Hostname: page-component-586b7cd67f-t7fkt Total loading time: 0 Render date: 2024-11-27T11:10:35.383Z Has data issue: false hasContentIssue false

Phorbol-ester-induced formation of actin filaments and microtubules: role of protein kinase C

Published online by Cambridge University Press:  16 July 2018

Akio Arai
Affiliation:
Department of Biology, Faculty of Science, Toho University, Funabashi 274-8510, Japan
Tohru Nakazawa
Affiliation:
Biological Laboratory, The University of the Air, Chiba 261-8586, Japan

Extract

Cell division and motility are generated by the cytoskeletal structures contained in networks of actin filaments and microtubules. Among the Ca2+-activated protein kinases, protein kinase C (PKC) can be activated with tumor promoter, 12-O-tetradecanoyl phorbol-13-acetate (TPA) (Kikkawa et al., 1983), which induces alterations in the cytoskeleton of cultured cells. To study the regulation of the cytoskeleton by PKC, we investigated the formation of actin filaments, microtubules, changes in cell shape and Ca2+ signalling after treatment with TPA in unfertilised eggs of the sea urchin Hemicentrotus pulcherrimus.

Formation of actin filaments and microtubles was induced in the eggs by the TPA treatment. When the eggs were treated with an inactive TPA, 4α-PMA, these cytoskeletal changes did not occur. Moreover, elongation of actin filaments was inhibited by the Ca2+ chelating agent BAPTA, but microtubule organisation was unaffected by intracellular Ca2+ chelation in the TPA-treated egg. TPA is known to induce alkalisation in sea urchin eggs (Swann & Whitaker, 1985) and when the eggs are treated with TPA in Na+-free seawater, the rise in intracellular pH (pHi) is depressed. However, elongation of actin filaments and microtubules occurred under these conditions. An increase in pHi is considered to be essential for triggering the bundle of actin filaments (Begg et al., 1982) and microtubule assembly (Schatten et al., 1992). These results show that actin and microtubule assemblies require activation of PKC, and that the formation of actin and microtubules may be related to the type of PKC isoform: Ca2+-dependent or -independent. Moreover, this mechanism is essentially independent of cytoplasmic alkalisation.

Type
Special Lecture for Citizens
Copyright
Copyright © Cambridge University Press 1999

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Arai, A., Kyozuka, K. & Nakazawa, T. (1999). Cell Motil. Cytoskel. 42, 2735.Google Scholar
Begg, R.A., Rebhun, L.I. & Hyatt, H. (1982). J. Cell Biol. 93, 2432.Google Scholar
Kikkawa, U., Takai, Y., Tanaka, Y., Miyake, R. & Nishizuka, Y. (1983). J. Biol.Chem. 258, 11442–5.Google Scholar
Schatten, H., Walter, M., Biessmann, H. & Schatten, G. (1992). Cell Motil. Cytoskel. 23, 6170.Google Scholar
Swann, K. & Whitaker, M.J. (1985). Nature 314, 274–7.Google Scholar