PubMed Health⌕ Search

Biomedical subjects

J C Cavadore

Publications and source records attributed to J C Cavadore.

At least 55 records · Page 3Linked to original sources
PubMed1989

Further characterization of four lipocortins from human peripheral blood mononuclear cells.

Four calcium and phospholipid binding proteins purified from mononuclear cells were characterized for PKC and EGF phosphorylation, actin binding capacity, and partial tissue distribution. Those named 35K, 32K, and 73K are equivalent, respectively, to lipocortin III, endonexin II and the 67 kDa calelectrin; 36K is a fragment of 73K. After purification, 35K and 73K were phosphorylated by protein kinase C in vitro but 36K nor 32K were not. None were phosphorylated by the epidermal growth factor receptor kinase in vitro; 73K bound F-actin in a calcium-dependent manner, whereas 35K, 36K, and 32K did not. Using Western blotting analysis, 32K and 73K were detected in high amounts in human lymphocytes, monocytes, liver, and placenta and in rat adrenal medulla; but 32K was not detected in polymorphonuclear cells, and 36K and 35K were detected in high amounts only, respectively, in human blood lymphocytes and polymorphonuclear cells. Thus, 32K and 73K appear to have a wide tissue distribution, whereas 35K has a much more restricted distribution.

Actins↗
PubMed1989

High-molecular-mass proteins in haemodialysis-associated amyloidosis.

1. Protein constituents were determined in eight amyloid deposits from eight patients (five male and three female), 53 +/- 4 years of age, treated by haemodialysis for 9-20 years using only cuprophane membranes and operated for carpal tunnel syndrome. 2. Soluble proteins were removed by solubilization in phosphate-buffered saline after osmotic lysis. The proteins of the insoluble fibrils were characterized by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and two-dimensional gel electrophoresis, and immunologically identified by Western blotting. 3. In addition to beta 2-microglobulin, alpha 2-macroglobulin was identified in the fibrillar material. The presence of these two proteins in amyloid deposits was confirmed by immunofluorescent microscopic studies. 4. Our data confirm the presence of beta 2-microglobulin in haemodialysis-associated amyloidosis, and also suggest a possible role for alpha 2-microglobulin: it may protect beta 2-microglobulin from proteolytic digestion, leading to its accumulation in intact form and to amyloid fibril formation.

Amyloid↗
PubMed1988

Structural and functional variations in skeletal-muscle and scallop muscle actins.

Structural and functional properties in two striated-muscle actins, one from a vertebrate, the other from an invertebrate (scallop), were compared in relation to a smooth-muscle actin isoform (aortic actin). In spite of differences in the variable N-terminal region, the two striated-muscle isoactins showed, in contrast with aortic actin, a large structural homology revealed by proteinase-susceptibility and interaction with the myosin head. Thus the myosin head may bind to the two striated-muscle actins in constant parts of the 18-113 sequence. In contrast, antigenic reactivity of conformational epitopes of these actins strongly differentiated scallop actin from the two others. The behaviour of the scallop actin appears to be related to several amino acid substitutions located near or at functional domains such as monomer-monomer binding site, DNAase-I-dependent actin-actin binding site and actin-severing domain, which modified the polypeptide chain exposure.

Actins↗
PubMed1988

Modulation of the accumulation of inositol phosphates and the mobilization of calcium in aortic myocytes.

In vascular smooth muscle cells the phorbol ester, 12-O-tetradecanoyl phorbol 13-acetate (TPA), a potent activator of C-kinase, inhibited the accumulation of inositol phosphates and the mobilization of calcium produced by several agonists. In the same way, TPA inhibited the fluoride-induced activation of phosphoinositide metabolism. These results suggest a C-kinase action at a post-receptor level. Moreover, the fluoride-induced accumulation of inositol phosphates shows the presence of one or more guanine nucleotide-binding proteins (G-proteins) in the regulation of receptor-phospholipase C coupling. This was confirmed by the use of N-ethylmaleimide and pertussis toxin. These results support the view that, in addition to the induction of sustained contractions, C-kinase can activate negative feedback mechanisms in aortic myocytes.

