Project description:Hibernation enables many species of the mammalian kingdom to overcome periods of harsh environmental conditions. During this physically inactive state metabolic rate and body temperature are drastically downregulated, thereby reducing energy requirements (torpor) also over shorter time periods. Since blood cells reflect the organism's current condition, it was suggested that transcriptomic alterations in blood cells mirror the torpor-associated physiological state. Transcriptomics on blood cells of torpid and non-torpid Djungarian hamsters and QIAGEN Ingenuity Pathway Analysis (IPA) revealed key target molecules (TMIPA), which were subjected to a comparative literature analysis on transcriptomic alterations during torpor/hibernation in other mammals. Gene expression similarities were identified in 148 TMIPA during torpor nadir among various organs and phylogenetically different mammalian species. Based on TMIPA, IPA network analyses corresponded with described inhibitions of basic cellular mechanisms and immune system-associated processes in torpid mammals. Moreover, protection against damage of heart, kidney, and liver was deduced from this gene expression pattern in blood cells. This study shows that blood cell transcriptomics can reflect the general physiological state during torpor nadir. Furthermore, the understanding of molecular processes for torpor initiation and organ preservation may have beneficial implications for humans in extremely challenging environments, such as in medical intensive care units and in space.
Project description:Hibernation enables many species of the mammalian kingdom to overcome periods of harsh environmental conditions. During this physically inactive state metabolic rate and body temperature are drastically downregulated, thereby reducing energy requirements (torpor) also over shorter time periods. Since blood cells reflect the organism´s current condition, it was suggested that transcriptomic alterations in blood cells mirror the torpor-associated physiological state. Transcriptomics on blood cells of torpid and non-torpid Djungarian hamsters and QIAGEN Ingenuity Pathway Analysis (IPA) revealed key target molecules (TMIPA), which were subjected to a comparative literature analysis on transcriptomic alterations during torpor/hibernation in other mammals. Gene expression similarities were identified in 148 TMIPA during torpor nadir among various organs and phylogenetically different mammalian species. Based on TMIPA, IPA network analyses corresponded with described inhibitions of basic cellular mechanisms and immune system-associated processes in torpid mammals. Moreover, protection against damage to the heart, kidney, and liver was deduced from this gene expression pattern in blood cells. This study shows that blood cell transcriptomics can reflect the general physiological state during torpor nadir. Furthermore, the understanding of molecular processes for torpor initiation and organ preservation may have beneficial implications for humans in extremely challenging environments, such as in medical intensive care units and in space.
Project description:Comparative transcriptomics of the garden dormouse hypothalamus during early torpor, late torpor and interbout arousal of hibernation
Project description:This study uses advanced proteogenomic approaches in a non-model organism to elucidate cardioprotective mechanisms used during mammalian hibernation. Mammalian hibernation is characterized by dramatic reductions in body temperature, heart rate, metabolism and oxygen consumption. These changes pose significant challenges to the physiology of hibernators, especially for the heart, which maintains function throughout extreme conditions resembling ischemia and reperfusion. To identify novel cardioadaptive strategies we merged large-scale RNA-seq data with large-scale iTRAQ-based proteomic data in heart tissue from thirteen-lined ground squirrels (Ictidomys tridecemlineatus) throughout the circannual cycle. Protein identification and data analysis were run through Galaxy-P, a new multi-omic data analysis platform enabling effective integration of RNA-seq and MS/MS proteomic data. Galaxy-P uses flexible, modular workflows that combine customized sequence database searching and iTRAQ quantification to identify novel ground squirrel-specific protein sequences and provide insight into molecular mechanisms of hibernation. This study allowed for the quantification of 2007 identified cardiac proteins, including over 350 peptide sequences derived from previously uncharacterized protein products. Identification of these peptides allows for improved genomic annotation of this non-model organism, as well as identification of potential splice variants, mutations, or genome re-organization that provide insights into novel cardioprotective mechanisms used during hibernation.
Project description:Mammalian hibernators display phenotypes similar to physiological conditions in non-hibernating species under conditions of calorie restriction and fasting, hypoxia, hypothermia, ischemia-reperfusion, and sleep. However, whether or how similarities are also reflected on molecular and genetic levels is unclear. We identified molecular signatures of torpor and arousal in hibernation using a new custom-designed cDNA microarray for the arctic ground squirrel (Urocitellus parryii,) and compared them to molecular signatures of selected phenotypes in mouse. Our results show that differential gene expression related to metabolism during torpor is closely related to that during calorie restriction and hypoxia. PPARM-NM-1 is crucial for metabolic remodeling in hibernation. Genes related to the sleep-wake cycle and temperature response genes induced by hypothermia follow the same expression changes as in torpor-arousal cycle. Increased fatty acid metabolism might contribute to the protection against ischemia-reperfusion injury during hibernation. Further, by comparing with thousands of pharmacological signatures, we identified drugs that may induce similar expression patterns in human cell lines as during hibernation. Arctic ground squirrels sampled during winter hibernation were compared with the animals sampled during summer. Liver was hybridized on a custom 9,600 probes nylon membrane microarray platform. Four squirrels in early torpor, five in late torpor, four in early arousal, four in late arousal, and seven in summer active were studied in experiments.
