1
|
Shah K, Cook M. LIMK2: A Multifaceted kinase with pleiotropic roles in human physiology and pathologies. Cancer Lett 2023; 565:216207. [PMID: 37141984 PMCID: PMC10316521 DOI: 10.1016/j.canlet.2023.216207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/06/2023]
Abstract
LIMK2, a serine-specific kinase, was discovered as an actin dynamics regulating kinase. Emerging studies have shown its pivotal role in numerous human malignancies and neurodevelopmental disorder. Inducible knockdown of LIMK2 fully reverses tumorigenesis, underscoring its potential as a clinical target. However, the molecular mechanisms leading to its upregulation and its deregulated activity in various diseases largely remain unknown. Similarly, LIMK2's peptide substrate specificity has not been analyzed. This is particularly important for LIMK2, a kinase almost three decades old, as only a handful of its substrates are known to date. As a result, most of LIMK2's physiological and pathological roles have been assigned to its regulation of actin dynamics via cofilin. This review focuses on LIMK2's unique catalytic mechanism, substrate specificity and its upstream regulators at transcriptional, post-transcriptional and post-translational stages. Moreover, emerging studies have unveiled a few tumor suppressors and oncogenes as LIMK2's direct substrates, which in turn have uncovered novel molecular mechanisms by which it plays pleiotropic roles in human physiology and pathologies independent of actin dynamics.
Collapse
Affiliation(s)
- Kavita Shah
- Department of Chemistry and Purdue University Center for Cancer Research, 560 Oval Drive, West Lafayette, IN, 47907, USA.
| | - Mason Cook
- Department of Chemistry and Purdue University Center for Cancer Research, 560 Oval Drive, West Lafayette, IN, 47907, USA
| |
Collapse
|
2
|
Ribba AS, Fraboulet S, Sadoul K, Lafanechère L. The Role of LIM Kinases during Development: A Lens to Get a Glimpse of Their Implication in Pathologies. Cells 2022; 11:cells11030403. [PMID: 35159213 PMCID: PMC8834001 DOI: 10.3390/cells11030403] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/18/2022] [Accepted: 01/22/2022] [Indexed: 12/24/2022] Open
Abstract
The organization of cell populations within animal tissues is essential for the morphogenesis of organs during development. Cells recognize three-dimensional positions with respect to the whole organism and regulate their cell shape, motility, migration, polarization, growth, differentiation, gene expression and cell death according to extracellular signals. Remodeling of the actin filaments is essential to achieve these cell morphological changes. Cofilin is an important binding protein for these filaments; it increases their elasticity in terms of flexion and torsion and also severs them. The activity of cofilin is spatiotemporally inhibited via phosphorylation by the LIM domain kinases 1 and 2 (LIMK1 and LIMK2). Phylogenetic analysis indicates that the phospho-regulation of cofilin has evolved as a mechanism controlling the reorganization of the actin cytoskeleton during complex multicellular processes, such as those that occur during embryogenesis. In this context, the main objective of this review is to provide an update of the respective role of each of the LIM kinases during embryonic development.
Collapse
|
3
|
LIM-Kinases in Synaptic Plasticity, Memory, and Brain Diseases. Cells 2021; 10:cells10082079. [PMID: 34440848 PMCID: PMC8391678 DOI: 10.3390/cells10082079] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/30/2021] [Accepted: 08/04/2021] [Indexed: 12/12/2022] Open
Abstract
Learning and memory require structural and functional modifications of synaptic connections, and synaptic deficits are believed to underlie many brain disorders. The LIM-domain-containing protein kinases (LIMK1 and LIMK2) are key regulators of the actin cytoskeleton by affecting the actin-binding protein, cofilin. In addition, LIMK1 is implicated in the regulation of gene expression by interacting with the cAMP-response element-binding protein. Accumulating evidence indicates that LIMKs are critically involved in brain function and dysfunction. In this paper, we will review studies on the roles and underlying mechanisms of LIMKs in the regulation of long-term potentiation (LTP) and depression (LTD), the most extensively studied forms of long-lasting synaptic plasticity widely regarded as cellular mechanisms underlying learning and memory. We will also discuss the involvement of LIMKs in the regulation of the dendritic spine, the structural basis of synaptic plasticity, and memory formation. Finally, we will discuss recent progress on investigations of LIMKs in neurological and mental disorders, including Alzheimer’s, Parkinson’s, Williams–Beuren syndrome, schizophrenia, and autism spectrum disorders.
Collapse
|
4
|
Mao R, Deng R, Wei Y, Han L, Meng Y, Xie W, Jia Z. LIMK1 and LIMK2 regulate cortical development through affecting neural progenitor cell proliferation and migration. Mol Brain 2019; 12:67. [PMID: 31319858 PMCID: PMC6637558 DOI: 10.1186/s13041-019-0487-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 07/02/2019] [Indexed: 02/06/2023] Open
Abstract
LIMK1 and LIMK2 are key downstream targets to mediate the effects of the Rho family small GTPases and p21-activated kinases (PAK) in the regulation of the actin cytoskeleton. LIMKs are also critical for synaptic transmission, plasticity and memory formation. Changes in LIMK signaling are associated with several neurodevelopmental and neurodegenerative diseases, including autism, intellectual disability and Alzheimer's disease. However, the role of LIMK signaling in brain development remains unknown. In this study, we used LIMK1 KO and LIMK2 KO mice to investigate the role of LIMK signaling in the cerebral cortical development. We found that these KO mice are reduced in the number of pyramidal neurons in upper cortical layers and this reduction is accompanied by a smaller pool of neural progenitor cells and impaired neuronal migration. These results are similar to those found in PAK1 KO mice and suggest that LIMK-dependent actin regulation may play a key role in mediating the effects of PAK1 and Rho signaling in the regulation of cortical development.
Collapse
Affiliation(s)
- Rui Mao
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, 2 Sipailou Road, Nanjing, 210096, China
| | - Rui Deng
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, 2 Sipailou Road, Nanjing, 210096, China
| | - Yan Wei
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, 2 Sipailou Road, Nanjing, 210096, China
| | - Lifang Han
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, 2 Sipailou Road, Nanjing, 210096, China
| | - Yanghong Meng
- Neurosciences & Mental Health, The Hospital for Sick Children, 555 University Ave, Toronto, ON, M5G 1X8, Canada
| | - Wei Xie
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, 2 Sipailou Road, Nanjing, 210096, China.
| | - Zhengping Jia
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, 2 Sipailou Road, Nanjing, 210096, China. .,Neurosciences & Mental Health, The Hospital for Sick Children, 555 University Ave, Toronto, ON, M5G 1X8, Canada. .,Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
| |
Collapse
|
5
|
Kovaleva TF, Maksimova NS, Zhukov IY, Pershin VI, Mukhina IV, Gainullin MR. Cofilin: Molecular and Cellular Functions and Its Role in the Functioning of the Nervous System. NEUROCHEM J+ 2019. [DOI: 10.1134/s1819712419010124] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
6
|
Rho GTPases in Intellectual Disability: From Genetics to Therapeutic Opportunities. Int J Mol Sci 2018; 19:ijms19061821. [PMID: 29925821 PMCID: PMC6032284 DOI: 10.3390/ijms19061821] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 06/14/2018] [Accepted: 06/16/2018] [Indexed: 12/22/2022] Open
Abstract
Rho-class small GTPases are implicated in basic cellular processes at nearly all brain developmental steps, from neurogenesis and migration to axon guidance and synaptic plasticity. GTPases are key signal transducing enzymes that link extracellular cues to the neuronal responses required for the construction of neuronal networks, as well as for synaptic function and plasticity. Rho GTPases are highly regulated by a complex set of activating (GEFs) and inactivating (GAPs) partners, via protein:protein interactions (PPI). Misregulated RhoA, Rac1/Rac3 and cdc42 activity has been linked with intellectual disability (ID) and other neurodevelopmental conditions that comprise ID. All genetic evidences indicate that in these disorders the RhoA pathway is hyperactive while the Rac1 and cdc42 pathways are consistently hypoactive. Adopting cultured neurons for in vitro testing and specific animal models of ID for in vivo examination, the endophenotypes associated with these conditions are emerging and include altered neuronal networking, unbalanced excitation/inhibition and altered synaptic activity and plasticity. As we approach a clearer definition of these phenotype(s) and the role of hyper- and hypo-active GTPases in the construction of neuronal networks, there is an increasing possibility that selective inhibitors and activators might be designed via PPI, or identified by screening, that counteract the misregulation of small GTPases and result in alleviation of the cognitive condition. Here we review all knowledge in support of this possibility.
