Current projects

 
 
Electrical synapse scaffold - the key to structure/function

Electrical synapse scaffold - the key to structure/function

Electrical synapse scaffold function

Electrical synapses are often viewed as ‘simply’ the gap junction (GJ) channels that allow for ionic communication between neurons. We have found that the scaffold protein ZO1 (also called Tjp1) is required for the structure and function of the electrical synapses. The work of Audrey Marsh, the lab’s first member, and Abbey Lasseigne, a NIGMS predoctoral fellow, has ‘flipped the script’ on electrical synapses and we have an RO1 funded project from NINDS examining the molecular mechanisms by which this scaffold builds these structures. We are interested in several related areas - a short and very incomplete list:

  • Does ZO1 phase separate at the synapse? Is this a mechanisms to concentrate GJs?

  • How does ZO1 control the cell biological localization of the GJ in neurons?

  • Can ZO1 localize molecules that modify synaptic and GJ function?

  • What other molecules work with ZO1 to build electrical synapses?

 
Electrical synapses beyond the gap

Electrical synapses beyond the gap

Electrical synapse proteome

While chemical synapses are well known for their molecular complexity, the details of the proteins found at electrical synapses are not well understood. We are exploring the molecular complexity of these structures using proteomics. We are combining precise genome engineering and proximity labeling of proteins near the electrical synapse to identify the protein interaction network of electrical synapse. Jen Michel, a postdoctoral fellow in lab, leads this R21 funded project from NINDS we expect to find proteins in a number of categories:

  • Trafficking pathways controlling electrical synapse component delivery.

  • Scaffolds and other structural molecules, beyond ZO1.

  • Modulatory proteins that will affect synaptic function.

  • Cell adhesion molecules that specify electrical synapse construction.

 
Electrical and chemical synapses molecular coordination

Electrical and chemical synapses molecular coordination

Electrical and chemical synapse coordination

Neural circuits are built from electrical and chemical synapses, which each imparting their own unique properties to computation. The big question is how the nervous system chooses and then builds these different types of connections. Given their very different biochemical nature, you might think they are treated independently. Anne Martin, a Postdoctoral Fellow working in the group, is focused on a very cool protein called Neurobeachin which appears to be a master regulator of both types of synapses. Her F32 fellowship from NICHD is focused on:

  • Identifying the temporal and spatial mechanisms used by Neurobeachin to coordinate synapses.

  • Identifying Neurobeachin’s molecular synaptic coordination mechanisms.

  • Identifying other molecules that play roles in the coordination.

 
The first GJs - what proteins make them and what do they do?

The first GJs - what proteins make them and what do they do?

Gap junctions as pioneers in development

Gap junctions (GJs) are ubiquitous in animal tissues, allowing exchange of ions and small molecules. They are critical for adult homeostasis, but we are particularly intrigued by their roles early in development. Rachel Lukowicz, a NIGMS Doctoral Fellow working in the group, is working to understand how GJs contribute to early neural circuit and muscle coordination. We know the early developing nervous system and musculature extensively use GJs, but we do not know their identity, function, or how they create a functional system that can generate behavior. Rachel is exploring:

  • The molecular identity of the pioneer GJ molecules of the nervous system.

  • The molecular identity of the pioneer GJ molecules of the musculature.

  • How these early GJs in these tissue coordinate development.

 
Finding all the electrical synapses in the zebrafish brain

Finding all the electrical synapses in the zebrafish brain

Mapping the electrical connections of the brain

To understand neural circuit function, we need to know the wiring diagram of the brain. While this in and of itself is not sufficient, it grounds our understanding of the network motifs and architectures. A major gap in the field (pun intended) is that wiring diagrams tend to miss the electrical synapses. The two notable exceptions are in C. elegans and a partial rabbit retina - in both cases, 20-25% of synapses are electrical - yet, we do not understand this for a complex whole brain. In this Brain Initiative NIMH grant we seek to develop tools that will allow the community to map and investigate electrical synapses in the zebrafish brain. We will explore:

  • Cell types and distributions throughout the brain.

  • Subcellular localization of electrical synapses.

  • Plasticity and Ca dynamics of electrical synapses.

 
An atlas of zebrafish one cell and RNA profile at a time

An atlas of zebrafish one cell and RNA profile at a time

Single cell RNA-seq atlas of zebrafish

In an effort to understand neural and synaptic diversity in zebrafish, we dove into examining single cell RNA-seq. Our efforts led us to team up with John Postlethwait, Chuck Kimmel, and Monte Westerfield to develop an atlas of the entire developing zebrafish, of juvenile animals, and of adult organs. Dylan Farnsworth, and postdoctoral fellow in lab, is driving the project with an eye to ensuring it is accessible, useable, and an excellent resource for the entire community. Our main goals are:

  • Use scRNAseq on whole animals through late larval and mid-juvenile stages.

  • Use scRNAseq on the major organs of adults.

  • Develop bioinformatic tools to interrogate that data.

  • Provide all data to the community via ZFIN.