Marc Hammarlund PhD

Assistant Professor of Genetics

Research Interests

Axon regeneration and degeneration; Neuronal plasticity; Femtosecond laser surgery; C. elegans neurobiology

Current Projects

Research Summary

Toward an immortal brain:

Individual neurons sometimes continue working for the life of the animal. In other cases, their function is abrogated by injury, disease, or age-associated decline. Since damaged or dead neurons generally cannot be replaced, the continuing function of our nervous system depends on the ability of our individual neurons to survive for as long as we do: repairing damage, resisting disease, and maintaining function over the long term. Neurons are complex cells with an extended and fragile morphology. Each neuron must generate and maintain delicate balances in membrane potential, trafficking, and secretion to perform its function. How do neurons sometimes survive and continue to function for decades, and why do they sometimes fail?

We study the cell-biological mechanisms that modulate neuronal endurance. We use the model organism C. elegans, which allows us to analyze neuronal structure and function in adult animals, in vivo, with single-neuron resolution--an approach that is difficult in other systems. We develop novel molecular and genetic tools, which we use together with single-neuron laser axotomy, in vivo imaging, optogenetics, electron microscopy, and genetic analysis, to address two fundamental questions:

1) How do neurons maintain their structure and their ability to transmit information?
2) How do neurons repair themselves when they are damaged?

Answering these questions will provide fundamental insights into the mechanisms that attempt to maintain neuronal cellular and circuit function over time: when successful, allowing the brain to outlast the body; when unsuccessful, increasing susceptibility to cognitive decline and neurological disease. By understanding and manipulating these mechanisms we aim to prevent the decline of the nervous system, resulting in its immortality.

Selected Publications

  • Hammarlund, M. and Jin, Yishi. (2014). Axon regeneration in C. elegans. Current Opinion in Neurobiology 27, 199-207.
  • Byrne, A. B., Walradt, T., Gardner, K. E., Hubbert, A., Reinke, V., and Hammarlund, M. (2014). Insulin/IGF1 Signaling Inhibits Age-Dependent Axon Regeneration. Neuron 81, 1-13.
  • Firnhaber, C. and Hammarlund, M. (2013). Neuron-specific feeding RNAi in C. elegans, and its use in a screen for essential genes required for GABA neuron function. PLoS Genetics 9(11): e1003921.
  • Williams, D. C., El Bejjani, R., Ramirez, P. M., Coakley, S., Kim, S., Lee, H., Wen, Q., Samuel, A., Lu, H., Hilliard, M. A., and Hammarlund, M. (2013). Rapid and permanent neuronal inactivation in vivo via subcellular generation of reactive oxygen using KillerRed. Cell Reports 5, 553-63.
  • El Bejjani, R. and Hammarlund, M. (2012). Notch signaling inhibits axon regeneration. Neuron 73, 268-278.
  • Hammarlund, M., Nix, P., Hauth, L., Jorgensen, E. M., and Bastiani, M. J. (2009) Axon Regeneration Requires A Conserved MAP Kinase Pathway. Science 323, 802-806.

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