Collapse
|
7
|
Cuberos H, Vallée B, Vourc'h P, Tastet J, Andres CR, Bénédetti H. Roles of LIM kinases in central nervous system function and dysfunction. FEBS Lett 2015; 589:3795-806. [PMID: 26545494 DOI: 10.1016/j.febslet.2015.10.032] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 10/21/2015] [Accepted: 10/28/2015] [Indexed: 12/30/2022]
Abstract
LIM kinase 1 (LIMK1) and LIM kinase 2 (LIMK2) regulate actin dynamics by phosphorylating cofilin. In this review, we outline studies that have shown an involvement of LIMKs in neuronal function and we detail some of the pathways and molecular mechanisms involving LIMKs in neurodevelopment and synaptic plasticity. We also review the involvement of LIMKs in neuronal diseases and emphasize the differences in the regulation of LIMKs expression and mode of action. We finally present the existence of a cofilin-independent pathway also involved in neuronal function. A better understanding of the differences between both LIMKs and of the precise molecular mechanisms involved in their mode of action and regulation is now required to improve our understanding of the physiopathology of the neuronal diseases associated with LIMKs.
Collapse
Affiliation(s)
- H Cuberos
- CNRS UPR 4301, CBM, Orléans, France; UMR INSERM U930, Université François-Rabelais, Tours, France
| | - B Vallée
- CNRS UPR 4301, CBM, Orléans, France
| | - P Vourc'h
- UMR INSERM U930, Université François-Rabelais, Tours, France; CHRU de Tours, Service de Biochimie et de Biologie Moléculaire, Tours, France
| | - J Tastet
- University Medical Center Utrecht, Brain Center Rudolf Magnus, Utrecht, Netherlands
| | - C R Andres
- UMR INSERM U930, Université François-Rabelais, Tours, France; CHRU de Tours, Service de Biochimie et de Biologie Moléculaire, Tours, France
| | | |
Collapse
|
8
|
Ohashi K. Roles of cofilin in development and its mechanisms of regulation. Dev Growth Differ 2015; 57:275-90. [DOI: 10.1111/dgd.12213] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Revised: 03/18/2015] [Accepted: 03/19/2015] [Indexed: 02/06/2023]
Affiliation(s)
- Kazumasa Ohashi
- Department of Biomolecular Sciences; Graduate School of Life Sciences; Tohoku University; Sendai Miyagi 980-8578 Japan
| |
Collapse
|
9
|
Rumyantsev AM, Zakharov GA, Zhuravlev AV, Padkina MV, Savvateeva-Popova EV, Sambuk EV. Expression of the Drosophila melanogaster limk1 gene 3′-UTRs mRNA in yeast Saccharomyces cerevisiae. RUSS J GENET+ 2014. [DOI: 10.1134/s102279541406009x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
|
10
|
Koch JC, Tönges L, Barski E, Michel U, Bähr M, Lingor P. ROCK2 is a major regulator of axonal degeneration, neuronal death and axonal regeneration in the CNS. Cell Death Dis 2014; 5:e1225. [PMID: 24832597 PMCID: PMC4047920 DOI: 10.1038/cddis.2014.191] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 03/26/2014] [Accepted: 03/28/2014] [Indexed: 12/19/2022]
Abstract
The Rho/ROCK/LIMK pathway is central for the mediation of repulsive environmental signals in the central nervous system. Several studies using pharmacological Rho-associated protein kinase (ROCK) inhibitors have shown positive effects on neurite regeneration and suggest additional pro-survival effects in neurons. However, as none of these drugs is completely target specific, it remains unclear how these effects are mediated and whether ROCK is really the most relevant target of the pathway. To answer these questions, we generated adeno-associated viral vectors to specifically downregulate ROCK2 and LIM domain kinase (LIMK)-1 in rat retinal ganglion cells (RGCs) in vitro and in vivo. We show here that specific knockdown of ROCK2 and LIMK1 equally enhanced neurite outgrowth of RGCs on inhibitory substrates and both induced substantial neuronal regeneration over distances of more than 5 mm after rat optic nerve crush (ONC) in vivo. However, only knockdown of ROCK2 but not LIMK1 increased survival of RGCs after optic nerve axotomy. Moreover, knockdown of ROCK2 attenuated axonal degeneration of the proximal axon after ONC assessed by in vivo live imaging. Mechanistically, we demonstrate here that knockdown of ROCK2 resulted in decreased intraneuronal activity of calpain and caspase 3, whereas levels of pAkt and collapsin response mediator protein 2 and autophagic flux were increased. Taken together, our data characterize ROCK2 as a specific therapeutic target in neurodegenerative diseases and demonstrate new downstream effects of ROCK2 including axonal degeneration, apoptosis and autophagy.
Collapse
Affiliation(s)
- J C Koch
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - L Tönges
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - E Barski
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - U Michel
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - M Bähr
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - P Lingor
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| |
Collapse
|
11
|
Mizuno T, Omata N, Murata T, Mitsuya H, Maruoka N, Mita K, Kiyono Y, Okazawa H, Ikeda H, Wada Y. Mania: Not the opposite of depression, but an extension? Neuronal plasticity and polarity. Med Hypotheses 2013; 81:175-9. [DOI: 10.1016/j.mehy.2013.05.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 05/05/2013] [Accepted: 05/15/2013] [Indexed: 10/26/2022]
|
12
|
Deng GF, Liu SJ, Sun XS, Sun WW, Zhao QH, Liao WP, Yi YH, Long YS. A conserved region in the 3' untranslated region of the human LIMK1 gene is critical for proper expression of LIMK1 at the post-transcriptional level. Neurosci Bull 2013; 29:348-54. [PMID: 23700283 DOI: 10.1007/s12264-013-1341-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 10/02/2012] [Indexed: 11/30/2022] Open
Abstract
LIM kinase 1 (LIMK1), a cytosolic serine/threonine kinase, regulates actin filament dynamics and reorganization and is involved in neuronal development and brain function. Abnormal expression of LIMK1 is associated with several neurological disorders. In this study, we performed a conservation analysis using Vector NTI (8.0) software. The dualluciferase reporter assay and real-time quantitative RT-PCR were used to assess the protein and mRNA levels of the reporter gene, respectively. We found that a region ranging from nt +884 to +966 in the human LIMK1 3' untranslated region (UTR) was highly conserved in the mouse Limk1 3' UTR and formed a structure containing several loops and stems. Luciferase assay showed that the relative luciferase activity of the mutated construct with the conserved region deleted, pGL4-hLIMK1-3U-M, in SH-SY5Y and HEK-293 cells was only ~60% of that of the wild-type construct pGL4-hLIMK1-3U, indicating that the conserved region is critical for the reporter gene expression. Real-time quantitative RT-PCR analysis demonstrated that the relative Luc2 mRNA levels in SH-SY5Y and HEK293 cells transfected with pGL4-hLIMK1-3U-M decreased to ~50% of that in cells transfected with pGL4-hLIMK1-3U, suggesting an important role of the conserved region in maintaining Luc2 mRNA stability. Our study suggests that the conserved region in the LIMK1 3' UTR is involved in regulating LIMK1 expression at the post-transcriptional level, which may help reveal the mechanism underlying the regulation of LIMK1 expression in the central nervous system and explore the relationship between the 3'-UTR mutant and neurological disorders.
