Project description:Direct conversion of fibroblasts to induced cardiomyocytes (iCMs) has great potential for regenerative medicine. Recent publications have reported significant progress, but the evaluation of reprogramming has relied upon non-functional measures such as flow cytometry for cardiomyocyte markers or GFP expression driven by a cardiomyocyte-specific promoter. The issue is one of practicality: the most stringent measures - electrophysiology to detect cell excitation and the presence of spontaneously contracting myocytes - are not readily quantifiable in the large numbers of cells screened in reprogramming experiments. However, excitation and contraction are linked by a third functional characteristic of cardiomyocytes: the rhythmic oscillation of intracellular calcium levels. We set out to optimize direct conversion of fibroblasts to iCMs with a quantifiable calcium reporter to rapidly assess functional transdifferentiation. We constructed a reporter system in which the calcium indicator GCaMP is driven by the cardiomyocyte-specific Troponin T promoter. Using calcium activity as our primary outcome measure, we compared several published combinations of transcription factors along with novel combinations in mouse embryonic fibroblasts. The most effective combination consisted of Hand2, Nkx2.5, Gata4, Mef2c, and Tbx5 (HNGMT). This combination is >50-fold more efficient than GMT alone and produces iCMs with cardiomyocyte marker expression, robust calcium oscillation, and spontaneous beating that persists for weeks following inactivation of reprogramming factors. HNGMT is also significantly more effective than previously published factor combinations for the transdifferentiation of adult mouse cardiac fibroblasts to iCMs. Quantification of calcium function is a convenient and effective means for the identification and evaluation of cardiomyocytes generated by direct reprogramming. Using this stringent outcome measure, we conclude that HNGMT produces iCMs more efficiently than previously published methods. Mouse embryonic fibroblasts were treated with different combinations of transcription factors to drive transdifferentiation to induced cardiomyocytes (iCMs). Putative iCMs were enriched by zeocin selection. Zeocin resistance was conferred to iCMs via the TroponinT-GCaMP5-Zeo lentiviral reporter.

Project description:Somatic transposon mutagenesis in mice is an efficient strategy to investigate the genetic mechanisms of tumorigenesis. The identification of tumor driving transposon insertions traditionally requires the generation of large tumor cohorts to obtain information about common insertion sites. Tumor driving insertions are also characterized by their clonal expansion in tumor tissue, a phenomenon that is facilitated by the slow and evolving transformation process of transposon mutagenesis. We describe here an improved approach for the detection of tumor driving insertions that assesses the clonal expansion of insertions by quantifying the relative proportion of sequence reads obtained in individual tumors. To this end, we have developed a protocol for insertion site sequencing that utilizes acoustic shearing of tumor DNA and Illumina sequencing. We analyzed various solid tumors generated by PiggyBac mutagenesis and for each tumor >10^6 reads corresponding to >10^4 insertion sites were obtained. In each tumor, 9 to 25 insertions stood out by their enriched sequence read frequencies when compared to frequencies obtained from tail DNA controls. These enriched insertions are potential clonally expanded tumor driving insertions, and thus identify candidate cancer genes. The candidate cancer genes of our study comprised many established cancer genes, but also novel candidate genes such as Mastermind-like1 (Mamld1) and Diacylglycerolkinase delta (Dgkd). We show that clonal expansion analysis by high-throughput sequencing is a robust approach for the identification of candidate cancer genes in insertional mutagenesis screens on the level of individual tumors. Solid tumors in mice were generated by somatic transposon mutagenesis with a PiggyBac transposon system. Insertion sites of transposons in 11 tumors and 6 non-cancerous tail controls were determined by Illumina high-throughput sequencing. Insertions were determined both on 5' and 3' sides of the transposon (PB5 and PB3, respectively). Quantitative analysis of read numbers revealed enrichment of certain insertions in tumors, but not in controls, and these enriched insertions identify candidate cancer genes.

Project description:The Infectious Hematopoietic Necrosic Virus (IHNV) DNA vaccine is based on the viral glycoprotein gene (G gene) and induces a non-specific anti-viral immune response and long-term specific immunity against IHNV in salmonid fishes. This study characterized gene expression responses associated with the early anti-viral response. Homozygous rainbow trout were injected intra-muscularly (I.M.) with vector DNA or the IHNV DNA vaccine. Gene expression at the I.M. site was evaluated using a 16,000 feature salmon cDNA microarray. Eighty different transcripts were significantly modulated in the vector DNA group while 910 transcripts were modulated in the IHNV DNA vaccinated group relative to control group. Quantitative reverse transcriptase PCR was used to examine expression of selected genes at the I.M. site and in other secondary tissues. In the localized response (I.M. site), the magnitudes of gene expression changes were higher in the vaccinate group relative to the vector DNA group for the majority of genes analyzed. At secondary systemic sites (e.g. gill, kidney and spleen) evaluated with RT-PCR of specific genes, the main difference was the up-regulation of the type I IFN-related genes in only the IHNV DNA vaccinated group. Keywords: disease vaccine response Gene expression at the site of I.M injection was evaluated 7 days post-injection in clonal rainbow trout. Gene expression was compared across three treatments, with replicate clonal rainbow trout individuals (Hot Creek strain) within each treatment. Treatments included injection with 1X PBS (control group), plasmid vector only (without IHNV G gene; hereafter referred to as vector group), and the pIHNV vaccine (vaccine group). Three clonal individuals from the control, three individuals from the vector group, and four individuals from the vaccine group were labeled with Cy3 and used for individual hybridizations to ten slides, comparing hybridization of each individual to a major reference RNA pool. The major reference pool consisted of three unhandled clonal rainbow trout and constituted a pool of RNA from the anterior kidney, spleen, liver and muscle and was labelled with Cy5. Total RNA was extracted from samples, amplified, and hybridized to 16,000 feature Atlantic salmon cDNA arrays developed by the Genomic Research for Atlantic Salmon project. Differential expression was compared among control, vector, and vaccine groups.

Dataset Information

Direct clonal expansion analyses of cardiomyocytes during development and injury using the Rainbow model

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