Project description:In skeletal muscle differentiation, muscle-specific genes are regulated by two groups of transcription factors, the MyoD and MEF2 families, which work together to drive the differentiation process. Here we show that ERK5 regulates muscle cell fusion through Klf transcription factors. The inhibition of ERK5 activity suppresses muscle cell fusion with minimal effects on the expression of MyoD, MEF2, and their target genes. Promoter analysis coupled to microarray assay reveals that Klf-binding motifs are highly enriched in the promoter regions of ERK5-dependent upregulated genes. Remarkably, Klf2 and Klf4 expression are also upregulated during differentiation in an ERK5-dependent manner, and knockdown of Klf2 or Klf4 specifically suppresses muscle cell fusion. Moreover, we show that the Sp1 transcription factor links ERK5 to Klf2/4, and that nephronectin, a Klf transcriptional target, is involved in muscle cell fusion. Therefore, an ERK5/Sp1/Klf module plays a key role in the fusion process during skeletal muscle differentiation.
Project description:In skeletal muscle differentiation, muscle-specific genes are regulated by two groups of transcription factors, the MyoD and MEF2 families, which work together to drive the differentiation process. Here we show that ERK5 regulates muscle cell fusion through Klf transcription factors. The inhibition of ERK5 activity suppresses muscle cell fusion with minimal effects on the expression of MyoD, MEF2, and their target genes. Promoter analysis coupled to microarray assay reveals that Klf-binding motifs are highly enriched in the promoter regions of ERK5-dependent upregulated genes. Remarkably, Klf2 and Klf4 expression are also upregulated during differentiation in an ERK5-dependent manner, and knockdown of Klf2 or Klf4 specifically suppresses muscle cell fusion. Moreover, we show that the Sp1 transcription factor links ERK5 to Klf2/4, and that nephronectin, a Klf transcriptional target, is involved in muscle cell fusion. Therefore, an ERK5/Sp1/Klf module plays a key role in the fusion process during skeletal muscle differentiation. To identify those genes whose expression levels are regulated by the ERK5 pathway in differentiating C2C12 cells, we performed genome-wide analysis by using Affymetrix GeneChip oligonucleotide microarrays. We performed two independent experiments. For each experiment, we used five samples: cells in growth medium (0 day), lacZ-infected cells at two time points (2.5 days and 4.5 days of differentiation) and dnMEK5-infected cells at two time points (2.5 days and 4.5 days of differentiation). Each virus was infected at 1 day of differentiation. Total RNA was prepared using the RNeasy Mini Kit (Qiagen) according to the manufacturer’s instructions. The total RNA of each condition was obtained from two independent experiments. Synthesis of cDNA in vitro transcription and biotin labeling cRNA, and hybridization to the Mouse Genome 430 2.0 array (Affymetrix) were performed according to Affymetrix protocols. Hybridized arrays were scanned using an Affymetrix GeneChip Scanner. Scanned Chip images were analyzed with GeneChip operating Software v.1.4 (GCOS) and GeneSpring GX 11.0.2. (Agilent technologies).