Collapse
Affiliation(s)
- Guang-Fei Deng
- Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Institute of Neuroscience, Guangzhou, 510260, China
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Saito A, Miyajima K, Akatsuka J, Kondo H, Mashiko T, Kiuchi T, Ohashi K, Mizuno K. CaMKIIβ-mediated LIM-kinase activation plays a crucial role in BDNF-induced neuritogenesis. Genes Cells 2013; 18:533-43. [PMID: 23600483 DOI: 10.1111/gtc.12054] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 03/10/2013] [Indexed: 12/01/2022]
Abstract
LIM-kinase 1 (LIMK1) regulates actin cytoskeletal reorganization by phosphorylating and inactivating actin-depolymerizing factor and cofilin. We examined the role of LIMK1 in brain-derived neurotrophic factor (BDNF)-induced neuritogenesis in primary-cultured rat cortical neurons. Knockdown of LIMK1 or expression of a kinase-dead LIMK1 mutant suppressed BDNF-induced enhancement of primary neurite formation. By contrast, expression of an active form of LIMK1 promoted primary neuritogenesis in the absence of BDNF. BDNF-induced neuritogenesis was inhibited by KN-93, an inhibitor of Ca(2+) /calmodulin-dependent protein kinases (CaMKs), but not by STO-609, an inhibitor of CaMK-kinase (CaMKK). CaMKK activity is required for the activation of CaMKI and CaMKIV, but not CaMKII, which suggests that CaMKII is principally involved in BDNF-induced enhancement of neuritogenesis. Knockdown of CaMKIIβ, but not CaMKIIα, suppressed BDNF-induced neuritogenesis. Active CaMKIIβ promoted neuritogenesis, and this promotion was inhibited by knockdown of LIMK1, indicating that CaMKIIβ is involved in BDNF-induced neuritogenesis via activation of LIMK1. Furthermore, in vitro kinase assays revealed that CaMKIIβ phosphorylates LIMK1 at Thr-508 in the kinase domain and activates the cofilin-phosphorylating activity of LIMK1. In summary, these results suggest that CaMKIIβ-mediated activation of LIMK1 plays a crucial role in BDNF-induced enhancement of primary neurite formation.
Collapse
Affiliation(s)
- Akihiko Saito
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Signaling mechanisms and functional roles of cofilin phosphorylation and dephosphorylation. Cell Signal 2012; 25:457-69. [PMID: 23153585 DOI: 10.1016/j.cellsig.2012.11.001] [Citation(s) in RCA: 284] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 11/05/2012] [Indexed: 01/12/2023]
Abstract
Cofilin and actin-depolymerizing factor (ADF) are actin-binding proteins that play an essential role in regulating actin filament dynamics and reorganization by stimulating the severance and depolymerization of actin filaments. Cofilin/ADF are inactivated by phosphorylation at the serine residue at position 3 by LIM-kinases (LIMKs) and testicular protein kinases (TESKs) and are reactivated by dephosphorylation by the slingshot (SSH) family of protein phosphatases and chronophin. This review describes recent advances in our understanding of the signaling mechanisms regulating LIMKs and SSHs and the functional roles of cofilin phospho-regulation in cell migration, tumor invasion, mitosis, neuronal development, and synaptic plasticity. Accumulating evidence demonstrates that the phospho-regulation of cofilin/ADF is a key convergence point of cell signaling networks that link extracellular stimuli to actin cytoskeletal dynamics and that spatiotemporal control of cofilin/ADF activity by LIMKs and SSHs plays a crucial role in a diverse array of cellular and physiological processes. Perturbations in the normal control of cofilin/ADF activity underlie many pathological conditions, including cancer metastasis and neurological and cardiovascular disorders.
Collapse
|
15
|
LIMK2d, a truncated isoform of Lim kinase 2 regulates neurite growth in absence of the LIM kinase domain. Biochem Biophys Res Commun 2012; 420:247-52. [PMID: 22405825 DOI: 10.1016/j.bbrc.2012.02.134] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 02/24/2012] [Indexed: 01/16/2023]
Abstract
Lim kinase 2 isoforms, LIMK2a and LIMK2b, phosphorylate cofilin leading to remodeling of actin cytoskeleton during neuronal differentiation. The expression and function of the LIMK2d isoform, missing the kinase domain, remain unknown. We analyzed the expression of LIMK2 splice variants in adult rat brain and in cultures of rat neural stem cells by RT-QPCR. All three splice variants were expressed in adult cortex, hippocampus and cerebellum. Limk2a and Limk2d expression, but not Limk2b, increased during neuronal differentiation. We studied the localization and function of LIMK2d isoform by transfecting Hela, NSC-34, and hippocampal rat neuron cultures. Similarly to LIMK2b, LIMK2d was expressed in the cytoplasm, neurites and dendritic spines, but not in the nucleus. Similarly to LIMK2a, LIMK2d over-expression in NSC-34 cells increased neurite length, but independently of cofilin phosphorylation or of direct interaction with actin. Overall, these results indicate that LIMK2d is a third LIMK2 isoform which regulates neurite extension and highlights the possible existence of a kinase independent function of LIMK2.
Collapse
|
16
|
Changes in hippocampal synapses and learning-memory abilities in a streptozotocin-treated rat model and intervention by using fasudil hydrochloride. Neuroscience 2012; 200:120-9. [DOI: 10.1016/j.neuroscience.2011.10.030] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Revised: 10/15/2011] [Accepted: 10/17/2011] [Indexed: 01/03/2023]
|
17
|
Lindström NO, Neves C, McIntosh R, Miedzybrodzka Z, Vargesson N, Collinson JM. Tissue specific characterisation of Lim-kinase 1 expression during mouse embryogenesis. Gene Expr Patterns 2010; 11:221-32. [PMID: 21167960 DOI: 10.1016/j.gep.2010.12.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 11/18/2010] [Accepted: 12/14/2010] [Indexed: 12/22/2022]
Abstract
The Lim-kinase (LIMK) proteins are important for the regulation of the actin cytoskeleton, in particular the control of actin nucleation and depolymerisation via regulation of cofilin, and hence may control a large number of processes during development, including cell tensegrity, migration, cell cycling, and axon guidance. LIMK1/LIMK2 knockouts disrupt spinal cord morphogenesis and synapse formation but other tissues and developmental processes that require LIMK are yet to be fully determined. To identify tissues and cell-types that may require LIMK, we characterised the pattern of LIMK1 protein during mouse embryogenesis. We showed that LIMK1 displays an expression pattern that is temporally dynamic and tissue-specific. In several tissues LIMK1 is detected in cell-types that also express Wilms' tumour protein 1 and that undergo transitions between epithelial and mesenchymal states, including the pleura, epicardium, kidney nephrons, and gonads. LIMK1 was also found in a subset of cells in the dorsal retina, and in mesenchymal cells surrounding the peripheral nerves. This detailed study of the spatial and temporal expression of LIMK1 shows that LIMK1 expression is more dynamic than previously reported, in particular at sites of tissue-tissue interactions guiding multiple developmental processes.
Collapse
Affiliation(s)
- Nils O Lindström
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK.
| | | | | | | | | | | |
Collapse
|
18
|
Ihnatovych I, Livak M, Reed J, de Lanerolle P, Strakova Z. Manipulating actin dynamics affects human in vitro decidualization. Biol Reprod 2009; 81:222-30. [PMID: 19339710 DOI: 10.1095/biolreprod.108.074666] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The differentiation of uterine stromal fibroblasts into decidual cells is critical for establishing pregnancy. This process, called decidualization, requires the reorganization of the actin cytoskeleton, which mainly depends on actin dynamics and the phosphorylation status of the myosin light chain. We manipulated actin dynamics with jasplakinolide (100 nM) and latrunculin B (1 microM), both of which significantly inhibited the synthesis of decidualization markers induced by 6 days of treatment with embryo-mimicking stimulus interleukin 1beta (IL1B) and steroid hormones (SHs; 17beta-estradiol and medroxyprogesterone acetate) in the human uterine fibroblast (HuF) in vitro model. However, only jasplakinolide had long-lasting effects on the G-actin:F-actin ratio and prevented decidualization induced by the artificial stimulus cAMP (and SHs). Actin-binding protein cofilin mainly colocalized with G-actin in the nucleus as well as the cytoplasm. Only some spots of colocalization between cofilin and F-actin were detected in the cytoplasm. Brief extraction of cytosolic proteins from living cells revealed that in cells treated with IL1B or cAMP (and SHs) for 6 days, cofilin was mainly detected in the nucleus. The translocation of cofilin from cytosol to nucleus was also detected in HuFs treated for 12 days with SHs, IL1B and SHs, and cAMP and SHs. The same significant translocation was confirmed in primary baboon stromal uterine fibroblasts. We conclude that changes in actin dynamics, particularly the stabilization of F-actin, have a significant negative impact on decidualization, and the translocation of cofilin to the nucleus is a key feature of this process in the primate.
