The fidelity of sound transmission by cochlear implants in patients with sensorineural hearing loss could be greatly improved by increasing the number of frequency channels. This could be achieved by stimulating and guiding neurite outgrowth to reduce the distance between the implant's electrodes and the remnants of the spiral ganglion neurons. However, little is known about signaling pathways, besides those of neurotrophic factors, that are operational in the adult spiral ganglion. To systematically identify neuronal receptors for guidance cues in the adult cochlea, we conducted a genome-wide cDNA microarray screen with two-month-old CBA/CaJ mice. A meta-analysis of our data and those from older mice in two other studies revealed the presence of neuronal transmembrane receptors that represent all four established guidance pathwaysephrin, netrin, semaphorin, and slitin the mature cochlea as late as 15 months. In addition, we observed the expression of all known receptors for the Wnt morphogens, whose neuronal guidance function has only recently been recognized. In situ hybridizations located the mRNAs of the Wnt receptors frizzled 1, 4, 6, 9, and 10 specifically in adult spiral ganglion neurons. Finally, frizzled 9 protein was found in the growth cones of adult spiral ganglion neurons that were regenerating neurites in culture. We conclude from our results that adult spiral ganglion neurons are poised to respond to neurite damage, owing to the constitutive expression of a large and diverse collection of guidance receptors. Wnt signaling, in particular, emerges as a candidate pathway for guiding neurite outgrowth towards a cochlear implant after sensorineural hearing loss.
Expression of Wnt receptors in adult spiral ganglion neurons: frizzled 9 localization at growth cones of regenerating neurites.
Sex, Specimen part
View SamplesHuman neonates and older adults frequently exhibit a reduced capacity to control microbial infections. A variety of mechanisms involving both the innate and adaptive immune systems have been proposed to contribute to these deficiencies. The emergence of RNA sequencing (RNA-seq) as an accurate and quantitative method for examining mRNA levels provides an opportunity to compare transcriptional responses to a stimulus at a global scale in neonates, adults, and older adults. An examination of ex vivo monocyte responses to lipopolysaccharide stimulation or Listeria monocytogenes infection (with cord blood monocytes representing neonatal monocytes) revealed extensive similarities between all three age groups, with only a small number of genes exhibiting statistically significant differences. Using transcription factor motif analyses and RNA-seq data sets from a variety of mouse mutants, the most significant neonatal deficiencies corresponded to genes that require interferon response factor-3 or type 1 interferon signaling for their activation. In older adults, the most striking difference was broad, low-level activation of inflammatory genes prior to stimulation, consistent with prior evidence of a chronic inflammatory state in older adults. These results demonstrate the value of quantitative RNA-seq analyses and the feasibility of cross-species comparisons between well-defined mouse networks and human data sets. Overall design: RNA-seq of primary cells from three independent donors in three different age-groups across 3 time-points stimulated with either LPS or Listeria monocytogenes.
Age-Related Gene Expression Differences in Monocytes from Human Neonates, Young Adults, and Older Adults.
No sample metadata fields
View SamplesThe ubiquitously expressed G-protein-coupled receptor kinase 2 (GRK2, ADRBK1) is an indispensable kinase involved in growth, differentiation and development. Exaggerated GRK2 activity plays a major pathophysiological role in the development of cardiovascular diseases such as heart failure and hypertension. GRK2 exerts its functions by kinase-dependent and kinase-independent effects. To assess the differential impact of GRK2 on cellular signalling we established HEK cell clones with over-expression of comparable protein levels of GRK2 or the kinase-deficient GRK2-K220R mutant, respectively. HEK cells were either cultured in vitro or expanded in vivo, in immunodeficient NOD.Scid mice to discriminate between in vitro and in vivo effects of GRK2. Whole genome microarray gene expression profiling was performed of cultured HEK cells and of NOD.Scid mouse-expanded HEK clones. As an additional control, cells were re-cultured in vitro after expansion in NOD.Scid mice.
Inhibition of G-protein-coupled receptor kinase 2 (GRK2) triggers the growth-promoting mitogen-activated protein kinase (MAPK) pathway.
Specimen part
View SamplesThe Raf kinase inhibitor protein (RKIP) is a dual inhibitor of the Raf kinase and the G-protein-coupled receptor kinase 2 (GRK2). GRK2 is an indispensable kinase, which exerts a major role in the pathogenesis of heart failure, and inhibition of GRK2 is cardioprotective in experimental models of heart failure. To investigate the cardiac function of RKIP as GRK2 inhibitor, we generated transgenic mice with myocardium-specific expression of RKIP under control of the alpha-MHC promoter. For comparison, mice with myocardium-specific expression of a GRK-specific peptide inhibitor (GRK-Inh) were also generated. Two different transgenic mouse models were established. Transgenic RKIP mice and transgenic GRK-Inh mice were born at Mendelian frequencey and grew to adulthood normally.
