screening, ChIP, EMSA, and dual-luciferase reporter assays are commonly used to validate the results. Based on these validation results, further transcription factor interaction analysis and mechanism studies can be conducted.
Technical Introduction
In previous transcription factor research, the Arabidopsis transcription factor library has been widely used across various species. However, due to species differences, it is often difficult to guarantee good research outcomes.
With the gradual establishment of transcription factor libraries for other species, such as the full-length rice transcription factor library, the study of transcription factors in rice has been greatly advanced. Based on this library, a transcription factor regulatory network for rice has been successfully constructed.
Pronetbio has launched the maize full-length transcription factor library and provides a series of supporting products and services to assist maize transcription factor research!
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