Collapse
Affiliation(s)
- Ivanna Ihnatovych
- Department of Obstetrics and Gynecology, University of Illinois at Chicago, Chicago, Illinois 60612-7313, USA
| | | | | | | | | |
Collapse
|
19
|
Lin WH, Webb DJ. Actin and Actin-Binding Proteins: Masters of Dendritic Spine Formation, Morphology, and Function. THE OPEN NEUROSCIENCE JOURNAL 2009; 3:54-66. [PMID: 20717495 PMCID: PMC2921857 DOI: 10.2174/1874082000903020054] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dendritic spines are actin-rich protrusions that comprise the postsynaptic sites of synapses and receive the majority of excitatory synaptic inputs in the central nervous system. These structures are central to cognitive processes, and alterations in their number, size, and morphology are associated with many neurological disorders. Although the actin cytoskeleton is thought to govern spine formation, morphology, and synaptic functions, we are only beginning to understand how modulation of actin reorganization by actin-binding proteins (ABPs) contributes to the function of dendritic spines and synapses. In this review, we discuss what is currently known about the role of ABPs in regulating the formation, morphology, motility, and plasticity of dendritic spines and synapses.
Collapse
Affiliation(s)
- Wan-Hsin Lin
- Department of Biological Sciences and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Donna J. Webb
- Department of Biological Sciences and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
- Department of Cancer Biology, Vanderbilt University, Nashville, Tennessee 37235, USA
| |
Collapse
|
20
|
Ott EB, Te Velthuis AJW, Bagowski CP. Comparative analysis of splice form-specific expression of LIM Kinases during zebrafish development. Gene Expr Patterns 2007; 7:620-9. [PMID: 17300993 DOI: 10.1016/j.modgep.2006.12.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 12/19/2006] [Accepted: 12/20/2006] [Indexed: 12/21/2022]
Abstract
LIM Kinases (LIMK) are genes encoding multi-domain proteins that can contain up to two LIM domains, a single PDZ domain, and a tyrosine kinase domain. Alternative splicing is a source for different combinations of these domains. Two family members, LIMK1 and LIMK2 have been described in mammals and are important for organization of the actin cytoskeleton. We have cloned LIMK1 and LIMK2 from zebrafish and characterized their domain specific expression patterns during embryogenesis. The results on temporal and spatial expression of the LIM Kinases during embryogenesis indicate overlapping and distinct expression domains for LMK1 and LIMK2. Differences in expression during embryogenesis were observed for PDZ and LIM encoding splice forms for both LIM Kinases. To better understand the transcriptional regulation of LIM Kinases, we searched for conserved regulatory elements. We identified evolutionary conserved smad binding sites for LIMK2. In summary, we present here the splice-form specific temporal and spatial expression patterns for both LIMK1 and LIMK2 during zebrafish embryogenesis.
Collapse
Affiliation(s)
- Elisabeth B Ott
- Institute of Biology, Department of Integrative Zoology, University of Leiden, 2333 AL Leiden, The Netherlands
| | | | | |
Collapse
|
21
|
Scott RW, Olson MF. LIM kinases: function, regulation and association with human disease. J Mol Med (Berl) 2007; 85:555-68. [PMID: 17294230 DOI: 10.1007/s00109-007-0165-6] [Citation(s) in RCA: 240] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Revised: 12/15/2006] [Accepted: 12/27/2006] [Indexed: 12/20/2022]
Abstract
The LIM kinase family consists of just two members: LIM kinase 1 (LIMK1) and LIM kinase 2 (LIMK2). With uniquely organised signalling domains, LIM kinases are regulated by several upstream signalling pathways, principally acting downstream of Rho GTPases to influence the architecture of the actin cytoskeleton by regulating the activity of the cofilin family proteins cofilin1, cofilin2 and destrin. Although the LIM kinases are very homologous, particularly when comparing kinase domains, there is emerging evidence that each may be subject to different regulatory pathways and may contribute to both distinct and overlapping cellular and developmental functions. Normal central nervous system development is reliant upon the presence of LIMK1, and its deletion has been implicated in the development of the human genetic disorder Williams syndrome. Normal testis development, on the other hand, is disrupted by the deletion of LIMK2. In addition, the possible involvement of each kinase in cardiovascular disorders as well as cancer has recently emerged. The LIM kinases have been proposed to play an important role in tumour-cell invasion and metastasis; fine-tuning the balance between phosphorylated and non-phosphorylated cofilin may be a significant determinant of tumour-cell metastatic potential. In this review, we outline the structure, regulation and function of LIM kinases and their functions at cellular and organismal levels, as well as their possible contributions to human disease.
Collapse
Affiliation(s)
- Rebecca W Scott
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | | |
Collapse
|
22
|
Chen X, Macara IG. Par-3 mediates the inhibition of LIM kinase 2 to regulate cofilin phosphorylation and tight junction assembly. ACTA ACUST UNITED AC 2006; 172:671-8. [PMID: 16505165 PMCID: PMC2063700 DOI: 10.1083/jcb.200510061] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The polarity protein Par-3 plays critical roles in axon specification and the establishment of epithelial apico-basal polarity. Par-3 associates with Par-6 and atypical protein kinase C and is required for the proper assembly of tight junctions, but the molecular basis for its functions is poorly understood. We now report that depletion of Par-3 elevates the phosphorylated pool of cofilin, a key regulator of actin dynamics. Expression of a nonphosphorylatable mutant of cofilin partially rescues tight junction assembly in cells lacking Par-3, as does the depletion of LIM kinase 2 (LIMK2), an upstream kinase for cofilin. Par-3 binds to LIMK2 but not to the related kinase LIMK1. Par-3 inhibits LIMK2 activity in vitro, and overexpressed Par-3 suppresses cofilin phosphorylation that is induced by lysophosphatidic acid. Our findings identify LIMK2 as a novel target of Par-3 and uncover a molecular mechanism by which Par-3 could regulate actin dynamics during cell polarization.
Collapse
Affiliation(s)
- Xinyu Chen
- Center for Cell Signaling, Department of Microbiology, Health Sciences Center, University of Virginia, Charlottesville, VA 22908, USA.
| | | |
Collapse
|
23
|
Ang LH, Chen W, Yao Y, Ozawa R, Tao E, Yonekura J, Uemura T, Keshishian H, Hing H. Lim kinase regulates the development of olfactory and neuromuscular synapses. Dev Biol 2006; 293:178-90. [PMID: 16529736 DOI: 10.1016/j.ydbio.2006.01.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 01/25/2006] [Accepted: 01/30/2006] [Indexed: 12/20/2022]
Abstract
Lim Kinase (Limk) belongs to a phylogenetically conserved family of serine/threonine kinases, which have been shown to be potent regulators of the actin cytoskeleton. Despite accumulating evidence of its biochemical actions, its in vivo function has remained poorly understood. The association of the Limk1 gene with Williams Syndrome indicates that proteins of this family play a role in the nervous system. To unravel the cellular and molecular functions of Limk, we have either knocked out or activated the Limk gene in Drosophila. At the neuromuscular junction, loss of Limk leads to enlarged terminals, while increasing the activity of Limk leads to stunted terminals with fewer synaptic boutons. In the antennal lobe, loss of Limk abolishes the ability of p21-activated kinase (Pak) to alter glomerular development. In contrast, increase in Limk function leads to ectopic glomeruli, a phenotype suppressible by the coexpression of a hyperactive Cofilin gene. These results establish Limk as a critical regulator of Cofilin function and synapse development, and a downstream effector of Pak in vivo.
Collapse
Affiliation(s)
- Lay-Hong Ang
- Department of Cell and Developmental Biology and Neuroscience Program, University of Illinois at Urbana-Champaign, 601 South Goodwin Avenue, Urbana, IL 61801, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Acevedo K, Moussi N, Li R, Soo P, Bernard O. LIM kinase 2 is widely expressed in all tissues. J Histochem Cytochem 2006; 54:487-501. [PMID: 16399995 DOI: 10.1369/jhc.5c6813.2006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The LIM kinase family includes two proteins: LIMK1 and LIMK2. These proteins have identical genomic structure and overall amino acid identity of 50%. Both proteins regulate actin polymerization via phosphorylation and inactivation of the actin depolymerizing factors ADF/cofilin. Although the function of endogenous LIMK1 is well established, little is known about the function of the endogenous LIMK2 protein. To understand the specific role of endogenous LIMK2 protein, we examined its expression in embryonic and adult mice using a rat monoclonal antibody, which recognizes specifically the PDZ domain of LIMK2 but not that of LIMK1. Immunoblotting and immunoprecipitation analyses of mouse tissues and human and mouse cell lines revealed widespread expression of the 75-kDa LIMK2 protein. Immunofluorescence analysis demonstrated that the cellular localization of LIMK2 is different from that of LIMK1. LIMK2 protein is found in the cytoplasm localized to punctae and is not enriched within focal adhesions like LIMK1. Immunohistochemical studies revealed that LIMK2 is widely expressed in embryonic and adult mouse tissues and that its expression pattern is similar to that of LIMK1 except in the testes. We have also demonstrated that endogenous LIMK1 and LIMK2 form heterodimers, and that LIMK2 does not always interact with the same proteins as LIMK1.
