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  • 1
    Electronic Resource
    Electronic Resource
    LC20 and kinetics of gizzard myosin subfragment-1: Digestion with papain vs. S. aureus protease (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 23 (1992), S. 213-221 
    Details
    ISSN: 0886-1544
    Keywords: actin-activated ATPase ; LC20 cleavage ; phosphorylation ; HMM ; actin affinity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous reports have shown that papain-digested gizzard subfragment-1 (PAP-S1) has a cleaved regulatory light chain (LC20), and Vmax similar to phosphorylated heavy meromyosin (HMM) Greene et al., Biochemistry 22:530-535, 1983; Sellers et al., J. Biol. Chem. 257:13880-13883, 1982; Umemoto et al., [J. Biol. Chem. 264:1431-1436, 1989], while S. aureus protease-digested S-1 (SAP-S1) has intact LC20, but Vmax closer to that of unphosphorylated HMM [Ikebe and Hartshorne, 1985]. To determine whether intact LC20 inhibits ATPase activity for subfragment- 1 (S1), we compared the kinetic properties and structures of unphosphorylated PAP-S1 and SAP-S1. SDS-PAGE showed that SAP-S1 had 68 and 24 KDa heavy chain and 20 and 17 KDa light chain components. PAP-S1 (15 minutes digestion at 20°C) also had 68 and 17 KDa bands, but the single 24 KDa band (24HC) was replaced by a group of 22-24 KDa fragments and LC20 was cleaved to a 16 KDa fragment. At 13 mM ionic strength, both PAP-S1 and SAP-S1 had Vmax similar to phosphorylated HMM (1.1-1.5 s-1). SAP-S1 had the same KATPase as phosphorylated HMM (38 μM actin). but KATPase for PAP-S1 was 3-fold stronger (11 μM actin). Subsequent digestion of SAP-S1 with papain did not significantly change Vmax, but as LC20 and 24HC were cleaved, both KATPase and Kbinding strengthened 3- to 5-fold. Thus, intact LC20 did not inhibit, and cleavage of LC20 did not increase Vmax for S1. Rather, papain cleavage of LC20 and 24HC was associated with strengthened actin binding. © 1992 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970230305
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  • 2
    Electronic Resource
    Electronic Resource
    Structure and mass analysis of 12S and 19S dynein obtained from bull sperm flagella (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 368-374 
    Details
    ISSN: 0886-1544
    Keywords: STEM ; polypeptide composition ; ciliary motility ; dynein molecule ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Brookhaven scanning transmission electron microscpe (STEM) was used to elucidate the structures and masses of 12S and 19S dynein extracted from bull sperm flagella. The 12S particle was a single globular particle with an average mass of 311 ± 10 kdaltons. The 19S dynein particles consisted of two globular heads joined to a common base. The average mass of the 19S particle was 1.6 ± 0.04 × 106 daltons. Thus, with the exception of the larger mass, the bull sperm 19S dynein molecule resembles the two-headed 21S dynein obtained from sea urchin sperm flagella and the 18S dynein obtained from Chlamydomonas with the possibility of a third head giving rise to the 12S particle. The structure, mass and polypeptide composition of bull sperm flagella dynein is compared with outer arm dyneins previously obtained from Chlamydomonas, Tetrahymena, and sea urchin sperm flagella.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970080409
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  • 3
    Electronic Resource
    Electronic Resource
    Smooth muscle myosin subfragment-1 is a kinetic analogue for heavy meromyosin in the extended conformation (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 26 (1993), S. 291-300 
    Details
    ISSN: 0886-1544
    Keywords: conformational transition ; single turnover assays ; ionic strength ; S1/S2 junction ; actin-activated ATPase activity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The 10S→6S (Flexed→Extended) transition in smooth muscle myosin is related to increased ATPase activity, but there is controversy over whether the analogous 9S→7S transition in HMM is also associated with ATPase activity. We therefore studied the association of ionic strength, phosphorylation, and ATPase activity for HMM as compared to S1 which has no apparent flexed conformation. In addition, we performed both steady state and single turnover analyses, to control for artifacts due to multiple subfragment populations that might skew steady state results.At low ionic strength where myosin and HMM are in the flexed conformation, HMM had a near zero ATPase activity while S-1 had a high ATPase rate (0.07 s-1). At 400 mM ionic strength, where both myosin and HMM are in the extended conformation, S1 and HMM had the same ATPase rate (0.04 s-1). Phosphorylation did not affect S1 significantly, but shifted the HMM curve to higher rates at lower ionic strengths. Both steady state and single turnover experiments gave the same results, indicating that steady state results were not skewed by multiple subfragment populations. These data indicate that HMM has a conformation-ATPase relation similar to that observed with myosin. Furthermore, these findings suggest that the S1 ATPase rate corresponds to that of HMM in the extended conformation. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970260404
