Summary of the projects

[A01] Molecular mechanisms of flexible environmental responses using spontaneous fluctuations in cell movement

 

Principal Investigator:
Masahiro Ueda, Specially Appointed Professor, Osaka University
(Specialty: Biophysics; Role: Measurement of intracellular molecular dynamics)
Co-Investigators:
Hiroaki Takagi, Instructor, Nara Medical University
(Specialty: Biophysics; Role: Theories of cell movement and morphology)
Yuichi Togashi, Instructor, Osaka University
(Specialty: Theoretical biology; Role: Theories of self-organization)

 

Cellular slime mold produces collective movement among large numbers of cells through cross-talk between the environment and cells (i.e., the self-organized gradient field of guidance cues and chemotaxis with that field), and these cells thereby form a multicellular organism. Previous research has suggested that the movements of individual cells must fluctuate randomly to a certain extent for that collective movement to be efficient. Thus, the current research will clarify the mechanisms by which random cellular motility arises spontaneously and intrinsically based on the dynamics of intracellular reaction networks. This research will also elucidate the mechanisms of the intracellular signal transduction responsible for the directional response to the chemoattractant gradient field. These efforts will help explore the possibility that cells aptly use fluctuations in their movement in their environmental responses.

 

[A01] Mechanisms of immunodynamics through the spatiotemporal regulation of cell adhesion

 

Principal Investigator:
Tatsuo Kinashi, Professor, Kansai Medical University
(Specialty: Immunology; Role: Supervising the project)
Co-Investigators:
Tomoya Katakai, Instructor, Kansai Medical University
(Specialty: Immunology; Role: In vivo observation with a two-photon laser microscope)
Yoshihiro Ueda, Instructor, Kansai Medical University
(Specialty: Immunology ;Role: Molecular analysis of the regulation of adhesion and
(immunodynamics and imaging)
Katsutoshi Habiro, Assistant Professor, Kansai Medical University
(Specialty: Immunology ; Role: Antigen recognition and analysis of lymphocyte dynamics)

 

This research focuses on the dynamic in vivo migration of immune cells and seeks to clarify how the complex movement exhibited by individual immune cells is comprehensively regulated in the immune system, which is essentially a higher-order community of cells. First, this research will use molecular and cell imaging technology and analytical techniques to analyze mechanisms of self-organization and temporal and spatial fluctuations in molecules related to cell polarity and cell adhesion and migration in simplified systems. This research will then focus on processes in tissues and will  elucidate how cell adhesion and movement observed in simplified in vitro systems are restricted and modified by tissue environments. To that end, this research will visualize the microenvironments that form lymphoid tissues and will establish techniques of observation and manipulation in vivo, ex vivo, and via tissue slices. This research will also explore cross-talk between immune cells and their environments in vivo.

 

[A02] Mechanisms that regulate migrating cell dynamics in the developing brain
 
Principal Investigator:
Kazunori Nakajima, Professor, Keio University
(Specialty: Developmental neurobiology; Role: Supervising the project)
Co-Investigators:
Hidenori Tabata, Assistant Professor, Keio University
(Specialty: Live imaging; Role: Imaging analysis of migrating cells)
Daisuke Tanaka, Instructor, Keio University
(Specialty: Developmental neurobiology; Role: Molecular analysis of migrating cells)
Shigeaki Kanatani, Instructor, Keio University
(Specialty: Developmental neurobiology; Role: Analysis of migrating cells using culture systems)
Michihiko Aramaki, Instructor, Keio University
(Specialty: Genetics & pediatrics; Role: Analysis of the effect of microenvironments
on migrating cells)
 
This project will seek to clarify how the migration of brain cells from their sites of origin to their final destinations is regulated through interactions with the surrounding microenvironments, especially focusing on the migrating neurons in the developing mouse cerebral cortex. We would like to understand, for example, how the migratory direction, speed change during migration, and the commitment to specific migratory paths are controlled by an interplay between the migrating cell–endogenous machineries and extracellular mechanisms. We will collaborate with other teams to apply various experimental systems to the analyses of migrating brain cells.