Collapse
Affiliation(s)
- Karla Acevedo
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | | | | | | | | |
Collapse
|
25
|
Misra UK, Sharma T, Pizzo SV. Ligation of cell surface-associated glucose-regulated protein 78 by receptor-recognized forms of alpha 2-macroglobulin: activation of p21-activated protein kinase-2-dependent signaling in murine peritoneal macrophages. THE JOURNAL OF IMMUNOLOGY 2005; 175:2525-33. [PMID: 16081825 DOI: 10.4049/jimmunol.175.4.2525] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Previous studies of the plasma proteinase inhibitor alpha2-macroglobulin (alpha2M) demonstrated that alpha2M-proteinase complexes (alpha2M*) modulate immune responses and promotes macrophage locomotion and chemotaxis. Alpha2M* binds to cell surface-associated glucose-regulated protein 78 (GRP78), which activates downstream signaling events. The role of p21-activated protein kinase-1 and -2 (PAK-1 and -2) in promoting cellular motility is well documented. In the current study, we examined the ability of alpha2M* to activate PAK-1 and PAK-2. Upon macrophage stimulation with alpha2M*, PAK-2 is autophosphorylated, resulting in increased kinase activity; however, PAK-1 is negligibly affected. Alpha2M*-stimulated macrophages showed a marked elevation in the levels of Rac x GTP. Receptor tyrosine phosphorylation upon binding of alpha2M* to GRP78, recruits PAK-2 to the plasma membrane via the adaptor protein NCK. Consistent with this hypothesis, silencing of GRP78 gene expression greatly attenuated the levels of membrane-associated PAK-2 and NCK. PAK-2 activity was markedly decreased by inhibition of tyrosine kinases and PI3K before alpha2M* stimulation. We further demonstrate that phosphorylation of Lin-11, Isl-1, Mec-3 (LIM) kinase and cofilin is promoted by treating macrophages with alpha2M*. Thus, alpha2M* regulates activation of the PAK-2-dependent motility mechanism in these cells.
Collapse
Affiliation(s)
- Uma Kant Misra
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
| | | | | |
Collapse
|
26
|
Meng Y, Takahashi H, Meng J, Zhang Y, Lu G, Asrar S, Nakamura T, Jia Z. Regulation of ADF/cofilin phosphorylation and synaptic function by LIM-kinase. Neuropharmacology 2005; 47:746-54. [PMID: 15458846 DOI: 10.1016/j.neuropharm.2004.06.030] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Revised: 06/16/2004] [Accepted: 06/30/2004] [Indexed: 10/26/2022]
Abstract
To investigate the role of the LIM-kinase (LIMK) family in the regulation of ADF/cofilin phosphorylation and synaptic function in the mammalian central nervous system (CNS), we conducted biochemical and electrophysiological analysis using mice that were genetically altered in the expression of LIMK-1 and LIMK-2. We showed here that while LIMK-2 knockout mice exhibited minimal abnormalities, the LIMK-1/2 double knockout mice were more severely impaired in both ADF/cofilin phosphorylation and excitatory synaptic function in the CA1 region of the hippocampus. These results indicate a critical role for the LIMK family in the regulation of ADF/cofilin and synaptic function in the brain.
Collapse
Affiliation(s)
- Yanghong Meng
- Brain and Behavior, The Hospital for Sick Children, Room 6028, McMaster Building, Toronto, Ont. M5G 1X8, Canada
| | | | | | | | | | | | | | | |
Collapse
|
27
|
Lichtenbelt KD, Hochstenbach R, van Dam WM, Eleveld MJ, Poot M, Beemer FA. Supernumerary ring chromosome 7 mosaicism: Case report, investigation of the gene content, and delineation of the phenotype. Am J Med Genet A 2005; 132A:93-100. [PMID: 15580634 DOI: 10.1002/ajmg.a.30408] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We report a girl with severe retardation of expressive speech development carrying a small, supernumerary ring chromosome derived from the proximal region of the long arm of chromosome 7. The r(7) chromosome is present in 50% of lymphocytes. We also review the six additional cases with a supernumerary r(7) chromosome reported in the literature. Among these patients, a severe retardation of productive language capabilities is seen as a shared clinical feature, irrespective of the degree of mosaicism as detected in blood. The dysmorphisms in these patients are minor and no shared congenital abnormalities seen. We, therefore, recommend chromosomal investigations in children with unexplained, disproportionately retarded expressive speech performance. Because speech and language acquisition are subject to genetic influences, we investigated whether there are genes on the r(7) chromosome that may affect brain development or function in a dosage-dependent manner. We found that both in our patient and in four patients described by others, the supernumerary r(7) chromosome contains the region from the centromere up to marker D7S613 located at 7q11.23. We speculate that the effects on speech acquisition are mediated by the supernumerary copies of the STX1A and LIMK1 genes, which are both located in this region and known to suppress neurite growth when overexpressed in vitro.
Collapse
Affiliation(s)
- K D Lichtenbelt
- Department of Biomedical Genetics, University Medical Centre Utrecht, Utrecht, The Netherlands
| | | | | | | | | | | |
Collapse
|
28
|
Takahashi H, Funakoshi H, Nakamura T. LIM-kinase as a regulator of actin dynamics in spermatogenesis. Cytogenet Genome Res 2004; 103:290-8. [PMID: 15051950 DOI: 10.1159/000076815] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Accepted: 12/09/2003] [Indexed: 11/19/2022] Open
Abstract
We have identified LIM-kinase (LIMK1 and LIMK2), the only known catalytic protein among LIM-family molecules. Both LIMK1 and LIMK2 phosphorylate (inactivate) cofilin, an actin depolymerizing factor, and induce actin cytoskeleton reorganization. We as well as others concurrently demonstrated that LIMK activation was regulated by the Rho family of GTPases, and LIMK1 and LIMK2 share the distinct functional portion in Rho GTPases-mediated actin dynamics. Although evidence for their physiological significance is tenuous, several studies have focused on understanding LIMK functions, particularly in meiosis and mitosis. This review addresses recent LIMK findings, with emphasis on spermatogenesis studies, upon which future studies can shed light on the role of the LIMK/actin system in meiosis and mitosis.
Collapse
Affiliation(s)
- H Takahashi
- Division of Molecular Regenerative Medicine, Course of Advanced Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | | | | |
Collapse
|
29
|
Yang EJ, Yoon JH, Min DS, Chung KC. LIM Kinase 1 Activates cAMP-responsive Element-binding Protein during the Neuronal Differentiation of Immortalized Hippocampal Progenitor Cells. J Biol Chem 2004; 279:8903-10. [PMID: 14684741 DOI: 10.1074/jbc.m311913200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
LIM kinase 1 (LIMK1), a novel member of a subclass of the protein-serine/threonine kinases, is known to play a role in the development and maintenance of neuronal circuits that mediate cognitive function. Genetic studies have implicated a mutation of LIMK1 as a causative factor in the impairment of visuospatial cognition in a neurodevelopmental disorder, Williams syndrome. A transcriptional factor, cAMP-responsive element-binding protein (CREB), is thought to be involved in the formation of many types of synaptic plasticity involving learning and memory. In the present study we show that the LIMK1 activity is markedly induced during the differentiation of immortalized hippocampal progenitor (H19-7) cells. We found that the addition of neurogenic growth factor to H19-7 cells induces specific binding between LIMK1 and active CREB, that LIMK1 directly phosphorylates CREB, and that this leads to the stimulation of subsequent cAMP-responsive element-mediated gene transcription during H19-7 cell neuronal differentiation. In addition, we also found that LIMK1 activation occurs through Rac/Cdc42- and p21-activated kinase-mediated signaling pathways. Moreover, when the plasmid encoding kinase-inactive LIMK1 was transfected to block the activation of endogenous LIMK1, the neuronal differentiation of H19-7 cells was significantly suppressed. These findings suggest that LIMK1 activation and subsequent CREB phosphorylation are important in the neuronal differentiation of central nervous system hippocampal progenitor cells.
