The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Shoukat Dedhar - One of the best experts on this subject based on the ideXlab platform.

  • Integrin Linked Kinase mediates therapeutic resistance of quiescent cml stem cells to tyrosine Kinase inhibitors
    Cell Stem Cell, 2020
    Co-Authors: Katharina Rothe, Artem Babaian, Naoto Nakamichi, Min Chen, Shawn C Chafe, Akie Watanabe, Donna L Forrest, Dixie L Mager, Connie J Eaves, Shoukat Dedhar
    Abstract:

    Summary Patients with chronic myeloid leukemia (CML) often require lifelong therapy with ABL1 tyrosine Kinase inhibitors (TKIs) due to a persisting TKI-resistant population of leukemic stem cells (LSCs). From transcriptome profiling, we show Integrin-Linked Kinase (ILK), a key constituent of focal adhesions, is highly expressed in TKI-nonresponsive patient cells and their LSCs. Genetic and pharmacological inhibition of ILK impaired the survival of nonresponder patient cells, sensitizing them to TKIs, even in the presence of protective niche cells. Furthermore, ILK inhibition eliminated TKI-refractory LSCs from patients, but not normal HSCs, in vitro and in vivo. RNA-sequencing and functional validation studies implicated an important role of ILK in maintaining a requisite level of mitochondrial oxidative metabolism in highly purified, quiescent LSCs. Thus, these findings point to ILK as a critical survival mediator to TKIs and quiescent stem cells, offering an attractive therapeutic target and model for curative combination therapies in stem-cell-driven cancers.

  • Development/Plasticity/Repair Integrin-Linked Kinase Deletion fromMouse Cortex Results in Cortical Lamination Defects Resembling Cobblestone Lissencephaly
    2016
    Co-Authors: Agnieszka Niewmierzycka, Shoukat Dedhar, Julia Mills, Rene St-arnaud, Louis F. Reichardt
    Abstract:

    Integrin-Linked Kinase (Ilk) is a scaffold and Kinase that links Integrin receptors to the actin cytoskeleton and to signaling pathways involved in cell adhesion, migration, and extracellular matrix deposition. Targeted deletion of Ilk from embryonic mouse dorsal fore-brain neuroepithelium results in severe cortical lamination defects resembling cobblestone (type II) lissencephaly. Defects in adult mutants include neuronal invasion of the marginal zone, downward displacement of marginal zone components, fusion of the cerebral hemispheres, and scalloping of the dentate gyrus. These lesions are associatedwith abundant astrogliosis andwidespread fragmentation of the basal lamina at the cortical surface. During cortical development, neuronal ectopias are associated with severe disorganization of radial glial processes and displacement of Cajal-Retzius cells. Lesions are not seen when Ilk is specifically deleted from embryonic neurons. Interestingly, targeted Ilk deletion has no effect on proliferation or survival of cortical cells or on phosphorylation of two Ilk substrates, Pkb/Akt and Gsk-3, suggesting that Ilk does not regulate cortical lamination via these enzymes. Instead, Ilk acts in vivo as a major intracellular mediator of Integrin-dependent basal lamina formation. This study demonstrates a critical role for Ilk in cortical lamination and suggests that Ilk-associated pathways are involved in the pathogenesis of cobblestone lissencephalies. Key words: Integrin-Linked Kinase; extracellular matrix; cortical development; cobblestone lissencephaly; radial glia; reeli

  • inactivation of the hippo tumour suppressor pathway by Integrin Linked Kinase
    Nature Communications, 2013
    Co-Authors: Isabel Serrano, William J Muller, Frances E Lock, Paul C Mcdonald, Shoukat Dedhar
    Abstract:

    One of the hallmarks of cancers is the silencing of tumour suppressor genes and pathways. The Hippo tumour suppressor pathway is inactivated in many types of cancers, leading to tumour progression and metastasis. However, the mechanisms of pathway inactivation in tumours remain unclear. Here we demonstrate that Integrin-Linked Kinase (ILK) plays a critical role in the suppression of the Hippo pathway via phospho-inhibition of MYPT1-PP1, leading to inactivation of Merlin. Inhibition of ILK in breast, prostate and colon tumour cells results in the activation of the Hippo pathway components MST1 and LATS1 with concomitant inactivation of YAP/TAZ (Yes-associated protein/transcriptional co-activator with PDZ-binding motif) transcriptional co-activators and TEAD-mediated transcription. Genetic deletion of ILK suppresses ErbB2-driven YAP/TAZ activation in mammary tumours, and its pharmacological inhibition suppresses YAP activation and tumour growth in vivo. Our data demonstrate a role for ILK as a multiple receptor proximal regulator of Hippo tumour suppressor pathway and as a cancer therapeutic target.

