Motility and cytokinesis

Motility and cytokinesis: Putative Pak Organizes Myosin in Dictyostelium

Science's STKE  09 Nov 1999:
Vol. 1999, Issue 7, pp. tw1
DOI: 10.1126/stke.1999.7.tw1

Changes in the actin cytoskeleton associated with cell motility are attributed in part to the Rho family of GTP-binding proteins and their modulation of the PAK family of serine-threonine kinases. Chung and Firtel have identified a putative Pak (domain structure similar to mammalian Pak) in Dictyostelium discoideum that appears to regulate cytokinesis as well cell movement. Pak-null cells did not display normal polarized distribution of actin and exhibited defects in chemotaxis as well as in developmental aggregation. These cells also failed to undergo cytokinesis. Although Pak colocalized with myosin II in the cleavage furrow of dividing wild type cells, myosin II was not a substrate of Pak. However, the cytokinesis defect resembled the phenotype of myosin II-deficient cells. The authors hypothesize that Pak could inhibit myosin II heavy chain kinase, an enzyme that regulates the assembly of myosin II filaments. It remains to be determined whether this Pak is regulated by Rho proteins.

Chung, C.Y., and Firtel, R.A. (1999) PAKa, a putative PAK family member, is required for cytokinesis and the regulation of the cytoskeleton in Dictyostelium discoideum cells during chemotaxis. J. Cell Biol. 147: 559-575. [Abstract] [Full Text]