 

 

[A02] Cross-talk between the epithelium and basement membrane during gonad formation in nematodes

 

Principal Investigator:
Kiyoji Nishiwaki, Professor, Kwansei Gakuin University
(Specialty: Developmental genetics; Role: Supervising the research)
Co-Investigator:
Shin Takagi, Associate Professor, Nagoya University
(Specialty: Neuroembryology; Role: Induction of gene expression at the cellular level using an infrared laser)

 

In the process of animal development, morphogenesis as a result of the migration of a tubular epithelium is often observed. The gonads of the nematode Caenorhabditis elegans also consist of epithelial tubes, and a pair of distal tip cells (DTCs) originate at both ends of the gonad primordium. The gonads are formed by the migration of the DTCs, which form U-shaped symmetrical arms during the larval stage. The surface of epithelial tubes has a basement membrane that physically supports epithelial sheets. As the epithelial tubes stretch and turn, the basement membrane is broken down and reorganized by the DTCs and surrounding cells, but this basement membrane conversely regulates the cytoskeleton of DTCs via receptors such as integrins. This research focuses on the cross-talk between these epithelial cells and the basement membrane. Through the functional identification and in vivo imaging of molecules acting in DTC migration and in close concert with participating researchers, we will work to clarify how the extracellular matrix regulates fluctuations in and restrictions on cell migration.

 

[A03] Neurogenesis regulated through three-dimensional cellular movement and cell-cell interactions within the neuroepithelium

 

Principal Investigator:
Takaki Miyata, Professor, Nagoya University
(Specialty: Neural development; Role: Supervising the research)
Co-Investigators:
Ayano Kawaguchi, Associate Professor, Nagoya University
(Specialty: Neural development; Role: Single-cell profiling based on gene expression analysis)
Akira Sakakibara, Assistant Professor, Nagoya University
(Specialty: Cell biology; Role: Imaging and functional experiments on cell movement)

 

The neural tube and the walls of the early embryonic brain vesicles are composed entirely of undifferentiated progenitor cells and are referred to collectively as the neuroepithelium (NE). Structurally, the NE is pseudostratified; that is, although there may be up to ten layers of nuclei, the cytoplasm of each cell extends to contact both the apical and basal surfaces of the wall, resulting in a bipolar cellular morphology up to 100 μm in length. Progenitor cells are born at the apical surface of the NE, and their nuclei move toward the basal side of the NE during G1 of the cell cycle. After completing S-phase in the basal portion of the NE, the nuclei return to the apical surface, where they undergo division as their parent cells did. Thus, the location of any given progenitor cell during this interkinetic nuclear migration (INM) reflects the age of the cell or its degree of progression through the cell cycle. In this project, we will carefully observe cells within the NE, focusing on the relationship between cells differing in age, cell cycle status, and migration direction, and will perform functional experiments to manipulate cell-cell interactions. The goal of this project is to understand the significance of INM and pseudostratification in ordered neurogenesis.

 

[A03] The role of forces and the cellular responses to them as a mechanism for epithelial morphogenesis

 

Principal Investigator:
Shigeo Hayashi, Group Director, RIKEN Center for Developmental Biology
(Specialty: Developmental biology; Role: Analysis of fluctuations in epithelial movement)
Co-Investigator:
Hisao Honda, Professor, University of Hyogo
(Specialty: Theoretical biology & biophysics; Role: Analysis and 3-D simulation of multi-cell movement)

 

This research seeks to understand the mechanical basis of cellular interactions that regulate epithelial morphogenesis. Cellular forces produce mechanical strain in the epithelium, and alleviation of that strain is essential for smooth-tissue movement. As a consequence of epithelial cells behaving as elastic bodies, their shape changes and their movement proceed with local fluctuations. The embryonic tracheal system of Drosophila melanogaster will be used to elucidate (1) the mechanisms that coordinate cell movement, (2) the mechanisms for alleviating tissue strain, and (3) the process by which cross-talk occurs between these two mechanisms. To accomplish these goals, the mechanical state of cells will be measured by combining techniques such as quantitative cell imaging at high temporal and spatial resolution, drug inhibition, and laser perturbation of subcellular structures, and the results will be used to construct epithelial cell models that will be verified by simulations and experiments.