4. Developing genetic tools to probe neural circuit assembly and organization
We have a continued interest in creating tools to probe neural circuit assembly and organization. For example, the MARCM (mosaic analysis with a repressible cell marker) method in flies and MADM (mosaic analysis with double markers) method in mice allow the visualization and genetic manipulation of isolated single neurons (see Fig. 1 in Section 1 and Fig. 4 in Section 2). The Q system expanded binary expression tools. We have also generated other tools that are widely used by the research community, such as Cre reporter mTmG and integrase-mediated transgenesis for producing single-copy transgene in predetermined locus in the mouse. |
Recently, we developed TRIO (tracing the relationship between input and output) and cTRIO (cell-type-specific TRIO), which allow rabies virus-based input tracing to neurons restricted by projection, or by cell type and projection. The TRAP (targeted recombination in active population) method enables genetic access of neurons on the basis of their activity (Fig. 6), which in combination with tools for labeling, tracing, recording, and manipulating neurons, offers a powerful approach for understanding how neural circuits process information and generate behavior.
|Fig. 6: TRAPing thirst neurons. tdTomato-labeled cells in median preoptic nucleus (MnPO) after TRAPing in mice that were water-satiated (left) or water restricted (right). A specific subset of MnPO neurons became highly activated in thirsty mice. a.c., anterior commissure. Genetic access to these dehydration-activated cells allowed us to investigate their physiological properties and behavioral functions. For details, see Allen WE, DeNardo LA, Chen MZ et al. (2017) Science 357:1149-1155.
Lee, T., and Luo, L. (1999). Mosaic analysis with a repressible cell marker for studies of gene function in neuronal morphogenesis. Neuron 22, 451-461.
Zong H, Espinosa JS, Su HH, Muzumdar MD & Luo L (2005) Mosaic analysis with double markers in mice. Cell 121:479-492.
Muzumdar MD, Tasic B, Miyamichi K, Li L & Luo L (2007) A global double-fluorescent Cre reporter mouse. Genesis 45:593-605.
Potter CJ, Tasic B, Russler EV, Liang L & Luo L (2010) The Q system: a repressible binary system for transgene expression, lineage tracing and mosaic analysis. Cell 141:536-548.
Tasic B, Hippenmeyer S, Wang C, Gamboa M, Zong H, Chen-Tsai Y & Luo L (2011) Site-specific integrase-mediated transgenesis in mice via pronuclear injection. Proc Natl Acad Sci USA 108:7902-7907.
Guenthner CJ, Miyamichi K, Yang HH, Heller HC & Luo L (2013) Permanent genetic access to transiently active neurons via TRAP: targeted recombination in active populations. Neuron 78:773-84.
Schwarz LA*, Miyamichi K*, Gao XJ, Beier KT, Weissbourd B, DeLoach KE, Ren J, Ibanes S, Malenka RC, Kremer EJ & Luo L (2015). Viral-genetic tracing of the input-output organization of a central noradrenaline circuit. Nature 524:88-92.
Allen WE*, DeNardo LA*, Chen MZ*, Liu CD, Loh KM, Fenno LE, Ramakrishnan C, Deisseroth K & Luo L (2017) Thirst-associated median preoptic neurons encode an aversive motivational drive. Science 357:1149-1155.
* co-first authors
See publications for complete list and PDFs.