scholarly journals PTEN dephosphorylates Abi1 to promote epithelial morphogenesis

2020 ◽  
Vol 219 (9) ◽  
Author(s):  
Yanmei Qi ◽  
Jie Liu ◽  
Joshua Chao ◽  
Peter A. Greer ◽  
Shaohua Li
Keyword(s):  
Phosphatase Activity ◽  
Pluripotent Stem Cells ◽  
Protein Phosphatase ◽  
Embryoid Bodies ◽  
Epithelial Morphogenesis ◽  
Homologous Protein ◽  
Lipid Phosphatase ◽  
Cytoskeletal Dynamics ◽  
Regulatory Complex ◽  
Actin Cytoskeletal Dynamics

The tumor suppressor PTEN is essential for early development. Its lipid phosphatase activity converts PIP3 to PIP2 and antagonizes the PI3K–Akt pathway. In this study, we demonstrate that PTEN’s protein phosphatase activity is required for epiblast epithelial differentiation and polarization. This is accomplished by reconstitution of PTEN-null embryoid bodies with PTEN mutants that lack only PTEN’s lipid phosphatase activity or both PTEN’s lipid and protein phosphatase activities. Phosphotyrosine antibody immunoprecipitation and mass spectrometry were used to identify Abi1, a core component of the WASP-family verprolin homologous protein (WAVE) regulatory complex (WRC), as a new PTEN substrate. We demonstrate that PTEN dephosphorylation of Abi1 at Y213 and S216 results in Abi1 degradation through the calpain pathway. This leads to down-regulation of the WRC and reorganization of the actin cytoskeleton. The latter is critical to the transformation of nonpolar pluripotent stem cells into the polarized epiblast epithelium. Our findings establish a link between PTEN and WAVE-Arp2/3–regulated actin cytoskeletal dynamics in epithelial morphogenesis.

scholarly journals Functional analysis of the protein phosphatase activity of PTEN

2012 ◽  
Vol 444 (3) ◽  
pp. 457-464 ◽  
Author(s):  
Xiaoqun Catherine Zhang ◽  
Antonella Piccini ◽  
Michael P. Myers ◽  
Linda Van Aelst ◽  
Nicholas K. Tonks
Keyword(s):  
Phosphatase Activity ◽  
Protein Phosphatase ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Tumour Suppressor ◽  
Laser Scanning Microscopy ◽  
Binding Motif ◽  
Spine Density ◽  
Lipid Phosphatase

In vitro, the tumour suppressor PTEN (phosphatase and tensin homologue deleted on chromosome 10) displays intrinsic phosphatase activity towards both protein and lipid substrates. In vivo, the lipid phosphatase activity of PTEN, through which it dephosphorylates the 3 position in the inositol sugar of phosphatidylinositol derivatives, is important for its tumour suppressor function; however, the significance of its protein phosphatase activity remains unclear. Using two-photon laser-scanning microscopy and biolistic gene delivery of GFP (green fluorescent protein)-tagged constructs into organotypic hippocampal slice cultures, we have developed an assay of PTEN function in living tissue. Using this bioassay, we have demonstrated that overexpression of wild-type PTEN led to a decrease in spine density in neurons. Furthermore, it was the protein phosphatase activity, but not the lipid phosphatase activity, of PTEN that was essential for this effect. The ability of PTEN to decrease neuronal spine density depended upon the phosphorylation status of serine and threonine residues in its C-terminal segment and the integrity of the C-terminal PDZ-binding motif. The present study reveals a new aspect of the function of this important tumour suppressor and suggest that, in addition to dephosphorylating the 3 position in phosphatidylinositol phospholipids, the critical protein substrate of PTEN may be PTEN itself.

scholarly journals Analysis of the cellular functions of PTEN using catalytic domain and C-terminal mutations: differential effects of C-terminal deletion on signalling pathways downstream of phosphoinositide 3-kinase

2000 ◽  
Vol 346 (3) ◽  
pp. 827-833 ◽  
Author(s):  
Nick R. LESLIE ◽  
Alex GRAY ◽  
Ian PASS ◽  
Elaine A. ORCHISTON ◽  
C. Peter DOWNES
Keyword(s):  
Cell Viability ◽  
Phosphatase Activity ◽  
Protein Phosphatase ◽  
Hek293 Cells ◽  
Terminal Deletion ◽  
Signalling Pathways ◽  
Detectable Effect ◽  
Binding Motif ◽  
Membrane Ruffling ◽  
Lipid Phosphatase

The tumour suppressor protein, PTEN (phosphatase and tensin homolog deleted on chromosome 10), is a phosphatase that can dephosphorylate tyrosine-containing peptides, Shc, focal adhesion kinase and phosphoinositide substrates. In cellular assays, PTEN has been shown to antagonize the PI-3K-dependent activation of protein kinase B (PKB) and to inhibit cell spreading and motility. It is currently unclear, however, whether PTEN accomplishes these effects through its lipid- or protein-phosphatase activity, although strong evidence has demonstrated the importance of the latter for tumour suppression by PTEN. By using a PTEN G129E (Gly129 → Glu) mutant that has lost its lipid phosphatase activity, while retaining protein phosphatase activity, we demonstrated a requirement for the lipid phosphatase activity of PTEN in the regulation of PKB activity, cell viability and membrane ruffling. We also made a small C-terminal deletion of PTEN, removing a putative PDZ (PSD95, Dlg and ZO1)-binding motif, with no detectable effect on the phosphatase activity of the protein expressed in HEK293 cells (human embryonic kidney 293 cells) assayed in vitro. Surprisingly, expression of this mutant revealed differential requirements for the C-terminus in the different functional assays. Wild-type and C-terminally deleted PTEN appeared to be equally active in down-regulating PKB activity, but this mutant enzyme had no effect on platelet-derived growth factor (PDGF)-induced membrane ruffling and was only partially active in a cell viability assay. These results stress the importance of the lipid phosphatase activity of PTEN in the regulation of several signalling pathways. They also identify a mutation, similar to mutations that occur in some human tumours, which removes the effect of PTEN on membrane ruffling but not that on PKB.