Project description:Cancer cell motility and invasiveness are fundamental characteristics of the malignant phenotype and are regulated through diverse signaling networks involving kinases and transcription factors. In this study, we identify a nuclear hormone receptor (ERα)-protein kinase (ERK5)-cofilin (CFL1) network that specifies the degree of breast cancer cell aggressiveness through coupling of actin reorganization and hormone receptor-mediated transcription. Using dominant negative and constitutively active forms, as well as small molecule inhibitors of ERK5 and MEK5, we show that hormone activation of estrogen receptor-α determines the nuclear versus cytoplasmic localization of the MAPK family member ERK5, which functions as a coregulator of ERα-gene transcription. Notably, ERK5 works with the actin remodeling protein, CFL1, and upon hormone exposure both became localized to transcription factories in the nucleus, verified by immunofluorescence and proximity ligation assays. Both factors facilitated PAF1 recruitment to the RNA Pol II complex and both ERK5 and CFL1 were required for regulation of gene transcription. By contrast, in cells lacking ERα, ERK5 and CFL1 localized to cytoplasmic membrane regions of high actin remodeling, promoting cell motility and invasion, thereby revealing a mechanism likely to contribute to the generally poorer prognosis of ERα-negative breast cancers. Our study uncovers the dynamic interplay of nuclear receptor-mediated transcription and actin reorganization in phenotypes of breast cancer aggressiveness, and highlights new prognostic biomarkers and suggests novel approaches for developing targeted therapies to moderate cancer aggressiveness. MCF-7 human breast adenocarcinoma cells were tranfected with control, and ERK5 siRNA for 72 hours and treated with 0.1% EtOH (Vehicle) or 10 nM E2 for 24 hours, and cDNA microarray analyses were carried out using Affymetrix [HG-U133A_2] Affymetrix Human Genome U133A 2.0 Array. siRNA knock-down, ligand treatment
Project description:Cancer cell motility and invasiveness are fundamental characteristics of the malignant phenotype and are regulated through diverse signaling networks involving kinases and transcription factors. In this study, we identify a nuclear hormone receptor (ERα)-protein kinase (ERK5)-cofilin (CFL1) network that specifies the degree of breast cancer cell aggressiveness through coupling of actin reorganization and hormone receptor-mediated transcription. Using dominant negative and constitutively active forms, as well as small molecule inhibitors of ERK5 and MEK5, we show that hormone activation of estrogen receptor-α determines the nuclear versus cytoplasmic localization of the MAPK family member ERK5, which functions as a coregulator of ERα-gene transcription. Notably, ERK5 works with the actin remodeling protein, CFL1, and upon hormone exposure both became localized to transcription factories in the nucleus, verified by immunofluorescence and proximity ligation assays. Both factors facilitated PAF1 recruitment to the RNA Pol II complex and both ERK5 and CFL1 were required for regulation of gene transcription. By contrast, in cells lacking ERα, ERK5 and CFL1 localized to cytoplasmic membrane regions of high actin remodeling, promoting cell motility and invasion, thereby revealing a mechanism likely to contribute to the generally poorer prognosis of ERα-negative breast cancers. Our study uncovers the dynamic interplay of nuclear receptor-mediated transcription and actin reorganization in phenotypes of breast cancer aggressiveness, and highlights new prognostic biomarkers and suggests novel approaches for developing targeted therapies to moderate cancer aggressiveness.
Project description:Depletion of ERK5 expression using the CRISPR/Cas9 system in MDA-MB-231 and Hs-578T cells resulted in loss of mesenchymal features, as observed through gene expression profile and cell morphology, and suppressed TNBC cell migration. In vivo xenograft experiments revealed ERK5 knockout disrupted tumor growth kinetics, which was restored using high concentration MatrigelTM and ERK5-ko reduced expression of the angiogenesis marker CD31. These findings implicated a role for ERK5 in the extracellular matrix (ECM) and matrix integrity. RNA-sequencing analyses demonstrated downregulation of extracellular matrix (ECM), integrin, and pro-angiogenic factors in ERK5-ko cells. Tissue decellularization combined with cryo-SEM and interrogation of biomechanical properties revealed that ERK5-ko results in loss of key ECM fiber alignment and mechanosensing capabilities in breast cancer xenografts compared to parental wild-type cells. In this study, we identified a novel role for ERK5 in tumor growth kinetics through modulation of the ECM and angiogenesis axis in breast cancer.
Project description:This experiment is part of the FunGenES project (FunGenES - Functional Genomics in Embryonic Stem Cells partially funded by the 6th Framework Programme of the European Union, http://www.fungenes.org). The experiment was conducted at Inserm U846, Bron, France. Aim: Kru_ppel-like factors (Klf) 4 and 5 are two closely related members of the Klf family, known to play key roles in somatic cell reprogramming and in self-renewal of pluripotent stem cells. In this study, we focused on the functional divergence between Klf4 and Klf5. We showed that Klf4 and Klf5 regulate the expression of distinct subsets of genes. Klf4 negatively regulates the expression of endodermal markers, some of which encode transcription factors involved in the commitment of pluripotent system cells to endoderm differentiation. In contrast, Klf5 negatively regulates the expression of mesodermal markers, some of which controls commitment to the mesoderm lineage. Functional studies with reporter cell lines indicate that knockdown of Klf4 enhances differentiation toward visceral endoderm, mesendoderm, and definitive endoderm, whereas knockdown of Klf5 specifically enhances differentiation toward mesoderm. Thus, additive functions of Klf4 and Klf5 secure pluripotent stem cell propagation by inhibiting endoderm and mesoderm differentiation.