NCBI Summary:
There are approximately 40 known eukaryotic LIM proteins, so named for the LIM domains they contain. LIM domains are highly conserved cysteine-rich structures containing 2 zinc fingers. Although zinc fingers usually function by binding to DNA or RNA, the LIM motif probably mediates protein-protein interactions. LIM kinase-1 and LIM kinase-2 belong to a small subfamily with a unique combination of 2 N-terminal LIM motifs and a C-terminal protein kinase domain. The protein encoded by this gene is phosphorylated and activated by ROCK, a downstream effector of Rho, and the encoded protein, in turn, phosphorylates cofilin, inhibiting its actin-depolymerizing activity. It is thought that this pathway contributes to Rho-induced reorganization of the actin cytoskeleton. At least three transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]
General function
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Cellular localization
Cytoplasmic
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Ovarian function
Early embryo development
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Expression regulated by
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Ovarian localization
Oocyte
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LIMK1/2 is required for actin filament and cell junction assembly in porcine embryos developing in vitro. Kwon J et al. (2020) This study was conducted to investigate the roles of LIM kinases (LIMK1 and LIMK2) during porcine early embryo development. We checked the mRNA expression patterns and localization of LIMK1/2 to evaluate their characterization. We further focused on exploring the function of LIMK1/2 in developmental competence and their relationship between actin assembly and cell junction integrity, specifically during the first cleavage and compaction. Pig ovaries were transferred from a local slaughterhouse within 1 h and cumulus oocyte complexes (COCs) were collected. COCs were matured in in vitro maturation medium in a CO2 incubator. Metaphase II oocytes were activated using an Electro Cell Manipulator 2001 and microinjected to insert LIMK1/2 dsRNA into the cytoplasm. To confirm the roles of LIMK1/2 during compaction and subsequent blastocyst formation, we employed a LIMK inhibitor (LIMKi3). LIMK1/2 was localized in cytoplasm in embryos and co-localized with actin in cell-to-cell boundaries after the morula stage. LIMK1/2 knockdown using LIMK1/2 dsRNA significantly decreased the cleavage rate, compared to the control group. Protein levels of E-cadherin and β-catenin, present in adherens junctions, were reduced at the cell-to-cell boundaries in the LIMK1/2 knockdown embryos. Embryos treated with LIMKi3 at the morula stage failed to undergo compaction and could not develop into blastocysts. Actin intensity at the cortical region was considerably reduced in LIMKi3-treated embryos. LIMKi3-induced decrease in cortical actin levels was attributed to the disruption of adherens junction and tight junction assembly. Phosphorylation of cofilin was also reduced in LIMKi3-treated embryos. The above results suggest that LIMK1/2 is crucial for cleavage and compaction through regulation of actin organization and cell junction assembly.//////////////////