Biology subjects

Cui, J. H.

Publications and source records attributed to Cui, J. H..

3 recordsLinked to original sources

bioRxiv2025

Molecular determinants underlying functional divergence of TBP homologs

The TATA-box binding protein (TBP) is a highly conserved basal transcription factor and a core component of the pre-initiation complex (PIC) for all three eukaryotic RNA polymerases (RNA Pols). Despite this conservation, TBP function diverges across species. In yeast, TBP is required for all three RNA Pols, whereas in mammals, it is essential only for RNA Pol III, but not RNA Pol I or II. To examine the evolutionary divergence of TBP homologs in different species, we determined the ability of murine TBP and its paralogs to complement endogenous TBP in Saccharomyces cerevisiae. Despite their highly conserved DNA-binding domains, murine TBP homologs were unable to fully rescue the lethality caused by TBP inactivation in yeast. This incomplete complementation correlates with a failure to fully support binding by RNA Pols II and III. Furthermore, we show that the divergent N-terminal domain (NTD) of TBP contributes to species-specific activity and modulates RNA Pol II binding changes in stress-induced response. Lastly, we demonstrate a negative correlation between the length of the intrinsically disordered NTD of TBP family proteins and the gene density in different species, suggesting that the NTD may have contributed to increasingly complex gene regulation during evolution.

molecular biology↗

bioRxiv2024

Dynamic regulation of RNA Polymerase III transcription in mouse embryonic stem cells during heat shock stress

Cells respond to many different types of stresses by overhauling gene expression patterns, both at the transcriptional and translational level. Under heat stress, global transcription and translation are inhibited, while the expression of chaperone proteins are preferentially favored. As the direct link between mRNA transcription and protein translation, tRNA expression is intricately regulated during the stress response. Despite extensive research into the heat shock response (HSR), the regulation of tRNA expression by RNA Polymerase III (Pol III) transcription has yet to be fully elucidated in mammalian cells. Here, we examine the regulation of Pol III transcription during different stages of heat shock stress in mouse embryonic stem cells (mESCs). We observe that Pol III transcription is downregulated after 30 minutes of heat shock, followed by an overall increase in transcription after 60 minutes of heat shock. This effect is more evident in tRNAs, though other Pol III gene targets are also similarly affected. Notably, we show that the downregulation at 30 minutes of heat shock is independent of HSF1, the master transcription factor of the HSR, but that the subsequent increase in expression at 60 minutes requires HSF1. Taken together, these results demonstrate an adaptive RNA Pol III response to heat stress, and an intricate relationship between the canonical HSR and tRNA expression. Article SummaryThis study explores the regulation of RNA Polymerase III (Pol III) transcription during heat shock in mouse embryonic stem cells (mESCs). Results show that tRNA transcription is downregulated after 30 minutes of heat shock, but increases after 60 minutes, while other Pol III targets remain unaffected. Importantly, the initial downregulation is independent of heat shock factor 1 (HSF1), the key regulator of the heat shock response, but the subsequent increase in tRNA expression depends on HSF1. These findings reveal an adaptive mechanism of Pol III activity under heat stress, highlighting a complex interplay between heat shock response and tRNA expression.

molecular biology↗

bioRxiv2024

Functional divergence of TBP homologs through distinct DNA binding dynamics

The TATA box-binding protein (TBP) is an evolutionarily conserved basal transcription factor common in the pre-initiation complex of all three eukaryotic RNA polymerases (RNA Pols). Despite their high conservation, homologous TBPs exhibit species- and tissue-specific functions that may contribute to the increasingly complex gene expression regulation across evolutionary time. To determine the molecular mechanisms of species- and tissue-specificity for homologous TBPs, we examined the ability of yeast TBP and murine TBP paralogs to replace the endogenous TBP in mouse embryonic stem cells. We show that, despite the high conservation in the DNA binding domain among the homologs, they cannot fully rescue the lethality of TBP depletion in mESCs, largely due to their inability to support RNA Pol III transcription. Furthermore, we show that the homologs differentially support stress-induced transcription reprogramming, with the divergent N-terminal domain playing a role in modulating changes in transcriptional response. Lastly, we show that the homologs have vastly different DNA binding dynamics, suggesting a potential mechanism for the distinct functional behavior observed among the homologs. Taken together, these data show a remarkable balance between flexibility and essentiality for the different functions of homologous TBP in eukaryotic transcription.

molecular biology↗