Office of the Chief

Section on Cellular Biophotonics

Section on Model Synaptic Systems

Section on Transmitter Signaling
 

The Section on Cellular Biophotonics studies how protein complexes are formed and maintained in living cells, and how these complexes regulate cellular functions. In particular, the Section is interested in the way that protein complexes regulate synaptic function by responding to an influx of calcium ions. The Section is currently engaged in three projects. The first involves the construction of a microscope that can be used to study protein complexes in living cells by measuring time resolved fluorescence anisotropy and fluctuations in fluorescence. The second project monitors changes in the multimeric structure of Cam kinase-II, an abundant synaptic enzyme that plays a critical role in learning, memory and heart disease. Results from this work suggest that anisotropy imaging can be used to detect structural changes in CaM kinase-II, and the Section is currently examining the activation of this protein complex in living zebrafish hearts. The third project examines the function of dysferlin, a calcium binding protein implicated in two forms of muscular dystrophy. This work has suggested that anti-sense mopholinos against dysferlin inhibit the secretion of ATP in response to plasma membrane wounding.

The Section on Model Synaptic Systems uses genetically marked neural proteins in Zebrafish to clarify the basic principles of synapse function. The Section’s work is divided into two areas: the neuromuscular junction and the effects of ethanol on neural networks in the central nervous system. Work on the neuromuscular junction involves two lines of mutant Zebrafish: one lacks acetylcholine receptors (AChRs) and the other possesses a dysfunctional rapsyn gene. Working with these mutants, the Section has determined that AChR actively directs rapsyn molecules to the synapse and that rapsyn mutants show a marked attenuation in the amplitude of AChR when motor neurons fire repeatedly. The Section is also conducting research on zebrafish embryos grown in ethanol solutions to investigate neurobiological mechanisms of fetal alcohol syndrome.

The Section on Transmitter Signaling considers the way G-protein coupled receptors modulate voltage-gated Ca2+ channels in neuronal systems. The Section’s work focuses on the creation of systems for studying these mechanisms. For example, the Section has created a model system for rapid, target-directed proteolysis in mammalian cells. This system, which includes an inducible protease and a substrate recognition sequence from the tobacco etch virus, has been demonstrated to completely cleave the targeted substrate. A second model system provides a platform for candidate molecules that facilitate the transport of endocannabinoids (eCBs) across the plasma membrane. This system uses isolated rat sympathetic neurons, which have been modified to express four components required for eCB production and detection. A third model system provides a platform for expressing heterologous proteins in adult mammalian neurons by using in vitro-transcribed mRNA and a cationic lipid transfection reagent. A fourth model system uses Rohon-Beard primary sensory neurons from Zebrafish to identify how G-protein coupled receptors modulate Ca2+ channels and contribute to mechnosensory function.