The connexin43-dependent transcriptome during brain development: importance of genetic background
ABSTRACT: Use of null mutant mice is a powerful way to evaluate the role of specific proteins in brain function. Studies performed on knockout mice have revealed some unexpected roles of the gap junction proteins (the connexins). Thus, analyses of gene expression in connexin43 (Cx43) null brains indicated that deletion of a single gene (Gja1) induced expression level change of numerous other genes located on all chromosomes and involved in a wide diversity of functional pathways. The significant overlap between alterations in gene expression level, control and coordination in Cx43 knockout and knockdown astrocytes raised the possibility that Gja1 represents a transcriptomic node of gene regulatory networks. However, conditional deletion of Gja1 in astrocytes of two mouse strains resulted in remarkably different phenotypes. In order to evaluate the influence of the genetic background on the transcriptome, we performed microarray studies on brains of GFAP-Cre:Cx43f/f C57Bl/6 and 129/SVEV mice. The surprisingly low number of Cx43 core genes (regulated in all Cx43 nulls regardless of strain) and the high number of differently regulated genes in the two Cx43 CKOs indicate high influence of mouse strain on brain transcriptome. The transcriptomes of WT and Cx43 null brains from both C57Bl/6 and SVEV strains were profiled and compared at perinatal and adult time points to learn more about the strain dependence of the Cx43-null phenotype. For this purpose, differently labeled cDNAs from biological replicas (4 of each genotype) were co-hybridized with Duke MO36K mouse oligonucleotide array spotted with 36k Operon oligonucleotides V4.0.
Project description:Although bone marrow-derived mononuclear cells (BMNC) have been extensively used in cell therapy for cardiac diseases, little mechanistic information is available to support reports of their efficacy. To address this shortcoming, we compared structural and functional recovery and associated global gene expression profiles in post-ischaemic myocardium treated with BMNC transplantation. BMNC suspensions were injected into cardiac scar tissue 10 days after experimental myocardial infarction. Six weeks later, mice undergoing BMNC therapy were found to have normalized antibody repertoire and improved cardiac performance measured by ECG, treadmill exercise time and echocardiography. After functional testing, gene expression profiles in cardiac tissue were evaluated using high-density oligonucleotide arrays. Expression of more than 18% of the 11981 quantified unigenes was significantly altered in the infarcted hearts. BMNC therapy restored expression of 2099 (96.2%) of the genes that were altered by infarction but led to altered expression of 286 other genes, considered to be a side effect of the treatment. Transcriptional therapeutic efficacy, a metric calculated using a formula that incorporates both recovery and side effect of treatment, was 73%. In conclusion, our results confirm a beneficial role for bone marrow-derived cell therapy and provide new information on molecular mechanisms operating after BMNC transplantation on post ischemic heart failure in mice. We compared RNA samples extracted from whole hearts of infarcted mouse myocardium treated with bone marrow mononuclear cells control with untreated infarcted and control mice samples by analyzing hybridization to AECOM 32k mouse microarrays (http://microarray1k.aecom.yu.edu/) spotted with Operon version 3.0 70-mer oligonucleotides. The hybridization protocol and the slide type were uniform throughout the entire experiment to minimize the technical noise. Treated, control (sham) and infarcted red-labeled heart samples were hybridized against an in-house prepared green-labeled universal mouse reference.