Animals↗
PubMed1988

A 36 kDa monomeric protein and its complex with a 10 kDa protein both isolated from bovine aorta are calpactin-like proteins that differ in their Ca2+-dependent calmodulin-binding and actin-severing properties.

Interaction of plasma membrane with the cytoskeleton involves a large number of proteins, among them a 36 kDa protein that was found to be involved in the interaction with actin filaments. We have isolated a 36 kDa protein from bovine aorta as a monomer and in a complex with a 10 kDa protein. Partial amino acid sequence determinations show that the 36 kDa and 10 kDa proteins isolated from bovine aorta are analogous to or identical with corresponding proteins purified from bovine intestine already described by Kristensen, Saris, Hunter, Hicks, Noonan, Glenney & Tack [(1986) Biochemistry 25, 4497-4503]. We report here that the association of the 10 kDa protein with the 36 kDa protein confers specific calmodulin-binding and actin-severing properties on the complex that are not possessed by the 36 kDa monomer alone. These findings suggest that the protein complex could be involved in thin-filament-related structures or could modulate some Ca2+-regulated events mediated by calmodulin.

Actins↗
PubMed1988

The effects of maitotoxin on phosphoinositides and calcium metabolism in a primary culture of aortic smooth muscle cells.

Maitotoxin, a potent marine toxin isolated from toxic tropical dinoflagellates and poisonous fishes induces contraction of different smooth muscle preparations. Actions of maitotoxin on phosphoinositides and calcium metabolism were studied using a primary culture of aortic smooth muscle cells. Maitotoxin induced a very large increase of cytosolic calcium concentration as evaluated by fura-2 acetoxymethyl ester fluorescence. This increase was concomitant with stimulation of inositol-phosphate accumulation and loss of viability of aortic smooth muscle cells. These responses to maitotoxin were abolished in Ca2+-free medium, and were mimicked by saponin. Calcium ionophores or K+ depolarisation did not induce inositol-phosphate formation. These results suggest that maitotoxin acts by altering smooth muscle cells permeability allowing a sustained calcium influx which is able to activate inositol-phosphate formation and which is lethal for the cells.

Angiotensin II↗
PubMed1988

Phorbol ester modulation of cyclic AMP accumulation in a primary culture of rat aortic smooth muscle cells.

Over the past few years, the importance of calcium and cyclic AMP in the regulation of vascular smooth muscle tone has been well documented. We used a primary culture of rat aortic myocytes to study the effect of protein kinase C on isoproterenol- and forskolin-stimulated cyclic AMP production. Addition of the protein kinase C activator 12-O-tetradecanoylphorbol-13-acetate (TPA) to these cells, but not an inactive analog, increased the stimulation of cyclic AMP production induced with isoproterenol or forskolin without changes in the apparent affinity of these compounds but did not affect the basal cAMP level. TPA also enhanced the cholera toxin-stimulated cyclic AMP accumulation. Isoproterenol and cholera toxin increased the forskolin apparent potency suggesting that interaction of activatory GTP-dependent protein with the catalytic subunit of adenylate cyclase facilitates forskolin interaction to the catalytic subunit. Treatment of myocytes with pertussis toxin had no effect on the basal level of cyclic AMP production and did not significantly modify isoproterenol- and forskolin-induced stimulation. Pertussis toxin treatment of cells did not affect the TPA-enhanced isoproterenol or forskolin stimulations suggesting that pertussis toxin and TPA actions would not share a common target of myocyte adenylate cyclase system. Our data would be in agreement with a possible direct interaction of protein kinase C with the catalytic subunit of adenylate cyclase system.

Adenylate Cyclase Toxin↗
PubMed1987

Sequence homologies between p36, the substrate of pp60src tyrosine kinase and a 67 kDa protein isolated from bovine aorta.

A 67 kDa actin-binding protein was isolated from bovine aorta. Partial amino acid sequence determination of two large thermolysin peptides were used to compare 67 kDa bovine aorta protein and p36 the substrate of pp60src tyrosine kinase. Sequence analysis shows that 67 kDa bovine aorta protein shares common domains with p36 and possesses the consensus aminoacid sequences of mammalian Ca2+-dependent membrane-binding protein and p36/gelsolin.

Amino Acid Sequence↗
PubMed1987

ATP stimulates inositol phosphates accumulation and calcium mobilization in a primary culture of rat aortic myocytes.