Inhibition of G-protein-coupled receptor kinase 2 (GRK2) triggers the growth-promoting mitogen-activated protein kinase (MAPK) pathway.
Sex, Age, Specimen part
View SamplesThe transcription factor c-JUN and its upstream kinase JNK1 have been implicated in BCR-ABL induced leukemogenesis. JNK1 has been shown to regulate BCL2 expression thereby altering leukemogenesis, but the impact of c-JUN remained unclear. In this study we show that JNK1 and c-JUN promote leukemogenesis via separate pathways, since lack of c-JUN impairs proliferation of p185BCR-ABL transformed cells without affecting viability. The decreased proliferation of c-JunD/D cells is associated with the loss of cyclin dependent kinase 6 (CDK6) expression. In c-JunD/D cells CDK6 expression becomes down-regulated upon BCR-ABL induced transformation which correlates with CpG island methylation within the 5 region of Cdk6. We verified the impact of Cdk6 deficiency by using Cdk6-/- mice that developed BCR-ABL induced B-lymphoid leukemia with significantly increased latency and an attenuated disease phenotype. In addition we show that re-expression of CDK6 in BCR-ABL transformed c-JunD/D cells reconstitutes proliferation and tumor formation in Nu/Nu mice. In summary, our study reveals a novel function for the AP-1 transcription factor c-JUN in leukemogenesis by antagonizing promoter methylation. Moreover, we identify CDK6 as relevant and critical target of AP-1 regulated DNA methylation upon BCR-ABL induced transformation, thereby accelerating leukemogenesis.
c-JUN promotes BCR-ABL-induced lymphoid leukemia by inhibiting methylation of the 5' region of Cdk6.
Specimen part
View SamplesToxin A (TcdA) and Toxin B (TcdB), of the pathogen Clostridium difficile, are virulence factors that cause gross pathologic changes (e.g. inflammation, secretion, and diarrhea) in the infected host, yet the molecular and cellular pathways leading to observed host responses are poorly understood. To address this gap, TcdA and/or TcdB were injected into the ceca of mice and the genome-wide transcriptional response of epithelial layer cells was examined. Bioinformatic analysis of gene expression identified sets of cooperatively expressed genes. Further analysis of inflammation associated genes revealed dynamic chemokine responses.
In vivo physiological and transcriptional profiling reveals host responses to Clostridium difficile toxin A and toxin B.
No sample metadata fields
View SamplesMucolipidosis type II (MLII) is a severe inherited multisystemic disorder caused by mutations in the GNPTAB gene. Skeletal abnormalities are a predominant feature of MLII. Here we investigate the gene expression in a knock-in mouse model for mucolipidosis type II, generated by the insertion of a cytosine in the murine Gnptab gene (c.3082insC) that is homologous to a homozygous mutation in an MLII patient.
Decreased bone formation and increased osteoclastogenesis cause bone loss in mucolipidosis II.
Specimen part
View SamplesIn the following experiment, three different hESC cell lines (HES2, MEL1 and H9) were grown in the presence of KOSR, KOSR or mTESR containing media respectively. KOSR (Knockout serum replacement medium) is a standard media allowing the growth of hESC without the need for manual passaging - Enzymatic passaging is used instread. mTESR (Ludwig et al., 2007) is a media allowing the growth of hESC on matrigel with enzymatic passaging. At day 7 after passaging, these cells were FACs sorted for the presence of GCTM-2 and CD9 into 4 distinct fractions (p4: GCTM-2-neg, CD9-neg; p5: GCTM-2-low, CD9-low; p6: GCTM-2-medium, CD9-medium and p7: GCTM-2-high, CD9-high). For each cell line-subfraction combination, RNA was harvested and subject to microarray.
Identification of human embryonic stem cell surface markers by combined membrane-polysome translation state array analysis and immunotranscriptional profiling.
No sample metadata fields
View SamplesHES2 ESCs were grown in standard ES culture conditions. After 1 week, these cells were FACs sorted for the presence of GCTM-2 and CD9.
Identification of human embryonic stem cell surface markers by combined membrane-polysome translation state array analysis and immunotranscriptional profiling.
No sample metadata fields
View SamplesThe membrane fraction and the cytosolic fraction of HES2 cells were collected and subjected to microarray. The experiment was performed in triplicate
Identification of human embryonic stem cell surface markers by combined membrane-polysome translation state array analysis and immunotranscriptional profiling.
No sample metadata fields
View Samples