Cardiovascular Research Advance Access [Accepted Manuscript] published online on August 4, 2008
Cardiovascular Research, doi:10.1093/cvr/cvn203
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
FATE OF Cx43 IN CARDIAC TISSUE HARBOURING A DISEASE-LINKED Cx43 MUTANT
* Departments of Anatomy and Cell Biology & Physiology and Pharmacology University of Western Ontario London, Ontario, Canada N6A-5C1
** Address Correspondence to: Dale W Laird, PhD Departments of Anatomy and Cell Biology & Physiology and Pharmacology University of Western Ontario London, Ontario, Canada N6A-5C1 Tel: 519 661-2111 x86827 Fax: 519 850-2562 Email: dale.laird{at}schulich.uwo.ca
Aim: More than 40 mutations in the GJA1 gene encoding connexin43 (Cx43) have been linked to oculodentodigital dysplasia (ODDD), a pleiotropic, autosomal dominant disorder. We hypothesized that even with a significant reduction in the levels of Cx43 in a mutant mouse model of ODDD (Gja1Jrt/+) harbouring a G60S mutation (Cx43G60S), cardiomyocyte function may only be moderately compromised given that a majority of mutant mice typically survive.
Methods: Western blotting and quantitative RT-PCR in conjunction with immunofluorescence were used to assess the expression and localization of Cx43 in hearts and cultured cardiomyocytes from wild-type and Gja1Jrt/+ mice. Dye coupling and dual whole cell patch-clamp recordings were also used to assess the gap junction channel status in cultured cardiomyocytes from wild-type and mutant mice.
Results: Cardiac tissue from adult Gja1Jrt/+ mice revealed a 60-80% reduction in Cx43 protein with a preferential loss of the highly phosphorylated forms of Cx43. Compensation via the up-regulation of Cx40 or Cx45 was not observed. Immunofluorescent analysis of cultured cardiomyocytes revealed a trafficking defect, with a decrease in Cx43 plaques and a large population of Cx43 being retained in the Golgi apparatus. However, cultured cardiomyocytes from mutant mice remained beating with an over 50% decrease in coupling conductance.
Conclusion: These results suggest that the Cx43G60S mutant impairs normal trafficking and function of co-expressed Cx43 with no dramatic effect on cardiomyocyte function, suggesting that Cx43 is biosynthesized in excess of an essential need.
KEYWORDS connexin43; gap junctions; cardiomyocytes; mutant mice
Time for primary review: 18 days
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  D. Tong, X. Lu, H.-X. Wang, I. Plante, E. Lui, D. W. Laird, D. Bai, and G. M. Kidder A Dominant Loss-of-Function GJA1 (Cx43) Mutant Impairs Parturition in the Mouse Biol Reprod, June 1, 2009; 80(6): 1099 - 1106. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Tong, D. Colley, R. Thoo, T. Y. Li, I. Plante, D. W. Laird, D. Bai, and G. M. Kidder Oogenesis defects in a mutant mouse model of oculodentodigital dysplasia Dis. Model. Mech., March 1, 2009; 2(3-4): 157 - 167. [Abstract] [Full Text] [PDF]
|
|