Project description:After myocardial infarction (MI) activation of the immune system and inflammatory mechanisms, among others, can lead to ventricular remodeling and heart failure (HF). Interaction between these systemic alterations and corresponding changes in the heart has not been extensively examined in the setting of chronic ischemia. The main purpose of this study was to investigate alterations in cardiac gene and systemic cytokine profile in mice with post-ischemic HF. Plasma was tested for IgM and IgG anti-heart reactive repertoire and inflammatory cytokines. Heart samples were assayed for gene expression. Ischemic HF significantly increased the levels of serum IgM (by 5.2 fold) and IgG (by 3.6 fold) associated with remarkable content of anti-heart specificity. Comparable increase was observed in levels of circulating pro-inflammatory cytokines, such as IL-1β (3.8x) and TNF-α (6.0x). IFN-gamma was also increased in the MI group by 3.1x. However, IL-4 and IL-10 showed no significant difference between MI and sham groups. Chemokines such as MCP-1 and IL-8 were enhanced in the plasma of infarcted mice. We identified 2079 well annotated unigenes that were significantly regulated by the post-ischemic HF. Complement activation and immune response was among the most up-regulated processes. Interestingly, 21 out of the 101 quantified unigenes involved in inflammatory response were significantly up-regulated and none were down-regulated. These data indicate that post-ischemic heart remodeling is accompanied by immune mediated mechanisms that act both systemically and locally. We compared RNA samples extracted from whole hearts of control and infarcted mice samples by analyzing hybridization to AECOM 32k mouse microarrays (http://microarray1k.aecom.yu.edu/) spotted with Operon version 3.0 70-mer oligonucleotides. The hybridization protocol, the slide type and the scanner settings were uniform throughout the entire experiment to minimize the technical noise. Control (sham) and infarcted red-labeled heart samples were hybridized against an in-house prepared green-labeled universal mouse reference.
Project description:Injury of the CA1 subregion induced by a single injection of kainic acid (1×KA) is attenuated when juvenile animals (P20) have a history of two sustained neonatal seizures on P6 and P9. To identify gene candidates involved in the spatially protective effects produced by early life conditioning seizures, we profiled and compared the transcriptomes of CA1 subregions from control, 1×KA, and 3×KA treated animals. More genes were regulated following 3×KA (9.6%) than after 1×KA (7.1%). Following 1×KA, genes supporting oxidative stress, growth, development, inflammation, and neurotransmission were upregulated (e.g., Cacng1, Nadsyn1, Kcng1, Aven, S100a4, GFAP, Vim, Hrsp12, Grik1). After 3×KA, protective genes were differentially over-expressed (e.g., Cat, Gpx7, GAD1, Hspa12A, Foxn1, adenosine A1 receptor, Ca2+ adaptor and homeostatic proteins, Cacnb4, Atp2b2, anti-apoptotic Bcl-2 gene members, intracellular trafficking protein, Grasp, suppressor of cytokine signaling (Socs3)). Distinct anti-inflammatory interleukins not observed in adult tissues (e.g., IL6 transducer, IL23 and IL33 or their receptors (ILF2)) were also over-expressed. Several transcripts were validated by real-time polymerase chain reaction (QPCR) and immunohistochemistry. QPCR showed that casp 6 was increased after 1×KA but reduced after 3×KA; pro-inflammatory gene cox1 was either upregulated or unchanged after 1×KA but reduced by ~70% after 3×KA. Enhanced GFAP immunostaining following 1×KA was selectively attenuated in the CA1 subregion after 3×KA. The observed differential transcriptional responses may contribute to early life seizure-induced pre-conditioning and neuroprotection by reducing glutamate receptor-mediated Ca2+ permeability of the hippocampus and redirecting inflammatory and apoptotic pathways which could lead to new genetic therapies for epilepsy. The transcriptomes of the hippocampal CA1 region of Sprague Dawley 23-day-old male rats after 1 or 3 seizures induced by kainic acid injection were compared to the corresponding controls (injected with PBS) using Duke 27k oligonucleotide arrays.
