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J Cell Biol. 1995 December 2; 131(6): 1495–1506.
PMCID: PMC2120683

Ponticulin plays a role in the positional stabilization of pseudopods


Ponticulin is a 17-kD glycoprotein that represents a major high affinity link between the plasma membrane and the cortical actin network of Dictyostelium. To assess the role of ponticulin in pseudopod extension and retraction, the motile behavior of two independently generated mutants lacking ponticulin was analyzed using computer- assisted two- and three-dimensional motion analysis systems. More than half of the lateral pseudopods formed off the substratum by ponticulin- minus cells slipped relative to the substratum during extension and retraction. In contrast, all pseudopods formed off the substratum by wild-type cells were positionally fixed in relation to the substratum. Ponticulin-minus cells also formed a greater proportion of both anterior and lateral pseudopods off the substratum and absorbed a greater proportion of lateral pseudopods into the uropod than wild-type cells. In a spatial gradient of cAMP, ponticulin-minus cells were less efficient in tracking the source of chemoattractant. Since ponticulin- minus cells extend and retract pseudopods with the same time course as wild-type cells, these behavioral defects in ponticulin-minus cells appear to be the consequence of pseudopod slippage. These results demonstrate that pseudopods formed off the substratum by wild-type cells are positionally fixed in relation to the substratum, that ponticulin is required for positional stabilization, and that the loss of ponticulin and the concomitant loss of positional stability of pseudopods correlate with a decrease in the efficiency of chemotaxis.

