LIM kinase 1, a key regulator of actin dynamics, is widely expressed in embryonic and adult tissues
ABSTRACT The expression of endogenous LIM kinase 1 (LIMK1) protein was investigated in embryonic and adult mice using a rat monoclonal antibody (mAb), which recognizes specifically the PDZ domain of LIMK1 and not LIMK2. Immunoblotting analysis revealed widespread expression of LIMK1 existing as a 70-kDa protein in tissues and in cell lines, with a higher mass form (approximately 75 kDa) present in some tissues and cell lines. Smaller isoforms of approximately 50 kDa were also occasionally evident. Immunofluorescence analysis demonstrated LIMK1 subcellular localization at focal adhesions in fibroblasts as revealed by co-staining with actin, paxillin and vinculin in addition to perinuclear (Golgi) and occasional nuclear localization. Furthermore, an association between LIMK1 and paxillin but not vinculin was identified by co-immunoprecipitation analysis. LIMK1 is enriched in both axonal and dendritic growth cones of E18 rat hippocampal pyramidal neurons where it is found in punctae that extend far out into filopodia, as well as in a perinuclear region identified as Golgi. In situ, we identify LIMK1 protein expression in all embryonic and adult tissues examined, albeit at different levels and in different cell populations. The rat monoclonal LIMK1 antibody recognizes proteins of similar size in cell and tissue extracts from numerous species. Thus, LIMK1 is a widely expressed protein that exists as several isoforms.
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- "De-epithelialization induced by cadherin-6B or BMP is mediated by the LIM kinase/cofilin pathway Non-canonical BMP signaling has been found to be transduced through several different mediators including LIM kinase 1 (LIMK1), Trb3 and Src, dependent on cellular context (Chan et al., 2007; Foletta et al., 2003; Hassel et al., 2004; Lee-Hoeflich et al., 2004; Miyazono et al., 2010; Wong et al., 2005). LIMK1 is expressed in most tissues of the developing embryo including the neural tube (Foletta et al., 2004). The activity of LIMK1 bound to cytoplasmic tail of BMP Type II receptor is regulated noncanonically by BMP (Foletta et al., 2003; Lee-Hoeflich et al., 2004) and the primary role of LIMK1 is to phosphorylate cofilin in order to regulate actin dynamics (Arber et al., 1998; Yang et al., 1998) as a mechanism to change cell morphology and/or migration . "
ABSTRACT: We previously provided evidence that cadherin-6B induces de-epithelialization of the neural crest prior to delamination and is required for the overall epithelial mesenchymal transition (EMT). Furthermore, de-epithelialization induced by cadherin-6B was found to be mediated by BMP receptor signaling independent of BMP. We now find that de-epithelialization is mediated by non-canonical BMP signaling through the BMP type II receptor (BMPRII) and not by canonical Smad dependent signaling through BMP Type I receptor. The LIM kinase/cofilin pathway mediates non-canonical BMPRII induced de-epithelialization, in response to either cadherin-6B or BMP. LIMK1 induces de-epithelialization in the neural tube and dominant negative LIMK1 decreases de-epithelialization induced by either cadherin-6B or BMP. Cofilin is the major known LIMK1 target and a S3A phosphorylation deficient mutated cofilin inhibits de-epithelialization induced by cadherin-6B as well as LIMK1. Importantly, LIMK1 as well as cadherin-6B can trigger ectopic delamination when co-expressed with the competence factor SOX9, showing that this cadherin-6B stimulated signaling pathway can mediate the full EMT in the appropriate context. These findings suggest that the de-epithelialization step of the neural crest EMT by cadherin-6B/BMPRII involves regulation of actin dynamics via LIMK/cofilin.Developmental Biology 04/2012; 366(2):232-43. DOI:10.1016/j.ydbio.2012.04.005 · 3.64 Impact Factor
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- "One factor implicated in regulating the axonal and dendritic outgrowth of neurons in vitro is the cytoplasmic kinase LIM kinase 1 (LIMK1) (Endo et al., 2003; Hsieh et al., 2006; Lee-Hoeflich et al., 2004; Mizuno et al., 1994; Rosso et al., 2004; Tursun et al., 2005). The LIMK1 and LIMK2 proteins are ubiquitously expressed, though LIMK1 is particularly enriched in the brain as well as in the growth cones of cultured neurons (Acevedo et al., 2006; Foletta et al., 2004; Piper et al., 2006; Rosso et al., 2004). LIMK1 directly impacts the assembly of actin filaments in response to modulation of its activity by extrinsic signals (Sarmiere and Bamburg, 2004; Takahashi et al., 2003). "
ABSTRACT: The actin cytoskeleton inside extending axonal and dendritic processes must undergo continuous assembly and disassembly. Some extrinsic factors modulate actin turnover through controlling the activity of LIM kinase 1 (LIMK1), which phosphorylates and inactivates the actin depolymerizing factor cofilin. Here, we for the first time examine the function and regulation of LIMK1 in vivo in the vertebrate nervous system. Upon expression of wildtype or kinase-dead forms of the protein, dendrite growth by Xenopus retinal ganglion cells (RGCs) was unchanged. In contrast, maintaining a low, but significant level, of LIMK1 function in the RGC axon is critical for proper extension. Interestingly, bone morphogenetic protein receptor II (BMPRII) is a major regulator of LIMK1 in extending RGC axons, as expression of a BMPRII lacking the LIMK1 binding region caused a dramatic shortening of the axons. Previously, we found that BMPRIIs stimulate dendrite initiation in vivo. Thus, the fact that manipulation of LIMK1 activity failed to alter dendrite growth suggests that BMPs may activate distinct signalling pathways in axons and dendrites.Developmental Biology 05/2009; 330(2):273-85. DOI:10.1016/j.ydbio.2009.03.027 · 3.64 Impact Factor
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- "In primary cultures of embryonic day 18 (E18) rat hippocampal pyramidal neurons, LIMK1 is found in axons and growth-cone filopodia. In the soma of these neurons , LIMK1 is found in the perinuclear region identified as cis-Golgi (Foletta et al. 2004; Rosso et al. 2004). However, little is known about the expression pattern and cellular localization of the LIMK2 protein. "
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.Journal of Histochemistry and Cytochemistry 06/2006; 54(5):487-501. DOI:10.1369/jhc.5C6813.2006 · 2.40 Impact Factor