Single cell transcriptome analysis of Arabidopsis roots inoculated by Plasmodiophora brassicae indicates a role for brassinosteroids in clubroot formation.
ABSTRACT: The clubroot disease caused by the obligate biotrophic protist Plasmodiophora brassicae on host plants of the Brassicaceae family is characterized by enhanced cell division and cell expansion. Since a typical root section of an infected plant always includes different stages of the pathogen as well as uninfected cells, we were interested to investigate specific developmental stages of the pathogen and their effect on host transcriptional changes. We extended previous microarray studies on whole roots by using Laser Microdissection and Pressure Catapulting (LMPC) to isolate individual cells harboring defined developmental stages of the pathogen. In addition, we compared the central cylinder of infected to contol plants. We were especially interested to elucidate the stage-specific hormonal network. The upregulation of genes involved in auxin and cytokinin metabolism and signaling was confirmed. In addition, we found evidence that brassinosteroid (BR) synthesis and signal perception was in many cases upregulated in enlarged cells and the central cylinder. This was confirmed by qPCR and mutant analysis of the BR receptor mutant bri1-6, which exhibited less severe gall formation than the respective wild type. Our results identify novel hormone pathways involved in clubroot development. Using this method of single cell preparation combined with transcriptome analysis has been very useful to elucidate the regulation of gall growth by this obligate biotropic pathogen in a cell- and stage-specific manner. Transcription profiling was performed in isolated Arabidopsis thaliana root cells harboring different developmental stages of Plasmodiophora brassicae at two time points after inoculation (dai) (14 and 21 dai), as well as in infected central cylinder tissue from roots at 14 dai (days after inoculation). Control samples were taken from uninfected roots. Host cells were dissected from paraffin embedded roots using Laser Microdissection and Pressure Catapulting (LMPC). 8 samples have been analyzed.
Project description:Plasmacytoid dendritic cells (pDCs) are scarcely present in the inflamed human atherosclerotic plaque, where they are presumed to exert pro-inflammatory functions through release of type I interferons. However, the precise role of pDCs in human atherosclerosis yet remains to be established. We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process. We investigated the impact of human plaque pDCs on its local context, applying state of the art transcriptomics analysis on Laser Capture Microdissected fractions of human atherosclerotic plaques, distinctively enriched in pDCs, or pDCs-void.
Project description:Alternative splicing analysis of laser micro-dissected lung dysplasia RNA samples Lung dysplasia is a precancerous condition with high risk of malignant transformation. Little is known about alternative spliced (AS) genes in dysplasia. We therefore investigated laser micro-dissected microscopic foci of non-contaminant dysplasia and/or lung adenocarcinoma of c-Raf transgenic mice and searched genome wide for AS genes using exon arrays. Notably, bioinformatics defined 34 and 36 AS genes in the comparison dysplasia versus transgenic unaltered and non-transgenic lung tissue while the comparison adenocarcinoma versus transgenic unaltered and non-transgenic lung tissue revealed 54 and 56 genes, respectively. So far only 6 of these were reported for lung cancer. Importantly, dysplasia related AS genes were also regulated in lung cancer to suggest a role in disease onset. Next to exon skipping/inclusion alternative splicing at the 3’ and 5’ was common and included genes of the splicing regulatory pathway. Disease dependent changes of variant transcripts were confirmed by RT-PCR while Western blotting identified alternative splicing to modulate protein levels of AS genes. For the AS genes Add3, Cast, Osbpl6, Nedd4l, Numb, Picalm and Slk transcript and protein level agreed well, whereas for Arhgef11, Clstn1, Dlg1, Dock9, Mbnl2, Mfge8, Npnt, Pdlim5, Ppp2r5c, Tjp1 notable differences in the abundance of variant transcripts were observed by RT-PCR and gel electrophoresis. Moreover, expression of individual variants differed between dysplasia and carcinoma to suggest their disease dependent regulation. Western blotting of IQGAP1, MYO6, PTPRM, RABGAP1L and RAD50 confirmed significant regulation of isoforms in lung cancer as compared to non-transgenic, transgenic unaltered and dysplastic lung tissue. For 46 AS genes expression of the non-variant protein was reported in human lung cancer (www.proteinatlas.org) and for 13 of these, cancer related AS events are known. Overall, new insight into lung dysplasia was obtained with 43 new cancer related AS genes to aid diagnosis and molecular intervention strategies. We analyzed and compared dysplastic (n=4) and adenocarcinoma (n=4) lesions and with transgenic but unaltered (n=4) and non-transgenic (n=5) lung tissue obtained from SPC/c-Raf transgenic mice with aid of laser micro dissection pressure catapulted (LMPC) technique. Dysplasia is a pre-neoplastic condition and developed at 5 month of age in the proposed mouse model. LMPC provides precise microscopic lesion collection without contamination. The RNA samples were analyzed using the Affymetrix Mouse Exon 1.0 ST platform. Alternative splicing was analyzed using Biotique XRAY tool. No technical replicates were performed.
