Summary
Chemotaxis is a highly coordinated biological system where chemoattractants trigger multiple signal transduction pathways which act in concert to bring about directed migration. A signaling pathway acting through PIP3, which accumulates at the leading edge of the cell, has been extensively characterized. However, chemotaxis still remains in cells depleted of PIP3, suggesting there are PIP3-independent pathways. We have identified a pathway involving TorC2-PKBR1 as well as another containing PLA2 activity that act in parallel with PIP3. Activation of PKBR1, a myristoylated Protein Kinase B homolog, is dependent on TorC2 (Rapamycin-insensitive Tor complex 2) kinase but is completely independent of PIP3. In response to chemoattractant, PKBs rapidly phosphorylate at least eight proteins, including Talin B, PI4P 5-kinase, two RasGefs, and a RhoGap. These studies help to link the signaling pathways to specific effectors and provide a more complete understanding of chemotaxis.
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Acknowledgments
The authors wish to thank Dr. Stacey Willard for sharing unpublished data. This work was supported by NIH GM 28007 and NIH GM 34933 to P.N.D. and by the Uehara Memorial Foundation to Y.K.
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Kamimura, Y., Tang, M., Devreotes, P. (2009). Assays for Chemotaxis and Chemoattractant-Stimulated TorC2 Activation and PKB Substrate Phosphorylation in Dictyostelium . In: Jin, T., Hereld, D. (eds) Chemotaxis. Methods in Molecular Biology™, vol 571. Humana Press, Totowa, NJ. https://doi.org/10.1007/978-1-60761-198-1_17
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DOI: https://doi.org/10.1007/978-1-60761-198-1_17
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