Structure, sequence and expression of the mouse Cx43 gene encoding connexin 43

Area of Science:

• Molecular Biology
• Developmental Biology
• Genetics

Background:

• Gap junctions facilitate intercellular communication via ion and small molecule diffusion.
• Connexin 43 (Cx43) is a key gap junction protein implicated in development and growth.
• Cx43 gene expression patterns are critical for understanding its developmental roles.

Purpose of the Study:

• To clone and characterize mouse Cx43 cDNAs and the Cx43 gene.
• To analyze the differential expression of Cx43 transcripts during early mouse embryogenesis.
• To investigate the transcriptional regulation and evolutionary conservation of the Cx43 gene.

Main Methods:

• Cloning and sequencing of Cx43 cDNAs from a mouse embryo cDNA library.
• RNA isolation and analysis to determine regional Cx43 transcript expression.
• Screening of a mouse genomic DNA library to isolate the Cx43 gene.
• Restriction mapping, sequencing, RNase protection, and primer extension analyses.
• Comparative sequence analysis of Cx43 across multiple species.

Main Results:

• Authentic 43-kDa Cx43 cDNAs were successfully cloned and sequenced.
• Cx43 transcripts showed differential expression in the 7.5-day mouse embryo, present in the embryo proper but absent in the extraembryonic region.
• The Cx43 gene consists of two exons separated by a 10.5-kb intron in the 5'-UTR.
• A single transcription start point (tsp) was identified for both embryonic and adult Cx43 transcripts.
• Sequence analysis revealed a conserved 3'-UTR with AUUUA motifs, suggesting potential transcript instability.

Conclusions:

• The study provides a detailed characterization of the mouse Cx43 gene structure and its early embryonic expression pattern.
• Differential Cx43 expression highlights its specific roles in embryonic development.
• Conserved regulatory elements and 3'-UTR motifs suggest important functional and evolutionary significance of Cx43.