A 130 kDa protein 4.1B regulates cell adhesion, spreading and migration of mouse embryo fibroblasts by influencing actin cytoskeleton organization [Membrane Biology]

December 31st, 2013 by Wang, J., Song, J., An, C., Dong, W., Zhang, J., Yin, C., Hale, J., Baines, A. J., Narla, M., An, X.

Protein 4.1B is a member of protein 4.1 family, adaptor proteins at the interface of membranes and the cytoskeleton. It is expressed in most mammalian tissues, and is known to be required in formation of nervous and cardiac systems; it is also a tumor suppressor with a role in metastasis. Here, we explore functions of 4.1B using primary mouse embryonic fibroblasts (MEF) derived from wild type and 4.1B knockout mice. MEF cells express two 4.1B isoforms: 130 kDa and 60 kDa. 130 kDa 4.1B was absent from 4.1B knockout MEF cells, but 60 kDa 4.1B remained, suggesting incomplete knockout. While the 130 kDa isoform was predominantly located at the plasma membrane, the 60 kDa isoform was enriched in nuclei. 130 kDa-deficient 4.1B MEF cells exhibited impaired cell adhesion, spreading and migration; they also failed to form actin stress fibers. Impaired cell spreading and stress fiber formation were rescued by re-expression of the 130 kDa 4.1B, but not the 60 kDa 4.1B. Our findings document novel, isoform-selective roles for 130 kDa 4.1B in adhesion, spreading and migration of MEF cells by affecting actin organization, giving new insight into 4.1B functions in normal tissues, as well as its role in cancer.
  • Posted in Journal of Biological Chemistry, Publications
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