Project description:To characterize mechanisms responsible for the CNS dopamine deficiency and the resulting neuropathology caused by deficiency of the housekeeping purine salvage function hypoxanthine guanine phospho- ribosyltransferase (HPRT) in the Lesch Nyhan Disease (LND), we have used microarray-based methods of global gene expression together with quantitative PCR and Western blot analysis to identify dysregulation of genes and aberrant cellular processes in human fibroblasts and in SH-SY5Y neuroblastoma cells made HPRT-deficient by transduction with a retrovirus stably expressing an shRNA targeted against HPRT. Analysis of the microarray expression data by Gene ontology (GO) and Gene Set Enrichment Analysis (GSEA) as well as by GeneSpring GX10 and Panther Classification System reveal that HPRT deficiency is accompanied by aberrations in a variety of pathways known to regulate neurogenesis or to be implicated in neurodegenerative disease, including the canonical Wnt/β-catenin and the Alzheimer’s disease/presenilin signaling pathways. Dysregulation of the Wnt/β-catenin pathway is confirmed by Western blot demonstration of cytosolic sequestration of β-catenin during in vitro differentiation of the SH-SY5Y cells toward the neuronal phenotype. We also demonstrate that two key transcription factor genes known to be regulated by Wnt signaling and to be vital for the generation and function of dopaminergic neurons; i.e., Lmx1a and Engrailed 1, are down-regulated in the HPRT knockdown SH-SY5Y cells. In addition to the Wnt signaling aberration, we found that expression of presenilin-1 shows a severely disturbed expression in HPRT-deficient cells, reflected by marked instability of the 23kDa C-terminal fragment of presenilin-1 in knockdown cells. Western blot analysis of primary cultures of two LND patients with 2.5% and 0% residual HPRT activity also shows dysregulated b-catenin and presenilin-1 expression, including elevated levels of cytosolic phospho-catenin and, in one of the two patient cells, failure of nuclear transport. Similarly, the presenilin-1 processing defect was most clearly demonstrated by markedly increased levels of both the N-terminal and C-terminal presenilin-1 fragments in the human cell line with no detectable residual enzyme activity but less marked over-expression in the cell with 2.5% residual enzyme activity. These demonstrations of dysregulated Wnt and presenilin-1 signaling and impaired expression of transcription factors necessary for dopaminergic development reveal broad pleitropic neuro-regulatory defects played by HPRT and suggest new directions for investigating mechanisms of aberrant neurogenesis and neuropathology in LND and potential new targets for restoration of effective signaling in this neuro-developmental defect. For microarray analysis, RNAs from triplicate independent cultures of vector-infected HPRT knockdown and control fibroblasts were prepared separately, pooled and used to prepare cRNA and finally subjected to microarray transcriptional analysis in triplicate. The integrity of total RNA from HPRT knockdown and control cells was confirmed by bioanalyzer (Agilent Technologies, Santa Clara, CA). The quality of total RNA samples from HPRT knockdown and control cells was assessed by 2100 bioanalyzer before application to microarray analysis. We determined that the RNA integrity number (RIN), (maximal degradation = 1; maximal molecular integrity = 10) was 10 for both the normal and knockdown cells (data not shown), indicating that isolated RNA samples were of sufficiently high quality to permit subsequent preparation of cDNA for microarray analysis. Microarray transcriptional analysis was performed in triplicate using the HumanWG-6 v3.0 Expression BeadChip system (Illumina, San Diego, CA). All reagents were obtained from HumanWG-6 v.3 Expression BeadChip Kit (Illumina) and all experimental processes were carried out according to manufacturer’s instruction (Illumina). After scanning of hybridized BeadChip, quantitation of slide images were performed using Illumina’s BeadArray software and the raw data were normalized by Loess normalization method, and then the normalized raw data in BeadStudio was exported to GeneSpring GX 10.0.2 (Agilent, Santa Clara, CA). For identification of genes significantly altered in knockdown cell compared with the control normal gene set, total detected entities were filtered by signal intensity value (upper cut-off 100th and lower cut-off 20th percentile) and error (coefficient of variation: CV < 50.0 percent) to remove very low signal entities and to select reproducible signal values of entities among the replicated experiments, respectively. In statistical analysis, t-test unpaired (p < 0.05) was applied and all significant changes above 2-fold were selected. Signals were selected if they were above microarray background (detection p-value < 0.05) in either all six experiments or in at least three knockdown or control experiments. Analysis of GO, GSEA and signaling pathway was carried out using GeneSpring GX 10.0.2 (Agilent) and the PANTHER Classification System (http://www.pantherdb.org/). In the analysis of signaling pathways using GeneSpring GX 10.0.2 (Agilent), a total of 140 cellular pathways were identified. For GSEA analysis, we used the false discovery rate (FDR) of <0.4 and p ≤ 0.1.