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  • 4
    Electronic Resource
    Electronic Resource
    Three-dimensional organization of the platelet cytoskeleton during adhesion in vitro: Observations on human and nonhuman primate cells (1983)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 589-608 
    Details
    ISSN: 0886-1544
    Keywords: platelet ; platelet adhesion ; cytoskeleton ; high voltage electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Adhesion of platelets in vitro resulted in rapid polymerization of the amorphous cytoplasmic ground substance into an organized cytoskeletal superstructure. This cytoskeleton, characterized through the use of whole-mount and stereo (3-D), high-voltage microscopy in conjunction with morphometrics and cytochemistry, comprised four major size classes of filaments organized in distinctive zones. The central matrix, or granulomere, at the center of the cell mass, was an ill-defined meshwork of 80-100-Å filaments which enshrouded granules, dense bodies, and elements of the dense tubular system as identified through peroxidase cytochemistry. Demarcasting this central matrix was a trabecular zone containing 30-50, 80-100, and 150-170 Å filaments in an open and rigid-appearing lattice. Circumscribing the trabecular zone and extending to the margins of the hyalomere was the third region, the peripheral web, in which 70-Å filaments were arranged in a tight honeycomb lattice. This organizational pattern was retained in cytoskeletons prepared by Triton x-100 extraction of the adherent cells, and was observed in basally located cells of aggregates which formed subsequent to adhesion. Our observations are consistent with biochemical studies of cytoskeletons prepared from suspended platelets and suggest a contractile protein composition for the superstructure during adhesion.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970030525
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  • 5
    Electronic Resource
    Electronic Resource
    Polymorphic assembly of subtilisin-cleaved tubulin (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 31-38 
    Details
    ISSN: 0886-1544
    Keywords: microtubule assembly ; proleolysis ; Vinca drugs ; Zn2+-induced assembly ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Limited proteolysis of tubulin with subtilisin results in cleavage of both the α and β subunits, releasing small peptides from the C-terminal ends. At 37°C the digested tubulin assembles into polymorphic structures: microtubules with attached ribbons in the presence of GTP, rings in the presence of GDP, and protofilament spirals in the presence of vinblastine. Undigested tubulin does not assemble under these conditions. Rings and Vinca-induced spiral structures are assembled from undigested tubulin only when microtubule-associated proteins, high Mg2+ concentrations, or polycations are present. Thus, cleavage with subtilisin affects assembly in a manner similar to the addition of these agents. It appears that binding of positively charged substances may act by neutralizing the charge on the highly acidic C-terminal regions of the α- and β-subunits, while cleavage with subtilisin produces the same effect by removing these peptides. Undigested and subtilisin-digested tubulin form sheets of protofilaments in the presence of Zn2+, which indicates that the binding sites for the 2-3 Zn2+ ions necessary to induce sheet formation do not reside in the C-terminal regions of the monomers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970070105
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  • 6
    Electronic Resource
    Electronic Resource
