The role of cell-surface receptors in the dendrite outgrowth of Drosophila motoneurons 

Interneural ContactNeural circuit assembly requires a complex coordination of developmental events. After cellular differentiation, the newly born neurons project their neurites. Our studies demonstrate that dendrites are guided to their proper target regions by cell-surface receptors whose activities are highly dynamic in time and space. Therefore, we are taking a microscopy-based approach to map the localization and activities of the signaling molecules. We are currently interested in studying Down syndrome cell adhesion molecule (Dscam) inter-neural signaling to define the site of dendrite outgrowth in the aCC motoneurons in Drosophila.

  • Kamiyama et al., Develpmental Cell (2015)
  • Furrer et al., Development (2007)


The role of Cdc42 GTPase in neural morphogenesis

ActivationDuring neuronal morphogenesis, spatial and temporal signals from multiple intracellular and extracellular sources are integrated to trigger a sequence of activities in membrane trafficking and cytoskeleton rearrangement. At the intersection of these signaling pathways, Cdc42 GTPase is particularly important. We have used the imaging tools described above together with traditional genetics to elucidate Cdc42 function in neural morphogenesis in Drosophila. These studies elucidated pathways mediating axon-guidance, dendritogenesis, and synaptogenesis within the developing CNS and dissected the role of Cdc42 in the control of cytoskeletal remodeling.

  • Sharifai et al., PloS One (2014)
  • Kamiyama et al., Science (2009)


Imaging Technologies

Methods for fluorescently labeling endogenous proteins

LibraryMany cellular processes are spatiotemporally regulated by a vast array of biological molecules. To image the localization of macromolecules, interactions between cellular proteins, and activation of signaling molecules, we have been involved in generating new fluorescence reporters based on organic dyes, fluorescent proteins, nanobodies, and FRET-based assays. We have recently developed an approach based on split fluorescent proteins that allows us to fluorescently tag endogenous proteins in mammalian cells at a large scale. The approach developed is applicable to the genome-wide analysis of gene expression, protein localization and interaction in a native cellular context. 

  • Leonetti, Sekine et al., PNAS (2016)
  • Kamiyama, Sekine et al., Nature Communicaitons (2016) 


Methods for improving the spatial resolution of optical microscopy in thick tissues

HRP StormEven with the power of effective protein labeling (e.g. using split fluorescent proteins), imaging fluorescence signals attypical sub-cellular scales (sub-100 nm) remains an obstacle: the diffraction of light limits the spatial resolution of fluorescence microscopy to severalhundred nanometers.The recent invention of Stochastic Optical Reconstruction Microscopy (STORM) has generated substantial excitement in the biological research community because it has improved the spatial resolution of optical microscopy by an order of magnitude (to ~20nm), approaching the size of a protein. In collaboration with physicists, we have helped to develop the STORM and structured illumination microscopy techniques. We are currently focused on obtaining better super-resolution imaging in thick tissue samples.

  • Li et al., Photonics Research (2017)
  • Kamiyama et al., Developmental Cell (2012)