The effects of extracellular ATP on phosphoinositide metabolism and intracellular Ca2+ concentration were studied in a primary culture of rat aortic myocytes. ATP increases the level of inositol phosphates, the putative second messenger for Ca2+ mobilization. No saturation of inositol phosphates accumulation is obtained (up to 10(-2) M ATP). Under the same conditions, ATP rapidly mobilizes intracellular Ca2+ in fura-2 loaded myocytes. The mobilization of intracellular Ca2+ is dose-dependent (maximal at 10(-4) M ATP), and is not affected by addition of EGTA. It is concluded that the receptors mediating the cytosolic increase of Ca2+ are of the P2-purinoceptor subtype. The physiological functions of these receptors are not presently known.

Adenosine Triphosphate↗
PubMed1987

Actin antibodies. Preparation and characterization of antibodies specific for smooth-muscle actin isoforms.

We have determined the specificity of sera elicited by glutaraldehyde-stabilized bovine aortic actin. This modification induces a high titre of antibodies directed against the N-terminal (residues 1-39) and the C-terminal region of smooth-muscle actins. The crude antisera were purified on peptide (corresponding to the 1-9 or 1-8 N-terminal sequences of smooth-muscle isoactins)-polyacrylic-resin columns. By fractionating the antisera we obtained oligoclonal antibody populations specific for each isoactin.

Actins↗
PubMed1987

Acute adaptative changes to unilateral nephrectomy in humans.

Renal function was monitored in 20, living-related kidney donors before and after uninephrectomy. Urinary protein excretion and retinoid metabolism respectively were studied in 10 and 6 of these donors. The functional adaptation was characterized by an increase in glomerular filtration rate and tubular function, which began in the first two days after uninephrectomy. Changes in tubular function were also demonstrated by significant increases in the urinary excretion of beta 2 microglobulin (beta 2M), retinol binding protein (RBP), kappa and lambda light chains of immunoglobulins. In addition, a protein identical to or homologous to cellular retinoic acid binding protein (CRABP), appeared in the urine after nephrectomy. We did not find CRABP in serum samples either before or after nephrectomy, suggesting that urinary CRABP was synthesized by the remaining kidney. Increases in serum levels of Vitamin A and RBP were also observed in the post-nephrectomy period. These modifications in retinol metabolism suggest that these substances could have a role as renotropic growth factors in compensatory hypertrophy.

Adult↗
PubMed1987

Haemodialysis-associated amyloidosis: beta 2-microglobulin alone or associated with globin chains?

1. The protein constituents of amyloid fibrils were characterized in amyloid deposits extracted from surgical material obtained from a 66-year-old patient undergoing maintenance haemodialysis and operated for a carpal tunnel syndrome. 2. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis disclosed the presence of bands at 12 and 14 kDa. Two-dimensional electrophoresis and Western blotting confirmed that the proteins were beta 2-microglobulin (beta 2M) and globin chains. 3. When the effluent of high-performance gel filtration chromatography corresponding to molecular masses of 10-15 kDa was subjected to Edman degradation, only one amino acid residue was found at each step. The 18 residues determined corresponded to the N-terminal sequence of beta 2M. 4. Although globin chains were clearly present in the amyloid material, they were not accessible for sequence determination. The identification of the other protein constituents present in the amyloid material, along with beta 2M, should provide a better understanding of haemodialysis-associated amyloidosis, the mechanisms of formation of which have not yet been completely determined.

Aged↗
PubMed1987

[Amyloid deposits in hemodialysis patients: immunochemical analysis].

We have analyzed 9 amyloid deposits isolated from 7 patients treated by long-term hemodialysis [6] and/or hemofiltration [1] for 8 to 19 years. Amyloid deposits were extracted from carpal tunnel synovitis [7] or femoral bone [2]. Proteins were analyzed by SDS-PAGE, two-dimensional electrophoresis and the identification was made by Western Blotting and specific antibody fixation. Several proteins were found: immunoglobulin light chains, beta 2 microglobulin (B2M), as well as globin chains, albumin and hemopexin. These findings suggest that amyloid deposits are not only made of B2M, but also with other protein species not cleared by dialysis membranes. Among these proteins, B2M and immunoglobulin light chains have well known amyloidogenic properties. We suggest that the role played by the remaining proteins on the pathogenesis of dialysis associated amyloidosis should also be considered.

