Profilin 1 is a crucial actin regulator, interacting with monomeric actin and several actin-binding proteins controlling actin polymerization. Recently, it has become evident that this profilin isoform associates with microtubules via formins and interferes with microtubule elongation at the cell periphery. Recruitment of microtubule-associated profilin upon extensive actin polymerizations, for example, at the cell edge, enhances microtubule growth, indicating that profilin contributes to the coordination of actin and microtubule organization. Here, we provide further evidence for the profilin-microtubule connection by demonstrating that it also functions in centrosomes where it impacts on microtubule nucleation.
- MeSH
- Actins metabolism MeSH
- Caco-2 Cells MeSH
- Centrosome metabolism MeSH
- Formins metabolism MeSH
- Gene Knockout Techniques MeSH
- Humans MeSH
- Melanoma, Experimental metabolism pathology MeSH
- Microfilament Proteins metabolism MeSH
- Microtubules metabolism MeSH
- Mice MeSH
- Skin Neoplasms metabolism pathology MeSH
- Polymerization MeSH
- Profilins genetics metabolism MeSH
- Signal Transduction genetics MeSH
- Transfection MeSH
- Tubulin metabolism MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Profilin controls actin nucleation and assembly processes in eukaryotic cells. Actin nucleation and elongation promoting factors (NEPFs) such as Ena/VASP, formins, and WASP-family proteins recruit profilin:actin for filament formation. Some of these are found to be microtubule associated, making actin polymerization from microtubule-associated platforms possible. Microtubules are implicated in focal adhesion turnover, cell polarity establishment, and migration, illustrating the coupling between actin and microtubule systems. Here we demonstrate that profilin is functionally linked to microtubules with formins and point to formins as major mediators of this association. To reach this conclusion, we combined different fluorescence microscopy techniques, including superresolution microscopy, with siRNA modulation of profilin expression and drug treatments to interfere with actin dynamics. Our studies show that profilin dynamically associates with microtubules and this fraction of profilin contributes to balance actin assembly during homeostatic cell growth and affects micro-tubule dynamics. Hence profilin functions as a regulator of microtubule (+)-end turnover in addition to being an actin control element.
- MeSH
- Actins metabolism MeSH
- Cell Adhesion MeSH
- Cell Culture Techniques MeSH
- Cytoskeleton metabolism MeSH
- Fetal Proteins metabolism MeSH
- Microscopy, Fluorescence MeSH
- Focal Adhesions metabolism MeSH
- HEK293 Cells MeSH
- Nuclear Proteins metabolism MeSH
- Humans MeSH
- RNA, Small Interfering MeSH
- Melanoma, Experimental MeSH
- Actin Cytoskeleton metabolism MeSH
- Microfilament Proteins metabolism MeSH
- Microtubules metabolism MeSH
- Cell Movement physiology MeSH
- Profilins metabolism MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
BACKGROUND: 9-[2-(phosphonomethoxy)ethyl] guanine (PMEG) is a nucleotide analogue with anticancer activity. Here we investigate the role of ERK, p38, JNK and AKT kinases in PMEG-induced apoptosis. MATERIALS AND METHODS: CCRF-CEM and HL-60 leukemia cells were used to assess MAPK mRNA and protein expression in PMEG-treated cells. MAPK activation was measured using phospho-specific antibodies. Apoptosis was evaluated by caspase-3 and PARP cleavage. RESULTS: Up-regulation of p38β, γ and δ mRNA were observed following PMEG treatment of CCRF-CEM cells, however, the total protein expression remained unchanged. Neither PMEG nor its analogue 9-[2-(phosphonomethoxy) ethyl]-2,6-diaminopurine (PMEDAP) induced p38 kinase phosphorylation in CCRF-CEM cells, whereas increased p38 phosphorylation was observed in HL-60 cells. The ERK pathway was also activated by these compounds. Pretreatment of the cells with the p38 inhibitor SB203580 diminished drug-induced apoptosis whereas inhibition of ERK, JNK or AKT pathways did not. [corrected]. CONCLUSION: PMEG- and PMEDAP-induced. [corrected].
- MeSH
- Adenine analogs & derivatives pharmacology MeSH
- Enzyme Activation drug effects MeSH
- Extracellular Signal-Regulated MAP Kinases antagonists & inhibitors metabolism MeSH
- Guanine analogs & derivatives pharmacology MeSH
- HL-60 Cells MeSH
- Caspase 3 metabolism MeSH
- Humans MeSH
- MAP Kinase Kinase 4 antagonists & inhibitors metabolism MeSH
- MAP Kinase Signaling System drug effects MeSH
- RNA, Messenger biosynthesis genetics MeSH
- p38 Mitogen-Activated Protein Kinases antagonists & inhibitors biosynthesis genetics metabolism MeSH
- Mitogen-Activated Protein Kinases antagonists & inhibitors biosynthesis genetics metabolism MeSH
- Cell Line, Tumor MeSH
- Organophosphorus Compounds pharmacology MeSH
- Antineoplastic Agents pharmacology MeSH
- Proto-Oncogene Proteins c-akt antagonists & inhibitors metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
