The signaling pathways that commit cells to migration are incompletely understood. We employed human mammary cells and two stimuli: epidermal growth factor (EGF), which induced cellular migration, and serum factors, which stimulated cell growth. In addition to strong activation of ERK by EGF, and AKT by serum, early transcription remarkably differed: while EGF induced early growth response-1 (EGR1), and this was required for migration, serum induced c-Fos and FosB to enhance proliferation. We demonstrate that induction of EGR1 involves ERK-mediated down-regulation of microRNA-191 and phosphorylation of the ETS2 repressor factor (ERF) repressor, which subsequently leaves the nucleus. Unexpectedly, knockdown of ERF inhibited migration, which implies migratory roles for exported ERF molecules. On the other hand, chromatin immunoprecipitation identified a subset of direct EGR1 targets, including EGR1 autostimulation and SERPINB2, whose transcription is essential for EGF-induced cell migration. In summary, EGR1 and the EGF-ERK-ERF axis emerge from our study as major drivers of growth factor-induced mammary cell migration.
"sessed in wound - healing and transwell migration assays ( Fig . 2A - C ) , respectively . These results suggest that Nir2 plays an important role in the migratory responses of MCF10A cells . Previous studies suggested that the migratory response to EGF and TGFb in MCF10A cells are mediated , mainly , through the ERK pathway ( Kim et al . , 2004 ; Tarcic et al . , 2012 ) . We , therefore , examined the effects of Nir2 on ERK1 / 2 phosphorylation . As shown , overexpression of Nir2 in MCF10A cells enhanced the phosphorylation of ERK1 / 2 ( Fig . 2D ) , whereas Nir2 depletion reduced ERK1 / 2 phosphorylation in response to either EGF or TGFb ( Fig . 2D ; supplementary material Fig . S2B ) , consistent w"
[Show abstract][Hide abstract] ABSTRACT: The involvement of Epithelial-mesenchymal transition (EMT) in breast cancer metastasis has been demonstrated by many studies. However, the intracellular proteins and signaling pathways that regulate EMT have not been fully identified. Here we show that the lipid-transfer protein Nir2 enhances EMT in mammary epithelial and breast cancer cells. Nir2 overexpression induces down-regulation of epithelial markers and concomitant up-regulation of mesenchymal markers, while silencing of Nir2 by shRNA has opposite effects. Additionally, Nir2 expression is increased during EMT and affects cell morphology, while Nir2 depletion attenuates growth factor-induced cell migration. These effects of Nir2 on EMT-associated processes are mainly mediated through the PI3K/AKT and the ERK1/2 pathways. Nir2 depletion also inhibits cell invasion in vitro and lung metastasis in animal models. Immunohistochemical analysis of breast cancer tissue samples reveals a correlation between high Nir2 expression and tumor grade, and Kaplan-Meier survival curves correlate Nir2 expression with poor disease outcome. These results suggest that Nir2 not only enhances EMT in vitro and breast cancer metastasis in animal models, but also contributes to breast cancer progression in human patients.
"DEVELOPMENT normal heads with proper brains. Given that EGFR/ERK signaling regulates egr genes in several other contexts (Mayer et al., 2009; Harada et al., 2001; Tarcic et al., 2012; Mukhopadhyay et al., 2013), planarians provide a unique opportunity with which to study the function of this conserved pathway during regeneration. A recent study proposed that during planarian regeneration neoblasts follow a default program, triggered by ERK activation, to differentiate into head tissues (Umesono et al., 2013). "
[Show abstract][Hide abstract] ABSTRACT: During the regeneration of freshwater planarians, polarity and patterning programs play essential roles in determining whether a head or a tail regenerates at anterior or posterior-facing wounds. This decision is made very soon after amputation. The pivotal role of the Wnt/β-catenin and Hh signaling pathways in re-establishing anterior-posterior (AP) polarity has been well documented. However, the mechanisms that control the growth and differentiation of the blastema in accordance with its AP identity are less well understood. Previous studies have described a role of Smed-egfr-3, a planarian epidermal growth factor receptor, in blastema growth and differentiation. Here, we identify Smed-egr-4, a zinc-finger transcription factor belonging to the early growth response gene family, as a putative downstream target of Smed-egfr-3. Smed-egr-4 is mainly expressed in the central nervous system and its silencing inhibits anterior regeneration without affecting the regeneration of posterior regions. Single and combinatorial RNA interference to target different elements of the Wnt/β-catenin pathway, together with expression analysis of brain- and anterior-specific markers, revealed that Smed-egr-4: (1) is expressed in two phases - an early Smed-egfr-3-independent phase and a late Smed-egfr-3-dependent phase; (2) is necessary for the differentiation of the brain primordia in the early stages of regeneration; and (3) that it appears to antagonize the activity of the Wnt/β-catenin pathway to allow head regeneration. These results suggest that a conserved EGFR/egr pathway plays an important role in cell differentiation during planarian regeneration and indicate an association between early brain differentiation and the proper progression of head regeneration.
Development 04/2014; 141(9). DOI:10.1242/dev.101345 · 6.46 Impact Factor
"To characterize signal-induced TIV, we used MCF10A mammary cells, which migrate in response to EGF stimulus , , . Starved MCF10A cells were stimulated with EGF, total RNA was isolated from biological triplicates at seven time points, and samples were individually hybridized to exon arrays (Figure 1A). "
[Show abstract][Hide abstract] ABSTRACT: Signal-induced transcript isoform variation (TIV) includes alternative promoter usage as well as alternative splicing and alternative polyadenylation of mRNA. To assess the phenotypic relevance of signal-induced TIV, we employed exon arrays and breast epithelial cells, which migrate in response to the epidermal growth factor (EGF). We show that EGF rapidly - within one hour - induces widespread TIV in a significant fraction of the transcriptome. Importantly, TIV characterizes many genes that display no differential expression upon stimulus. In addition, similar EGF-dependent changes are shared by a panel of mammary cell lines. A functional screen, which utilized isoform-specific siRNA oligonucleotides, indicated that several isoforms play essential, non-redundant roles in EGF-induced mammary cell migration. Taken together, our findings highlight the importance of TIV in the rapid evolvement of a phenotypic response to extracellular signals.
PLoS ONE 12/2013; 8(12):e80566. DOI:10.1371/journal.pone.0080566 · 3.23 Impact Factor
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