  • the importance of Integrin Linked Kinase in the regulation of bladder cancer invasion
    International Journal of Cancer, 2012
    Co-Authors: Yoshiyuki Matsui, Shoukat Dedhar, Martin E Gleave, Kiran Assi, Osamu Ogawa, Peter A Raven, Baljinder Salh
    Abstract:

    It is important to understand the molecular mechanisms of bladder cancer progression not only to prevent cancer progression but also to detect new therapeutic targets against advanced bladder cancer. The Integrin-Linked Kinase (ILK) is a major signaling integrator in mammalian cells and plays an important role in epithelial–mesenchymal transition (EMT) of human cancers, but its mechanisms are not completely understood. In this study, we investigated the importance and mechanisms of ILK in bladder cancer progression. When the expression of ILK in bladder cancer cell lines and N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN)-induced murine bladder cancer was evaluated, ILK has a tendency to be overexpressed in invasive cell lines and invasive BBN-induced murine bladder cancer. Overexpression of ILK in 253J bladder cancer cells suppressed E-cadherin expression, resulting in the promotion of cell invasion. Conversely, ILK knockdown by siRNA suppresses cell invasion in invasive bladder cancer cells through the regulation of E-cadherin or matrix metalloprotease 9 (MMP-9). To regulate E-cadherin expression, our results showed that the glycogen synthase Kinase 3β (GSK3β)-Zeb1 pathway may play an important role downstream of ILK. Finally, the results of a human bladder tissue microarray (TMA) showed that ILK expression correlates with the invasiveness of human bladder cancer. Our study suggests that ILK is overexpressed in invasive bladder cancer and plays an important role in the EMT of bladder cancer via the control of E-cadherin and MMP-9 expression. ILK may be a new molecular target to suppress tumor progression in advanced and high-risk bladder cancer patients.

  • cooperative signaling between wnt1 and Integrin Linked Kinase induces accelerated breast tumor development
    Breast Cancer Research, 2010
    Co-Authors: Arusha Oloumi, Mykola Maidan, Frances E Lock, Howard Tearle, Steven Mckinney, William J Muller, Samuel Aparicio, Shoukat Dedhar
    Abstract:

    Introduction Breast cancer is genetically and clinically a heterogeneous disease. However, the exact contribution of different cell types and oncogenic mutations to this heterogeneity are not well understood. Recently, we discovered an interaction between Wnt and Integrin-Linked Kinase (ILK) within the signaling cascade that regulates cell growth and survival. Interestingly, mammary-specific expression of either one of these proteins has been shown to promote mammary tumorigenesis. In light of our recent findings and to investigate the potential interaction between Wnt and ILK proteins during mammary tumor formation and progression, we established a transgenic mouse model that expresses both Wnt and ILK in mammary epithelial cells.

Sven Hammerschmidt - One of the best experts on this subject based on the ideXlab platform.

  • Integrin Linked Kinase is required for vitronectin mediated internalization of streptococcus pneumoniae by host cells
    Journal of Cell Science, 2009
    Co-Authors: Simone Bergmann, Anke Lang, Claudia Rennemeier, Vaibhav Agarwal, Carsten Grashoff, Manfred Rohde, Klaus T Preissner, Sven Hammerschmidt
    Abstract:

