# Delineating the Biology of Translational Repressor 4E-BP1

> **NIH NIH R01** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2021 · $312,000

## Abstract

Eukaryotic translation initiation factor (eIF4E)-binding protein 1 (4E-BP1) is an intrinsically disordered protein
that functions as the gate-keeper of cap-dependent mRNA translation, the process by which mRNA transcripts
containing a m7G cap at their 5’ terminus are converted into protein. As cap-containing mRNAs predominantly
encode for growth and survival factors, the role of 4E-BP1 in cell biology is significant and aberrant 4E-BP1
activity has been linked to cancer, neurodegenerative diseases and metabolic disorders among others. 4E-BP1
is regulated by phosphorylation: hypophosphorylated 4E-BP1 binds strongly to eIF4E, the m7G cap-binding
translation initiation factor, to inhibit translation, while hyperphosphorylated 4E-BP1 releases eIF4E to initiate
translation. To date, the only kinase known to affect 4E-BP1 phosphorylation is mechanistic target of rapamycin
complex 1 (mTORC1); however, reports have demonstrated that other unknown kinases can also phosphorylate
4E-BP1 to stimulate cap-dependent translation, particularly in cases of mTORC1 inhibition. In order to identify
these kinases, we have developed an unbiased, chemoproteomic approach for identifying high confidence
kinase-substrate interactions with phosphosite specificity. Using this assay, we have uncovered the role of cyclin-
dependent kinase 4 (CDK4), a clinically validated kinase important for cell cycle progression, in driving cap-
dependent translation via phosphorylation of 4E-BP1. Importantly, this work constitutes the first example of
successful kinase discovery using an activity-based, kinase-directed probe. As 4E-BP1 is phosphorylated at as
many as 13 unique sites, we hypothesize that many other kinases signal to and regulate 4E-BP1. Additionally,
despite the critical role of 4E-BP1 phosphorylation in protein synthesis, few studies have been disclosed
regarding the biological function of each of its phosphorylated serine and threonine residues, including its orphan
sites known to be unaffected by mTORC1. To fill in these knowledge gaps, the Specific Aims of this proposal
are as follows: (1) To determine the molecular details of CDK4-mediated 4E-BP1 hyperphosphorylation; (2) To
determine the functional and mechanistic significance of CDK4-mediated 4E-BP1 hyperphosphorylation; and (3)
To identify and validate additional kinases acting on 4E-BP1 using chemoproteomics. Through these studies,
we will not only further enhance our knowledge of 4E-BP1-mediated translational regulation, but also illuminate
new druggable targets for treatment of the many diseases associated with aberrant cap-dependent translation.

## Key facts

- **NIH application ID:** 10244869
- **Project number:** 5R01GM132342-02
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** Amanda Garner
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $312,000
- **Award type:** 5
- **Project period:** 2020-09-01 → 2024-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10244869

## Citation

> US National Institutes of Health, RePORTER application 10244869, Delineating the Biology of Translational Repressor 4E-BP1 (5R01GM132342-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10244869. Licensed CC0.

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