How genetically engineered systems are helping to define, and in some cases redefine, the neurobiological basis of sleep and wake

Abstract

The advent of genetically engineered systems, including transgenic animals and recombinant viral vectors, has facilitated a more detailed understanding of the molecular and cellular substrates regulating brain function. In this review we highlight some of the most recent molecular biology and genetic technologies in the experimental “systems neurosciences,” many of which are rapidly becoming a methodological standard, and focus in particular on those tools and techniques that permit the reversible and cell-type specific manipulation of neurons in behaving animals. These newer techniques encompass a wide range of approaches including conditional deletion of genes based on Cre/loxP technology, gene silencing using RNA interference, cell-type specific mapping or ablation and reversible manipulation (silencing and activation) of neurons in vivo. Combining these approaches with viral vector delivery systems, in particular adeno-associated viruses (AAV), has extended, in some instances greatly, the utility of these tools. For example, the spatially- and/or temporally-restricted transduction of specific neuronal cell populations is now routinely achieved using the combination of Cre-driver mice and stereotaxic-based delivery of AAV expressing Cre-dependent cassettes. We predict that the experimental application of these tools, including creative combinatorial approaches and the development of even newer reagents, will prove necessary for a complete understanding of the neuronal circuits subserving most neurobiological functions, including the regulation of sleep and wake.

Keywords:

• adeno-associated virus
• optogenetics
• DREADD
• RNA interference
• sleep-wake regulation

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

About the Authors

Patrick M Fuller is a principal investigator at Harvard Medical School and Beth Israel Deaconess Medical Center. The investigative focus of his laboratory is the cellular and synaptic basis by which the brain regulates sleep and wakeful consciousness. His experiments seek to link the activity of defined sets of neurons with neurobehavioral and electroencephalographic outcomes in behaving animals.

Akihiro Yamanaka is a principle investigator at the Research Institute of Environmental Medicine at Nagoya University. His experimental work has focused on orexin/hypocretin neurons since the peptide was first discovered in 1998. Using slice patch-clamp recording and optogenetics, his laboratory generated key insights into the regulation of sleep/wakefulness.

Michael Lazarus is a principal investigator at the International Institute for Integrative Sleep Medicine at the University of Tsukuba. He has made key contributions to our understanding of how prostaglandin and adenosine receptors in the brain regulate body temperature and sleep. His laboratory uses innovative genetically engineered systems to investigate homeodynamics in sleep and body temperature.

Funding

This work was supported by Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (B) 24300129 (to M.L.) and 23300142 (to A.Y.); World Premier International Research Center Initiative (WPI) from the Ministry of Education, Culture, Sports, Science, and Technology (to M.L.); the National Institutes of Health (NS26837 to P.M.F.); and a grant from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan (Grant-in-Aid for Scientific Research on Innovative Areas “Mesoscopic Neurocircuitry”, 23115103, to A.Y.).