Homeodomain interacting protein kinase 2 (Hipk2) has previously been implicated in control of several transcription factors involved in embryonic development, apoptosis, cell proliferation and tumour development13. Analysis of gene expression in tissues from genetically heterogeneous mouse or human populations can reveal motifs associated with the structural or functional components of the tissue, and may predict roles for genes of unknown function4,5. Here we have applied this network strategy to uncover a novel role for the Hipk2 gene in the transcriptional system controlling adipogenesis. Both in vitro and in vivo models were used to show that knockdown or loss of Hipk2 specifically inhibits white adipose cell differentiation and tissue development. In addition, loss of Hipk2 leads to induction of pockets of multilocular brown fat-like cells in remaining white adipose depots. These cells express markers of brown and beige fat such as uncoupling protein 1 (Ucp1) and transmembrane protein 26 (Tmem26), and thermogenic genes including PPAR- coactivator 1a (Ppargc1a), and cell death-inducing DFFA-like effector a (Cidea). These changes are accompanied by increased insulin sensitivity in Hipk2 knock-out mice and reduced high fat diet-induced weight gain, highlighting a potential role for this kinase in diseases such as diabetes and obesity. Our study underscores the versatility and power of a readily available tissue, such as skin, for network modelling of systemic transcriptional programs involved in multiple pathways, including lipid metabolism and adipogenesis.
Identification of Hipk2 as an essential regulator of white fat development.
Sex, Age, Specimen part
View SamplesIn a randomized controlled dietary intervention study we compared an isocaloric Healthy Nordic diet with the average Nordic diet for influence on abdominal subcutaneous adipose tisse gene expression. We studied obese adults with features of the metabolic syndrom, n=56. There was no significant difference in age, BMI, or gene expression between the groups before the intervention. The intervention lasted for 18-24 weeks.
Healthy Nordic diet downregulates the expression of genes involved in inflammation in subcutaneous adipose tissue in individuals with features of the metabolic syndrome.
Age, Specimen part
View SamplesHypertension is a dominating risk factor for cardiovascular disease. To characterize the genomic response to hypertension, we administered vehicle or angiotensin II to mice and performed gene expression analyses. AngII treatment resulted in a robust increase in blood pressure and altered expression of 235 genes in the aorta, including Gucy1a3 and Gucy1b3 which encode subunits of soluble guanylyl cyclase (sGC). Western blotting and immunohistochemistry confirmed repression of sGC associated with curtailed relaxation via sGC activation. Analysis of transcription factor binding motifs in promoters of differentially expressed genes identified enrichment of motifs for RBPJ, a component of the Notch signaling pathway, and the Notch coactivators FRYL and MAML2 were reduced. Gain and loss of function experiments demonstrated that JAG/NOTCH signaling controls sGC expression together with MAML2 and FRYL. Reduced expression of sGC, correlating with differential expression of MAML2 in stroke prone and spontaneously hypertensive rats was also seen and RNA-Seq data demonstrated correlations between JAG1, NOTCH3, MAML2 and FRYL and the sGC subunits GUCY1A3 and GUCY1B3 in human coronary artery. Notch signaling thus provides a constitutive drive on expression of the major nitric oxide receptor (GUCY1A3/GUCY1B3) in arteries from mice, rats, and humans, and this control mechanism is disturbed in hypertension.
Hypertension reduces soluble guanylyl cyclase expression in the mouse aorta via the Notch signaling pathway.
Specimen part
View SamplesGene expression levels in normal tissues can differ substantially between individuals, due to inherited polymorphisms acting in cis or trans. Analysis of this variation across a population of genetically distinct individuals allows us to visualize a network of co-expressed genes under normal homeostatic conditions, and the consequences of perturbation by tissue damage or disease development. Here, we explore gene expression networks in normal adult skin from 470 genetically unique mice, and demonstrate the dependence of the architecture of signaling pathways on skin tissue location (dorsal or tail skin) and perturbation by induction of inflammation or tumorigenesis. Gene networks related to specific cell types, as well as signaling pathways including Sonic Hedgehog (Shh), Wnt, Lgr family stem cell markers, and keratins differed at these tissue sites, suggesting mechanisms for the differential susceptibility of dorsal and tail skin to development of skin diseases and tumorigenesis. The Pten tumor suppressor gene network is extensively rewired in premalignant tumors compared to normal tissue, but this response to perturbation is lost during malignant progression. We present a software package for eQTL network analysis and demonstrate how network analysis of whole tissues provides insights into interactions between cell compartments and signaling molecules.