Collapse
Affiliation(s)
- Eun Jin Yang
- Department of Biology, College of Sciences, Yonsei University, Seoul 120-749, Korea
| | | | | | | |
Collapse
|
30
|
Ohta Y, Kousaka K, Nagata-Ohashi K, Ohashi K, Muramoto A, Shima Y, Niwa R, Uemura T, Mizuno K. Differential activities, subcellular distribution and tissue expression patterns of three members of Slingshot family phosphatases that dephosphorylate cofilin. Genes Cells 2003; 8:811-24. [PMID: 14531860 DOI: 10.1046/j.1365-2443.2003.00678.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Cofilin, a key regulator of actin filament dynamics, is inactivated by phosphorylation at Ser-3 by LIM-kinases and is reactivated by dephosphorylation by a family of protein phosphatases, termed Slingshot (SSH). RESULTS We have identified two novel isoforms of SSHs, termed SSH-2L and SSH-3L and characterized them in comparison with SSH-1L that was previously reported. SSH-1L and SSH-2L, but not SSH-3L, tightly bound to and co-localized with actin filaments. When expressed in cultured cells, SSH-1L, SSH-2L and SSH-3L decreased the level of Ser-3-phosphorylated cofilin (P-cofilin) in cells and suppressed LIM-kinase-induced actin reorganization, although SSH-3L was less effective than SSH-1L and SSH-2L. In cell-free assays, SSH-1L and SSH-2L efficiently dephosphorylated P-cofilin, whereas SSH-3L did do so only weakly. Using deleted mutants of SSH-1L and SSH-2L, we found that the N-terminal and C-terminal extracatalytic regions are critical for cofilin-phosphatase and F-actin-binding activities, respectively. In situ hybridization analyses revealed characteristic patterns of expression of each of the mouse Ssh genes in both neuronal and non-neuronal tissues; in particular, expression of Ssh-3 in epithelial tissues is evident. CONCLUSION SSH-1L, SSH-2L and SSH-3L have the potential to dephosphorylate P-cofilin, but subcellular distribution, F-actin-binding activity, specific phosphatase activity and expression patterns significantly differ, which suggests that they have related but distinct functions in various cellular and developmental events.
Collapse
Affiliation(s)
- Yusaku Ohta
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Control of growth cone motility and morphology by LIM kinase and Slingshot via phosphorylation and dephosphorylation of cofilin. J Neurosci 2003. [PMID: 12684437 DOI: 10.1523/jneurosci.23-07-02527.2003] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Growth cone motility and morphology are based on actin-filament dynamics. Cofilin plays an essential role for the rapid turnover of actin filaments by severing and depolymerizing them. The activity of cofilin is repressed by phosphorylation at Ser3 by LIM kinase (LIMK, in which LIM is an acronym of the three gene products Lin-11, Isl-1, and Mec-3) and is reactivated by dephosphorylation by phosphatases, termed Slingshot (SSH). We investigated the roles of cofilin, LIMK, and SSH in the growth cone motility and morphology and neurite extension by expressing fluorescence protein-labeled cofilin, LIMK1, SSH1, or their mutants in chick dorsal root ganglion (DRG) neurons and then monitoring live images of growth cones by time-lapse video fluorescence microscopy. The expression of LIMK1 remarkably repressed growth cone motility and neurite extension, whereas the expression of SSH1 or a nonphosphorylatable S3A mutant of cofilin enhanced these events. The fan-like shape of growth cones was disorganized by the expression of any of these proteins. The repressive effects on growth cone behavior by LIMK1 expression were significantly rescued by the coexpression of S3A-cofilin or SSH1. These findings suggest that LIMK1 and SSH1 play critical roles in controlling growth cone motility and morphology and neurite extension by regulating the activity of cofilin and may be involved in signaling pathways that regulate stimulus-induced growth cone guidance. Using various mutants of cofilin, we also obtained evidence that the actin-filament-severing activity of cofilin is critical for growth cone motility and neurite extension.
Collapse
|
32
|
Meng Y, Zhang Y, Tregoubov V, Janus C, Cruz L, Jackson M, Lu WY, MacDonald JF, Wang JY, Falls DL, Jia Z. Abnormal spine morphology and enhanced LTP in LIMK-1 knockout mice. Neuron 2002; 35:121-33. [PMID: 12123613 DOI: 10.1016/s0896-6273(02)00758-4] [Citation(s) in RCA: 498] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In vitro studies indicate a role for the LIM kinase family in the regulation of cofilin phosphorylation and actin dynamics. In addition, abnormal expression of LIMK-1 is associated with Williams syndrome, a mental disorder with profound deficits in visuospatial cognition. However, the in vivo function of this family of kinases remains elusive. Using LIMK-1 knockout mice, we demonstrate a significant role for LIMK-1 in vivo in regulating cofilin and the actin cytoskeleton. Furthermore, we show that the knockout mice exhibited significant abnormalities in spine morphology and in synaptic function, including enhanced hippocampal long-term potentiation. The knockout mice also showed altered fear responses and spatial learning. These results indicate that LIMK-1 plays a critical role in dendritic spine morphogenesis and brain function.
Collapse
Affiliation(s)
- Yanghong Meng
- Program in Brain and Behavior, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Abstract
Neurones are highly specialised cells that can extend over great distances, enabling the complex networking of the nervous system. We are beginning to understand in detail the molecular mechanisms that control the shape of neurones during development. One family of proteins that are clearly essential are the Rho GTPases which have a pivotal role in regulating the actin cytoskeleton in all cell types. The Rho GTPases are responsible for the activation and downregulation of many downstream kinases. This review discusses individual kinases that are regulated by three members of the Rho GTPases, Rac, Rho and Cdc42 and their function during neurite outgrowth and remodelling.
Collapse
Affiliation(s)
- Margareta Nikolic
- Molecular and Developmental Neurobiology MRC Centre, New Hunt's House, King's College London, London SE1 1UL, UK.
| |
Collapse
|
34
|
Takahashi H, Koshimizu U, Miyazaki JI, Nakamura T. Impaired spermatogenic ability of testicular germ cells in mice deficient in the LIM-kinase 2 gene. Dev Biol 2002; 241:259-72. [PMID: 11784110 DOI: 10.1006/dbio.2001.0512] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
LIM-Kinase (LIMK), including LIMK1 and LIMK2, is the only known catalytic protein among LIM-family molecules. It is well known that LIMK phosphorylates and inactivates cofilin, an actin-depolymerizing factor regulating actin reorganization, while in vivo functions have remained to be elucidated. In the present study, we generated Limk2 gene-deficient mice in which three LIMK2 isoforms were disrupted in a Cre-mediated fashion. Impaired cofilin phosphorylation was clearly observed in Limk2-/- fibroblasts stimulated with bradykinin or lysophosphatidic acid, thereby suggesting that Cdc42 or Rho-dependent LIMK activation did not occur. However, Limk2-/- mice did not exhibit embryonic lethality or any phenotypic abnormalities in postnatal growth and development, except for spermatogenesis in the testis. The testes of Limk2-/- mice were smaller in size and partial degeneration of spermatogenic cells in the seminiferous tubules was apparent in association with increased apoptosis. In addition, the viability of Limk2-/- spermatogenic cells, when cultured under stressed conditions, was diminished. Furthermore, the potential for germ cells to differentiate in a regenerative state was severely impaired in Limk2-/- testis. Experimental hyperthermia induced impairment of ADF/cofilin phosphorylation and the formation of intranuclear cofilin inclusions in mutant germ cells. Based on these findings, we propose that LIMK2, especially the testis-specific isoform tLIMK2, plays an important role in proper progression of spermatogenesis by regulation of cofilin activity and/or localization in germ cells.
