Suppression of Tubulin Polymerization by the LKB1-Microtubule-associated Protein/Microtubule Affinity-regulating Kinase Signaling

Kojima, Yasushi; Miyoshi, Hiroyuki; Clevers, Hans; Oshima, Masanobu; Aoki, Masahiro; Taketo, Makoto Mark

doi:10.1074/jbc.m700590200

Cited by 54 publications

(53 citation statements)

References 50 publications

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“…(Fig. 2A) (17). The cells infected with Adv-LKB1 alone showed similar activity of PAK1 to those infected with Adv-Cre alone (control cells) (Fig.…”

Section: Knockdown Of Endogenous Lkb1 Enhances Cell Migrationmentioning

confidence: 76%

“…For example, PAK1 stabilizes microtubules through stathmin/Op18 phosphorylation (43,44). Therefore, LKB1 also may contribute to microtubule destabilization by regulating PAK1, whereas we have reported previously that LKB1 inhibits tubulin polymerization through activation of MARK2 (17). Further investigation is needed to address the role of LKB1 in various downstream processes of PAK1 other than cell motility.…”

Section: Discussionmentioning

confidence: 97%

“…In addition to growth control, LKB1 also plays important roles in establishing cell polarity in mammalian cells (14). LKB1 regulates tight junction assembly and cell polarity through AMPK in mammalian cells (15,16), and we have shown that LKB1 suppresses tubulin polymerization by activating MARK microtubule-associated protein signaling (17). We have also reported that HCCs in Lkb1(ϩ/Ϫ) mice metastasize to the lungs (10).…”

mentioning

confidence: 86%

“…200 ml of 2ϫYT medium (1.6% tryptone, 1% yeast extract, and 0.5% NaCl) medium was inoculated with E. coli (BL21 strain) containing the recombinant pGEX-2TK plasmid that encodes GST-VASP-(158 -277), or the recombinant pGEX-6P-1 plasmid that encodes GST-PAK1-PBD, GST-PAK1-PBD-T109A, GST-PAK1-K299R, or GST-PAK1-T109A/K299R and was incubated at 37°C in the presence of 100 g/ml ampicillin until A 600 reached 0.8. To induce expression of the GST-tagged proteins, isopropyl-D-thiogalactopyranoside was added at 100 M. After culture for 24 additional hours at 25°C, cells were harvested, and recombinant proteins were purified as described previously (17).…”

Section: Methodsmentioning

confidence: 99%

“…NM_001003787. HA and FLAG tags were attached to the N termini of LKB1 and STRAD, as described previously (17). LKB1 (kinase-dead, a catalytically inactive version of LKB1 with a D194A mutation (30)), was generated with QuikChange II site-directed mutagenesis kit (Stratagene, La Jolla, CA) according to the manufacturer's protocol.…”

Section: Methodsmentioning

confidence: 99%

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LKB1 Suppresses p21-activated Kinase-1 (PAK1) by Phosphorylation of Thr109 in the p21-binding Domain

