Effects of bivalent cations on the initiation of Na-induced pinocytosis inAmoeba proteus

Kłopocka, Wanda; Grebecka, L.

doi:10.1007/bf01281796

Cited by 5 publications

(4 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is known that incubation of amoebae with 125 mM NaCl causes increased permeability and more intensive penetration of extracellular Na þ into the cytoplasm leading to releasing Ca 2þ from intracellular compartments, and contraction of actin-cytoskeleton beneath the plasma membrane. The contraction leads to membrane invagination and formation of pinocytotic pseudopodia with pinocytotic channels [Stockem andKłopocka, 1988, Kłopocka andGrębecka, 1985]; (Fig. 10C).…”

Section: Colocalization Of Myosin VI and Dynamin Ii Immunoanalogs Witmentioning

confidence: 96%

“…An aliquot of amoeba culture was transferred to microscopic slide and 250 mM NaCl in Pringsheim medium was added in 1:1 volume ratio to induce pinocytosis [Kłopocka and Grębecka, 1985]. After 15-min incubation at room temperature, cells were fixed and permeabilized to perform immunostaining with anti-dynamin II and anti-myosin VI antibodies, as described above.…”

Section: Immunolocalization Studiesmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of Amoeba proteus myosin VI immunoanalog

Dominik

Kłopocka

Pomorski

et al. 2005

Cell Motil. Cytoskeleton

Self Cite

View full text Add to dashboard Cite

Amoeba proteus, the highly motile free-living unicellular organism, has been widely used as a model to study cell motility. However, molecular mechanisms underlying its unique locomotion and intracellular actin-based-only trafficking remain poorly understood. A search for myosin motors responsible for vesicular transport in these giant cells resulted in detection of 130-kDa protein interacting with several polyclonal antibodies against different tail regions of human and chicken myosin VI. This protein was binding to actin in the ATP-dependent manner, and immunoprecipitated with anti-myosin VI antibodies. In order to characterize its possible functions in vivo, its cellular distribution and colocalization with actin filaments and dynamin II during migration and pinocytosis were examined. In migrating amoebae, myosin VI immunoanalog localized to vesicular structures, particularly within the perinuclear and sub-plasma membrane areas, and colocalized with dynamin II immunoanalog and actin filaments. The colocalization was even more evident in pinocytotic cells as proteins concentrated within pinocytotic pseudopodia. Moreover, dynamin II and myosin VI immunoanalogs cosedimented with actin filaments, and were found on the same isolated vesicles. Blocking endogenous myosin VI immunoanalog with anti-myosin VI antibodies inhibited the rate of pseudopodia protrusion (about 19% decrease) and uroidal retraction (about 28% decrease) but did not affect cell morphology and the manner of cell migration. Treatment with anti-human dynamin II antibodies led to changes in directionality of amebae migration and affected the rate of only uroidal translocation (about 30% inhibition). These results indicate that myosin VI immunoanalog is expressed in protist Amoeba proteus and may be involved in vesicle translocation and cell locomotion.

show abstract

Section: Colocalization Of Myosin VI and Dynamin Ii Immunoanalogs Witmentioning

confidence: 96%

Section: Immunolocalization Studiesmentioning

confidence: 99%

Characterization of Amoeba proteus myosin VI immunoanalog

Dominik

Kłopocka

Pomorski

et al. 2005

Cell Motil. Cytoskeleton

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is known that incubation of amoebae with 125 mmol/L NaCl or KCl causes contraction of actin cytoskeleton beneath the plasma membrane, leading to rosette-shaped cells protruding pinocytotic pseudopodia with pinocytotic channels (Stockem et al 1983;Kłopocka and Grębecka 1985;Dominik et al 2005). After a 15 min incubation period with 125 mmol/L NaCl, amoebae were subjected to an immunostaining procedure.…”

Section: Myosin VI Immunoanalog In Pinocytotic Amoebaementioning

confidence: 99%

“…An aliquot of amoeba culture was transferred to a microscopic slide or glass chamber and then 250 mmol/L NaCl diluted with Pringsheim medium in a 1:1 volume ratio was added to induce pinocytosis (Kłopocka and Grębecka 1985). After a 15 min incubation period at room temperature, cells were further processed for either confocal or electron microscopy.…”

Section: Pinocytosismentioning

confidence: 99%

Involvement of myosin VI immunoanalog in pinocytosis and phagocytosis in Amoeba proteus

Sobczak

Wasik

Kłopocka

et al. 2008

Biochem. Cell Biol.

Self Cite

View full text Add to dashboard Cite

Recently, we found a 130-kDa myosin VI immunoanalog in amoeba, which bound to actin in an ATP-sensitive manner and in migrating amoebae colocalized to filamentous actin and dynamin II-containing vesicular structures. To further characterize this protein, we assessed its involvement in amoeba pinocytosis and phagocytosis. Confocal immunofluorescence microscopy and electron microscopy of immunogold-stained cells revealed that, in pinocytotic and phagocytotic amoebae, the myosin VI immunoanalog was visible throughout the cells, including pinocytotic channels and pinocytotic vesicles as well as phagosomes and emerging phagocytic cups. Blocking endogenous protein with anti-porcine myosin VI antibody (introduced into cells by means of microinjection) caused severe defects in pinocytosis and phagocytosis. In comparison with control cells, the treated amoebae formed ~75% less pinocytotic channels and phagocytosed ~65% less Tetrahymena cells. These data indicate that the myosin VI immunoanalog has an important role in pinocytosis and phagocytosis in Amoeba proteus (Pal.).

show abstract