Project description:Expression level, control and intercoordination of 66 selected heart rhythm determinant (HRD) genes were compared in atria and ventricles of 4 male and 4 female adult mice. We found that genes encoding various adrenergic receptors, ankyrins, ion channels and transporters, connexins and other components of the intercalated discs form a complex network that is chamber dependent and differs between the two sexes. In addition, most HRD genes in atria had higher expression in males than in females, while in ventricles expression levels were mostly higher in females than in males. Moreover, significant chamber-differences were observed between the sexes, with higher expression in atria than ventricles for males and higher expression in ventricles than atria for females. We have ranked the selected genes according to their prominence in controlling the HRD gene web through expression coordination with the other web genes and protecting the web though their own expression stability. Interestingly, the prominence hierarchy was substantially different between the two sexes. Taken together these findings indicate that the organizational principles of the heart rhythm transcriptome are sex-dependent, with the newly introduced prominence analysis allowing identification of genes that are pivotal for the sexual dichotomy. Four adult male (M) and 4 adult female (F) mice were decapitated, the hearts removed and atria (A) and ventricles (V) collected in separate tubes. 20 µg total RNA extracted in Trizol from each of the 16 samples was reverse transcribed in the presence of fluorescent Alexa Fluor®_647 and Alexa Fluor®_555-aha-dUTPs (Invitrogen, CA) to obtain labeled cDNAs Red and green-labeled samples of biological replicas were then co-hybridized (“multiple yellow” strategy) overnight at 50°C with mouse MO36k oligonucleotide arrays printed by Duke University (http://microarray.genome.duke.edu/spotted-arrays) with Operon Mouse Oligo Set, version 4.0. After washing (0.1% SDS and 1% SSC) to remove the non-hybridized cDNA, each array was scanned with GenePix 4000B scanner (MDS, Toronto, Canada) and images were primarily analyzed with GenePixPro 6.0 (Axon Instruments, CA).
Project description:We examined the extent to which different Trypanosoma cruzi strains induce transcriptomic changes in cultured L6E9 myoblasts 72 hours or 48 hours after infection with four strains of the parasite [Brazil (TCI); Y, CL and Tulahuen (TC II) strains]. Expression of 6,289 distinct fully annotated unigenes was quantified with 27k rat oligonucleotide arrays in each of the four replicas of all control and infected RNA samples. Considering changes >1.5-fold and p-val<0.05, the Tulahuen strain was the most disruptive to host transcriptome, with (17% significantly altered genes), while in Y strain altered only 6% of the genes were altered. The significantly altered genes in the infected cells were largely different among the four strains, with only 21 genes changed in the same direction being similarly changed by all four strains. However, when expression ratios of all genes were compared, myoblasts infected with different strains showed proportional overall genbe expression alterations. These results indicate that infection with different parasite strains modulates similar but not identical pathways in the host cells. 20 µg total RNA extracted in Trizol from each of the 20 cell culture dishes containing control or infected with (Y, CL, Tulahuen or Brazil) Trypanosoma cruzi strains (4 dishes for each strain) was reverse transcribed in the presence of fluorescent Alexa Fluor®_647 or Alexa Fluor®_555-aha-dUTPs (Invitrogen, CA) to obtain labeled cDNAs. Red and green-labeled samples of biological replicas were then co-hybridized (“multiple yellow” strategy) overnight at 50°C with Operon v3.0 Rat 27k oligonucleotide arrays printed by Duke University (GPL9207). After washing (0.1% SDS and 1% SSC) to remove the non-hybridized cDNA, each array was scanned with GenePix 4000B scanner (MDS, Toronto, Canada) and images were primarily analyzed with GenePixPro 6.0 (Axon Instruments, CA).
Project description:One way by which astrocytes modulate oligodendrocytes’ activity is by delivering neurotransmitters and leukemia inhibitory factor (Lif) in the medium that bind oligodendrocyte receptors. Most of these receptors are involved in intercellular Ca2+-signaling (ICS). However, not much is known about the interactions between myelination (MYE) and ICS genes and how astrocyte nearness modulates the oligodendrocyte genomic myelination fabric. We profiled the transcriptomes of immortalized oligodendrocyte precursor cells (Oli-neu) when cultured alone or co-cultured with cortical astrocytes. The astrocytes were plated in cell culture insert systems that did not allow formation of gap junction channels with oligodendrocytes but permitted exchange of soluble factors via the culture medium. Remarkably, astrocyte proximity induced a larger increase of the overall expression level and interlinkage of MYE genes than the differentiating 10d treatment with 1 mM dibutyryl cAMP that turns Oli-neu cells into myelin-associated glycoprotein-positive oligodendrocyte-like cells. Moreover, more MYE and ICS genes were turned on and fewer turned off by astrocyte proximity than by differentiating treatment. Lif receptor was up-regulated by astrocyte proximity but not by the differentiating treatment. We have identified the responsible transcriptomic networks by which the intercellular ICS gene web controls MYE gene web, with genes encoding the gap junction proteins (connexins, Cx) Cx29, Cx32 and Cx47 playing central roles. The novel Prominent Gene Analysis (that refines iteratively the functional webs to optimize the interconnectivity and expression stability of the associated genes) was used to select and rank the most relevant MYE and ICS genes and build the corresponding gene webs. Determine the modifications of the myelination transcriptome induced in Oli- neu control cells by differentiating treatment and proximity of cortical astrocytes. Four culture dishes of each of control, differentiated and in the astrocyte proximity Oli-neu cells were profiled using Duke mouse 30K and 36k oligonucleotide arrays in the "multiple yellow" hybrization design.