Collapse
Affiliation(s)
- Hisaaki Takahashi
- Division of Molecular Regenerative Medicine, Course of Advanced Medicine B7, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | | | | | | |
Collapse
|
35
|
Balasubramaniam J, Del Bigio MR. Analysis of age-dependant alteration in the brain gene expression profile following induction of hydrocephalus in rats. Exp Neurol 2002; 173:105-13. [PMID: 11771943 DOI: 10.1006/exnr.2001.7831] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hydrocephalus is associated with gradual progressive impairment and destruction of cerebral axons and neurons. To provide a comprehensive analysis of gene expression changes in brain due to experimental hydrocephalus we used a DNA microarray screening technique. Hydrocephalus was induced in 3-week-old and 8- to 10-week-old rats by injection of kaolin into cisterna magna. Following induction of hydrocephalus, samples of frontoparietal cerebrum were studied 3 and 36 weeks later in young rats and 1.5 weeks later in adult rats. At the transcriptional level, young rats with subacute hydrocephalus showed overexpression of genes involved in synaptic transmission in parallel to genes associated with protective and compensatory mechanisms. Those with chronic hydrocephalus exhibited some similar changes among synapse-related genes but suppression of other neuronal genes. Expression of myelin-related genes was increased in both groups of rats with early onset hydrocephalus but suppressed in adult rats with acute hydrocephalus. Changes in genes related to extracellular matrix molecules suggest that there might be remodeling in this compartment. Adult rats showed elevated expression of inflammatory genes, likely related to kaolin-induced inflammation, but they failed to show changes in genes involved in compensatory or protective mechanisms. These results indicate that there is an age- and duration-dependent difference in the gene expression profiles of kaolin-induced hydrocephalus and they present avenues for future research.
Collapse
Affiliation(s)
- Janani Balasubramaniam
- Department of Pathology, University of Manitoba, Manitoba Institute for Child Health, Winnipeg, MB R3E 0W3 Canada
| | | |
Collapse
|
36
|
Takahashi T, Koshimizu U, Abe H, Obinata T, Nakamura T. Functional involvement of Xenopus LIM kinases in progression of oocyte maturation. Dev Biol 2001; 229:554-67. [PMID: 11150247 DOI: 10.1006/dbio.2000.9999] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
LIM kinases (LIMK), including LIMK1 and LIMK2, are unique LIM-family proteins containing a catalytic (kinase) domain. These kinases phosphorylate an actin-depolymerizing factor, cofilin, involved in the regulation of actin-filament dynamics. An unanswered question is the in vivo function of LIMK and how they contribute to development. When we cloned Xenopus homologues of mammalian LIMK, Xlimk1 and Xlimk2, we found that their mRNA and products were abundantly expressed in oocytes. In addition, we obtained evidence for the functional involvement of Xlimk1/2 during oocyte maturation. The microinjection of Xlimk1/2 mRNA into progesterone-treated oocytes significantly inhibited the appearance of a white maturation spot (WMS), an indicator of entry into meiosis. In oocytes lacking a WMS, the organization and/or migration of the microtubule-derived precursor of the meiotic spindle was predominantly affected. We also found that the ectopic expression of Xlimk1/2 clearly prevented dephosphorylation (activation) of Xenopus cofilin (XAC) during oocyte maturation. Furthermore, co-injection of Xlimk1/2 with the constitutively active type of XAC overcame the inhibitory effects by Xlimk1/2, suggesting that XLIMK-induced abnormality in oocyte maturation was mediated by XAC inactivation. Based on these findings, we propose that XLIMK is a putative regulator of cytoskeletal rearrangements during oocyte maturation, and the interaction between XLIMK activity and microtubule dynamics seems highly likely.
Collapse
Affiliation(s)
- T Takahashi
- Division of Biochemistry, Department of Oncology, Biomedical Research Center B7, Osaka University Medical School, Suita, Osaka, 565-0871, Japan
| | | | | | | | | |
Collapse
|
37
|
Sumi T, Matsumoto K, Nakamura T. Specific activation of LIM kinase 2 via phosphorylation of threonine 505 by ROCK, a Rho-dependent protein kinase. J Biol Chem 2001; 276:670-6. [PMID: 11018042 DOI: 10.1074/jbc.m007074200] [Citation(s) in RCA: 227] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
LIM-kinase 1 (LIMK1) and LIM-kinase 2 (LIMK2) regulate actin cytoskeletal reorganization via cofilin phosphorylation downstream of distinct Rho family GTPases. We report our findings that ROCK, a downstream protein kinase of Rho, specifically activates LIMK2 but not LIMK1 downstream of RhoA. LIMK1 and LIMK2 activities toward cofilin phosphorylation were stimulated by co-expression with the active form of ROCK (ROCK-Delta3), whereas full-length ROCK selectively activates LIMK2 but not LIMK1. Activation of LIMK2 by RhoA was inhibited by Y-27632, a specific inhibitor of ROCK, but Rac1-mediated activation of LIMK1 was not. ROCK directly phosphorylated the threonine 505 residue within the activation segment of LIMK2 and markedly stimulated LIMK2 activity. A LIMK2 mutant with replacement of threonine 505 by valine abolished LIMK2 activities for cofilin phosphorylation and actin cytoskeletal changes, whereas replacement by glutamate enhanced the protein kinase activity and stress fiber formation by LIMK2. These results indicate that ROCK directly phosphorylates threonine 505 and activates LIMK2 downstream of RhoA and that this phosphorylation is essential for LIMK2 to induce actin cytoskeletal reorganization. Together with the finding that LIMK1 is regulated by Pak1, LIMK1 and LIMK2 are regulated by different protein kinases downstream of distinct Rho family GTPases.
Collapse
Affiliation(s)
- T Sumi
- Division of Biochemistry, Department of Oncology, Biomedical Research Center, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | | | | |
Collapse
|
38
|
Abstract
LIM kinase 1 (LIMK1) is a cytoplasmic protein kinase that is highly expressed in neurons. In transfected cells, LIMK1 binds to the cytoplasmic tail of neuregulins and regulates the breakdown of actin filaments. To identify potential functions of LIMK1 in vivo, we have determined the subcellular distribution of LIMK1 protein within neurons of the rat by using immunomicroscopy. At neuromuscular synapses in the adult hindlimb, LIMK1 was concentrated in the presynaptic terminal. However, little LIMK1 immunoreactivity was detected at neuromuscular synapses before the 2nd week after birth, and most motoneuron terminals were not strongly LIMK1 immunoreactive until the 3rd week after birth. Thus, LIMK1 accumulation at neuromuscular synapses coincided with their maturation. In contrast, SV2, like many other presynaptic terminal proteins, can be readily detected at neuromuscular synapses in the embryo. Similar to its late accumulation at developing synapses, LIMK1 accumulation at regenerating neuromuscular synapses occurred long after these synapses first formed. In the adult ventral spinal cord, LIMK1 was concentrated in a subset of presynaptic terminals. LIMK1 gradually accumulated at spinal cord synapses postnatally, reaching adult levels only after P14. This study is the first to implicate LIMK1 in the function of presynaptic terminals. The concentration of LIMK1 in adult, but not nascent, presynaptic terminals suggests a role for this kinase in regulating the structural or functional characteristics of mature synapses.
Collapse
Affiliation(s)
- J Y Wang
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | | | | | | | | |
Collapse
|
39
|
Sumi T, Matsumoto K, Takai Y, Nakamura T. Cofilin phosphorylation and actin cytoskeletal dynamics regulated by rho- and Cdc42-activated LIM-kinase 2. J Cell Biol 1999; 147:1519-32. [PMID: 10613909 PMCID: PMC2174243 DOI: 10.1083/jcb.147.7.1519] [Citation(s) in RCA: 298] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The rapid turnover of actin filaments and the tertiary meshwork formation are regulated by a variety of actin-binding proteins. Protein phosphorylation of cofilin, an actin-binding protein that depolymerizes actin filaments, suppresses its function. Thus, cofilin is a terminal effector of signaling cascades that evokes actin cytoskeletal rearrangement. When wild-type LIMK2 and kinase-dead LIMK2 (LIMK2/KD) were respectively expressed in cells, LIMK2, but not LIMK2/KD, phosphorylated cofilin and induced formation of stress fibers and focal complexes. LIMK2 activity toward cofilin phosphorylation was stimulated by coexpression of activated Rho and Cdc42, but not Rac. Importantly, expression of activated Rho and Cdc42, respectively, induced stress fibers and filopodia, whereas both Rho- induced stress fibers and Cdc42-induced filopodia were abrogated by the coexpression of LIMK2/KD. In contrast, the coexpression of LIMK2/KD with the activated Rac did not affect Rac-induced lamellipodia formation. These results indicate that LIMK2 plays a crucial role both in Rho- and Cdc42-induced actin cytoskeletal reorganization, at least in part by inhibiting the functions of cofilin. Together with recent findings that LIMK1 participates in Rac-induced lamellipodia formation, LIMK1 and LIMK2 function under control of distinct Rho subfamily GTPases and are essential regulators in the Rho subfamilies-induced actin cytoskeletal reorganization.
