Actin dynamics in Amoeba proteus motility

We studied the distribution of the endogenous Arp2/3 complex in Amoeba proteus and visualised the ratio of filamentous (F-actin) to total actin in living cells. The presented results show that in the highly motile Amoeba proteus, Arp2/3 complex-dependent actin polymerisation is involved in the forma...

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Bibliographic Details
Published in:Protoplasma 2007-07, Vol.231 (1-2), p.31-41
Main Authors: Pomorski, P, Krzemiński, P, Wasik, A, Wierzbicka, K, Barańska, J, Kłopocka, W
Format: Article
Language:English
Subjects:
Actin
Actin-Related Protein 2-3 Complex - metabolism
Actins - metabolism
Amoeba
Amoeba - cytology
Amoeba - ultrastructure
Amoeba proteus
Animals
Arp2/3 complex
cell motility
Contractility
Cytoskeleton
endocytosis
Isometric
Microfilaments
Muscle contraction
Pinocytosis
Polymerization
Protein Transport
Proteins
Pseudopodia
Ratio of filamentous to total actin
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Summary:We studied the distribution of the endogenous Arp2/3 complex in Amoeba proteus and visualised the ratio of filamentous (F-actin) to total actin in living cells. The presented results show that in the highly motile Amoeba proteus, Arp2/3 complex-dependent actin polymerisation is involved in the formation of the branching network of the contractile layer, adhesive structures, and perinuclear cytoskeleton. The aggregation of the Arp2/3 complex in the cortical network, with the exception of the uroid and advancing fronts, and the spatial orientation of microfilaments at the leading edge suggest that actin polymerisation in this area is not sufficient to provide the driving force for membrane displacement. The examined proteins were enriched in the pinocytotic pseudopodia and the perinuclear cytoskeleton in pinocytotic amoebae. In migrating amoebae, the course of changes in F-actin concentration corresponded with the distribution of tension in the cell cortex. The maximum level of F-actin in migrating amoebae was observed in the middle-posterior region and in the front of retracting pseudopodia. Arp2/3 complex-dependent actin polymerisation did not seem to influence F-actin concentration. The strongly condensed state of the microfilament system could be attributed to strong isometric contraction of the cortical layer accompanied by its retraction from distal cell regions. Isotonic contraction was limited to the uroid.
ISSN:0033-183X
1615-6102
DOI:10.1007/s00709-007-0243-1