# Admin Supplement - Signaling by the EGF Receptor from Endosomes

> **NIH NIH R01** · UNIVERSITY OF PITTSBURGH AT PITTSBURGH · 2020 · $69,255

## Abstract

Abstract of Parental Grant GM124186
 Elucidation of the mechanisms by which endocytic trafficking regulates signal transduction processes
remains to be profoundly important for understanding how diverse stimuli propagate signals from the cell surface
through the conserved cytosolic machinery and to the nucleus leading to a stimulus- and context-specific
signaling outcome. Epidermal growth factor (EGF) receptor (EGFR), a prototypic receptor tyrosine kinase, has
been the major experimental model to study spatiotemporal regulation of signaling networks. EGFR plays an
essential role in mammalian development and tissue homeostasis in the adult, and is involved in human
pathogenesis, in particular, cancer. However, while the main constituents of the EGFR signaling network are
known, how they coordinately function during EGFR endocytosis and subsequent targeting of receptors for
degradation to endosomes to ensure proper intensity and duration of signaling processes is for the large part
unknown.
 Addressing this fundamental question has now become possible owing to the availability of new cutting-
edge methodologies. Using time-resolved quantitative mass-spectrometry of cellular phosphoproteomes we
found that after the majority of active EGFRs are internalized into endosomes, phosphorylation of a multitude of
proteins, known to be involved in the regulation of signaling to growth, survival, cell motility and adhesion, is
maintained by EGFR. Therefore, we hypothesize that the pathways involving these putative signaling effectors
of EGFR operate in endosomes through the sustained activity of endosomal EGFR. We further hypothesize that
by maintaining the activity along some signaling pathways while down-regulating other pathways, EGFR
endocytosis shapes the overall functional outcome of EGFR signaling.
 To test these hypothesis in the physiological experimental system (cells that are growth-dependent on
EGFR) we will: 1) examine whether putative substrates and signaling effectors of endocytosed EGFR identified
by the phosphoproteomic analysis are located in EGFR-containing endosomes by labeling endogenous effectors
with fluorescent proteins by gene-editing and dissecting their time-dependent localization dynamics using multi-
dimensional fluorescence microscopy imaging; and 2) examine whether endocytosis and localization in
endosomes control downstream signaling activity of putative phosphorylation substrates and effectors of
endosomal EGFR, and define the mechanisms of this regulation. Combination of the high-throughput method of
labeling endogenous proteins by gene-editing with various methods of quantitative live-cell optical imaging at all
levels of resolution will allow us to apply a systems biology approach to untangling the entire endosomal signaling
program.

## Key facts

- **NIH application ID:** 10133844
- **Project number:** 3R01GM124186-03S1
- **Recipient organization:** UNIVERSITY OF PITTSBURGH AT PITTSBURGH
- **Principal Investigator:** ALEXANDER D SORKIN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $69,255
- **Award type:** 3
- **Project period:** 2017-09-15 → 2021-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10133844

## Citation

> US National Institutes of Health, RePORTER application 10133844, Admin Supplement - Signaling by the EGF Receptor from Endosomes (3R01GM124186-03S1). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10133844. Licensed CC0.

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