Project description:Mammalian hibernators display phenotypes similar to physiological conditions in non-hibernating species under conditions of calorie restriction and fasting, hypoxia, hypothermia, ischemia-reperfusion, and sleep. However, whether or how similarities are also reflected on molecular and genetic levels is unclear. We identified molecular signatures of torpor and arousal in hibernation using a new custom-designed cDNA microarray for the arctic ground squirrel (Urocitellus parryii,) and compared them to molecular signatures of selected phenotypes in mouse. Our results show that differential gene expression related to metabolism during torpor is closely related to that during calorie restriction and hypoxia. PPARα is crucial for metabolic remodeling in hibernation. Genes related to the sleep-wake cycle and temperature response genes induced by hypothermia follow the same expression changes as in torpor-arousal cycle. Increased fatty acid metabolism might contribute to the protection against ischemia-reperfusion injury during hibernation. Further, by comparing with thousands of pharmacological signatures, we identified drugs that may induce similar expression patterns in human cell lines as during hibernation.
Project description:We used single-cell transcriptomics to study >60,000 cells from the developing murine cerebellum, and show that different molecular subgroups of childhood cerebellar tumors mirror the transcription of cells from distinct, temporally restricted cerebellar lineages.
Project description:Thirteen-lined ground squirrels (TLGS) are obligate hibernators that cycle between torpor (low metabolic rate and body temperature) and interbout euthermia (IBE; typical euthermic body temperature and metabolism) from late autumn to spring. Many physiological changes occur throughout hibernation, including a reduction in liver mitochondrial metabolism during torpor, which is reversed during arousal to interbout euthermia. Nuclear-encoded microRNA (small post-transcriptional regulator molecules) differ in abundance throughout TLGS hibernation and have been shown to regulate mitochondrial gene expression in mammalian cell culture (where they are referred to as mitomiRs). This study characterized differences in mitomiR profiles from TLGS liver mitochondria isolated during summer, torpor, and IBE, and predicted their mitochondrial targets. Using small RNA sequencing, differentially abundant mitomiRs were identified between hibernation states and, using qPCR analysis we quantified expression of predicted mitochondrial mRNA targets. Most differences in mitomiR abundances were seasonal (i.e. between summer and winter) with only one mitomiR differentially abundant between IBE and torpor. Multiple factor analysis revealed unique clustering of hibernation states, predominantly driven by mitomiR abundances, and nine of these differentially abundant mitomiRs had predicted mitochondrial RNA targets, including subunits of electron transfer system complexes I and IV, 12S rRNA and two tRNAs. Overall, mitomiRs were predicted to suppress expression of their mitochondrial targets and may have some involvement in regulating protein translation in mitochondria. This study found differences in mitomiR abundances between seasons and hibernation states of TLGS and suggests potential mechanisms in regulating the mitochondrial electron transfer system.
Project description:We report transcriptional changes in grizzly bear muscle during hibernation (February) as compared to before (October). We used Gastrocnemius muscle biopsies taken during Febrary (hibernation) and the October before (activity) for mRNA extraction followed by 454, paired-end and single-end Illumina sequencing. Resulting reads were later mapped to human homologs and used for further analysis.
Project description:The study of the origin and development of cerebellar tumours has been hampered by the complexity and heterogeneity of cerebellar cells that change over the course of development. We used single-cell transcriptomics to study >60,000 cells from the developing murine cerebellum, and show that different molecular subgroups of childhood cerebellar tumours mirror the transcription of cells from distinct, temporally restricted cerebellar lineages. Sonic Hedgehog medulloblastoma transcriptionally mirrors the granule cell hierarchy as expected, whereas Grp3-MB resemble Nestin+ve stem cells, Group 4 medulloblastomas resemble unipolar brush cells, and PFA/PFB ependymoma and cerebellar pilocytic astrocytoma resemble the pre-natal gliogenic progenitor cells. Furthermore, single-cell transcriptomics of human childhood cerebellar tumours demonstrates that many bulk tumours contain a mixed population of cells with divergent differentiation. Our data highlight cerebellar tumours as a disorder of early brain development, and provide a proximate explanation for the peak incidence of cerebellar tumours in early childhood.