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HeLa cells: overexpression of importin alpha2

ABSTRACT: To test whether nuclear importin alpha2 can regulate transcription, we sought to examine gene expression changes in cells with nuclear accumulation of importin alpha2 by performing microarray analysis. We designed an experiment in which EGFP-fused full-length importin alpha2 was transfected into HeLa cells. To exclude the possibility that exogenous, full-length importin alpha2 protein enhances nuclear transport of karyophilic proteins such as transcription factors and thereby directly influences gene expression, a mutant of importin alpha2 which is mutated in the C-terminal CAS-binding domain was also transfected, so that it is never recycled to the cytoplasm and shows complete nuclear localization. We undertook to investigate whether there were changes in gene expression common to cells expressing the full-length importin alpha2 and the C-terminal mutant (C-mutant) isoform.

ORGANISM(S): Homo sapiens

PROVIDER: GSE25303 | GEO | 2010/11/24

SECONDARY ACCESSION(S): PRJNA134789

REPOSITORIES: GEO

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Project description:Introduction: The mechanisms governing synaptonuclear transport, and the transcriptional pathways that are at the core of neuronal disorders are poorly understood. The importin family of nuclear import factors has pivotal roles in such pathways, due to their involvement in intracellular transport from both synapse to soma and cytoplasm to nucleus. Mammals express six different isoforms of importin α, which bind an Importin β to form transport complexes for specific cargoes. Methods: We addressed the roles of importin α isoforms in mammalian CNS by evaluation of a systematic series of importin α knockout mice. A comprehensive battery of behavioral tests was used to investigate spontaneous and novelty-induced locomotion, basal ganglia function, motor coordination, neuromuscular integration, anxiety-related behaviors and memory. Subsequent analyses using acute-brain slice electrophysiology, RNA-seq, bioinformatics, imaging and pharmacology was used in order to delineate the contribution of genes and signaling pathways involved in the identified phenotype and screen for new therapeutic approaches. Results and Discussion: During the course of comprehensive behavioral profiling of importin α mouse mutants, we identified an importin α knockout (KO) mouse with significantly reduced anxiety levels. Electrophysiological recordings in acute hippocampal slices showed a reduced short-term and presynaptic plasticity (paired-pulse facilitation deficit, lower PTP), while LTP was not affected in these mutants. We then performed transcriptional profiling (RNA-seq) from hippocampal extracts of wild type versus mutant animals after exposure to an anxiogenic drug. Computational analysis revealed differences in the expression of genes and the involvement of transcription factors. Drugs that activate LXR or the Sphingosine 1 phosphate receptor have robust anxiolytic effects, while a Sphk1 blocker reverses anxiolysis in the importin α5 knockout mouse. Thus, importin α5 influences anxiety by regulating nuclear import in neurons.

Project description:Previous reports demonstrate that the Î±2-integrin (Î±2) mediates pancreatic ductal adenocarcinoma (PDAC) cell interaction with collagens. We found that untransformed pancreatic ductal epithelial cells and well-differentiated PDAC cells use Î±2 exclusively to adhere and migrate on collagenI. In contrast, poorly-differentiated PT45P1 and MIAPaCa2 cells demonstrate reduced reliance on, or complete loss of Î±2, respectively. Further, well-differentiated PDAC lines exhibit reduced in vitro invasion compared to poorly-differentiated lines, and Î±2-blockade suppressed invasion of well-differentiated lines exclusively. Based on these data and the demonstrated role of Î±2 in maintaining tissue architecture in other organs, we hypothesized that Î±2 may actually suppress the malignant phenotype in PDAC. Accordingly, stable ectopic expression of Î±2 in MIAPaCa2 cells (MP2-Î±2) retarded in vitro invasion. MP2-Î±2 cells maintained on collagenI were more invasion-retarded than MP2-Î±2 cells maintained in standard tissue culture, and demonstrated higher Î±2Î²1 expression that was reflected in faster and more complete adhesion/migration on collagenI. Affymetrix gene expression profiling of Î±2-expressing and mock-transfected cells revealed that kallikrein-related peptidases (KLK)-5, 6 and 7 were specifically upregulated by Î±2. Accordingly, well-differentiated PDAC lines express KLK-5, 6 and 7 and KLK blockade increased invasion as well as collagenI-migration in KLK-positive lines. Importantly, an Î±2 cytoplasmic deletion mutant promoted KLK expression and retarded invasion, while an Î±9Î±2 chimera retarded invasion less efficiently, and did not impact KLK expression. These data demonstrate for the first time that the Î±2-ectodomain and KLKâ??s coordinately regulate a less invasive phenotype in PDAC cells. Experiment Overall Design: Affymetrix global gene arrays were used to analyse differences in gene expression patterns in MIAPaCa2 cells stably reexpressing the alpha2 integrin, a cytoplasmic deletion of the alpha2 integrin (dCYTO) or an alpha9 ectodomain and transmembrane domain/alpha2 cytoplasmic domain chimera, versus vector-only mock controls. RNA was harvested from cells passaged identically and maitained under standard tissue culture conditions or on collagenI- or tenascin FNIII-coated plates.. Experiment Overall Design: Genetic manipulation (stable transgene expression)

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HeLa cells: overexpression of importin alpha2

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