DCB Seminar Series: Dr. Vini Duarte

Dr. Vini Duarte
Postdoc
Thompson-Peer Lab

“Short Stops and Long Shots: Dendrite Regeneration in Drosophila and Mammalian Hippocampal Neurons”

This talk will feature work from two distinct projects. One project is centered around a gene called Short Stop (shot), a cytoskeletal linker molecule that plays developmental roles in a variety of tissues including the nervous system. In neurons, shot acts an actin-microtubule crosslinker that guides microtubule growth, stabilizes the neuronal cytoskeleton, and promotes arborization of dendritic arbors. Thus, we sought to investigate whether shot plays a role in regenerating dendrites. Using Drosophila dendritic arborization neurons of the peripheral nervous system, we show that shot loss-of-function (LOF) simplifies complex, more plastic dendritic arbors but can also lead to aberrant growth in stable dendritic arbors from a distinct cell type. In both cell types, shot LOF impaired dendrite regrowth after full removal using a two-photon laser. Expression of a full-length, GFP-tagged shot transgene reveals localization of shot in regenerating dendrites. We further dissect which domains of shot are essential for its localization in regenerating dendrites. This work suggests shot may be a critical regulator of dendritic maintenance and regrowth. 

The second project seeks to establish a framework by which to investigate dendrite regeneration in cultured mammalian neurons. Dendrite regeneration is a relatively novel phenomenon, with a handful of publications on Drosophila sensory neurons, C. elegans sensory neurons and Zebrafish spinal neurons. Whether dendrites can regenerate in mammalian systems remains unclear, with a string of studies in the 1980s suggesting that dendrite regeneration was rare but possible. We sought to revisit this work using rat hippocampal neurons, as drastic improvements in cell culture and microscopy may allow for more precise interrogation of dendrite regeneration in this system. We here show that mammalian neurons can survive 2-photon laser injury and regenerate in an age-dependent fashion. We hope to show that this age-dependent survival is regulated by PTEN, as has been shown for cultured primary neurons in response to glutamate-induced cytotoxic stress. Furthermore, time-lapse imaging of neurons immediately after dendrite injury reveals age-dependent morphological responses. This work provides concrete evidence that dendrites can regenerate in mammalian CNS neurons, and establishes a model by which to interrogate the biological mechanisms of mammalian dendrite regeneration.