Primary Structure, Organization, and Expression of the Rat Connexin45 Gene

Teunissen, Birgit E.J.; Jansen, Anita; Mutsaers, Nancy; Vuerhard, Maria J.; Vos, Marc A.; Bierhuizen, Marti F.A.

doi:10.1089/dna.2006.0540

Cited by 5 publications

(3 citation statements)

References 31 publications

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“…Total RNA was isolated from WT and MHC-CnA ventricles (n = 4) with TRIzol reagent (Invitrogen by Life Technologies Corp.) and subsequently treated with DNAse I (Promega, Madison, WI, USA) as previously described [18]. One µg of RNA was converted to cDNA with Reverse Transcriptase (Invitrogen by Life Technologies Corp.) according to the manufacturer’s protocol and diluted 10-fold prior to PCR amplification.…”

Section: Methodsmentioning

confidence: 99%

Changes in Cx43 and NaV1.5 Expression Precede the Occurrence of Substantial Fibrosis in Calcineurin-Induced Murine Cardiac Hypertrophy

et al. 2014

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In mice, the calcium-dependent phosphatase calcineurin A (CnA) induces a transcriptional pathway leading to pathological cardiac hypertrophy. Interestingly, induction of CnA has been frequently noticed in human hypertrophic and failing hearts. Independently, the arrhythmia vulnerability of such hearts has been regularly associated with remodeling of parameters determining electrical conduction (expression level of connexin43 (Cx43) and NaV1.5, connective tissue architecture), for which the precise molecular basis and sequence of events is still unknown. Recently, we observed reduced Cx43 and NaV1.5 expression in 4-week old mouse hearts, overexpressing a constitutively active form of CnA (MHC-CnA model), but the order of events is still unknown. Therefore, three key parameters of conduction (Cx43, NaV1.5 and connective tissue expression) were characterized in MHC-CnA ventricles versus wild-type (WT) during postnatal development on a weekly basis. At postnatal week 1, CnA overexpression induced cardiac hypertrophy in MHC-CnA. Moreover, protein and RNA levels of both Cx43 and NaV1.5 were reduced by at least 50% as compared to WT. Cx43 immunoreactive signal was reduced at week 2 in MHC-CnA. At postnatal week 3, Cx43 was less phosphorylated and RNA level of Cx43 normalized to WT values, although the protein level was still reduced. Additionally, MHC-CnA hearts displayed substantial fibrosis relative to WT, which was accompanied by increased RNA levels for genes previously associated with fibrosis such as Col1a1, Col1a2, Col3a1, Tgfb1, Ctgf, Timp1 and microRNA miR-21. In MHC-CnA, reduction in Cx43 and NaV1.5 expression thus coincided with overexpression of CnA and hypertrophy development and preceded significant presence of fibrosis. At postnatal week 4 the alterations in conductional parameters observed in the MHC-CnA model lead to abnormal conduction and arrhythmias, similar to those observed in cardiac remodeling in heart failure patients. The MHC-CnA model, therefore, provides for a unique model to resolve the molecular origin of conductional remodeling in detail.

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Section: Methodsmentioning

confidence: 99%

Changes in Cx43 and NaV1.5 Expression Precede the Occurrence of Substantial Fibrosis in Calcineurin-Induced Murine Cardiac Hypertrophy

et al. 2014

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“…26 After cDNA synthesis, expression of mouse collagen type 1␣2 (COL1A2) was assessed by quantitative real-time polymerase chain reaction using TaqMan Gene Expression Assays with predesigned probe and primers (Applied Biosystems). The GAPDH was used as an internal reference.…”

Section: Quantitative Polymerase Chain Reactionmentioning

confidence: 99%

Reduced Cx43 Expression Triggers Increased Fibrosis Due to Enhanced Fibroblast Activity

