Related Experiment Video

Updated: Jan 2, 2026

Methods to Study Mrp4-containing Macromolecular Complexes in the Regulation of Fibroblast Migration
10:43

Methods to Study Mrp4-containing Macromolecular Complexes in the Regulation of Fibroblast Migration

Published on: May 19, 2016

7.0K

PAK4 Kinase Activity Plays a Crucial Role in the Podosome Ring of Myeloid Cells

Elizabeth Foxall1, Adela Staszowska1, Liisa M Hirvonen1

  • 1Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK.

Cell Reports
|December 12, 2019
PubMed

Insights

p21-Activated kinase 4 (PAK4) regulates macrophage podosome formation and turnover. Inhibiting PAK4 reduces podosome number, promotes focal adhesions, and decreases cell migration, highlighting its kinase-dependent role in myeloid cell adhesion and matrix degradation.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Podosomes are dynamic actin-rich structures crucial for extracellular matrix degradation and cell migration in myeloid cells.
  • p21-Activated kinase 4 (PAK4) is implicated in podosome formation, but its precise role and localization remain incompletely understood.

Purpose of the Study:

  • To investigate the kinase-dependent function and localization of PAK4 in podosome dynamics.
  • To elucidate the role of PAK4 in regulating myeloid cell adhesion and migration.

Main Methods:

  • Utilized transforming growth factor β (TGF-β)-differentiated THP-1 cells.
  • Employed PAK4-targeted inhibitors and gene silencing (depletion) approaches.
  • Performed superresolution microscopy and analyzed cell adhesion and matrix degradation assays.

Main Results:

  • PAK4 inhibition significantly reduced podosome formation and promoted focal adhesion assembly, decreasing matrix degradation and cell migration.
  • Reduced PAK4 expression diminished podosome numbers, a phenotype not rescued by kinase-dead PAK4, confirming a kinase-dependent role.
  • PAK4 was localized to the podosome ring, near the actin core, and its depletion perturbed Akt phosphorylation within podosomes.

Conclusions:

  • PAK4 kinase activity is essential for regulating macrophage podosome turnover and function.
  • PAK4 interacts with the Akt pathway at the podosome ring:core interface to control podosome dynamics.
  • Targeting PAK4 offers a potential strategy to modulate myeloid cell migration and matrix degradation.
Keywords:
AKTPAK4adhesionmigrationpodosomesuperresolution microscopy

More Related Videos

Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein11:23

Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein

Published on: June 30, 2019

6.6K
Intracellular Phosphoflow Cytometry of Acute Myeloid Leukemia Patient-Derived Xenotransplants07:38

Intracellular Phosphoflow Cytometry of Acute Myeloid Leukemia Patient-Derived Xenotransplants

Published on: June 6, 2025

580

Related Concept Videos

MAPK Signaling Cascades01:07

MAPK Signaling Cascades

Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
7.7K
Mechanism of Filopodia Formation01:39

Mechanism of Filopodia Formation

Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
3.0K
The JAK-STAT Signaling Pathway01:20

The JAK-STAT Signaling Pathway

Several cytokine receptors have tightly bound Janus kinase or JAK proteins attached at their cytosolic tail. Small signaling molecules such as cytokines, growth hormones, or prolactins bind to the cytokine receptors and initiate their dimerization. The dimerization brings the cytosolic JAKs together that trans-phosphorylate and activates each other. The activated JAKs now phosphorylate cytosolic tails of the cytokine receptors, which serve as binding sites for adaptor proteins such as  SH2...
11.6K
cAMP-dependent Protein Kinase Pathways01:25

cAMP-dependent Protein Kinase Pathways

Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...
8.1K
Phosphoinositides and PIPs01:42

Phosphoinositides and PIPs

Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
10.0K
Mechanism of Lamellipodia Formation01:31

Mechanism of Lamellipodia Formation

Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...
3.5K