Project description:Exploring the expression profile of ovarian clear cell carcinoma cancer cell subpopulations- derived tumors grown within a murine and a human cellular tissues. RNA samples were obtained from laser micro-dissected from two cancer cell subpopulations (CCSPs C12 and C13)- derived tumors that developed within a murine (intratumoral) and a human (intra-teratoma) and from in vitro grown cells; a total of 9 RNA samples of CCSP's C12 and 9 RNA samples of CCSP's C13 .
Project description:The pathogenesis of nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) and its relationship to other lymphomas are largely unknown. This is partly due to the technical challenge of analyzing its rare neoplastic L&H cells, which are dispersed in an abundant non-neoplastic cellular microenvironment. We performed a genome-wide expression study of microdissected lymphocytic and histiocytic (L&H) lymphoma cells in comparison to normal and other malignant B cells, which indicates a relationship of L&H cells to and/or origin from germinal center B cells at transition to memory B cells. L&H cells show a surprisingly high similarity to the tumor cells of T cell-rich B cell lymphoma and classical Hodgkin lymphoma, a partial loss of their B cell phenotype and deregulation of many apoptosis-regulators and putative oncogenes. Importantly, L&H cells are characterized by constitutive NF-κB activity and aberrant ERK signaling. Thus, these findings shed new light on the nature of L&H cells, revealed several novel pathogenetic mechanisms in NLPHL, and may help in differential diagnosis and lead to novel therapeutic strategies. Experiment Overall Design: Analysis of differential gene expression in primary human lymphoma cells of nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) in comparison with primary lymphoma cells of classical Hodgkin lymphoma cells and other B-non-Hodgkin lymphoma (B-NHL) samples and subsets of non-neoplastic B lymphocytes isolated from blood or tonsils. 67 gene expression profiles were analysed.
Project description:Ray cells were enriched from wood samples of poplar (Populus x canescens) by LMPC and transcripts monitored by poplar whole genome microarrays. Results provided insight into molecular processes during the transition from dormancy to flowering in early spring in contrast to the active growth phase in summer. 4 samples of summer (July) 4 of early spring (February) from Populus x canescens field-culture
Project description:The pathogenesis of classical Hodgkin lymphoma (cHL), the most common lymphoma in the young, is still enigmatic, largely because its Hodgkin and Reed-Sternberg (HRS) tumor cells are rare in the involved lymph node and therefore difficult to analyze. Here, by overcoming this technical challenge and performing for the first time a genome-wide transcriptional analysis of microdissected HRS cells in comparison to other B-cell lymphomas, cHL lines and normal B-cell subsets, we show that they differ extensively from the usually studied cHL cell lines, that the lost B-cell identity of cHLs is not linked to the acquisition of a plasma cell-like gene expression program, and that Epstein-Barr virus infection of HRS cells has a minor transcriptional influence on the established cHL clone. Moreover, although cHL appears a distinct lymphoma entity overall, HRS cells of its histological subtypes diverged in their similarity to other related lymphomas. Unexpectedly, we identified two molecular subgroups of cHL associated to differential strengths of the transcription factor activity of the NOTCH1, MYC and IRF4 proto-oncogenes. Finally, HRS cells display deregulated expression of several genes potentially highly relevant to lymphoma pathogenesis, including silencing of the apoptosis-inducer BIK and of INPP5D, an inhibitor of the PI3K-driven oncogenic pathway. The present study complements the GSE12453 and GSE14879 records by adding the following 10 samples: 5 primary tumor samples and 5 cell line samples. The 5 primary tumor samples represent 1000-2000 neoplastic cells microdissected from frozen biopsies of 5 cases of primary mediastinal B-cell lymphoma (PMBL). The 5 cell line samples represent 500-1000 living neoplastic cells isolated by fluorescence-activated cell sorting from growing cultures of the classical Hodgkin lymphoma (cHL) cell lines L1236, L428, KMH2 and HDLM2 and the lymphocyte-predominant Hodgkin lymphoma (lpHL) cell line DEV.
