Biomedical subjects

Sanda Iacobas

Publications and source records attributed to Sanda Iacobas.

6 recordsLinked to original sources

PubMed2006

Connexin43 and the brain transcriptome of newborn mice.

Our previously reported cDNA array datasets from neonatal wild-type and Cx43-/- (approved gene symbol Gja1) mouse brains were further analyzed to identify underlying interlinkages in the brain transcriptome. The analysis revealed that no gene cohort sharing either primary function or chromosomal location was significantly altered (up-and down-regulation were roughly balanced) in Cx43-/- brains, but each cohort exhibited significant perturbation of transcript abundance proportions and reduced expression variability and coordination. By comparing pairwise expression correlations of all genes with one another in wild-type brains, we found genes exhibiting remarkable similarity or opposition to the coordination profile (set of synergistically, antagonistically, and independently expressed partners) of Cx43, one of the most similar being pannexin1, a vertebrate homolog of invertebrate gap junction proteins. This study indicates striking redundancy of expression controls over functional pathways and suggests that certain genes may play roles similar to or opposite that of Cx43 in organizing the brain transcriptome.

Animals↗

PubMed2006

Transcriptomic changes in developing kidney exposed to chronic hypoxia.

cDNA arrays compared gene expression in kidneys of neonatal mice subjected to 1, 2, and 4 weeks of chronic constant (CCH) or intermittent (CIH) hypoxia with normoxic littermates. Five to twenty percent of genes were regulated in each condition, with greater changes in CCH. Up-regulation of 42% of the solute carriers after 1 week of CCH suggests a strong activation of pH controlling pathways. Significant reduction in expression change of genes important in growth, development, and aging as a function of time indicates reduced maturation rate in CIH and CCH treatments. Regulated genes showed gender dependence in CCH, being higher in females than males at 1 week and higher in males than females thereafter. Transcriptional control was enhanced in CCH but not in CIH. Thus, CCH and CIH both alter gene expression and retard maturation with the more profound changes occurring in CCH than in CIH.

Aging↗

PubMed2005

Connexin43, the major gap junction protein of astrocytes, is down-regulated in inflamed white matter in an animal model of multiple sclerosis.

Both multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), its animal model, involve inflammatory attack on central nervous system (CNS) white matter, leading to demyelination and axonal damage. Changes in astrocytic morphology and function are also prominent features of MS and EAE. Resting astrocytes form a network that is interconnected through gap junctions, composed mainly of connexin43 (Cx43) protein. Although astrocytic gap junctional connectivity is known to be altered in many CNS pathologies, little is known about Cx43 expression in inflammatory demyelinating disease. Therefore, we evaluated the expression of Cx43 in spinal cords of EAE mice compared with healthy controls. Lumbar ventral white matter areas were heavily infiltrated with CD11beta-immunoreactive monocytes, and within these infiltrated regions loss of Cx43 immunoreactivity was evident. These regions also showed axonal dystrophy, demonstrated by the abnormally dephosphorylated heavy-chain neurofilament proteins. Astrocytes in these Cx43-depleted lesions were strongly glial fibrillary acidic protein reactive. Significant loss (38%) of Cx43 protein in EAE mouse at the lumbar portion of spinal cords was confirmed by Western blot analysis. Decreased Cx43 transcript level was also observed on cDNA microarray analysis. In addition to changes in Cx43 expression, numerous other genes were altered, including those encoding adhesion and extracellular matrix proteins. Our data support the notion that, in addition to damage of myelinating glia, altered astrocyte connectivity is a prominent feature of inflammatory demyelination.

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PubMed2004

Sensitivity of the brain transcriptome to connexin ablation.