Deguchi

Miyoshi

Kojima

et al. 2010

Journal of Biological Chemistry

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The serine/threonine protein kinase LKB1 is a tumor suppressor gene mutated in Peutz-Jeghers syndrome patients. The mutations are found also in several types of sporadic cancer. Although LKB1 is implicated in suppression of cell growth and metastasis, the detailed mechanisms have not yet been elucidated. In this study, we investigated the effect of LKB1 on cell motility, whose acquisition occurs in early metastasis. The knockdown of LKB1 enhanced cell migration and PAK1 activity in human colon cancer HCT116 cells, whereas forced expression of LKB1 in Lkb1-null mouse embryonic fibroblasts suppressed PAK1 activity and PAK1-mediated cell migration simultaneously. Notably, LKB1 directly phosphorylated PAK1 at Thr 109 in the p21-binding domain in vitro. The phosphomimetic T109E mutant showed significantly lower protein kinase activity than wild-type PAK1, suggesting that the phosphorylation at Thr 109 by LKB1 was responsible for suppression of PAK1. Consistently, the nonphosphorylatable T109A mutant was resistant to suppression by LKB1. Furthermore, we found that PAK1 was activated in the hepatocellular carcinomas and the precancerous liver lesions of Lkb1(؉/؊) mice. Taken together, these results suggest that PAK1 is a direct downstream target of LKB1 and plays an essential role in LKB1-induced suppression of cell migration.LKB1 is a serine/threonine kinase whose mutations have been found not only in Peutz-Jeghers syndrome patients (1-3) but also in various types of sporadic cancer (4 -6). These results suggest that LKB1 is a tumor suppressor gene. In addition, we and others (7-9) have previously shown that the heterozygous Lkb1 mutations in mice cause gastrointestinal hamartomas after 20 weeks of age and cause hepatocellular carcinomas (HCCs) 2 after 50 weeks (10). Notably, the Lkb1 gene in all HCC and hepatic precancerous lesions shows loss of heterozygosity (10, 11). These phenotypes in Lkb1(ϩ/Ϫ) mice further indicate that LKB1 is a tumor suppressor gene. In mammalian cells, LKB1 forms a complex with STE20-related adaptor pseudokinase (STRAD) and scaffolding protein MO25, both of which are required for LKB1 enzymatic activity (12, 13). It can phosphorylate and activate at least 14 kinases, including AMP-activated protein kinase (AMPK) and microtubule-associated protein/microtubule affinity-regulating kinases (MARKs) (5). Activation of AMPK by LKB1 leads to inactivation of mammalian target of rapamycin complex 1 via phosphorylation of the tuberous sclerosis complex 1/2, and this pathway has been implicated in tumor suppressor functions of LKB1. In addition to growth control, LKB1 also plays important roles in establishing cell polarity in mammalian cells (14). LKB1 regulates tight junction assembly and cell polarity through AMPK in mammalian cells (15, 16), and we have shown that LKB1 suppresses tubulin polymerization by activating MARK microtubule-associated protein signaling (17). We have also reported that HCCs in Lkb1(ϩ/Ϫ) mice metastasize to the lungs (10). However, the mechanisms by which LKB1 suppresses canc...

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“…(Fig. 2A) (17). The cells infected with Adv-LKB1 alone showed similar activity of PAK1 to those infected with Adv-Cre alone (control cells) (Fig.…”

Section: Knockdown Of Endogenous Lkb1 Enhances Cell Migrationmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 97%

mentioning

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

LKB1 Suppresses p21-activated Kinase-1 (PAK1) by Phosphorylation of Thr109 in the p21-binding Domain

Deguchi

Miyoshi

Kojima

et al. 2010

Journal of Biological Chemistry

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Role of LKB1‐SAD/MARK pathway in neuronal polarization

Shelly

Poo

2011

Developmental Neurobiology

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The formation of axon/dendrite polarity is critical for the neuron to perform its signaling function in the brain. Recent advance in our understanding of cellular and molecular mechanisms underlying the development and maintenance of neuronal polarity has been greatly facilitated by the use of the culture system of dissociated hippocampal neurons. Among many polarization-related proteins, we here focus on the mammalian LKB1, the counterpart of the C. elegans Par-4, which is an upstream regulator among six Par (partitioning-defective) genes that act as master regulators of cell polarity in different cell types across evolutionary distant species. Recent studies have identified LKB1 and its downstream targets SAD/MARK kinases (mammalian homologs of Par-1) as key regulators of neuronal polarization and axon development in cultured neurons and in developing cortical neurons in vivo. We will review the properties of and interactions among proteins in this LKB1-SAD/MARK pathway, drawing upon information obtained from both neuronal and non-neuronal systems. Due to central role of the protein kinase A-dependent phosphorylation of LKB1 in the activation of this pathway, we will review recent findings on how cAMP and cGMP signaling may serve as antagonistic second messengers for axon/dendrite development, and how these cyclic nucleotides may mediate the action of extracellular polarizing factors by modulating the activity of the LKB1-SAD/MARK pathway.

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