Organ systems are composed of a wealth of cellular subpopulations whose spatial organization
within a given tissue are deeply intertwined with their functions and homeostasis controls.
Similarly, within the space of a single-cell, the biochemical environment is also heterogeneous
where the dynamic interactions of molecules determine the fitness, behavior and fate of the cell.
Our understanding of the cell interactions and the biomolecule interactions has recently been
transformed by the revolutionary single-cell genomics and single-molecule imaging technologies.
However, the development and application of these technologies have been exclusively centered
on the context of mononuclear cellularity. Hiding in the blind spot are multinucleated cell-types,
including myofibers, cardiomyocytes, syncytiotrophoblasts, certain cancer cells, all of which
cause devasting human disease when go awry. The syncytial nature of the multinucleated cells,
which possess the polyploidy and often the vast cytosolic volumes, raises fascinating questions
with respect to the spatial organizations of the cell-cell interactions and biomolecule distributions.
The fundamental yet largely unknown questions include: 1) How heterogeneous is the tissue
microenvironment that surrounds the syncytial cells? 2) Do nuclei from the shared cell body
coordinate gene expression in response to the external stimuli and cell-cell communications? 3)
What is the mechanism that governs the transports and localizations of mRNAs in the
multinucleated cells? Our research program exploits the unique features of specialized cell-types
as a means to understand mechanistic underpinnings of various developmental systems. This
proposal leverages myofiber as the uniquely-suited model to investigate the above questions in
a spatially defined manner. First, we will develop and deploy new methodologies to probe the
spatial transcriptomics for the multiple types of syncytial tissues. Second, we will devise the
reverse engineering strategy to assemble the single-syncytium of human muscle with genetic
trackabilities and later graft them to live animals for the in vivo study of the cell-cell communication
and intra-syncytium mRNA distributions. Third, we will conduct the in-depth gene function and
mechanism studies to unveil new paradigms of intercellular communication and the intracellular
mRNA trafficking. Broadly, this research program relies on our diverse expertise in genomics, cell
engineering and computation such that we can create a virtuous cycle of innovation and discovery
over the course of the MIRA award. We anticipate that the knowledge and techniques will benefit
the greater biological community, including genetics, cell biologists and developmental biologists.