Gene structure and promoter analysis of the human GJB6 gene encoding connexin 30

Connexins (Cx) are the protein subunits of gap junctions, which play an important role in cell-to-cell communication. We characterized the genomic structure of the human GJB6 gene, encoding connexin 30 (C x 30), and showed that it differs from most connexin-encoding genes. GJB6 presents six different exons, some of which can be alternatively spliced. We also mapped a basal promoter sequence active in a human keratinocyte cell line which responds to the activation of the EGF receptor. One of the non-encoding exons of GJB6, which has been described in brain C x 30 cDNA, was not found in cDNA obtained from human keratinocytes, suggesting tissue-specific splicing.     

The genomic structure, chromosome location, and analysis of the human DKK1 head inducer gene as a candidate for holoprosencephaly

Holoprosencephaly (HPE) is the most common developmental defect of the brain and face in humans. Here we report the analysis of the human ortholog of dkk-1 as a candidate gene for HPE. We determined the genomic structure of the human gene DKK1 and mapped it to chromosome 10q11.2. Functional analysis of four missense mutations identified in HPE patients revealed preserved activity in head induction assays in frogs suggesting a limited role for this gene in HPE pathogenesis.