Project description:Tissue of the breast is heterogeneous, consisting of a variety of cell types and connective tissue. This heterogeneity is also present in breast tumors and will complicate proteomic analysis, as it is not always clear whether a signal originates from the stromal environment, from normal epithelial or tumor cells. Here we microdissected a variety of cell types and stroma from benign and malignant breast tissues. We compared proteomic differences between these tissues, both from cells of epithelial origin and the stromal environment. Differences in protein abundances corresponded with several hallmarks of cancer, including loss of cell adhesion, transformation to a migratory phenotype, and enhanced energy metabolism. Furthermore, despite enriching for (tumor) epithelial cells, many changes to the extracellular matrix were detected in microdissected cells of epithelial origin. The stromal compartment was heterogeneous and richer in the number of fibroblast and immune cells in malignant sections, compared to benign tissue sections. Although this heterogeneity complicated detection of differentially abundant proteins, several markers were exclusively detected in stroma. However, as heterogeneity in the stroma is more difficult to be reduced through microdissection, comparative analysis was most informative in microdissected cells of epithelial origin, and provided a relatively complete picture of malignant transformations.
Project description:We used laser capture microdissection to isolate both microvascular endothelial cells and neurons from post mortem brain tissue from patients with schizophrenia and bipolar disorder and healthy controls. RNA was isolated from these cell populations, amplified, and analysed using Affymetrix HG133plus2.0 GeneChips. In the first instance, we used the dataset to compare the neuronal and endothelial data, in order to demonstrate that the predicted differences between cell types could be detected using this methodology. Keywords: cell type comparison, laser capture microdissection The dataset consists of endothelial cell samples from 18 individuals and neuronal samples from an overlapping population of 18 individuals.
Project description:INTRODUCTION. Fixation with formalin, a widely adopted procedure to preserve tissue samples, leads to extensive degradation of nucleic acids and thereby compromises procedures like microarray-based gene expression profiling. We hypothesized that RNA fragmentation is caused by activation of RNAses during the interval between formalin penetration and tissue fixation. To prevent RNAse activation, a series of tissue samples were kept under-vacuum at 4°C until fixation and then fixed at 4°C, for 24 hours, in formalin followed by 4 hours in ethanol 95%. RESULTS. The cold-fixation (CF) procedure preserved DNA and RNA, so that RNA segments up to 660 bp were efficiently amplified. Histological and immunohistochemical features were fully comparable with those of standard fixation. Microarray-based gene expression profiles were comparable with those obtained on matched frozen samples for probes hybridizing within 700 bases from the reverse transcription start site. In conclusion, CF preserves tissues and nucleic acids, enabling reliable gene expression profiling of fixed tissues. Thirty samples from human cancers processed in different ways before RNA extraction: (i) Fresh-Freezing (FF), (ii) Standard Fixation with formalin (SF), (iii) Cold-Fixation (CF), a new formalin fixation procedure preserving nucleic acids. The first six samples compare CF with SF and FF in one colorectal cancer (CRC) specimen and one breast cancer (BRCa) specimen. The subsequent 24 samples compare only CF with FF in various cancer specimens. Expression data are neither normalized nor backound subtracted to preserve the original signal distribution for each sample, which is essential to compare expression profiles obtained after different tissue preservation methods.
Project description:We analysed gene expression in normal breast blood vessels and breast invasive ductal carinoma blood vessels. Normal breast sections and IDC breast sections were immunostained for endothelial-specific CD31. Vessels were dissected and captured with laser capture microscopy, and RNA was extracted and analysed on an Affymetrx array chip. In total, gene expression in blood vessels from 3 normal breast and 3 IDC breast was analysed.