Connexin43 phosphorylation state and intercellular communication in cultured astrocytes following hypoxia and protein phosphatase inhibition

Li, Wei; Nagy, J.I.

doi:10.1046/j.1460-9568.2000.00162.x

Cited by 101 publications

(92 citation statements)

References 39 publications

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“…Consistent with previous findings (Giaume et al, 1991;Li and Nagy, 2000), the astrocytes matured in vitro in this study expressed Cx43. Treatment of the astrocytes with CNTF or CNTFR␣ alone caused no detectable alteration in total Cx43 protein levels compared with vehicle ( Figure 2, A and B).…”

Section: Cntf Complex Increases Cx43 Protein Expression and Intercellsupporting

confidence: 93%

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

Ozog

Bernier

Bates

et al. 2004

MBoC

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Cytokines regulate numerous cell processes, including connexin expression and gap junctional coupling. In this study, we examined the effect of ciliary neurotrophic factor (CNTF) on connexin43 (Cx43) expression and intercellular coupling in astrocytes. Murine cortical astrocytes matured in vitro were treated with CNTF (20 ng/ml), soluble ciliary neurotrophic factor receptor ␣ (CNTFR␣) (200 ng/ml), or CNTF-CNTFR␣. Although CNTF and CNTFR␣ alone had no effect on Cx43 expression, the heterodimer CNTF-CNTFR␣ significantly increased both Cx43 mRNA and protein levels. Cx43 immunostaining correlated with increased intercellular coupling as determined by dye transfer analysis. By using the pharmacological inhibitor ␣-cyano-(3,4-dihydroxy)-N-benzylcinnamide (AG490), the increase in Cx43 was found to be dependent on the Janus tyrosine kinase/signal transducer and activator of transcription (JAK/STAT) pathway. Immunocytochemical analysis revealed that CNTF-CNTFR␣ treatment produced nuclear localization of phosphorylated STAT3, whereas CNTF treatment alone did not. Transient transfection of constructs containing various sequences of the Cx43 promoter tagged to a LacZ reporter into ROS 17/2.8 cells confirmed that the promoter region between ؊838 to ؊1693 was deemed necessary for CNTF-CNTFR␣ to induce heightened expression. CNTF-CNTFR␣ did not alter Cx30 mRNA levels, suggesting selectivity of CNTF-CNTFR␣ for connexin signaling. Together in the presence of soluble receptor, CNTF activates the JAK/STAT pathway leading to enhanced Cx43 expression and intercellular coupling. INTRODUCTIONGap junctions are intercellular channels between adjacent cells that permit the passage of various substances Ͻ1.2 kDa in size (Kumar and Gilula, 1996). Such junctions are formed when each cell provides a connexon, which itself is composed of six connexins (Cxs) (Kumar and Gilula, 1996). Cx43, the prominent Cx isoform expressed in the central nervous system (CNS), is highly expressed in astrocytes (Yamamoto et al., 1990;Dermietzel et al., 1991;Giaume et al., 1991), neuronal precursors (Rozental et al., 1998Bittman and LoTurco, 1999), and possibly neurons (Bruzzone and Ressot, 1997;Vaney, 1999;SiuYi et al., 2001;Rouach et al., 2002). Several studies using in vitro and in vivo models have demonstrated that impediment of gap junctional coupling and/or connexin43 expression amplifies cell death and tissue damage in the wake of injuries and diseases (Blanc et al., 1998;Naus et al., 2001;Siushansian et al., 2001;Ozog et al., 2002b;Lin et al., 2003;Nakase et al., 2003). Thus, design of an intervention to up-regulate Cx43 expression and intercellular communication may lead to novel therapies against pathological disturbances.Gap junction expression and activity can be altered on a short-term or long-term basis (reviewed by Giaume and McCarthy, 1996;Rouach and Giaume, 2001). Short-term regulation is the result of posttranslational processing such as phosphorylation or channel blocking. Long-term regulation, however, entails modification of gene transcripti...

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Section: Cntf Complex Increases Cx43 Protein Expression and Intercellsupporting

confidence: 93%

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

Ozog

Bernier

Bates

et al. 2004

MBoC

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“…This could be due a decreased rate of phosphorylation and/or an increased rate of dephosphorylation of these proteins. It should be noted that hypoxia has been reported to increase activities of the protein phosphatases protein phosphatase 1 (28), calcineurin (34), and tyrosine phosphatase (16) in a number of cell types.…”

Section: Discussionmentioning

confidence: 99%

Permissive Effects of Oxygen on Cyclic AMP and Interleukin-1 Stimulation of Surfactant Protein A Gene Expression Are Mediated by Epigenetic Mechanisms

