Slik Sterile-20 kinase regulates Moesin activity to promote epithelial integrity during tissue growth

Hipfner, David R.; Keller, N.; Cohen, Stephen M.

doi:10.1101/gad.303304

Cited by 92 publications

(139 citation statements)

References 38 publications

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“…Drosophila provides a particularly informative model because of its reduced number of kinases and a single ERM protein. In Drosophila, SLIK kinase is necessary for in-cell phosphorylation of moesin (5,6,18). Sequence analysis shows that insect SLIK is the ortholog of a 2-member subfamily of mammalian GCK kinase: LOK and SLK (KD sequence similarity 80% to SLK/LOK but Ͻ60% to other kinases).…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, the ERM phosphorylation site lacks R at either of these positions and has an unusual bulky aromatic residue at P-2. Second, studies in the important model organism Drosophila have implicated a kinase called SLIK, from a very divergent family of kinases, the STE20-related family (STE) (5,6,18). More recently one mammalian kinase in the STE family, HGK, was proposed to function as an ERM kinase (19).…”

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confidence: 99%

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LOK is a major ERM kinase in resting lymphocytes and regulates cytoskeletal rearrangement through ERM phosphorylation

Belkina

Liu

Hao

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

130

129

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ERM (ezrin-radixin-moesin) proteins mediate linkage of actin cytoskeleton to plasma membrane in many cells. ERM activity is regulated in part by phosphorylation at a C-terminal threonine, but the identity of ERM kinases is unknown in lymphocytes and incompletely defined in other mammalian cells. Our studies show that lymphocyte-oriented kinase (LOK) is an ERM kinase in vitro and in vivo. Mass spectrometric analysis indicates LOK is abundant at the lymphocyte plasma membrane and immunofluorescence studies show LOK enrichment at the plasma membrane near ERM. In vitro peptide specificity analyses characterize LOK as a basophilic kinase whose optimal substrate sequence resembles the ERM site, including unusual preference for tyrosine at P-2. LOK's activity on moesin peptide and protein was comparable to reported ERM kinases ROCK and PKC but unlike them LOK displayed preferential specificity for moesin compared to traditional basophilic kinase substrates. Two genetic approaches demonstrate a role for LOK in ERM phosphorylation: cell transfection with LOK kinase domain augments ERM phosphorylation and lymphocytes from LOK knockout mice have >50% reduction in ERM phosphorylation. The findings on localization and specificity argue that LOK is a direct ERM kinase. The knockout mice have normal hematopoietic cell development but notably lymphocyte migration and polarization in response to chemokine are enhanced. These functional alterations fit the current understanding of the role of ERM phosphorylation in regulating cortical reorganization. Thus, these studies identify a new ERM kinase of importance in lymphocytes and confirm the role of ERM phosphorylation in regulating cell shape and motility.ezrin ͉ kinase specificity ͉ knockout ͉ migration ͉ moesin T he ERM family in mammals consists of 3 closely related members: ezrin, radixin and moesin whose major function is to link cortical actin filaments to the plasma membrane (1-4). ERM N terminus (the FERM/band 4.1 domain) binds to plasma membrane both by direct interaction with phospholipids and by binding cytoplasmic tails of transmembrane proteins such as CD43, CD44, and ICAMs. ERM C terminus (''tail'') binds to filamentous actin. ERMs exist not only in this active conformation, but also in an inactive conformation where the C terminus binds to the FERM domain, thereby blocking binding sites on both FERM and tail. There is an evolutionarily conserved phosphorylation site near the C terminus whose phosphorylation contributes to stabilizing the active conformation. In mitotic cells ERM phosphorylation is critical for achieving spherical morphology and rigidity (5, 6). For lymphocytes circulating in blood, ERM phosphorylation is understood to contribute to rigidity and maintenance of microvilli. In response to chemotactic factors (especially chemokines) those lymphocytes transition into flexible migrating cells concurrent with rapid extensive dephosphorylation of ERM, which facilitates their polarization (7-10).Given the importance of ERM phosphorylation, it is essential to...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

LOK is a major ERM kinase in resting lymphocytes and regulates cytoskeletal rearrangement through ERM phosphorylation

Belkina

Liu

Hao

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

130

129

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“…Conversion to the active conformation occurs in a sequential mode by binding of the head domain to phosphatidylinositol 4,5-bisphosphate, unfolding and phosphorylation of a conserved threonine in the tail domain (Fievet et al, 2004;Ben-Aissa et al, 2012). In Drosophila, the latter step is mediated by the sterile 20 family kinase Slik (Hipfner et al, 2004). It has been proposed that activated Drosophila moesin influences the organization of the cortical cytoskeleton by acting antagonistically to the Rho signalling pathway (Speck et al, 2003;Xu et al, 2011).…”

