scholarly journals Identification of ILK as a new partner of the ADAM12 disintegrin and metalloprotease in cell adhesion and survival

2012 ◽  
Vol 23 (17) ◽  
pp. 3461-3472 ◽  
Author(s):  
Anthony Leyme ◽  
Katia Bourd-Boittin ◽  
Dominique Bonnier ◽  
Anaïs Falconer ◽  
Yannick Arlot-Bonnemains ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Focal Adhesions ◽  
Interaction Network ◽  
Integrative Approach ◽  
Β1 Integrin ◽  
Cellular Functions ◽  
Survival Pathway ◽  
Integrin Linked Kinase ◽  
Phosphoinositide 3 Kinase ◽  
Stimulation Of

Based on its shedding and binding activities, the disintegrin and metalloprotease 12 (ADAM12) has been implicated in cell signaling. Here we investigate the intracellular protein interaction network of the transmembrane ADAM12L variant using an integrative approach. We identify the integrin-linked kinase (ILK) as a new partner for ADAM12L cellular functions. We demonstrate that ADAM12L coimmunoprecipitates with ILK in cells and that its cytoplasmic tail is required for this interaction. In human cultured hepatic stellate cells (HSCs), which express high levels of endogenous ADAM12L and ILK, the two proteins are redistributed to focal adhesions upon stimulation of a β1 integrin–dependent pathway. We show that down-regulation of ADAM12L in HSCs leads to cytoskeletal disorganization and loss of adhesion. Conversely, up-regulation of ADAM12L induces the Akt Ser-473 phosphorylation-dependent survival pathway via stimulation of β1 integrins and activation of phosphoinositide 3-kinase (PI3K). Depletion of ILK inhibits this effect, which is independent of ADAM12L proteolytic activity and involves its cytoplasmic domain. We further demonstrate that overexpression of ADAM12L promotes kinase activity from ILK immunoprecipitates. Our data suggest a new role for ADAM12L in mediating the functional association of ILK with β1 integrin to regulate cell adhesion/survival through a PI3K/Akt signaling pathway.

scholarly journals Roles of Gβγ in membrane recruitment and activation of p110γ/p101 phosphoinositide 3-kinase γ

2002 ◽  
Vol 160 (1) ◽  
pp. 89-99 ◽  
Author(s):  
Carsten Brock ◽  
Michael Schaefer ◽  
H. Peter Reusch ◽  
Cornelia Czupalla ◽  
Manuela Michalke ◽  
...  
Keyword(s):  
G Protein ◽  
Living Cells ◽  
Membrane Lipid ◽  
Cellular Functions ◽  
Direct Stimulation ◽  
Membrane Recruitment ◽  
Ph Domains ◽  
Phosphoinositide 3 Kinase ◽  
Stimulation Of

Receptor-regulated class I phosphoinositide 3-kinases (PI3K) phosphorylate the membrane lipid phosphatidylinositol (PtdIns)-4,5-P2 to PtdIns-3,4,5-P3. This, in turn, recruits and activates cytosolic effectors with PtdIns-3,4,5-P3–binding pleckstrin homology (PH) domains, thereby controlling important cellular functions such as proliferation, survival, or chemotaxis. The class IB p110γ/p101 PI3Kγ is activated by Gβγ on stimulation of G protein–coupled receptors. It is currently unknown whether in living cells Gβγ acts as a membrane anchor or an allosteric activator of PI3Kγ, and which role its noncatalytic p101 subunit plays in its activation by Gβγ. Using GFP-tagged PI3Kγ subunits expressed in HEK cells, we show that Gβγ recruits the enzyme from the cytosol to the membrane by interaction with its p101 subunit. Accordingly, p101 was found to be required for G protein–mediated activation of PI3Kγ in living cells, as assessed by use of GFP-tagged PtdIns-3,4,5-P3–binding PH domains. Furthermore, membrane-targeted p110γ displayed basal enzymatic activity, but was further stimulated by Gβγ, even in the absence of p101. Therefore, we conclude that in vivo, Gβγ activates PI3Kγ by a mechanism assigning specific roles for both PI3Kγ subunits, i.e., membrane recruitment is mediated via the noncatalytic p101 subunit, and direct stimulation of Gβγ with p110γ contributes to activation of PI3Kγ.

scholarly journals Integrin-linked kinase tunes cell-cell and cell-matrix adhesions to regulate the switch between apoptosis and EMT downstream of TGFβ1

