The full complement of molecular pathways contributing to Parkinsons disease (PD) pathogenesis remains unknown. Here, to address this issue, we began by using a high-resolution variant of functional magnetic resonance imaging (fMRI) to pinpoint brainstem regions differentially affected by, and resistant to, the disease. Then, relying on the imaging information as a guide, we profiled gene expression levels of postmortem brain samples and used a factorial statistical model to identify a disease related decrease in the expression of the polyamine enzyme spermidine/spermine N1-acetyltransferase 1 (SAT1). Next, a series of studies were performed to confirm the pathogenic relevance of this finding. First, to test for a causal link between polyamines and -synuclein toxicity, we investigated a yeast model expressing -synuclein. Polyamines were found to enhance the toxicity of -synuclein, and an unbiased genome-wide screen for modifiers of -synuclein toxicity identified Tpo4, a member of a family of proteins responsible for polyamine transport. Second, to test for a causal link between SAT1 activity and PD histopathology we investigated a mouse model expressing -synuclein. DENSPM (N1, N11-diethylnorspermine), a polyamine analog that increases SAT1 activity, was found to reduce PD histopathology, while Berenil (diminazene aceturate), a pharmacological agent that reduces SAT1 activity, worsened the histopathology. Third, we genotyped PD patients and controls and isolated a rare but novel variant in the SAT1 gene, although the functional significance of this genetic variant was not identified. Taken together, the results suggest that the polyamine pathway contributes to PD pathogenesis.
Polyamine pathway contributes to the pathogenesis of Parkinson disease.
Sex, Age, Subject
View SamplesProtective interactions with bystander cells in micro-environmental niches such as lymph nodes (LNs) contribute to survival and therapy resistance of chronic lymphocytic leukemia (CLL) cells. This is caused by a shift in expression of BCL-2 family members. Pro-survival proteins BCL-XL, BFL-1, and MCL-1 are upregulated by LN-residing T cells through CD40L interaction, presumably via NF-B signaling. Macrophages also reside in the LN, and are assumed to provide important supportive functions for CLL cells. However, if and how macrophages are able to induce survival is incompletely known. We first established that macrophages induced survival due to an exclusive upregulation of MCL-1. Next, we investigated the mechanism underlying MCL-1 induction by macrophages in comparison with CD40L. Genome-wide expression profiling of in vitro macrophage- and CD40L-stimulated CLL cells indicated activation of the PI3K-AKT-mTOR pathway, which was confirmed in ex vivo CLL LN material. Inhibition of PI3K-AKT-mTOR signaling abrogated MCL-1 upregulation and survival by macrophages as well asCD40 stimulation. MCL-1 can be regulated at multiple levels, and we established that AKT leads to increased MCL-1 translation, but does not affect MCL-1 transcription or protein stabilization. Furthermore, among macrophage-secreted factors that could activate AKT, we found that induction of MCL-1 and survival critically depended on C-C Motif Chemokine Receptor-1 (CCR1). In conclusion, this study indicates that two distinct micro-environmental factors, CD40L and macrophages, signal via CCR1 to induce AKT activation resulting in translational stabilization of MCL-1, and hence can contribute to CLL cell survival.
Macrophages confer survival signals via CCR1-dependent translational MCL-1 induction in chronic lymphocytic leukemia.
Specimen part, Disease stage
View SamplesMost kidney allograft losses are caused by chronic allograft dysfunction (CAD) that is characterized by interstitial fibrosis, tubular atrophy and a smoldering inflammatory process. The aim of the study was to correlate changes in gene expression over time, as evidenced by effects on regulatory pathways linked to the development of fibrosis and inflammation during the development of chronic damage. Renal allografts were harvested for time points 0d, 7d, 14d and 56d (n=3-5) and examined for steady state mRNA expression using Affymetrix microarray RG-U34A. A select group of genes previously associated with chronic fibrosis was then examined in the context of progressive dysfunction. In order to verify the microarray analysis, qPCR has been performed.
Wnt pathway regulation in chronic renal allograft damage.
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View SamplesRed blood cells (RBCs) mature within a specialized niche (the erythroblastic island (EI)), which consists of a central macrophage surrounded by differentiating erythroblasts. Human Induced Pluripotent Stem Cell derived macrophages (iPSC-DMs) enhance proliferation and terminal maturation of Umbilical Cord Blood (UCB) CD34+ derived erythroid cells and iPSC derived erythroid cells. These effects are further increased when an inducible KLF1-ERT2 fusion protein is activated in iPSC-DMs. To assess the mechanism of action, we sought to compare the transcriptome of iPSC-DMs with and without KLF1 activation. For this, we used an inducible IPSC line (iKLF1.2) in which upon tamoxifen addition, the KLF1 transcription factor is translocated to nucleus and consequently KLF1 downstream targets are expressed. The identification and characterisation of could identify factors involved in erythroid maturation and thus helpful to improve current protocols to manufacture RBCs in vitro. Overall design: iKLF1.2 iPSCs were differentiated to macrophages and then split into 2 groups, one was treated with tamoxifen for the last 4 days of culture to activate KLF1. The other group was not treated with tamoxifen. Four biologically independent differentiation experiments were carried out and so 8 samples were generated: 4 samples of untreated iKLF1.2 iPSCs-derived macrophages and 4 samples of tamoxifen treated iKLF1.2 iPSC-derived macrophages. Total RNA was extracted from each sample and RNA integrity was of a high enough quality for library preparation, as all RIN values were above 9 for every sample.