    Induction of collagenase and stromelysin gene expression by mechanical injury in a vascular smooth muscle-derived cell line (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 157 (1993), S. 426-437 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We describe a novel system for studying the production of matrix metalloproteinases types I and Ill (collagenase and stromelysin) by a vascular smooth muscle cell line (Rb-1 cells) in response to mechanical injury. Highly confluent Rb-1 cells are disrupted by passing a plastic comb around the plate to clear a series of circumferential paths, which are bordered by two ridges of displaced cells. Over the next 24 hours, cells migrate into the cleared areas. Northern blot analysis demonstrates the accumulation of mRNAs for collagenase and stromelysin during this process, although they are undetectable prior to injury. Cotreatment with all-trans-retinoic acid (10-6 M) markedly decreases the level of mRNAs induced by injury, whereas dexamethasone (10-7 M) causes only a slight reduction. In situ hybridization studies for stromelysin mRNA and immunohistochemical staining for collagenase protein on plates of injured cells showed the highest levels of stromelysin mRNA in cells in the ridges left by the injury; lower levels were observed in some cells migrating into the clear region. The same pattern of expression was observed when cells were stained with antiserum to collagenase protein. Nuclear run-on assays demonstrated increases in transcription of stromelysin and collagenase genes following injury. Transient transfection of cells with a vector containing the luciferase gene driven by a wild-type promoter comprising 1.8 kb of the 5′ flanking region of the rabbit collagenase gene showed increased activity associated with injury. We conclude that: (1) mechanical injury is associated with induction of mRNAs for the metalloproteinases collagenase and stromelysin, (2) retinoic acid effectively antagonizes this responses, and (3) the increase in steady state mRNA levels is, at least in part, transcriptionally mediated. Thus our data suggest a role for mechanical forces in initiating the changes in gene expression in vascular smooth muscle cells following arterial injury in vivo. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041570227
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  • 7
    Electronic Resource
    Electronic Resource
    Interleukin 1 stimulates prostaglandin synthesis and cyclic AMP accumulation in Swiss 3T3 fibroblasts: Interactions between two second messenger systems (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 139 (1989), S. 29-33 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Biochemical events elicited by interleukin 1 (IL-1) were studied in Swiss 3T3 fibroblasts. One hour after its addition, IL-1 stimulated synthesis of prostaglandin E2 (PGE2), which continued to accumulate for 4 days. IL-1 also stimulated cAMP accumulation. Indomethacin blocked cAMP accumulation in response to IL-1, suggesting that PG2 was responsible for the increase. Addition of exogneous PGE2 to indomethacin-treated cells restored cAMP accumulation. IL-1 enhanced thymidine incorporation, and indomethacin attenuated responses to lower concentrations. Thus, PGE2 appeared to play a role in the ability of low concentrations of IL-1 to stimulate thymidine incorporation. PGE2 augmented thymidine incorporation by increasing cAMP accumulation because in the presence of indomethacin addition of exogenous cAMP enhanced thymidine incorporation in response to low concentrations of IL-1. Elevated cAMP further stimulated PGE2 synthesis. Thus, PGE2 and cAMP interacted to potentiate their mutual accumulation. In summary, IL-1 stimulates PGE2 synthesis. PGE2, in turn, stimulates cAMP accumulation which potentiates IL-1-stimulated PGE2 synthesis and thymidine incorporation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041390106
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  • 8
    Electronic Resource
    Electronic Resource
    Both viral (adenovirus E1B) and cellular (hsp 70, p53) components interact with centrosomes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 160 (1994), S. 47-60 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human 293 cells, transformed by and expressing the early region of the adenovirus genome (i.e., E1A and E1B), contain a phase-dense cytoplasmic structure situated in close proximity to the nucleus. Via indirect immunofluorescence studies such structures have been previously shown to contain both the adenovirus E1B (55 kDa) protein as well as the tumor suppressor gene product p53. Here we show that such structures also stain positive for the cytoplasmic hsp 70 proteins. Such phase-dense structures containing hsp 70, p53, and adenovirus E1B are not unique to 293 cells but also are observed in rodent cell lines stabily transfected with the early region of the adenovirus genome. Using an antibody against a centrosomal protein, pericentrin, we show that these cytoplasmic phase-dense structures are in close proximity to the centrosome. Cell fractionation studies revealed such structures to be highly detergent insoluble. However, like the centrosome, the cytoplasmic phase-dense structures could be rendered detergent