Project description:Chronic chagasic cardiomyopathy is a leading cause of heart failure in Latin American countries. About 30% of Trypanosoma cruzi-infected individuals develop this severe symptomatic form of the disease, characterized by intense inflammatory response accompanied by fibrosis deposition in the heart. We performed a microarray analysis of a mouse model of this disease and identified >5% alterations of gene expression in the heart. Most of the upregulations were associated with immune-inflammatory responses (chemokines, adhesion molecules, cathepsins and MHC molecules) and fibrosis deposition (extracellular matrix components, lysyl oxidase and Timp1). Our results indicate potentially relevant factors involved in the pathogenesis of the disease that may provide new therapeutic targets in chronic Chagas’ disease. The heart transcriptomes of 4 age-mached Trypanosoma cruzi-infected and 4 control C57Bl/6 mice were profiled and compared using Duke Mouse 30k Oligonucleotide Arrays (Operon V3.0.1) hybridized in the "multiple yellow" strategy described in Iacobas et al, Biochem Biophys Res Commun. 2006 349(1):329-38.
Project description:Chronic chagasic cardiomyopathy is one of the leading causes of heart failure in Latin American countries, being associated with intense inflammatory response and fibrosis. We have previously shown that bone marrow mononuclear cell (BMC) transplantation improves inflammation, fibrosis and ventricular diameter in hearts of mice with chronic Chagas’ disease. Here we investigated alterations of gene expression in the hearts of chronic chagasic mice submitted or not to BMC therapy. C57Bl/6 mice chronically infected with T. cruzi (6 months) were transplanted with BMC or saline i.v. and sacrificed 2 months later. RNA was extracted from the hearts of normal controls, chagasic and BMC transplanted mice and microarray analysis was performed using MO30k oligonucleotide arrays. Out of the 9390 unigenes quantified in all samples, 1702 had their expression altered in chronic chagasic hearts compared to those of normal mice. Major categories of significantly upregulated genes were related to inflammation, fibrosis and immune responses, while genes involved in mitochondrion function were downregulated. When BMC-treated chagasic hearts were compared to infected mice, 1631 (96%) of the alterations detected in infected hearts were not found, although an additional 109 genes were altered by treatment, indicating a remarkable 84% transcriptomic recovery. Immunofluorescence and morphometric analyses confirmed the effects of BMC therapy in the pattern of inflammatory-immune response and expression of adhesion molecules. Our results demonstrate important immunomodulatory effects of BMC therapy in chagasic cardiomyopathy and indicate potentially relevant factors involved in the pathogenesis of the disease that may provide new therapeutic targets. We compared RNA samples extracted from whole hearts of 4 control, 4 chagasic and 4 BMC-treated chagasic mice by analyzing hybridization to microarrays printed by Duke University (http://www.ncbi.nlm.nih.gove/geo/query/acc.cgi?acc=GPL8938) spotted with MO30k mouse Operon version 3.0 70-mer oligonucleotides. The hybridization protocol (see Soares et al, 2010), the slide type and the scanner settings were uniform throughout the entire experiment to minimize the technical noise. Briefly, 20 ug total RNA extracted in Trizol from each of the twelve samples (individual hearts) was reverse transcribed in the presence of fluorescent Alexa Fluor® 555- and Alexa Fluor®647-aha-dUTPs (Invitrogen, Carlsbad, CA) to obtain labeled cDNA. Red and green labeled samples of biological replicas were then co-hybridized (“multiple yellow” strategy, 22) overnight at 50° C. After washing (0.1% SDS and 1% SSC) to remove the non-hybridized cDNA, each array was scanned at 630V (635 nm) and 580V (532 nm) with GenePix 4100B scanner (Axon Instruments, Union City, CA) and images were primarily analyzed with GenePixPro 6.0 (Molecular Devices, Sunnyvale, CA). Microarray data were processed as described previously (Soares et al, 2010). A gene was considered as significantly up- or down-regulated when comparing four hearts from one condition to those from another if the absolute fold change was >1.5x and the p-vlaue of the Sutdent”s heteroscedastic t-test of equality of the means of the distributions with a Bonferroni-type adjustment for each redundancy group (set of spots probing the same gene) was <0.05.
