The N-terminal Ac-EEED sequence plays a role in alpha-smooth-muscle actin incorporation into stress fibers.
We have previously shown that the N-terminal sequence AcEEED of alpha-smooth-muscle actin causes the loss of alpha-smooth-muscle actin from stress fibers and a decrease in cell contractility when introduced in myofibroblasts as a cell-penetrating fusion peptide. Here, we have investigated the function of this sequence on stress fiber organization in living cells, using enhanced green fluorescent protein (EGFP)-tagged alpha-smooth-muscle actin. The fusion peptide provokes the gradual disappearance of EGFP fluorescence of alpha-smooth-muscle actin from stress fibers and the formation of hitherto unknown rod-like structures. In addition to alpha-smooth-muscle actin, these structures contain cytoplasmic actins, gelsolin and cofilin but not other major actin-binding proteins. These rod-like structures are also visible in wild-type fibroblasts during normal cell spreading, suggesting that they represent a physiological step in the organization of alpha-smooth-muscle actin in stress fibers. Fluorescence-recovery-after-photobleaching experiments suggest that the fusion peptide reduces the dynamics of alpha-smooth-muscle actin and its incorporation in stress fibers. Here, we propose a new mechanism of how alpha-smooth-muscle actin is incorporated in stress fibers involving the sequence Ac-EEED.
Clément
Sophie
S
Department of Pathology and Immunology, CMU, Geneva, Switzerland.
Hinz
Boris
B
Dugina
Vera
V
Gabbiani
Giulio
G
Chaponnier
Christine
C
D000199:Actins / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D036681:Fluorescence Recovery After Photobleaching; D049452:Green Fluorescent Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology / Q000502:physiology*; D010446:Peptide Fragments / Q000494:pharmacology; D011485:Protein Binding; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D022502:Stress Fibers / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D013997:Time Factors
D000199:Actins; D009842:Oligopeptides; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins