# Architecture and function of striatal dopamine release machinery

> **NIH NIH R01** · HARVARD MEDICAL SCHOOL · 2020 · $514,715

## Abstract

Summary
Dopamine is an important neuromodulator and pathologies in dopamine signaling are a hallmark of brain
diseases such as neurodegeneration, substance abuse, and schizophrenia. Despite these important roles for
dopamine, remarkably little is known about the molecular mechanisms of its release. Because dopamine acts
as a volume transmitter, it is not clear whether dopamine release involves molecular machinery that warrants
spatial and temporal precision for release. Alternatively, dopamine release could be spread over the surface of
an axon, which is consistent with volume transmission. The release of classical transmitters relies on an active
zone, a highly organized protein structure that contains scaffolding proteins such as RIM and ELKS and
determines the precise localization, speed and accuracy of synaptic vesicle exocytosis. The active zone also
provides mechanisms for regulation of release during plasticity. Our preliminary experiments reveal that the
presynaptic scaffolding protein RIM is absolutely required for dopamine release in the mouse striatum, but that
ELKS is dispensable for dopamine release. This is different from classical fast synapses, where knockout of
either protein family leads to a reduction of 50-80% of release. We thus hypothesize that dopamine release
necessitates mechanistically specialized release sites. This hypothesis is bolstered by superresolution
microscopy in striatal brain slices, which shows that several release site scaffolding proteins are clustered
inside dopamine axons. We pursue a two-pronged approach to address this central hypothesis. In aim one, we
use rigorous conditional mouse genetics and electrophysiology in acute brain slices of the mouse striatum to
systematically address the necessity of scaffolding proteins, priming proteins and Ca2+ channel tethers in
dopamine release and in co-release of GABA and glutamate from dopamine neurons. This is the first study on
the requirements of molecular scaffolds for dopamine secretion and it will lead to a comprehensive assessment
of the dopamine release machinery. In aim two, we assess whether scaffolding proteins mediate dopamine
secretion as soluble release factors, or whether they are assembled in clustered release sites to target
dopamine release to specific membrane domains. The latter possibility is strongly supported by our preliminary
data. We will combine superresolution microscopy, subcellular fractionation, electron microscopy and mouse
genetics to study the existence and composition of dopamine release sites in the mouse striatum. We will
assess how dopamine release sites are associated with vesicle clusters, with receptors for dopamine and for
the co-transmitters GABA and glutamate, and with cholinergic innervation, which powerfully triggers dopamine
release. These experiments will establish the existence, appearance and composition of dopamine release
sites and their structural arrangement into striatal synaptic microcircuits. Our approach ...

## Key facts

- **NIH application ID:** 9915988
- **Project number:** 5R01NS103484-04
- **Recipient organization:** HARVARD MEDICAL SCHOOL
- **Principal Investigator:** Pascal Simon Kaeser
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $514,715
- **Award type:** 5
- **Project period:** 2017-08-01 → 2022-03-14

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9915988

## Citation

> US National Institutes of Health, RePORTER application 9915988, Architecture and function of striatal dopamine release machinery (5R01NS103484-04). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/9915988. Licensed CC0.

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