Role of Group A p21-activated Kinases in Activation of Extracellular-regulated Kinase by Growth Factors

Cell movement requires morphological polarization characterized by formation of a leading pseudopodium (PD) at the front and a trailing rear at the back. However, little is known about how protein networks are spatially integrated to regulate this process at the system level. Here, we apply global proteome profiling in combination with newly developed quantitative phosphoproteomics approaches for comparative analysis of the cell body (CB) and PD proteome of chemotactic cells. The spatial relationship of 3,509 proteins and 228 distinct sites of phosphorylation were mapped revealing networks of signaling proteins that partition to the PD and/or the CB compartments. The major network represented in the PD includes integrin signaling, actin regulatory, and axon guidance proteins, whereas the CB consists of DNA/RNA metabolism, cell cycle regulation, and structural maintenance. Our findings provide insight into the spatial organization of signaling networks that control cell movement and provide a comprehensive system-wide profile of proteins and phosphorylation sites that control cell polarization.bioinformatics ͉ chemotaxis ͉ phosphoproteomics ͉ proteomics ͉ cell migration D irected cell migration or chemotaxis in response to a chemokine gradient is involved in development, immune function, angiogenesis, as well as pathological processes associated with inflammation and cancer cell metastasis (1). Cell locomotion is a highly polarized process characterized by protrusion of a leading pseudopodium (PD) (lamellipodium) at the front and establishment of a trailing rear compartment or tail region at the back (1, 2). This process is regulated through organization of the actin-myosin cytoskeleton in response to signal transduction processes that operate downstream of chemokine and integrin adhesion receptors. These receptors serve as antennae to sense changes in chemokine and extracellular matrix gradients, which provide navigational cues to direct cell movement. However, the molecular signaling mechanisms that control cell polarity and chemotaxis are not fully understood.Emerging evidence indicates that cell behavior is regulated by the complex organization of multiple signaling networks in time and space. The specific propagation of biological information in a complex biological system is achieved through the spatiotemporal assembly of multiprotein scaffolds, protein activation cascades, protein turnover, and specific posttranslational modifications of proteins, including the phosphorylation and dephosphorylation of specific amino acid residues. Although significant progress has been made in identification of specific signaling proteins and regulatory pathways that mediate cell migration, little is known about how these signals are integrated into spatial networks to achieve morphological polarity and directional movement at a system level.To understand the complexity of signal organization in migrating cells, our laboratory developed a system that facilitates the differential purification of the PD and cell body (CB) co...

show abstract

“…Finally, the activity of ERK could also be enhanced by Integrin-signaling components, which are highly enriched in the PD (Fig. 4B) (30).…”

Section: Characterization Of the Ras/erk-signaling Pathway In The Pd Bymentioning

confidence: 99%

Profiling signaling polarity in chemotactic cells

Wang

Ding

Wang

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…IB␣M and p65 cloned into PLZRS (provided by P. Khavari, Stanford Medical Center, CA) were used directly. Adenovirus Tet, V12Rac, V12Rac H40, PID, Pak1 WT, and HA-tagged ␤2-chimerin have been described previously (Beeser et al, 2005;Tang et al, 1999;Yang et al, 2005), and were expanded and virus was purified by cesium chloride banding (He et al, 1998). 3D MEC tissue structures were generated using a polyHEMA-rBM suspension culture (Weaver et al, 2002), and polarized acini were then isolated in PBS supplemented with 10 mM EDTA, infected with adenovirus (15 minutes; 37°C), and transgene expression was confirmed by immunofluorescence microscopy and immunoblot and Rac GTPase activity assay.…”

mentioning

confidence: 99%

α6β4 integrin activates Rac-dependent p21-activated kinase 1 to drive NF-κB-dependent resistance to apoptosis in 3D mammary acini

