Daniel Walz and Georg Rosenberger contributed equally to the manuscript.
PAK4 and αPIX determine podosome size and number in macrophages through localized actin regulation†
Article first published online: 8 AUG 2006
Copyright © 2006 Wiley-Liss, Inc.
Journal of Cellular Physiology
Volume 209, Issue 2, pages 568–579, November 2006
How to Cite
Gringel, A., Walz, D., Rosenberger, G., Minden, A., Kutsche, K., Kopp, P. and Linder, S. (2006), PAK4 and αPIX determine podosome size and number in macrophages through localized actin regulation. J. Cell. Physiol., 209: 568–579. doi: 10.1002/jcp.20777
- Issue published online: 29 AUG 2006
- Article first published online: 8 AUG 2006
- Manuscript Accepted: 27 JUN 2006
- Manuscript Received: 26 MAY 2006
- Deutsche Forschungsgemeinschaft, Bonn, Germany. Grant Numbers: GRK 438, SFB 413, SFB 444
Podosomes are actin-rich adhesion structures typical for monocytic cells and are implicated in migration and invasion. Major modes of podosome regulation include RhoGTPase signaling and actin regulatory pathways. However, it is not clearly understood how these signals induce highly localized changes in podosome formation and dynamics. Here, we show that the RhoGTPase effector PAK4, a member of the p21 associated kinase family, and its regulator αPIX (PAK-interacting exchange factor), are central to podosome formation in primary human macrophages. Immunofluorescence, biochemical and microarray data indicate that PAK4 acts as physiological regulator of podosomes in this system. Accordingly, transfection of a specific shRNA, as well as expression of PAK4 truncation mutants, resulted in reduced numbers of podosomes per cell. Moreover, expression of kinase active or inactive PAK4 mutants enhanced or reduced the size of individual podosomes, respectively, indicating a modulatory influence of PAK4 kinase activity on podosome size. Similar to the results gained with PAK4, cellular/overexpressed PIX was shown to be closely associated with podosomes. Moreover, both overexpression of αPIX wt and a mutant lacking the SH3 domain led to coalescence of podosomes. In sum, we propose that PAK4 and αPIX can induce highly localized changes in actin dynamics and thereby regulate size and number of podosomes in primary human macrophages. J. Cell. Physiol. 209: 568–579, 2006. © 2006 Wiley-Liss, Inc.