Investigating a Newly Discovered Aspect of Dopamine Signaling

About This Grant

PROJECT SUMMARY/ABSTRACT This proposal emerges from the discovery that the D1 family of dopamine receptors, a class of G protein coupled receptor (GPCR), long considered to only signal from the plasma membrane, also signal from the Golgi membranes. This subcellular and compartmentalized signaling challenges some of the basic paradigms of signaling regulation. D1 dopamine receptors are the main GPCR in the midbrain and regulate functions such as locomotion, cognition, attention and impulse control. Several pathological conditions including Parkinson's disease, schizophrenia and addiction are due to dysregulation of this signaling pathway. Many drugs of abuse promote dopaminergic transmission within the midbrain by increasing the release of dopamine and activating D1 dopamine receptors, D1DRs. This increased activity of midbrain dopaminergic neurons results in increased locomotor activity and motivational behaviors such as craving and drug-seeking. In all of these studies, it has been assumed that functions of D1DRs are mostly limited to the plasma membrane. Our data challenge this assumption. We show that these receptors signal from both the plasma membrane and the Golgi in the midbrain neurons relevant to locomotor and motivational effects regulated by dopamine. We have found that signaling from each compartment has distinct effects on the molecular and cellular consequences of D1DR activation. Importantly, we have found that D1DR signaling from the Golgi plays a critical role in the molecular mechanisms associated with dopaminergic signaling events related to addictive behaviors. The overall goals of this proposal are to elucidate the molecular, cellular and physiological consequences of D1DR signaling from the PM and the Golgi compartments in primary medium spiny neurons, MSNs. We have developed or adapted state-of-the-art tools such as a light-controlled nanobody recruitment system and photoactivatable bacterial adenylyl cyclase to selectively modulate D1DR signaling at a given subcellular location. We will combine these tools with molecular and cellular readouts of neuronal activity as well as a high throughput phosphoproteomics approaches to identify the consequences of signaling from each compartment. We will then apply these tools in zebrafish, an established animal model to study the significance of D1DR compartmentalized signaling in regulating dopaminergic-mediated behavior. This project brings together conceptually and technically innovative approaches in cells and in intact animals as well as high throughput methods to identify downstream targets and potentially new therapeutic targets for countering the effects of mis-regulation of dopaminergic signaling.