Project description:Trypanosoma cruzi infection is a major cause of cardiomyopathy. Gene profiling studies of hearts from infected mice have revealed prominent changes in gene expression within many functional pathways. This variety of transcriptomic changes in infected mice raises the question of whether gene expression alterations in whole hearts are due to changes in infected cardiac myocytes or other cells or even to systemic effects of the infection on the heart. We employed microarrays to examine infected cardiac myocyte cultures 48 hr post-infection. Statistical comparison of gene expression levels of 2,258 well annotated unigenes in four independent cultures of infected and uninfected myocytes detected (p < 0.05) significant > 1.5 absolute fold changes in 221 (8.8%) of the sampled genes. Major categories of affected genes included those involved in immune response, extracellular matrix and cell adhesion. While changes in extracellular matrix and cell adhesion genes were anticipated, modulation of immune response genes in the infected myocytes was surprising. These findings on infected cardiac myocytes in culture reveal that altered gene expression described in the heart in Chagas disease are the consequence of both direct infection of the myocytes and resulting from presence of other cell types in the myocardium and systemic effects of infection. Transcriptomic alteration in neonatal mouse cultured cardiomyocytes induced by the parasite T.cruzi were detected by profiling and compared using AECOM mouse 32k oligonucleotide arrays hybridized in the "multiple yellow" strategy described in Iacobas et al, Biochem Biophys Res Commun. 2006 349(1):329-38.
Project description:RATIONALE:Delivery of Cx43 (connexin 43) to the intercalated disc is a continuous and rapid process critical for intercellular coupling. By a pathway of targeted delivery involving microtubule highways, vesicles of Cx43 hemichannels are efficiently trafficked to adherens junctions at intercalated discs. It has also been identified that actin provides rest stops for Cx43 forward trafficking and that Cx43 has a 20 kDa internally translated small C terminus isoform, GJA1-20k (Gap Junction Protein Alpha 1- 20 kDa), which is required for full-length Cx43 trafficking, but by an unknown mechanism. OBJECTIVE:We explored the mechanism by which the GJA1-20k isoform is required for full-length Cx43 forward trafficking to intercalated discs. METHODS AND RESULTS:Using an in vivo Adeno-associated virus serotype 9-mediated gene transfer system, we confirmed in whole animal that GJA1-20k markedly increases endogenous myocardial Cx43 gap junction plaque size at the intercalated discs. In micropatterned cell pairing systems, we found that exogenous GJA1-20k expression stabilizes filamentous actin without affecting actin protein expression and that GJA1-20k complexes with both actin and tubulin. We also found that filamentous actin regulates microtubule organization as inhibition of actin polymerization with a low dose of latrunculin A disrupts the targeting of microtubules to cell-cell junctions. GJA1-20k protects actin filament from latrunculin A disruption, preserving microtubule trajectory to the cell-cell border. For therapeutic implications, we found that prior in vivo Adeno-associated virus serotype 9-mediated gene delivery of GJA1-20k to the heart protects Cx43 localization to the intercalated discs against acute ischemic injury. CONCLUSIONS:The internally translated GJA1-20k isoform stabilizes actin filaments, which guides growth trajectories of the Cx43 microtubule trafficking machinery, increasing delivery of Cx43 hemichannels to cardiac intercalated discs. Exogenous GJA1-20k helps to maintain cell-cell coupling in instances of anticipated myocardial ischemia.