Developmental regulation of connexin 40 gene expression in mouse heart correlates with the differentiation of the conduction system
Version of Record online: 3 FEB 2005
Copyright © 1995 Wiley-Liss, Inc.
Volume 204, Issue 4, pages 358–371, December 1995
How to Cite
Delorme, B., Dahl, E., Jarry-guichard, T., Marics, I., Briand, J.-P., Willecke, K., Gros, D. and Théveniau-Ruissy, M. (1995), Developmental regulation of connexin 40 gene expression in mouse heart correlates with the differentiation of the conduction system. Dev. Dyn., 204: 358–371. doi: 10.1002/aja.1002040403
- Issue online: 3 FEB 2005
- Version of Record online: 3 FEB 2005
- Manuscript Accepted: 7 JUL 1995
- Manuscript Received: 30 MAR 1995
- Gap junctions;
- Conduction system;
In adult mouse heart, CX40 is expressed in the atria and the proximal part of the ventricular conduction system (the His bundle and the upper parts of the bundle branches). This cardiac tissue is specialized in the conduction of the electrical impulse. CX40 is the only mouse connexin known to be expressed in these parts of the adult conductive tissue and is thus considered as a marker of the conduction system. In the present report, we investigated CX40 expression and distribution during mouse heart development. We first demonstrate that CX40 mRNA is regulated throughout development, as are other heart connexin transcripts, i.e., CX37, CX43, and CX45, with a decreasing abundance as development proceeds. We also show that the CX40 transcript and protein are similarly regulated, CX40 being expressed as two different phosphorylated and un-phosphorylated forms of 41 and 40 kDa, respectively. Surprisingly, distribution studies demonstrated that CX40 is widely expressed in 11 days post-coitum (dpc) embryonic heart, where it is detected in both the atria and ventricle primordia. As development proceeds, the CX40 distribution pattern in the atria is maintained, whereas a more dynamic pattern is observed in the ventricles. From 14 dpc onwards, as the adult ventricular conduction system differentiates, CX40 decreases in the trabecular network and it is preferentially distributed in the ventricular conduction system. CX40 is thus the marker of the early differentiating conduction system. It is hypothesized that the conduction system is present in unorganized “embryonic” form at 11 dpc and trans-differentiates by 14 dpc into the adult conduction system. © 1995 wiley-Liss, Inc.