Oligomers of the ATPase EHD2 confine caveolae to the plasma membrane through association with actin

Caveolae are plasma membrane microdomains that play important roles in signalling and endocytosis. The ATPase EHD2 shuttles on and off the static population of caveolae in an ATPase cycledependent manner and links caveolae to actin filaments confining them to the plasma membrane

Effect of Cavtratin, a Caveolin-1 Scaffolding Domain Peptide, on Oligodendroglial Signaling Cascades

Caveolin and caveolin containing rafts are involved in the signaling of growth factors in various cell types. Previous reports of our lab indicated a co-localization of caveolin and the high affinity nerve growth factor (NGF) receptor tyrosine kinase A (TrkA). Mutual effects have been observed among which a caveolin-1 knock-down resulted in an impairment of the NGF signaling cascade rather than in an increase of activity as expected from other growth factor reports. On the other hand, an over-expression of caveolin-1 impaired the NGF stimulated activity of p42/44 mitogen activated protein kinases (MAPK). In this study, we used a caveolin-1 scaffolding domain (CSD) peptide (cavtratin) of which an inhibitory effect on growth factor receptors was reported. Our data showed that cavtratin suppresses the NGF-induced phosphorylation of TrkA as well as the activation of MAPK in porcine oligodendrocytes significantly

High-resolution mapping reveals topologically distinct cellular pools of phosphatidylserine

Phosphatidylserine exists lumenally in the ER, Golgi, and mitochondria but cytoplasmically in the trans-Golgi and at the plasma membrane, which suggests that functionally important flipping may occur during trafficking

MURC/Cavin-4 and cavin family members form tissue-specific caveolar complexes

Polymerase I and transcript release factor (PTRF)/Cavin is a cytoplasmic protein whose expression is obligatory for caveola formation. Using biochemistry and fluorescence resonance energy transfer–based approaches, we now show that a family of related proteins, PTRF/Cavin-1, serum deprivation response (SDR)/Cavin-2, SDR-related gene product that binds to C kinase (SRBC)/Cavin-3, and muscle-restricted coiled-coil protein (MURC)/Cavin-4, forms a multiprotein complex that associates with caveolae. This complex can constitutively assemble in the cytosol and associate with caveolin at plasma membrane caveolae. Cavin-1, but not other cavins, can induce caveola formation in a heterologous system and is required for the recruitment of the cavin complex to caveolae. The tissue-restricted expression of cavins suggests that caveolae may perform tissue-specific functions regulated by the composition of the cavin complex. Cavin-4 is expressed predominantly in muscle, and its distribution is perturbed in human muscle disease associated with Caveolin-3 dysfunction, identifying Cavin-4 as a novel muscle disease candidate caveolar protein

Seg1 controls eisosome assembly and shape

Eisosomes are stable domains at the plasma membrane of the budding yeast Saccharomyces cerevisiae and have been proposed to function in endocytosis. Eisosomes are composed of two main cytoplasmic proteins, Pil1 and Lsp1, that form a scaffold around furrow-like plasma membrane invaginations. We show here that the poorly characterized eisosome protein Seg1/Ymr086w is important for eisosome biogenesis and architecture. Seg1 was required for efficient incorporation of Pil1 into eisosomes and the generation of normal plasma membrane furrows. Seg1 preceded Pil1 during eisosome formation and established a platform for the assembly of other eisosome components. This platform was further shaped and stabilized upon the arrival of Pil1 and Lsp1. Moreover, Seg1 abundance controlled the shape of eisosomes by determining their length. Similarly, the Schizosaccharomyces pombe Seg1-like protein Sle1 was necessary to generate the filamentous eisosomes present in fission yeast. The function of Seg1 in the stepwise biogenesis of eisosomes reveals striking architectural similarities between eisosomes in yeast and caveolae in mammals

Lateral Membrane Domains Organize and Regulate Components of Signal Transduction Pathways

194 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.Components of the mitogen activated protein kinase (MAPK) signaling cascade also localized into domains in vesicles containing acidic lipids. The formation of lateral membrane domains induced by Ki-Ras 4B and the Raf-cysteine rich domain (Raf-CRD) was inhibited by the anti-tumor agent farnesylthiosalicylic acid (FTS). The inhibition of Ras membrane domains by farnesylthiosalisylic acid was proposed to inhibit Ras function and the results provided a model of how the membrane organizes and regulates the MAP kinase signaling cascade.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Lateral Membrane Domains Organize and Regulate Components of Signal Transduction Pathways

194 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.Components of the mitogen activated protein kinase (MAPK) signaling cascade also localized into domains in vesicles containing acidic lipids. The formation of lateral membrane domains induced by Ki-Ras 4B and the Raf-cysteine rich domain (Raf-CRD) was inhibited by the anti-tumor agent farnesylthiosalicylic acid (FTS). The inhibition of Ras membrane domains by farnesylthiosalisylic acid was proposed to inhibit Ras function and the results provided a model of how the membrane organizes and regulates the MAP kinase signaling cascade.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Binding of basic peptides to membranes produces lateral domains enriched in the acidic lipids phosphatidylserine and phosphatidylinositol 4,5-bisphosphate: an electrostatic model and experimental results.

Direct fluorescence digital imaging microscopy observations demonstrate that a basic peptide corresponding to the effector region of the myristoylated alanine-rich C kinase substrate (MARCKS) self-assembles into membrane domains enriched in the acidic phospholipids phosphatidylserine (PS) and phosphatidylinositol 4,5-bisphosphate (PIP2). We show here that pentalysine, which corresponds to the first five residues of the MARCKS effector region peptide and binds to membranes through electrostatic interactions, also forms domains enriched in PS and PIP2. We present a simple model of domain formation that represents the decrease in the free energy of the system as the sum of two contributions: the free energy of mixing of neutral and acidic lipids and the electrostatic free energy. The first contribution is always positive and opposes domain formation, whereas the second contribution may become negative and, at low ionic strength, overcome the first contribution. Our model, based on Gouy-Chapman-Stern theory, makes four predictions: 1) multivalent basic ligands, for which the membrane binding is a steep function of the mole fraction of acidic lipid, form domains enriched in acidic lipids; domains break up at high concentrations of either 2) basic ligand or 3) monovalent salt; and 4) if multivalent anionic lipids (e.g., PIP2) are present in trace concentrations in the membrane, they partition strongly into the domains. These predictions agree qualitatively with experimental data obtained with pentalysine and spermine, another basic ligand