Publications (13) View all
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Article: Localization and potential function of kindlin-1 in periodontal tissues.
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ABSTRACT: Kindlin-1 is an intracellular focal adhesion protein that regulates the actin cytoskeleton. Patients suffering from Kindler syndrome have a homologous mutation of the kindlin-1 gene and develop skin blisters, periodontal disease, and intestinal complications because of deficient adhesion of the basal epithelial cells. We investigated kindlin-1 localization in periodontal tissue and its functions in cultured keratinocytes and showed that kindlin-1 co-localizes with migfilin and paxillin in the basal epithelial cells of oral mucosa and in cultured keratinocytes. The kindlin-1-deficient oral mucosal tissue from a patient with Kindler syndrome showed a complete lack of paxillin and reduced migfilin immunostaining in the basal keratinocytes. Co-immunoprecipitation showed that migfilin directly interacted with kindlin-1. RNA interference-induced kindlin-1 deficiency in keratinocytes led to an altered distribution of migfilin-containing focal adhesions, reduced cell spreading, decreased cell proliferation, and decelerated cell migration. Disruption of microtubules in the kindlin-1-deficient cells further reduced cell spreading, suggesting that microtubules can partially compensate for kindlin-1 deficiency. Kindlin-1 supported mature cell-extracellular matrix adhesions of keratinocytes, as downregulation of kindlin-1 expression significantly reduced the cell-adhesion strength. In summary, kindlin-1 interacts with migfilin and plays a crucial role in actin-dependent keratinocyte cell adhesion essential for epidermal and periodontal health.European Journal Of Oral Sciences 10/2009; 117(5):518-27. · 1.88 Impact Factor -
Article: Localization and potential function of kindlin‐1 in periodontal tissues
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ABSTRACT: Kindlin-1 is an intracellular focal adhesion protein that regulates the actin cytoskeleton. Patients suffering from Kindler syndrome have a homologous mutation of the kindlin-1 gene and develop skin blisters, periodontal disease, and intestinal complications because of deficient adhesion of the basal epithelial cells. We investigated kindlin-1 localization in periodontal tissue and its functions in cultured keratinocytes and showed that kindlin-1 co-localizes with migfilin and paxillin in the basal epithelial cells of oral mucosa and in cultured keratinocytes. The kindlin-1-deficient oral mucosal tissue from a patient with Kindler syndrome showed a complete lack of paxillin and reduced migfilin immunostaining in the basal keratinocytes. Co-immunoprecipitation showed that migfilin directly interacted with kindlin-1. RNA interference-induced kindlin-1 deficiency in keratinocytes led to an altered distribution of migfilin-containing focal adhesions, reduced cell spreading, decreased cell proliferation, and decelerated cell migration. Disruption of microtubules in the kindlin-1-deficient cells further reduced cell spreading, suggesting that microtubules can partially compensate for kindlin-1 deficiency. Kindlin-1 supported mature cell–extracellular matrix adhesions of keratinocytes, as downregulation of kindlin-1 expression significantly reduced the cell-adhesion strength. In summary, kindlin-1 interacts with migfilin and plays a crucial role in actin-dependent keratinocyte cell adhesion essential for epidermal and periodontal health.European Journal Of Oral Sciences 09/2009; 117(5):518 - 527. · 1.88 Impact Factor -
Article: Reversion-induced LIM interaction with Src reveals a novel Src inactivation cycle.
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ABSTRACT: Aberrant Src activation plays prominent roles in cancer progression. However, how Src is activated in cancer cells is largely unknown. Genetic Src-activating mutations are rare and, therefore, are insufficient to account for Src activation commonly found in human cancers. In this study, we show that reversion-induced LIM (RIL), which is frequently lost in colon and other cancers as a result of epigenetic silencing, suppresses Src activation. Mechanistically, RIL suppresses Src activation through interacting with Src and PTPL1, allowing PTPL1-dependent dephosphorylation of Src at the activation loop. Importantly, the binding of RIL to Src is drastically reduced upon Src inactivation. Our results reveal a novel Src inactivation cycle in which RIL preferentially recognizes active Src and facilitates PTPL1-mediated inactivation of Src. Inactivation of Src, in turn, promotes dissociation of RIL from Src, allowing the initiation of a new Src inactivation cycle. Epigenetic silencing of RIL breaks this Src inactivation cycle and thereby contributes to aberrant Src activation in human cancers.The Journal of Cell Biology 04/2009; 184(6):785-92. · 10.26 Impact Factor -
Article: Structural basis of focal adhesion localization of LIM-only adaptor PINCH by integrin-linked kinase.
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ABSTRACT: The LIM-only adaptor PINCH (the particularly interesting cysteine- and histidine-rich protein) plays a pivotal role in the assembly of focal adhesions (FAs), supramolecular complexes that transmit mechanical and biochemical information between extracellular matrix and actin cytoskeleton, regulating diverse cell adhesive processes such as cell migration, cell spreading, and survival. A key step for the PINCH function is its localization to FAs, which depends critically on the tight binding of PINCH to integrin-linked kinase (ILK). Here we report the solution NMR structure of the core ILK.PINCH complex (28 kDa, K(D) approximately 68 nm) involving the N-terminal ankyrin repeat domain (ARD) of ILK and the first LIM domain (LIM1) of PINCH. We show that the ILK ARD exhibits five sequentially stacked ankyrin repeat units, which provide a large concave surface to grip the two contiguous zinc fingers of the PINCH LIM1. The highly electrostatic interface is evolutionally conserved but differs drastically from those of known ARD and LIM bound to other types of protein domains. Consistently mutation of a hot spot in LIM1, which is not conserved in other LIM domains, disrupted the PINCH binding to ILK and abolished the PINCH targeting to FAs. These data provide atomic insight into a novel modular recognition and demonstrate how PINCH is specifically recruited by ILK to mediate the FA assembly and cell-extracellular matrix communication.Journal of Biological Chemistry 01/2009; 284(9):5836-44. · 4.77 Impact Factor -
Article: PINCH-1 regulates the ERK-Bim pathway and contributes to apoptosis resistance in cancer cells.
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ABSTRACT: Resistance to apoptosis is a hallmark of cancer cells. We report here that PINCH-1, a cytoplasmic component of cell-extracellular matrix adhesions, is required for protection of multiple types of cancer cells from apoptosis. Furthermore, using HT-1080 fibrosarcoma cells as a model system, we have investigated the signaling pathway through which PINCH-1 contributes to apoptosis resistance. Loss of PINCH-1 markedly increases the level of Bim and promotes Bim translocation to mitochondria, resulting in activation of the intrinsic apoptosis pathway. Depletion of Bim completely blocked apoptosis induced by the loss of PINCH-1. Thus, PINCH-1 contributes to apoptosis resistance through suppression of Bim. Mechanistically, PINCH-1 suppresses Bim not only transcriptionally but also post-transcriptionally. PINCH-1 promotes activating phosphorylation of Src family kinase and ERK1/2. Consistent with this, ERK1/2-mediated Ser(69) phosphorylation of Bim, a key signal for turnover of Bim, is suppressed by the removal of PINCH-1. Our results demonstrate a strong dependence of multiple types of apoptosis-resistant cancer cells on PINCH-1 and provide new insights into the molecular mechanism by which cancer cells are protected from apoptosis.Journal of Biological Chemistry 03/2008; 283(5):2508-17. · 4.77 Impact Factor