soluble following treatment of the cells with agents that disrupt the integrity of the cytoskeleton. While the phase-dense structures appear in close proximity to the centrosome in interphase cells, during mitosis the centrosome and the phasedense bodies separate from one another. Owing to these observations we examined whether hsp 70 and p53 might also co-localize with the centrosome in other cell types not expressing the adenovirus E1A/E1B proteins. We show that a portion of both hsp 70 and p53 indeed are present within the centrosome in Hela, COS, and 3T3 cells. These observations raise the possibility that components like hsp 70 and p53 may participate in the mechanism(s) controlling cell division in mammalian cells. © 1994 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041600107
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  • 9
    Electronic Resource
    Electronic Resource
    Relationship between calcium, cyclic AMP, ATP, and intracellular pH and the capacity of hamster spermatozoa to express hyperactivated motility (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 163-177 
    Details
    ISSN: 0148-7280
    Keywords: epididymal maturation ; capacitation IBMX ; calmidazolium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Capacitation of hamster caudal spermatozoa at a density of 1 × 106/ml is associated with a progressive rise in cAMP levels that precedes the onset of hyperactivated motility. This increase is not expressed by caput spermatozoa incubated under identical conditions. Both the incidence of hyperactivation and the rise in cAMP levels are severely attenuated in the absence of exogenous calcium. Neither factor is restored to control levels by the addition of the phosphodiesterase inhibitor IBMX, although in the presence of exogenous calcium, this reagent increased cAMP levels, stimulated percentage motility and advanced the appearance of hyperactivation.Treatment of spermatozoa at a density of 1 × 106/ml with the calmodulin antagonist, calmidazolium (CZ), caused severe disruption of sperm motility and abolished hyperactivation, while causing only a slight reduction in cAMP content. Addition of IBMX in the presence of CZ elevated cAMP content to levels higher than normally observed during capacitation but did not restore either coordinated or hyperactivated motility.To determine both the mechanisms responsible for this elevation of cAMP content and the changes that occur during epididymal maturation to facilitate the expression of this increase, the free cytosolic calcium concentration, ATP levels, and intracellular pH of caput and caudal cells were compared. The calcium content of caudal spermatozoa rose significantly at a time when cAMP levels were increasing, while ATP content and intracellular pH fell. However, the inability of caput spermatozoa to express a rise in cAMP content was not due to deficiencies in any of these factors.These results indicate a positive role for the cAMP rise in the expression of hyperactivated motility and that the fundamental control mechanism governing both these events may be the influx of calcium that accompanies capacitation in this species.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220205
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  • 10
    Electronic Resource
    Electronic Resource
    Action of phosphatidylcholine in protecting ram sperm from cold shock (1986)
    New York, NY : Wiley-Blackwell
    Gamete Research 15 (1986), S. 43-56 
    Details
    ISSN: 0148-7280
    Keywords: calcium ; ultrastructure ; motility ; respiration ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Rapid cooling (cold shocking) of washed ejaculated ram sperm to 0°C irreversibly reduced motility, tail beat frequency, and respiration and increased the uptake of 45Ca2+. The plasma membranes were removed from the sperm head, and the acrosomes were detached from the nuclei. The plasma membranes of the middle piece were removed, and the mitochondria contained pale and expanded cristae, similar in appearance to ATP-deprived mitochondria in the “condensed” configuration. The presence of 2.0 mg/ml phosphatidylcholine (lecithin) in the medium prevented ultrastructural damage on cold shock, and the motility, tail beat frequency, respiratory rate, and calcium uptake were maintained at levels similar to washed sperm. As the “protective” effect of phosphatidylcholine against cold shock was maintained to a certain extent after rewashing and centrifuging the sperm prior to cold shock, the interaction of phosphatidylcholine with ram sperm membranes may be fairly “tight” and not easily disrupted.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120150106
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