Project description:To characterize mechanisms responsible for the CNS dopamine deficiency and the resulting neuropathology caused by deficiency of the housekeeping purine salvage function hypoxanthine guanine phospho- ribosyltransferase (HPRT) in the Lesch Nyhan Disease (LND), we have used microarray-based methods of global gene expression together with quantitative PCR and Western blot analysis to identify dysregulation of genes and aberrant cellular processes in human fibroblasts and in SH-SY5Y neuroblastoma cells made HPRT-deficient by transduction with a retrovirus stably expressing an shRNA targeted against HPRT. Analysis of the microarray expression data by Gene ontology (GO) and Gene Set Enrichment Analysis (GSEA) as well as by GeneSpring GX10 and Panther Classification System reveal that HPRT deficiency is accompanied by aberrations in a variety of pathways known to regulate neurogenesis or to be implicated in neurodegenerative disease, including the canonical Wnt/β-catenin and the Alzheimer’s disease/presenilin signaling pathways. Dysregulation of the Wnt/β-catenin pathway is confirmed by Western blot demonstration of cytosolic sequestration of β-catenin during in vitro differentiation of the SH-SY5Y cells toward the neuronal phenotype. We also demonstrate that two key transcription factor genes known to be regulated by Wnt signaling and to be vital for the generation and function of dopaminergic neurons; i.e., Lmx1a and Engrailed 1, are down-regulated in the HPRT knockdown SH-SY5Y cells. In addition to the Wnt signaling aberration, we found that expression of presenilin-1 shows a severely disturbed expression in HPRT-deficient cells, reflected by marked instability of the 23kDa C-terminal fragment of presenilin-1 in knockdown cells. Western blot analysis of primary cultures of two LND patients with 2.5% and 0% residual HPRT activity also shows dysregulated b-catenin and presenilin-1 expression, including elevated levels of cytosolic phospho-catenin and, in one of the two patient cells, failure of nuclear transport. Similarly, the presenilin-1 processing defect was most clearly demonstrated by markedly increased levels of both the N-terminal and C-terminal presenilin-1 fragments in the human cell line with no detectable residual enzyme activity but less marked over-expression in the cell with 2.5% residual enzyme activity. These demonstrations of dysregulated Wnt and presenilin-1 signaling and impaired expression of transcription factors necessary for dopaminergic development reveal broad pleitropic neuro-regulatory defects played by HPRT and suggest new directions for investigating mechanisms of aberrant neurogenesis and neuropathology in LND and potential new targets for restoration of effective signaling in this neuro-developmental defect.

Project description:GDF8 (myostatin) is a unique cytokine strongly affecting the skeletal muscle phenotype in human and animals. The aim of the present study was to elucidate the molecular mechanism of myostatin influence on the differentiation of mouse C2C12 myoblasts, using the global-transcriptome analysis with the DNA microarray technique. Treatment with exogenous GDF8 strongly affected the growth and development of C2C12 mouse myoblasts. This was manifested by the inhibition of proliferation and differentiation as well as the impairment of cell fusion. DNA microarray analysis revealed 778 genes regulated by GDF8 in differentiating myoblasts (543 down-regulated and 235 up-regulated). Ontological analysis revealed their involvement in 17 types of biological processes, 10 types of molecular functions and 68 different signaling pathways. The effect of GDF8 was mainly mediated by the disruption of the cell cycle, calcium and insulin signaling pathways and expression of cytoskeletal and muscle specific proteins. The identified key-genes that could play a role as GDF8 targets in differentiating myoblasts are: Mef2, Hgf, Ilb1, Itgb1, Edn1, Ppargc1a. After scanning of hybridized microarrays, quantitation of slide images was performed using Feature Extraction Software (Agilent) using default parameters. The raw data were normalized by Loess normalization method, and then the normalized raw data was exported to GeneSpring GX 11.0.5 (Agilent, Santa Clara, CA). For identification of genes significantly altered in cell compared with the control normal gene set, total detected entities were filtered by flags (present, marginal) to remove very low signal entities and to select reproducible signal values of entities among the replicated experiments, respectively. In statistical analysis, separated for experiment with myoblasts treated with GDF8 ([C2C12]-[GDF8]1-4) was used t-test unpaired (p < 0.05) and fold change over 1.6. Analysis of GO and signaling pathway was carried out using GeneSpring GX 12 (Agilent), KEGG and PANTHER Classification System (http://www.pantherdb.org/). In the analysis of signaling pathways using Panther, a total of 68 cellular pathways were identified.