Genetic programming of macrophages generates an in vitro model for the human erythroid island niche.
Specimen part, Treatment, Subject
View SamplesWe performed microarray analysis to investigate the gene expression profile changes induced by Hmg20b knock down in I/11 cells.
The DNA binding factor Hmg20b is a repressor of erythroid differentiation.
Specimen part
View SamplesTo identify cellular and genetic abnormalities involved in interstrand cross link repair-deficient bone marrow failure and its transformation to leukemia, we used an Ercc1 hypomorphic mouse model (Ercc1 -/d).
ICL-induced miR139-3p and miR199a-3p have opposite roles in hematopoietic cell expansion and leukemic transformation.
Age, Specimen part
View SamplesTumor metastasis and lack of NKG2D ligand (NKG2DL) expression are associated with poor prognosis in patients with colon cancer. Here we found that spironolactone (SPIR), an FDA-approved diuretic drug with a long-term safety profile, can upregulate NKG2DL expression in multiple colon cancer cell lines by activating the ATM-Chk2-mediated checkpoint pathway, which in turn enhances tumor elimination by natural killer cells. SPIR can also upregulate the expression of metastasis-suppressor genes TIMP2 and TIMP3, thereby reducing tumor cell invasiveness. Although SPIR is an aldosterone antagonist, its anti-tumor effects are independent of the mineralocorticoid receptor pathway. Instead, by screening the human nuclear hormone receptor siRNA library, we identify retinoid X receptor gamma (RXR gamma) as being indispensable for the anti-tumor functions of SPIR. Collectively, our results strongly support the use of SPIR or other RXR gamma-agonists with minimal side effects for colon cancer prevention and therapy.
Modulation of NKG2D ligand expression and metastasis in tumors by spironolactone via RXRγ activation.
Treatment
View SamplesHereditary Persistence of Fetal Hemoglobin (HPFH) is characterized by persistent high levels of fetal hemoglobin (HbF) in adults. Several contributory factors, both genetic and environmental, have been identified, but others remain elusive. Ten of twenty-seven members from a Maltese family presented with HPFH. A genome-wide SNP scan followed by linkage analysis revealed a candidate region on chromosome 19p13.12-13. Sequencing identified a nonsense mutation in the KLF1 gene, p.K288X, ablating the DNA binding domain of this key erythroid transcriptional regulator. Only HPFH family members were heterozygote carriers of this mutation. Expression profiling on primary erythroid progenitors revealed down-regulation of KLF1 target genes in HPFH samples. Functional assays demonstrated that, in addition to its established role in adult globin expression, KLF1 is a critical activator of the BCL11A gene, encoding a suppressor of HbF expression. These observations provide a rationale for the effects of KLF1 haploinsufficiency on HbF levels. To identify differentially expressed genes, RNA was isolated from erythroid progenitors (HEPs) cultured from peripheral blood of four HPFH (KLF1 p.K288X/wt) and four non-HPFH family members (wt/wt) and used for genome-wide expression analysis.
Haploinsufficiency for the erythroid transcription factor KLF1 causes hereditary persistence of fetal hemoglobin.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Pi3kcb links Hippo-YAP and PI3K-AKT signaling pathways to promote cardiomyocyte proliferation and survival.
Specimen part
View SamplesBackgroundYAP, the nuclear effector of Hippo signaling, regulates cellular growth and survival in multiple organs, including the heart, by interacting with TEAD sequence specific DNA-binding proteins. Recent studies showed that YAP stimulates cardiomyocyte proliferation and survival. However, the direct transcriptional targets through which YAP exerts its effects are poorly defined. Methods and ResultsTo identify genes directly regulated by YAP in cardiomyocytes, we combined differential gene expression analysis in YAP gain- and loss-of-function with genome-wide identification of YAP bound loci using chromatin immunoprecipitation and high throughput sequencing. This screen identified Pik3cb, encoding p110, a catalytic subunit of phosphoinositol-3-kinase (PI3K), as a candidate YAP effector that promotes cardiomyocyte proliferation and survival. We validated YAP and TEAD occupancy of a conserved enhancer within the first intron of Pik3cb, and show that this enhancer drives YAP-dependent reporter gene expression. Yap gain- and loss-of-function studies indicated that YAP is necessary and sufficient to activate the PI3K-Akt pathway. Like Yap, Pik3cb gain-of-function stimulated cardiomyocyte proliferation, and Pik3cb knockdown dampened the YAP mitogenic activity. Reciprocally, Yap loss-of-function impaired heart function and reduced cardiomyocyte proliferation and survival, all of which were significantly rescued by AAV-mediated Pik3cb expression. ConclusionPik3cb is a crucial direct target of YAP, through which the YAP activates PI3K-AKT pathway and regulates cardiomyocyte proliferation and survival.
Pi3kcb links Hippo-YAP and PI3K-AKT signaling pathways to promote cardiomyocyte proliferation and survival.
Specimen part
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