# Cracking the signaling code: how ERK activity dynamics coordinate gene expression and differentiation in keratinocytes

> **NIH NIH F31** · PRINCETON UNIVERSITY · 2020 · $45,520

## Abstract

Project Summary:
The development and maintenance of epithelial organs on a cellular level is reliant upon concerted networks of
biochemical signaling pathways, which transmit environmental cues such as growth factor and calcium
concentrations to the level of gene expression in the cell. One example is basal keratinocytes, which have
important proliferative and differentiation roles in the body. The precise regulation of these behaviors
establishes the spatial axis of differentiated cells that makes up the skin. Both proliferative and differentiation
cell behaviors have been linked to Ras/ERK MAP kinase pathway signaling; however, the precise mechanisms
through which the same pathway regulates both responses remain unclear. Moreover, with an increasing body
of work suggesting that epidermal progenitor cells may someday be used to culture patient-specific skin grafts
in a dish, an understanding of single-cell signaling dynamics becomes increasingly important in dissecting the
emergent tissue level behavior. Our lab has introduced live reporters of ERK activity into primary mouse
keratinocytes and found that ERK demonstrates rich, complex endogenous dynamics. The objective of this
proposal is to understand if and how Ras/ERK pathway dynamics in keratinocytes are read out at the level of
cellular behavior, resulting in either proliferation or differentiation. I will use a combination of live cell reporter
imaging, single-cell imaging of transcriptional dynamics, and engineering of synthetic reporter genes to dissect
how ERK activity dynamics feed into the ERK-downstream gene expression program. To control
physiologically relevant ERK behavior, I will use a combination of organotypic cell culture and optogenetic
inputs. These approaches will be used in concert to probe input-output functions of ERK dynamics to gene
expression, to test the hypothesis that different dynamic ERK behaviors are read out in different gene
expression programs. A successful completion of the proposed work will constitute the first detailed dissection
of ERK dynamics in a primary cell context as well as mapping of these dynamics to outputs in the form of
physiologically relevant gene expression and cell responses. A comprehensive understanding of live signaling
dynamics in differentiating, proliferating skin will likely have a broad impact on tissue engineering, regenerative
medicine, and a deeper fundamental understanding of epithelial organs.

## Key facts

- **NIH application ID:** 10000760
- **Project number:** 5F31AR075398-02
- **Recipient organization:** PRINCETON UNIVERSITY
- **Principal Investigator:** Siddhartha Jena
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $45,520
- **Award type:** 5
- **Project period:** 2019-08-01 → 2021-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10000760

## Citation

> US National Institutes of Health, RePORTER application 10000760, Cracking the signaling code: how ERK activity dynamics coordinate gene expression and differentiation in keratinocytes (5F31AR075398-02). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10000760. Licensed CC0.

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