# Molecular mechanisms of mammalian circadian clock function

> **NIH NIH R35** · UT SOUTHWESTERN MEDICAL CENTER · 2024 · $214,475

## Abstract

Abstract
Circadian clocks throughout the body drive rhythmic expression of thousands of genes, resulting in
rhythms in biochemistry, physiology and behavior. Disruption of circadian clocks through genetics or
environmental perturbations such as jet lag or shift-work, can have profound negative consequences
and has been linked to obesity, diabetes, cancer, cardiovascular disease and mental illness. In
particular, circadian clocks exert control over nearly every major metabolic pathway, allowing optimal
utilization of typically cyclic availability of nutrients. Our work is focused generally on
understanding the detailed molecular mechanisms of the mammalian circadian clock
machinery and the mechanisms by which these clocks control rhythmic metabolism. In this
Equipment Supplement request, we seek funds to purchase an integrated plate reader system that
allows determination of fluorescence and luminescence signals both in a typical plate reader fashion
(total signal per well) and also as high quality and high-resolution images due to the integrated
spinning disk confocal microscope. Because of the built-in CO2 incubator with temperature control
and shaker, this piece of equipment will allow us to measure circadian rhythms of gene expression or
metabolites continuously for many days – a requirement for assessing circadian periodicity. Our
studies on the central clock mechanism require careful determination of circadian period length,
amplitude and phase following different experimental manipulations and this reader will allow these
measurements in multi-well format. The sophisticated time-resolved fluorescence and fluorescence
polarization detection will allow the quantitative analysis of protein-protein interactions within the clock
mechanism. In addition, our work on circadian control of metabolism is focused on the control of
NAD(H) and NADP(H) by the circadian NADP(H) phosphatase Nocturnin. Nocturnin is present in two
forms, a mitochondrial form and a cytosolic form that is myristoylated and associates with ER and
other intracellular membranes. In order to determine the role Nocturnin plays in controlling these
metabolites, it is necessary to examine their levels in different intracellular compartments. Because
this plate reader system has spinning disk confocal imaging capabilities, this will allow us to use
NADP(H) fluorescent sensors to follow the flux of NADP(H) and other associated metabolites over
time in different organelles and subcellular locations over time and in response to perturbations in the
clock. These types of experiments are currently impossible since the NADP(H) measurements
cannot be done on a normal confocal microscope and require a spinning disk (we do not have access
to a spinning disk confocal within our department). Furthermore, the length of the experiments and
the need for high throughput require a dedicated instrument. In conclusion, this piece of equipment
will have a major impact on both of the main objectives of ou...

## Key facts

- **NIH application ID:** 11098391
- **Project number:** 3R35GM127122-07S1
- **Recipient organization:** UT SOUTHWESTERN MEDICAL CENTER
- **Principal Investigator:** Carla B. Green
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $214,475
- **Award type:** 3
- **Project period:** 2018-08-07 → 2028-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11098391

## Citation

> US National Institutes of Health, RePORTER application 11098391, Molecular mechanisms of mammalian circadian clock function (3R35GM127122-07S1). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/11098391. Licensed CC0.

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