PURPOSE It was recently shown that phosphatidylinositol-(PI)3 kinase is upregulated in wounded rabbit corneal epithelia. Extracellular signal-regulated kinase (erk)-1 and -2 proteins and PI-3 kinase were activated in embryonic corneal epithelia after 1-hour stimulation by type I collagen. In the current investigation specific inhibitors of PI-3 kinase and mitogen-activated kinase-kinase (MEK-1 ...

The smooth muscle (SM) alpha-actin gene activated during the early stages of embryonic cardiovascular development is switched off in late stage heart tissue and replaced by cardiac and skeletal alpha-actins. SM alpha-actin also appears during vascular development, but becomes the single most abundant protein in adult vascular smooth muscle cells. Tissue-specific expression of SM alpha-actin is ...

Actin is not only a major cytoskeletal component in all eukaryotic cells but also a nuclear protein that plays a role in gene transcription. We put together data from in vitro and in vivo experiments that begin to provide insights into the molecular mechanisms by which actin functions in transcription. Recent studies performed in vitro have suggested that actin, in direct contact with the trans...

The integration of signals received by a cell, and their transduction to targets, is essential for all cellular responses. The cytoskeleton has been identified as a major target of signalling cascades in both animal and plant cells. Self-incompatibility (SI) in Papaver rhoeas involves an allele-specific recognition between stigmatic S-proteins and pollen, resulting in the inhibition of incompat...

The actin and microtubule cytoskeletons regulate cell shape across phyla, from bacteria to metazoans. In organisms with cell walls, the wall acts as a primary constraint of shape, and generation of specific cell shape depends on cytoskeletal organization for wall deposition and/or cell expansion. In higher plants, cortical microtubules help to organize cell wall construction by positioning the ...

In order to measure the content of beta- and gamma-actin mRNA in mouse oocytes and ovulated eggs, Northern and slot blots were hybridized to complementary RNA probes transcribed from mouse isotype-specific cDNA sequences. The blots included samples of isotype-specific sense strand RNA standards prepared from the same cDNA sequences. Total actin mRNA content was estimated to be 40 fg per preovul...

Individual isoforms of the protein kinase C (PKC) family of kinases may have assumed distinct responsibilities for the control of complex and diverse cellular functions. In this study, we show that an isoform specific interaction between PKC epsilon and filamentous actin may serve as a necessary prelude to the enhancement of glutamate exocytosis from nerve terminals. Using a combination of cose...

Microtubule-associated protein 2 (MAP2) is a neuronal phosphoprotein that promotes net microtubule growth and actin cross-linking and bundling in vitro. Little is known about MAP2 regulation or its interaction with the cytoskeleton in vivo. Here we investigate the in vivo function of three specific sites of phosphorylation on MAP2. cAMP-dependent protein kinase activity disrupts the MAP2-microt...

Actin has been shown to be present in the nucleoli, kinetochore and centriolar regions, and in the mitotic spindle of rat kangaroo cells which have been stained with fluorescently labeled heavy meromyosin. The actin in the spindle is confined to the fibers that connect the chromosomes with the centriolar region. Actin was not present in astral fibers, in the continuous spindle fibers that conne...

Cadherin cell adhesion molecules are major determinants of tissue patterning which function in cooperation with the actin cytoskeleton. In the context of stable adhesion, cadherin/catenin complexes are often envisaged to passively scaffold onto cortical actin filaments. However, cadherins also form dynamic adhesive contacts during wound healing and morphogenesis. Here actin polymerization has b...