    By interacting with components of the human host, including extracellular matrix (ECM) proteins, Streptococcus pneumoniae has evolved various strategies for colonization. Here, we characterized the interaction of pneumococci with the adhesive glycoprotein vitronectin and the contribution of this protein to pneumococcal uptake by host cells in an Integrin-dependent manner. Specific interaction of S. pneumoniae with the heparin-binding sites of purified multimeric vitronectin was demonstrated by flow cytometry analysis. Host-cell-bound vitronectin promoted pneumococcal adherence to and invasion into human epithelial and endothelial cells. Pneumococci were trapped by microspike-like structures, which were induced upon contact of pneumococci with host-cell-bound vitronectin. αvβ3 Integrin was identified as the major cellular receptor for vitronectin-mediated adherence and uptake of pneumococci. Ingestion of pneumococci by host cells via vitronectin required a dynamic actin cytoskeleton and was dependent on Integrin-Linked Kinase (ILK), phosphatidylinositol 3-Kinase (PI3K), and protein Kinase B (Akt), as demonstrated by gene silencing or in inhibition experiments. In conclusion, pneumococci exploit the vitronectin–αvβ3-Integrin complex as a cellular receptor for invasion and this Integrin-mediated internalization requires the cooperation between the host signalling molecules ILK, PI3K and Akt.

  • Integrin Linked Kinase is required for vitronectin mediated internalization of streptococcus pneumoniae by host cells
    Journal of Cell Science, 2009
    Co-Authors: Simone Bergmann, Anke Lang, Claudia Rennemeier, Vaibhav Agarwal, Carsten Grashoff, Sven Hammerschmidt, Manfred Rohde, Klaus T Preissner
    Abstract:

    By interacting with components of the human host, including extracellular matrix (ECM) proteins, Streptococcus pneumoniae has evolved various strategies for colonization. Here, we characterized the interaction of pneumococci with the adhesive glycoprotein vitronectin and the contribution of this protein to pneumococcal uptake by host cells in an Integrin-dependent manner. Specific interaction of S. pneumoniae with the heparin-binding sites of purified multimeric vitronectin was demonstrated by flow cytometry analysis. Host-cell-bound vitronectin promoted pneumococcal adherence to and invasion into human epithelial and endothelial cells. Pneumococci were trapped by microspike-like structures, which were induced upon contact of pneumococci with host-cell-bound vitronectin. Alphavbeta3 Integrin was identified as the major cellular receptor for vitronectin-mediated adherence and uptake of pneumococci. Ingestion of pneumococci by host cells via vitronectin required a dynamic actin cytoskeleton and was dependent on Integrin-Linked Kinase (ILK), phosphatidylinositol 3-Kinase (PI3K), and protein Kinase B (Akt), as demonstrated by gene silencing or in inhibition experiments. In conclusion, pneumococci exploit the vitronectin-alphavbeta3-Integrin complex as a cellular receptor for invasion and this Integrin-mediated internalization requires the cooperation between the host signalling molecules ILK, PI3K and Akt.

Carsten Grashoff - One of the best experts on this subject based on the ideXlab platform.

  • the role of Integrin Linked Kinase in the molecular architecture of focal adhesions
    Journal of Cell Science, 2013
    Co-Authors: Nadav Elad, Carsten Grashoff, Reinhard Fässler, Joachim P Spatz, Tova Volberg, Israel Patla, Vera C Hirschfeldwarneken, Benjamin Geiger
    Abstract:

    Integrin-mediated focal adhesions (FAs) are large, multi-protein complexes that link the actin cytoskeleton to the extracellular matrix and take part in adhesion-mediated signaling. These adhesions are highly complex and diverse at the molecular level; thus, assigning particular structural or signaling functions to specific components is highly challenging. Here, we combined functional, structural and biophysical approaches to assess the role of a major FA component, namely, Integrin-Linked Kinase (ILK), in adhesion formation. We show here that ILK plays a key role in the formation of focal complexes, early forms of Integrin adhesions, and confirm its involvement in the assembly of fibronectin-bound fibrillar adhesions. Examination of ILK-null fibroblasts by cryo-electron tomography pointed to major structural changes in their FAs, manifested as disarray of the associated actin filaments and an increase in the packing density of FA-related particles. Interestingly, adhesion of the mutant cells to the substrate required a higher ligand density than in control cells. These data indicate that ILK has a key role in Integrin adhesion assembly and sub-structure, and in the regulation of the FA-associated cytoskeleton.

