Research in the Koleske Lab

We aim to understand synapse development and how it becomes disrupted in neurodevelopmental and psychiatric 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 whole exome sequencing of patients to study genes that cause neurodevelopmental and psychiatric disorders such as autism and schizophrenia. We are using our understanding of the biochemical mechanisms affected by these mutations to develop drugs to treat these disorders. Any of the topics listed below are fertile areas for rotation projects.

Recent advances from scientists in the Koleske Lab (by project):

1)     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. We identified an enrichment of de novo mutations in the gene encoding the 330-kDa triple functional domain (TRIO) protein associated with these disorders.  TRIO contains two guanine nucleotide exchange factor (GEF) domains with distinct specificities. We discovered that genetic damage to both TGEF domains alters catalytic activity of these GEF domains.  For example, our most recent work indicates that some autism related TRIO variants increase TGEF1 activity by relieved an autoinhibition screen. In ongoing collaboration with the labs of Jess Cardin and Mike Higley, we have created mice with human TRIO mutations and are using them to understand how these mutations impact biochemical signaling, synapse development, circuit function, and behavior.

See our papers in:

o   https://news.yale.edu/2019/03/05/single-gene-linked-host-abnormalities-during-neurodevelopment

o   https://medicalxpress.com/news/2019-03-gene-linked-host-abnormalities-neurodevelopment.html

o   https://epilepsyu.com/single-gene-linked-to-host-of-abnormalities-during-neurodevelopment/

2)     Synapse stability requires a stable pool of synaptic actin.

Dendritic spines serve as receptive postsynaptic compartments on excitatory neurons and defects in their formation, density, and shape are hallmarks of many brain disorders. Spine shape and stability are principally supported by a filamentous actin network, which also organizes scaffolding proteins and neurotransmitter receptors at the postsynaptic densit. Dendritic spines contain two kinetically distinct pools of actin. The more abundant, highly dynamic pool regulates spine shape, size, and plasticity. The function of the smaller, stable actin network is not well understood, as tools to study it have not been available. In previous work, we had demonstrated that the Abl2 nonreceptor kinase and its binding partner cortactin can synergize to stabilize actin filaments in vitro.   Recently, we used FRAP of GFP-actin in single spines to demonstrate that Abl2 and cortactin are essential to maintain the stable pool in spines. Depletion of the stable actin pool via disruption of Abl2 or cortactin, or interactions between the proteins, significantly reduced spine and synapse stability. We also found that increased synaptic activity promote spine stability via enrichment of cortactin in spines, suggesting that synaptic activity acts on the stable actin pool to stabilize dendritic spines. 

See our papers in:

3)     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. Our ongoing work is exploring an unexpected finding that actin binds directly to the cytoplasmic tail of the NMDA receptor GluN2B subunit.

See our papers in:

4)     Control of MT elongation by tyrosine kinase Abl2.

Abl family kinases are essential regulators of cell shape and movement. Genetic studies revealed functional interactions between Abl kinases and microtubules, but the mechanism by which Abl family kinases regulate microtubules (MTs) remains unclear. Here, we report that Abl2 directly binds to MTs and regulates MT behaviors. Abl2 uses it C-terminal half to bind MTs, mediated in part through electrostatic binding to tubulin C-terminal tails. Using purified proteins, we found that Abl2 stably binds the MT lattice and promotes MT polymerization and stability. In cells, knockout of Abl2 significantly impairs MT growth and this defect can be rescued via re-expression of Abl2 or an Abl2 fragment containing MT-binding regions. These results show Abl2 uses its C-terminus to bind MTs and directly regulate MT dynamics.

See our most recent paper in: https://rupress.org/JCB/article/218/12/3986/132520/Regulation-of-MT-dynamics-via-direct-binding-of-an