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NOTE: DUE TO A CYBER ATTACK OUR UNIVERSITY WEB SYSTEM IS SHUT DOWN - TALK WILL BE RESCHEDULED
The size and structure of the dendritic arbor play important roles in determining how synaptic inputs of neurons are converted to action potential output and how neurons are integrated in the surrounding neuronal network. Accordingly, neurons with aberrant morphology have been associated with neurological disorders. Dysmorphic, enlarged neurons are, for example, a hallmark of focal epileptogenic lesions like focal cortical dysplasia (FCDIIb) and gangliogliomas (GG). However, the regulatory mechanisms governing the development of dendrites are insufficiently understood. The evolutionary conserved Ste20/Hippo kinase pathway has been proposed to play an important role in regulating the formation and maintenance of dendritic architecture. A key element of this pathway, Ste20-like kinase (SLK), regulates cytoskeletal dynamics in non-neuronal cells and is strongly expressed throughout neuronal development. Nevertheless, its function in neurons is unknown. We found that during development of mouse cortical neurons, SLK has a surprisingly specific role for proper elaboration of higher, ≥ 3rd, order dendrites both in cultured neurons and living mice. Moreover, SLK is required to maintain excitation-inhibition balance. Specifically, SLK knockdown causes a selective loss of inhibitory synapses and functional inhibition after postnatal day 15, while excitatory neurotransmission is unaffected. This mechanism may be relevant for human disease, as dysmorphic neurons within human cortical malformations exhibit significant loss of SLK expression. To uncover the signaling cascades underlying the action of SLK, we combined phosphoproteomics, protein interaction screens and single cell RNA seq. Overall, our data identifies SLK as a key regulator of both dendritic complexity during development and of inhibitory synapse maintenance.
Emerging therapeutic targets for migraine
Migraine is the third most prevalent disease worldwide and is estimated to affect upwards of 14% of the population. Our lab has used novel preclinical models to identify the delta opioid receptor (DOR) as a therapeutic target for multiple headache disorders, including migraine. We have also investigated the relationship between DOR with the pro-migraine peptide, CGRP. There is regional variation between the co-expression of DOR with CGRP or its receptor in the trigeminal complex. This work indicates that DOR agonists can moderate both CGRP release and signaling, thus regulating pro-migraine effects at two different levels. Recent work in our lab has also explored how cytoarchitectural changes in pain processing regions are critical for the maintenance of the chronic migraine state. We show that there is decreased neuronal complexity in two different models of migraine, and that restoration of tubulin dynamics, directly by HDAC6 inhibitor or indirectly by CGRP receptor antagonist, can inhibit migraine-associated symptoms. These studies provide fundamental information on how cytoskeletal dynamics are altered in chronic migraine, and form the basis for the development of HDAC6 inhibitors for headache treatment.
“Cell Surface Topography: The Role of Protein Size at Cell-Cell Interfaces”
Membrane interfaces formed at junctions between cells are often associated with characteristic patterns of membrane protein organization, such as in epithelial tissues and between cells of the immune system. While this organization can be influenced by receptor clustering, lipid domain formation, and cytoskeletal dynamics, this talk will describe how cell surface molecular height can directly contribute to the spatial arrangement of membrane proteins and downstream signaling. Using a new optical method for characterizing molecular height, together with experiments using giant vesicles in vitro systems and live immune cells, we are investigating how cell surface molecular heights can be key contributors to cell-cell communication.