Section: Morphogenesis Of the Secretory Cellsmentioning

confidence: 99%

Development of apical membrane organization and V-ATPase regulation in blowfly salivary glands

Baumann

Bauer

2013

Journal of Experimental Biology

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“…In considering NIK substrates that might regulate membrane protrusion, we tested ERM proteins because the Drosophila Ste20-like kinase Slik phosphorylates Drosophila moesin to maintain epithelial morphology (26). In vitro kinase assays showed that WT NIK tagged with a Myc epitope expressed in COS-7 cells and immunoprecipitated phosphorylated a GST fusion of the C terminus of moesin (M287-577) but not the N terminus (M1-310) or GST ( Fig.…”

Section: Nik Activity Is Necessary For Lamellipodium Extension By Egfmentioning

confidence: 99%

The Nck-interacting kinase phosphorylates ERM proteins for formation of lamellipodium by growth factors

Baumgärtner

Sillman²,

Blackwood³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

127

150

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The mammalian Ste20-like Nck-interacting kinase (NIK) and its orthologs Misshapen in Drosophila and Mig-15 in Caenorhabditis elegans have a conserved function in regulating cell morphology, although through poorly understood mechanisms. We report two previously unrecognized actions of NIK: regulation of lamellipodium formation by growth factors and phosphorylation of the ERM proteins ezrin, radixin, and moesin. ERM proteins regulate cell morphology and plasma membrane dynamics by reversibly anchoring actin filaments to integral plasma membrane proteins. In vitro assays show that NIK interacts directly with ERM proteins, binding their N termini and phosphorylating a conserved C-terminal threonine. In cells, NIK and phosphorylated ERM proteins localize at the distal margins of lamellipodia, and NIK activity is necessary for phosphorylation of ERM proteins induced by EGF and PDGF, but not by thrombin. Lamellipodium extension in response to growth factors is inhibited in cells expressing a kinase-inactive NIK, suppressed for NIK expression with siRNA oligonucleotides, or expressing ezrin T567A that cannot be phosphorylated. These data suggest that direct phosphorylation of ERM proteins by NIK constitutes a signaling mechanism controlling growth factor-induced membrane protrusion and cell morphology.ezrin ͉ moesin ͉ ste20 kinase ͉ membrane protrusion T he Nck-interacting kinase (NIK) is a member of the germinal center kinase subfamily of Ste20͞MAP4K serine͞threonine kinases (1). Closely related to NIK are the mammalian kinases TNIK (2), MINK (3), and NRK͞NESK (4) and orthologs Misshapen (Msn) in Drosophila (5) and MIG-15 in Caenorhabditis elegans (6). NIK and its orthologs share a common function in regulating cell shape and migration. In mice, homozygous knockout of NIK results in early embryonic lethality with defects in mesoderm migration (7), and expression of kinase-inactive NIK attenuates epithelial cell invasion (8). Msn functions in determining epithelial polarity, dorsal closure. and neuronal targeting (5, 9, 10), and MIG-15 controls axonal navigation (6). NIK (1) and Msn (5) also share a conserved activation of the JNK pathway. NIK, however, does not directly phosphorylate JNK, nor do NIK nullizygous embryos precisely phenocopy mice lacking JNK1 or JNK2 (7). Additionally, activation of JNK is not associated with dynamic changes in cell morphology. Hence, NIK substrates that control cell morphogenesis have not been identified.We now report that the ERM proteins ezrin, radixin, and moesin are substrates for NIK. ERM proteins regulate cell morphology by cross-linking actin filaments to the plasma membrane. The N-terminal FERM (4.1 ERM) domain of ERM proteins binds to integral plasma membrane proteins and the C terminus binds F-actin (11). ERM proteins control cell shape primarily by regulating membrane protrusions and cell-substrate adhesion. In epithelial cells ERM proteins are necessary for the formation of apical microvilli (12)(13)(14). In fibroblasts ERM proteins regulate the assembly of focal adhesions (...

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Slik Sterile-20 kinase regulates Moesin activity to promote epithelial integrity during tissue growth

Cited by 92 publications

References 38 publications

LOK is a major ERM kinase in resting lymphocytes and regulates cytoskeletal rearrangement through ERM phosphorylation

LOK is a major ERM kinase in resting lymphocytes and regulates cytoskeletal rearrangement through ERM phosphorylation

Development of apical membrane organization and V-ATPase regulation in blowfly salivary glands

The Nck-interacting kinase phosphorylates ERM proteins for formation of lamellipodium by growth factors

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