Islam

Mendelson

2006

Molecular and Cellular Biology

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Surfactant protein A (SP-ATo define mechanisms involved in lung cell-specific, developmental, and hormonal regulation of pulmonary surfactant synthesis, we have focused on surfactant protein A (SP-A), the major surfactant protein, which is lung specific and synthesized in type II cells. SP-A, a member of the collectin subfamily of C-type lectins, plays an important role in immune defense within the lung alveolus by binding to a variety of bacterial, viral, and fungal pathogens to facilitate their uptake by alveolar macrophages and to enhance macrophage migration and cytokine production (see reference 53 for a review). SP-A is an excellent marker of type II cell differentiation and surfactant synthesis in the fetal lung, since it is developmentally regulated with surfactant phospholipid synthesis (see reference 36 for a review). Recently, we obtained compelling evidence that SP-A secreted by the fetal lung into amniotic fluid acts as a hormone that stimulates the migration of amniotic fluid macrophages to the uterus, where they initiate an inflammatory response leading to parturition (13).In studies using midgestation human fetal lung explants cultured in a 20% O 2 environment, we found that type II cell differentiation and SP-A gene expression were enhanced by hormones and factors that increase cyclic AMP (cAMP) (43). Interestingly, cAMP stimulation of type II cell differentiation and SP-A expression are dependent upon a critical atmospheric O 2 tension (1). When fetal lung explants were cultured in a 1 to 2% O 2 -containing environment, type II cells failed to differentiate, and no stimulatory effects of cAMP on SP-A expression were apparent. These findings led us to postulate that increased vascularization of the fetal lung during the third trimester of gestation and enhanced O 2 availability to type II cell precursors may facilitate cAMP induction of type II cell differentiation and surfactant protein gene expression (1).To define genomic regions and response elements involved in lung cell-specific, developmental, and hormonal regulation of SP-A expression, we have utilized transgenic mice and transfected type II cells. In transgenic mice, we found that as little as ϳ400 bp of DNA flanking the 5Ј end of the rabbit SP-A gene directed appropriate lung cell-specific and developmental regulation of expression (3). This region contains four response elements that are individually required for basal and cAMP stimulation of SP-A promoter activity in transfected type II cells (2,17,32,39,56,57). The finding that mutagenesis of any one of these elements markedly reduced basal and cAMP induction of SP-A promoter activity suggests a cooperative interaction of transcription factors binding to these sites. One of these response elements, termed thyroid transcription factor 1 (TTF-1)-binding element (TBE), at Ϫ170 bp binds the homeodomain factor, thyroid transcription factor 1 (TTF-1/Nkx2

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“…Astrocytic Cx43 was described to contribute to the propagation of stress signals from cell to cell after ischemic brain injury, and Cx30 was found to be highly regulated in the hippocampus after hypoxic conditions in young mice, while Cx43 expression remained unchanged (Frantseva et al, 2002;Zeinieh et al, 2010). Additional studies on regulation of gap junction channels under hypoxic conditions revealed dephosphorylation of Cx43 and loss of intercellular coupling in cultured astrocytes (Li and Nagy, 2000). In Cx30/Cx47-deficient mice, the fine regulation of Cx30 channels after hypoxia is not operative, and a potential closure of Cx43 channels between astrocytes under these conditions might result in increased lesion size in Cx30 Ϫ/Ϫ /Cx47 Ϫ/Ϫ mice.…”

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confidence: 96%

Panglial Gap Junctional Communication is Essential for Maintenance of Myelin in the CNS

et al. 2012

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In this study, we have investigated the contribution of oligodendrocytic connexin47 (Cx47) and astrocytic Cx30 to panglial gap junctional networks as well as myelin maintenance and function by deletion of both connexin coding DNAs in mice. Biocytin injections revealed complete disruption of oligodendrocyte-to-astrocyte coupling in the white matter of 10-to 15-d-old Cx30/Cx47 double-deficient mice, while oligodendrocyte-to-oligodendrocyte coupling was maintained. There were no quantitative differences regarding cellular networks in acute brain slices obtained from Cx30/Cx47 double-null mice and control littermates, probably caused by the upregulation of oligodendrocytic Cx32 in Cx30/Cx47 double-deficient mice. We observed early onset myelin pathology, and ϳ40% of Cx30/Cx47 doubledeficient animals died within 42 to 90 d after birth, accompanied by severe motor impairments. Histological and ultrastructural analyses revealed severe vacuolization and myelination defects in all white matter tracts of the CNS. Furthermore, Cx30/Cx47 double-deficient mice exhibited a decreased number of oligodendrocytes, severe astrogliosis, and microglial activation in white matter tracts. Although less affected concerning motor impairment, surviving double-knock-out (KO) mice showed behavioral alterations in the open field and in the rotarod task. Vacuole formation and thinner myelin sheaths were evident also with adult surviving double-KO mice. Since interastrocytic coupling due to Cx43 expression and interoligodendrocytic coupling because of Cx32 expression are still maintained, Cx30/Cx47 double-deficient mice demonstrate the functional role of both connexins for interastrocytic, interoligodendrocytic, and panglial coupling, and show that both connexins are required for maintenance of myelin.

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Connexin43 phosphorylation state and intercellular communication in cultured astrocytes following hypoxia and protein phosphatase inhibition

Cited by 101 publications

References 39 publications

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

The Complex of Ciliary Neurotrophic Factor-Ciliary Neurotrophic Factor Receptor α Up-Regulates Connexin43 and Intercellular Coupling in Astrocytes via the Janus Tyrosine Kinase/Signal Transducer and Activator of Transcription Pathway

Permissive Effects of Oxygen on Cyclic AMP and Interleukin-1 Stimulation of Surfactant Protein A Gene Expression Are Mediated by Epigenetic Mechanisms

Panglial Gap Junctional Communication is Essential for Maintenance of Myelin in the CNS

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