Gene Expression Architecture of Mouse Dorsal and Tail Skin Reveals Functional Differences in Inflammation and Cancer.
Sex, Age, Specimen part, Treatment
View SamplesGene expression levels in normal tissues can differ substantially between individuals, due to inherited polymorphisms acting in cis or trans. Analysis of this variation across a population of genetically distinct individuals allows us to visualize a network of co-expressed genes under normal homeostatic conditions, and the consequences of perturbation by tissue damage or disease development. Here, we explore gene expression networks in normal adult skin from 470 genetically unique mice, and demonstrate the dependence of the architecture of signaling pathways on skin tissue location (dorsal or tail skin) and perturbation by induction of inflammation or tumorigenesis. Gene networks related to specific cell types, as well as signaling pathways including Sonic Hedgehog (Shh), Wnt, Lgr family stem cell markers, and keratins differed at these tissue sites, suggesting mechanisms for the differential susceptibility of dorsal and tail skin to development of skin diseases and tumorigenesis. The Pten tumor suppressor gene network is extensively rewired in premalignant tumors compared to normal tissue, but this response to perturbation is lost during malignant progression. We present a software package for eQTL network analysis and demonstrate how network analysis of whole tissues provides insights into interactions between cell compartments and signaling molecules.
Gene Expression Architecture of Mouse Dorsal and Tail Skin Reveals Functional Differences in Inflammation and Cancer.
Sex, Specimen part
View SamplesGene expression levels in normal tissues can differ substantially between individuals, due to inherited polymorphisms acting in cis or trans. Analysis of this variation across a population of genetically distinct individuals allows us to visualize a network of co-expressed genes under normal homeostatic conditions, and the consequences of perturbation by tissue damage or disease development. Here, we explore gene expression networks in normal adult skin from 470 genetically unique mice, and demonstrate the dependence of the architecture of signaling pathways on skin tissue location (dorsal or tail skin) and perturbation by induction of inflammation or tumorigenesis. Gene networks related to specific cell types, as well as signaling pathways including Sonic Hedgehog (Shh), Wnt, Lgr family stem cell markers, and keratins differed at these tissue sites, suggesting mechanisms for the differential susceptibility of dorsal and tail skin to development of skin diseases and tumorigenesis. The Pten tumor suppressor gene network is extensively rewired in premalignant tumors compared to normal tissue, but this response to perturbation is lost during malignant progression. We present a software package for eQTL network analysis and demonstrate how network analysis of whole tissues provides insights into interactions between cell compartments and signaling molecules.
Gene Expression Architecture of Mouse Dorsal and Tail Skin Reveals Functional Differences in Inflammation and Cancer.
Sex
View SamplesHair follicles are self-renewing organs within the skin which cycle through periods of growth and destruction, with an intervening period of outward quiescence. The hair follicle cycle is driven by Hedgehog and Wnt signaling and affects epithelial thickness, melanin production, immune function, and tumor susceptibility. We have previously shown that somatic alterations to the genome affect the genetic architecture of the skin. This study examines how the hair follicle cycle affects gene the genetic architecture in vivo by genomic and genetic analysis of 343 genetically heterogeneous mice during the hair follicle growth phase (anagen) and quiescent phase (telogen). We use eQTL analysis and differential correlation to identify changes in metabolic and stem cell activity not detected by differential expression. Germline influence in gene expression is profoundly higher during anagen, but this increase is not a simple factor of higher levels of gene expression. The most strongly induced eQTLs were involved in cellular energy metabolism and melanogenesis rather than hair follicle growth or hedgehog signaling. We demonstrate that hair follicle and circadian rhythm pathways are sexually dimorphic, but do not find evidence for an effect of sex on eQTL networks. We also use eQTL gene network analysis to identify candidate causal relationships between expression of genes in the hair follicle and melanin pathways, identifying Mcoln3 as a candidate for the familial melanoma locus on 1p22. To lower the bioinformatic barriers to eQTL network analysis we produced CARMEN, a free open-source stand-alone software package. This study demonstrates how to perform a systems genetic analysis of a heterogeneous tissue studied in vivo under physiologically relevant growth signals.