Jansen

Veen

Jong

et al. 2012

Circ: Arrhythmia and Electrophysiology

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Background-Arrhythmogenic ventricular remodeling is hallmarked by both reduced gap junction expression and increased collagen deposition. We hypothesized that reduced connexin43 (Cx43) expression is responsible for enhanced fibrosis in the remodeled heart, resulting in an arrhythmogenic substrate. Therefore, we investigated the effect of normal or reduced Cx43 expression on the formation of fibrosis in a physiological (aging) and pathophysiological (transverse aortic constriction [TAC]) mouse model. Methods and Results-The Cx43fl/fl and Cx43 CreER(T)/fl mice were aged 18 to 21 months or, at the age of 3 months, either TAC or sham operated and euthanized after 16 weeks. Epicardial activation mapping of the right and left ventricles was performed on Langendorff perfused hearts. Sustained ventricular arrhythmias were induced in 0 of 11 aged Cx43 fl/fl and 10 of 15 Cx43Cre-ER(T)/fl mice (PϽ0.01). Cx43 expression was reduced by half in aged Cx43 CreER(T)/fl compared with aged Cx43 fl/fl mice, whereas collagen deposition was significantly increased from 1.1Ϯ0.2% to 7.4Ϯ1.3%. Aged Cx43CreER(T)/fl mice with arrhythmias had significantly higher levels of fibrosis and conduction heterogeneity than aged Cx43CreER(T)/fl mice without arrhythmias. The TAC operation significantly increased fibrosis in control compared with sham (4.0Ϯ1.2% versus 0.4Ϯ0.06%), but this increase was significantly higher in Cx43CreER(T)/fl mice (10.8Ϯ1.4%). Discoidin domain receptor 2 expression was unchanged, but procollagen peptide I and III expression and collagen type 1␣2 mRNA levels were higher in TAC-operated Cx43HZ mice. Conclusions-Reduced cellular coupling results in more excessive collagen deposition during aging or pressure overload in mice due to enhanced fibroblast activity, leading to increased conduction in homogeneity and proarrhythmia. (Circ Arrhythm Electrophysiol. 2012;5:380-390.)Key Words: arrhythmia Ⅲ collagen Ⅲ electrophysiology mapping Ⅲ connexin43 Ⅲ fibroblast I n the heart, the highly orchestrated propagation of the electric impulse balances on the delicate interplay between excitability, cell-to-cell coupling, and architecture of myocardial tissue. An important aspect of the myocardial architecture is interstitial collagen (fibrosis), which, together with connexin43 (Cx43), determines cell-to-cell coupling in ventricular myocardium. Under normal physiological conditions, the amount of collagen between the cardiomyocytes is low (Ͻ1% of total tissue volume) but contributes to the structural organization of the heart and the anisotropic character of impulse propagation. We recently showed that, in senescent mouse hearts, collagen content was increased (200%) and Cx43 expression was decreased (50%), changes that were associated with increased inducibility of ventricular tachycardias. 1 On the other hand, when the excessive deposition of fibrosis was prevented through long-term inhibition of the renin-angiotensin-aldosterone system, the normal pattern of Cx43 expression was preserved and arrhythmia vulnerability was strongly red...

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“…Most mammalian Cx genes consist of two exons, with exon 1 encoding the 5′-untranslated region (5′-UTR), while exon two contains the complete coding sequence (CDS) and the 3′-UTR. However, GJB1 and GJC1 (encoding Cx32 and Cx45, respectively) have more than two exons, with exon 3 encoding the CDS (Teunissen et al, 2007). Hydropathy plots of Cxs predict a common membrane topology consisting of four hydrophobic membrane-spanning domains (M1–M4), connected by two extracellular loops (El and E2) and one intracellular loop, with C- and N-termini both in the cytoplasm.…”

Section: Molecular Structure and Pattern Of Expression Of Cochlear Gjsmentioning

confidence: 99%

Structure and Function of Cochlear Gap Junctions and Implications for the Translation of Cochlear Gene Therapies

Zhang

Li³

et al. 2019

Front. Cell. Neurosci.

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Connexins (Cxs) are ubiquitous membrane proteins that are found throughout vertebrate organs, acting as building blocks of the gap junctions (GJs) known to play vital roles in the normal function of many organs. Mutations in Cx genes (particularly GJB2, which encodes Cx26) cause approximately half of all cases of congenital hearing loss in newborns. Great progress has been made in understanding GJ function and the molecular mechanisms for the role of Cxs in the cochlea. Data reveal that multiple types of Cxs work together to ensure normal development and function of the cochlea. These findings include many aspects not proposed in the classic K+ recycling theory, such as the formation of normal cochlear morphology (e.g., the opening of the tunnel of Corti), the fine-tuning of the innervation of nerve fibers to the hair cells (HCs), the maturation of the ribbon synapses, and the initiation of the endocochlear potential (EP). New data, especially those collected from targeted modification of major Cx genes in the mouse cochlea, have demonstrated that Cx26 plays an essential role in the postnatal maturation of the cochlea. Studies also show that Cx26 and Cx30 assume very different roles in the EP generation, given that only Cx26 is required for normal hearing. This article will review our current understanding of the molecular structure, cellular distribution, and major functions of cochlear GJs. Potential implications of the knowledge of cochlear GJs on the design and implementation of translational studies of cochlear gene therapies for Cx mutations are also discussed.

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Primary Structure, Organization, and Expression of the Rat Connexin45 Gene

Cited by 5 publications

References 31 publications

Changes in Cx43 and NaV1.5 Expression Precede the Occurrence of Substantial Fibrosis in Calcineurin-Induced Murine Cardiac Hypertrophy

Changes in Cx43 and NaV1.5 Expression Precede the Occurrence of Substantial Fibrosis in Calcineurin-Induced Murine Cardiac Hypertrophy

Reduced Cx43 Expression Triggers Increased Fibrosis Due to Enhanced Fibroblast Activity

Structure and Function of Cochlear Gap Junctions and Implications for the Translation of Cochlear Gene Therapies

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