scholarly journals Alpha protocadherins and Pyk2 kinase regulate cortical neuron migration and cytoskeletal dynamics via Rac1 GTPase and WAVE complex in mice

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Li Fan ◽  
Yichao Lu ◽  
Xiulian Shen ◽  
Hong Shao ◽  
Lun Suo ◽  
...  
Keyword(s):  
Cortical Neuron ◽  
Small Gtpase ◽  
Neuron Migration ◽  
Surface Receptors ◽  
Homologous Protein ◽  
Tyrosine Kinase 2 ◽  
Cytoskeletal Dynamics ◽  
Rac1 Gtpase ◽  
Dendrite Morphogenesis ◽  
Actin Cytoskeletal Dynamics

Diverse clustered protocadherins are thought to function in neurite morphogenesis and neuronal connectivity in the brain. Here, we report that the protocadherin alpha (Pcdha) gene cluster regulates neuronal migration during cortical development and cytoskeletal dynamics in primary cortical culture through the WAVE (Wiskott-Aldrich syndrome family verprolin homologous protein, also known as Wasf) complex. In addition, overexpression of proline-rich tyrosine kinase 2 (Pyk2, also known as Ptk2b, Cakβ, Raftk, Fak2, and Cadtk), a non-receptor cell-adhesion kinase and scaffold protein downstream of Pcdhα, impairs cortical neuron migration via inactivation of the small GTPase Rac1. Thus, we define a molecular Pcdhα/WAVE/Pyk2/Rac1 axis from protocadherin cell-surface receptors to actin cytoskeletal dynamics in cortical neuron migration and dendrite morphogenesis in mouse brain.

scholarly journals The localization and activity of sphingosine kinase 1 are coordinately regulated with actin cytoskeletal dynamics in macrophages. VOLUME 282 (2007) PAGES 23147-23162

2008 ◽  
Vol 283 (9) ◽  
pp. 5972
Author(s):  
David J. Kusner ◽  
Christopher R. Thompson ◽  
Natalie A. Melrose ◽  
Stuart M. Pitson ◽  
Lina M. Obeid ◽  
...  
Keyword(s):  
Sphingosine Kinase ◽  
Sphingosine Kinase 1 ◽  
Cytoskeletal Dynamics ◽  
Actin Cytoskeletal Dynamics

scholarly journals Bidirectional feedback between BCR signaling and actin cytoskeletal dynamics

FEBS Journal ◽  
2021 ◽  
Author(s):  
Anshuman Bhanja ◽  
Ivan Rey‐Suarez ◽  
Wenxia Song ◽  
Arpita Upadhyaya
Keyword(s):  
Bcr Signaling ◽  
Cytoskeletal Dynamics ◽  
Actin Cytoskeletal Dynamics

scholarly journals Involvement of a phosphotyrosine protein phosphatase in the suppression of platelet-derived growth factor receptor autophosphorylation in ras-transformed cells

1993 ◽  
Vol 293 (1) ◽  
pp. 215-221 ◽  
Author(s):  
L Tomáska ◽  
R J Resnick
Keyword(s):  
Growth Factor ◽  
Phosphatase Activity ◽  
Receptor Tyrosine Kinase ◽  
Protein Phosphatase ◽  
Kinase Activity ◽  
Platelet Derived Growth Factor ◽  
Transformed Cells ◽  
Pdgf Receptor ◽  
Tyrosine Kinase Activity ◽  
Phosphotyrosine Protein Phosphatase

The nature of the suppression of platelet-derived growth factor (PDGF) receptor autophosphorylation in ras-transformed NIH 3T3 fibroblasts was investigated. The PDGF receptor from ras-transformed cells that had been purified by wheatgerm-lectin affinity chromatography displayed normal PDGF-induced autophosphorylation, indicating that the receptor is not irreversibly modified. Various phosphotyrosine-protein-phosphatase inhibitors did not reverse the inhibition of PDGF-receptor kinase in crude membrane preparations from ras-transformed cells. However, treatment of intact ras-transformed cells both with 2 mM sodium orthovanadate and with 20 microM phenylarsine oxide restored PDGF-receptor tyrosine-kinase activity to a level similar to that observed in normal cells. Direct measurement of the phosphatase activities in crude cellular fractions revealed a 2.5-fold higher membrane-associated phosphotyrosine-protein-phosphatase activity in ras-transformed cells, whereas phosphoserine-protein-phosphatase activity remained unchanged between the cell lines. These data suggest that the suppression of the PDGF-receptor tyrosine-kinase activity in ras-transformed cells is mediated via an inhibitory component, distinct from the receptor, that may be positively regulated by the dephosphorylation of tyrosine residue(s).

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