  • mutations in the paxillin binding site of Integrin Linked Kinase ilk destabilize the pseudoKinase domain and cause embryonic lethality in mice
    Journal of Biological Chemistry, 2013
    Co-Authors: Daniel Moik, Carsten Grashoff, Nada Bulus, Roy Zent, Anika Bottcher, Tatiana Makhina, Reinhard Fässler
    Abstract:

    Integrin-Linked Kinase (ILK) localizes to focal adhesions (FAs) where it regulates cell spreading, migration, and growth factor receptor signaling. Previous reports showed that overexpressed ILK in which Val386 and Thr387 were substituted with glycine residues (ILK-VT/GG) could neither interact with paxillin nor localize to FA in cells expressing endogenous wild-type ILK, implying that paxillin binding to ILK is required for its localization to FAs. Here, we show that introducing this mutation into the germ line of mice (ILK-VT/GG) caused vasculogenesis defects, resulting in a general developmental delay and death at around embryonic day 12.5. Fibroblasts isolated from ILK-VT/GG mice contained mutant ILK in FAs, showed normal adhesion to and spreading on extracellular matrix substrates but displayed impaired migration. Biochemical analysis revealed that VT/GG substitutions decreased ILK protein stability leading to decreased ILK levels and reduced binding to paxillin and α-parvin. Because paxillin depletion did not affect ILK localization to FAs, the embryonic lethality and the in vitro migration defects are likely due to the reduced levels of ILK-VT/GG and diminished binding to parvins. Background: Integrin-Linked Kinase is believed to be recruited to focal adhesions (FAs) by binding paxillin via a conserved motif in the pseudoKinase domain. Results: The paxillin-binding motif is not required for FA localization but for ILK stability, parvin and paxillin binding, and mouse development. Conclusion: ILK does not require paxillin for FA localization. Significance: Reducing ILK stability perturbs cell migration and development.

  • Integrin Linked Kinase is required for vitronectin mediated internalization of streptococcus pneumoniae by host cells
    Journal of Cell Science, 2009
    Co-Authors: Simone Bergmann, Anke Lang, Claudia Rennemeier, Vaibhav Agarwal, Carsten Grashoff, Manfred Rohde, Klaus T Preissner, Sven Hammerschmidt
    Abstract:

    By interacting with components of the human host, including extracellular matrix (ECM) proteins, Streptococcus pneumoniae has evolved various strategies for colonization. Here, we characterized the interaction of pneumococci with the adhesive glycoprotein vitronectin and the contribution of this protein to pneumococcal uptake by host cells in an Integrin-dependent manner. Specific interaction of S. pneumoniae with the heparin-binding sites of purified multimeric vitronectin was demonstrated by flow cytometry analysis. Host-cell-bound vitronectin promoted pneumococcal adherence to and invasion into human epithelial and endothelial cells. Pneumococci were trapped by microspike-like structures, which were induced upon contact of pneumococci with host-cell-bound vitronectin. αvβ3 Integrin was identified as the major cellular receptor for vitronectin-mediated adherence and uptake of pneumococci. Ingestion of pneumococci by host cells via vitronectin required a dynamic actin cytoskeleton and was dependent on Integrin-Linked Kinase (ILK), phosphatidylinositol 3-Kinase (PI3K), and protein Kinase B (Akt), as demonstrated by gene silencing or in inhibition experiments. In conclusion, pneumococci exploit the vitronectin–αvβ3-Integrin complex as a cellular receptor for invasion and this Integrin-mediated internalization requires the cooperation between the host signalling molecules ILK, PI3K and Akt.

  • Integrin Linked Kinase is required for vitronectin mediated internalization of streptococcus pneumoniae by host cells
    Journal of Cell Science, 2009
    Co-Authors: Simone Bergmann, Anke Lang, Claudia Rennemeier, Vaibhav Agarwal, Carsten Grashoff, Sven Hammerschmidt, Manfred Rohde, Klaus T Preissner
    Abstract:

