(E-176) Left-right positioning of organelles influences chirality in micropatterned myoblast cells

Introduction:: Cell chirality is crucial for the chiral morphogenesis of tissues, yet its underlying mechanism remains unclear. Polarization of cell organelles along apical-basal, front-rear, and left-right axes has been observed to influence the orientation, rotation, and migration of cells [1-2]. Of these axes, the left-right bias of cells is particularly crucial in determining the chiral directionality of these behaviors [3-4]. Mouse myoblast cells (C2C12) cells exhibit strong counterclockwise chirality on a ring-shaped micropattern under control conditions [5]. Cells polarized their front centrosomes towards the boundary of the micropatterns and turns into a counterclockwise migration [2].

Materials and Methods:: In this study, we measured the cell chirality of mouse myoblast cells (C2C12 cells) and the placement of cell organelles using a micropatterning technique, fluorescent microscopy. The absolute and relative positioning of cell organelles (e.g. nucleus, centrosome, Golgi apparatus, mitochondria, lysosomal vesicles, actin, and tubulin filaments) on a “T” shaped micropattern was investigated using programming-based image analysis.

Results, Conclusions, and Discussions:: We found that the C2C12 cell on a "T" shaped micropattern naturally stretched into a triangular shape, with its nucleus-centrosome axis oriented towards the top-right direction of the "T". Moreover, the Golgi apparatus, lysosome, actin filaments, and microtubules were polarized on the left side of this axis, indicating a significant potential for leftward cell migration. These organelle positions were consistent with the observation of nucleus-centrosome polarization and counterclockwise migration of C2C12 cells at the boundary of the ring-shaped micropattern. Our study sheds light on the relationship between cell chirality and the left-right positioning of cell organelles.

Acknowledgements (Optional): : We thank Dr. Leo Q. Wan for providing the C2C12 cell lines. This study is supported by the Startup Grant (No. U070862) from the Department of Natural Sciences, the Research Initiation & Development Grant (No. U075874) from the Office of Research, and the College of Arts, Sciences, and Letters (CASL) Research Funding Program, University of Michigan-Dearborn.

References (Optional): : 1. Ridley, A.J., Schwartz, M.A., Burridge, K., Firtel, R.A., Ginsberg, M.H., Borisy, G., Parsons, J.T., and Horwitz, A.R. (2003). Cell migration: integrating signals from front to back. Science 302, 1704–1709.
2. Bornens, M. (2008). Organelle positioning and cell polarity. Nat. Rev. Mol. Cell Biol. 9, 874–886.
3. Xu, J., Van Keymeulen, A., Wakida, N.M., Carlton, P., Berns, M.W., and Bourne, H.R. (2007). Polarity reveals intrinsic cell chirality. Proc. Natl. Acad. Sci. U. S. A. 104, 9296–9300.
4. Fan, J., Zhang, H., Rahman, T., Stanton, D.N., and Wan, L.Q. (2019). Cell organelle-based analysis of cell chirality. Commun. Integr. Biol. 12, 78–81.
5. Wan, L.Q., Ronaldson, K., Park, M., Taylor, G., Zhang, Y., Gimble, J.M., and Vunjak-Novakovic, G. (2011). Micropatterned mammalian cells exhibit phenotype-specific left-right asymmetry. Proc. Natl. Acad. Sci. U. S. A. 108, 12295–12300.