Adult↗
PubMed1986

Evidence for two distinct adenylate cyclase catalysts in rat brain.

The Lubrol-soluble adenylate cyclase activity of brain synaptosomal membranes appeared, upon gel filtration or sucrose gradient centrifugation, as two overlapping peaks. Fractions corresponding to the peak of the largest Stokes radius (Biogel pool 1) or highest s value (gradient pool 1) contained an adenylate cyclase activity which could be detected whatever the enzyme assay conditions. In contrast, in fractions from the second peak (Biogel pool 2 or gradient pool 2), forskolin was needed to reveal adenylate cyclase activity. The enzyme activity of each Biogel pool was retained by forskolin-agarose and eluted by forskolin with a 34-83% yield. A polypeptide of 155 kDa made up 80% of the forskolin-agarose eluate 1, whereas it was almost absent from eluate 2. Since data from various groups point to the 155 kDa polypeptide as a brain adenylate cyclase catalyst, still another distinct catalyst of lower molecular mass is likely to be present in brain.

Adenylyl Cyclases↗
PubMed1986

Structural variations in actins. A study of the immunological reactivity of the N-terminal region.

The antigenicity of the N-terminal region of skeletal-muscle actin was analysed. Two epitopes, corresponding to the 1-7 and 18-28 sequences, were determined. The antibodies specific for the first epitope discriminate skeletal-muscle actin from cardiac-muscle and smooth-muscle actins. The antibodies specific for the second epitope interact with all the actins tested, ranging from invertebrate to higher-vertebrate actins.

Actins↗
PubMed1985

Structural variations in actins. Biochemical and immunological tools for probing the structure of rabbit skeletal-muscle and bovine aortic actins.

Structural differences between skeletal-muscle and aortic actins were studied by using biochemical and immunological approaches. By using proteinase digestion we found that three regions of actin show structural differences: (a) in the C-terminal part, (b) the region around residue 227 and (c) the region around residue 167. By using antibodies specific to particular actin conformations we can discriminate between monomeric and filamentous forms of the two actins. Our results show that the minor sequence variations of the N- and C-terminal regions induce structural change in these regions, but also some long-range structural variations in other regions.

Actins↗
PubMed1985

Calcium binding of arterial tropomyosin: involvement in the thin filament regulation of smooth muscle.

Bovine aortic tropomyosin has been isolated by DEAE-Sepharose chromatography following isoelectric precipitation and ammonium sulfate fractionation. A single polypeptide [Mr 36 000 on a sodium dodecyl sulfate (SDS)-polyacrylamide gel] was obtained under different electrophoretic conditions. The amino acid composition of bovine tropomyosin was very similar to that of rabbit skeletal muscle; the amino-terminal residue is blocked. The molecular weight of the native tropomyosin (76 000), which is twice that calculated from the SDS-polyacrylamide gel, suggests that the molecule is a dimer. The diffusion coefficient of 3.4 X 10(-7) cm2 s-1 and the frictional coefficient of 1.7 indicate that the molecule is asymmetric. Comparative high-pressure liquid chromatography peptide mapping of rabbit skeletal and bovine aortic tropomyosins shows primary structure variation. Bovine aortic tropomyosin binds calcium under physiological conditions of pH and ionic strength (22 mol of Ca2+/mol of tropomyosin with a Kd of 1.4 mM). Such a property is not shared by skeletal tropomyosin. In low Mg2+ concentration, both skeletal and aortic actin activations of the skeletal myosin ATPase activity are calcium independent. Addition of aortic tropomyosin to a hybrid actomyosin (aortic actin, skeletal myosin) yields an enhancement of the actin activation of the myosin ATPase activity, but the addition of skeletal tropomyosin yields a decrease of this activity. However, both the enhancement and decrease are calcium dependent. Addition of skeletal or aortic tropomyosin to an actomyosin system, where both actin and myosin come from skeletal muscle, yields only an enhancement of the actin activation of the myosin ATPase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Actin Cytoskeleton↗