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Selected References

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  • Abercrombie M, Heaysman JE, Pegrum SM. The locomotion of fibroblasts in culture. I. Movements of the leading edge. Exp Cell Res. 1970 Mar;59(3):393–398. [PubMed]
  • Abercrombie M, Heaysman JE, Pegrum SM. The locomotion of fibroblasts in culture. II. "RRuffling". Exp Cell Res. 1970 Jun;60(3):437–444. [PubMed]
  • Alexander S, Sydow LM, Wessels D, Soll DR. Discoidin proteins of Dictyostelium are necessary for normal cytoskeletal organization and cellular morphology during aggregation. Differentiation. 1992 Nov;51(3):149–161. [PubMed]
  • Bray D, White JG. Cortical flow in animal cells. Science. 1988 Feb 19;239(4842):883–888. [PubMed]
  • Caterina MJ, Devreotes PN. Molecular insights into eukaryotic chemotaxis. FASEB J. 1991 Dec;5(15):3078–3085. [PubMed]
  • Chandrasekhar A, Wessels D, Soll DR. A mutation that depresses cGMP phosphodiesterase activity in Dictyostelium affects cell motility through an altered chemotactic signal. Dev Biol. 1995 May;169(1):109–122. [PubMed]
  • Chia CP, Hitt AL, Luna EJ. Direct binding of F-actin to ponticulin, an integral plasma membrane glycoprotein. Cell Motil Cytoskeleton. 1991;18(3):164–179. [PubMed]
  • Cocucci SM, Sussman M. RNA in cytoplasmic and nuclear fractions of cellular slime mold amebas. J Cell Biol. 1970 May;45(2):399–407. [PMC free article] [PubMed]
  • Condeelis J. Life at the leading edge: the formation of cell protrusions. Annu Rev Cell Biol. 1993;9:411–444. [PubMed]
  • Condeelis J, Jones J, Segall JE. Chemotaxis of metastatic tumor cells: clues to mechanisms from the Dictyostelium paradigm. Cancer Metastasis Rev. 1992 Mar;11(1):55–68. [PubMed]
  • Cox D, Condeelis J, Wessels D, Soll D, Kern H, Knecht DA. Targeted disruption of the ABP-120 gene leads to cells with altered motility. J Cell Biol. 1992 Feb;116(4):943–955. [PMC free article] [PubMed]
  • De Lozanne A, Spudich JA. Disruption of the Dictyostelium myosin heavy chain gene by homologous recombination. Science. 1987 May 29;236(4805):1086–1091. [PubMed]
  • Doolittle KW, Reddy I, McNally JG. 3D analysis of cell movement during normal and myosin-II-null cell morphogenesis in dictyostelium. Dev Biol. 1995 Jan;167(1):118–129. [PubMed]
  • Downey GP. Mechanisms of leukocyte motility and chemotaxis. Curr Opin Immunol. 1994 Feb;6(1):113–124. [PubMed]
  • Hitt AL, Lu TH, Luna EJ. Ponticulin is an atypical membrane protein. J Cell Biol. 1994 Sep;126(6):1421–1431. [PMC free article] [PubMed]
  • Hitt AL, Hartwig JH, Luna EJ. Ponticulin is the major high affinity link between the plasma membrane and the cortical actin network in Dictyostelium. J Cell Biol. 1994 Sep;126(6):1433–1444. [PMC free article] [PubMed]
  • Jay PY, Elson EL. Surface particle transport mechanism independent of myosin II in Dictyostelium. Nature. 1992 Apr 2;356(6368):438–440. [PubMed]
  • Knecht DA, Loomis WF. Antisense RNA inactivation of myosin heavy chain gene expression in Dictyostelium discoideum. Science. 1987 May 29;236(4805):1081–1086. [PubMed]
  • Luna EJ, Hitt AL. Cytoskeleton--plasma membrane interactions. Science. 1992 Nov 6;258(5084):955–964. [PubMed]
  • Luna EJ, Wuestehube LJ, Chia CP, Shariff A, Hitt AL, Ingalls HM. Ponticulin, a developmentally-regulated plasma membrane glycoprotein, mediates actin binding and nucleation. Dev Genet. 1990;11(5-6):354–361. [PubMed]
  • Murray J, Vawter-Hugart H, Voss E, Soll DR. Three-dimensional motility cycle in leukocytes. Cell Motil Cytoskeleton. 1992;22(3):211–223. [PubMed]
  • Pasternak C, Spudich JA, Elson EL. Capping of surface receptors and concomitant cortical tension are generated by conventional myosin. Nature. 1989 Oct 12;341(6242):549–551. [PubMed]
  • Schindl M, Wallraff E, Deubzer B, Witke W, Gerisch G, Sackmann E. Cell-substrate interactions and locomotion of Dictyostelium wild-type and mutants defective in three cytoskeletal proteins: a study using quantitative reflection interference contrast microscopy. Biophys J. 1995 Mar;68(3):1177–1190. [PubMed]
  • Shariff A, Luna EJ. Dictyostelium discoideum plasma membranes contain an actin-nucleating activity that requires ponticulin, an integral membrane glycoprotein. J Cell Biol. 1990 Mar;110(3):681–692. [PMC free article] [PubMed]
  • Sheetz MP. Cellular plasma membrane domains. Mol Membr Biol. 1995 Jan-Mar;12(1):89–91. [PubMed]
  • Soll DR, Voss E, Varnum-Finney B, Wessels D. "Dynamic Morphology System": a method for quantitating changes in shape, pseudopod formation, and motion in normal and mutant amoebae of Dictyostelium discoideum. J Cell Biochem. 1988 Jun;37(2):177–192. [PubMed]
  • Sylwester A, Wessels D, Anderson SA, Warren RQ, Shutt DC, Kennedy RC, Soll DR. HIV-induced syncytia of a T cell line form single giant pseudopods and are motile. J Cell Sci. 1993 Nov;106(Pt 3):941–953. [PubMed]
  • Sylwester A, Shutt D, Wessels D, Stapleton JT, Stites J, Kennedy RC, Soll DR. T cells and HIV-induced T cell syncytia exhibit the same motility cycle. J Leukoc Biol. 1995 Apr;57(4):643–650. [PubMed]
  • Titus MA, Wessels D, Spudich JA, Soll D. The unconventional myosin encoded by the myoA gene plays a role in Dictyostelium motility. Mol Biol Cell. 1993 Feb;4(2):233–246. [PMC free article] [PubMed]
  • Varnum B, Soll DR. Effects of cAMP on single cell motility in Dictyostelium. J Cell Biol. 1984 Sep;99(3):1151–1155. [PMC free article] [PubMed]
  • Varnum B, Edwards KB, Soll DR. The developmental regulation of single-cell motility in Dictyostelium discoideum. Dev Biol. 1986 Jan;113(1):218–227. [PubMed]
  • Varnum-Finney B, Edwards KB, Voss E, Soll DR. Amebae of Dictyostelium discoideum respond to an increasing temporal gradient of the chemoattractant cAMP with a reduced frequency of turning: evidence for a temporal mechanism in ameboid chemotaxis. Cell Motil Cytoskeleton. 1987;8(1):7–17. [PubMed]
  • Varnum-Finney BJ, Voss E, Soll DR. Frequency and orientation of pseudopod formation of Dictyostelium discoideum amebae chemotaxing in a spatial gradient: further evidence for a temporal mechanism. Cell Motil Cytoskeleton. 1987;8(1):18–26. [PubMed]
  • Wessels D, Soll DR. Myosin II heavy chain null mutant of Dictyostelium exhibits defective intracellular particle movement. J Cell Biol. 1990 Sep;111(3):1137–1148. [PMC free article] [PubMed]
  • Wessels D, Soll DR, Knecht D, Loomis WF, De Lozanne A, Spudich J. Cell motility and chemotaxis in Dictyostelium amebae lacking myosin heavy chain. Dev Biol. 1988 Jul;128(1):164–177. [PubMed]
  • Wessels D, Schroeder NA, Voss E, Hall AL, Condeelis J, Soll DR. cAMP-mediated inhibition of intracellular particle movement and actin reorganization in Dictyostelium. J Cell Biol. 1989 Dec;109(6 Pt 1):2841–2851. [PMC free article] [PubMed]
  • Wessels D, Murray J, Jung G, Hammer JA, 3rd, Soll DR. Myosin IB null mutants of Dictyostelium exhibit abnormalities in motility. Cell Motil Cytoskeleton. 1991;20(4):301–315. [PubMed]
  • Wessels D, Murray J, Soll DR. Behavior of Dictyostelium amoebae is regulated primarily by the temporal dynamic of the natural cAMP wave. Cell Motil Cytoskeleton. 1992;23(2):145–156. [PubMed]
  • Wessels D, Vawter-Hugart H, Murray J, Soll DR. Three-dimensional dynamics of pseudopod formation and the regulation of turning during the motility cycle of Dictyostelium. Cell Motil Cytoskeleton. 1994;27(1):1–12. [PubMed]
  • Wuestehube LJ, Luna EJ. F-actin binds to the cytoplasmic surface of ponticulin, a 17-kD integral glycoprotein from Dictyostelium discoideum plasma membranes. J Cell Biol. 1987 Oct;105(4):1741–1751. [PMC free article] [PubMed]
  • Wuestehube LJ, Chia CP, Luna EJ. Indirect immunofluorescence localization of ponticulin in motile cells. Cell Motil Cytoskeleton. 1989;13(4):245–263. [PubMed]
  • Zigmond SH. Ability of polymorphonuclear leukocytes to orient in gradients of chemotactic factors. J Cell Biol. 1977 Nov;75(2 Pt 1):606–616. [PMC free article] [PubMed]

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