Gene Expression Architecture of Mouse Dorsal and Tail Skin Reveals Functional Differences in Inflammation and Cancer.
Sex, Age, Specimen part
View SamplesGene expression levels in normal tissues can differ substantially between individuals, due to inherited polymorphisms acting in cis or trans. Analysis of this variation across a population of genetically distinct individuals allows us to visualize a network of co-expressed genes under normal homeostatic conditions, and the consequences of perturbation by tissue damage or disease development. Here, we explore gene expression networks in normal adult skin from 470 genetically unique mice, and demonstrate the dependence of the architecture of signaling pathways on skin tissue location (dorsal or tail skin) and perturbation by induction of inflammation or tumorigenesis. Gene networks related to specific cell types, as well as signaling pathways including Sonic Hedgehog (Shh), Wnt, Lgr family stem cell markers, and keratins differed at these tissue sites, suggesting mechanisms for the differential susceptibility of dorsal and tail skin to development of skin diseases and tumorigenesis. The Pten tumor suppressor gene network is extensively rewired in premalignant tumors compared to normal tissue, but this response to perturbation is lost during malignant progression. We present a software package for eQTL network analysis and demonstrate how network analysis of whole tissues provides insights into interactions between cell compartments and signaling molecules.
Gene Expression Architecture of Mouse Dorsal and Tail Skin Reveals Functional Differences in Inflammation and Cancer.
Specimen part, Treatment
View SamplesComplement inhibitor C4b-binding protein (C4BP) is synthesized in liver and pancreas and composed of 7 identical alpha chains and one unique beta chain. We showed previously that C4BP binds islet amyloid polypeptide (IAPP) and affects fibril formation in vitro. Now we found that polymeric C4BP inhibited lysis of human erythrocytes incubated with monomeric IAPP while no erythrocyte lysis was observed after incubation with preformed IAPP fibrils. In contrast, monomeric alpha chain of C4BP had significantly reduced activity. Further, addition of monomeric IAPP to a rat insulinoma cell line (INS-1) resulted in decreased cell viability, which was restored in the presence of physiological concentrations of C4BP. Accordingly, addition of C4BP rescued the ability of INS-1 cells and isolated rat islets to respond to glucose stimulation with insulin secretion, which was impaired in the presence of IAPP alone. C4BP was internalized together with IAPP into INS-1 cells and therefore we aimed to study its effect on gene expression. Pathway analyses of mRNA expression microarray data indicated that cells exposed to C4BP and IAPP in comparison to IAPP alone increased expression of genes involved in cholesterol synthesis. Depletion of cholesterol through methyl--cyclodextrin or cholesterol oxidase abolished the protective effect of C4BP on IAPP cytotoxicity of INS-1 cells. Also, inhibition of phosphoinositide 3-kinase but not NF-B had a similar effect. Taken together, one of the mechanisms by which C4BP protects beta-cells from IAPP cytotoxicity is by enhancing cholesterol synthesis.
C4b-binding Protein Protects β-Cells from Islet Amyloid Polypeptide-induced Cytotoxicity.
Specimen part, Cell line
View SamplesPancreatic islets are central in type 2-diabetes development, which coincides with increased activity of innate immunity. Intriguingly, human pancreatic islets express many complement genes. The most highly expressed gene was the complement inhibitor CD59 that is GPI anchored to the cell membrane, which unexpectedly was found in high amounts intracellularly in beta cells. Silencing of CD59 strongly suppressed insulin secretion. Importantly, this suppression was unrelated to established CD59 functions, but rather depletion of intracellular CD59. Imaging experiments identified a distal site of inhibition in the exocytotic pathway, but prior to emptying of the insulin granules. Proximity Ligation Assays pin-pointed the mechanism to impaired turnover of exocytosis-regulating SNARE-proteins and CD59 was detected in complex with VAMP2 and syntaxin. CD59 was downregulated by 24-h glucose incubations in human islets, rat cell lines and in islets from three rodent diabetes models.
The complement inhibitor CD59 regulates insulin secretion by modulating exocytotic events.
Specimen part
View Samples