Waxham Lab

Department of Neuroscience

McGovern Medical School

Current Research

The Challenge

Synapses are the sites of memory storage and their ability to adapt (synaptic plasticity) while maintaining stability is remarkable evolutionary design. Molecular components (proteins, lipids, organelles) have limited lifetimes, leaving a major quesiton for how information can be stably encoded at synapses long-term. Synpatic spines are a specialized structure on the post-synaptic side of the synapse (examples extending from the dendrite in the figure) that help solve this problem by providing isolated compartments for biochemical signal processing and localized adaptations to take place. In addition to investigating these basic neuronal cell biology questions, we are also studying how the system of synaptic molecules becomes unbalanced during normal aging, following brain injury or during neurodegenerative processes.

The Approach

To uncover the mechanisms underlying synaptic plasticity we use an array of state-of-the-art imaging and biophysical approaches to address the problem at the molecular and cellular level. Confocal and super-resolution fluorescence imaging and multi-photon fluorescence spectroscopy reveal the distribution and dynamics of protein or organelle movement. High-resolution cryo-electron microscopy and tomography reveal the structural details of molecules and organelles in isolation and in their native cellular environment. Together with detailed analysis of enzyme kinetics and protein-protein interactions assessed using biochemical and reconstitution approach, a comprehensive model of synaptic biology and synaptic plasticity will be attained.

Selected Publications

Mitochondria squeezed at the axon bridge between two synaptic terminals.

Fischer, T.D., Dash, P.K., Liu, J. and Waxham, M.N. (2018) Morphology of Mitochondria in Spatially Restricted Axons Revealed by Cryo-Electron Tomography. PloS Biology.

Cryo-EM reveals nanodomains in synthetic and biological membranes. The thickness of phase separated vesicles is highlighted in color. Thickness scale on the right in Angstroms.
Heberle, FA., Doktrova, M., Scott, H.L., Skinkle, A.D., Waxham, M.N., and Levental, I. (2020). Direct label-free imaging of nanodomains in biomimetic and biological membranes by cryogenic electron microscopy. Proc. Natl. Acad. Sci. USA

Electron tomography of actin/CaMKII supramolecular structures formed on lipid monolayers. Individual CaMKII molecules are identified in red circles.

Wang,Q., Chen, M., Schafer, N.P., Bueno, C. Song, S.S., Hudmon, A. Wolynes, P.G., Waxham, M.N. and Cheung, M.S. (2019) Calcium/calmodulin-dependent kinase II – Actin assemblies and their dynamic regulation by calmodulin in dendritic spines. Proc. Natl. Acad. Sci. USA.