Friedland

Lakins

Kazanietz

et al. 2007

Journal of Cell Science

Self Cite

View full text Add to dashboard Cite

Malignant transformation and multidrug resistance are linked to resistance to apoptosis, yet the molecular mechanisms that mediate tumor survival remain poorly understood. Because the stroma can influence tumor behavior by regulating the tissue phenotype, we explored the role of extracellular matrix signaling and tissue organization in epithelial survival. We report that elevated (α6)β4 integrin-dependent Rac-Pak1 signaling supports resistance to apoptosis in mammary acini by permitting stress-dependent activation of the p65 subunit of NF-κB through Pak1. We found that inhibiting Pak1 through expression of N17Rac or PID compromises NF-κB activation and renders mammary acini sensitive to death, but that resistance to apoptosis could be restored to these structures by overexpressing wild-type NF-κB p65. We also observed that acini expressing elevated levels of Pak1 can activate p65 and survive death treatments, even in the absence of activated Rac, yet will die if activation of NF-κB is simultaneously inhibited through expression of IκBαM. Thus, mammary tissues can resist apoptotic stimuli by activating NF-κB through α6β4 integrin-dependent Rac-Pak1 signaling. Our data emphasize the importance of the extracellular matrix stroma in tissue survival and suggest that α6β4 integrin-dependent Rac stimulation of Pak1 could be an important mechanism mediating apoptosis-resistance in some breast tumors.

show abstract

“…Furthermore, Pak1 phosphorylates and activates MEK1 (Slack-Davis et al, 2003), ERK1/2 (Beeser et al, 2005) and p38MAPK (Dechert et al, 2001). Towards identifying the downstream signaling molecules in Pak1-mediated retinal neovascularization, here we demonstrate that hypoxia induces p38MAPK phosphorylation in the mouse retina in a Pak1-dependent manner and p38MAPKβ downregulation, by use of its siRNA, results in reduced retinal endothelial cell proliferation, tip cell formation and neovascularization.…”

Section: Discussionmentioning

confidence: 90%

A new role for cofilin in retinal neovascularization

Kumar

Janjanam

Singh

et al. 2016

Journal of Cell Science

View full text Add to dashboard Cite

Pak1 plays an important role in several cellular processes, including cell migration, but its role in pathological angiogenesis is not known. Here, we have determined its role in pathological retinal angiogenesis using an oxygen-induced retinopathy (OIR) model. VEGFA induced phosphorylation of Pak1 and its effector cofilin in a manner that was dependent on time as well as p38MAPKβ (also known as MAPK11) in human retinal microvascular endothelial cells (HRMVECs). Depletion of the levels of any of these molecules inhibited VEGFA-induced HRMVEC F-actin stress fiber formation, migration, proliferation, sprouting and tube formation. In accordance with these observations, hypoxia induced Pak1 and cofilin phosphorylation with p38MAPKβ being downstream to Pak1 and upstream to cofilin in mouse retina. Furthermore, Pak1 deficiency abolished hypoxiainduced p38MAPKβ and cofilin phosphorylation and abrogated retinal endothelial cell proliferation, tip cell formation and neovascularization. In addition, small interfering RNA (siRNA)-mediated downregulation of p38MAPKβ or cofilin levels in the wild-type mouse retina also diminished endothelial cell proliferation, tip cell formation and neovascularization. Taken together, these observations suggest that, although the p38MAPKβ-Pak1-cofilin axis is required for HRMVEC migration, proliferation, sprouting and tubulogenesis, Pak1-p38MAPKβ-cofilin signaling is also essential for hypoxiainduced mouse retinal endothelial cell proliferation, tip cell formation and neovascularization.

show abstract

Role of Group A p21-activated Kinases in Activation of Extracellular-regulated Kinase by Growth Factors

Cited by 121 publications

References 41 publications

Profiling signaling polarity in chemotactic cells

Profiling signaling polarity in chemotactic cells

α6β4 integrin activates Rac-dependent p21-activated kinase 1 to drive NF-κB-dependent resistance to apoptosis in 3D mammary acini

A new role for cofilin in retinal neovascularization

Contact Info

Product

Resources

About