Collapse
Affiliation(s)
| | | | - Yoshimi Takai
- Department of Molecular Biology and Biochemistry, Biomedical Research Center, Osaka University Medical School, Suita, Osaka 565-0871, Japan
| | | |
Collapse
|
40
|
Edwards DC, Gill GN. Structural features of LIM kinase that control effects on the actin cytoskeleton. J Biol Chem 1999; 274:11352-61. [PMID: 10196227 DOI: 10.1074/jbc.274.16.11352] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
LIM kinase phosphorylates and inactivates the actin binding/depolymerizing factor cofilin and induces actin cytoskeletal changes. Several unique structural features within LIM kinase were investigated for their roles in regulation of LIM kinase activity. Disruption of the second LIM domain or the PDZ domain or deletion of the entire amino terminus increased activity in vivo measured as increasing aggregation of the actin cytoskeleton. A kinase-deleted alternate splice product was identified and characterized. This alternate splice product and a kinase inactive mutant inhibited LIM kinase in vivo, indicating that the amino terminus suppresses activity of the kinase domain. Mutation of threonine 508 in the activation loop to valine abolished activity whereas replacement with 2 glutamic acid residues resulted in a fully active enzyme. Dephosphorylation of LIM kinase inhibited cofilin phosphorylation. Mutation of the basic insert in the activation loop inhibited activity in vivo, but not in vitro. These results indicate phosphorylation is an essential regulatory feature of LIM kinase and indicate that threonine 508 and the adjacent basic insert sequences of the activation loop are required for this process. A combination of structural features are thus involved in receiving upstream signals that regulate LIM kinase-induced actin cytoskeletal reorganization.
Collapse
Affiliation(s)
- D C Edwards
- Department of Chemistry, University of California San Diego, School of Medicine, La Jolla, California 92093, USA
| | | |
Collapse
|
41
|
Takahashi H, Koshimizu U, Nakamura T. A novel transcript encoding truncated LIM kinase 2 is specifically expressed in male germ cells undergoing meiosis. Biochem Biophys Res Commun 1998; 249:138-45. [PMID: 9705845 DOI: 10.1006/bbrc.1998.9094] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
LIM kinases, composed of LIMK1 and LIMK2, have unique structural features that contain two LIM motifs at the N-terminus and a catalytic domain at the C-terminus. We report evidence of a novel type of mouse LIMK2 (Limk2) transcript specifically expressed in testis. cDNA cloning showed this Limk2 variant, designated tLimk2, lacked LIM domains at the N-terminus, due to usage of a testis-specific, alternative initiation exon. In Northern blot analysis, tLimk2 was detected in intact adult testis, but not in germ-cell-deficient or immature testis, indicating the stage-specific expression of tLimk2 in spermatogenic cells. In situ hybridization clearly demonstrated that tLimk2 was restrictedly expressed in differentiated germ cells (pachytene spermatocytes to round spermatids) and not expressed in early stages of spermatogenic cells and somatic cells in testis. These results suggested the possibility that the tLimk2 product is involved in spermatogenesis, especially in meiotic and/or postmeiotic processes.
Collapse
Affiliation(s)
- H Takahashi
- Department of Oncology, Osaka University Medical School, Japan
| | | | | |
Collapse
|
42
|
Wang JY, Frenzel KE, Wen D, Falls DL. Transmembrane neuregulins interact with LIM kinase 1, a cytoplasmic protein kinase implicated in development of visuospatial cognition. J Biol Chem 1998; 273:20525-34. [PMID: 9685409 DOI: 10.1074/jbc.273.32.20525] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The neuregulins are receptor tyrosine kinase ligands that play a critical role in the development of the heart, nervous system, and breast. Unlike many extracellular signaling molecules, such as the neurotrophins, most neuregulins are synthesized as transmembrane proteins. To determine the functions of the highly conserved neuregulin cytoplasmic tail, a yeast two-hybrid screen was performed to identify proteins that interact with the 157-amino acid sequence common to the cytoplasmic tails of all transmembrane neuregulin isoforms. This screen revealed that the neuregulin cytoplasmic tail interacts with the LIM domain region of the nonreceptor protein kinase LIM kinase 1 (LIMK1). Interaction between the neuregulin cytoplasmic tail and full-length LIMK1 was demonstrated by in vitro binding and co-immunoprecipitation assays. Transmembrane neuregulins with each of the three known neuregulin cytoplasmic tail isoforms interacted with LIMK1. In contrast, the cytoplasmic tail of TGF-alpha did not interact with LIMK1. In vivo, neuregulin and LIMK1 are co-localized at the neuromuscular synapse, suggesting that LIMK1, like neuregulin, may play a role in synapse formation and maintenance. To our knowledge, LIMK1 is the first identified protein shown to interact with the cytoplasmic tail of a receptor tyrosine kinase ligand.
Collapse
Affiliation(s)
- J Y Wang
- Department of Biology, Emory University, Atlanta, Georgia 30322, USA
| | | | | | | |
Collapse
|
43
|
Yang N, Higuchi O, Mizuno K. Cytoplasmic localization of LIM-kinase 1 is directed by a short sequence within the PDZ domain. Exp Cell Res 1998; 241:242-52. [PMID: 9633533 DOI: 10.1006/excr.1998.4053] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
LIM-containing protein kinase 1 (LIMK1) is a serine/threonine kinase with a structure composed of two LIM domains, a PDZ domain, and a protein kinase domain. We examined the subcellular localization of LIMK1 and its variously deleted mutants in HeLa cells by transfection with these cDNAs. Immunofluorescence analysis revealed that the full-length LIMK1 and its mutants deleted with LIM domain or protein kinase domain preferentially localized in the cytoplasm, while the mutants deleted with the PDZ domain or a 52 amino acid region (B region) within the PDZ domain localized mainly in the nucleus. When the normally nuclear cyclin A was fused with the PDZ domain or the B region of LIMK1, it was localized in the cytoplasm of transfected cells. The corresponding region of the PDZ domain of postsynaptic density protein (PSD)-95 had no such function. Additionally, the PDZ domain of LIMK1 had no potential to bind to the C-terminal S/TXV peptides, to which the PSD-95 PDZ domain can bind. Taken together these results suggest that the PDZ domain, particularly the B region, of LIMK1 has a specific function to localize the protein in the cytoplasm. When glutathione S-transferase (GST) fused with the PDZ domain of LIMK1 (GST-PDZ) or GST-PDZ deleted with the B region (GST-PDZ delta B) was microinjected into the nucleus of COS cells, GST-PDZ was almost completely excluded from the nucleus within 30 min, whereas GST-PDZ delta B remained in the nucleus. These findings suggest that the B region of LIMK1 probably has nuclear export signal activity.
Collapse
Affiliation(s)
- N Yang
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
| | | | | |
Collapse
|
44
|
Ikebe C, Ohashi K, Mizuno K. Identification of testis-specific (Limk2t) and brain-specific (Limk2c) isoforms of mouse LIM-kinase 2 gene transcripts. Biochem Biophys Res Commun 1998; 246:307-12. [PMID: 9610354 DOI: 10.1006/bbrc.1998.8609] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
LIM-kinase 1 (LIMK1) and LIM-kinase 2 (LIMK2) are members of a novel serine/threonine kinase subfamily with structural features composed of N-terminal two LIM domains, an internal PDZ-like domain, and a C-terminal protein kinase domain. We recently identified and characterized the mouse Limk2 gene and two Limk2 transcripts (Limk2a and Limk2b) coding for proteins with distinct N-terminal LIM structures. Here we describe two additional transcripts of the mouse Limk2 gene. One is a 1.7-kb transcript, termed Limk2t, which is specifically expressed in the testis and codes for an N-terminally truncated form of LIMK2 consisting of only a part of a PDZ-like domain and a protein kinase domain. The other is a transcript, termed Limk2c, which is specifically expressed in the brain and codes for a protein with a 6-amino-acid insert within the protein kinase domain. Exons specific to the 5'-terminal extra sequence of Limk2t and the insert sequence of Limk2c locate between exons 5-6 and exons 8-9 in the mouse Limk2 gene, respectively. Testis- and brain-specific expression of Limk2t and Limk2c suggests specific roles in these tissues.
Collapse
Affiliation(s)
- C Ikebe
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
| | | | | |
Collapse
|
45
|
|