# Regulation of transcription by the Mediator complex

> **NIH NIH R35** · TRUSTEES OF INDIANA UNIVERSITY · 2020 · $393,750

## Abstract

PROJECT SUMMARY/ABSTRACT
Mediator is a conserved, essential regulator of RNA Polymerase II (RNAPII) transcription that is proposed to
function as a connector between distal regulatory elements and gene-proximal promoters. This bridging
depends on two distinct modules of Mediator: the tail, which interacts with transcriptional activators bound to
specific DNA sequences at a distal regulatory element, and the head, which interfaces with the promoter-
associated basal transcription machinery. A major outcome of this bridging activity of Mediator is thought to be
a positive impact on the formation of the RNAPII pre-initiation complex (PIC). Using ChEC-seq, a method that
we introduced for global mapping of protein-DNA interactions, we elucidated a role for Mediator in the
recruitment of the TFIID complex, a component of the PIC, to the majority of promoters in the yeast genome.
We propose to expand on this finding via a thorough characterization of the role of Mediator in the recruitment
of each subcomponent of the PIC, which will yield a comprehensive view of the role of Mediator in PIC
formation in vivo. While composed of over two dozen subunits, Mediator has been proposed to be generally
monolithic. However, there is evidence that the tail module might have functions independent of the complete
Mediator complex, though this has not been rigorously tested. We will investigate the transcriptional effects of
severing the Mediator tail from the complex as well as the transcriptional consequences of removing the tail
after it has been severed. Lastly, we propose to expand our studies of Mediator beyond yeast and into
mammalian cells, where Mediator associates with distal enhancer elements. While the association of Mediator
with enhancers is well known, it is unclear if its role as a transcriptional regulator extends to the transcription of
enhancer RNAs (eRNAs). We will thus determine the effects of Mediator depletion on eRNA transcription as
well as PIC formation at enhancers. The critical role of Mediator in transcriptional regulation is underscored by
the numerous human disorders linked to its dysregulation: point mutations in various Mediator subunits have
been implicated in several neurodevelopmental disorders, and alterations in Mediator subunit expression have
been observed in a wide variety of cancers. The fundamental insights into Mediator function gained through
this work will therefore enhance not only our understanding of the core functions of Mediator but also why its
dysregulation is so often observed in disease.

## Key facts

- **NIH application ID:** 9979883
- **Project number:** 5R35GM128631-03
- **Recipient organization:** TRUSTEES OF INDIANA UNIVERSITY
- **Principal Investigator:** GABRIEL ZENTNER
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $393,750
- **Award type:** 5
- **Project period:** 2018-08-01 → 2023-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9979883

## Citation

> US National Institutes of Health, RePORTER application 9979883, Regulation of transcription by the Mediator complex (5R35GM128631-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9979883. Licensed CC0.

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