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Updated: Jul 13, 2026
10:40
Assessment of Dictyostelium discoideum Response to Acute Mechanical Stimulation
Published on: November 9, 2017
G protein-independent Ras/PI3K/F-actin circuit regulates basic cell motility
Atsuo T Sasaki1, Chris Janetopoulos, Susan Lee
1Section of Cell and Developmental Biology, Division of Biological Sciences, and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093, USA.
The Journal of Cell Biology
|July 20, 2007
Summary
Dictyostelium cells exhibit autonomous phosphoinositide 3-kinase (PI3K) and Ras activation, forming a positive feedback circuit. This circuit drives actin dynamics, cell migration, and cytokinesis even without external signals.
Area of Science:
- Cell Biology
- Biochemistry
Background:
- Phosphoinositide 3-kinase (PI3K) activation is typically mediated by G protein-coupled receptors via Gbetagamma and Ras.
- The precise roles of Gbetagamma and Ras in PI3K activation and the dynamics of PI3K signaling without external stimuli are not fully understood.
Purpose of the Study:
- To investigate the mechanistic roles of Gbetagamma and Ras in PI3K activation.
- To explore the dynamics and function of PI3K activation in the absence of extracellular stimuli.
Main Methods:
- Utilized gbeta null cells to study PI3K and Ras activation.
- Employed simultaneous imaging analysis to observe PI3K and Ras activation dynamics.
- Investigated the interaction between PI3K and Ras-guanosine triphosphate.
Main Results:
- gbeta null cells showed PI3K and Ras activation, with reciprocal PI3K and PTEN localization, leading to PI(3,4,5)P(3) accumulation.
- Autonomous PI3K and Ras activation occurred concurrently with F-actin projections in unstimulated cells.
- A positive feedback loop between PI3K and Ras was identified, crucial for autonomous activation.
Conclusions:
- PI3K and Ras form a positive feedback circuit that drives autonomous signaling and F-actin dynamics.
- This feedback circuit is implicated in random cell migration and cytokinesis.
- The circuit may have evolved to regulate stochastic cytoskeletal changes.
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