Extensive studies on mice with total or partial disruption of either connexin43 (Cx43) or connexin32 (Cx32) have detected only subtle changes in central nervous system structure, growth, development, or function. We have used high density cDNA arrays to analyze the regulation, control, and coordination of the abundances of 7446 distinct transcripts in four brains, each of Cx43 null (K43), Cx43 heterozygous (H43), and Cx32 null (K32) mice as compared to the brains of wildtype (W) mice. The use of multiple samples allowed the determination of the statistical significance of gene regulation. Significantly regulated genes encoded proteins of all functional categories, extending beyond those that might be expected to depend on junctional communication. Moreover, we found a high degree of similarity between genes regulated in the K43 and H43 brains and a remarkable overlap between gene regulation in brains of K43 and K32. The regulated genes in both K43 and H43 brains showed an outstanding inverse coordination with the levels of expression of Cx43 in W brain, indicating that the regulated genes are largely predictable from their co-variance with Cx43 in the wildtype samples. These findings lead to the hypothesis that connexin expression may represent a central node in the regulation of gene expression patterns in brain.

Animals↗

PubMed2004

Genes controlling multiple functional pathways are transcriptionally regulated in connexin43 null mouse heart.

We have used mouse 27k cDNA arrays to compare gene expression patterns in four sets of three hearts each of neonatal wild types and four sets of three hearts each of littermates lacking the major cardiac gap junction protein, connexin43 (Cx43). Each individual set of hearts was hybridized against aliquots of an RNA standard prepared from selected mouse tissues, allowing calculation of variability and coordination of gene expression among the samples from both genotypes. Overall variance of gene expression was found to be markedly higher in wild-type hearts than in those from Cx43 null littermates. Expression levels of 586 of 5,613 adequately quantifiable distinct genes with known protein products were statistically altered in the Cx43 null hearts, 38 upregulated and 548 downregulated compared with wild types. Downregulation was confirmed for seven tested genes by quantitative RT-PCR. Functions of proteins encoded by the altered genes encompassed all functional categories, with largest percent changes in genes involved in intracellular transport and transcription factors. Among the downregulated genes in the Cx43 null hearts were those related to neuronal and glial function, suggesting that cardiac innervation might be compromised as a consequence of Cx43 deletion. This was supported by immunodetection of sympathetic innervation, using antibodies to the synaptic vesicle protein synaptophysin and to the adrenergic nerve terminal marker tyrosine hydroxylase. These findings reinforce the proposal that the cardiac abnormality in Cx43 null animals may be contributed by altered innervation and indicate that Cx43 deletion has consequences in addition to reduced intercellular communication.

Animals↗

PubMed2003

Array analysis of gene expression in connexin-43 null astrocytes.

Connexin-43 (Cx43) is the most abundant gap junction protein in brain, where it is found primarily between astrocytes. Although the morphology of astrocytes from Cx43-null (knockout, KO) mice is similar to that of wild-type (WT) astrocytes, KO astrocytes exhibit reduced growth rate in culture. To evaluate the impact of deletion of Cx43 on other genes, including those encoding cell cycle proteins, we used DNA arrays to determine expression patterns in cultured astrocytes from sibling Cx43-null and WT mice. RNA samples extracted from astrocytes cultured from WT and Cx43-null neonatal mice were dye labeled and individually cohybridized with a reference of labeled cDNAs pooled from a variety of tissues on 8 gene arrays containing 8,975 mouse DNA sequences. Normal variability in expression of each gene was evaluated and incorporated into "expression scores" to statistically compare expression levels between WT and KO samples. In Cx43-null astrocytes, 4.1% of the 4,998 adequately quantifiable spots were found to have significantly (P < 0.05) decreased hybridization compared with controls, and 9.4% of the spots showed significantly higher hybridization. The significantly different spots corresponded to RNAs encoding 252 known proteins, many not previously linked to gap junctions, including transcription factors, channels and transporters, cell growth and death signals, enzymes and cell adhesion molecules. These data indicate a surprisingly high degree of impact of deletion of Cx43 on other astrocyte genes, implying that gap junction gene expression alters numerous processes in addition to intercellular communication.

Animals↗