# Molecular Mechanisms in the Arabidopsis Circadian Clock

> **NIH NIH R37** · UNIVERSITY OF SOUTHERN CALIFORNIA · 2024 · $446,350

## Abstract

Organisms living on Earth cope daily with changes in their environment. An endogenous oscillator, known
as the circadian clock, enables organisms to coordinate metabolism, physiology, and development in
 anticipation of diurnal and seasonal environmental changes and therefore, enhances fitness. The
molecular network underlying the circadian system relies on interlocked transcriptional-translational
feedback loops, in addition to multiple layers of regulation at the cellular and organismal level. We
 propose to deploy a combination of genetic, molecular, biochemical, physiological, bioinformatic, and
genome-wide approaches to identify new components of the clockwork, and unravel the intricate wiring of
the circadian clock in Arabidopsis.
TOC1 is a key element of the core-clock of Arabidopsis. Recent data from our laboratory have shown that
TOC1 binds to RNA in vitro. We propose to validate this biochemical property in vivo and study its
biological relevance. We will also characterize TOC1 association with the transcriptional machinery and
 with hub components of hormone signaling pathways, which will be instrumental to understand the role of
TOC1 in the circadian system. We further seek to explore the GI molecular network and propose to
combine molecular, genetic, and biochemical analyses to study novel partners including transcription
factors associated with pathogen responses, hormone and growth signaling. Preliminary data from our
 laboratory also suggest a potential role of the circadian clock in nitrate uptake. We aim to characterize
nitrate uptake dynamics and by utilizing genetic, biochemical, and physiological studies we seek to
 identify the molecular mechanisms underlying the potential regulation of root physiology by the
endogenous clock.
 By integrating different approaches including bioinformatic, classic plant photobiology tools and mutant
screens, we propose to elucidate three distinct layers of the clock: to uncover the signaling pathway of
light input to the clockwork; to identify new core-clock elements; and to discover components that are
 necessary for the oscillator to achieve different developmental or physiological traits.
 Mechanistic details from our study can be extrapolated outside the circadian field to advance research of
 other complex regulatory systems and ultimately impact work in human health, disease, and food security.
D
RELEVANCE (See instructions):
 This proposal will improve our insights of plant physiology and will provide a comprehensive
 understanding of the circadian system and the cellular processes associated with it. The study will
 ultimately impact research in human biological rhythms and treatment of circadian-linked health disorders.

## Key facts

- **NIH application ID:** 10753440
- **Project number:** 5R37GM067837-22
- **Recipient organization:** UNIVERSITY OF SOUTHERN CALIFORNIA
- **Principal Investigator:** STEVE A KAY
- **Activity code:** R37 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $446,350
- **Award type:** 5
- **Project period:** 2003-06-01 → 2026-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10753440

## Citation

> US National Institutes of Health, RePORTER application 10753440, Molecular Mechanisms in the Arabidopsis Circadian Clock (5R37GM067837-22). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10753440. Licensed CC0.

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