Document Detail

FRET imaging and statistical signal processing reveal positive and negative feedback loops regulating the morphology of randomly migrating HT-1080 cells.
MedLine Citation:
PMID:  22344265     Owner:  NLM     Status:  Publisher    
Cell migration plays an important role in many physiological processes. Rho GTPases (Rac1, Cdc42, RhoA) and phosphatidyl inositols have been extensively studied in directional cell migration. However, it remains unclear how Rho GTPases and phosphatidyl inositols regulate random cell migration in space and time. Here, we attempt to address this issue by fluorescence resonance energy transfer (FRET) imaging and statistical signal processing. First, we acquired time-lapse images of random migration in HT-1080 fibrosarcoma cells expressing FRET biosensors of Rho GTPases and phosphatidyl inositols. We developed an image processing algorithm to extract FRET values and velocities at the leading edge of migrating cells. Auto- and cross-correlation analysis suggested the involvement of feedback regulations among Rac1, phosphatidyl inositols, and membrane protrusions. To verify the feedback regulations, we employed an acute inhibition of the signaling pathway with pharmaceutical inhibitors. The inhibition of actin polymerization decreased Rac1 activity, indicating the presence of positive feedback from actin polymerization to Rac1. Furthermore, treatment with PI3-kinase inhibitor induced an adaptation of Rac1 activity, i.e., a transient reduction of Rac1 activity followed by recovery to the basal level. In silico modeling that reproduced the adaptation predicted the existence of a negative feedback loop from Rac1 to actin polymerization. Finally, we identified MLCK as a convincing factor for the negative feedback. These findings quantitatively demonstrate positive and negative feedback loops that are comprised of actin, Rac1 and MLCK, and account for the ordered patterns of membrane dynamics observed in randomly migrating cells.
Katsuyuki Kunida; Michiyuki Matsuda; Kazuhiro Aoki
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-2-17
Journal Detail:
Title:  Journal of cell science     Volume:  -     ISSN:  1477-9137     ISO Abbreviation:  -     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-2-20     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0052457     Medline TA:  J Cell Sci     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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