    By interacting with components of the human host, including extracellular matrix (ECM) proteins, Streptococcus pneumoniae has evolved various strategies for colonization. Here, we characterized the interaction of pneumococci with the adhesive glycoprotein vitronectin and the contribution of this protein to pneumococcal uptake by host cells in an Integrin-dependent manner. Specific interaction of S. pneumoniae with the heparin-binding sites of purified multimeric vitronectin was demonstrated by flow cytometry analysis. Host-cell-bound vitronectin promoted pneumococcal adherence to and invasion into human epithelial and endothelial cells. Pneumococci were trapped by microspike-like structures, which were induced upon contact of pneumococci with host-cell-bound vitronectin. Alphavbeta3 Integrin was identified as the major cellular receptor for vitronectin-mediated adherence and uptake of pneumococci. Ingestion of pneumococci by host cells via vitronectin required a dynamic actin cytoskeleton and was dependent on Integrin-Linked Kinase (ILK), phosphatidylinositol 3-Kinase (PI3K), and protein Kinase B (Akt), as demonstrated by gene silencing or in inhibition experiments. In conclusion, pneumococci exploit the vitronectin-alphavbeta3-Integrin complex as a cellular receptor for invasion and this Integrin-mediated internalization requires the cooperation between the host signalling molecules ILK, PI3K and Akt.

  • tenascin c induction by cyclic strain requires Integrin Linked Kinase
    Biochimica et Biophysica Acta, 2008
    Co-Authors: Silke Maier, Carsten Grashoff, Roman Lutz, Laurent Gelman, Ana Sarasarenedo, Susanne Schenk, Matthias Chiquet
    Abstract:

    Induction of tenascin-C mRNA by cyclic strain in fibroblasts depends on RhoA and Rho dependent Kinase (ROCK). Here we show that Integrin-Linked Kinase (ILK) is required upstream of this pathway. In ILK-deficient fibroblasts, RhoA was not activated and tenascin-C mRNA remained low after cyclic strain; tenascin-C expression was unaffected by ROCK inhibition. In ILK wild-type but not ILK −/− fibroblasts, cyclic strain-induced reorganization of actin stress fibers and focal adhesions, as well as nuclear translocation of MAL, a transcriptional co-activator that links actin assembly to gene expression. These findings support a role for RhoA in ILK-mediated mechanotransduction. Rescue of ILK −/− fibroblasts by expression of wild-type ILK restored these responses to cyclic strain. Mechanosensation is not entirely abolished in ILK −/− fibroblasts, since cyclic strain activated Erk-1/2 and PKB/Akt, and induced c-fos mRNA in these cells. Conversely, lysophosphatidic acid stimulated RhoA and induced both c-fos and tenascin-C mRNA in ILK −/− cells. Thus, the signaling pathways controlling tenascin-C expression are functional in the absence of ILK, but are not triggered by cyclic strain. Our results indicate that ILK is selectively required for the induction of specific genes by mechanical stimulation via RhoA-mediated pathways.

Reinhard Fässler - One of the best experts on this subject based on the ideXlab platform.

  • the role of Integrin Linked Kinase in the molecular architecture of focal adhesions
    Journal of Cell Science, 2013
    Co-Authors: Nadav Elad, Carsten Grashoff, Reinhard Fässler, Joachim P Spatz, Tova Volberg, Israel Patla, Vera C Hirschfeldwarneken, Benjamin Geiger
    Abstract:

    Integrin-mediated focal adhesions (FAs) are large, multi-protein complexes that link the actin cytoskeleton to the extracellular matrix and take part in adhesion-mediated signaling. These adhesions are highly complex and diverse at the molecular level; thus, assigning particular structural or signaling functions to specific components is highly challenging. Here, we combined functional, structural and biophysical approaches to assess the role of a major FA component, namely, Integrin-Linked Kinase (ILK), in adhesion formation. We show here that ILK plays a key role in the formation of focal complexes, early forms of Integrin adhesions, and confirm its involvement in the assembly of fibronectin-bound fibrillar adhesions. Examination of ILK-null fibroblasts by cryo-electron tomography pointed to major structural changes in their FAs, manifested as disarray of the associated actin filaments and an increase in the packing density of FA-related particles. Interestingly, adhesion of the mutant cells to the substrate required a higher ligand density than in control cells. These data indicate that ILK has a key role in Integrin adhesion assembly and sub-structure, and in the regulation of the FA-associated cytoskeleton.