2021 ◽  
pp. mbc.E20-02-0092
Author(s):  
Ayse Nihan Kilinc ◽  
Siyang Han ◽  
Lena Barrett ◽  
Niroshan Anandasivam ◽  
Celeste M. Nelson
Keyword(s):  
Cell Adhesion ◽  
Epithelial Cells ◽  
Focal Adhesions ◽  
Cell Phenotype ◽  
High Cell ◽  
Potent Inducer ◽  
Mesenchymal Transition ◽  
Cell Matrix ◽  
Integrin Linked Kinase ◽  
Cell Cell

Epithelial-mesenchymal transition (EMT) is a morphogenetic process that endows epithelial cells with migratory and invasive potential. Mechanical and chemical signals from the tumor microenvironment can activate the EMT program, thereby permitting cancer cells to invade the surrounding stroma and disseminate to distant organs. Transforming growth factor β1 (TGFβ1) is a potent inducer of EMT that can also induce apoptosis depending on the microenvironmental context. In particular, stiff microenvironments promote EMT while softer ones promote apoptosis. Here, we investigated the molecular signaling downstream of matrix stiffness that regulates the phenotypic switch in response to TGFβ1, and uncovered a critical role for integrin-linked kinase (ILK). Specifically, depleting ILK from mammary epithelial cells precludes their ability to sense the stiffness of their microenvironment. In response to treatment with TGFβ1, ILK-depleted cells undergo apoptosis on both soft and stiff substrata. We found that knockdown of ILK decreases focal adhesions and increases cell-cell adhesions, thus shifting the balance from cell-matrix to cell-cell adhesion. High cell-matrix adhesion promotes EMT whereas high cell-cell adhesion promotes apoptosis downstream of TGFβ1. These results highlight an important role for ILK in controlling cell phenotype by regulating adhesive connections to the local microenvironment.

scholarly journals Substratum stiffness signals through integrin-linked kinase and β1-integrin to regulate midbody proteins and abscission during EMT

2021 ◽  
pp. mbc.E21-02-0072
Author(s):  
Emann M. Rabie ◽  
Sherry X. Zhang ◽  
Connor E. Dunn ◽  
Celeste M. Nelson
Keyword(s):  
Cellular Response ◽  
Focal Adhesions ◽  
Tissue Mechanics ◽  
Normal Mammary Gland ◽  
Parent Cell ◽  
Β1 Integrin ◽  
Neoplastic Progression ◽  
Mesenchymal Transition ◽  
Integrin Linked Kinase ◽  
In Cells

Abscission is the final stage of cytokinesis during which the parent cell physically separates to yield two identical daughters. Failure of abscission results in multinucleation, a sign of genomic instability and a precursor to aneuploidy, enabling characteristics of neoplastic progression. Induction of epithelial-mesenchymal transition (EMT) causes multinucleation in mammary epithelial cells cultured on stiff microenvironments that have mechanical properties similar to those found in breast tumors, but not on soft microenvironments reminiscent of the normal mammary gland. Here, we report that on stiff microenvironments, EMT signaling through Snail upregulates the midbody-associated proteins septin-6, Mklp1, and anillin, leading to abscission failure and multinucleation. To uncover the mechanism by which stiff microenvironments promote multinucleation in cells undergoing EMT, we investigated the role of cell-matrix adhesion through β1-integrin and integrin-linked kinase (ILK). We found that ILK expression, but not kinase activity, is required for EMT-associated multinucleation in cells on stiff microenvironments. Conversely, increasing focal adhesions by expressing an autoclustering β1-integrin promotes multinucleation in cells on soft microenvironments. Our data suggest that signaling through focal adhesions causes failure of cytokinesis in cells actively undergoing EMT. These results highlight the importance of tissue mechanics and adhesion in regulating the cellular response to EMT inducers.

scholarly journals Integrin Linked Kinase (ILK) and its Role in Liver Pathobiology

2021 ◽  
Author(s):  
Nicole J. Martucci ◽  
George K. Michalopoulos ◽  
Wendy M. Mars
Keyword(s):  
Hepatocellular Carcinoma ◽  
Insulin Resistance ◽  
Cell Adhesion ◽  
Liver Regeneration ◽  
The Body ◽  
Cellular Functions ◽  
Signaling Protein ◽  
Integrin Linked Kinase

