Project description:Establishment and maintenance of epithelial architecture are essential for embryonic development and adult physiology. Here, we show that ERK3, a poorly characterized atypical MAPK, regulates epithelial architecture in vertebrates. In Xenopus embryonic epidermal epithelia, ERK3 knockdown impairs adherens and tight junction protein distribution, as well as tight junction barrier function, resulting in epidermal breakdown. Moreover, in human breast epithelial cancer cells, inhibition of ERK3 expression induces thickened epithelia with aberrant adherens and tight junctions. Microarray results suggest an involvement of TFAP2A, a transcription factor important for epithelial gene expression, in ERK3-dependent gene expression changes. TFAP2A knockdown phenocopies ERK3 knockdown in both Xenopus embryos and human cells, and ERK3 is required for full activation of TFAP2A-dependent transcription. Our findings thus reveal that ERK3 regulates epithelial architecture, possibly in cooperation with TFAP2A. We used microarrays to study the changes in ERK3-dependent gene expression profiles during pronephros and epidermal development in Xenopus laevis embryos.
Project description:Establishment and maintenance of epithelial architecture are essential for embryonic development and adult physiology. Here, we show that ERK3, a poorly characterized atypical MAPK, regulates epithelial architecture in vertebrates. In Xenopus embryonic epidermal epithelia, ERK3 knockdown impairs adherens and tight junction protein distribution, as well as tight junction barrier function, resulting in epidermal breakdown. Moreover, in human breast epithelial cancer cells, inhibition of ERK3 expression induces thickened epithelia with aberrant adherens and tight junctions. Microarray results suggest an involvement of TFAP2A, a transcription factor important for epithelial gene expression, in ERK3-dependent gene expression changes. TFAP2A knockdown phenocopies ERK3 knockdown in both Xenopus embryos and human cells, and ERK3 is required for full activation of TFAP2A-dependent transcription. Our findings thus reveal that ERK3 regulates epithelial architecture, possibly in cooperation with TFAP2A. We used microarrays to compare the changes in ERK3-dependent gene expression profiles with those in TFAP2A-dependent gene expression profiles in Xenopus laevis embryos.
Project description:Epithelia contribute to physical barriers that protect internal tissues from the external environment and also support organ structure. Accordingly, establishment and maintenance of epithelial architecture are essential for both embryonic development and adult physiology. Here, using gene knockout and knockdown techniques along with gene profiling, we show that extracellular signal-regulated kinase 3 (ERK3), a poorly characterized atypical mitogen-activated protein kinase (MAPK), regulates the epithelial architecture in vertebrates. We found that in Xenopus embryonic epidermal epithelia, ERK3 knockdown impairs adherens and tight-junction protein distribution, as well as tight-junction barrier function, resulting in epidermal breakdown. Moreover, in human epithelial breast cancer cells, inhibition of ERK3 expression induced thickened epithelia with aberrant adherens and tight junctions. Results from microarray analyses suggested that transcription factor AP-2α (TFAP2A), a transcriptional regulator important for epithelial gene expression, is involved in ERK3-dependent changes in gene expression. Of note, TFAP2A knockdown phenocopied ERK3 knockdown in both Xenopus embryos and human cells, and ERK3 was required for full activation of TFAP2A-dependent transcription. Our findings reveal that ERK3 regulates epithelial architecture, possibly together with TFAP2A.
Project description:RNA sequencing analysis of control and ERK3 knockdown HCPECs was performed to understand the physiological relevance of ERK3 in maintaining basal as well as LPS-mediated innate immune responses in HCPECs. Results revealed that ERK3 is required for the regulation of several key cytokines and chemokines even at the steady state. In particular, we discovered that ERK3 is indespansable for the transcriptional regulation of CXCL8/IL-8, CXCL10, MCP-1/CCL2 and GCP-2/CXCL6. Concomitantly, a functional interpretation of the differentially expressed (DE) genes with topGO indicated an important role of ERK3 in regulation of genes involved in, among others, immune responses and leukocyte chemotaxis.
Project description:The physiological functions and downstream effectors of the atypical mitogen-activated protein kinase ERK3 remain to be characterized. We recently reported that mice expressing catalytically-inactive ERK3 (Mapk6KD/KD) exhibit a reduced post-natal growth rate as compared to control mice. Here, we show that genetic inactivation of ERK3 impairs post-natal skeletal muscle growth and adult muscle regeneration after injury. Loss of MK5 phenocopies the muscle phenotypes of Mapk6KD/KD mice. At the cellular level, genetic or pharmacological inactivation of ERK3 or MK5 induces precocious differentiation of C2C12 or primary myoblasts, concomitant with MyoD activation. Reciprocally, ectopic expression of activated MK5 inhibits myogenic differentiation. Mechanistically, we show that MK5 directly phosphorylates FoxO3, promoting its degradation and reducing its association with MyoD. Depletion of FoxO3 rescues in part the premature differentiation of C2C12 myoblasts observed upon inactivation of ERK3 or MK5. Our findings reveal that ERK3 and its substrate MK5 act in a linear signaling pathway to control post-natal myogenic differentiation.
Project description:Beta-adrenergic stimulation stabilizes ERK3, resulting in the formation of a complex with MK5 and thereby driving lipolysis. A downstream target of the complex is FOXO1, which controls expression of the lipolytic enzyme ATGL. Deletion of ERK3 in mouse adipocytes inhibits lipolysis, but elevates energy dissipation.
Project description:Extracellular signal-regulated kinase 3 (ERK3) is a poorly characterized member of the mitogen-activated protein (MAP) kinase family. Functional analysis of the ERK3 signaling pathway has been hampered by a lack of knowledge about the substrates and downstream effectors of the kinase. Here, we used large-scale quantitative phosphoproteomics and targeted gene silencing to identify direct ERK3 substrates and gain insight into its potential cellular functions. Detailed validation of one candidate substrate identified the gelsolin/villin family member supervillin (SVIL) as a bona fide ERK3 substrate. We show that ERK3 phosphorylates SVIL on Ser245 to regulate myosin II activation and cytokinetic furrowing in dividing cells. Depletion of SVIL or ERK3 leads to cytokinesis failure and multinucleation, a phenotype rescued by wild type SVIL but not by the non-phosphorylatable S245A mutant. Our results unveil a new function of the atypical MAP kinase ERK3 in cell division and the regulation of cell ploidy