  • mutations in the paxillin binding site of Integrin Linked Kinase ilk destabilize the pseudoKinase domain and cause embryonic lethality in mice
    Journal of Biological Chemistry, 2013
    Co-Authors: Daniel Moik, Carsten Grashoff, Nada Bulus, Roy Zent, Anika Bottcher, Tatiana Makhina, Reinhard Fässler
    Abstract:

    Integrin-Linked Kinase (ILK) localizes to focal adhesions (FAs) where it regulates cell spreading, migration, and growth factor receptor signaling. Previous reports showed that overexpressed ILK in which Val386 and Thr387 were substituted with glycine residues (ILK-VT/GG) could neither interact with paxillin nor localize to FA in cells expressing endogenous wild-type ILK, implying that paxillin binding to ILK is required for its localization to FAs. Here, we show that introducing this mutation into the germ line of mice (ILK-VT/GG) caused vasculogenesis defects, resulting in a general developmental delay and death at around embryonic day 12.5. Fibroblasts isolated from ILK-VT/GG mice contained mutant ILK in FAs, showed normal adhesion to and spreading on extracellular matrix substrates but displayed impaired migration. Biochemical analysis revealed that VT/GG substitutions decreased ILK protein stability leading to decreased ILK levels and reduced binding to paxillin and α-parvin. Because paxillin depletion did not affect ILK localization to FAs, the embryonic lethality and the in vitro migration defects are likely due to the reduced levels of ILK-VT/GG and diminished binding to parvins. Background: Integrin-Linked Kinase is believed to be recruited to focal adhesions (FAs) by binding paxillin via a conserved motif in the pseudoKinase domain. Results: The paxillin-binding motif is not required for FA localization but for ILK stability, parvin and paxillin binding, and mouse development. Conclusion: ILK does not require paxillin for FA localization. Significance: Reducing ILK stability perturbs cell migration and development.

  • stabilization of Integrin Linked Kinase by the hsp90 chip axis impacts cellular force generation migration and the fibrotic response
    The EMBO Journal, 2013
    Co-Authors: Korana Radovanac, Thomas Krieg, Jessica Morgner, Matthias Mann, Jan Niklas Schulz, Katrin Blumbach, Cam Patterson, Tamar Geiger, Beate Eckes, Reinhard Fässler
    Abstract:

    Integrin-Linked Kinase (ILK) is an adaptor protein required to establish and maintain the connection between Integrins and the actin cytoskeleton. This linkage is essential for generating force between the extracellular matrix (ECM) and the cell during migration and matrix remodelling. The mechanisms by which ILK stability and turnover are regulated are unknown. Here we report that the E3 ligase CHIP–heat shock protein 90 (Hsp90) axis regulates ILK turnover in fibroblasts. The chaperone Hsp90 stabilizes ILK and facilitates the interaction of ILK with α-parvin. When Hsp90 activity is blocked, ILK is ubiquitinated by CHIP and degraded by the proteasome, resulting in impaired fibroblast migration and a dramatic reduction in the fibrotic response to bleomycin in mice. Together, our results uncover how Hsp90 regulates ILK stability and identify a potential therapeutic strategy to alleviate fibrotic diseases.

  • Integrin-Linked Kinase regulates p38 MAPK-dependent cell cycle arrest in ureteric bud development.
    Development (Cambridge England), 2010
    Co-Authors: Joanna Smeeton, Thomas J. Carroll, Xi Zhang, Nada Bulus, Glenda Mernaugh, Anika Lange, Courtney M. Karner, Reinhard Fässler, Ambra Pozzi, Norman D. Rosenblum
    Abstract:

    The Integrin-Linked Kinase (ILK), pinch and parvin ternary complex connects the cytoplasmic tails of beta1 Integrins to the actin cytoskeleton. We recently showed that constitutive expression of ILK and alpha parvin in both the ureteric bud and the metanephric mesenchyme of the kidney is required for kidney development. In this study, we define the selective role of ILK in the ureteric bud of the mouse kidney in renal development by deleting it in the ureteric cell lineage before the onset of branching morphogenesis (E10.5). Although deleting ILK resulted in only a moderate decrease in branching, the mice died at 8 weeks of age from obstruction due to the unprecedented finding of intraluminal collecting duct cellular proliferation. ILK deletion in the ureteric bud resulted in the inability of collecting duct cells to undergo contact inhibition and to activate p38 mitogen-activated protein Kinase (MAPK) in vivo and in vitro. p38 MAPK activation was not dependent on the Kinase activity of ILK. Thus, we conclude that ILK plays a crucial role in activating p38 MAPK, which regulates cell cycle arrest of epithelial cells in renal tubulogenesis.