Project description:Background: Follistatin (FS) is an activin-binding glycoprotein, known for its antagonistic action on the TGF-M-NM-2 super-family of cytokines. It has ability to prevent muscle atrophy and to stimulate muscle growth through binding of myostatin (GDF8). FS does not cause these changes only by inhibition of GDF8 but this mechanism is still not well elucidated. In order to identify GDF8-dependent and GDF8-independent action of FS, we performed comprehensive transcriptomic analysis of differentiating C2C12 mouse myoblasts. Results: To evaluate influence of FS-288 (200ng/ml) on differentiating C2C12 myoblasts was used immunofluorescence analysis of MyHC protein expression in the culture and counting of the number and type of myotubes. Differentiating myoblasts treated with FS showed increase in number and size of myotubes. Microarray studies performed by us identified 30 genes oppositely regulated by FS and GDF8. Analyses of the transcriptomic profiles showed that FS has highly significant influence, associated with GDF8 binding, on the regulation of cell cycle, transport processes, cell communication, cell adhesion, cell motion, developmental processes and binding functions. The signalling pathways that may play a primary role in the myogenesis stimulation by FS are associated with TGF-M-NM-2, Delta-Notch and Wnt signalling pathways, integrin and actin cytoskeleton signalling and adipogenesis regulation. Changes in expression of Hgf, Sort1, Trdn, Stmn2, Hdac1 genes, significantly involved in the process of myoblasts differentiation were validated with Real-Time PCR method. Conclusions: Our results implicate which aspects of transcriptional regulation of myogenesis process by FS could have significant and protective influence. We have shown that FS activity is associated not only with GDF8 binding but also with inhibited expression of genes involved in TGF-M-NM-2 signalling and by regulating of genes associated with vesicle transport apoptosis signalling pathway, inflammatory pathways and adipogenesis expression. Our analysis showed that follistatin GDF8-independent on differentiating myotubes involves regulation of localization processes, cell-matrix adhesion, mRNA processing, apoptosis, fatty acid metabolic processes, SNAP receptor activity functions and partial regulation of transcription processes. These results give a new and complete image of the follistatin role in the muscle cell differentiation and indicate target genes for FS which in the future may be a good therapeutic approach. After scanning of hybridized microarrays, quantitation of slide images were performed using Feature Extraction Software 10.7.3.1 (Agilent) using default parameters. Normalized raw data was exported to GeneSpring GX 11.0.5 (Agilent, Santa Clara, CA). For identification of genes significantly altered in cells treated with FSl compared with untreated cells. T total detected entities were filtered by flags (present, marginal) and error (coefficient of variation: CV < 50.0 percent) to remove very low signal entities and to select reproducible signal values of entities among the replicated experiments, respectively. In statistical analysis, separated for experiment with myoblasts treated with FS(FS vs. CTRL 1-4) was used t-test unpaired (p < 0.05) with multiple testing correction: Benjamini-Hochberg <0.05, all significant changes over fold change 1.6 were selected. Analysis of GO, GSEA and signaling pathway was carried out using GeneSpring GX 12 (Agilent) and the DAVID, KEEG and PANTHER Classification System (p<0.01). In the analysis of signaling pathways using GeneSpring GX 12 (Agilent) and Ariadne Pathway Studio.

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UC San Diego_Friedmann_Kang_ESD3_Neuronal Differentiation

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