Oligomerization-induced Conformational Change in the C-terminal Region of NELL1 Is Necessary for the Efficient Mediation of Murine MC3T3-E1 Cell Adhesion and Spreading [Cell Biology]

February 21st, 2014 by Nakamura, Y., Hasebe, A., Takahashi, K., Iijima, M., Yoshimoto, N., Maturana, A. D., Ting, K., Kuroda, S., Niimi, T.

NELL1 is a large oligomeric secretory glycoprotein that functions as an osteoinductive factor. NELL1 contains several conserved domains, has structural similarities to thrombospondin-1, and supports osteoblastic cell adhesion through integrins. To define the structural requirements for NELL1-mediated cell adhesion, we prepared a series of recombinant NELL1 proteins (intact, deleted, and cysteine mutant) from a mammalian expression system and tested their activities. Deletion analysis demonstrated that the C-terminal cysteine-rich region of NELL1 is critical for cell adhesion activity of NELL1. Reducing agent treatment decreased the cell adhesion activity of full-length NELL1 but not of its C-terminal fragments, suggesting that the intramolecular disulfide bonds within this region are not functionally necessary, but other disulfide linkages in the N-terminal region of NELL1 may be involved in cell adhesion activity. By replacing cysteine residues with serines around the coiled-coil domain of NELL1 which is responsible for oligomerization, we created a mutant NELL1 protein that was unable to form homo-oligomers, and this monomeric mutant showed substantially lower cell adhesion activity than intact NELL1. These results suggest that an oligomerization-induced conformational change in the C-terminal region of NELL1 is important for the efficient mediation of cell adhesion and spreading by NELL1.
  • Posted in Journal of Biological Chemistry, Publications
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