  • Integrin Linked Kinase is an adaptor with essential functions during mouse development
    Nature, 2009
    Co-Authors: Anika Lange, Sara A Wickstrom, Madis Jakobson, Roy Zent, Kirsi Sainio, Reinhard Fässler
    Abstract:

    The development of multicellular organisms requires Integrin-mediated interactions between cells and their extracellular environment. Integrin binding to extracellular matrix catalyses assembly of multiprotein complexes, which transduce mechanical and chemical signals that regulate many aspects of cell physiology. Integrin-Linked Kinase (Ilk) is a multifunctional protein that binds beta-Integrin cytoplasmic domains and regulates actin dynamics by recruiting actin binding regulatory proteins such as alpha- and beta-parvin. Ilk has also been shown to possess serine/threonine Kinase activity and to phosphorylate signalling proteins such as Akt1 and glycogen synthase Kinase 3beta (Gsk3beta) in mammalian cells; however, these functions have been shown by genetic studies not to occur in flies and worms. Here we show that mice carrying point mutations in the proposed autophosphorylation site of the putative Kinase domain and in the pleckstrin homology domain are normal. In contrast, mice with point mutations in the conserved lysine residue of the potential ATP-binding site of the Kinase domain, which mediates Ilk binding to alpha-parvin, die owing to renal agenesis. Similar renal defects occur in alpha-parvin-null mice. Thus, we provide genetic evidence that the Kinase activity of Ilk is dispensable for mammalian development; however, an interaction between Ilk and alpha-parvin is critical for kidney development.

Youhua Liu - One of the best experts on this subject based on the ideXlab platform.

  • inhibition of Integrin Linked Kinase blocks podocyte epithelial mesenchymal transition and ameliorates proteinuria
    Kidney International, 2010
    Co-Authors: Young Sun Kang, Chunsun Dai, Lawrence P Kiss, Youhua Liu
    Abstract:

    Proteinuria is a primary clinical symptom of a large number of glomerular diseases that progress to end-stage renal failure. Podocyte dysfunctions play a fundamental role in defective glomerular filtration in many common forms of proteinuric kidney disorders. Since binding of these cells to the basement membrane is mediated by Integrins, we determined the role of Integrin-Linked Kinase (ILK) in podocyte dysfunction and proteinuria. ILK expression was induced in mouse podocytes by various injurious stimuli known to cause proteinuria including TGF-β1, adriamycin, puromycin, and high ambient glucose. Podocyte ILK was also found to be upregulated in human proteinuric glomerular diseases. Ectopic expression of ILK in podocytes decreased levels of the epithelial markers nephrin and ZO-1, induced mesenchymal markers such as desmin, fibronectin, matrix metalloproteinase-9 (MMP-9), and α-smooth muscle actin (α-SMA), promoted cell migration, and increased the paracellular albumin flux across podocyte monolayers. ILK also induced Snail, a key transcription factor mediating epithelial–mesenchymal transition (EMT). Blockade of ILK activity with a highly selective small molecule inhibitor reduced Snail induction and preserved podocyte phenotypes following TGF-β1 or adriamycin stimulation. In vivo , this ILK inhibitor ameliorated albuminuria, repressed glomerular induction of MMP-9 and α-SMA, and preserved nephrin expression in murine adriamycin nephropathy. Our results show that upregulation of ILK is a convergent pathway leading to podocyte EMT, migration, and dysfunction. ILK may be an attractive target for therapeutic intervention of proteinuric kidney diseases.

  • inhibition of Integrin Linked Kinase attenuates renal interstitial fibrosis
    Journal of The American Society of Nephrology, 2009
    Co-Authors: Xiaoyue Tan, Chunsun Dai, Donna B Stolz, Dan Wang, Youhua Liu
    Abstract:

