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Profilin induces lamellipodia by growth factor independent mechanism
Author(s) -
Syriani Enrique,
GomezCabrero Azucena,
Bosch Marta,
Moya Alicia,
Abad Elena,
Gual Arcadi,
Gasull Xavier,
Morales Miguel
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.06-7654com
Subject(s) - lamellipodium , profilin , microbiology and biotechnology , actin , chemistry , pseudopodia , biology , biochemistry , cell migration , actin cytoskeleton , cytoskeleton , cell
Profilin has been implicated in cell mo tility and in a variety of cellular processes, such as membrane extension, endocytosis, and formation of focal complexes. In vivo, profilin replenish the pool of ATP‐actin monomers by increasing the rate of nucleotide exchange of ADP‐actin for ATP‐actin, promoting the incorporation of new actin monomers at the barbed end of actin filaments. For this report, we generated a membrane‐permeable version of profilin I (PTD4‐PfnI) for the alteration of intracellular profilin levels taking advantage of the protein transduction technique. We show that profilin I induces lamellipodia formation independently of growth factor presence in primary bovine trabecular meshwork (BTM) cells. The effects are time‐ and concentration‐dependent and specific to the profilin I isoform. Profilin II, the neuronal isoform, failed to extend lamellipodia in the same degree as profilin I. H133S, a mutation in the polyproline binding domain, showed a reduced ability to induce lamellipo‐ dia. H199E, mutation in the actin binding domain failed to induce membrane spreading and inhibit fetal bovine serum (FBS) ‐induced lamellipodia extension. Incubation with a synthetic polyproline domain peptide (GP5)3, fused to a transduction domain, abolished lamellipodia induction by profilin or FBS. Time‐lapse microscopy confirmed the effects of profilin on lamel‐ lipodia extension with a higher spreading velocity than FBS. PTD4‐Pfn I was found in the inner lamellipodia domain, at the membrane leading edge where it colocalizes with endogenous profilin. While FBS‐induced lamellipodia formation activates Rac1, PTD4‐Pfn I stimulation did not induce Rac1 activation. We propose a role of profilin I favoring lamellipodia formation by a mechanism downstream of growth factor.—Syriani, E., Gomez‐Cabrero, A., Bosch, M., Moya, A., Abad, E., Gual, A., Gasull, X., Morales, M. Profilin induces lamellipodia by growth factor independent mechanism. FASEB J . 22, 1581–1596 (2008)