Research in the Koleske Lab
Cytoskeletal control mechanisms that guide synapse and dendrite development and how they become disrupted in neurodevelopmental disorders.
Our lab has a long-standing interest in elucidating the mechanisms that control synapse and dendrite development and how these mechanisms become compromised in neurodevelopmental and psychiatric disorders. We use genetic tools to investigate how disruption of these key regulators impact synapse and dendrite structure and behavior in mice. We use live cell microscopy, fluorescence recovery after photobleaching (FRAP), and electrophysiology to test how these manipulations impact neuronal morphogenesis, cytoskeletal dynamics, and neurotransmission and synaptic plasticity in developing neurons. Finally, we use advanced biochemical and biophysical techniques, including single particle tracking in live cells and cryo-EM to understand the structure and function of the molecules under study. We also have a growing interest in using genomic data from whole exome sequencing of patients elucidate the cellular and biochemical mechanisms that cause neurodevelopmental and psychiatric disorders such as autism and schizophrenia. We are using our understanding of these biochemical mechanisms to develop drugs to treat these disorders.
Recent advances from scientists in the Koleske Lab:
A key trigger for synapse maturation
Synapses in the developing brain are structurally dynamic but become stable by early adulthood. INP Student Mitch Omar discovered that an extracellular matrix molecule called laminin α5 stabilizes synapses during this developmental transition and we elucidated key cellular and molecular mechanisms by which it acts. See our paper in Cell Reports.
Stabilization of actin filaments by cortactin.
The actin-binding protein cortactin promotes the formation and maintenance of actin-rich structures, including lamellipodial protrusions in fibroblasts and neuronal dendritic spines. Cortactin cellular functions have been attributed to its activation of the Arp2/3 complex, which stimulates actin branch nucleation, and to its ability to recruit regulators of Rho family GTPases. Cortactin also binds actin filaments and slows filament depolymerization, but the mechanism by which it does so, and the relationship between actin binding and stabilization, is unclear. Using a combination of in vitro biochemical assays and total internal reflection fluorescence microscopy to measure rates of single filament actin depolymerization, MSTP student Alex Scherer defined the key cortactin-actin interactions are necessary and sufficient to stabilize actin filaments. Our ongoing work is using structural methods to obtain a high-resolution perspective of the cortactin:actin complexes and using FRAP and super-resolution approaches to understand how alteration of cortactin impacts actin structure and dynamics in dendritic spines. See our papers in the Journal of Biological Chemistry (1) (2) , Science Reports, and the Journal of Neuroscience.
Mutations in Trio cause autism, schizophrenia, and related disorders.
Bipolar disorder, schizophrenia, autism, and intellectual disability are complex neurodevelopmental disorders, debilitating millions of people. Therapeutic progress is limited by poor understanding of underlying molecular pathways. Using a targeted search, we identified an enrichment of de novo mutations in the gene encoding the 330-kDa triple functional domain (TRIO) protein associated with neurodevelopmental disorders. TRIO contains two guanine nucleotide exchange factor (GEF) domains with distinct specificities. In collaboration with the Mains and Eipper groups at UConn, INP student Sara Katrancha discovered that genetic damage to both GEF domains altered TRIO catalytic activity, decreasing GEF1 activity and increasing GEF2 activity. In ongoing work, we are using CRISPR/Cas9 technology to create mice with human TRIO mutations to help us discover the mechanisms by which disruption of TRIO function impairs brain development and function. See our paper in Human Molecular Genetics, and look for our upcoming publication of the TRIO mutant model mice.
NMDA receptor dysfunction as a cause of cognitive impairment in Noonan Syndrome.
Hyperactivating mutations in the non-receptor tyrosine phosphatase SHP2 cause Noonan syndrome (NS). NS is associated with cognitive deficits, but how hyperactivation of SHP2 in NS changes neuron function was not well understood. INP student Aaron Levy found that SHP2 uncouples the NMDA receptor to from the cytoskeletal adaptor protein Nck1 and this reduces NMDA receptor transmission, synaptic plasticity, and causes learning and memory defects. Look for our upcoming paper in press at Cell Reports and the accompanying Press Releases (search on Levy, Xiao, Koleske, Noonan Syndrome).
Diversity and Inclusion
Our group is composed of individuals from diverse scientific and personal backgrounds who bring their talents, willingness to strive, and work ethic to all of our professional and social activities. We are committed to treating each other with respect, dignity, fairness, caring, equality, to help build and maintain each other’s self-esteem, and to support each other in our collective achievements.