    Integrin-Linked Kinase (ILK) is an intracellular serine/threonine protein Kinase that regulates cell adhesion, survival, and epithelial-to-mesenchymal transition (EMT). In this study, we investigated the Kinase activity of ILK during tubular EMT induced by TGF-β1 and examined the therapeutic potential of an ILK inhibitor in obstructive nephropathy. TGF-β1 induced a biphasic activation of ILK in renal tubular epithelial cells, with rapid activation starting at 5 min and the second wave of activation peaking at 24 h; the latter paralleled the induction of ILK protein expression. Pharmacologic inhibition of ILK with small-molecule inhibitor QLT-0267 abolished TGF-β1–induced phosphorylation of Akt and glycogen synthase Kinase-3β, suppressed cyclin D1 expression, and largely restored the expression of E-cadherin and zonula occludens 1. Inhibition of ILK also blocked TGF-β1–mediated induction of fibronectin, Snail1, plasminogen activator inhibitor 1, and matrix metalloproteinase 2. In a mouse model of obstructive nephropathy, administration of QLT-0267 inhibited β-catenin accumulation; suppressed Snail1, α-smooth muscle actin, fibronectin, vimentin, and type I and type III collagen expression; and reduced total tissue collagen content. Inhibition of ILK did not affect kidney structure or function in normal mice. These findings suggest that increased ILK activity mediates EMT and the progression of renal fibrosis. Pharmacologic inhibition of ILK signaling may hold therapeutic potential for fibrotic kidney diseases.

  • essential role of Integrin Linked Kinase in podocyte biology bridging the Integrin and slit diaphragm signaling
    Journal of The American Society of Nephrology, 2006
    Co-Authors: Chunsun Dai, Shoukat Dedhar, Rene St-arnaud, Donna B Stolz, Sheldon I Bastacky, Youhua Liu
    Abstract:

    Integrin-Linked Kinase (ILK) has been implicated in the pathogenesis of proteinuria and congenital nephrotic syndrome. However, the function of ILK in glomerular podocyte in a physiologic setting remains unknown. In this study, a mouse model was generated in which ILK gene was selectively disrupted in podocytes by using the Cre-LoxP system. Podocyte-specific ablation of ILK resulted in heavy albuminuria, glomerulosclerosis, and kidney failure, which led to animal death beginning at 10 wk of age. Podocyte detachment and apoptosis were not observed at 4 wk of age, when albuminuria became prominent, indicating that they are not the initial cause of proteinuria. Electron microscopy revealed an early foot process effacement, as well as morphologic abnormality, in ILK-deficient podocytes. ILK deficiency caused an aberrant distribution of nephrin and α-actinin-4 in podocytes, whereas the localization of podocin and synaptopodin remained relatively intact. Co-immunoprecipitation demonstrated that ILK physically interacted with nephrin to form a ternary complex, and α-actinin-4 participated in ILK/nephrin complex formation. Therefore, ILK plays an essential role in specifying nephrin and α-actinin-4 distribution and in maintaining the slit diaphragm integrity and podocyte architecture. These results also illustrate that the Integrin and slit diaphragm signals in podocytes are intrinsically coupled through an ILK-dependent mechanism.

  • role for Integrin Linked Kinase in mediating tubular epithelial to mesenchymal transition and renal interstitial fibrogenesis
    Journal of Clinical Investigation, 2003
    Co-Authors: Junwei Yang, Chunsun Dai, Youhua Liu
    Abstract:

    Under pathologic conditions, renal tubular epithelial cells can undergo epithelial to mesenchymal transition (EMT), a phenotypic conversion that is believed to play a critical role in renal interstitial fibrogenesis. However, the underlying mechanism that governs this process remains largely unknown. Here we demonstrate that Integrin-Linked Kinase (ILK) plays an important role in mediating tubular EMT induced by TGF-β1. TGF-β1 induced ILK expression in renal tubular epithelial cells in a time- and dose-dependent manner, which was dependent on intracellular Smad signaling. Forced expression of ILK in human kidney proximal tubular epithelial cells suppressed E-cadherin expression and induced fibronectin expression and its extracellular assembly. ILK also induced MMP-2 expression and promoted cell migration and invasion in Matrigel. Conversely, ectopic expression of a dominant-negative, Kinase-dead form of ILK largely abrogated TGF-β1–initiated tubular cell phenotypic conversion. In vivo, ILK was markedly induced in renal tubular epithelia in mouse models of chronic renal diseases, and such induction was spatially and temporally correlated with tubular EMT. Moreover, inhibition of ILK expression by HGF was associated with blockade of tubular EMT and attenuation of renal fibrosis. These findings suggest that ILK is a critical mediator for tubular EMT and likely plays a crucial role in the pathogenesis of chronic renal fibrosis.