Integrin Linked Kinase is a vital signaling protein ubiquitously expressed throughout the body. It binds to intracellular integrins to help promote signaling related to cell adhesion, apoptosis, proliferation, migration, and a plethora of other common cellular functions. In this review, ILK’s role in the liver is detailed. Studies have shown ILK to be a major participant in hepatic ECM organization, liver regeneration, insulin resistance, and hepatocellular carcinoma.

scholarly journals Microtubules tune mechanosensitive cell responses

2020 ◽  
Author(s):  
Shailaja Seetharaman ◽  
Benoit Vianay ◽  
Vanessa Roca ◽  
Chiara De Pascalis ◽  
Batiste Boëda ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Focal Adhesions ◽  
Post Translational Modification ◽  
Cellular Functions ◽  
Alpha Tubulin ◽  
Cell Responses ◽  
Surrounding Environment ◽  
Substrate Rigidity ◽  
Cell Adhesion And Migration ◽  
And Migration

AbstractMechanotransduction is a process by which cells sense the mechanical properties of their surrounding environment and adapt accordingly to perform cellular functions such as adhesion, migration and differentiation. Integrin-mediated focal adhesions are major sites of mechanotransduction and their connection with the actomyosin network is crucial for mechanosensing as well as the generation and transmission of forces onto the substrate. Despite having emerged as major regulators of cell adhesion and migration, the contribution of microtubules to mechanotransduction still remains elusive. Here, we show that actomyosin-dependent mechanosensing of substrate rigidity controls microtubule acetylation, a tubulin post-translational modification, by promoting the recruitment of the alpha-tubulin acetyl transferase (αTAT1) to focal adhesions. Microtubule acetylation, in turn, promotes GEF-H1 mediated RhoA activation, actomyosin contractility and traction forces. Our results reveal a fundamental crosstalk between microtubules and actin in mechanotransduction, which contributes to mechanosensitive cell adhesion and migration.

Differences in phosphatase modulation of α4 β1 and α5 β1 integrin-mediated adhesion and migration of B16F1 cells

1999 ◽  
Vol 77 (5) ◽  
pp. 409-420 ◽  
Author(s):  
Dolores Hangan-Steinman ◽  
Wai-chi Ho ◽  
Priti Shenoy ◽  
Bosco MC Chan ◽  
Vincent L Morris
Keyword(s):  
Cell Adhesion ◽  
Adhesive Strength ◽  
Cell Movement ◽  
Protein Tyrosine Phosphatases ◽  
Β1 Integrin ◽  
Phosphatase Inhibitors ◽  
Β1 Integrins ◽  
Cell Adhesion And Migration ◽  
And Migration ◽  
B16f1 Cell

It is well established that a biphasic relationship exists between the adhesive strength of β1 integrins and their ability to mediate cell movement. Thus, cell movement increases progressively with adhesive strength, but beyond a certain point of optimal interaction, cell movement is reduced with further increases in adhesive function. The interplay between the various kinase and phosphatase activities provides the balance in β1 integrin-mediated cell adhesion and migration. In the present study, the significance of protein tyrosine phosphatases (PTP) and ser/thr protein phosphatases (PP) in α4β1 and α5β1 integrin-mediated mouse melanoma B16F1 cell anchorage and migration on fibronectin was characterized using phosphatase inhibitors. At low fibronectin concentration, α5β1 functioned as the predominant receptor for cell movement; a role for α4β1 in B16F1 cell migration increased progressively with fibronectin concentration. Treatment of B16F1 cells with PTP inhibitors, sodium orthovanadate (Na3VO4) and phenylarsine oxide (PAO), or PP-1/2A inhibitor, okadaic acid (OA), abolished cell movement. Inhibition of cell movement by PAO and OA was associated by a reduction in the adhesive strength of α4β1 and α5β1. In contrast, treatment of B16F1 cells with Na3VO4 resulted in selective stimulation of the adhesive function of α5β1, but not α4β1. Therefore, our results demonstrate that (i) both PTP and PP-1/2A have roles in cell movement, (ii) modulation of cell movement by PTP and PP-1/2A may involve either a stimulation or reduction of β1 integrin adhesive strength, and (iii) distinct phosphatase-mediated signaling pathways for differential regulation of the various β1 integrins exist. Key words: phosphatases, integrins, cell movement, cell adhesion.

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